JP4811649B2 - Chemical substance measuring method in soil and chemical substance measuring apparatus in soil - Google Patents

Chemical substance measuring method in soil and chemical substance measuring apparatus in soil Download PDF

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JP4811649B2
JP4811649B2 JP2006086057A JP2006086057A JP4811649B2 JP 4811649 B2 JP4811649 B2 JP 4811649B2 JP 2006086057 A JP2006086057 A JP 2006086057A JP 2006086057 A JP2006086057 A JP 2006086057A JP 4811649 B2 JP4811649 B2 JP 4811649B2
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紀夫 中山
存 小渕
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本発明は、土壌中の間隙水中に含まれる金属イオン等の化学物質測定方法及び土壌中の化学物質測定装置に関するものである。 The present invention relates to a method for measuring chemical substances such as metal ions contained in pore water in soil and a chemical substance measuring apparatus in soil .

土壌中の金属成分の分析は各方面で検討され、以下の開発が行われてきた。
土壌中に含まれる侵入要素に、溶媒を導入させる要素、侵入液を通した状態で電圧差を測定することにより化学成分を検出するシステムが知られている（特許文献１）。
又抽出液からイオン透過膜により抽出する電気透析することも知られている（特許文献２）。
土壌中に含まれる金属イオン濃度を定量する方法として、土壌を採取した後、目的とする金属イオンを化学的に抽出しうる抽出剤を加えた水溶液中にこれを分散させ、この金属イオンを水溶液中に抽出・溶解させた後、この水溶液を湿式分析やイオンセンサー、イオンクロマトグラフ等を用いる機器分析により金属イオンの分析を行う手法が通常、広く用いられていた。かかる従来例として、水酸化バリウム水溶液を用いてカリウム、カルシウム、マグネシウム濃度を測定する手法がある（特許文献３）。
この手法はまず、分析する土壌を採取し水酸化バリウム水溶液中に分散させ、往復振とう機により振とうした後、遠心分離、濾過し、土壌中のカリウム、カルシウム、マグネシウムイオンを抽出した抽出液を作成する。さらにこの抽出液に硫酸水溶液を加え、中和すると共に水溶液中のバリウムイオンを難溶性の硫酸バリウムとして析出させ濾過し、水溶液中のバリウムを除去したカリウム、カルシウム、マグネシウムイオン水溶液とする。これをマルチイオンメータで測定し、カリウム、カルシウム、マグネシウム濃度を同時に測定するものである。
又、複数個の土壌サンプルからイオン化成分を抽出する成分を抽出して、イオン化成分を測定する自動化装置が開発されている（特許文献４、５）。 Analysis of metal components in soil has been studied in various fields, and the following developments have been made.
A system for detecting a chemical component by measuring a voltage difference in a state where an intruding element contained in soil contains a solvent and an intruding liquid is known (Patent Document 1).
It is also known to electrodialyze from an extract with an ion permeable membrane (Patent Document 2).
As a method for quantifying the concentration of metal ions contained in the soil, after the soil is collected, it is dispersed in an aqueous solution to which an extractant capable of chemically extracting the target metal ions is added, and the metal ions are dispersed in the aqueous solution. In general, a method of analyzing metal ions by wet analysis, instrument analysis using an ion sensor, an ion chromatograph or the like after the aqueous solution is extracted and dissolved therein has been widely used. As such a conventional example, there is a technique of measuring potassium, calcium, and magnesium concentrations using an aqueous barium hydroxide solution (Patent Document 3).
In this method, first, the soil to be analyzed is collected, dispersed in an aqueous barium hydroxide solution, shaken with a reciprocating shaker, then centrifuged and filtered to extract potassium, calcium, and magnesium ions in the soil. Create Further, an aqueous sulfuric acid solution is added to the extract to neutralize it, and barium ions in the aqueous solution are precipitated as sparingly soluble barium sulfate and filtered to obtain an aqueous potassium, calcium, and magnesium ion solution from which barium in the aqueous solution has been removed. This is measured with a multi-ion meter, and the concentrations of potassium, calcium and magnesium are measured simultaneously.
Moreover, the automation apparatus which extracts the component which extracts an ionization component from several soil samples, and measures an ionization component is developed (patent documents 4, 5).

上記のように土壌中の金属イオン濃度を測定する際に、サンプルを採取して水溶媒抽出してこれを測定する際に自動化を行うにしても大掛かりな装置であり、多くの工程を経て測定されるものとなっている。このようなことから土中に水を供給してセンサーを挿入しイオン濃度を検出することも知られている（特許文献６）。
これは土壌中にセンサーを挿入して測定をおこなうものの、土壌に注水するため土壌の間隙水中の化学物質濃度をそのまま定量するものではなく、また、測定対象は所謂土壌の肥沃さなどを対象とする測定対象物質に限られる。 As described above, when measuring the metal ion concentration in the soil, it is a large-scale device even if it is automated when taking a sample, extracting it with an aqueous solvent and measuring it, and measuring it through many steps It is supposed to be. For this reason, it is also known to detect the ion concentration by supplying water into the soil and inserting a sensor (Patent Document 6).
Although this is done by inserting a sensor into the soil, it does not quantitate the chemical concentration in the pore water of the soil as it is poured into the soil, and the measurement target is the so-called soil fertility. Limited to substances to be measured.

近年、土壌汚染の拡大及び深刻化に伴い、土壌の間隙水中に含まれる重金属イオン等の有害な化学物質を検出・定量し、その汚染状況を評価・監視することに対する需要が増大している。また、放射性廃棄物の地層処分技術において、地下処分場は還元性の雰囲気に管理されることが必要である（非特許文献１）。処分場が還元性環境にあることを確認する一つの方法として、この処分場内部に充填される粘土（ベントナイト）の間隙水中に含まれ、酸化状態により濃度が変化する金属イオン（鉄イオン等）の濃度を測定して評価する測定技術の開発が要求され、期待されている。
特開２−２０３２６４号公報 特開４−３４３６２号公報 特開平１１−３７９９６号公報 特開２０００−５５９０９号公報 特開２０００−５５９１０号公報 特開平１０−１４４０２号公報 “わが国における高レベル放射性廃棄物地層処分の技術的信頼性−地層処分研究開発第２次取りまとめ−総論レポート”、核燃料サイクル開発機構、IV−１９（１９９９） In recent years, with the expansion and seriousness of soil contamination, there is an increasing demand for detecting and quantifying harmful chemical substances such as heavy metal ions contained in pore water of soil, and evaluating and monitoring the contamination status. Moreover, in the geological disposal technology of radioactive waste, it is necessary to manage the underground disposal site in a reducing atmosphere (Non-patent Document 1). One method for confirming that the disposal site is in a reducing environment is a metal ion (iron ion, etc.) that is contained in the pore water of clay (bentonite) that fills the disposal site and whose concentration changes depending on the oxidation state. Development and development of a measurement technique for measuring and evaluating the concentration of water is required and expected.
Japanese Patent Laid-Open No. 2-203264 Japanese Patent Laid-Open No. 4-34362 Japanese Patent Laid-Open No. 11-37996 JP 2000-55909 A JP 2000-55910 A Japanese Patent Laid-Open No. 10-14402 "Technological reliability of geological disposal of high-level radioactive waste in Japan-Geological disposal research and development 2nd report-General report", Nuclear Fuel Cycle Development Organization, IV-19 (1999)

本発明の課題は、土壌の間隙水に含まれる金属成分の検出に関し、また、特定条件下に汚染された土壌の間隙水に含まれる金属成分の検出に関し、土壌中にセンサーを直接挿入することにより土壌の間隙水に含まれる金属成分の検出・定量する手法を提供することである。   An object of the present invention relates to detection of metal components contained in pore water of soil, and to detection of metal components contained in pore water of soil contaminated under specific conditions, by directly inserting a sensor into the soil. This is to provide a method for detecting and quantifying metal components contained in pore water of soil.

本発明者らは、土壌中で、複数の物質が存在し、特定の物質の個々の状況を分析することは困難であると予想されるにもかかわらず、土壌の間隙水に注目し、土壌の間隙水中に含まれる重金属イオン等の有害な化学物質を検出・定量する場合、及び処分場が還元性環境にあることを確認する際に、この処分場内部に充填される粘土（ベントナイト）の間隙水中に含まれ、酸化状態により濃度が変化する金属イオン（鉄イオン等）の濃度を測定する場合には、基準電極を囲んで、導電性の電極（測定用電極）及び対極が設けられている検出手段を組み立てて、測定対象の化学物質の酸化還元反応に伴う酸化還元電流を測定すると、土壌の間隙水の化学物質濃度に比例するということを新たに見出した。 In spite of the fact that there are multiple substances in the soil and it is expected that it is difficult to analyze the individual status of a particular substance, the inventors have focused on the pore water in the soil, When detecting and quantifying harmful chemical substances such as heavy metal ions contained in the pore water of the soil, and when confirming that the disposal site is in a reducing environment, the clay (bentonite) filled inside this disposal site When measuring the concentration of metal ions (iron ions, etc.) contained in the pore water and whose concentration varies depending on the oxidation state, a conductive electrode (measuring electrode) and a counter electrode are provided surrounding the reference electrode. As a result, it was newly found out that the redox current associated with the redox reaction of the chemical substance to be measured is proportional to the chemical concentration of soil pore water.

具体的には、土壌の間隙水を含む土壌中に基準電極を囲んで、導電性の電極（測定用電極）及び対極が設けられている検出手段を配置し、この電極の電位を、この土壌の間隙水中で含まれる化学物質の酸化電位より貴な電位、または還元電位より卑な電位に保ち、そのとき当該電極表面で進行する酸化または還元反応に伴い生じる酸化または還元電流を測定することにより、当該化学物質を検出し、その濃度を定量することを見出した。   Specifically, a detection means provided with a conductive electrode (measuring electrode) and a counter electrode is arranged in a soil containing pore water of the soil, and a conductive electrode (measuring electrode) and a counter electrode are provided. By measuring the oxidation or reduction current generated by the oxidation or reduction reaction proceeding on the electrode surface at that time, the potential is nobler than the oxidation potential of the chemical substance contained in It was found that the chemical substance was detected and its concentration was quantified.

また、前記の場合に測定対象とする化学物質以外にも複数の化学物質が存在する場合には、それぞれの化学物質の酸化・還元反応が異なる電位で進行することに着目し、この複数の化学物質を含む土壌中に導電性の電極を配置し、この電極の電位を自然電位より貴方向に、測定対象とする化学物質の酸化電位より貴な電位まで上昇させてこのとき当該電極表面に生じる酸化電流を測定し、この測定対象とする化学物質の酸化電位より貴な電位領域における電流より、当該酸化電位以下かつ当該酸化電位傍における酸化電流を減じ、この差に相当する電流値から当該測定対象とする化学物質を検出し濃度を定量するか、或いはこの電極の電位を自然電位より卑方向に、測定対象とする化学物質の還元電位より卑な電位まで降下させてこのとき当該電極表面に生じる還元電流を測定し、この測定対象とする化学物質の還元電位より卑な電位領域における電流から、当該還元電位以下かつ当該還元電位傍における還元電流を減じ、この差に相当する電流値から当該測定対象とする化学物質を検出し濃度を定量することができることを見出した。   In addition, when there are a plurality of chemical substances other than the chemical substance to be measured in the above case, pay attention to the fact that the oxidation / reduction reaction of each chemical substance proceeds at different potentials. A conductive electrode is placed in the soil containing the substance, and the potential of this electrode is raised in the noble direction from the natural potential to a noble potential from the oxidation potential of the chemical substance to be measured. Measure the oxidation current, subtract the oxidation current below the oxidation potential and near the oxidation potential from the current in the noble potential region than the oxidation potential of the chemical substance to be measured, and measure the current from the current value corresponding to this difference At this time, the target chemical substance is detected and the concentration is quantified, or the potential of this electrode is lowered from the natural potential to the base potential lower than the reduction potential of the chemical substance to be measured. The reduction current generated on the electrode surface is measured, and the current corresponding to this difference is obtained by subtracting the reduction current below the reduction potential and near the reduction potential from the current in the potential region lower than the reduction potential of the chemical substance to be measured. It was found that the chemical substance to be measured can be detected from the value and the concentration can be quantified.

又、土壌の間隙水中に含まれる重金属イオン等の有害な化学物質を検出・定量する場合、及び処分場が還元性環境にあることを確認する際に、この処分場内部に充填される粘土（ベントナイト）の間隙水中に含まれ、酸化状態により濃度が変化する金属イオン（鉄イオン等）の濃度を測定する場合には、測定対象の化学物質を含む土壌中に、導電性の電極を配置し、この電極の電位を、この土壌の間隙水中に含まれる当該化学物質の酸化電位より貴な電位、または還元電位より卑な電位に保ち、そのとき当該電極表面で進行する酸化または還元反応に伴い生じる酸化または還元電流を測定することにより、当該化学物質を検出し濃度を定量することができる化学物質測定装置が提供できることを見出した。   In addition, when detecting and quantifying harmful chemical substances such as heavy metal ions contained in the pore water of the soil, and when confirming that the disposal site is in a reducing environment, clay ( When measuring the concentration of metal ions (iron ions, etc.) that are contained in the pore water of bentonite and whose concentration varies depending on the oxidation state, a conductive electrode is placed in the soil containing the chemical substance to be measured. The potential of the electrode is maintained at a potential that is nobler than the oxidation potential of the chemical substance contained in the pore water of the soil or a potential that is lower than the reduction potential. It was found that a chemical substance measuring apparatus capable of detecting the chemical substance and quantifying the concentration by measuring the generated oxidation or reduction current can be provided.

又、土壌の間隙水中に含まれる重金属イオン等の有害な化学物質を検出・定量する場合、及び処分場が還元性環境にあることを確認する際に、この処分場内部に充填される粘土（ベントナイト）の間隙水中に含まれ、酸化状態により濃度が変化する金属イオン（鉄イオン等）の濃度を測定する場合に、複数の化学物質を含む土壌中に導電性の電極を配置し、この電極の電位を自然電位より貴方向に、測定対象とする化学物質の酸化電位より貴な電位まで上昇させてこのとき当該電極表面に生じる酸化電流を測定し、この測定対象とする化学物質の酸化電位より貴な電位領域における電流より、当該酸化電位以下かつ当該酸化電位傍における酸化電流を減じ、この差に相当する電流値から当該測定対象とする化学物質を検出し濃度を定量するか、或いはこの電極の電位を自然電位より卑方向に、測定対象とする化学物質の還元電位より卑な電位まで降下させてこのとき当該電極表面に生じる還元電流を測定し、この測定対象とする化学物質の還元電位より卑な電位領域における電流から、当該還元電位以下かつ当該還元電位傍における還元電流を減じ、この差に相当する電流値から当該測定対象とする化学物質を検出し濃度を定量する化学物質測定装置が提供できることを見出した。
具体的には、前記課題を達成するために本発明（請求項１に係る発明）にあっては、
土壌の間隙水中に含まれる化学物質を検出・定量する土壌中の化学物質測定方法において、
間隙水を含む測定対象としての土壌中に、導電性電極を配置し、
前記導電性電極の電位を、前記土壌の間隙水中に含まれる当該化学物質における酸化反応の平衡電位より貴な電位であって該化学物質の次に貴な化学物質の平衡電位よりも卑な電位に保ちつつ、該導電性電極の表面で進行する酸化反応に伴い生じる酸化電流を測定酸化電流として測定すると共に、
前記導電性電極の電位を、前記土壌の間隙水中に含まれる前記化学物質における酸化反応の平衡電位ないし該平衡電位近傍の電位に保ちつつ、該導電性電極の表面で進行する酸化反応に伴い生じる酸化電流を基準測定酸化電流として測定して、
前記測定酸化電流と前記基準測定酸化電流との差分を求めるか、或いは、
前記導電性電極の電位を、前記土壌の間隙水中に含まれる当該化学物質における還元反応の平衡電位より卑な電位であって該化学物質の次に卑な化学物質の平衡電位よりも貴な電位に保ちつつ、該導電性電極の表面で進行する還元反応に伴い生じる還元電流を測定還元電流として測定すると共に、
前記導電性電極の電位を、前記土壌の間隙水中に含まれる前記化学物質における還元反応の平衡電位ないしは該平衡電位近傍の電位に保ちつつ、該導電性電極の表面で進行する還元反応に伴い生じる還元電流を基準測定還元電流として測定して、
前記測定還元電流と前記基準測定還元電流との差分を求め、
その上で、前記差分に基づき、当該化学物質を検出し濃度を定量する構成としてある。
また、前記課題を達成するために本発明（請求項２に係る発明）にあっては、
土壌の間隙水中に含まれる一種類の化学物質を検出・定量する土壌中の化学物質測定方法において、
間隙水を含む測定対象としての土壌中に、導電性電極を配置し、
前記導電性電極の電位を、前記土壌の間隙水中に含まれる当該化学物質の酸化反応の平衡電位より貴な電位、または還元反応の平衡電位より卑な電位に保ちつつ、該導電性電極表面で進行する酸化反応または還元反応に伴い生じる酸化電流または還元電流を測定電流として測定し、
前記測定の結果に基づき、当該化学物質を検出し濃度を定量する構成としてある。この請求項２の好ましい態様としては、請求項５，６の記載のとおりである。
さらに、前記課題を達成するために本発明（請求項３に係る発明）にあっては、
土壌の間隙水中に含まれる複数種類の化学物質を検出・定量する土壌中の化学物質測定方法において、
間隙水を含む測定対象としての土壌中に、導電性電極を配置し、
前記導電性電極の電位を、電位の貴方向に向けて順に、前記各化学物質における酸化反応の平衡電位より貴な電位であって該化学物質の次に貴な化学物質の平衡電位よりも卑な電位に保ちつつ、該導電性電極の表面で進行する各酸化反応に伴い生じる酸化電流を前記各化学物質の測定酸化電流としてそれぞれ測定すると共に、
前記各化学物質の測定酸化電流の測定に対応させて、前記導電性電極の電位を、該各化学物質における酸化反応の平衡電位ないしは該平衡電位近傍の電位に保ちつつ、該導電性電極の表面で進行する各酸化反応に伴い生じる酸化電流を前記各化学物質の基準測定酸化電流としてそれぞれ測定するか、或いは、
前記導電性電極の電位を、電位の卑方向に向けて順に、前記各化学物質における還元反応の平衡電位より卑な電位であって該化学物質の次に卑な化学物質の平衡電位よりも貴な電位に保ちつつ、該導電性電極の表面で進行する各還元反応に伴い生じる還元電流を前記各化学物質の測定還元電流としてそれぞれ測定すると共に、
前記各化学物質の測定還元電流の測定に対応させて、前記導電性電極の電位を、該各化学物質における還元反応の平衡電位ないしは該平衡電位近傍の電位に保ちつつ、該導電性電極の表面で進行する各還元反応に伴い生じる還元電流を前記各化学物質の基準測定還元電流としてそれぞれ測定し、
その上で、前記各化学物質の測定酸化電流と該各測定電流に対応する基準測定酸化電流との差分、又は前記各化学物質の測定還元電流と該各測定還元電流に対応する基準測定還元電流との差分をそれぞれ求め、
前記各差分に基づき、前記各化学物質を検出し濃度を定量する構成としてある。
さらにまた、前記課題を達成するために本発明（請求項４に係る発明）にあっては、
土壌の間隙水中に含まれて平衡電位が異なる第１、第２の２種類の化学物質を検出・定量する土壌中の化学物質測定方法において、
間隙水を含む測定対象としての土壌中に、導電性電極を配置し、
前記第２化学物質の酸化反応の平衡電位が前記第１化学物質の酸化反応の平衡電位よりも貴であるときには、前記導電性電極の電位を、自然電位より貴な電位であって該第２化学物質の平衡電位よりも卑な電位に保ちつつ、該導電性電極の表面で進行する酸化反応に伴い生じる酸化電流を該第１化学物質の測定酸化電流として測定して、該第１化学物質の測定酸化電流により該第１化学物質を検出し濃度を定量し、
続いて、前記導電性電極の電位を、前記第２化学物質における酸化反応の平衡電位より貴な電位に保ちつつ、該導電性電極の表面で進行する酸化反応に伴い生じる酸化電流を該第２化学物質の測定酸化電流として測定すると共に、該導電性電極の電位を、該第２化学物質における酸化反応の平衡電位ないしは該平衡電位近傍の電位に保ちつつ、該導電性電極の表面で進行する酸化反応に伴い生じる酸化電流を該第２化学物質の基準測定酸化電流として測定し、その上で、該第２化学物質の測定酸化電流と該第２化学物質の基準測定酸化電流との差分に基づき、該第２化学物質を検出し濃度を定量し、
前記第２化学物質の還元反応の平衡電位が前記第１化学物質の還元反応の平衡電位よりも卑であるときには、前記導電性電極の電位を、自然電位より卑な電位であって該第２化学物質の平衡電位よりも貴な電位に保ちつつ、該導電性電極の表面で進行する還元反応に伴い生じる還元電流を該第１化学物質の測定還元電流として測定して、該第１化学物質の測定還元電流により該第１化学物質を検出し濃度を定量し、
続いて、前記導電性電極の電位を、前記第２化学物質における還元反応の平衡電位より卑な電位に保ちつつ、該導電性電極の表面で進行する還元反応に伴い生じる還元電流を該第２化学物質の測定還元電流として測定すると共に、該導電性電極の電位を、該第２化学物質における還元反応の平衡電位ないしは該平衡電位近傍の電位に保ちつつ、該導電性電極の表面で進行する還元反応に伴い生じる還元電流を該第２化学物質の基準測定還元電流として測定し、その上で、該第２化学物質の測定還元電流と該第２化学物質の基準測定還元電流との差分に基づき、該第２化学物質を検出し濃度を定量する構成としてある。
また、前記課題を達成するために本発明（請求項７に係る発明）にあっては、
土壌の間隙水中に含まれる化学物質を検出・定量する土壌中の化学物質測定装置において、
検出手段として、
間隙水を含む測定対象としての土壌中に接触される基準電極と、
前記基準電極の近傍に設けられ、間隙水を含む測定対象としての土壌中に接触される測定用電極及び対極と、が備えられ、
測定手段として、
前記基準電極を基準として前記測定用電極を目的の電位に保ち、該測定用電極の表面に生じる酸化・還元反応に伴い、該測定用電極と対極との間に流れる酸化・還元電流を測定する電源及び信号処理装置が備えられている構成とされている。この請求項７の好ましい態様としては、請求項８以下の記載のとおりである。 In addition, when detecting and quantifying harmful chemical substances such as heavy metal ions contained in the pore water of the soil, and when confirming that the disposal site is in a reducing environment, clay ( When measuring the concentration of metal ions (iron ions, etc.) that are contained in pore water of bentonite and whose concentration changes depending on the oxidation state, a conductive electrode is placed in the soil containing multiple chemical substances. Measure the oxidation current generated on the electrode surface at this time by raising the potential of the electrode in a noble direction from the natural potential to a noble potential above the oxidation potential of the chemical substance to be measured, and the oxidation potential of the chemical substance to be measured Whether the current in the more noble potential region is less than the oxidation potential and near the oxidation potential, and detects the chemical substance to be measured from the current value corresponding to this difference to quantify the concentration. Alternatively, the potential of this electrode is lowered in the base direction from the natural potential to a base potential lower than the reduction potential of the chemical substance to be measured, and at this time, the reduction current generated on the electrode surface is measured, and the chemical substance to be measured A chemical that subtracts the reduction current below the reduction potential and near the reduction potential from the current in the potential region lower than the reduction potential of the substance, detects the chemical substance to be measured from the current value corresponding to this difference, and quantifies the concentration It has been found that a substance measuring device can be provided.
Specifically, in order to achieve the above object, in the present invention (the invention according to claim 1),
In the method for measuring chemical substances in soil, which detects and quantifies chemical substances contained in the pore water of the soil,
A conductive electrode is placed in the soil as the measurement target including pore water,
The potential of the conductive electrode is higher than the equilibrium potential of the oxidation reaction in the chemical substance contained in the pore water of the soil and is lower than the equilibrium potential of the chemical substance next to the chemical substance. While measuring the oxidation current generated by the oxidation reaction proceeding on the surface of the conductive electrode as a measured oxidation current,
This occurs with the oxidation reaction proceeding on the surface of the conductive electrode while maintaining the potential of the conductive electrode at the equilibrium potential of the oxidation reaction in the chemical substance contained in the pore water of the soil or a potential in the vicinity of the equilibrium potential. Measure the oxidation current as the reference measurement oxidation current,
Obtaining a difference between the measured oxidation current and the reference measured oxidation current, or
The potential of the conductive electrode is lower than the equilibrium potential of the reduction reaction in the chemical substance contained in the pore water of the soil, and is higher than the equilibrium potential of the next lower chemical substance after the chemical substance. While measuring the reduction current caused by the reduction reaction proceeding on the surface of the conductive electrode as a measurement reduction current,
This occurs with the reduction reaction proceeding on the surface of the conductive electrode while maintaining the potential of the conductive electrode at the equilibrium potential of the reduction reaction in the chemical substance contained in the pore water of the soil or a potential in the vicinity of the equilibrium potential. Measure the reduction current as the reference measurement reduction current,
Find the difference between the measured reduction current and the reference measurement reduction current,
Based on the difference, the chemical substance is detected and the concentration is quantified.
In order to achieve the above object, the present invention (the invention according to claim 2)
In chemical measuring how in soil for detecting and quantifying an kinds of chemical substances contained in the pore water of the soil,
A conductive electrode is placed in the soil as the measurement target including pore water,
While maintaining the potential of the conductive electrode at a potential higher than the equilibrium potential of the oxidation reaction of the chemical substance contained in the pore water of the soil or a potential lower than the equilibrium potential of the reduction reaction, Measure the oxidation current or reduction current that accompanies the ongoing oxidation or reduction reaction as the measurement current,
Based on the result of the measurement, the chemical substance is detected and the concentration is quantified. Preferred embodiments of claim 2 are as described in claims 5 and 6.
Further, in order to achieve the above object, in the present invention (the invention according to claim 3),
In the method for measuring chemical substances in soil, which detects and quantifies multiple types of chemical substances contained in the pore water of the soil,
A conductive electrode is placed in the soil as the measurement target including pore water,
The potential of the conductive electrode is set in order toward the noble direction of the potential in order, and is lower than the equilibrium potential of the chemical substance next to the chemical substance, which is nobler than the equilibrium potential of the oxidation reaction in each chemical substance. While measuring the oxidation current generated by each oxidation reaction proceeding on the surface of the conductive electrode as a measured oxidation current of each chemical substance, while maintaining a low potential,
Corresponding to the measurement of the measured oxidation current of each chemical substance, the surface of the conductive electrode is maintained while maintaining the potential of the conductive electrode at the equilibrium potential of the oxidation reaction in each chemical substance or a potential in the vicinity of the equilibrium potential. Or measuring the oxidation current generated with each oxidation reaction proceeding as a reference measurement oxidation current for each chemical substance, or
The potential of the conductive electrode is set in order toward the base of the potential in order, and the potential is lower than the equilibrium potential of the reduction reaction in each chemical substance and is higher than the equilibrium potential of the next base chemical substance. While measuring a reduction current generated by each reduction reaction proceeding on the surface of the conductive electrode as a measured reduction current of each chemical substance while maintaining a low potential,
Corresponding to the measurement of the reduction current of each chemical substance, the surface of the conductive electrode is maintained while maintaining the potential of the conductive electrode at or near the equilibrium potential of the reduction reaction in the chemical substance. Measure the reduction current that occurs with each reduction reaction proceeding in step 1 as the standard measurement reduction current for each chemical substance,
Then, the difference between the measured oxidation current of each chemical substance and the reference measured oxidation current corresponding to each measured current, or the measured measurement current of each chemical substance and the reference measured reduction current corresponding to each measured reduction current Each difference with
Based on the differences, the chemical substances are detected and the concentrations are quantified.
Furthermore, in order to achieve the above object, in the present invention (the invention according to claim 4),
In the method for measuring chemical substances in soil, which detects and quantifies the first and second kinds of chemical substances contained in the pore water of the soil and having different equilibrium potentials,
A conductive electrode is placed in the soil as the measurement target including pore water,
When the equilibrium potential of the oxidation reaction of the second chemical substance is nobler than the equilibrium potential of the oxidation reaction of the first chemical substance, the potential of the conductive electrode is set to a potential nobler than the natural potential and the second potential. While maintaining a potential lower than the equilibrium potential of the chemical substance, an oxidation current generated by an oxidation reaction that proceeds on the surface of the conductive electrode is measured as a measured oxidation current of the first chemical substance, and the first chemical substance is measured. The first chemical substance is detected and quantified by the measured oxidation current of
Subsequently, while maintaining the potential of the conductive electrode at a potential higher than the equilibrium potential of the oxidation reaction in the second chemical substance, an oxidation current generated by the oxidation reaction that proceeds on the surface of the conductive electrode is generated. Measured as an oxidation current of the chemical substance and proceeds on the surface of the conductive electrode while maintaining the potential of the conductive electrode at the equilibrium potential of the oxidation reaction in the second chemical substance or a potential near the equilibrium potential The oxidation current generated by the oxidation reaction is measured as the reference measurement oxidation current of the second chemical substance, and then the difference between the measurement oxidation current of the second chemical substance and the reference measurement oxidation current of the second chemical substance is calculated. Based on this, the second chemical substance is detected and the concentration is quantified,
When the equilibrium potential of the reduction reaction of the second chemical substance is lower than the equilibrium potential of the reduction reaction of the first chemical substance, the potential of the conductive electrode is lower than the natural potential and the second potential is lower. The reduction current generated by the reduction reaction that proceeds on the surface of the conductive electrode is measured as a measurement reduction current of the first chemical substance while maintaining a potential nobler than the equilibrium potential of the chemical substance, and the first chemical substance is measured. The first chemical substance is detected by the reduction current measured to determine the concentration,
Subsequently, while maintaining the potential of the conductive electrode at a base potential lower than the equilibrium potential of the reduction reaction in the second chemical substance, the reduction current generated by the reduction reaction proceeding on the surface of the conductive electrode is changed to the second current. Measured as a reduction current of a chemical substance and proceeds on the surface of the conductive electrode while maintaining the potential of the conductive electrode at or near the equilibrium potential of the reduction reaction in the second chemical substance The reduction current generated by the reduction reaction is measured as the reference measurement reduction current of the second chemical substance, and then the difference between the measurement reduction current of the second chemical substance and the reference measurement reduction current of the second chemical substance is calculated. Based on this, the second chemical substance is detected and the concentration is quantified.
Further, in order to achieve the above object, in the present invention (the invention according to claim 7),
In the soil chemical substance measuring device that detects and quantifies chemical substances contained in the pore water of the soil,
As a detection means,
A reference electrode in contact with the soil as a measurement object including pore water;
A measuring electrode and a counter electrode, which are provided in the vicinity of the reference electrode and are brought into contact with soil as a measuring object including pore water;
As a measuring means,
The measurement electrode is maintained at a target potential with respect to the reference electrode, and an oxidation / reduction current flowing between the measurement electrode and the counter electrode is measured in accordance with an oxidation / reduction reaction occurring on the surface of the measurement electrode. A power supply and a signal processing device are provided. The preferred embodiment of claim 7 is as described in claim 8 and the following.

本発明の方法及び装置によれば、土壌中の間隙水中に含まれる金属イオン等の化学物質を、電極反応を利用して土壌中の測定しようとする原位置に電極を固定し、連続的に検出・定量することができる。具体的には、土壌中の測定しようとする原位置に電極を固定し測定し、連続的に検出・定量することができる。測定装置として電極を固定したことにより一定の条件下に土壌中の状態として均一な測定をおこなうことができる。土壌の間隙水中に含まれる重金属イオン等の有害な化学物質を検出・定量し、その汚染状況を評価・監視するために使用できる。また、放射性廃棄物の地層処分技術において、この処分場内部に充填される粘土（ベントナイト）の間隙水中に含まれ、酸化状態により濃度が変化する金属イオン（鉄イオン等）の濃度を測定することにより処分場が還元性環境にあることを確認することに適用できる。
また、土壌（砂、粘土等も含む）のほか、水溶液を含む汚泥、粉体試料等の内部に検出器本体を埋設して使用することができる。 According to the method and apparatus of the present invention, the chemical substance such as metal ions contained in the pore water in the soil is fixed to the original position to be measured in the soil using the electrode reaction, and continuously. Can be detected and quantified. Specifically, the electrode can be fixed at the original position to be measured in the soil, measured, and continuously detected and quantified. By fixing the electrode as a measuring device, it is possible to perform uniform measurement as a state in the soil under certain conditions. It can be used to detect and quantify harmful chemical substances such as heavy metal ions contained in soil pore water, and to evaluate and monitor the contamination status. Also, in the geological disposal technology for radioactive waste, measure the concentration of metal ions (iron ions, etc.) that are contained in the pore water of clay (bentonite) filled in the disposal site and whose concentration varies depending on the oxidation state. This can be applied to confirm that the disposal site is in a reducing environment.
In addition to soil (including sand, clay, etc.), the detector main body can be embedded in sludge containing an aqueous solution, powder sample, and the like.

以下、本発明について詳細に説明する。
図１は、一成分の化学物質の測定装置を説明する図を示す。
本発明の測定装置は、検出手段と測定手段とを有している。検出手段としては、検出器本体６の内部を貫通して設けられる基準電極５と、その検出器本体６の一方の端部に基準電極５を囲むようにして設けられる導電性の電極（測定用電極８及び対極７）と、が備えられている。測定手段としては、基準電極５を基準として測定電極８を目的の電位に保ち、測定電極８表面に流れる酸化・還元電流を測定する電源及び信号処理装置２が備えられている。これらは、図１に示すように、導線１を用いて結線することにより構成されている。
同図では検出器本体６は円筒状になっており、内部の空洞に基準電極５が配置されているが、基準電極５は検出器本体６外部の測定用電極８近傍に配置されてもよい。
この構成とは逆に測定用電極８及び対極７、或いはそのいずれか一方のみが検出器本体６の円筒内面に配置されてもよい。この際、基準電極５は円筒型検出器の内部、外部のいずれにおかれてもよい。
測定電極（導電性電極）８表面に流れる酸化・還元電流を測定する電源及び信号処理装置２は、さらに、記録手段によって測定結果を記録することができる。
検出器本体６は電気絶縁性の材料で構成される。
測定に際しては、この基準電極５の先端、及び測定用電極８、対極７は同図に示すように、土壌９中に挿入される。同図では検出器本体６は円筒状になっており、内部の空洞に基準電極５が配置されているが、基準電極５は検出器本体６外部の測定用電極８近傍に配置されてもよい。 Hereinafter, the present invention will be described in detail.
FIG. 1 is a diagram illustrating an apparatus for measuring a one-component chemical substance.
The measuring device of the present invention has a detecting means and a measuring means. The detecting means, the detector body and the reference electrode 5 provided through the interior of 6, the detector one end of the conductive provided so as to surround the reference electrode 5 to the unit electrode of the main body 6 (measurement electrode 8 And a counter electrode 7). As a measuring means, a power source and a signal processing device 2 for measuring the oxidation / reduction current flowing on the surface of the measurement electrode 8 while keeping the measurement electrode 8 at a target potential with reference to the reference electrode 5 are provided. As shown in FIG. 1, these are configured by connecting using a conducting wire 1.
In the figure, the detector body 6 has a cylindrical shape, and the reference electrode 5 is disposed in the internal cavity. However, the reference electrode 5 may be disposed in the vicinity of the measurement electrode 8 outside the detector body 6. .
Contrary to this configuration, only the measurement electrode 8 and the counter electrode 7 , or only one of them may be arranged on the inner surface of the cylinder of the detector body 6 . At this time, the reference electrode 5 may be placed either inside or outside the cylindrical detector.
The power supply and signal processing device 2 for measuring the oxidation / reduction current flowing on the surface of the measurement electrode (conductive electrode) 8 can further record the measurement result by the recording means.
The detector body 6 is made of an electrically insulating material.
At the time of measurement, the tip of the reference electrode 5 , the measurement electrode 8 , and the counter electrode 7 are inserted into the soil 9 as shown in FIG. In the figure, the detector body 6 has a cylindrical shape, and the reference electrode 5 is disposed in the internal cavity. However, the reference electrode 5 may be disposed in the vicinity of the measurement electrode 8 outside the detector body 6. .

図４は、二成分の化学物質を測定する測定装置を説明する図を示す。
本発明の測定装置も、検出手段と測定手段とを有している。検出手段としては、検出器本体６の内部を貫通して設けられる第１、第２基準電極としての基準電極５、１４と、その検出器本体６の一方の端部に基準電極５、１４を囲むようにして設けられる第１、第２の導電性電極（第１測定用電極としての測定用電極８及び第１対極としての対極７、第２測定用電極としての測定用電極１５及び第２対極としての対極１３）と、が備えられている。測定手段としては、基準電極５を基準として測定電極８を目的の電位に保ち、測定電極８表面に流れる酸化・還元電流を測定する電源及び信号処理装置２と、基準電極１４を基準として測定電極１５を目的の電位に保ち、測定電極１５表面に流れる酸化・還元電流を測定する電源及び信号処理装置１０と、が備えられている。これらは、図４に示すように、導線１を用いて結線することにより構成されている。
この構成とは逆に測定用電極８（１５）及び対極７（１３）、或いはそのいずれか一方のみが検出器本体６の円筒内面に配置されてもよい。この際、基準電極５（１４）は円筒型検出器の内部、外部のいずれにおかれてもよい。
測定電極８（１５）表面に流れる酸化・還元電流を測定する電源及び信号処理装置２（１０）は、さらに、記録手段によって測定結果を記録することができる。
検出器本体６は電気絶縁性の材料で構成される。
測定に際しては、この基準電極５、１４の先端、及び測定用電極８，１５、対極７，１３は同図に示すように、土壌９中に挿入される。同図では検出器本体６は円筒状になっており、内部の空洞に基準電極５、１４が配置されているが、基準電極５、１４は検出器外部の測定用電極近傍に配置されてもよい。 FIG. 4 is a diagram illustrating a measuring apparatus that measures a two-component chemical substance.
The measurement apparatus of the present invention also has a detection means and a measurement means. The detection means, first provided through the inside of the detector body 6, a reference electrode 5, 14 as a second reference electrode, the reference electrode 5, 14 at one end of the detector body 6 First and second conductive electrodes ( a measurement electrode 8 as a first measurement electrode and a counter electrode 7 as a first counter electrode, a measurement electrode 15 as a second measurement electrode, and a second counter electrode) Counter electrode 13). As a measuring means , the measuring electrode 8 is kept at a target potential with the reference electrode 5 as a reference, the power supply and signal processing device 2 for measuring the oxidation / reduction current flowing on the surface of the measuring electrode 8 , and the measuring electrode with the reference electrode 14 as a reference. 15 is provided with a power source and a signal processing device 10 for measuring the oxidation / reduction current flowing on the surface of the measurement electrode 15 while maintaining 15 at a target potential . As shown in FIG. 4, these are configured by connecting using a conducting wire 1.
Contrary to this configuration, the measurement electrode 8 (15) and the counter electrode 7 (13) or only one of them may be disposed on the inner surface of the cylinder of the detector body 6 . At this time, the reference electrode 5 (14) may be placed either inside or outside the cylindrical detector.
The power supply and signal processing device 2 (10) for measuring the oxidation / reduction current flowing on the surface of the measurement electrode 8 (15) can further record the measurement result by the recording means.
The detector body 6 is made of an electrically insulating material.
In the measurement, the tips of the reference electrodes 5 and 14 , the measurement electrodes 8 and 15 , and the counter electrodes 7 and 13 are inserted into the soil 9 as shown in FIG. In the figure, the detector body 6 is cylindrical and the reference electrodes 5 and 14 are disposed in the internal cavity. However, the reference electrodes 5 and 14 may be disposed in the vicinity of the measurement electrodes outside the detector. Good.

ここで言う間隙水とは土壌中に存在する吸着水及び自由水を示している。吸着水は土壌溶液とも呼ばれ、土壌を構成する粒子間に毛管力、吸着力（土壌粒子−水分子間の分子間力や土壌粒子の荷電と双極子としての水の間に働く静電気力等に起因する）によりゆるく結合し保有される水である。自由水は土壌粒子とは結合・吸着していない水で、土壌構造内にできた割れ目など比較的大きな隙間に存在する水である。土壌粒子の結晶構造中に含まれる結晶水、沸石水等は含まない。本発明はこの吸着水・自由水中に溶解する化学物質を測定の対象とするものである。金属イオン等の可溶な化学物質はこの中に溶解しており、また、土壌粒子に固体として含まれる化学物質も平衡濃度としてこの中に溶出すると思われるので、上記間隙水中の化学物質濃度を測定することによりこの土壌の汚染状況を把握することができると考えられる。   The pore water mentioned here indicates adsorbed water and free water present in the soil. Adsorbed water is also called soil solution. Capillary force and adsorption force between particles constituting soil (molecular force between soil particle and water molecule, electrostatic force acting between soil particle charge and water as dipole, etc. Water that is more loosely bound and retained. Free water is water that is not bound or adsorbed to soil particles and is present in relatively large gaps such as cracks formed in the soil structure. Crystal water, zeolite water, etc. contained in the crystal structure of soil particles are not included. In the present invention, a chemical substance dissolved in the adsorbed water / free water is to be measured. Soluble chemical substances such as metal ions are dissolved in this, and chemical substances contained in soil particles as solids are also expected to elute into this as an equilibrium concentration. It is considered that the soil contamination can be grasped by measuring.

土壌の間隙水に含まれ得る土壌中の成分としては、以下の成分が測定対象となる。
R（酸化を受ける化学物質の意味である）としては、金属及び、その金属化合物イオンとして、Co2+、Ag+、Mn2+、Tl+、Hg2 2+、Sn2+、Cu+、Tl+、Cr2+、U3+、等が、金属化合物以外のイオンとしてCl-、ClO3 -、Br-、CNS-、I-、SO3 2-、CN-、等がある。
また、電荷を持たない溶存分子としてI2、H2O2、H2、等がある。
O（還元を受ける化学物質の意味である）としては、金属及び、その金属化合物イオンとして、Mn3+、MnO4 -、Au3+、Cl2、Cr2O7 -、PdCl6 2-、AuCl4 -、Pd2+、Hg2+、Ag+、PtCl4 2-、PtCl6 2-、PdCl4 2-、UO2 +、BrO3 -、Cu+、Cu2+、Sn4+、Co(NH3)6 3+、UO2 2+、Sn2+、Pb2+、Ni2+、V3+、Co2+、Tl+、In3+、Cd2+、Cr3+、Fe2+、Ga3+、U4+、Zn2+、Cd(CN)4 2-、Mn2+、Zr4+、Ti2+、Al3+、等がある。金属化合物以外のイオンとしてClO3 -、ClO3 -、ClO4 -、IO3 -、ClO2 -、I3 -、ClO4 -、NO3 -、SO3 2-、SO4 2-、AsO2 -、等がある。また、電荷を持たない溶存分子としてCl2、Br2、O2、H2O2、I2、CO2、等がある。 As components in the soil that can be contained in the pore water of the soil, the following components are to be measured.
As R (which means a chemical substance that undergoes oxidation), as a metal and its metal compound ions, Co 2+ , Ag + , Mn 2+ , Tl + , Hg 2 2+ , Sn 2+ , Cu + , Tl + , Cr 2+ , U 3+ , etc. include Cl − , ClO 3 − , Br − , CNS − , I − , SO 3 2− , CN − , etc. as ions other than metal compounds.
Examples of dissolved molecules having no charge include I 2 , H 2 O 2 , H 2 , and the like.
As O (which means a chemical substance that undergoes reduction), as a metal and its metal compound ion, Mn 3+ , MnO 4 − , Au 3+ , Cl 2 , Cr 2 O 7 − , PdCl 6 2− , AuCl 4 − , Pd 2+ , Hg 2+ , Ag + , PtCl 4 2− , PtCl 6 2− , PdCl 4 2− , UO 2 + , BrO 3 − , Cu + , Cu 2+ , Sn 4+ , Co (NH 3 ) 6 3+ , UO 2 2+ , Sn 2+ , Pb 2+ , Ni 2+ , V 3+ , Co 2+ , Tl + , In 3+ , Cd 2+ , Cr 3+ , Fe 2 + , Ga 3+ , U 4+ , Zn 2+ , Cd (CN) 4 2− , Mn 2+ , Zr 4+ , Ti 2+ , Al 3+ , and the like. As ions other than metal compounds, ClO 3 − , ClO 3 − , ClO 4 − , IO 3 − , ClO 2 − , I 3 − , ClO 4 − , NO 3 − , SO 3 2− , SO 4 2− , AsO 2 -, and the like. In addition, dissolved molecules having no charge include Cl 2 , Br 2 , O 2 , H 2 O 2 , I 2 , CO 2 , and the like.

測定に当たっては、この測定用電極８（１５）が基準電極５（１４）に対し、電源及び信号処理手段２（１０）により、測定対象とする化学物質の酸化電位より貴な電位または還元電位より卑な電位に保たれる。
この時の電位は電圧計４で測定され、監視される。この際、電極表面には式（１）のような酸化反応、及び式（２）のような還元反応が進行し、それぞれ式（３）、及び式（４）に示すような、電極表面の化学物質濃度に比例した電流が生じ、対極との間に電流が流れる。
R → R+ ＋ e- （１）
O ＋ e- → O- （２）
I1＝AC1・exp{B(E-E1)/KT} （３）
I2＝DC2・exp{-G(E-E2)/KT} （４）
ここに、Rは前記酸化を受ける化学物質、R＋は前記その酸化により生成した化学物質、Oは還元を受ける化学物質、O-はその還元により生成した化学物質である。上記の化学物質には、各種イオンのほか、水中に溶解しているH2O2、O2、H2等の本来電荷を持たない化学種も含まれる。
また、I1は上記式（１）の酸化反応により電極表面に発生する電流、A、Bは定数、C1は電極表面におけるRの濃度、Eは電極電位、E1は式（１）の反応に対する平衡電位（酸化電位）、Kは気体定数、Tは温度である。また、I2は上記式（２）の還元反応により電極表面に発生する電流、D、Gは定数、C2は電極表面におけるOの濃度、Eは電極電位、E2は式（２）の反応に対する平衡電位（還元電位）である。 In measurement, the measurement electrode 8 (15) is compared to the reference electrode 5 (14) by a power source and a signal processing means 2 (10) from a potential more precious than the oxidation potential of the chemical substance to be measured or a reduction potential. It is kept at a low potential.
The potential at this time is measured and monitored by the voltmeter 4. At this time, an oxidation reaction such as formula (1) and a reduction reaction such as formula (2) proceed on the electrode surface, and the electrode surface as shown in formula (3) and formula (4) respectively. A current proportional to the chemical concentration is generated, and a current flows between the counter electrode.
R → R + + e - ( 1)
O + e - → O - ( 2)
I 1 = AC 1 · exp {B (EE 1 ) / KT} (3)
I 2 = DC 2 · exp {-G (EE 2 ) / KT} (4)
Here, R is a chemical substance that undergoes the oxidation, R + is a chemical substance that is produced by the oxidation, O is a chemical substance that undergoes reduction, and O − is a chemical substance that is produced by the reduction. In addition to various ions, the above-mentioned chemical substances include chemical species having no inherent charge such as H 2 O 2 , O 2 , and H 2 dissolved in water.
I 1 is the current generated on the electrode surface by the oxidation reaction of the above formula (1), A and B are constants, C 1 is the concentration of R on the electrode surface, E is the electrode potential, and E 1 is the formula (1) The equilibrium potential (oxidation potential) for the reaction, K is the gas constant, and T is the temperature. I 2 is the current generated on the electrode surface by the reduction reaction of the above formula (2), D and G are constants, C 2 is the concentration of O on the electrode surface, E is the electrode potential, E 2 is the formula (2) It is the equilibrium potential (reduction potential) for the reaction.

従って、式（１）の酸化反応においてはその平衡電位においては電流が生じず、またこの平衡電位では式（１）の逆反応も進行しているが、電極電位をこれより十分貴にすると、式（１）の酸化反応のみが支配的となり、式（２）に示す電極表面の化学物質濃度に比例した電流が流れるようになる。この電流を電流計３で測定することにより土壌の間隙水中の化学物質濃度を検出・定量することが可能になる。また、電極電位を貴にするほど電流は大きくなって高感度で測定をすることが可能になる。この模様を模式的に図２に示した。同図において、平衡電位をV1で示してある。なお、電極電位が平衡電位より極めて高い（貴な）場合、電流は式（２）に示す電極反応ではなく、間隙水内部から電極表面に化学物質が拡散する速度によって支配されるようになるため、電流は電極電位に依存せず一定になる場合があるが、この拡散速度は間隙水中の化学物質濃度に比例するため、この場合もこの電位領域の電流から、化学物質濃度を測定することができる。   Therefore, in the oxidation reaction of the formula (1), no current is generated at the equilibrium potential, and the reverse reaction of the formula (1) also proceeds at the equilibrium potential. Only the oxidation reaction of Formula (1) becomes dominant, and a current proportional to the chemical substance concentration on the electrode surface shown in Formula (2) flows. By measuring this current with the ammeter 3, it becomes possible to detect and quantify the chemical substance concentration in the pore water of the soil. In addition, as the electrode potential is made noble, the current increases and measurement can be performed with high sensitivity. This pattern is schematically shown in FIG. In the figure, the equilibrium potential is indicated by V1. When the electrode potential is extremely higher (noble) than the equilibrium potential, the current is not controlled by the electrode reaction shown in Equation (2), but is governed by the rate at which chemical substances diffuse from the pore water to the electrode surface. The current may be constant without depending on the electrode potential, but since this diffusion rate is proportional to the chemical concentration in the pore water, the chemical concentration can also be measured from the current in this potential region. it can.

同様に、式（２）の還元反応においては、電極電位を式（２）の反応の平衡電位より卑にすると、電極表面の化学物質濃度に比例した電流が流れるようになり、この電流を測定することにより土壌の間隙水中の化学物質濃度が検出・定量される。また、電極電位を卑にするほど電流は大きくなって高感度で測定をすることが可能になる。   Similarly, in the reduction reaction of formula (2), when the electrode potential is made lower than the equilibrium potential of the reaction of formula (2), a current proportional to the chemical concentration on the electrode surface flows, and this current is measured. By doing so, the chemical substance concentration in the pore water of the soil is detected and quantified. Further, the current becomes larger as the electrode potential is made lower, and measurement can be performed with high sensitivity.

式（１）の酸化反応では、例えば式（５）、式（６）の反応により、間隙水中のI-イオンやSn2+イオンが検出・定量できる。
2I- → I2 ＋ 2e- （５）
Sn2+ → Sn4+ + 2e- （６）
また、式（２）の還元反応では、例えば式（７）、式（８）の反応により、間隙水中のFe2+イオンやO2が検出・定量できる。
Fe2+ + 2e- → Fe （７）
O2 + 2H2O + 4e- → 4OH- （８） In the oxidation reaction of formula (1), for example, I − ions and Sn 2+ ions in pore water can be detected and quantified by the reactions of formulas (5) and (6).
2I - → I 2 + 2e - (5)
Sn 2+ → Sn 4+ + 2e - (6)
Further, in the reduction reaction of the formula (2), Fe 2+ ions and O 2 in the pore water can be detected and quantified by the reactions of the formulas (7) and (8), for example.
Fe 2+ + 2e - → Fe ( 7)
O 2 + 2H 2 O + 4e - → 4OH - (8)

土壌の間隙水中に、測定対象の化学物質以外に複数の化学物質が含まれる場合、それぞれの化学物質に対し、その酸化反応の平衡電位が卑である順に式（１）に相当する酸化反応が進行し、式（３）に相当する酸化電流が流れる。
この模様を模式的に図３に示す。同図は最も卑な平衡電位を持つ化学物質1（平衡電位：V1）、次に卑な平衡電位を持つ化学物質２（平衡電位：V2）、最も貴な平衡電位を持つ化学物質3（平衡電位：V3）が間隙水中に存在する例を示すものである。
この場合、電極電位がV1においては電流が流れない（複数の化学物質が存在する場合、この電流が流れない電位V1は自然電位と呼ばれる）が、これより貴な電位とすると同図に示す如く酸化電流が流れるようになる。この電流は式（３）に従い増大し、電極電位がV2に達すると化学物質２による酸化反応も進行して同図の様にこの反応による電流も加わり、測定電流は増大する。
同様に電位がV3に達するとこの最も貴な平衡電位を持つ化学物質3の酸化反応による電流も加わり、測定電流は増大する。測定対象物質が化学物質２の場合には電流を測定しながら電位をV1より上昇させ、電位がV2に達したときの電流I2を測定する。さらに電位を上昇させ、このときの測定電流IをIとすると、V2とV3の間の電位領域においてはIとI2との差I-I2が式（３）に従うので、この値を求めることにより、間隙水中の測定対象化学物質濃度を検出・定量することができる。上記は酸化反応に基づき説明したが、これは還元反応においても同様に適用できる。 When a plurality of chemical substances are contained in the pore water of the soil in addition to the chemical substance to be measured, the oxidation reaction corresponding to the formula (1) is performed for each chemical substance in the order of the equilibrium potential of the oxidation reaction. The oxidation current corresponding to the equation (3) flows.
This pattern is schematically shown in FIG. The figure shows chemical substance 1 with the lowest equilibrium potential (equilibrium potential: V1), then chemical substance 2 with the lowest equilibrium potential (equilibrium potential: V2), and chemical substance 3 with the most noble equilibrium potential (equilibrium) This shows an example in which electric potential: V3) is present in pore water.
In this case, current does not flow when the electrode potential is V1 (when there are multiple chemical substances, the potential V1 at which this current does not flow is called a natural potential). Oxidation current flows. This current increases according to the equation (3). When the electrode potential reaches V2, the oxidation reaction by the chemical substance 2 proceeds, and the current due to this reaction is also added as shown in FIG.
Similarly, when the potential reaches V3, a current due to the oxidation reaction of the chemical substance 3 having the most noble equilibrium potential is also added, and the measured current increases. When the substance to be measured is chemical substance 2, the potential is increased from V1 while measuring the current, and the current I2 when the potential reaches V2 is measured. If the potential is further increased and the measured current I at this time is I, the difference I-I2 between I and I2 follows the formula (3) in the potential region between V2 and V3. It is possible to detect and quantify the concentration of the chemical substance to be measured in the pore water. Although the above has been described based on an oxidation reaction, this can also be applied to a reduction reaction.

図１の検出器本体６は、好適にはシリカ、アルミナ、ジルコニア、チッ化珪素等のセラミック或いはポリエチレン樹脂、フッ素樹脂、塩化ビニール樹脂、アクリル樹脂等の樹脂で製作されるが、これはガラス、岩石など、他の絶縁性に優れた材料を使用して製作することも可能である。導線１には金属、導電性樹脂、炭素材料等、好適には銅、金、銀、白金、カーボンファイバー等が用いられるが、これは導電性に優れたこれ以外の材料で製作することも可能である。導線の表面は絶縁のため、絶縁性材料で被覆される。好適にはガラス、或いはフッ素樹脂等の樹脂が用いられるが、これは絶縁性に優れた他の材料でも良い。測定用電極８（１５）、対極７（１３）には、好適には、金、白金、銀等の貴金属が用いられるが、これは銅、鉄、ニッケル、アルミニウム、亜鉛、鉛、チタン等の他の導電性金属、ステンレス鋼等の鉄鋼、真ちゅうなど導電性の合金で製作しても良い。またこの他、グラファイト等の炭素材料や、導電性高分子を用いることも可能である。基準電極には好適には硫酸銅電極（Cu/CuSO4）、甘こう電極、塩化銀電極（Ag/AgCl）、臭化銀電極（Ag/AgBr）、ヨウ化銀電極（Ag/Ag）、或いはアルミニウム、亜鉛やその合金の粉末等が用いられるが、これは安定した電位を示す他の電極でも良い。 The detector body 6 of FIG. 1 is preferably made of ceramic such as silica, alumina, zirconia, silicon nitride, or a resin such as polyethylene resin, fluororesin, vinyl chloride resin, acrylic resin, which is made of glass, It is also possible to manufacture using other materials having excellent insulating properties such as rocks. The conductor 1 is made of metal, conductive resin, carbon material, etc., preferably copper, gold, silver, platinum, carbon fiber, etc., but it can also be made of other materials with excellent conductivity. It is. The surface of the conductive wire is covered with an insulating material for insulation. Preferably, glass or a resin such as a fluororesin is used, but this may be another material excellent in insulation. The measurement electrode 8 (15) and the counter electrode 7 (13) are preferably made of a noble metal such as gold, platinum, silver, etc., which may be copper, iron, nickel, aluminum, zinc, lead, titanium, etc. Other conductive metals, steels such as stainless steel, and conductive alloys such as brass may be used. In addition, it is also possible to use a carbon material such as graphite or a conductive polymer. The reference electrode is preferably a copper sulfate electrode (Cu / CuSO 4 ), a gypsum electrode, a silver chloride electrode (Ag / AgCl), a silver bromide electrode (Ag / AgBr), a silver iodide electrode (Ag / Ag), Alternatively, powder of aluminum, zinc, or an alloy thereof is used, but this may be another electrode exhibiting a stable potential.

図１では円筒形の検出器本体６に測定用電極８、対極７が装置されているが、これは矩形、楕円形その他の他の形状の断面を持つ、棒の外表面または管の外表面、内表面に配置されても良く、また、単に土壌９中に測定用電極８、対極７、基準電極５をそれぞれ別個に差し込んだものでも良い。また、基準電極５が対極７を兼ねることも可能である。また、検出器本体６と基準電極５を一体の構造としても良い。 In FIG. 1, a measuring electrode 8 and a counter electrode 7 are mounted on a cylindrical detector body 6 , which has an outer surface of a rod or a tube having a rectangular, oval or other cross section. The electrode 8 for measurement, the counter electrode 7 , and the reference electrode 5 may be separately inserted into the soil 9 . In addition, the reference electrode 5 can also serve as the counter electrode 7 . The detector body 6 and the reference electrode 5 may be integrated.

図４に本発明の別の実施形態を示す。この例は、土壌中に測定対象とする化学物質が2種類存在する場合に使用するものである。
この例では、図１と同様に、検出器に、第１の化学物質を測定するための電源及び信号処理装置２、基準電極５、対極７等が装置されている他、もう一組、第２の化学物質を測定するための電源及び信号処理装置１０、電流計１１、電圧計１２、対極１３、基準電極１４、測定用電極１５が装置されている。測定に際してはこのそれぞれの測定用電極８（１５）を、それぞれの基準電極５（１４）に対し別個に、各化学物質の酸化反応の平衡電位より貴または還元反応の平衡電位より卑な電位に保ち、各々独立に測定された電流から、それぞれの化学物質を検出・定量する。図４の例では電源及び信号処理装置及び電極系が２組装置されているが、測定対象とする化学物質の種類が更に多い場合は、その化学物質の数に応じて電源及び信号処理装置、電極系の数を増やせば良い。 FIG. 4 shows another embodiment of the present invention. This example is used when two types of chemical substances to be measured exist in the soil.
In this example, as in FIG. 1, the detector is provided with a power source and signal processing device 2 for measuring the first chemical substance, a reference electrode 5 , a counter electrode 7, etc. A power source and signal processing device 10 for measuring two chemical substances, an ammeter 11 , a voltmeter 12 , a counter electrode 13 , a reference electrode 14 , and a measuring electrode 15 are provided. In the measurement, each of the measurement electrodes 8 (15) is separately set with respect to the reference electrode 5 (14) to a potential lower than the equilibrium potential of the oxidation reaction of each chemical substance or lower than the equilibrium potential of the reduction reaction. Each chemical substance is detected and quantified from the current measured independently. In the example of FIG. 4, two sets of the power supply and signal processing device and the electrode system are provided. However, when there are more types of chemical substances to be measured, the power supply and signal processing device, depending on the number of chemical substances, The number of electrode systems may be increased.

以下に実施例により更に詳細に発明の内容を説明する。本発明はこれにより限定を受けるものではない。   The contents of the invention will be described in more detail with reference to the following examples. The present invention is not limited thereby.

粘土（ベントナイト）の間隙水中に含まれるFe2+の測定
図１の装置を用いて粘土（ベントナイト）の間隙水中に含まれるFe2+イオン濃度の測定を行った。
Fe2+イオンを間隙水中に含むベントナイト（間隙水中のFe2+イオン濃度：1.8x10-3mol/kg；重量含水率：98%）中に、図１の検出器を挿入し、電位を平衡電位から卑方向に掃引する際にして流れる電流を測定した。
測定用電極及び対極として白金板、基準電極として塩化銀電極（Ag/AgCl）を使用した。
粘土（ベントナイト）の間隙水中に含まれるFe2+イオン還元に伴う電流−電位曲線の実際の測定結果を図５に示した。-600mVより卑な電位、好適には-700mV以下に測定用電極を保ち、その時流れる電流を測定したものであり、平衡電位（約-600mV）より卑な電位領域で前記式（７）の還元反応による還元電流が観測された結果を示すものである。
以上の結果から、ベントナイトの間隙水中に溶解しているFe2+イオンを検出・定量分析することができることがわかった。 Measurement of Fe 2+ contained in pore water of clay (bentonite) Using the apparatus of FIG. 1, the concentration of Fe 2+ ions contained in the pore water of clay (bentonite) was measured.
1 is inserted into bentonite containing Fe 2+ ions in pore water (Fe 2+ ion concentration in pore water: 1.8x10 -3 mol / kg; moisture content: 98%), and the potential is balanced. The current flowing when sweeping from the potential in the base direction was measured.
A platinum plate was used as a measurement electrode and a counter electrode, and a silver chloride electrode (Ag / AgCl) was used as a reference electrode.
FIG. 5 shows the actual measurement results of the current-potential curve associated with the reduction of Fe 2+ ions contained in the pore water of clay (bentonite). The measurement electrode is kept at a potential lower than -600 mV, preferably less than -700 mV, and the current flowing at that time is measured. The reduction of the formula (7) in the potential range lower than the equilibrium potential (about -600 mV) The reduction current due to the reaction is observed.
From the above results, it was found that Fe 2+ ions dissolved in the pore water of bentonite can be detected and quantitatively analyzed.

図６は、図５の測定に用いたものと同じ検出器を用いて、測定用電極電位を基準電極に対し-950mVに保ち、ベントナイト（重量含水率98%）の間隙水中のFe2+イオン濃度を変化させて、Fe2+イオン濃度とその濃度において実測された電流（Fe2+イオンの還元電流）との関係を示したものである。同図に示されるようにFe2+イオン濃度と電流密度との間に直線関係が見られ、測定される電流値から、間隙水内部のFe2+イオン濃度を定量することが可能である。 FIG. 6 shows the same detector as that used in the measurement of FIG. 5, with the measurement electrode potential kept at −950 mV with respect to the reference electrode, and Fe 2+ ions in the pore water of bentonite (weight moisture content 98%). This shows the relationship between the Fe 2+ ion concentration and the current actually measured at that concentration (reduction current of Fe 2+ ions) by changing the concentration. As shown in the figure, there is a linear relationship between the Fe 2+ ion concentration and the current density, and the Fe 2+ ion concentration inside the pore water can be quantified from the measured current value.

本発明における好適な測定装置の実施形態を説明する図である。It is a figure explaining embodiment of the suitable measuring apparatus in this invention. 本発明の測定原理を説明する、土壌の間隙水中に単一の化学物質を含む場合の電流−電位曲線である。It is an electric current-potential curve in case a single chemical substance is contained in the pore water of soil explaining the measurement principle of the present invention. 本発明の測定原理を説明する、土壌の間隙水中に複数の化学物質を含む場合の電流−電位曲線である。It is an electric current-potential curve in case a some chemical substance is contained in the pore water of a soil explaining the measurement principle of this invention. 複数の成分を測定するための、複数の電極系及び電源・信号処理装置を設けた本発明の他の実施形態を示す説明図である。It is explanatory drawing which shows other embodiment of this invention provided with the several electrode system and power supply and signal processing apparatus for measuring a several component. 粘土（ベントナイト）の間隙水中に含まれるFe2+イオン還元に伴う電流−電位曲線の実際の測定結果を示す図である。It is a figure which shows the actual measurement result of the electric current-potential curve accompanying the Fe2 + ion reduction contained in the pore water of clay (bentonite). 本発明の実施例による粘土（ベントナイト）の間隙水中に含まれるFe2+イオン濃度測定結果を示す図である。It is a figure which shows the Fe2 + ion concentration measurement result contained in the pore water of the clay (bentonite) by the Example of this invention.

１ 導線
２ 電源及び信号処理装置
３ 電流計
４ 電圧計
５ 基準電極（第１基準電極）
６ 検出器本体
７ 対極（第１対極）
８ 測定用電極（第１測定用電極）
９ 土壌
10 電源及び信号処理装置
11 電流計
12 電圧計
13 対極（第２対極）
14 基準電極（第２基準電極）
15 測定用電極（第２測定用電極） 1 Conductor 2 Power Supply and Signal Processing Device 3 Ammeter 4 Voltmeter 5 Reference Electrode (First Reference Electrode)
6 Detector body 7 Counter electrode (first counter electrode)
8 Measurement electrode (first measurement electrode)
9 Soil
10 Power supply and signal processing device
11 Ammeter
12 Voltmeter
13 counter electrode (second counter electrode)
14 reference electrode (second reference electrode)
15 Measurement electrode (second measurement electrode)

Claims (11)

土壌の間隙水中に含まれる化学物質を検出・定量する土壌中の化学物質測定方法において、In the method for measuring chemical substances in soil, which detects and quantifies chemical substances contained in the pore water of the soil,
間隙水を含む測定対象としての土壌中に、導電性電極を配置し、A conductive electrode is placed in the soil as the measurement target including pore water,
前記導電性電極の電位を、前記土壌の間隙水中に含まれる当該化学物質における酸化反応の平衡電位より貴な電位であって該化学物質の次に貴な化学物質の平衡電位よりも卑な電位に保ちつつ、該導電性電極の表面で進行する酸化反応に伴い生じる酸化電流を測定酸化電流として測定すると共に、The potential of the conductive electrode is higher than the equilibrium potential of the oxidation reaction in the chemical substance contained in the pore water of the soil and is lower than the equilibrium potential of the chemical substance next to the chemical substance. While measuring the oxidation current generated by the oxidation reaction proceeding on the surface of the conductive electrode as a measured oxidation current,
前記導電性電極の電位を、前記土壌の間隙水中に含まれる前記化学物質における酸化反応の平衡電位ないし該平衡電位近傍の電位に保ちつつ、該導電性電極の表面で進行する酸化反応に伴い生じる酸化電流を基準測定酸化電流として測定して、This occurs with the oxidation reaction proceeding on the surface of the conductive electrode while maintaining the potential of the conductive electrode at the equilibrium potential of the oxidation reaction in the chemical substance contained in the pore water of the soil or a potential in the vicinity of the equilibrium potential. Measure the oxidation current as the reference measurement oxidation current,
前記測定酸化電流と前記基準測定酸化電流との差分を求めるか、或いは、Obtaining a difference between the measured oxidation current and the reference measured oxidation current, or
前記導電性電極の電位を、前記土壌の間隙水中に含まれる当該化学物質における還元反応の平衡電位より卑な電位であって該化学物質の次に卑な化学物質の平衡電位よりも貴な電位に保ちつつ、該導電性電極の表面で進行する還元反応に伴い生じる還元電流を測定還元電流として測定すると共に、The potential of the conductive electrode is lower than the equilibrium potential of the reduction reaction in the chemical substance contained in the pore water of the soil, and is higher than the equilibrium potential of the next lower chemical substance after the chemical substance. While measuring the reduction current caused by the reduction reaction proceeding on the surface of the conductive electrode as a measurement reduction current,
前記導電性電極の電位を、前記土壌の間隙水中に含まれる前記化学物質における還元反応の平衡電位ないしは該平衡電位近傍の電位に保ちつつ、該導電性電極の表面で進行する還元反応に伴い生じる還元電流を基準測定還元電流として測定して、This occurs with the reduction reaction proceeding on the surface of the conductive electrode while maintaining the potential of the conductive electrode at the equilibrium potential of the reduction reaction in the chemical substance contained in the pore water of the soil or a potential in the vicinity of the equilibrium potential. Measure the reduction current as the reference measurement reduction current,
前記測定還元電流と前記基準測定還元電流との差分を求め、Find the difference between the measured reduction current and the reference measurement reduction current,
その上で、前記差分に基づき、当該化学物質を検出し濃度を定量する、Then, based on the difference, the chemical substance is detected and the concentration is quantified.
ことを特徴とする土壌中の化学物質測定方法。A method for measuring chemical substances in soil. 土壌の間隙水中に含まれる一種類の化学物質を検出・定量する土壌中の化学物質測定方法において、
間隙水を含む測定対象としての土壌中に、導電性電極を配置し、
前記導電性電極の電位を、前記土壌の間隙水中に含まれる当該化学物質の酸化反応の平衡電位より貴な電位、または還元反応の平衡電位より卑な電位に保ちつつ、該導電性電極表面で進行する酸化反応または還元反応に伴い生じる酸化電流または還元電流を測定電流として測定し、
前記測定の結果に基づき、当該化学物質を検出し濃度を定量する、
ことを特徴とする土壌中の化学物質測定方法。 In the method for measuring chemical substances in soil, which detects and quantifies one kind of chemical substance contained in the pore water of the soil ,
A conductive electrode is placed in the soil as the measurement target including pore water ,
The potential of the conductive electrode, noble potential than the equilibrium potential of the oxidation reaction of the chemicals in the pore water of the soil or while keeping the lower potential than the equilibrium potential of the reduction reaction, in the conductive electrode surface, the oxidation current or the reduction current caused with the progress oxidation reaction or reduction reaction was measured as the measured current,
Based on the result of the measurement, the chemical substance is detected and the concentration is quantified.
A method for measuring chemical substances in soil . 土壌の間隙水中に含まれる複数種類の化学物質を検出・定量する土壌中の化学物質測定方法において、
間隙水を含む測定対象としての土壌中に、導電性電極を配置し、
前記導電性電極の電位を、電位の貴方向に向けて順に、前記各化学物質における酸化反応の平衡電位より貴な電位であって該化学物質の次に貴な化学物質の平衡電位よりも卑な電位に保ちつつ、該導電性電極の表面で進行する各酸化反応に伴い生じる酸化電流を前記各化学物質の測定酸化電流としてそれぞれ測定すると共に、
前記各化学物質の測定酸化電流の測定に対応させて、前記導電性電極の電位を、該各化学物質における酸化反応の平衡電位ないしは該平衡電位近傍の電位に保ちつつ、該導電性電極の表面で進行する各酸化反応に伴い生じる酸化電流を前記各化学物質の基準測定酸化電流としてそれぞれ測定するか、或いは、
前記導電性電極の電位を、電位の卑方向に向けて順に、前記各化学物質における還元反応の平衡電位より卑な電位であって該化学物質の次に卑な化学物質の平衡電位よりも貴な電位に保ちつつ、該導電性電極の表面で進行する各還元反応に伴い生じる還元電流を前記各化学物質の測定還元電流としてそれぞれ測定すると共に、
前記各化学物質の測定還元電流の測定に対応させて、前記導電性電極の電位を、該各化学物質における還元反応の平衡電位ないしは該平衡電位近傍の電位に保ちつつ、該導電性電極の表面で進行する各還元反応に伴い生じる還元電流を前記各化学物質の基準測定還元電流としてそれぞれ測定し、
その上で、前記各化学物質の測定酸化電流と該各測定電流に対応する基準測定酸化電流との差分、又は前記各化学物質の測定還元電流と該各測定還元電流に対応する基準測定還元電流との差分をそれぞれ求め、
前記各差分に基づき、前記各化学物質を検出し濃度を定量する、
ことを特徴とする土壌中の化学物質測定方法。 In the method for measuring chemical substances in soil, which detects and quantifies multiple types of chemical substances contained in the pore water of the soil,
A conductive electrode is placed in the soil as the measurement target including pore water,
The potential of the conductive electrode is set in order toward the noble direction of the potential in order, and is lower than the equilibrium potential of the chemical substance next to the chemical substance, which is nobler than the equilibrium potential of the oxidation reaction in each chemical substance. While measuring the oxidation current generated by each oxidation reaction proceeding on the surface of the conductive electrode as a measured oxidation current of each chemical substance, while maintaining a low potential,
Corresponding to the measurement of the measured oxidation current of each chemical substance, the surface of the conductive electrode is maintained while maintaining the potential of the conductive electrode at the equilibrium potential of the oxidation reaction in each chemical substance or a potential in the vicinity of the equilibrium potential. Or measuring the oxidation current generated with each oxidation reaction proceeding as a reference measurement oxidation current for each chemical substance, or
The potential of the conductive electrode is set in order toward the base of the potential in order, and the potential is lower than the equilibrium potential of the reduction reaction in each chemical substance and is higher than the equilibrium potential of the next base chemical substance. While measuring a reduction current generated by each reduction reaction proceeding on the surface of the conductive electrode as a measured reduction current of each chemical substance while maintaining a low potential,
Corresponding to the measurement of the reduction current of each chemical substance, the surface of the conductive electrode is maintained while maintaining the potential of the conductive electrode at or near the equilibrium potential of the reduction reaction in the chemical substance. Measure the reduction current that occurs with each reduction reaction proceeding in step 1 as the standard measurement reduction current for each chemical substance,
Then, the difference between the measured oxidation current of each chemical substance and the reference measured oxidation current corresponding to each measured current, or the measured measurement current of each chemical substance and the reference measured reduction current corresponding to each measured reduction current Each difference with
Based on each difference, the chemical substance is detected and the concentration is quantified.
A method for measuring chemical substances in soil . 土壌の間隙水中に含まれて平衡電位が異なる第１、第２の２種類の化学物質を検出・定量する土壌中の化学物質測定方法において、
間隙水を含む測定対象としての土壌中に、導電性電極を配置し、
前記第２化学物質の酸化反応の平衡電位が前記第１化学物質の酸化反応の平衡電位よりも貴であるときには、前記導電性電極の電位を、自然電位より貴な電位であって該第２化学物質の平衡電位よりも卑な電位に保ちつつ、該導電性電極の表面で進行する酸化反応に伴い生じる酸化電流を該第１化学物質の測定酸化電流として測定して、該第１化学物質の測定酸化電流により該第１化学物質を検出し濃度を定量し、
続いて、前記導電性電極の電位を、前記第２化学物質における酸化反応の平衡電位より貴な電位に保ちつつ、該導電性電極の表面で進行する酸化反応に伴い生じる酸化電流を該第２化学物質の測定酸化電流として測定すると共に、該導電性電極の電位を、該第２化学物質における酸化反応の平衡電位ないしは該平衡電位近傍の電位に保ちつつ、該導電性電極の表面で進行する酸化反応に伴い生じる酸化電流を該第２化学物質の基準測定酸化電流として測定し、その上で、該第２化学物質の測定酸化電流と該第２化学物質の基準測定酸化電流との差分に基づき、該第２化学物質を検出し濃度を定量し、
前記第２化学物質の還元反応の平衡電位が前記第１化学物質の還元反応の平衡電位よりも卑であるときには、前記導電性電極の電位を、自然電位より卑な電位であって該第２化学物質の平衡電位よりも貴な電位に保ちつつ、該導電性電極の表面で進行する還元反応に伴い生じる還元電流を該第１化学物質の測定還元電流として測定して、該第１化学物質の測定還元電流により該第１化学物質を検出し濃度を定量し、
続いて、前記導電性電極の電位を、前記第２化学物質における還元反応の平衡電位より卑な電位に保ちつつ、該導電性電極の表面で進行する還元反応に伴い生じる還元電流を該第２化学物質の測定還元電流として測定すると共に、該導電性電極の電位を、該第２化学物質における還元反応の平衡電位ないしは該平衡電位近傍の電位に保ちつつ、該導電性電極の表面で進行する還元反応に伴い生じる還元電流を該第２化学物質の基準測定還元電流として測定し、その上で、該第２化学物質の測定還元電流と該第２化学物質の基準測定還元電流との差分に基づき、該第２化学物質を検出し濃度を定量する、
ことを特徴とする土壌中の化学物質測定方法。 In the method for measuring chemical substances in soil, which detects and quantifies the first and second kinds of chemical substances contained in the pore water of the soil and having different equilibrium potentials ,
A conductive electrode is placed in the soil as the measurement target including pore water ,
When the equilibrium potential of the oxidation reaction of the second chemical substance is nobler than the equilibrium potential of the oxidation reaction of the first chemical substance, the potential of the conductive electrode is set to a potential nobler than the natural potential and the second potential. While maintaining a potential lower than the equilibrium potential of the chemical substance, an oxidation current generated by an oxidation reaction that proceeds on the surface of the conductive electrode is measured as a measured oxidation current of the first chemical substance, and the first chemical substance is measured. The first chemical substance is detected and quantified by the measured oxidation current of
Subsequently, while maintaining the potential of the conductive electrode at a potential higher than the equilibrium potential of the oxidation reaction in the second chemical substance, an oxidation current generated by the oxidation reaction that proceeds on the surface of the conductive electrode is generated. Measured as an oxidation current of the chemical substance and proceeds on the surface of the conductive electrode while maintaining the potential of the conductive electrode at the equilibrium potential of the oxidation reaction in the second chemical substance or a potential near the equilibrium potential The oxidation current generated by the oxidation reaction is measured as the reference measurement oxidation current of the second chemical substance, and then the difference between the measurement oxidation current of the second chemical substance and the reference measurement oxidation current of the second chemical substance is calculated. Based on this, the second chemical substance is detected and the concentration is quantified,
When the equilibrium potential of the reduction reaction of the second chemical substance is lower than the equilibrium potential of the reduction reaction of the first chemical substance, the potential of the conductive electrode is lower than the natural potential and the second potential is lower. The reduction current generated by the reduction reaction that proceeds on the surface of the conductive electrode is measured as a measurement reduction current of the first chemical substance while maintaining a potential nobler than the equilibrium potential of the chemical substance, and the first chemical substance is measured. The first chemical substance is detected by the reduction current measured to determine the concentration,
Subsequently, while maintaining the potential of the conductive electrode at a base potential lower than the equilibrium potential of the reduction reaction in the second chemical substance, the reduction current generated by the reduction reaction proceeding on the surface of the conductive electrode is changed to the second current. Measured as a reduction current of a chemical substance and proceeds on the surface of the conductive electrode while maintaining the potential of the conductive electrode at or near the equilibrium potential of the reduction reaction in the second chemical substance The reduction current generated by the reduction reaction is measured as the reference measurement reduction current of the second chemical substance, and then the difference between the measurement reduction current of the second chemical substance and the reference measurement reduction current of the second chemical substance is calculated. Based on this, the second chemical substance is detected and the concentration is quantified .
A method for measuring chemical substances in soil. 測定対象とする化学物質が土壌中のFe2+イオンであり、
前記導電性電極の電位を塩化銀電極（Ag/AgCl）電位に対し-600mVより卑とした電位領域に設定し、
このとき生じる還元電流からFe2+イオンを検出・定量することを特徴とする請求項２記載の土壌中の化学物質測定方法。 The chemical substance to be measured is Fe 2+ ions in the soil,
The potential of the conductive electrode to the silver electrode (Ag / AgCl) voltage chloride was set to a potential region and negative than -600 mV,
3. The method for measuring chemical substances in soil according to claim 2 , wherein Fe 2+ ions are detected and quantified from the reduction current generated at this time. 測定対象とする土壌が放射性廃棄物の地層処分技術において地下処分場に充填されるベントナイトであり、
かつ測定対象とする化学物質が当該ベントナイト中のFe2+イオンであり、
前記導電性電極の電位を塩化銀電極（Ag/AgCl）電位に対し-600mVより卑とした電位領域に設定し、このとき生じる還元電流からFe2+イオンを検出・定量することを特徴とする請求項２記載の土壌中の化学物質測定方法。 The bentonite that the soil to be measured is filled in the underground disposal site in the geological disposal technology of radioactive waste,
And the chemical substance to be measured is Fe 2+ ions in the bentonite,
The electric potential of the conductive electrode is set to a potential region lower than -600 mV with respect to the silver chloride electrode (Ag / AgCl) potential, and Fe 2+ ions are detected and quantified from the reduction current generated at this time. The method for measuring a chemical substance in soil according to claim 2 . 土壌の間隙水中に含まれる化学物質を検出・定量する土壌中の化学物質測定装置において、
検出手段として、
間隙水を含む測定対象としての土壌中に接触される基準電極と、
前記基準電極の近傍に設けられ、間隙水を含む測定対象としての土壌中に接触される測定用電極及び対極と、が備えられ、
測定手段として、
前記基準電極を基準として前記測定用電極を目的の電位に保ち、該測定用電極の表面に生じる酸化・還元反応に伴い、該測定用電極と対極との間に流れる酸化・還元電流を測定する電源及び信号処理装置が備えられている、
ことを特徴とする土壌中の化学物質測定装置。 In the soil chemical substance measuring device that detects and quantifies chemical substances contained in the pore water of the soil,
As a detection means,
A reference electrode in contact with the soil as a measurement object including pore water;
A measuring electrode and a counter electrode, which are provided in the vicinity of the reference electrode and are brought into contact with soil as a measuring object including pore water;
As a measuring means,
The measurement electrode is maintained at a target potential with respect to the reference electrode, and an oxidation / reduction current flowing between the measurement electrode and the counter electrode is measured in accordance with an oxidation / reduction reaction occurring on the surface of the measurement electrode. Power supply and signal processing device are provided,
An apparatus for measuring chemical substances in soil . 前記基準電極が筒状の検出器本体内に貫通した状態で配置され、
前記測定用電極及び前記対極が前記検出器本体に取り付けられている、
ことを特徴とする請求項７記載の土壌中の化学物質測定装置。 The reference electrode is disposed in a state of penetrating the cylindrical detector body,
The measurement electrode and the counter electrode are attached to the detector body,
The soil chemical substance measuring device according to claim 7 . 前記基準電極として、第１、第２基準電極が備えられ、
前記測定用電極として、第１、第２測定用電極が備えられ、
前記対極として、第１、第２対極が備えられ、
前記電源及び信号処理装置が、前記第１基準電極を基準として前記第１測定用電極を目的の電位に保つと共に、前記第２基準電極を基準として前記第２測定用電極を目的の電位に保つように設定されている、
ことを特徴とする請求項８記載の土壌中の化学物質測定装置。 First and second reference electrodes are provided as the reference electrodes,
As the measurement electrodes, first and second measurement electrodes are provided,
As the counter electrode, first and second counter electrodes are provided,
The power supply and the signal processing device maintain the first measurement electrode at a target potential with respect to the first reference electrode, and maintain the second measurement electrode at a target potential with reference to the second reference electrode. Is set to
The soil chemical substance measuring device according to claim 8 . 測定対象とする化学物質が土壌中のFe2+イオンであり、
前記測定用電極の電位を塩化銀電極（Ag/AgCl）電位に対し-600mVより卑とした電位領域に設定し、
このとき生じる還元電流からFe2+イオンを検出・定量することを特徴とする請求項７又は８記載の土壌中の化学物質測定装置。 The chemical substance to be measured is Fe 2+ ions in the soil,
The potential of the measurement electrode is set to a potential region that is lower than -600 mV with respect to the silver chloride electrode (Ag / AgCl) potential,
The apparatus for measuring a chemical substance in soil according to claim 7 or 8, wherein Fe 2+ ions are detected and quantified from a reduction current generated at this time. 測定対象とする土壌が放射性廃棄物の地層処分技術において地下処分場に充填されるベントナイトであり、
かつ測定対象とする化学物質が当該ベントナイト中のFe2+イオンであり、
前記測定用電極の電位を塩化銀電極（Ag/AgCl）電位に対し-600mVより卑とした電位領域に設定し、
このとき生じる還元電流からFe2+イオンを検出・定量することを特徴とする請求項７又は８記載の土壌中の化学物質測定装置。 The bentonite that the soil to be measured is filled in the underground disposal site in the geological disposal technology of radioactive waste,
And the chemical substance to be measured is Fe 2+ ions in the bentonite,
The potential of the measurement electrode is set to a potential region that is lower than -600 mV with respect to the silver chloride electrode (Ag / AgCl) potential,
The apparatus for measuring a chemical substance in soil according to claim 7 or 8, wherein Fe 2+ ions are detected and quantified from a reduction current generated at this time.
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