CN105067539A - Method for detecting mixing uniformity of soil heavy metal pollution samples - Google Patents

Abstract

The invention provides a method for detecting mixing uniformity of soil heavy metal pollution samples. The method comprises steps as follows: (1), methyl violet powder is mixed with a plurality of to-be-detected soil heavy metal pollution samples; (2), the mixed powder at different sites is selected and sampled at random; (3), the mixed powder at different sites is dissolved with ethyl alcohol respectively and prepared to form solutions; (4), light absorption values of the solutions at the level of 579 nm are measured respectively; (5), CV (coefficients of variation) of distribution of methyl violet in the mixed powder at different sites are calculated. According to the detection method, the mixing uniformity of the soil heavy metal pollution samples is reflected by comparing differences of distribution of methyl violet in the mixed powder samples at different sites, mixing uniformity of heavy metal ions in soil is accurately detected, the detection accuracy of the content of heavy metals in soil is improved later, and further treatment of pollution of heavy metals in soil is facilitated.

Description

A kind of detection method of heavy metal pollution of soil sample mixture homogeneity

Technical field

The present invention relates to heavy metal pollution of soil to detect and integrated control research field, particularly relate to a kind of detection method of heavy metal pollution of soil sample mixture homogeneity.

Background technology

Heavy metal from agricultural chemicals, waste water, mud and atmospheric sedimentation etc. mainly comprises the significant elements of bio-toxicity such as mercury (Hg), cadmium (Cd), plumbous (Pb), chromium (Cr) and metalloid arsenic (As), and have the element such as zinc (Zn), copper (Cu), nickel (Ni) of certain toxicity, pollute the closely bound up soil of living with us just step by step, excessive heavy metal can cause physiological function of plants disorder, trophic disturbance, affects the growth of plant roots and leaf; Heavy metal contaminants movability in soil is very little, not easily with water leaching, is not microbial degradation, after entering human body by food chain, destroy nerve system of human body, immune system, skeletal system etc., and its potential hazard is very big, should be specifically noted that and prevents heavy metal to soil pollution.Study to the detection of heavy metal in soil kind, quantity to soil safety, and even vegeto-animal life security has important Protection significance.Traditional both at home and abroad soil pollution status analysis after detecting and usually adopting on-site sampling by experiment room chemical reagent and instrument carry out the method analyzed, analyze the result detected and positive directive function played to aspects such as Land_use change, project feasibility studies, Environmental capacity, environmental warning.

Due to the inhomogeneity of soil, the each soil of same survey region is caused to have otherness, in same soil, difference also has difference, therefore when practical operation, research range is divided into several sampling units, at each sampling unit, gather the soil sample of multiple sampling point, mix equally, form one " mixing sample " and measure, its measured value is equivalent to the mean value that each sampling point measures respectively, possesses representativeness.Such operation is larger than the reliability analyzing single sampling point, will greatly reduce than the workload analyzing multiple sampling point respectively.The research of current heavy metal content detection in soil, detection under sample many employings stirrer or mixer in time processing directly carry out various means, condition after stirring, process is simple, precision is not high, uniformity coefficient does not often reach requirement of experiment, for subsequent experimental brings either large or small error, be therefore difficult to meet the sample needs that nowadays new and high technology means detect.

Methyl violet pigment tracer technique is used for feed mixing field, domestic also rarely have methyl violet pigment tracer technique is applied in the detection method of heavy metal pollution of soil sample standard deviation evenness.What existing methyl violet tracer adopted is methyl violet powder, and in order to enable the tracer of small amount be evenly distributed in feed, then the particle diameter of methyl violet powder needed 200 mesh sieves.The preparation method of existing methyl violet tracer is simple, directly methyl violet is pulverized, and crosses 200 mesh sieves, obtains methyl violet tracer.Authorization Notice No. be CN102928368B patent document discloses a kind of method measuring feed uniformity coefficient, comprise the following steps: be that more than 95% ethanol dissolves methyl violet by concentration expressed in percentage by volume, obtained methyl violet solution; Described obtained methyl violet solution is mixed with tracer carrier, stirs, dry, obtain methyl violet tracer; Then methyl violet tracer is added in feed and prepare feed sample; Cloud test is carried out to feed sample.

Summary of the invention

The invention provides a kind of detection method of heavy metal pollution of soil sample mixture homogeneity, react the mixture homogeneity situation of heavy metal pollution of soil sample by the difference of methyl violet distribution in the biased sample that compares different loci.Realize the accurate detection of heavy metal ion mixture homogeneity in soil, improve the accuracy of follow-up heavy metal in soil content detection, be convenient to the further improvement that heavy metal in soil pollutes.

A detection method for heavy metal pollution of soil sample mixture homogeneity, comprises the following steps:

(1) by methyl violet powder and the heavy metal pollution of soil sample mixing to be measured of some parts, mixed-powder is obtained;

(2) in mixed-powder, random selecting different loci samples;

(3) mixed-powder of different loci dissolves with ethanol respectively, is configured to solution;

(4) light absorption value of described solution at 579nm place is measured respectively;

(5) by the coefficient of variation CV of methyl violet distribution in following formulae discovery different loci mixed-powder;

$CV=S/\stackrel{\‾}{x}\×100\%$

S gets by whole site the standard deviation of light absorption value corresponding to mixed-powder, get by whole site the average of light absorption value corresponding to mixed-powder.As CV < 10%, think that heavy metal pollution of soil sample to be measured mixes.

Described some parts heavy metal pollution of soil to be measured sample is the natural soil sample selecting different loci to gather in the sampling unit of a certain heavy metal pollution.

Methyl violet is as tracer, and the methyl violet content in the light absorption value reaction institute test sample basis at 579nm place, reacts the uniformity coefficient situation of sample mixing by the methyl violet content compared in different loci mixed-powder.

The granularity of described methyl violet powder and heavy metal pollution of soil sample to be measured is not more than 150 μm.The Task-size Controlling of methyl violet powder and heavy metal pollution of soil sample to be measured is below 150 μm, on the one hand the heavy metal in the soil sample to be measured of some parts is fully mixed, on the other hand the methyl violet powder of small amount is evenly distributed in mixed-powder.

Before mixing, described methyl violet powder and heavy metal pollution of soil sample to be measured are by 100 mesh sieves.The sample granularity obtained through 100 mesh sieve process is at about 150 μm.

In step (1), the weight ratio of described methyl violet powder and heavy metal pollution of soil sample total to be measured is 0.025 ~ 0.050:1000.

In step (1), the time of described mixing is 10 ~ 22min.

In step (3), dissolution mechanism is ultrasonic dissolution.Ultrasound wave can accelerate methyl violet and be dissolved in ethanol.The centrifugal supernatant obtained is methyl violet ethanolic solution.

Described ultrasonic dissolution condition is: the sound intensity of ultrasonic dissolution is 100W, and frequency is 20kHz, and the time is 30min.

The beneficial effect that the present invention possesses is:

(1) methyl violet pigment raw material enriches, is easy to get, and detects simple to operate, is convenient to carrying out smoothly of subsequent experimental;

(2) detection method of the present invention is on detecting the subsequent experimental testing process that soil sample is pollution-free, do not affect heavy metal ion in it.

Accompanying drawing explanation

Fig. 1 is heavy metal-polluted soil mixed-powder mixture homogeneity detection method schematic flow sheet in embodiment 1.

Fig. 2 is a kind of heavy metal pollution of soil sample of the present invention mixture homogeneity detection method operational flowchart.

Embodiment

Below in conjunction with specific embodiments and the drawings, the present invention is further explained.

Embodiment 1

1, using methyl violet pigment as tracer test himself stability and and sample component between interference

(1) full wavelength scanner of methyl violet pigment

Get methyl violet solid 0.1g (being accurate to 0.001g) to be dissolved in 1L absolute ethyl alcohol, be mixed with the solution of 100mg/L; Draw this solution 200 μ L, carry out 400-700nm full wavelength scanner respectively by microplate reader.The best extinction wavelength determining methyl violet is 579nm.

(2) full wavelength scanner of sample component

Be total amount by soil and heavy metal ion raw material with 10g, be heavy metal ion in formulation weight ratio: soil=1:1000 takes respectively (being accurate to 0.001g respectively), 100mL is settled to anhydrous alcohol solution, the centrifugal 5min of 9000r/min, after supernatant liquid filtering, draw sample solution 200 μ L, carry out 400-700nm full wavelength scanner by microplate reader.

(3) sample component is for the interfering detection of methyl violet pigment light absorption value

First, the methyl violet solution of preparation in aspiration step (1), measures its light absorption value 1 time respectively with spectrophotometer, repeats above step 1 time at interval of 30min, repeat 20 times, detects pigment self stability; The calculating coefficient of variation is: 0.42%, shows that the methyl violet solution of preparation in step (1) possesses stability.

Then the solution that a step (1) and step (2) configure respectively is got, sonic oscillation 30min after stirring, and be settled to the centrifugal 5min of 9000r/min after 100mL with absolute ethyl alcohol, finally by after supernatant liquid filtering, filtrate containing methyl violet is measured light absorption value with spectrophotometer in 579nm place, if 20 groups of repetitions, result shows: the light absorption value of mixed solution is approximate the same with the light absorption value of simple methyl violet pigment.Illustrate that methyl violet is very little by the impact of sample component.

2, the uniformity coefficient of heavy metal in soil ion distribution is detected

The soil sample of the heavy metal pollution under laboratory condition Imitating natural conditions, to be mixed with certain content experiment soil and heavy metal powder successively all cross 60 orders, 80 orders, 100 object multi-gradient sieves, according to formula mixing, add porphyrize by the dosage of 1Kg raw material interpolation 0.025g (being accurate to 0.001g) methyl violet and also cross the methyl violet pigment powder of 100 mesh sieves, the mixing of three-dimensional rotation planetary-type mixer is put into and timing together with raw material, 10, 14, 18, sample respectively during 22min, each time point sampler samples in random selecting 4 sites of mixer sample slot.

Accurately take the sample that 10g (being accurate to 0.001g) mixes, contain in 50mL beaker, with anhydrous alcohol solution, be settled to 100mL to after sample ultrasonic dissolution process 30min, with the light absorption value under spectrophotometer measurement 579nm, calculate the coefficient of variation CV in sample slot.

If the light absorption value in each site is x in sample slot ₁, x ₂, x ₃, x ₄, then the mean value of these group data

$\stackrel{\&OverBar;}{x}=\frac{(x_1+x_2+x_3+x_4)}{4}$

The standard deviation S of these group data:

$S=\sqrt{\frac{{(x_1-\stackrel{\&OverBar;}{x})}^2+{(x_2-\stackrel{\&OverBar;}{x})}^2+{(x_3-\stackrel{\&OverBar;}{x})}^2+{(x_4-\stackrel{\&OverBar;}{x})}^2}{4-1}}$

The coefficient of variation CV of these group data:

$CV/\%=\frac{S}{\stackrel{\&OverBar;}{x}}\&times;100$

Heavy metal pollution of soil sample mixture homogeneity judgment rule: the coefficient of variation more levels off to zero, sample mixing is more even.Incorporation time is shorter, and coefficient of variation fluctuation is larger, and representative mixing is more uneven.When the coefficient of variation is less than 10%, this research thinks that sample mixing is more even.

The coefficient of variation of methyl violet distribution in table 1, different incorporation times point different loci mixed-powder

Time (min)	10	14	18	22
					Coefficient of variation CV (%)	2.8	3.3	3.1	2.7

As shown in table 1, the sample of the present embodiment is when incorporation time is 10,14,18,22min, and coefficient of variation change is little, illustrates that mixed-powder mixes when mixing 10min.

Claims (7)

1. a detection method for heavy metal pollution of soil sample mixture homogeneity, is characterized in that, comprises the following steps:

(1) by methyl violet powder and the heavy metal pollution of soil sample mixing to be measured of some parts, mixed-powder is obtained;

(2) in mixed-powder, Stochastic choice different loci samples;

(3) mixed-powder of different loci dissolves with ethanol respectively, is configured to solution;

(4) light absorption value of described solution at 579nm place is measured respectively;

(5) by the coefficient of variation CV of methyl violet distribution in following formulae discovery different loci mixed-powder;

$\mathrm{CV}=S/\stackrel{\&OverBar;}{x}\&times;100\%$

S gets by whole site the standard deviation of light absorption value corresponding to mixed-powder, get by whole site the average of light absorption value corresponding to mixed-powder.

2. the detection method of heavy metal pollution of soil sample mixture homogeneity as claimed in claim 1, it is characterized in that, the granularity of described methyl violet powder and heavy metal pollution of soil sample to be measured is not more than 150 μm.

3. the detection method of heavy metal pollution of soil sample mixture homogeneity as claimed in claim 1, is characterized in that, before mixing, described methyl violet powder and heavy metal pollution of soil sample to be measured are by 100 mesh sieves.

4. the detection method of heavy metal pollution of soil sample mixture homogeneity as claimed in claim 1, it is characterized in that, in step (1), the weight ratio of described methyl violet powder and heavy metal pollution of soil sample total to be measured is 0.025 ~ 0.050:1000.

5. the detection method of heavy metal pollution of soil sample mixture homogeneity as claimed in claim 1, it is characterized in that, in step (1), the time of described mixing is 10 ~ 22min.

6. detection method as claimed in claim 1, it is characterized in that, in step (3), dissolution mechanism is ultrasonic dissolution.

7. detection method as claimed in claim 6, it is characterized in that, described ultrasonic dissolution condition is: the sound intensity of ultrasonic dissolution is 100W, and frequency is 20kHz, and the time is 30min.