CN113884643A - Method for evaluating phosphorus release risk of deep water reservoir surface sediment - Google Patents

Method for evaluating phosphorus release risk of deep water reservoir surface sediment Download PDF

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CN113884643A
CN113884643A CN202110955001.1A CN202110955001A CN113884643A CN 113884643 A CN113884643 A CN 113884643A CN 202110955001 A CN202110955001 A CN 202110955001A CN 113884643 A CN113884643 A CN 113884643A
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phosphorus
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李一平
朱雅
魏尧
黄亚男
张海阔
周玉璇
程月
潘泓哲
刘斯璇
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Hohai University HHU
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Abstract

The invention discloses a method for evaluating phosphorus release risk of deep water reservoir surface sediment, which mainly comprises the following steps: measuring the water depth, the water temperature and the dissolved oxygen concentration of the reservoir sampling point; collecting a sediment in-situ sample; measuring the porosity of the sediment and the available phosphorus concentration of the sediment; and calculating phosphorus ion diffusion flux at the sediment-water interface, the contribution rate of phosphorus ion diffusion to the overlying water and the potential energy index (APE) of the reservoir, and comprehensively evaluating the endogenous phosphorus release risk of the surface sediment based on the contribution rate of phosphorus ion diffusion to the overlying water, the APE (reservoir thermal stratification stability) and the dissolved oxygen concentration (bottom anoxic state) of the bottom layer of the sampling point. The method combines field monitoring and indoor simulation, estimates the release potential of endogenous phosphorus of the surface sediment and the contribution rate of the release potential to the concentration of phosphorus of overlying water, considers the stability of the unique seasonal heat layered structure of the reservoir, estimates the influence risk of the release of the sediment phosphorus on the eutrophication of the water body, and provides scientific basis for the water environment protection and treatment of the deep reservoir in China.

Description

Method for evaluating phosphorus release risk of deep water reservoir surface sediment
Technical Field
The invention belongs to the field of lake and reservoir sediment water environment control, and particularly relates to a method for evaluating phosphorus release risks of deep water reservoir surface sediment.
Background
According to the statistical data of the first national water conservancy general survey bulletin, the quantity of the reservoirs (98002) in China is about 34 times that of the lakes (2865), the reservoirs exceeding 1/3 are responsible for urban water supply sources, but the deep water reservoirs generally have water quality deterioration phenomena of eutrophication, black and odorous water and the like in different degrees in the last decade, and the water quality safety of the drinking water of the reservoirs is threatened. Phosphorus is one of the important limiting factors for lake and reservoir eutrophication, and endogenous phosphorus pollution of sediment is the leading cause of reservoir eutrophication of water source areas at the present stage. The sediment-water interface is an important place for carrying out material exchange between the substrate and the overlying water, and the environmental conditions of the interface, such as water depth, temperature, dissolved oxygen and the like, can obviously influence the sediment phosphorus migration and conversion process.
Seasonal thermal stratification is an important characteristic of deep water reservoirs compared with shallow lakes, and the existence of a thermocline obstructs the transfer of dissolved oxygen of water bodies at the surface and bottom layers and the dual action of biochemical oxygen consumption of sediments leads the phenomenon of bottom layer oxygen deficiency to be ubiquitous. The anoxic condition of the water body can accelerate the release of the sediment phosphorus to the overlying water, so that the phosphorus is enriched at the bottom layer of the reservoir, once the thermal layered structure of the deep water reservoir is unstable, the high-concentration phosphorus is exchanged to the surface layer and provides nutrient salt for the growth of plankton such as algae, the accumulation and death of the algae are aggravated, and the obvious adverse effect is caused on the water ecological system of the reservoir. In the prior art, the method for evaluating the influence of wind wave disturbance on the water environment by sediment resuspension is more, most of the methods are concentrated on evaluation of endogenous phosphorus release risks of sediments in shallow lakes, but the method for comprehensively evaluating the phosphorus release risks of sediments on the surface layer of the reservoir from the aspects of reservoir thermal stratification stability and endogenous phosphorus release of sediments is less.
Disclosure of Invention
Aiming at the defects in the existing method, the invention provides a method for evaluating the phosphorus release risk of the sediment on the surface layer of the deep water reservoir, which can comprehensively evaluate the influence of thermal stratification, stabilization and extinction on the release of endogenous phosphorus in the sediment and provide a scientific basis for preventing and controlling the eutrophication of the deep water reservoir.
In order to solve the technical problems, the technical scheme adopted by the invention is as follows: the method for evaluating the phosphorus release risk of the deep water reservoir surface sediment comprises the following steps:
s1: measuring the water depth, the water temperature and the dissolved oxygen concentration of the water body sampling point of the reservoir;
s2: collecting the in-situ sediment of the sampling point to obtain a sediment sample, and storing the sediment sample in the same temperature environment as the bottom layer of the sampling point;
s3: controlling the initial dissolved oxygen concentration in the overlying water of the sediment sample to be consistent with the bottom dissolved oxygen concentration of the sampling point, measuring the water content of the surface sample of the sediment sample, and calculating the porosity of the sediment according to the water content; and measuring and calculating the phosphorus concentration of the flat DGT effective state of the sediment sample, wherein the DGT is a thin film diffusion gradient technology;
s4: calculating phosphorus ion diffusion flux at a sediment-water interface according to the sediment porosity and the effective phosphorus concentration of the flat-plate DGT;
s5: calculating the contribution rate of phosphorus ion diffusion to overlying water according to the diffusion flux and the water depth of the sampling point, wherein the contribution rate of phosphorus ion diffusion to overlying water represents the influence degree of endogenous phosphorus migration diffusion of the sediment on the overlying water body;
s6: calculating a potential energy index APE of the reservoir according to the water depth and the water temperature of the sampling point; determining the thermal stratification stability of the reservoir according to the APE, and determining the bottom layer oxygen deficiency state according to the dissolved oxygen concentration of the bottom layer of the sampling point;
s7: and comprehensively evaluating the endogenous phosphorus release risk of the surface sediment based on the contribution rate of phosphorus ion diffusion to overlying water, the thermal stratification stability of the reservoir and the anoxic state of the bottom layer.
In some embodiments, step S3 includes:
s31, controlling the initial dissolved oxygen concentration of the sediment sample in the overlying water to be consistent with the dissolved oxygen concentration of the bottom layer of the sampling point, and standing in a dark place;
s32, vertically inserting the flat-plate DGT subjected to the nitrogen and oxygen filling and removing treatment into a sediment sample, and keeping the flat-plate DGT for 3-5 cm in water on the sediment sample;
s33, taking out and marking the position of a sediment-water interface of the sediment sample, washing the surface of the flat-plate DGT by deionized water, cutting a fixed film in the flat-plate DGT into a plurality of strip-shaped slices, measuring the water content of a sample with the thickness of 5cm on the surface layer of the sediment sample, and calculating the porosity of the sediment according to the water content;
and S34, respectively extracting the strip-shaped slices for more than 16 hours by using alkali, collecting extracting solution, measuring the phosphorus concentration in the extracting solution, and calculating to obtain the phosphorus concentration of the flat-plate DGT in the effective state.
Further, calculating the porosity of the sediment according to the water content, and the method comprises the following steps:
φ＝wρs/[(1-w)ρw+wρs]
where φ is sediment porosity, w represents water content, ρwRepresenting the average density, p, of a body of watersRepresenting the average density of the deposit.
Further, step S34 includes:
calculating the accumulation amount M of the phosphorus absorbed by the fixed film according to the measured phosphorus concentration in the extracting solution:
M＝CeVe/fe
wherein, CeIs the phosphorus concentration of the extract VeIs volume of extract, feExtracting phosphorus;
calculating the phosphorus concentration C of the flat-plate DGT in the effective state according to the cumulant MDGT：
CDGT＝MΔg/DAt
Wherein Δ g is the thickness of the diffusion layer, D is the diffusion coefficient of phosphorus in the diffusion layer, A is the area of each strip-shaped slice, and t is the standing time of the flat-plate DGT.
In some embodiments, the water temperature and dissolved oxygen concentration in step S1 are monitored every 0.5 meters vertically along the sampling point.
In some embodiments, the phosphorus ion diffusion flux at the deposit-water interface in step S4 is calculated as follows:
Figure BDA0003219897010000031
where φ is deposit porosity, CDGTIs the phosphorus concentration of the flat-plate DGT in an effective state,
Figure BDA0003219897010000032
is a gradient of the concentration of phosphorus ions at the sediment-water interface, DsIs the molecular diffusion coefficient of phosphorus in the deposit.
Further, the gradient of the concentration of phosphorus ions at the sediment-water interface is determined according to the effective phosphorus concentration C of the flat DGT of the sedimentDGTAnd performing linear fitting on the relation curve of the depths corresponding to the strip-shaped slices to obtain the depth-to-depth relation curve. Molecular diffusion coefficient D of phosphorus in said depositsUsually based on the diffusion coefficient D of phosphorus in dilute solution0Derived, empirical relationships are as follows:
Ds＝φD0(φ＜0.7)
Ds＝φ2D0(φ＞0.7)
D0＝7.34+0.16(Tem-25)
where Tem is the actual temperature of the overburden water and phi is the deposit porosity.
In some embodiments, the contribution rate a of phosphorus ion diffusion to overburden water in step S5 is calculated as follows:
a＝JT/hCa
wherein J is the diffusion flux of phosphorus ions at the sediment-water interface, and T is the retention time of water bodyH is the depth of the sampling point water, CaIs the average concentration of ions in the overlying water.
The water body residence time calculation formula is as follows:
T＝V/Q
wherein V is the effective volume of the reservoir, and Q is the runoff of the moon entering the reservoir.
In some embodiments, the calculation formula of the potential energy index APE of the reservoir in step S6 is as follows:
Figure BDA0003219897010000041
in the formula, h is the depth of a sampling point, rho is the density of water bodies at different depths, and the density of the water bodies is obtained by performing density conversion according to the actually measured water temperature at the corresponding depth; rho*Is the average water density of the reservoir in the vertical direction, and g is the gravity acceleration.
In some embodiments, the contribution of phosphorus ion diffusion to the overlying water characterizes the extent to which the endogenous phosphorus migration diffusion of the deposit affects the overlying water body, including: when the contribution rate is positive, the sediment phosphorus is released from interstitial water to overlying water, and the larger the value is, the larger the influence is; when the contribution rate is negative, phosphorus in the overlying water migrates to the sediment and precipitates, and the influence of endogenous phosphorus in the sediment on the water body is extremely small.
Determining the thermal stratification stability of the reservoir according to the APE, comprising: 0.05<APE<0.9J/m3Is defined as the stratified formation or weakening phase, APE>0.9J/m3Defined as stratified stationary phase, APE<0.05J/m3The period of time (c) is defined as the complete mixing period.
Determining the bottom layer oxygen deficiency state according to the dissolved oxygen concentration of the bottom layer of the sampling point, comprising: hypoxic states are classified into three categories: hypoxia: the dissolved oxygen concentration DO is less than or equal to 2 mg/L; severe hypoxia: the dissolved oxygen concentration DO is less than or equal to 1 mg/L; anaerobic reaction: the dissolved oxygen concentration DO is less than or equal to 0.2 mg/L.
Furthermore, the sampling points are selected in consideration of reservoir functions, natural geographical characteristics of reservoir areas, distribution of warehousing runoff and distribution of water intake and other factors.
Further, the flat-bed DGT was left for 24 hours in the step S3, and the temperature of the overlaying water was measured every 4 hours.
Further, the flat-plate DGT device in step S3 mainly comprises a fixed membrane, a diffusion membrane and a filtration membrane, and is subjected to nitrogen and oxygen filling treatment before use, specifically: and immersing the flat-plate DGT in a plastic container of 0.01M NaCl solution, continuously introducing high-purity nitrogen for more than 16 hours, packaging, sealing and opening when the flat-plate DGT is used.
Further, in the step S3, the effective length of the flat-plate DGT is 15cm, and 10-12 cm is vertically inserted into the sediment sample in the operation process.
The invention achieves the following beneficial effects: the scheme combines field monitoring and indoor simulation, estimates the release potential of endogenous phosphorus of surface sediment and the contribution rate of the potential to the concentration of phosphorus of overlying water, reasonably considers the stability of the unique seasonal heat stratification structure of the reservoir, estimates the influence risk of the release of the endogenous phosphorus of the sediment on the eutrophication of the water body, and judges whether the release of the endogenous phosphorus of the sediment can influence the eutrophication of the surface water body by determining the duration of the heat stratification of the deep water reservoir, so that reasonable regulation and control time and measures are selected, and the cost of the eutrophication control of the reservoir is reduced.
Drawings
FIG. 1 is a schematic position diagram of 2 sampling points of surface sediments of a hail reservoir selected by the invention;
FIG. 2 is a schematic diagram of vertical water temperature and dissolved oxygen of a water body of a hail reservoir at different time periods at 2 sampling points according to the determination method of the invention;
fig. 3 is a schematic diagram of effective phosphorus concentration of sediment profiles of hail reservoirs at different periods at 2 sampling points according to the determination method of the invention.
Detailed Description
The method for evaluating the risk of releasing phosphorus from the deep water reservoir surface sediment provided by the invention is described in detail with reference to specific embodiments.
The method for evaluating the phosphorus release risk of the deep water reservoir surface sediment comprises the following steps:
s1: determining physical parameters of a reservoir water body: the research object of the embodiment is a deep water reservoir-hail reservoir in south-west city of Guangxi, 2 sampling points are selected according to the natural geographical features of the hail reservoir, as shown in figure 1, at different periods, the vertical water depth, the water temperature and the Dissolved Oxygen (DO) concentration of the sampling points (TB1 and TB2) are measured by a multi-parameter water quality monitor, and the data result is shown in figure 2;
s2: collecting in-situ sediment samples: collecting the in-situ sediment of the sampling point by using a gravity mud sampler, and hermetically storing the sediment sample in an environment with the same temperature as the bottom layer of the sampling point, namely the water temperature of the bottom layer measured by a multi-parameter water quality monitor;
s3: and (3) determining the available phosphorus concentration of the sediment:
firstly, controlling the initial dissolved oxygen concentration of the sediment sample in the overlying water to be consistent with the bottom layer concentration of the sampling point by a nitrogen or air introducing method, namely, controlling the bottom layer dissolved oxygen measured by a multi-parameter water quality monitor to stand away from light;
vertically inserting the flat-plate DGT subjected to the nitrogen and oxygen filling and removing treatment into the sediment and standing for 24 hours, wherein the effective length of the flat-plate DGT is 15cm, and vertically inserting 10-12 cm into the sediment sample in the operation process; the nitrogen filling and deoxidation treatment comprises the following specific steps: immersing the flat-plate DGT in a plastic container of 0.01M NaCl solution, and continuously introducing high-purity nitrogen for more than 16 hours;
taking out and marking the position of a sediment-water interface of the sediment sample, and washing sediment residual particles on the surface of the flat-plate DGT by deionized water; and measuring the water content of the sample with the thickness of 5cm on the surface layer of the sediment, and taking the sample W of the sediment0Dried at 105 ℃ and weighed again as W1And g, calculating the water content w according to the following formula:
w＝(W0-W1)/W0 (1)
and then calculating the porosity phi according to the w, wherein the calculation formula is as follows:
φ＝wρs/[(1-w)ρw+wρs] (2)
where ρ iswIndicating waterThe average density of the body is 1.0g/cm3，ρsThe average density of the sediment is expressed and is 2.65g/cm3。
The flat-plate DGT device mainly comprises a fixed membrane, a diffusion membrane and a filter membrane; after the surface is washed clean, cutting a fixed film along the flat-plate DGT exposure window, placing the fixed film on a group of ceramic slices, and cutting the fixed film into a plurality of strip-shaped slices (20mm multiplied by 5mm) in a one-dimensional vertical direction; (b) respectively putting the strip-shaped slices into a centrifuge tube, adding 2mL of 1.0M NaOH extracting solution to ensure that the fixed membrane is completely immersed, standing and extracting at room temperature for more than 16h, measuring the phosphorus concentration in the extracting solution by adopting a molybdenum blue colorimetric method, and calculating to obtain the effective phosphorus concentration C of the flat-plate DGTDGTThereby obtaining the phosphorus concentration C of the flat DGT active stateDGTThe curve of the depth dependence of the strip-shaped slice, as shown in fig. 3; wherein, CDGTThe calculation formula of (2) is as follows:
firstly, calculating the cumulative quantity M of the phosphorus absorbed by the fixed film according to the phosphorus concentration measured in the extracting solution, wherein the calculation formula of M is as follows:
M＝CeVe/fe (3)
wherein, CeIs the phosphorus concentration of the extract VeIs volume of extract, feExtracting phosphorus, and the value is 0.95;
then calculating the phosphorus concentration C of the flat-plate DGT in the effective state according to the MDGTThe calculation formula is as follows:
CDGT＝MΔg/DAt (4)
wherein Δ g is the thickness of the diffusion layer and is 0.8mm, D is the diffusion coefficient of phosphorus in the diffusion layer, and A is the area of each strip-shaped slice and is 1cm2And t is the placement time of the DGT device, and the value is 86400 s.
S4: sediment-water interface phosphorus ion diffusion flux calculation: the sediment-water interface phosphorus ion diffusion flux calculation formula is as follows:
Figure BDA0003219897010000071
where phi is the porosity of the deposit,
Figure BDA0003219897010000072
is the gradient of the concentration of phosphorus ions at the sediment-water interface, DsIs the molecular diffusion coefficient of phosphorus in the deposit
The phosphorus ion concentration gradient is based on the available phosphorus concentration C of the sedimentDGTLinear fitting is carried out on a relation curve (figure 3) of the corresponding depths of the strip-shaped slices; molecular diffusion coefficient D of phosphorus in said depositsUsually based on the diffusion coefficient D of phosphorus in dilute solution0Derived, empirical relationships are as follows:
Figure BDA0003219897010000073
D0＝7.34+0.16(Tem-25) (7)
wherein Tem is the actual temperature of the overlying water, namely the water temperature of the bottommost layer measured by the multi-parameter water quality monitor, and phi is the porosity of the sediment.
S5: the contribution rate of phosphorus ion diffusion to overlying water was calculated: according to the diffusion flux and the water depth of the sampling point, calculating the contribution rate of phosphorus ion diffusion to overlying water, wherein the calculation formula is as follows:
a＝JThCa (8)
wherein J is the diffusion flux of phosphorus ions at the sediment-water interface, T is the retention time of the water body, h is the water depth, CaIs the average concentration of ions in the overlying water.
The water body residence time calculation formula is as follows:
T＝VQ (9)
wherein V is the effective volume of the reservoir, and Q is the runoff of the moon entering the reservoir.
S6: calculating a potential energy index APE of the reservoir: according to the physical parameters of the water body, calculating a potential energy index APE of the reservoir, determining the thermal stratification stability degree and the bottom layer anoxic state of the reservoir, and comprehensively evaluating the endogenous phosphorus release risk of surface sediments and the influence degree of the endogenous phosphorus release risk on the water quality of the reservoir area, wherein the calculation formula is as follows:
Figure BDA0003219897010000081
in the formula, h is the depth of a sampling point, rho is the density of water bodies in different depths, and the density is obtained by density conversion according to the actually measured water temperature of the corresponding depth*Is the average water density of the reservoir in the vertical direction, and g is the gravity acceleration.
The method for judging the thermal stratification stability of the deep water reservoir by using the potential energy index APE of the reservoir comprises the following steps: 0.05<APE<0.9J/m3Is defined as the stratified formation or weakening phase, APE>0.9J/m3Defined as stratified stationary phase, APE<0.05J/m3The period of time (d) is defined as the complete mixing period;
the effective state P concentrations of the sediments at the TB1 sampling points and the TB2 sampling points are 0.003-0.073 mg/L and 0.003-0.041 mg/L respectively, the effective state P of the sediments at the TB1 sampling points and the TB2 sampling points show the release trend of the sediments into overlying water, and the diffusion flux of the effective state P of the sediments at the TB1 sampling points shows Day14 (0.029 mg/(m)2·d)]<Day1[0.095mg/(m2·d)]<Day34[0.101mg/(m2·d)]The TB2 sampling point also showed Day14[0.026 mg/(m)2·d)]<Day1[0.037mg/(m2·d)]<Day34[0.090mg/(m2·d)]The trend of (c).
The contribution rates of sediment phosphorus of the TB1 sampling points and the TB2 sampling points to the overlying water are positive values (table 2), and the bottom layers of the two sampling points are in an anoxic state at the Day1, so that the sediment endogenous phosphorus of the two sampling points is always released from interstitial water to the overlying water, and the potential energy index APE value of the reservoir (table 3) is combined, so that the TB2 sampling point has a stable thermal layered structure at the Day1, the sediment phosphorus is difficult to migrate to the surface layer after being released to the overlying water body, the influence on the surface water body of the reservoir is small, the eutrophication degree of the surface water body cannot be increased, on the contrary, the TB1 sampling point water body thermal layered structure is weak at the Day1, the water body is vertically mixed at the Day14, the sediment endogenous phosphorus is brought to the surface layer, and the eutrophication degree of the surface water body is increased. The deep water reservoir has large space difference, and the thermal stratification failure time of different areas is asynchronous, so when the prevention and control measures are adopted for the endogenous phosphorus in the sediments of different areas of the reservoir, the starting time of the prevention and control measures (such as underwater aeration, desilting and the like) can be accurately controlled according to the method, the economic cost is reduced, and the release of the endogenous phosphorus in the sediments can be effectively reduced.
TABLE 1 diffusion coefficient of phosphorus ions in DGT diffusion layer
Temperature (. degree.C.) Diffusion coefficient (. times.10)-6cm2/s) Temperature (. degree.C.) Diffusion coefficient (. times.10)-6cm2/s)
1 3.20 16 5.31
2 3.32 17 5.47
3 3.45 18 5.63
4 3.57 19 5.80
5 3.70 20 5.97
6 3.84 21 6.14
7 3.97 22 6.32
8 4.11 23 6.50
9 4.25 24 6.68
10 4.39 25 6.86
11 4.54 26 7.05
12 4.69 27 7.23
13 4.84 28 7.43
14 4.99 29 7.62
15 5.15 30 7.82
TABLE 2 sediment-water interface phosphorus ion diffusion flux and its contribution to overlying water
Figure BDA0003219897010000091
TABLE 3 latent potential energy index APE values of reservoirs at different periods
Figure BDA0003219897010000092
The above description is only a preferred embodiment of the present invention, and the present invention is not limited to the content of the embodiment. It will be apparent to those skilled in the art that various changes and modifications can be made within the technical scope of the present invention, and any changes and modifications made are within the protective scope of the present invention.

Claims (10)

1. The method for evaluating the phosphorus release risk of the deep water reservoir surface sediment is characterized by comprising the following steps of:
s1: measuring the water depth, the water temperature and the dissolved oxygen concentration of the water body sampling point of the reservoir;
s2: collecting the in-situ sediment of the sampling point to obtain a sediment sample, and storing the sediment sample in the same temperature environment as the bottom layer of the sampling point;
s3: controlling the initial dissolved oxygen concentration in the overlying water of the sediment sample to be consistent with the bottom dissolved oxygen concentration of the sampling point, measuring the water content of the surface sample of the sediment sample, and calculating the porosity of the sediment according to the water content; and measuring and calculating the phosphorus concentration of the flat DGT effective state of the sediment sample, wherein the DGT is a thin film diffusion gradient technology;
s4: calculating phosphorus ion diffusion flux at a sediment-water interface according to the sediment porosity and the effective phosphorus concentration of the flat-plate DGT;
s5: calculating the contribution rate of phosphorus ion diffusion to overlying water according to the diffusion flux and the water depth of the sampling point, wherein the contribution rate of phosphorus ion diffusion to overlying water represents the influence degree of endogenous phosphorus migration diffusion of the sediment on the overlying water body;
s6: calculating a potential energy index APE of the reservoir according to the water depth and the water temperature of the sampling point; determining the thermal stratification stability of the reservoir according to the APE, and determining the bottom layer oxygen deficiency state according to the dissolved oxygen concentration of the bottom layer of the sampling point;
s7: and comprehensively evaluating the endogenous phosphorus release risk of the surface sediment based on the contribution rate of phosphorus ion diffusion to overlying water, the thermal stratification stability of the reservoir and the anoxic state of the bottom layer.
2. The method for evaluating the risk of phosphorus release from surface sediments in deep water reservoirs of claim 1, wherein step S3 comprises:
s31, controlling the initial dissolved oxygen concentration of the sediment sample in the overlying water to be consistent with the dissolved oxygen concentration of the bottom layer of the sampling point, and standing in a dark place;
s32, vertically inserting the flat-plate DGT subjected to the nitrogen and oxygen filling and removing treatment into a sediment sample, and keeping the flat-plate DGT for 3-5 cm in water on the sediment sample;
s33, taking out and marking the position of a sediment-water interface of the sediment sample, washing the surface of the flat-plate DGT by deionized water, cutting a fixed film in the flat-plate DGT into a plurality of strip-shaped slices, measuring the water content of a sample with the thickness of 5cm on the surface layer of the sediment sample, and calculating the porosity of the sediment according to the water content;
and S34, respectively extracting the strip-shaped slices for more than 16 hours by using alkali, collecting extracting solution, measuring the phosphorus concentration in the extracting solution, and calculating to obtain the phosphorus concentration of the flat-plate DGT in the effective state.
3. The method for evaluating the phosphorus release risk of the deep water reservoir surface sediment according to claim 2, wherein the sediment porosity is calculated according to the water content, and the method comprises the following steps:
φ＝wρs/[(1-w)ρw+wρs]
where φ is sediment porosity, w represents water content, ρwRepresenting the average density, p, of a body of watersRepresenting the average density of the deposit.
4. The method for evaluating the risk of phosphorus release from surface sediments in deep water reservoirs of claim 2, wherein step S34 comprises:
calculating the accumulation amount M of the phosphorus absorbed by the fixed film according to the measured phosphorus concentration in the extracting solution:
M＝CeVe/fe
wherein, CeIs the phosphorus concentration of the extract VeIs volume of extract, feExtracting phosphorus;
calculating the phosphorus concentration C of the flat-plate DGT in the effective state according to the cumulant MDGT：
CDGT＝MΔg/DAt
Wherein Δ g is the thickness of the diffusion layer, D is the diffusion coefficient of phosphorus in the diffusion layer, A is the area of each strip-shaped slice, and t is the standing time of the flat-plate DGT.
5. The method for assessing the risk of phosphorus release from surface sediments in deepwater reservoirs as claimed in claim 1, wherein said water temperature and dissolved oxygen concentration in step S1 are monitored every 0.5 meters vertically along the sampling point.
6. The method for evaluating phosphorus release risk of surface sediment of deep water reservoir of claim 1, wherein the calculation formula of phosphorus ion diffusion flux at the sediment-water interface in step S4 is as follows:
Figure FDA0003219890000000021
where φ is deposit porosity, CDGTIs the phosphorus concentration of the flat-plate DGT in an effective state,
Figure FDA0003219890000000022
is a gradient of the concentration of phosphorus ions at the sediment-water interface, DsIs the molecular diffusion coefficient of phosphorus in the deposit.
7. The method for assessing phosphorus release risk of surface sediments in deepwater reservoirs as claimed in claim 6, wherein the phosphorus ion concentration gradient of the sediment-water interface is determined according to the phosphorus concentration C of the effective state of the flat DGT of the sedimentDGTAnd performing linear fitting on the relation curve of the depths corresponding to the strip-shaped slices to obtain the depth-to-depth relation curve.
8. The method for evaluating the risk of phosphorus release from surface sediments of deep water reservoirs according to claim 1, wherein the contribution rate a of phosphorus ion diffusion to overlying water in step S5 is calculated as follows:
a＝JT/hCa
in the formula, J is the diffusion flux of phosphorus ions at the sediment-water interface, T is the retention time of the water body, h is the depth of the sampling point water, CaIs the average concentration of ions in the overlying water.
9. The method for evaluating the phosphorus release risk of the surface sediment of the deep water reservoir as claimed in claim 1, wherein the calculation formula of the potential energy index APE of the deep water reservoir in the step S6 is as follows:
Figure FDA0003219890000000031
in the formula, h is the depth of a sampling point, rho is the density of water bodies at different depths, and the density of the water bodies is obtained by performing density conversion according to the actually measured water temperature at the corresponding depth; rho*Is the average water density of the reservoir in the vertical direction, and g is the gravity acceleration.
10. The method for evaluating the risk of phosphorus release from surface sediments in deep water reservoirs according to claim 1,
determining the thermal stratification stability of the reservoir according to the APE, comprising: 0.05<APE<0.9J/m3Is defined as the stratified formation or weakening phase, APE>0.9J/m3Defined as stratified stationary phase, APE<0.05J/m3The period of time (d) is defined as the complete mixing period;
and/or determining the bottom layer oxygen-poor state according to the dissolved oxygen concentration of the bottom layer of the sampling point, wherein the determining comprises the following steps: hypoxia: the dissolved oxygen concentration DO is less than or equal to 2 mg/L; severe hypoxia: the dissolved oxygen concentration DO is less than or equal to 1 mg/L; anaerobic reaction: the dissolved oxygen concentration DO is less than or equal to 0.2 mg/L.
And/or the contribution rate of phosphorus ion diffusion to the overlying water characterizes the influence degree of the endogenous phosphorus migration diffusion of the sediment on the overlying water body, and the influence degree comprises the following steps: when the contribution rate is positive, the sediment phosphorus is released from interstitial water to overlying water, and the larger the value is, the larger the influence is; when the contribution rate is negative, phosphorus in the overlying water migrates to the sediment and precipitates, and the influence of endogenous phosphorus in the sediment on the water body is extremely small.
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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114662422A (en) * 2022-04-02 2022-06-24 中国水利水电科学研究院 Construction method of thermal stratification reservoir thermocline dissolved oxygen prediction model

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN203772829U (en) * 2014-03-05 2014-08-13 同济大学 Device for laboratory for simulating nitrogen and phosphorus release of water body sediments
CN104048930A (en) * 2013-03-12 2014-09-17 中国科学院南京地理与湖泊研究所 Synchronization acquisition method of active phosphorus and iron in deposit
CN104360025A (en) * 2014-11-21 2015-02-18 中国环境科学研究院 DGT-DIFS measurement method for phosphorus release characteristics of anaerobic surface sediments in lake
CN107121527A (en) * 2017-05-03 2017-09-01 中国环境科学研究院 The appraisal procedure and device of a kind of lake sediment covering material control effect
CN110162905A (en) * 2019-05-29 2019-08-23 河海大学 A kind of large-scale shallow water lake model and its construction method based on internal loading

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104048930A (en) * 2013-03-12 2014-09-17 中国科学院南京地理与湖泊研究所 Synchronization acquisition method of active phosphorus and iron in deposit
CN203772829U (en) * 2014-03-05 2014-08-13 同济大学 Device for laboratory for simulating nitrogen and phosphorus release of water body sediments
CN104360025A (en) * 2014-11-21 2015-02-18 中国环境科学研究院 DGT-DIFS measurement method for phosphorus release characteristics of anaerobic surface sediments in lake
CN107121527A (en) * 2017-05-03 2017-09-01 中国环境科学研究院 The appraisal procedure and device of a kind of lake sediment covering material control effect
CN110162905A (en) * 2019-05-29 2019-08-23 河海大学 A kind of large-scale shallow water lake model and its construction method based on internal loading

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
卢金锁 等: "热分层对水库水质的季节性影响———以西安黑河水库为例*", 《湖泊科学》 *
朱雅 等: "南方水库季节性热分层消亡对沉积物铁和磷迁移的影响———以南宁市天雹水库为例", 《湖泊科学》 *
马迎群 等: "嘉兴市北部湖荡区沉积物磷释放通量估算及影响因素研究", 《 环境工程技术学报 》 *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114662422A (en) * 2022-04-02 2022-06-24 中国水利水电科学研究院 Construction method of thermal stratification reservoir thermocline dissolved oxygen prediction model

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