Soil heavy metal exogenous pollution early warning method based on material flow balance

Abstract

A soil heavy metal exogenous pollution early warning method based on material flow balance relates to the technical field of soil heavy metal early warning, and specifically comprises the following steps: detection: detecting heavy metals in a water body and heavy metals in the atmosphere in real time, and detecting heavy metal pollution caused by human factors such as chemical fertilizers and livestock and poultry manure; data calculation: estimating the heavy metal input amount through a scientific calculation method, and calculating the annual accumulation rate of the heavy metal; and alarming: comparing the calculated heavy metal content of the soil polluted by the external source with a limit value of 'Soil Environment Quality Agricultural Land Soil Pollution Risk Management and Control Standard', and sending out an early warning signal when the content exceeds the standard limit value. According to the invention, the problem that comprehensive accumulation influence of water, atmosphere and heavy metals is not fully considered in the prior art is solved, and effective monitoring and early warning of heavy metal exogenous pollution of the black land are realized.

Description

Technical Field

[0001] The present invention relates to the technical field of soil heavy metal early warning, and in particular to a soil heavy metal exogenous pollution early warning method based on material flow balance. Background Art

[0002] Black soil is a unique treasure given by nature to mankind. It has the characteristics of loose texture, high fertility, and strong fertilizer supply capacity. It is called the "giant panda" in the soil. It is the cornerstone of the Northeast granary and the land foundation of Northeast agriculture. In recent years, with the acceleration of urbanization and the continuous emergence of problems such as improper land cultivation, heavy metal elements have accumulated in black soil. The pollution of heavy metals in the soil may affect the normal function of the soil, cause pollution of the food chain, and threaten humans and the environment through enrichment in the human body. Therefore, the problem of heavy metal pollution in black soil has received widespread attention from scholars. In order to protect black soil resources, steadily restore and improve the basic soil fertility of black soil, promote the sustainable use of resources, maintain ecological balance, and ensure national food security.

[0003] Many domestic scholars have conducted research on early warning of heavy metal pollution in soil. Some scholars have proposed a "general concept model of heaven, earth and man" for early warning of heavy metal pollution in farmland in China. Early warning of heavy metal pollution in farmland needs to be based on the causes and indicators of heavy metal pollution. Since it is difficult to determine the pollutants, driving forces and environmental factors of any unit in space, the relationship between "material driving force and environmental factors" of heavy metal pollution in farmland is transformed into a "general concept model of heaven, earth and man", that is, heavy metal pollution in farmland is mainly affected by the three major factors of "heaven, earth and man". In this way, the direct prediction of heavy metals in farmland can also be transformed into the division of driving forces of heavy metal pollution in farmland, that is, early warning. "General concept model of heaven, earth and man". Some scholars have established a comprehensive early warning system for heavy metal pollution at the national, provincial and county levels according to the administrative level, including early warning units, early warning purposes, early warning indicators, and early warning value calculation methods. There are many studies on early warning of heavy metals in soil, most of which are based on the existing content of heavy metals in the soil, without considering the comprehensive cumulative impact of water, atmosphere and heavy metals. There are also few studies on early warning technology for exogenous pollution of heavy metals in black soil. Summary of the invention

[0004] In order to solve the problem that the soil heavy metal early warning method in the prior art fails to fully consider the comprehensive cumulative impact of water, atmosphere and heavy metals, the present invention provides a soil heavy metal exogenous pollution early warning method based on material flow balance, and the specific technical scheme is as follows: A soil heavy metal exogenous pollution early warning method based on material flow balance comprises the following steps: 1. Testing: The heavy metal concentration in the crop irrigation water is detected by the heavy metal detection method in water; The concentration of heavy metals in the atmosphere is detected by the LB-ZJ200 atmospheric heavy metal online analyzer; Detect heavy metal concentrations in fertilizers and livestock and poultry manure; 2. Data calculation: ① Calculate the SI of heavy metals introduced into the soil by irrigation based on the detected heavy metal concentrations; ② Calculate the heavy metal content Q brought into the soil by atmospheric deposition based on the detected heavy metal concentration; ③ Calculate the heavy metal content FI brought into the soil by fertilization based on the detected heavy metal concentration; ④ Calculate the heavy metal content LMP brought into the soil by livestock and poultry manure based on the detected heavy metal concentration; ⑤ Calculate the accumulation of heavy metals in soil SC based on SI, Q, FI and LMP; ⑥ Calculate the annual accumulation rate γ of heavy metals according to SC; the calculation formula of the annual accumulation rate γ of heavy metals is γ =SC·ρ^-1·h^-1·π, where SC is the accumulation of heavy metals in the soil, ρ represents the soil bulk density, h represents the soil layer thickness, and π represents the unit conversion coefficient; ⑦ Calculate the content of heavy metals in the soil contaminated by exogenous sources WY according to γ; the calculation formula of the content of heavy metals in the soil contaminated by exogenous sources WY is WY=γ+BD, where γ represents the annual accumulation rate of heavy metals, and BD represents the initial content of heavy metals in the soil; 3. Alarm: Compare the calculated heavy metal content WY of the soil contaminated by external sources with the limit value of the "Soil Environmental Quality Agricultural Land Soil Pollution Risk Control Standard". When WY exceeds the standard limit, an early warning signal will be issued.

[0005] Furthermore, the calculation formula for the heavy metal content SI brought into the soil by irrigation is SI=WC, where W represents the irrigation water volume of crops, and C represents the heavy metal concentration in the irrigation water of crops.

[0006] Furthermore, the calculation formula for the heavy metal content FI brought into the soil by fertilization is FI = CF, where C represents the heavy metal concentration in the fertilizer and F represents the annual fertilizer usage.

[0007] Furthermore, the calculation formula for the heavy metal content LMP brought into the soil by livestock and poultry manure is LMP = CRa / T, where C represents the heavy metal concentration in livestock and poultry manure, R represents the excretion coefficient of livestock and poultry manure, a represents the utilization rate of manure, and T represents the planting area of ​​crops.

[0008] Compared with the prior art, the present invention has the following advantages and features: The present invention firstly detects the heavy metal pollution caused by human factors such as water irrigation, atmospheric deposition, pesticide and fertilizer application in real time, then calculates and transmits the increment and accumulation of heavy metals brought into the soil by water irrigation, atmospheric deposition, pesticide and fertilizer application, and finally compares with the set standard threshold to realize the early warning of heavy metal pollution and prevent and control soil heavy metal pollution. This makes up for the deficiency of the prior art that only early warning is performed on the existing content of heavy metals in the soil. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 This is a logic module diagram of the present invention.

[0010] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. The other drawings obtained are all within the protection scope required by the present invention. DETAILED DESCRIPTION

[0011] A soil heavy metal exogenous pollution early warning method based on material flow balance, characterized in that it comprises the following steps: Step 1: Detection: The heavy metal concentration in the water used for crop irrigation is detected by the heavy metal detection method in water. The water used for crop irrigation contains heavy metals. Before crop irrigation, the heavy metals in the water are sampled and tested on site to analyze the heavy metal content. The heavy metal detection method in water is shown in Table 1.

[0012] Table 1: Detection methods for heavy metals in water The concentration of heavy metals in the atmosphere is detected by the LB-ZJ200 atmospheric heavy metal online analyzer. Atmospheric deposition can also cause heavy metal pollution to the soil. A detection analyzer is set up at the border of the black soil for 24-hour online monitoring.

[0013] LB-ZJ200 atmospheric heavy metal online analyzer is an independently developed online atmospheric heavy metal continuous monitor that integrates X-ray fluorescence nondestructive testing technology, β-ray absorption detection technology and air particulate matter automatic enrichment technology. It complies with the US EPA IO-3.3 standard method. It can not only monitor the mass concentration of air particulate matter, but also quantitatively analyze the elemental composition in the particulate matter at the same time. It can realize the monitoring of low-level lead, cadmium, chromium, arsenic and other heavy metals in air particulate matter and the coordinated measurement of PM concentration, unmanned and long-term automatic monitoring. LB-ZJ200 atmospheric heavy metal online analyzer adopts a precise constant current sampling system for sampling, accurately controls the collected air volume, and enriches the particulate matter in the air through the filter membrane. The beta-ray absorption method is used to detect the content of particulate matter enriched on the filter membrane to obtain the concentration of particulate matter in the air C1, in μg / m3; the X-ray fluorescence technology is used to detect the element content in the particulate matter to obtain the element concentration C2 in the air, in ng / m3; combining the measurement results of the particulate matter concentration and the element concentration in the air, the mass concentration of the element in the particulate matter C3=(C2 / C1)*103 (unit ppm) and the percentage content of the element in the particulate matter P=(C2 / C1)*10-3*100% can be obtained.

[0014] Detect heavy metal concentrations in fertilizers and livestock and poultry manure; Step 2: Data calculation: ① Calculate the heavy metal content SI brought into the soil by irrigation based on the detected heavy metal concentration; sewage irrigation has a long history. After long-term sewage irrigation, there has been obvious accumulation of heavy metals in the surface soil of sewage-irrigated farmland. In this paper, the sewage irrigation area is estimated according to the heavy metal concentration in the sewage irrigation water, and the non-sewage irrigation area is estimated according to the heavy metal concentration in the sewage irrigation water. The types of crops planted in the farmland system are mainly wheat, corn, rice, sorghum, oil crops and vegetables. The water requirement of each crop is referred to the relevant results in the literature, and the natural rainfall is deducted from the water requirement of each crop to obtain the actual irrigation water required by the crop.

[0015] The heavy metal content SI (mg·m -2 a -1 ) is calculated as SI=WC, where W represents the irrigation water volume of crops (L) and C represents the heavy metal concentration in the irrigation water of crops (mg / L).

[0016] ② Calculate the heavy metal content Q brought into the soil by atmospheric deposition based on the detected heavy metal concentration; atmospheric deposition includes two types of dry and wet deposition, such as atmospheric dust and precipitation, and the atmospheric deposition flux is the sum of atmospheric dry and wet deposition. The literature records that the measurement method of dry and wet deposition is to directly calculate through the recovered annual dust collection tank samples, or to calculate separately through the semi-annual dust collection tank and the seasonal dust collection tank. A large number of studies have shown that atmospheric deposition is one of the important input sources of heavy metals in the soil, expressed as Q.

[0017] ③ Calculate the heavy metal content FI brought into the soil by fertilization based on the detected heavy metal concentration; Fertilizer input: A large amount of fertilizer is input during agricultural production, and most of the fertilizers currently on the market contain a large amount of heavy metal elements, so fertilizer input is also one of the important input sources of heavy metals in the soil. According to the yearbook data, only nitrogen fertilizer, phosphate fertilizer, potassium fertilizer and organic fertilizer are considered when calculating the amount of heavy metals brought into the soil by fertilizer application. The heavy metal content in various fertilizers is based on the statistical analysis of a large amount of literature data to obtain its mean or average value.

[0018] The heavy metal content FI (mg·m -2 a -1 ) is calculated as FI = CF, where C represents the heavy metal concentration in the fertilizer (mg kg -1 ), F is the annual fertilizer usage (kg·m -2 ).

[0019] ④ Calculate the heavy metal content LMP brought into the soil by livestock and poultry manure based on the detected heavy metal concentration; Livestock and poultry manure: Most of the livestock and poultry manure is used to return to the fields. In the farmland system, livestock and poultry manure is also one of the sources of heavy metals in the soil. This article calculates the amount of heavy metals brought by livestock and poultry manure based on the yearbook data, and only considers the amount of heavy metals brought into the soil by five types of manure: pig manure, cattle manure, sheep manure, chicken manure and large livestock. Among them, the manure emissions of poultry such as broilers, laying hens, ducks, geese, etc. are estimated according to the manure emissions of chickens and their related parameter indicators. Here, large livestock refers to livestock that are larger in size and must be raised for more than 2 to 3 years to mature. The annual output of poultry is estimated according to the market chain.

[0020] The heavy metal content LMP (mg·m -2 a -1 ) is calculated as LMP =CRa / T, where C represents the concentration of heavy metals in livestock and poultry manure (mg·kg -1 ), R represents the excretion coefficient of livestock and poultry feces (kg·head -1 ·a -1 ), a represents the utilization rate of manure (%), T represents the planting area of ​​crops (m 2 ).

[0021] ⑤ Calculate the cumulative amount of heavy metals in the soil SC based on SI, Q, FI and LMP; According to the law of conservation of mass and material flow balance analysis, the cumulative amount of heavy metals in the soil is: SC=SI+Q+FI+LMP, where SI, Q, FI, and LMP represent the amount of heavy metals brought into the soil by water irrigation, atmospheric deposition, fertilizers, and livestock and poultry manure. SC represents the cumulative amount of heavy metals in the soil.

[0022] ⑥ Calculate the annual accumulation rate of heavy metals γ based on SC; according to different soil types, different soil bulk densities are given to each township, and the annual accumulation rate of heavy metals γ (mg kg -1 ·a -1 ) model estimation formula is γ = SC·ρ^-1·h^-1·π, where the accumulation of heavy metals in SC soil (mg·m -2 a -1 ), ρ represents soil bulk density (g·cm -3 ), h represents the soil layer thickness (cm), and π represents the unit conversion factor.

[0023] ⑦ Calculate the content of heavy metals in the soil contaminated by exogenous sources WY according to γ; the content of heavy metals in the soil contaminated by exogenous sources WY (mg·kg -1 ) is calculated as WY=γ+BD, where γ represents the annual accumulation rate of heavy metals (mg·kg -1 ·a -1 ), BD represents the initial heavy metal content in soil (mg kg -1 ).

[0024] Step 3: Alarm: Compare the calculated soil heavy metal content WY polluted by external sources with the limit value of the "Soil Environmental Quality Agricultural Land Soil Pollution Risk Control Standard". When WY exceeds the standard limit, an early warning signal is issued. The following combination Figure 1 , the contents of the present invention are described in detail through specific embodiments. Embodiment 1

[0025] Taking heavy metal mercury as an example, the pH value of the soil used to grow corn was tested to be greater than 7.5.

[0026] 1. Heavy metal concentration detection (1) Heavy metal concentration data in water bodies Detection method: Sampling water bodies, and using cold atomic absorption spectrophotometry to detect the concentration of mercury in the water.

[0027] Test results: The test results showed that the concentration of mercury in the water was 10 mg / L.

[0028] Calculation: The amount of crop irrigation water per square meter of soil per year is 1000 L. According to the formula "SI=WC", the content of heavy metals brought into the soil by irrigation each year is 10000 mg·m - ²·a - ¹.

[0029] (2) Data on heavy metal concentrations in the atmosphere Detection method: The LB-ZJ200 atmospheric heavy metal online analyzer was used to detect the total mercury concentration in the atmosphere to be 100 mg / m³, and the annual atmospheric deposition collected by the annual dust collection tank was 70 cm³.

[0030] Calculation: The amount of heavy metal mercury brought into the soil by atmospheric deposition each year is 0.0015 mg.

[0031] (3) Heavy metal concentration data caused by human factors Fertilizer: The annual fertilizer usage is 50 g / m², and the heavy metal mercury content in the fertilizer is 10 mg / kg. According to the formula "FI=CF", the heavy metal content brought into the soil by fertilizer is 0.5 mg·m - ²·a - ¹.

[0032] Livestock and poultry manure: The concentration of heavy metals in manure is 10 mg / kg. Livestock and poultry discharge 1600 kg / head·year per year. The utilization rate of manure is 75%, and the planting area of ​​crops is 250 m². According to the formula "LMP=CRa / T", the content of heavy metal mercury brought into the soil by livestock and poultry manure is 48 mg·m - ²·a - ¹.

[0033] 2. Heavy metal accumulation data Calculation: According to the formula "SC = SI + Q + FI + LMP", the cumulative amount of heavy metal mercury in the soil SC is 10000 mg·m - ²·a - ¹ + 0.0015 mg + 0.5 mg m - ²·a - ¹ + 48 mg·m - ²·a - ¹ = 10048.5 mg·m - ²·a - ¹.

[0034] Annual accumulation rate: soil bulk density is 1.2 g cm - ³, the soil layer thickness is 40 cm. According to the formula “γ=SC·ρ - ¹·h - According to the calculation of ¹”, the annual accumulation rate of heavy metal mercury is 16.75 mg kg - ¹·a - ¹.

[0035] The initial heavy metal mercury content in the soil was 0.5 mg / kg. According to the formula "WY=γ+BD", the heavy metal mercury content in the soil contaminated by external sources was 17.25 mg / kg.

[0036] 3. Alarm After comparing with the limit of 3.4 mg / kg in the "Soil Environmental Quality Agricultural Land Soil Pollution Risk Control Standard (Trial)" (GB15618-2018), it exceeds the control value and the screening value. External pollution, crop planting, and soil management should be stopped. Embodiment 2

[0037] Taking heavy metal mercury as an example, the pH value of the soil used to grow corn was tested to be greater than 7.5.

[0038] 1. Heavy metal concentration detection (1) Heavy metal concentration data in water bodies Detection method: Sampling water bodies, and using cold atomic absorption spectrophotometry to detect the concentration of mercury in the water.

[0039] Test results: The test results showed that the concentration of mercury in the water was 0.001 mg / L.

[0040] Calculation: The amount of irrigation water for crops per square meter of soil per year is 1000 L. According to the formula "SI=WC", the content of heavy metals brought into the soil by irrigation per year is 1 mg·m - ²·a - ¹.

[0041] (2) Data on heavy metal concentrations in the atmosphere Detection method: The LB-ZJ200 atmospheric heavy metal online analyzer was used to detect the total mercury concentration in the atmosphere to be 1 mg / m³, and the annual atmospheric deposition collected by the annual dust collection tank was 70 cm³.

[0042] Calculation: The amount of heavy metal mercury brought into the soil by atmospheric deposition each year is 0.000015 mg.

[0043] (3) Heavy metal concentration data caused by human factors Fertilizer: The annual fertilizer usage is 50 g / m², and the heavy metal mercury content in the fertilizer is 0.5 mg / kg. According to the formula "FI=CF", the heavy metal content brought into the soil by fertilizer is 0.025 mg·m - ²·a - ¹.

[0044] Livestock and poultry manure: The concentration of heavy metals in manure is 0.01 mg / kg. Livestock and poultry discharge 1600 kg / head·year per year. The utilization rate of manure is 75%, and the planting area of ​​crops is 250 m². According to the formula "LMP=CRa / T", the content of heavy metal mercury brought into the soil by livestock and poultry manure is 0.48 mg·m - ²·a - ¹.

[0045] 2. Heavy metal accumulation data Calculation: According to the formula “SC=SI+Q+FI+LMP”, the cumulative amount of heavy metal mercury in the soil SC is 1 mg·m - ²·a - ¹ + 0.000015 mg + 0.025 mg·m - ²·a - ¹ + 0.48 mg·m - ²·a - ¹ = 1.505 mg·m - ²·a - ¹.

[0046] Annual accumulation rate: soil bulk density is 1.2 g cm - ³, the soil layer thickness is 40 cm. According to the formula “γ=SC·ρ - ¹·h - ¹” calculation, the annual accumulation rate of heavy metal mercury is 0.0025 mg kg - ¹·a - ¹.

[0047] The initial heavy metal mercury content in the soil is calculated as 0.5 mg / kg. According to the formula "WY=γ+BD", the heavy metal mercury content in the soil contaminated by external sources is 0.5025 mg / kg.

[0048] 3. Alarm After comparison with the limit of 3.5 mg / kg in the "Soil Environmental Quality Agricultural Land Soil Pollution Risk Control Standard (Trial)" (GB15618-2018), it did not exceed the control value or the screening value, and monitoring can continue.

[0049] The present invention provides a soil heavy metal exogenous pollution early warning method based on material flow balance, including detection, heavy metal data calculation, alarm and other units. The present invention first performs real-time detection of heavy metal pollution caused by human factors such as water irrigation, atmospheric deposition, pesticide and fertilizer application, and then calculates and transmits the heavy metal increment and heavy metal accumulation brought into the soil by water irrigation, atmospheric deposition, pesticide and fertilizer application, and finally compares with the set standard threshold to achieve early warning of heavy metal exogenous pollution and prevent and control soil heavy metal pollution.

Claims

1. A soil heavy metal exogenous pollution early warning method based on material flow balance, comprising the following steps:

1. Testing: The heavy metal concentration in the crop irrigation water is detected by the heavy metal detection method in water; The concentration of heavy metals in the atmosphere is detected by the LB-ZJ200 atmospheric heavy metal online analyzer; Detect the concentration of heavy metals in fertilizers and livestock and poultry manure; 2. Data calculation: ① Calculate the heavy metal content SI brought into the soil by irrigation based on the detected heavy metal concentration; ② Calculate the heavy metal content Q brought into the soil by atmospheric deposition based on the detected heavy metal concentration; ③ Calculate the heavy metal content FI brought into the soil by fertilization based on the detected heavy metal concentration; ④ Calculate the heavy metal content LMP brought into the soil by livestock and poultry manure based on the detected heavy metal concentration; ⑤ Calculate the accumulation of heavy metals in soil SC based on SI, Q, FI and LMP; ⑥ Calculate the annual accumulation rate γ of heavy metals based on SC; the calculation formula of the annual accumulation rate γ of heavy metals is γ = SC·ρ^-1·h^-1·π, where SC is the accumulation of heavy metals in the soil, ρ represents the soil bulk density, h represents the soil layer thickness, and π represents the unit conversion coefficient; ⑦ Calculate the content of heavy metals in the soil contaminated by exogenous sources WY according to γ; the calculation formula of the content of heavy metals in the soil contaminated by exogenous sources WY is WY=γ+BD, where γ represents the annual accumulation rate of heavy metals, and BD represents the initial content of heavy metals in the soil; 3. Alarm: Compare the heavy metal content WY in the soil contaminated by external sources calculated in ⑦ with the limit value of the "Soil Environmental Quality Agricultural Land Soil Pollution Risk Control Standard". When WY exceeds the standard limit, an early warning signal will be issued.

2. The method for early warning of soil heavy metal exogenous pollution based on material flow balance according to claim 1 is characterized by: The calculation formula of the heavy metal content SI brought into the soil by irrigation is SI=WC, where W represents the irrigation water volume of crops, and C represents the heavy metal concentration in the irrigation water of crops.

3. The soil heavy metal exogenous pollution early warning method based on material flow balance according to claim 1 is characterized by: The calculation formula for the heavy metal content FI brought into the soil by fertilization is FI = CF, where C represents the heavy metal concentration in the fertilizer and F represents the annual fertilizer usage.

4. The method for early warning of soil heavy metal exogenous pollution based on material flow balance according to claim 1 is characterized by: The calculation formula for the heavy metal content LMP brought into the soil by livestock and poultry manure is LMP = CRa / T, where C represents the heavy metal concentration in livestock and poultry manure, R represents the excretion coefficient of livestock and poultry manure, a represents the utilization rate of manure, and T represents the planting area of ​​crops.

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