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CN-121977904-A - Method for detecting concentration of organic heavy metal in soil

CN121977904ACN 121977904 ACN121977904 ACN 121977904ACN-121977904-A

Abstract

The invention belongs to the technical field of organic heavy metal detection, and discloses a method for detecting the concentration of organic heavy metal in soil, which comprises the following steps of weighing soil, adding a weak acid extractant, oscillating, centrifuging, taking supernatant, filtering, adjusting the pH of filtrate to be neutral, and diluting; compared with the traditional physicochemical analysis method, the method has the advantages that the sensitivity is improved by 1-2 orders of magnitude, the early warning requirement of micro pollution in the soil environment can be met, the method has high specific recognition capability on target organic heavy metals, the interference of other ions in the soil matrix is effectively shielded through a specific resuscitation buffer solution formula, the authenticity of detection signals is ensured, the operation is simple and convenient, the time consumption is short, expensive large-scale equipment is not needed, the potential of on-site rapid detection is realized, and the method is suitable for screening of mass soil samples.

Inventors

  • HUANG ZENG
  • LIU JIE
  • HUANG HONGMING
  • TANG YAN
  • CHEN YANG
  • HUANG BODANG
  • Qin Huafang
  • JI TONG
  • Tang Yangzheng

Assignees

  • 广西壮族自治区生态环境监测中心

Dates

Publication Date
20260505
Application Date
20260211

Claims (10)

  1. 1. The method for detecting the concentration of the organic heavy metal in the soil is characterized by comprising the following steps of: (1) Weighing soil, adding an extractant, oscillating, centrifuging, taking supernatant, filtering, adjusting the pH of filtrate to be neutral, and diluting; (2) Adding a resuscitating buffer solution, malic acid or tartaric acid, MOPSO, tween20, his-His dipeptide, low-concentration EDTA, glycine betaine, spermidine, GSH/GSSG and Trolox, preparing a resuscitating buffer solution containing soluble components, adding the resuscitating buffer solution into micropores of preset freeze-drying engineering bacteria, and standing for 5-10 minutes to enable cells to be primarily resuscitated; (3) Placing a filter disc on the inner bottom of the micropore, adding Amberlite XAD-4 or XAD-7 micro resin particle suspension pre-wetted by the extracting solution into the micropore to ensure that the final concentration is 0.5-2mg/mL, respectively adding a liquid to be detected and a negative/positive control solution into the corresponding hole, incubating in a dark place under a constant temperature condition, and generating an optical signal when the reporter gene is expressed; (4) Measuring signal values of all holes by using a microplate luminescence/fluorescence detector, substituting the signal values of the samples into a standard curve equation after normalization treatment, calculating the concentration of the extracting solution, and then converting to obtain the mass ratio concentration of the target in the soil according to the volume of the extracting solution, the dilution factor and the mass of the soil sample.
  2. 2. The method for detecting the concentration of the organic heavy metal in the soil according to claim 1, wherein in the step (2), 100mL of recovery buffer solution containing the soluble component is prepared by the following steps of adding malic acid into 90ML recovery solution, adding MOPSO into the recovery buffer solution to dissolve the recovery buffer solution, adjusting pH to 6.8-7.2 by using NaOH or KOH after dissolving the recovery buffer solution, adding Tween20 into the recovery buffer solution, shaking the recovery buffer solution uniformly to obtain mixed solution, adding His-His dipeptide into the mixed solution to dissolve the recovery buffer solution, adding low-concentration EDTA into the mixed solution, adding glycine betaine, spermidine and GSH/GSSG into the mixed solution, and adding Trolox into the mixed solution to obtain the recovery buffer solution containing the soluble component in the step S22.
  3. 3. The method for detecting the concentration of organic heavy metals in soil according to claim 2, wherein in the step S21, 0.1-0.5mL of 1M malic acid is added to the 90ML resuscitation fluid, and the final concentration is 1-5mM.
  4. 4. The method for detecting the concentration of organic heavy metals in soil according to claim 2, wherein in step S21, the MOPSO concentration is 50-100mM.
  5. 5. The method for detecting the concentration of organic heavy metals in soil according to claim 2, wherein in the step S21, tween20 is selected to have a concentration of 0.005% -0.02%, and a pipette is selected to add 5-20. Mu.L of Tween20.
  6. 6. The method for detecting the concentration of organic heavy metals in soil according to claim 2, wherein in the step S22, EDTA mother liquor concentration is 0.02M, the dosage is 50-300 mu L, the final concentration is 0.01-0.06mM, and glycine betaine concentration is 1-5mM.
  7. 7. The method for detecting the concentration of the organic heavy metal in the soil according to claim 2, wherein in the step S22, the spermidine concentration is 0.5-2mL of 10mM mother liquor, the GSH/GSSG ratio is 5:1, and the mixture is added after the GSH/GSSG ratio is weighed.
  8. 8. The method for detecting the concentration of organic heavy metals in soil according to claim 2, wherein the concentration of Trolox is 0.1-0.3mM and the amount is 1-3ml in step S23.
  9. 9. The method for detecting the concentration of the organic heavy metal in the soil according to claim 1, wherein in the step (3), the filter disc is constructed by the following method, namely, in the step S31, the porous polyethylene/hydrophilic PTFE filter disc with the pore diameter of 5-10 mu m is cut into the shape of the bottom of a microporous plate hole, and in the step S32, the filter disc which is cut by the upper book is placed at the bottom of the microporous plate; and adding the Amberlite XAD-4 micro resin particle suspension pre-wetted by the extracting solution into the micropores, naturally settling the resin on the filter disc to form a thin bed, and purifying the liquid to be detected and the negative/positive control liquid through the resin layer and the bottom filter disc.
  10. 10. The method for detecting the concentration of the organic heavy metal in the soil according to claim 1, wherein in the step (4), the standard solution concentration is obtained by taking the logarithm (log (C)) and carrying out linear regression analysis on the log (C)) and the corresponding normalized signal value (R), so as to obtain a standard curve equation: Wherein R is a normalized luminescence/fluorescence signal value, C std is the concentration of a standard solution, k is the slope of a standard curve, and b is the intercept of the standard curve; The formula for calculating the concentration of the extracting solution is as follows: Wherein, C ext is the concentration of organic heavy metal in the soil extract to be detected, rsample is the signal value after the normalization of the sample hole to be detected; the soil mass ratio concentration conversion formula is as follows: Wherein, C soil is the mass ratio concentration of organic heavy metals in soil, V ext is the total volume of extractant used for extracting soil samples, D is dilution times, m soil is the dry weight of the weighed soil samples, and F is unit conversion coefficient.

Description

Method for detecting concentration of organic heavy metal in soil Technical Field The invention belongs to the technical field of organic heavy metal detection, and particularly relates to a method for detecting the concentration of organic heavy metal in soil. Background Soil is used as a core component of an ecological system, and is a basic guarantee for crop growth, grain safety and human living environment quality. With the acceleration of industrialization process, unreasonable application of chemical fertilizers and pesticides in agricultural production, solid waste stacking, atmospheric sedimentation and other human activities, the problem of soil heavy metal pollution is increasingly prominent, wherein organic heavy metals become important attention objects in the current soil pollution prevention and control field due to unique environmental behaviors and ecological risks. The organic heavy metal is a compound formed by complexing, chelating or covalently bonding heavy metal ions with organic matters such as humic acid, fulvic acid, amino acid and the like in soil, and common types include organic mercury (such as methyl mercury and ethyl mercury), organic arsenic (such as arsenobetaine, arsenocholine), organic lead (such as tetraethyl lead) and the like. Compared with inorganic heavy metals, the organic heavy metals have stronger fat solubility and biological mobility, are easier to enrich in organisms through food chains, form serious threat to plant, microorganism, soil animal and human health, for example, the toxicity of methyl mercury is more than 100 times of that of inorganic mercury, can be absorbed into the food chains through crops to cause diseases such as nervous system injury, endocrine disturbance and the like, have strong mobility in soil, are easy to pollute underground water, have obvious destructive effect on soil microbial community structures, and lead to the reduction of soil fertility. At present, soil environment management provides higher requirements for organic heavy metal detection, so that not only is the chemical morphology of heavy metal accurately identified, but also the ultra-trace detection of micro-pollution level (ppt level) is realized, and technical support is provided for early warning and risk management and control of soil pollution. However, the existing detection technology still has a plurality of limitations, and is difficult to meet the actual application requirements: In the traditional physicochemical analysis method, an inductively coupled plasma mass spectrometry (ICP-MS) and an Atomic Absorption Spectrometry (AAS) are common technologies for detecting the total amount of heavy metals, but the methods cannot distinguish the chemical forms of the heavy metals, can only measure the total content of the heavy metals in soil, and cannot accurately reflect the actual ecological risks of the organic heavy metals. In order to realize morphological distinction, a High Performance Liquid Chromatography (HPLC) and ICP-MS combined technology is widely applied, but the method has the remarkable defects that the pretreatment flow of a sample is complex, organic and inorganic components are required to be separated through multi-step operations such as ultrasonic extraction, solid phase extraction and the like, the time is as long as hours or even days, the instrument equipment is expensive (the price of a single ICP-MS is usually millions of yuan), the maintenance cost is high, the professional skill requirements of operators are strict, the on-site rapid detection cannot be realized, the detection process is easily interfered by chloride ions, sulfate ions, metal cations and the like in a soil matrix, the detection signal drift is caused, the detection sensitivity of ultra-trace organic heavy metals is insufficient, the ultra-trace heavy metals can only reach ppb level, and the early warning requirement of micro-pollution is difficult to meet. The biosensor detection method has the advantages of simple operation and strong specificity as an emerging technology, but the prior art still faces the bottleneck that the traditional biosensor adopts microorganism strains which have poor stability in complex soil matrixes, heavy metal ions, organic matter decomposition products and the like in the soil are easy to inhibit microorganism activity, so that detection signals are weakened or distorted, a resuscitation buffer solution has a single formula, can only meet basic metabolism requirements of microorganisms, cannot effectively shield matrix interference, and also cannot maintain the specific recognition capability of the microorganisms on target objects, and suspension particles, macromolecular organic matters and the like in soil extract are adhered to the surfaces of the sensors to influence signal transmission, so that quantitative accuracy is reduced. In addition, the partial biosensor detection method can only realize qualitative or semi-quantitative analysi