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Scientific Reports Volume 11, Article Number: 22542 (2021) Cite this article
Studying the form distribution and content of heavy metals in soil particles of different sizes is very important to prevent and control heavy metal pollution, but few studies regard heavy metal contaminated soil as a homogeneous body. In this study (Figure 1), goat manure, lime, and phosphate were used to stabilize exogenous lead (Pb). The different effects of these soil passivators on the total Pb and Pb in different chemical forms in soil particles of different sizes and the immobilization of Pb in the soil were studied. Through the laboratory passivation experiment for 45 days, the passivation effects of single and combined application treatments on exogenous Pb and distribution characteristics were analyzed and compared. Using fine sand microstructure and mineral composition analysis and characterization methods. The results showed that P5 alone and combined with LP5 had the best passivation efficiency. The content of DTPA-Pb decreased by 65.27% with P5, and the percentage of effective Pb in the soil particles of four sizes decreased significantly. After applying LP5 to the original soil, the contents of TCLP-Pb and effective Pb (weak acid leaching and reducible Pb) were significantly reduced by 71.60% and 25.12%, respectively. In addition, most of the total lead is concentrated in coarse sand and clay, while the content in fine sand and silt sand is low. The combined application of GL5 significantly increased the content of weak acid extractable and reducible Pb in fine sand, silt and clay. Through SEM and XRD analysis, it is found that the diffraction peaks of the P5 treatment group may be related to the formation of insoluble Pb containing compounds, which are mainly mineral components, including quartz, feldspar and mica. LP shows great potential. Research on the passivation of heavy metal lead contaminated soil in the natural environment. In summary, we should consider further research on the different dosage and metal pollution degree of passivation agent and different combination forms under natural conditions, and choose the appropriate passivation agent according to the soil texture. It is of great significance for the restoration of lead-contaminated soil.
Soil is the material basis and indispensable natural resource for human survival. With the rapid progress of industrialization and urbanization, the contradiction of heavy metal pollution of soil has become increasingly prominent. Lead (Pb), as a highly accumulated heavy metal element in the soil, has a wide range of sources and is very harmful to the ecology. The discharge of the "three wastes", the unreasonable application of pesticides and fertilizers, and mining and smelting activities will cause soil lead pollution. Among them, the mining and smelting processes of lead-zinc mines cause the most serious pollution.
Pb is unevenly distributed among soil particles of different sizes, and Pb is preferentially adsorbed on the surface of small soil particles2. Studies have shown that the finer the soil particles, the stronger the enrichment capacity of heavy metals3. At the same time, fine soil particles are more likely to migrate under the co-migration of colloids, leading to pollution of other environmental media4,5. In addition, the physical and chemical properties of the soil make the distribution of the chemical activity of lead extremely uneven, resulting in a large difference in the absorption efficiency of lead by organisms6. At present, there are many remediation techniques for heavy metal contaminated soil. Conventional soil remediation techniques include washing7, phytoremediation8, fixation9 and heat treatment10. The scope of application and repair effect of different methods are also different11. In-situ chemical passivation can better meet the remediation requirements of heavy metal contaminated soil in terms of remediation time and economic cost, and its passivation effect and mechanism have been extensively studied. Organic materials such as lime and phosphate are cheap and come from a wide range of sources, and have excellent passivation effects on heavy metals12. Organic materials reduce the effectiveness of heavy metals through adsorption, complexation/chelation, redox, etc., and indirectly reduce the harm of heavy metals by affecting the physical and chemical properties of the soil and the abundance and activity of soil microorganisms13,14. Lime promotes Pb2 concentration to form Pb(OH)2 and PbCO3 deposits by increasing soil pH15, thereby reducing the availability of heavy metals. Phosphate and lead can form phosphate precipitates and form very stable phosphorus-lead with halogens (Cl-, F-) in the soil. The passivation mechanism of lime and phosphate is relatively simple16. However, the soil is not homogeneous, and the distribution of different material components in soil particles of different sizes is not uniform. Many specific reactions or phenomena only occur within specific soil particle size ranges17. Therefore, the conversion and enrichment of heavy metals in soils with different particle sizes is very important for the remediation effect of passivators. Although there are many studies on the chemical passivation remediation of lead-contaminated soil, most of them regard the soil as a homogeneous body. There are few studies on the migration and transformation of Pb in soils with different particle sizes after adding passivators to the soil. The internal microscopic mechanism of the passivators to repair Pb contaminated soil is still unclear. The content of the three forms (DTPA-Pb, TCLP-Pb and continuously extracted fractions) is used to reflect the stabilizing effect of different passivators on lead-contaminated soil. By calculating the total Pb and Pb forms in soil particles of different sizes, and discussing the distribution of Pb in contaminated soil, it has a certain reference value for the improvement of heavy metal contaminated soil.
Therefore, the purpose of this study is to: (1) compare the effects of different passivators on the stability of exogenous Pb contaminated soil; (2) analyze the effects of different passivators on the enrichment and form distribution of Pb in soils with different particle sizes; 3) Use characterization methods to analyze and discuss the micromorphology of different soil particles; (4) Evaluate the best types of potential soil passivators for lead fixation in exogenous lead contaminated soils (Figure 1).
An overview of the main contents of the study.
The test samples were taken from vegetable fields in Huaxi District, Guiyang City, Guizhou Province, China (106°39′48″ east longitude, 26°21′20″ north latitude), and the soil type was yellow soil. Choose topsoil (0-20-cm), and its physical and chemical properties are shown in Table 1. The tested moist soil samples were air-dried at room temperature in the laboratory and then passed through a 2-mm mesh sieve. The Pb(NO3)2 solution was used as the source of Pb pollution. After adding it to the tested soil, the concentration of Pb2 in the tested soil reached 2000 (mg kg−1). Using the weighing method, ultrapure water is added to keep the moisture content of the soil sample at 60%. After culturing for 45 days, air dry, and grind the soil through a 2 mm mesh sieve before use.
Goat manure (GM), lime (Ca(OH)2) and phosphate (Ca(H2PO4)·2H2O) are the three passivators used in the study. Goat manure (GM) was collected from a goat farm in Xiuwen City, Guizhou Province, and its physical and chemical properties are shown in Table 2. Ca(OH)2 (L) and Ca(H2PO4)·2H2O (P) were purchased from Upright and China Zhiyuan Chemical Reagent Co., Ltd. Reagents are guaranteed.
Passivation experiments are divided into single application and combined application, with a total of 13 treatment groups. Each treatment group was repeated 3 times, followed by addition as a control check (CK). Single application: the application rates of GM, L, and P are 1%, 2% and 5%, respectively. Combined application: mix GM, L and P in a ratio of 1:1, and the application quality is equal to 5% of the soil quality (GL5, GP5, LP5 and GLP5) (Table 3). Put 300 g of lead-contaminated soil into a 500 mL experimental pot. Mix the soil with the passivation agent in the above proportion. The soil moisture content is maintained at 60%. After 45 days of cultivation, the soil is dried and ground for later use.
The research method refers to 18, and the separation process of soil with different particle sizes is shown in Figure 2. The sample is passed through a 2mm mesh sieve, first processed by ultrasonic, and then the coarse sand (0.2-2mm) is separated by ultrasonic. Wet sieve method. Finally, according to the Stokes formula, the fine sand particles (0.02-0.2 mm), silt particles (0.002-0.02 mm) and clay particles (< 0.002 mm) are separated sequentially by centrifugation. In order to ensure accurate separation of particle size, the size distribution of soil particles was verified by a laser particle size analyzer (Mastersizer2000, Malvern, UK) immediately after separation. Soils of different particle sizes are dried at 50°C and passed through a 0.149mm mesh sieve for later use.
Separation process of different particle size soils (Microsoft Office Visio).
The time required for centrifugation can be obtained by the Stokes formula:
Where n is the viscosity of the soil suspension at the experimental temperature, and R (cm) is the distance between the precipitation and the centrifugal axis. S (cm) is the distance between the suspension surface and the centrifugal axis during centrifugation, N (r min−1) is the centrifugal speed, D (μm) is the diameter of the soil particles, △s is the suspended soil particles and the surrounding liquid due to the difference in gravitational acceleration . Since the part <2-μm was not classified in this study, it was set to 1.653.
Refer to 19 for soil pH, organic matter, cation exchange capacity, total nitrogen, total phosphorus and available phosphorus. A glass electrode pH meter (model PHS-3C, Shanghai Instrument and Electric Co., Ltd.) was used to determine the pH value of the soil sample in a water-soil suspension (2.5:1), and the SOM content was determined by the K2Cr2O7 volumetric method. CEC is determined by the hexaamine cobalt trichloride extraction-spectrophotometric method. The total N and P and the quickly available P are measured by an automatic discontinuous chemical analyzer (CleverChem200, DeChem-Tech Gmbh Co., Ltd, Germany). Measure the total Pb and K content by HCl, HNO3, HF, HClO4 digestion. Available lead (DTPA-Pb) is analyzed by DTPA (diethylene triamine pentaacetic acid) extraction method (China GB/T 23739-2009). TCLP-Pb is analyzed by CH3COOH2O. The improved BCR21 continuous extraction method was used to determine the chemical form of Pb in the soil. The content of Pb and K was analyzed with an atomic absorption spectrometer (GGX-800, Beijing Haiguang Instrument Co., Ltd.).
The statistical analysis of the original data in the study uses Microsoft Excel 2019 to organize and calculate. The experimental data provided in this article is the average of three samples. The standard deviation of the mean is represented by error bars. Pearson correlation matrix analysis is processed by SPSS 22.0 software. The experimental images are drawn by Origin 2019 and Microsoft PowerPoint.
For farmland soils, the absorption of heavy metals by crops is directly related to the quality of agricultural products. The choice of evaluation methods is more inclined to evaluate the impartability of plants. DTPA can usually extract the sum of water-soluble forms, exchange forms, and organic binding forms of heavy metals, including The content of some oxides and secondary clay minerals of heavy metals, because they are the closest to plant growth, and plant availability best represents heavy metals22. DTPA-Pb is considered to be one of the bioavailable or unstable pools with high potential ecotoxicity to the environment. It has been shown that Pb in plants is significantly related to the extractable part of DTPA in soil24. The passivation effect increased with the increase of the amount of passivation agent in the single application treatment group. 45 days after administration of GM5, L5 and P5, the DTPA-Pb concentration significantly decreased by 123.86 (mg kg-1), 321.41 (mg kg-1) and 508.93 (mg kg-1), respectively (Figure 3a). Among all treatment groups, P5 had the better passivation effect on DTPA-Pb content (a decrease of 65.27%), while GM1 had the weakest passivation effect on DTPA-Pb content (a decrease of 6.61%). By comparing and analyzing the difference in stability of Pb(OH)2 and Pb3(PO4)2, it is found that the passivation effect of phosphate is better than that of alkaline materials25. In some cases, it is reported that the passivation effect of L on heavy metals is better than the passivation effect of organic materials on acid soil, which is similar to this study26. However, this is closely related to the physical and chemical properties of the soil and the amount of application. The Toxic Characteristic Leaching Procedure (TCLP) was created after US EPA Method 1311 (USEPA 1992) with minor modifications27. Detecting the dissolution and migration of heavy metals in solid media or waste is one of the most commonly used ecological risk assessment methods. As shown in Figure 3b, the content of TCLP-Pb in the treatment group was significantly different. The application of transgene can reduce the content of TCLP-Pb in the tested soil, and the reduction amount is inversely proportional to the application amount. However, the application of L significantly increased the content of TCLP-Pb, and the content of TCLP-Pb decreased with the increase in the amount of L. Among all treatment groups, LP5 was the most effective among all treatment groups, and the content of TCLP-Pb was significantly reduced by 71%. GL5 has the least effect, increasing the TCLP-Pb content by 59%. Overall, the P5, GP5 and LP5 treatment groups had the best effects on DTPA-Pb and TCLP-Pb. However, in this study, the application of L significantly increased the content of TCLP-Pb. Due to the decrease in pH, lower levels of lime treatment (1%, 2% and 5%) will increase the content of TCLP-Pb in the soil and the leaching of Pb. Lime induces the formation of CSH and ettringite. The decrease of TCLP-Pb may be due to the complexing of Pb on the surface of the formed calcite. A high pH value will enhance the adsorption of Pb on the surface of calcite. Immobilization may also be related to the formation of calcium silicate hydrate, calcium aluminum hydrate, and ettringite through adsorption, phase mixing, or addition of lime instead. Generally speaking, the effectiveness of quicklime treatment is closely related to the physical and chemical properties of the soil. One-way analysis of variance was used to analyze the significant differences in DTPA-Pb content under different passivation agents. In the single application group, the extraction capacity of DTPA-Pb varies with the dosage, and this phenomenon is most obvious in the phosphate treatment. The content of DTPA-Pb in the P5 treatment was significantly lower than that in the other treatment groups, which was similar to the content of TCLP-Pb under the treatment of different passivators. However, it is worth noting that the passivation effect of TCLP-Pb in the combined application group is the most significant, which is different from the extraction form of DTPA-Pb.
The content of DTPA-Pb and TCLP-Pb under different passivators (Origin 2019b). (CK: control check, GM: goat dung, L: Ca(OH)2, P: Ca(H2PO4)·2H2O, GL: goat dung Ca(OH)2, GP: goat dung Ca(H2PO4)·2H2O, LP ：Ca(OH)2 Ca(H2PO4)·2H2O, GLP: goat manure Ca(OH)2 Ca(H2PO4)·2H2O; 1, 2, 5 represent the ratio of passivating agent).
The sequential extraction of heavy metals in the soil is carried out in accordance with the revised European Community Reference Sequence Extraction Program Bureau. The chemical forms of heavy metals in the soil pose varying degrees of threats to the ecological environment. Passivators can reduce the harm of heavy metals to organisms and the ecological environment by changing the existence of heavy metals. Therefore, the morphological classification scheme can be used to evaluate the passivation effect of lead-contaminated soil. The content percentage of Pb chemical form can directly reflect the influence of passivating agent on the distribution of Pb form in Pb-contaminated soil (Figure 4). In the original soil, Pb mainly exists in weak acid extractable, reducible and oxidizable forms, and the sum of the three forms is about 73.56%. The results of the study showed that both the LP5 and P5 treatment groups significantly reduced the percentage of weakly acid extractable and reducible Pb in the Pb-contaminated soil, which were reduced by 21.54% and 25.12% respectively compared with the CK treatment group (without soil passivator). The GM group and L group reduced the effective Pb content, and the reduction was positively correlated with the amount of passivator. The application of L in the tested soil increased the pH of the soil and helped increase the content of weakly acid extractable Pb, because L increased the concentration of Pb(OH)2 and Pb2CO3. All treatment groups can reduce the content of reducible Pb in the tested soil. The single treatment effects brought by GM2, L5 and P5 are ranked in descending order. In the treatment group, oxidizable lead and GM, L and P were reduced by 1.17-5.44%, 4.22-14.19% and 2.35-17.89%, respectively. Both the GM and P treatment groups increased the residual Pb content, and P5 had the best passivation effect. Pb fixation may be attributed to the P-induced conversion of Pb from soluble copper alumina to insoluble Pb phosphate minerals30,31. However, the L treatment group had little effect on the residual Pb content. GL5 increased the weak acid leaching Pb content by 10.45%. The results showed that the mixed passivation effect of sheep dung and lime was poor, which increased the active Pb content in the test soil. However, GP5, LP5 and GLP5 reduced the weak acid leaching Pb content in the passivator treatment group, indicating that phosphate has a significant effect in the combined application treatment. DTPA extractant is composed of (diethylenetriaminepentaacetic acid (DTPA), triethanolamine (TEA) and CaCl2·2H2O), and is used to extract Pb from the soil. Its content has a high correlation with the absorption of Pb by crops. Acetic acid is used as an extractant for TCLP-Pb, and the TCLP-Pb test is designed to determine the mobility of Pb contaminants in the soil32. Pb is continuously extracted with acetic acid, hydrogen amine hydrochloride, hydrogen peroxide and ammonium acetate as extractants. Pb can be classified into 4 different extraction forms according to the effectiveness. reduce. The three extraction methods are quite different, mainly due to the different types of extractants used, and different experimental conditions have significant differences in the extracted Pb content.
The influence of different passivating agents on the morphology of Pb (Origin 2019b). (CK: control check, GM: goat dung, L: Ca(OH)2, P: Ca(H2PO4)·2H2O, GL: goat dung Ca(OH)2, GP: goat dung Ca(H2PO4)·2H2O, LP ：Ca(OH)2 Ca(H2PO4)·2H2O, GLP: goat manure Ca(OH)2 Ca(H2PO4)·2H2O; 1, 2, 5 represent the ratio of passivating agent).
The distribution of total lead content under different types of passivators and application doses is shown in Figure 5. The total lead content showed a bimodal distribution in soils of different particle sizes. Specifically, coarse sand and clay have a higher total lead content, while fine sand and silt sand have a lower total lead content. The reasons for Pb enrichment in coarse sand are complicated. Some researches believe that SOM and other substances aggregate on the surface of coarse sand particles under the compound action of Pb33. However, it is believed that coarse sand contains coarse minerals or heavy minerals and has a strong ability to intercept heavy metals. The larger the specific surface area of the clay particles, the higher the content of clay minerals and Fe-Mn/Fe-Al oxides, and the greater the adsorption capacity for total Pb. The total Pb content in coarse sand, fine sand and clay in the transgenic treatment group increased to varying degrees, and the effect of GM2 was the most significant. The total lead content in coarse sand and clay increased by 583 (mg kg-1) and 317 (mg kg-1) respectively, which may be due to the higher lead content in GM. GM5 can increase the total Pb content in fine sand. Through GM passivation, the Pb level in clay decreases, which may be due to the increase in SOM content after GM application. However, SOMs of different particle sizes have different effects on sand, silt and clay in the event, and they are arranged in descending order. In general, higher SOM content can improve the adsorption capacity of pollutants, and the negative charge on the surface of soil particles increases with the increase of the amount of L, forming a cementing material of CaCO3 and Ca(OH)2. The large specific surface area of the clay particles brings a large amount of negative charge and strong adsorption capacity for Pb2. The cementitious material in the coarse sand particles exchanges and adsorbs Pb2 to increase Pb retention. Compared with CK, the enrichment of Pb in coarse sand and fine sand increased after P treatment, but the Pb content in silt and clay particles had no significant effect. The combined application of GL5, GP5, LP5 and GLP5 reduced the content of Pb in coarse and fine sands, but had little effect on the content of Pb in silt. The total Pb content in clay particles increased to 110.93 (mg kg−1), which may be It is caused by the interaction of different passivators during the fixation process.
The total lead content in the soil of different particle sizes under the action of passivators (Origin 2019b).
The redistribution of Pb in soils with different particle sizes is affected by passivators, which may also change the distribution form of Pb in soils with different particle sizes, thereby affecting the effectiveness of Pb in the soil. It can be seen from Figure 6 that there is no significant difference in the distribution of Pb in all soil particle sizes under CK treatment, indicating that there is no significant difference in the distribution trend of exogenous Pb in all soil particle sizes after entering the soil36. It is worth mentioning that P5 treatments with other particle sizes have a better stabilizing effect on exogenous Pb-contaminated soil, and the percentage of weakly acid extractable and reducible high bioavailability Pb is significantly reduced. The reason may be that the smooth coating formed by soluble phosphate and other mineral crystals made Pb2 trapped on the surface of soil particles37. In general, in the combined treatment group, the percentage of oxidizable and residual Pb decreased significantly, while the percentage of extractable and reducible Pb with a high utilization rate of weak acid increased, and the passivation effect was not strong.
The influence of passivators on the lead content in soils of different particle sizes (Origin 2019b). (CK: control check, GM: goat dung, L: Ca(OH)2, P: Ca(H2PO4)·2H2O, GL: goat dung Ca(OH)2, GP: goat dung Ca(H2PO4)·2H2O, LP ：Ca(OH)2 Ca(H2PO4)·2H2O, GLP: goat manure Ca(OH)2 Ca(H2PO4)·2H2O; 1, 2, 5 represent the ratio of passivating agent).
Observe the morphology and microstructure of soil samples by SEM (SU8020, Hitachi, Japan). SEM was used to scan and photograph the fine sand surface before and after the passivation treatment, and the magnification was 5000 times. It can be seen from Figure 7 that the micromorphology changes of soil particles after passivation treatment are as follows: GM increases the number of large particles above 10 mm on the surface of fine sand, and after L treatment, the surface smoothness increases, but the surface small particles are significantly reduced. Phosphorus treatment results in a prominent structure on the surface of soil particles. In the combined application of GP5, the surface of soil particles was smooth, and the fine particles were greatly reduced, but the large particles larger than 10-mm increased significantly. After applying LP5, deep wrinkles, grooves and protrusions appeared on the surface of soil particles, and large particles over 15mm appeared on the surface. The surface fine particles are reduced and the surface structure is relatively flat, but the surface sags after applying GLP5.
SEM images of fine sand particles before and after passivation treatment. (CK: control check, GM: goat dung, L: Ca(OH)2, P: Ca(H2PO4)·2H2O, GL: goat dung Ca(OH)2, GP: goat dung Ca(H2PO4)·2H2O, LP ：Ca(OH)2 Ca(H2PO4)·2H2O, GLP: goat manure Ca(OH)2 Ca(H2PO4)·2H2O; 1, 2, 5 represent the ratio of passivating agent).
The crystal structure of the soil sample was characterized by an X-ray diffractometer (Brook D8 Advance, Brook GmbH, Germany). The simulated lead-contaminated soil particles mainly contain minerals such as quartz, feldspar, mica, zeolite, illite, chlorite, and calcite (Figure 8). The quartz content in coarse sand, fine sand and silt sand is high, accompanied by feldspar, mica, and calcite. The content of zeolite and illite is low. The main components of clay particles are illite and chlorite 38,39. As the soil particle size decreases, clay minerals gradually increase. The characteristic peaks of feldspar in coarse sand showed differences (around 30°) among several passivating agent treatment groups. In the GLP5 treatment, the peak appeared at d = 0.319 nm (2θ = 27.89°). The reason may be that Pb-Ca mixed with phosphate and Pb3(PO4)231. In several treatments, another diffraction peak appeared at d = 0.324 nm (2θ = 27.43°), which may be caused by the presence of PbSO3 in the coarse sand particles. All the passivation treatment groups containing L in the fine sand showed obvious diffraction peaks, indicating that the application of L can induce the formation of PbSi2O7 in the fine sand. In addition, under the treatments of L5 and GL5, the diffraction peaks of Pb3O2Cl2 appeared at d = 0.209 nm (2θ = 43.15°) and d = 0.187 nm (2θ = 48.49°), and PbF2 appeared at d = 0.191 nm (2θ = 47.15°). The additional peak at d = 0.303 nm (2θ = 29.40°) for L5 treatment also appeared in silt and clay, indicating that L can also induce the formation of Pb3Si2O7. The characteristic peaks of feldspar appear in GM, L, GL5 and GLP5, because GM and L contain calcium minerals under application. The reason for the lack of characteristic peaks in the P treatment group may be that part of L and GM contains calcium and chemical reactions occur. The diffraction peaks of the P treatment group are different from the other treatment groups, with more glitch peaks, and the spikes are also different from other treatment groups. Sandy soil is usually composed of large-grained soil with high quartz content and primary minerals such as feldspar, mica, and zeolite, which will be broken into fine particles under the action of weathering. Coarse sand, fine sand and silt sand contain more crystalline minerals, and the XRD patterns are more similar. The peaks are regular. As the size of soil particles decreases, there are fewer and fewer broken crystal minerals. In the XRD amorphous feature map, there are many burr peaks, and the X-ray diffraction intensity of clay is obviously weaker than that of fine sand and silt sand, indicating that the clay component has a higher degree of dispersion and less crystal form.
XRD patterns of coarse sand, fine sand, silt sand and clay particles after passivation treatment. (1: quart, 2: feldspar, 3: mica, 4: zeolite, 5: illite, 6: chlorite, 7: calcite) (Origin 2019b). (CK: control check, GM: goat dung, L: Ca(OH)2, P: Ca(H2PO4)·2H2O, GL: goat dung Ca(OH)2, GP: goat dung Ca(H2PO4)·2H2O, LP ：Ca(OH)2 Ca(H2PO4)·2H2O, GLP: goat manure Ca(OH)2 Ca(H2PO4)·2H2O; 1, 2, 5 represent the ratio of passivating agent).
P5 treatment can reduce the content of DTPA-Pb in lead-contaminated soil by 65.27%, and treatment with LP5 can reduce the content of TCLP-Pb and effective Pb by 71.60% and 25.12%, respectively. The two passivation treatment groups performed well in this study. The total Pb is mainly concentrated in coarse sand and clay, and its content is lower in fine sand and silt sand. P5 can significantly reduce the percentage of effective Pb (weak acid extractable and reducible Pb) of different particle sizes, while the combined treatment group can increase the content of weak acid extractable and reducible Pb, which may be the interaction between passivators Caused. Increased the availability of Pb. Through SEM and XRD analysis, it is found that the diffraction peaks of the P5 treatment group may be related to the formation of insoluble lead-containing compounds, and the main mineral components are quartz, feldspar and mica. Future research should focus on the amount of passivation agent, the degree of heavy metal pollution, and consider the appropriate combination of passivation agents under natural conditions.
The data set used and/or analyzed in the current research can be obtained from the corresponding author upon reasonable request.
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Thanks to the National Natural Science Foundation of China (41807336), Guizhou Science and Technology Support Program ([2017]2580), and Guizhou Science and Technology Program ([2019]1213) for financial support.
School of Geography and Environmental Science, Guizhou Normal University, Guiyang 550025
Zhao Shuai, Cai Xiongfei, Wang Ji, Ding Li, Zhao Shijie, Yu Xinjie, Xu Die, Zhang Shuai
The Incubation Base of the State Key Laboratory of Karst Mountain Ecological Environment of Guizhou Province, Guiyang, 550025
Zhao Shuai, Cai Xiongfei, Wang Ji, Ding Li, Zhao Shijie, Yu Xinjie, Xu Die, Zhang Shuai
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Methodology: SZ, DL; Software: SZ, XY, DX; Modified manuscript: XC, JW, SZ The first draft of the manuscript was written by Zhao Shuai. The final manuscript read and approved by all authors.
The author declares no competing interests.
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Zhao, S., Cai, X., Wang, J., etc. The stabilizing effects of three passivators on soil contaminated by exogenous lead with different particle sizes[J]. Scientific Reports 11, 22542 (2021). https://doi.org/10.1038/s41598-021-01685-6
DOI: https://doi.org/10.1038/s41598-021-01685-6
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