Health risk assessment of trace metal(loid)s in agricultural soils based on Monte Carlo simulation coupled with positive matrix factorization model in Chongqing, southwest China

This study aimed to investigate the pollution characteristics, source apportionment, and health risks associated with trace metal(loid)s(TMs) in the major agricultural producing areas in Chongqing, China. We analyzed the source apportionment and assessed the health risk of TMs in agricultural soils by using positive matrix factorization(PMF) model and health risk assessment(HRA) model based on Monte Carlo simulation. Meanwhile, we combined PMF and HRA models to explore the health risks of TMs in agricultural soils by different pollution sources to determine the priority control factors. Results showed that the average contents of cadmium(Cd), arsenic (As), lead(Pb), chromium(Cr), copper(Cu), nickel(Ni), and zinc(Zn) in the soil were found to be 0.26, 5.93, 27.14, 61.32, 23.81, 32.45, and 78.65 mg/kg, respectively. Spatial analysis and source apportionment analysis revealed that urban and industrial sources, agricultural sources, and natural sources accounted for 33.0%, 27.7%, and 39.3% of TM accumulation in the soil, respectively. In the HRA model based on Monte Carlo simulation, noncarcinogenic risks were deemed negligible(hazard index <1), the carcinogenic risks were at acceptable level(10^(-6)<total carcinogenic risk ≤ 10^(-4)), with higher risks observed for children compared to adults. The relationship between TMs, their sources, and health risks indicated that urban and industrial sources were primarily associated with As, contributing to 75.1% of carcinogenic risks and 55.7% of non-carcinogenic risks, making them the primary control factors. Meanwhile, agricultural sources were primarily linked to Cd and Pb, contributing to 13.1% of carcinogenic risks and 21.8% of non-carcinogenic risks, designating them as secondary control factors.

Contamination and human health risk assessment of heavy metal(loid)s in topsoil and groundwater around mining and dressing factories in Chifeng,North China

Chifeng is a concentrated mining area for non-ferrous metal minerals,as well as a key prevention and control area for heavyduty enterprises.This situation necessitates an efective ecological and human health risk assessment of heavy metal(loid)s driven by the wide distribution of metal ore processing,mining,and smelting factories in Hexigten Banner and Bairin Left Banner.We conducted surveys to assess the levels of heavy metal(loid)s(Cr,As,Pb,Cd,and Hg)in the topsoil and groundwater of the areas.The results indicated that the concentrations of As,Cd,and Pb in partial soil samples exceeded the environmental quality standards of Grade II.Based on contamination assessments,such as geoaccumulation indices and pollution indices,we inferred that Cd,Pb,and As were primary pollutants in topsoil.Potential ecological risks when considered as part of the average risk indices(RI)are up to 1626.40 and 2818.76,respectively,in the two areas.Comparative analysis revealed that Cd posed a very high potential ecological risk,followed by As.Moreover,the evaluation showed that the three exposure pathways of carcinogenic and non-carcinogenic risk followed a descending order:inhalation>ingestion>dermal contact,except for Pb.Arsenic in topsoil posed a potential non-carcinogenic risk to human health,while there were no adverse efects of As in groundwater.In addition,the average total carcinogenic risk for As in the two areas,as well as the risk of Pb in the topsoil of Bairin Left Banner and all the fve heavy metal(loid)s in groundwater,exceeded human tolerance.Pb–Zn mines caused higher human health risks.In addition,the tandem contamination of heavy metal(loid)s in soil and groundwater was not obvious.This research study provides a basis for pollution remediation to control heavy industry-induced ecological and health risks of heavy metal(loid)s.

Multiple assessments, source determination, and health risk apportionment of heavy metal(loid)s in the groundwater of the Shule River Basin in northwestern China

Global ecosystems and public health have been greatly impacted by the accumulation of heavy metal(loid)s in water.Source-specific risk apportionment is needed to prevent and manage potential groundwater contamination with heavy metal(loid)s.The heavy metal(loid)s contamination status,water quality,ecological risk,and health risk apportionment of the Shule River Basin groundwater are poorly understood.Therefore,field sampling was performed to explore the water quality and risk of heavy metal(loid)s in the groundwater of the Shule River Basin in northwestern China.A total of 96 samples were collected from the study area to acquire data for water quality and heavy metal(loid)s risk.There was noticeable accumulation of ferrum in the groundwater of the Shule River Basin.The levels of pollution were considered to be moderately low,as evaluated by the degree of contamination,heavy metal evaluation index,heavy metal pollution index,and Nemerow pollution index.The ecological risks were also low.However,an assessment of the water quality index revealed that only 58.34%of the groundwater samples had good water quality.The absolute principal component scores-multiple linear regression model was more suited for this study area than the positive matrix factorization model.There were no obvious noncarcinogenic or carcinogenic concerns for all types of receptors according to the values of the total hazard index and total carcinogenic risk.The human activities and the initial geological environment factor(65.85%)was the major source of noncarcinogenic risk(residential children:87.56%;residential adults:87.52%;recreational children:86.77%;and recreational adults:85.42%),while the industrial activity factor(16.36%)was the major source of carcinogenic risk(residential receptors:87.96%;and recreational receptors:68.73%).These findings provide fundamental and crucial information for reducing the health issues caused by heavy metal(loid)s contamination of groundwater in arid areas.

Distribution, Mobility, and Health Risks Assessment of Trace Metals in River Sediments from Intense Agricultural Activity Areas in West Africa

The economy of West African countries is mainly based on agriculture. However, the trace metal(loid)s contamination status in rivers is relatively unknown in the region. In this work, 45 surface sediments collected from the Bandama, Comoé, and Bia Rivers in south and south eastern Côte d’Ivoire (West Africa), were analyzed for total metal concentrations and chemical speciation. The results showed that the river sediments were considerably contaminated by Cd and moderately contaminated by As, Cu, Pb, and Zn. Significant spatial variations were observed among the stations but not between the rivers. Metals Cd and Cu were likely to cause more ecological risks. The speciation analysis unravelled that the metal(loid)s partitioned mainly in the residual fraction, with the potential mobile fraction varying from 14% to 28%. The study calls for establishment of strict policies relative to the application of fertilizers and agrochemicals and mining activities to protect the environment and human health risks.

Assessment of the Level of Metal(loid)s Pollution and Bioactive Compounds Screening of Anthill Soil

The anthill soil is used by hypertensive elderly and teenagers from Oshikoto region (Namibia) and many of them testified stabilization of their blood pressure to normal after consuming the anthill soil-derived aqueous extracts. This study therefore investigated and/or assessed the physicochemical parameters, the contents of some metal(loid)s (and their associated potential health risks) and the qualitative composition of bioactive compounds of this anthill soil. The homogenous soil sample collected from various anthill soils in the Oshikoto region was used to obtain the measurements of physiochemical parameters. The elemental contents were determined (using an Inductively Coupled Plasma Optical Emission Spectrophotometer) after acid digestion in accordance with the EPA method 350B and their potential health risk assessments were performed. Methanol, aqueous methanol, and aqueous-based extracts were generated via maceration extraction process prior to the screening of bioactive compounds using standard diagnostic assays. The oxidation reduction potential (164.4 ± 16.6 mV) was the only physicochemical parameter whose value was within the World Health Organization limits for drinking water whereas, total dissolved solids (23 ± 5.5 mg/L), electrical conductivity (44 ± 10.1 uS/cm) and pH (5.35 ± 0.33) were out of specifications. Phenolic compounds, flavonoids, terpenoids, and cardiac glycosides were present in anthill soil (with respect to the extractants used) to which its antihypertensive properties can be attributed in addition to some of the studied mineral components. With respect to the pH, TDS and EC, and the contents of most metal(loid)s in relation to their health risk assessment values, the results suggest that aqueous extracts derived from this anthill soil can be deemed unsuitable for human consumption.

Spatiotemporal simulation and predication of heavy metal(loid) concentrations in coal chemical industrial areas with a soil environmental capacity model

Heavy metal (loid)(HM) accumulation in the soil and the HM spatiotemporal distribution have important implication for soil pollution prevention and remediation. The present study investigated the concentrations and spatiotemporal distributions of lead (Pb), mercury (Hg), cadmium (Cd), chromium (Cr) and arsenic (As) in the topsoil of a coal chemical plant in Ningxia Aulonomous region (Ningxia), China. Topsoil samples (/?= 153) were obtained using the checkerboard method, and the HM concentrations were determined. The soil residual rates of the five HMs were measured with leaching experinients and were applied in a soil environmental capacity model to predict the quarHitiHive variation of the HM concentrations. The predicted results were employed to estimate the HM spatiotemporal distribution within 2() years with the Kriging technique. The number of sampling sites, where all five HM concentratio ns exceed their corresponding background values in Ningxia, would be increased from 0 to 90% within 1() years of the plant operation. In addition, Pb and Cd were distributed along the traffic routes. Mercury and As were distributed near fuel gas emission vents. Chromium was mainly accumulated in slag dumps. The study may provide the theoretical and practical foun d at ion for future HM pollution control in coal chemical plants.

Microbial Remediation of Heavy Metal(loid)Contaminated Soil: A Review

Because of the rapid development of industrial processes, increased urban pollution and agricultural chemicals applied in recent years, heavy metal(loid) pollution in soil has been very serious, and there is an urgent need for fast and efficient removal of heavy metal(loid) pollution. Currently, environmental microorganisms are always used to perform biological alteration or improvement of soils and sewage. Using functional microorganisms that are resistant to toxic heavy metal(loid) ions for alteration and transformation of heavy metal(loid)s in ionic form is an effective measure for microbial remediation of heavy metal(loid)contaminated soil. This paper reviewed the microbial remediation mechanism of heavy metal(loid) contaminated soils, and the approaches for breeding bacteria those can be used for highly efficient removal of heavy metal(loid)s, as well as the application examples of microbial remediation and transformation of heavy metal(loid) contaminated soil, and finally described the future trends and further research work of heavy metal(loid) contaminated soils by microbial remediation.

Migration and distribution characteristics of soil heavy metal(loid)s at a lead smelting site

Heavy metal(loid)s contamination is a constant issue at smelting sites.It is essential to investigate the spatial distribution and migration characteristics of heavy metal(loid)s in the soil for environmental management and remediation strategies of non-ferrous smelting sites.In this study,203 soil samples from 57 sites were collected in a typical lead smelting site.The findings demonstrated that there were significant Pb,Zn,Cd,and As contamination in soil samples.The spatial distribution of heavy metal(loid)s showed strong spatial heterogeneity,the contaminated soil areas of Pb,As,Cd,and Zn were 99.5%,98.9%,85.3%,and 72.4%,respectively.Pb,Cd,and As contamination of the soil reached a depth of 5 m,which migrated from the surface to deep soil layers.The leaching contents of Zn,Pb,and As decreased obviously in 3-4 m soil layer,but the leaching content of Cd was still high,which indicated the high migration of Cd.With the increase of depth,the proportion of acid soluble fraction of heavy metal(loid)s decreased,and the residual fraction increased.The acid soluble fraction of Cd accounted for a higher proportion,and As mainly existed in reducible and residual fractions in soil.According to the calculation of the migration factor,the migration of heavy metal(loid)s in soils were ordered as Cd>Zn>Pb>As.The outcomes are advantageous for risk reduction and site remediation for non-ferrous metal smelting sites.

Na_(2)S改性生物炭高效吸附重金属离子:制备及吸附机理

以废弃芦苇为原料、硫化钠(Na_(2)S)为改性剂,制备了对Pb^(2+)、Cd^(2+)、Zn^(2+)具有高效吸附性能的Na_(2)S改性生物炭(BCS)。通过扫描电镜-能谱(SEM-EDS)、红外光谱(FTIR)、元素分析等手段对改性前后的生物炭进行了表征。结果显示,Na_(2)S改性能够为生物炭引入多种含硫官能团,提升孔体积并增加比表面积。Langmuir模型拟合结果表明,随着改性剂Na_(2)S溶液浓度的增加,BCS对重金属离子的吸附能力得到提升。在pH为2.0~6.0的范围内,BCS对重金属离子的吸附能力随pH增加逐步增强。在pH=6.0时,BCS对Pb^(2+)、Cd^(2+)、Zn^(2+)的最大吸附量分别为494.99、131.14、94.89 mg/g。根据动力学实验结果可知,BCS对重金属离子的吸附行为符合伪二级动力学模型。吸附机理主要包括表面官能团的络合、离子交换和静电吸附。本研究可为废弃物的再利用以及废水中的重金属的高效去除提供一种环境友好且可行的解决方案。

Accumulation and Cycle of Heavy Metals in Sonneratia apetala and S. caseolaris Mangrove Community at Futian of Shenzhen, China

This paper reports the absorption, accumulation, distribution and cycle of Cu, Pb, Zn, Cr and Ni in S. apetala + S. caseolaris, mangrove community at Futian Mangrove Nature Reserve of Shenzhen. The Cu, Pb, Zn, Cr and Ni contents in forest soil increase from bottom to surface layers, and the storage of the five heavy metals in the surface layer (depth 0 ~ 30 cm) is Zn > Pb > Ni > Cr > Cu. The concentration ability is S. caseolaris > S. apetala > K. candel. The existing accumulation of Cu, Pb, Zn, Cr and Ni in the community μis 23 019.63g/m2μ, 23 429.66g/m2μ, 117 870.42g/m2μ, 6 835.80g/m2μ, and 12 995.22g/m2μ, respectively. The annual absorption is 6 592.57g/m2μ, 2 664.80g/m2μ, 23 123.56g/m2μ, 853.24g/m2μ, and 1 990.95g/m2, respectively. The annual return is μ3 179.50g/m2μ, 1 300.65g/m2μ, 7 401.31g/m2μ, 398.99g/m2μ, and 646.20g/m2, respectively. The annual net retention accumulation of Cu, Pb, Zn, Cr and Ni in the community is 3 413.07μg/m2, 1 364.15μ g/m2, 15 722.25μg/m2, 454.25μg/m2, and μ1 344.75g/m2, respectively. The turn over periods of Cu, Pb, Zn, Cr and Ni are 8,19,15,18 and 21 years, respectively.

Heavy metal removal from aqueous solution using carbonaceous K_2S-impregnated adsorbent

A novel carbonaceous adsorbent for heavy metal removal was prepared from raw coal by one-step simple sulfur impregnation using K2S. Raw coal was mixed with K2S powder and then heated at 800℃ for 30 min in nitrogen to produce K2S char. The sulfur content and form in K2S char were determined, and the ability of K2S char to adsorb Zn^2＋, Cd^2＋ and Pb^2＋ was examined. The K2S impregnation was effective at impregnating sulfur into coal, especially in the form of elemental, thiophenic and sulfatic sulfur. The sulfur content of K2S char was higher than those of raw coal and pyrolysis char. The Zn^2＋ removal in 2.4 mmol/L of Zn^2＋ solution by K2S char was higher than raw coal with the removal rate of 100%. K2S char adsorbed Pb^2＋ and Cd^2＋ in 24 mmol/L of Pb^2＋ and Cd^2＋ solution with the removal rate of 97% and 35%, respectively. The elution extents of adsorbed Pb^2＋ and Cd^2＋ were zero in distilled water and 27% in 0.1 mol/L HCl solution. These results indicated that an effective adsorbent for heavy metal ions was prepared from coal using K2S sulfur impregnation, and that the adsorbed metals were strongly retained in K2S char.

Effect of cyclic drying and wetting on engineering properties of heavy metal contaminated soils solidified/stabilized with fly ash

Solidification/stabilization （S/S） is one of the most effective methods of dealing with heavy metal contaminated soils. The effects of cyclic wetting and drying on solidified/stabilized contaminated soils were investigated. A series of test program, unconfined compressive strength （UCS） test, TCLP leaching test and scanning electron microscopy （SEM） test, were performed on lead and zinc contaminated soils solidified/stabilized by fly ash. Test results show that UCS and the leaching characteristics of heavy metal ions of S/S contaminated soils are significantly improved with the increase of fly ash content. UCS of S/S soils firstly increases with the increase of the times of drying and wetting cycles, after reaching the peak, it decreases with it. When the pollutant content is lower （1 000 mg/kg）, the TCLP concentration first slightly decreases under cyclic drying and wetting, then increases, but the change is minor. The TCLP concentration is higher under a high pollutant content of 5 000 mg/kg, and increases with the increase of the times of drying and wetting cycles. The results of scanning electron microscopy （SEM） test are consistent with UCS tests and TCLP leaching tests, which reveals the micro-mechanism of the variations of engineering properties of stabilized contaminated soils after drying and wetting cycles.

Pollution characteristics and source apportionment of heavy metal(loid)s in soil and groundwater of a retired industrial park

Heavy metal(loid)s(HMs)pollution has become a common and complex problem in industrial parks due to rapid industrialization and urbanization.Here,soil and groundwater were sampled from a retired industrial park to investigate the pollution characteristics of HMs.Results show that Ni,Pb,Cr,Zn,Cd,and Cu were the typical HMs in the soil.Source analysis with the positive matrix factorization model indicates that HMs in the topsoil stemmed from industrial activities,traffic emission,and natural source,and the groundwater HMs originated from industrial activities,groundwater-soil interaction,groundwater-rock interaction,and atmosphere deposition.The sequential extraction of soil HMs reveals that As and Hg were mainly distributed in the residue fraction,while Ni,Pb,Cr,Zn,Cd,and Cu mainly existed in the mobile fraction.Most HMs either in the total concentration or in the bioavailable fraction preferred to retain in soil as indicated by their high soil-water partitioning coefficients(K_(d)),and the K_(d) values were correlated with soil pH,groundwater redox potential,and dissolved oxygen.The relative stable soil-groundwater circumstance and the low active fraction contents limited the vertical migration of soil HMs and their release to groundwater.These findings increase our knowledge about HMs pollution characteristics of traditional industrial parks and provide a protocol for HMs pollution scrutinizing in large zones.

Responses of acrocarpous moss communities to heavy metal(Fe,Mn,Cd)and sulfur pollution in the Changgou carbonate manganese ore,SW China

Bryophyte communities have been widely used to monitor and assess heavy metal pollution in soil,air and water.However,the unique value of acrocarpous moss in monitoring environmental pollution and the harm of non-metallic sulfur to human health caused by carbonate manganese mining were seldom considered in previous studies.This study investigated the heavy metal and sulfur pollution level by soil and moss sample collection in Changgou manganese ore and its surrounding environment in the Zunyi area,Guizhou Province,China.By means of cluster analysis,diversity analysis,correlation analysis and redundancy analysis,the relationship between dominant moss communities and major pollutants were analyzed.The results showed that there were pollutants such as iron(Fe),manganese(Mn),cadmium(Cd),sulfur(S)and others in the 500 meters buffer zone centered on Changgou manganese ore.The ore sorting area and waste rock accumulation area were considered as the most seriously polluted,followed by the ore outlet area and ore transport line,at last the miners’living area and vegetable planting area were the least polluted.A total of 23 species of moss communities were identified in the Changgou manganese ore area,among which 9 were dominant,including Bryum blindii Bruch&Schimp.(Bry.bli),Weissia planifolia Dix(Wei.pla)-Bry.bli,Bryum caespiticium Hedw.(Bry.cae),Bryum pallescens Schleicher ex Schw?gr.(Bry.pal),Didymodon longicostatus X.J.Li et Iwats(Did.lon),Weissia brachycarpa(Nees&Hornsch.)Jur.(Wei.bra),Trichostomum brachydontium Bruch.(Tri.bra),Bryum argenteum Hedw.(Bry.arg)Wei.bra and Bryum algovicum Sendt.ex M?ll.Hal.(Bry.alg),all of which are from the acrocarp species.Bry.cae showed a strong tolerance to S,Did.lon to Fe,Bry.pal to Cd and Bry.bli to Mn.There was a significant correlation between the main polluting elements and the dominant bryophyte community(P<0.05),indicating a high biological indicator value.Together,our results can provide the scientific basis for soil pollution monitoring and human health risk assessment in carbonate manganese mining areas.

Heat shock proteins development in different stages of schistocerca gregaria as response to heavy metals intoxication

The induction of heat shock proteins in different stages of S. gergaria exposed to long and short term contamination with heavy metals, Cd and Pb in food was determined, revealing a prominent variable effect in response to the term of exposure and the type of contamination. HSP 70 was specially quantified and characterized to reveal the probability of using HSP as a biomarker for pollution.

重金属汞胁迫下菲律宾蛤仔GPx和GST基因表达分析

为研究重金属汞胁迫下菲律宾蛤仔谷胱甘肽过氧化物酶(glutathione peroxidase,GPx)和谷胱甘肽-S-转移酶(glutathione-S-transferase,GST)基因的表达情况,用汞对指示生物菲律宾蛤仔(Ruditapes philippinarum)进行单一慢性暴露试验,分别在0、12、24 h以及2、3、4、5、6、7和8 d时检测菲律宾蛤仔内脏团和鳃中GPx和GST基因的表达情况。结果表明,菲律宾蛤仔内脏团中GPx和GST基因的表达量都呈现波动变化趋势,分别在24和12 h时表达量最高(P<0.05),6 d时GPx基因表达量最低(P>0.05),3 d时GST基因表达量最低(P<0.05);GPx基因在鳃中的表达量在8 d时最高(P<0.05);鳃中GST基因的表达量在5 d时最高(P<0.05)。以上结果表明汞暴露在短期内能够诱导GPx和GST基因进行不同程度的表达,但其随着时间的延长呈明显的抑制作用。该研究结果为揭示重金属汞对菲律宾蛤仔的毒性机理提供了理论依据。

Pollution characteristics and quantitative source apportionment of heavy metals within a zinc smelting site by GIS-based PMF and APCS-MLR models

The abandoned smelters present a substantial pollution threat to the nearby soil and groundwater.In this study,63 surface soil samples were collected from a zinc smelter to quantitatively describe the pollution characteristics,ecological risks,and source apportionment of heavy metal(loid)s(HMs).The results revealed that the average contents of Zn,Cd,Pb,As,and Hg were 0.4,12.2,3.3,5.3,and 12.7 times higher than the risk screening values of the construction sites,respectively.Notably,the smelter was accumulated heavily with Cd and Hg,and the contribution of Cd(0.38)and Hg(0.53)to ecological risk was 91.58%.ZZ3 and ZZ7 were the most polluted workshops,accounting for 25.7%and 35.0%of the pollution load and ecological risk,respectively.The influence of soil parent materials on pollution was minor compared to various workshops within the smelter.Combined with PMF,APCS-MLR and GIS analysis,four sources of HMs were identified:P1(25.5%)and A3(18.4%)were atmospheric deposition from the electric defogging workshop and surface runoff from the smelter;P2(32.7%)and A2(20.9%)were surface runoff of As-Pb foul acid;P3(14.5%)and A4(49.8%)were atmospheric deposition from the leach slag drying workshop;P4(27.3%)and A1(10.8%)were the smelting process of zinc products.This paper described the distribution characteristics and specific sources of HMs in different process workshops,providing a new perspective for the precise remediation of the smelter by determining the priority control factors.

Heavy metal(loid)s in fruit-growing soils of tropical Hainan Island in China:Pollution,ecological-health risks,spatial assessment,and source analyses

Hainan Island is the most important tropical fruit production area in China.In this study,372 soil samples and corresponding fruit and irrigation water samples were collected from Hainan orchards and analysed to determine the concentrations of six heavy metal(loid)s:Cd,Hg,As,Pb,Cr,and Cu.The pollution status,potential risks,possible sources,and spatial distribution patterns of soil heavy metal(loid)s were comprehensively investigated.The fruit and irrigation water samples had negligible amounts of heavy metal(loid)s,and the potential human health risk for fruit consumers was at a safe level.The heavy metal(loid)concentrations in most soil samples were lower than the national risk screening values.However,significant local accumulation of heavy metal(loid)s,especially Cd,Cr,and Cu,relative to their background values was observed.Moreover,the combined effects of the heavy metal(loid)s only led to a mild pollution level and low ecological risk throughout the study area.Noncarcinogenic risks were not observed among the local residents,and carcinogenic risks were within an acceptable range.The acidic soil in the study area increased the risk of soil Cd pollution,and organic matter affected the distribution of the tested metal(loid)s in the soil.Uncommon geogenic sources with high background values were the sources of Cr and Cu,anthropogenic activities primarily led to Cd,Pb,and As contamination,and a combination of anthropogenic and natural sources was responsible for Hg emissions.The research suggested that appropriate strategies must be implemented to track and reduce soil heavy metal contaminants in the northern and western region of the Hainan orchard area.The results can provide valuable information for policies on pollution prevention and management,the environment,and human health protection in the study region.

竹笋重金属污染与膳食风险评估及有效阻控研究

重金属污染是全球公认的环境问题,重金属胁迫下农产品安全成为近些年的研究热点。竹笋作为一种健康食品,在世界范围内广受欢迎。此前,已经发表了许多关于竹笋重金属污染方面的论文,重金属污染已对竹笋安全构成威胁。该文主要综述了竹笋的重金属污染特征、膳食健康风险及阻控方法。结果表明,竹笋主要受Pb污染,毛竹冬笋重金属超标比其他竹笋严重,笋皮和笋根中富集系数较大,基于总量通过非致癌目标风险系数(target hazard quotient,THQ)评价重金属的健康风险,表明儿童的健康风险会比成人的高,但基于此评价尚存在不足,需进行下一步的生物可给性和建立细胞模型等进行健康风险的综合评估。在控制竹笋重金属污染上,可考虑土壤的理化性质,Ca肥、富Se肥或纳米材料可在未来加以应用,以期为竹笋安全生产提供参考。

不同重金属离子对C-S-H凝胶影响及其固化稳定性

通过溶液法人工合成不同钙硅比C-S-H凝胶,借助XRD,SEM,XPS,TEM,ICP等测试方法,分析研究了C-S-H凝胶对不同种类、不同含量重金属离子(Cr3+,Cr6+,Pb2+,Zn2+,Cd2+等)的俘获能力及其稳定性.结果表明:钙硅比不同,C-S-H凝胶对重金属离子固化稳定性及其固化机制均存在一定差异,高钙硅比C-S-H凝胶对重金属离子固化稳定性较强;重金属离子种类及价态不同,其在C-S-H凝胶中的结合方式及固化能力也不同,其中C-S-H凝胶对Cu2+,Cd2+,Zn2+等离子的固化能力较强,对Cr6+的固化能力较弱.水化液相中,C-S-H凝胶对Cr3+,Pb2+,Zn2+等多种重金属离子的固化能力低于其对单一重金属离子的固化能力;水化液相中Cr6+的存在,会对C-S-H凝胶对Pb2+的固化及其稳定性产生巨大影响,而Cr3+的存在对其影响则较小.