评估土壤微量元素生物有效性测定方法

Trace element-contaminated soils (TECSs) are one of the consequences of the past industrial development worldwide.Excessive exposure to trace elements (TEs) represents a permanent threat to ecosystems and humans worldwide owing to the capacity of metal(loid)s to cross the cell membranes of living organisms and of human epithelia,and their interference with cell metabolism.Quantification of TE bioavailability in soils is complicated due to the polyphasic and reactive nature of soil constituents.To unravel critical factors controlling soil TE bioavailability and to quantify the ecological toxicity of TECSs,TEs are pivotal for evaluating excessive exposure or deficiencies and controlling the ecological risks.While current knowledge on TE bioavailability and related cumulative consequences is growing,the lack of an integrated use of this concept still hinders its utilization for a more holistic view of ecosystem vulnerability and risks for human health.Bioavailability is not generally included in models for decision making in the appraisal of TECS remediation options.In this review we describe the methods for determining the TE bioavailability and technological developments,gaps in current knowledge,and research needed to better understand how TE bioavailability can be controlled by sustainable TECS management altering key chemical properties,which would allow policy decisions for environmental protection and risk management.     

Arsenic in Rice Soils and Potential Agronomic Mitigation Strategies to Reduce Arsenic Bioavailability: A Review

Soils used for rice (Oryza sativa L.) cultivation in some areas contain high concentrations of arsenic (As) due to irrigation with groundwater containing As and intensive use of agrochemicals or industrial residues containing As. To restrict rice uptake of As in these soils, approaches to reduce As input and bioavailability must be considered. One approach to reduce As input into rice soils or uptake by rice is cultivating rice under aerobic, intermittent flooding, or alternate wetting and drying (AWD) conditions, rather than in submerged soils, or use of irrigation water low in As. For reducing As bioavailability in soil, aerobic or AWD rice culture and application of biochar, sulfur (S), and/or rice polish to soil are promising. Moreover, use of As-hyperaccumulating plant species (e.g., Pteris vittata L.) in rotation or combinations with favourable plant species (e.g., Azolla, Chlorella, or Nannochloropsis species) can also be promoted, in addition to using rice cultivars that are tolerant to As. Though applications of high doses of phosphorus (P), iron (Fe), and silicon (Si) fertilizers have shown promise in many instances, these methods have to be practiced carefully, because negative effects have also been reported, although such incidents are rare. Major factors affecting As speciation and bioavailability in soil are chemical properties such as redox status, pH, and Fe, P, Si, and S concentrations, physical properties such as texture and organic matter, and biological properties such as methylation activity by soil microorganisms. However, as many of these factors interact, long-term examination under field conditions is needed before measures are recommended for and implemented in farmers' fields.     

不同改良剂施用对污染土壤养分转化及砷和铅生物有效性的影响

为比较不同小龙虾壳基土壤改良剂对砷、铅复合污染土壤的修复效果,通过盆栽试验,探究施用1％(w/w)小龙虾壳粉(CSP)、甲壳素(CT)、小龙虾壳炭(CSB)及甲壳素-小龙虾壳炭配施(CT-CSB,CT∶CSB为1∶1)对土壤养分、酶活性、重金属生物有效性及青菜生长的影响.结果 表明,不同改良剂施用均可显著提高土壤pH和...     

利用化学和生物指标评价不同来源土壤铜的生物有效性

Bioavailability is a key parameter in assessing contaminant transfer to biota. However, the input patterns and soil use types may impact the metal bioavailability. Several soil parameters were measured including chemical properties, such as pH, organic C, and Cu solution/solid speciation, and biological properties, such as soil microbial biomass C （SMBC）, seed germination, and root elongation, to evaluate the bioavailability of Cu contaminated soils from three different sources, i.e., non-ferrous metal mining, Cu-based fungicides, and Cu-smelting. The results revealed that free Cu2＋ ion in soil solution and the ratios of Cu fractions to total Cu content in the solid phase could not be used to predict total Cu content in soils. The indexes of seed germination and root elongation appeared not to be good biomonitors of Cu contamination in soils, which were more sensitive to soil pH and soil organic carbon （SOC）. Relationships between SMBC and soil Cu forms or the ratio of SMBC/SOC and soil Cu forms showed that free Cu2＋ ion and humie acid-complexed Cu could significantly inhibit soil microbial activities. Our findings suggested that both metal chemical forms and biological bioassays should be considered as a complementary technique rather than an alternative to evaluate the metal bioavailability from different pollution sources.     

In situ stabilization of arsenic in soil with organoclay, organozeolite, birnessite, goethite and lanthanum-doped magnetic biochar

Arsenic (As) is a known carcinogen and naturally occurring semi-metal in soils and in the Earth''s crust. Contamination of soils and water with As poses a serious threat to millions of people worldwide due to its health hazards and toxicological properties. Hence, devising novel and efficient methods for remediation of contaminated areas has attracted a great deal of interest across the globe. In this study, we investigated the usefulness of synthetic birnessite, goethite, hexadecylpyridinium chloride-modified montmorillonite (HDPC-M), hexadecylpyridinium bromide-modified zeolite (HDPB-Z), and lanthanum (La)-doped magnetic biochar produced from eucalyptus bark (La-Euchar) as adsorbents at 10% dosage for As stabilization in a soil spiked with 1 000 mg kg^-1 As. The effectiveness of the above adsorbents in As immobilization in soil was assessed using single-step extractions with 2 mol L^-1 HNO₃ and deionized water, the simplified bioaccessibility extraction test (SBET) method, and sequential extraction with the modified Community Bureau of Reference (BCR) method. Application of the adsorbents shifted the exchangeable fraction of As to more recalcitrant fractions and dramatically reduced the exchangeable fraction by 6%-99% and the extractable amounts with HNO₃, deionized water, and SBET method by 30%-92%, 17%-95%, and 12%-90%, respectively, compared to the unamended control. The immobilizing effects of adsorbents on As decreased in the sequence of birnessite > La-Euchar > goethite > HDPB-Z > HDPC-M. Birnessite exhibited great affinity for As and drastically reduced As extractability by more than 90% in all single extractions. The results revealed that HDPC-M, HDPB-Z, La-Euchar, birnessite, and goethite are promising immobilizing agents for in situ stabilization of As in terrestrial environments.     

亚洲土壤和地下水金属污染风险评价---综述近期研究趋势以及现有环境法律法规

Asia is experiencing a more rapid economic growth compared to any other regions. The contamination of soil and groundwater with metals can mainly be attributed to human activities; therefore, risk assessments to characterize the nature and magnitude of risks to humans and ecological receptors from contaminants are important. Risk assessments are often iterative processes, which involve identification and filling data gap. Experimental samplings, geostatistical and multivariate statistical methods as well as multimedia risk assessment modeling are the three major methodologies used in the assessment of metal contamination in soil and groundwater. This review highlights a number of measurements for improving risk calculation methods and expounds scientific approaches that involve the identification of the major source of contamination, exposure pathways and bioavailability of metals. In general, risk assessments of metals in soil and groundwater worldwide are mainly focused on the levels of contamination, identification of exposure pathways, and prediction of the probability of contamination. To date, very limited studies have reported the development of relevant environmental laws and policies in the regulation of soil and groundwater contamination in Asia. The development, variations and limitations in the regulations of soil and groundwater contamination among developed countries may provide helpful guidance for the developing countries in Asia.     

镉污染土壤中吐纳麝香的生物有效性及其评价

采用室内盆栽实验,以小麦为供试植物,研究重金属镉（Cd）和吐纳麝香（AHTN）复合污染对小麦植株生物量的影响以及Cd对土壤中AHTN生物有效性的影响,并应用聚2,6-二苯基对苯醚（Tenax-TA）、固相微萃取纤维（SPME）和三油酸甘油酯-醋酸纤维素复合膜（TECAMs）对土壤中的AHTN进行提取,以评价Cd污染土壤中AHTN对小麦的生物有效性。结果表明：AHTN-Cd复合污染土壤中的小麦植株生物量低于单一AHTN污染土壤;当AHTN浓度为5 mg·kg-1时,共存重金属Cd抑制AHTN在小麦地上和地下部的累积,其抑制作用随Cd浓度的增大而增强,抑制率最高达39.1%,AHTN在小麦体内从地下到地上的迁移随着Cd浓度的增加受到抑制,且浓度越高抑制作用越强,抑制率可达到19.0%;当AHTN浓度为10 mg·kg-1时,共存重金属Cd则促进AHTN在植物体内的累积,其促进率高达38.4%,AHTN从地下到地上的迁移受到诱导,促进率高达68.5%;在AHTN和Cd单一及复合污染土壤中,Tenax 24 h、SPME 12 h和TECAMs 12 h单点提取AHTN的量与小麦根部AHTN富集量显著相关,表明Tenax 24 h、SPME 12 h以及TECAMs 12 h对土壤中AHTN的提取量可以用来评价其生物有效性。     

农药污染土壤的生物强化修复技术研究进展

生物强化作为一种新型、高效的生物修复技术在污染环境治理中具有独特优势。针对目前土壤农药污染现状,本文介绍了土壤微生物修复方法中的生物强化技术的概念及内涵,探讨了在污染土壤环境中影响生物强化修复效率的生物及非生物因素,重点阐述了生物强化技术在4大类农药(有机氯类、有机磷类、拟除虫菊酯类杀虫剂和三嗪类除草剂)污染土壤修复中的研究进展及应用实例,并提出生物强化技术面临的问题和未来研究方向。     

Arsenic in field‐collected soil solutions and extracts of contaminated soils and its implication to soil standards

Large concentrations of arsenic in soils, sediments, and freshwaters require risk assessment across the Central Alps and other regions. We measured arsenic concentrations in soil samples collected from 38 sites located in the Austrian Central Alps that had been contaminated due to mining and smelter activities and geogenic mineralization. Medians and ranges of arsenic concentrations (in mg kg^—1) in the soil solid phase were: 77.1 (1—3000) for the total (As_t), 19.2 (0—726) for (NH₄)₂C₂O₄‐extractable (As_o), 2.35 (0—169) for (NH₄)₂HPO₄‐extractable (As_p), and 0.143 (0—11.1) for (NH₄)₂SO₄‐extractable (As_s) arsenic. Arsenic concentrations in soil solutions (As_sol) collected from organic surface layers and mineral horizons at five selected sites using suction cups fitted with nylon membranes ranged from 0 to 171 μg l^—1. Typically, the prevailing species of As in the soil solution was As(V). As_sol was correlated with As_s (As_sol = 0.279 + 15.6 As_s; r² = 0.938; n = 17) and As_t (As_sol = 1.272 + 0.043 As_t; r² = 0.833; n = 17). Using these empirical models, As_sol can be predicted quite accurately based on extraction with 0.05 M (NH₄)₂SO₄ or total arsenic concentrations in the soil. Linking these models to drinking water standards (DWS) we propose soil standards for freshwater protection that vary for As_s (mg kg^—1) between 0.62 (for DWS = 10 μg l^—1 WHO) and 3.19 (for DWS = 50 μg l^—1). Corresponding standards for As_t (mg kg^—1) are 203 (DWS = 10 μg l^—1) and 1133 (DWS = 50 μg l^—1). These considerations demonstrate that changes in legislation on DWS may have dramatic impact on As concentrations in soil that are acceptable for groundwater protection.     

菜地土壤铅、镉有效态与生物有效性研究

通过野外采样、室内测试分析,探讨重庆市北碚区菜地土壤铅、镉的有效态含量及生物有效性。结果表明：研究区菜地土壤铅、镉有效态平均含量为3.114,0.051mg/kg,生物有效性系数分别为7.7%,25.1%;小白菜可食部分铅、镉平均含量分别为0.123,0.021mg/kg,富集系数分别为0.4%,9.8%;从富集系数和生物有效性系数看,研究区菜地土壤镉的潜在生态风险要大于铅的。研究区菜地土壤理化性质中pH对有效态镉有显著影响;砂粒、粘粒和有机质对有效态铅含量有显著影响;铅、镉有效态与全量变化一致,全量是有效态含量的主要影响因素;土壤类型对铅、镉有效态含量有影响;在人类活动中交通对有效态铅含量有影响,肥料的施用对有效态镉含量有影响。菜地土壤中铅、镉有效态含量与小白菜可食部分铅、镉的含量相关性优于全量的,用土壤中铅、镉的有效态表征铅、镉的生态风险更准确。     

空间分析在土壤重金属污染研究中的应用

空间分析技术是土壤重金属污染研究中的一个重要工具。与经典数据统计分析方法学相比,空间分析考虑了数据的空间位置和空间关联性,能挖掘土壤重金属在二维甚至三维空间上的空间分异和时空变异特征,并对这些结果进行可视化使之以更加直观的形式呈现出来。本文概述了探索性空间数据分析(ESDA)、空间回归分析、地统计学及空间插值分析、空间随机模拟等主要空间分析理论和方法。在此基础上,综述了空间分析在土壤重金属污染调查采样设计、空间统计分析、空间变异分析及制图、土壤重金属污染来源解析及污染不确定性研究等方面的应用和研究动态,介绍了一些应用于土壤重金属污染研究的空间分析新方法,并就空间分析方法在土壤重金属研究中的应用前景和发展趋势做了展望。     

基于被动采样技术的砷有效性和界面过程研究:进展与展望

全球诸多区域均发现由于人类活动或者地质因素造成的砷污染问题,严重威胁区域生态安全和人体健康.对大尺度下砷风险有效控制,需要准确评价砷在不同介质间的界面行为.砷的迁移转化受到化学和微生物调控,从而在土水和根际等典型环境界面上,具有在毫微米尺度下形态变化剧烈的特点.传统的以破坏性取样加实验室分析为主的主动采样技术难以胜任对...     

苏南某冶炼厂周边农田土壤重金属分布及风险评价

选择江苏南部冶炼厂周边污染的水稻田,采集耕层0～15cm的土壤,分析土壤中重金属Cd、Pb、Hg、As、Zn、Cu的污染程度及其空间变异特征。结果表明,土壤Cd、Pb、Cu、Zn、Hg的全量随着距污染源距离的增加而减少,呈现由东北向西南扩散的趋势,As则是由西北向东南扩散。6种重金属中Cd、Hg的污染范围相对较大,Zn的污染范围最小。DTPA浸提的6种重金属有效态含量都是距污染源距离越远而越少。采用内梅罗综合污染指数法对土壤中的重金属进行风险评价,土壤重金属的综合污染指数为39.27,污染程度已超过5级,为重度污染,其中Cd、Hg污染最为严重,含量范围分别为3.98～44.58mg·kg-1、0.36～2.01mg·kg-1,As为中度污染,Pb、Cu、Zn则为轻度污染,说明研究区域农产品安全生产存在很大的风险。     

北京市五环内绿地土壤4种重金属的形态特征及其生物有效性

[目的]了解北京市五环内绿地表层(0—20cm)土壤重金属(Cu,Cd,Pb和Zn)的形态特征及其生物有效性,为北京市绿地土壤重金属污染防治提供比较可靠的参考依据。[方法]在建成时间为2~400a的绿化区内共采集表层土壤样品151个,运用改进BCR提取法分析样品中重金属的赋存形态,而后通过风险评价编码法(RAC)和次生相与原生相分布比值法(RSP)对重金属生物有效性进行评估。[结果]样品中重金属Cu,Cd,Pb和Zn的含量分别为31.42,0.29,29.89,76.78 mg/kg,Cu,Zn在中部和东北部含量较高,Pb在中部地区含量较高,Cd在西北部、东北部和南部存在少量高值区。Cu,Cd,Pb和Zn形态分布的总体规律均为:残渣态可氧化态弱酸溶态可还原态,稳定态含量均远高于有效态,有效态含量比例表明重金属生物有效性大小顺序为:CdZnCuPb风险评价编码法(RAC)表明,Cd和Zn环境风险程度为低风险,Cu和Pb无环境风险。次生相与原生相分布比值法(RSP)显示,Cu,Cd,Pb和Zn元素RSP值分别为0.06,0.49,0.18,0.13,土壤整体上未受到重金属污染,但是有少部分地区存在被污染现象。[结论]北京市五环内绿地土壤总体上不存在重金属Cu,Cd,Pb和Zn污染,环境风险较低,但应对重金属赋存形态保持关注。     

腐植酸钾对土壤铅化学形态、生物可给性及健康风险的影响

通过重金属分级提取和生物可给性体外模拟试验,研究了腐植酸钾对污染土壤中铅化学形态组成、生物可给性及基于生物可给性的健康风险评价的影响。结果表明,不同比例的腐植酸钾均可显著提高铅污染土壤的pH值和有机质含量,且随着添加量的增大而升高;添加腐植酸钾可显著降低土壤中弱酸提取态铅和可还原态铅含量,增加可氧化态铅和残渣态铅含量,其影响随添加量的增大而增强;土壤中铅的生物可给性随腐植酸钾添加量的增加而显著降低;基于生物可给性的人体健康风险评价显示,经口摄入铅污染土壤造成的危害水平随着腐植酸钾添加量的增大而显著降低,且儿童危害商(非致癌风险)高于成人,约为成人的1.8倍;土壤中铅的安全含量限值随腐植酸钾添加量的增大而增大,非敏感用地高于敏感用地。研究表明,腐植酸钾可有效降低铅污染土壤中铅的健康风险和生态风险,可用于铅污染土壤的修复。     

Distribution and Speciation of Chromium and Cadmium in an Organic and Inorganic Fertilized Chernozem

Fertilizers are widely applied in agricultural practice to improve crop yield and quality. However, they can also alter the behavior of soil pollutants. A field experiment was conducted on a chernozem in Heilongjiang Province, China. Various proportions of inorganic nitrogen (N), phosphorus (P), and organic (manure) fertilizers were applied. Soil samples were collected four times over 2 years, and the total concentrations and speciation of chromium (Cr) and cadmium (Cd) were analyzed. Inorganic fertilizer addition had little effect on the total concentration of Cr and Cd, while organic fertilizer addition reduced the total concentrations of both Cr and Cd. Inorganic fertilizers increased the concentration of Cr in the exchangeable form, but decreased that of the residual form (P < 0.05). Addition of inorganic or organic fertilizer alone decreased concentrations of exchangeable Cd (P < 0.05), but the combination of inorganic and organic fertilizers had the opposite effect. High concentration of total Cd exceeding the upper limits of the Environmental Quality Standard for Soils proposed by the Ministry of Environmental Protection of China could result in an environmental risk, and fertilizer application could lower that risk. Results of risk assessment code calculated as the percentage of the sum of metal concentrations in the exchangeable and carbonate-associated form in total metal concentration showed that Cr and Cd risks were lowered when organic fertilizer was applied alone or in combination with inorganic fertilizers. Our study highlighted that organic fertilizer should be applied alone or in combination with inorganic fertilizers to lower the environmental risks of Cr and Cd pollution in the chernozem.     

不同有机肥中Cu、 Zn在农田土壤中的有效性与形态归趋

【目的】畜禽粪便有机肥的施用是造成我国农田土壤重金属污染的重要原因之一。本文选用两种典型规模化养殖场畜禽粪便有机肥,研究其在石灰性土壤和酸性土壤上施用1年后Cu、 Zn的有效性和形态归趋,为客观评价畜禽粪便有机肥中重金属进入土壤后的环境行为和生态风险提供理论依据。【方法】采用温室土壤培养试验,在石灰性土壤和酸性土壤上分别设对照(CK)、 施2%鸡粪(CM2%)、 施5%鸡粪(CM5%)、 施与CM2%、 CM5%含等量Cu、 Zn的重金属无机盐溶液(CS2%、 CS5%)、 施2%猪粪(PM2%)、 施5%猪粪(PM5%)、 施与PM2%、 PM5%含等量Cu、 Zn的重金属无机盐溶液(PS2%、 PS5%)9个处理,每个处理设3次重复,在温室条件下培养1年。测定土壤pH值, EDTA提取有效态Cu、 Zn以及采用改进Tessier连续提取法提取的各形态Cu、 Zn的含量,分析鸡粪、 猪粪及等量无机盐溶液中Cu、 Zn进入土壤后的有效性和形态归趋。【结果】施用鸡粪和猪粪1年后,石灰性土壤的pH值降低,酸性土壤的pH值升高,施用5%猪粪时石灰性土壤pH值降低了0.23个单位,酸性土壤pH值升高了0.87个单位。施入鸡粪、 猪粪1年后,石灰性土壤中有效态Zn和酸性土壤中有效态Cu、 Zn含量显著增加,施用5%猪粪时酸性土壤中有效态Cu含量增加了1.95倍,施用5%鸡粪时2种土壤中有效态Cu的含量均显著低于等量无机盐。施用鸡粪和等量无机盐后,2种土壤中交换态和有机结合态Cu的含量显著增加,交换态、 碳酸盐结合态、 有机结合态和铁锰氧化物结合态Zn的含量显著增加; 施用猪粪和等量无机盐后,2种土壤中交换态、 铁锰氧化物结合态和有机结合态Cu的含量显著增加,碳酸盐结合态和铁锰氧化物结合态Zn的含量显著增加。【结论】施用鸡粪、 猪粪提高了石灰性土壤中Zn和酸性土壤中Cu、 Zn的有效性,高用量条件下鸡粪中Cu的有效性低于等量无机盐。1年后, 通过畜禽粪便有机肥带入2种土壤中的Cu 主要以交换态和有机结合态的形式存在,Zn则主要以碳酸盐结合态、 铁锰氧化物结合态和有机结合态的形式存在。2种土壤上有机肥带入的Cu、 Zn转化为铁锰氧化物结合态的比例低于等量无机盐,2种有机肥带入2种土壤中的Cu转化为交换态和有机结合态的比例高于等量无机盐。鸡粪带入的Zn转化为交换态的比例在酸性土壤中低于等量无机盐,但在石灰性土壤中则高于等量无机盐。     

Accumulation of Phosphorus and Arsenic in Two Perennial Grasses for Soil Remediation

Rice cutgrass (Leersia oryzoides Sw.) and tall fescue (Festuca arundinacea Schreb.) were assessed for potential for phytoremediation of arsenic (As) in a soil-based medium amended with phosphorus (P) in a greenhouse experiment. Arsenic was added at 30 mg kg^?1, and P concentrations ranged from 0 to 120 mg kg^?1. Plants were grown for 8 weeks. Rice cutgrass accumulated greater concentration and total amount of As in shoots or roots than fescue. Only the first increment of P fertilization increased As in shoots above that which accumulated without P fertilization. Phosphorus fertilization did not stimulate growth of either species. Most of the As remained in the roots of either species. Plant–soil accumulation ratios suggest that rice cutgrass has more potential in phytoremediation than fescue. Above a minimal amount, P fertilization did not enhance As accumulation in shoots and may not be useful in increasing the potential of either species to remediate soils.     

生物炭/石灰混施对重金属复合污染土壤的稳定化效应

采用室内模拟实验,以南方砷镉铅复合污染的酸性红壤为对象,利用化学钝化原理,探讨钝化材料对重金属稳定化的技术效果及应用配方,以期为砷镉铅复合污染红壤修复与安全利用提供依据。具体做法为：选择生物炭（BC）和石灰（SH）为钝化材料,以土壤重量的1%、4%为材料添加量,单一或混合施用于砷镉铅复合污染土壤,并于恒温（25℃）条件下培养60d,在实验进行至第1天、第30天、第60天时取样,测定红壤酸碱度（pH）和水溶态（Water soluble）有效砷（As）、镉（Cd）、铅（Pb）即WSAs、WSCd、WSPb含量,以及土壤重金属As、Cd、Pb结合态含量与占比的变化,明确生物炭石灰单/混施对重金属的稳定化效应。结果表明：生物炭/石灰无论单施或混施均能不同程度地降低土壤中水溶态WSCd和WSPb含量,钝化效率分别为33.51%～78.89%和9.05%～96.24%。而材料单施（1BC、4SH）和两者混施高用量（4BC4SH）处理,均能大幅降低土壤中有效As含量,钝化效率为10.25%～55.27%,其中以两者混施高用量（4BC4SH）处理对土壤重金属As、Cd、Pb协同钝化的效果最佳,当培养实验进行至第60天时,钝化效率依次达55.27%、76.39%和96.24%。培养后土壤中As形态由易被植物吸收的非专性吸附态、专性吸附态转化为稳定的残渣态,土壤中Cd和Pb则由活性最强的酸可提取态转化为残渣态,土壤中As、Cd、Pb的稳定化效应明显,迁移系数下降;此外,生物炭/石灰的单施及混合施用,均可导致土壤酸碱度（pH）显著提升（P<0.05）,有利于南方酸化土壤的改良。总体而言,本研究中生物炭/石灰两者混施高用量水平下（4BC4SH）土壤重金属的钝化效果最优,可实现对As、Cd和Pb复合污染红壤的稳定化修复。