水体沉积物重金属生物有效性及评价方法

在研究以重金属为主要污染物的水体中,通常把沉积物视为探索环境重金属污染的工具。由于沉积物中重金属化学行为和生态效应的复杂性,对沉积物中重金属生物有效性的研究是当前学术界的热点研究课题。本文就沉积物中重金属的生物有效性及沉积物质量评价方法作了简要评述。包括沉积物对水生生物的作用机理,孔隙水重金属浓度的估算,沉积物质量评价方法,沉积物质量基准。     

海河流域水体沉积物中多氯联苯污染特征及风险评价

截至目前,尚没有研究从流域尺度系统分析海河流域水体沉积物中多氯联苯(PCBs)的污染特征及风险水平。以海河流域7大河系及典型湖库为研究对象,基于文献中PCBs的数据统计,从流域尺度探讨了不同水体沉积物中PCBs的组成和其空间分布特征,并利用潜在生态危害指数法和毒性当量法评价其生态风险。结果表明,海河流域水体沉积物总PCBs污染呈"北高南低"趋势。二氯联苯至十氯联苯在海河流域中都有不同程度的检出,主要以低氯原子数的二氯联苯至五氯联苯为主。海河流域沉积物中PCBs毒性主要取决于PCB-126和PCB-169。两种生态风险评价方法评价结果存在一定的不确定性,需将两种方法结合,进行综合判断。     

白洋淀水中铜、铅的化学形态及其分布

前言 目前,我们在评价水体受重金属污染的现状,以及重金属对水生动植物的毒性作用或生物效应时,一般都是以金属的总浓度作指标,但这往往会获得令人误解的结果.重金属对水生动植物的毒性作用取决于其化学形态,例如铜对永生物的毒性是随其络合程度的增强而减弱的,铅和锌也有同样表现.通过研究重金属的化学形态,可以为水体质量评价提供有意义的数据并可较     

汞吸附研究进展

汞是常温常压下唯一以液态存在的金属,由于其高挥发性和剧毒性,排放到环境中容易造成严重的污染。而且,长期暴露在汞含量超标的环境中对人体具有极大的伤害。主要综述了当前应用吸附法治理气体、水体和土壤中汞污染的研究进展,并指出生物吸附技术是今后治理重金属污染的重要发展方向。     

污染水体的生物修复技术研究进展

详细介绍了污染水体生物修复技术的特点 ,综述了近年来国内外水体生物修复技术的研究和应用现状 ,并评述了水体生物修复技术存在的问题以及污染水体生物修复的发展方向     

红枫湖沉积物大容积高水位条件下薄层覆盖材料的污染原位控制效果

为使薄层覆盖专用沉积物污染原位控制材料能较好地运用到湖泊沉积物污染原位治理现场,以红枫湖污染沉积物为研究对象,构建了大容积高水位的沉积物污染释放的原位控制实验装置,测定了沉积物污染控制材料应用后2~18 d内上覆水体中常规富营养化指标及金属元素的浓度,综合分析了沉积物污染原位控制效果。结果表明,应用2种材料进行原位控制后,上覆水体p H和EC值均较稳定,与对照组相比没有显著差异。材料1施用后的2~18 d内上覆水体中一直未检出TP,材料2施用后的2~18 d内上覆水体仅第12天检出TP(0.01 mg/L),未施用控制材料的对照组在2~18 d内上覆水体TP均为高检出,TP峰值出现在第10天(0.17 mg/L);施用控制材料后的2~18 d内控制组上覆水体COD多介于《地表水环境质量标准》(GB3838-2002)Ⅱ类(≤15 mg/L)~Ⅲ类(≤20 mg/L)之间,部分时段未检出,相比之下对照组上覆水体COD多高于Ⅴ类标准限值(≤40 mg/L)且变幅大;材料1施用后的2~18 d内上覆水体中NH3-N浓度较低但波动较大,材料2施用后的2~18 d内上覆水体中NH3-N波动小但浓度较高。2种控制材料施用后上覆水体金属元素浓度在2~18 d内均在标准限值内,说明薄层覆盖专用控制材料及方法可安全高效地应用于湖泊沉积物污染原位控制,具有一定的工程应用价值和前景。     

用SOS/Umu生物测试评价北方某自来水厂对遗传毒性物质的去除效果

大量研究表明,饮用水中存在着能导致遗传毒性的物质,在我国许多水厂水质检测能力有限的前提下,生物毒性指标作为反映有毒物质综合指标具有重要的现实意义.本研究应用SOS/Umu生物毒性测试评价了北方某市一自来水厂的A、B、C、D 4套试验工艺在不同的季节(冬春两季)各工艺段出水的遗传毒性效应.结果显示,冬春两季地表水加氯后遗传毒性效应均显著增加,冬季间接遗传毒性效应高于春季;活性炭吸附对去除遗传毒性物质效果显著,但后期加氯使遗传毒性效应增加;冬春两季比较,以及地下水和地表水比较,各工艺出水的遗传毒性效应差别很大.通过研究表明,本研究所应用的生物毒性测试SOS/Umu能够快速、准确地对水厂工艺过程中致突变物质的处理效果进行评价,能对工艺改进提出指导,是自来水质安全性评价的重要补充手段.     

大辽河主要污染源重金属特征及污染评价

为了解大辽河水环境中重金属污染来源及其污染程度,对大辽河上游来水以及主要排污口的表层水体和表层沉积物主要重金属(Cr、Co、Cd、Mn、Zn、Ni、Cu、Pb、As)浓度进行了研究,并分别采用综合污染指数评价法和地累积指数评价法对表层水体和表层沉积物污染程度进行了评价。结果表明,大辽河上游来水中Cr、Cd、Zn、Cu、As、Pb元素浓度均低于《地表水环境质量标准》(GB 3838—2002)Ⅰ类标准规定的限值;太子河中Cr、Co、Ni、Cu、Zn、Cd、Pb元素浓度较高,海城河Mn、As元素浓度较高;主要排污口水体中Cr、Cu、As、Cd、Pb元素浓度均低于GB 3838—2002的Ⅰ类标准规定的限值,其中纱厂潮沟、港监潮沟排污口水体重金属浓度较高。大辽河沉积物重金属浓度表现出自上游向下游递减的特征,西潮沟、港监潮沟排污口沉积物重金属浓度高于其他排污口。综合污染指数评价法表明,大辽河水质情况较好,太子河存在较高的潜在污染风险;而地累积指数评价法表明,大辽河主要汇入河流和主要污染源沉积物重金属污染程度大多为清洁,只有西潮沟排污口沉积物中As处于轻度污染,需要引起注意。     

水体重金属稳定性的问题

在天然水体中,重金属污染物大多以沉积物为其最终归宿.相对水相而言,底沉积物固相浓缩重金属的倍数可高达数千至数万倍. 已知存在于底沉积物或悬浮沉积物中的重金属污染物具有不同的结合形式,其生物可给性也具有明显的差别,如沉积物间隙水中溶解态重金属被认为是最迅速生物可给     

底泥疏浚对五里湖沉积物生物毒性的影响

为评价疏浚对太湖五里湖沉积物毒性的影响,采用淡水沉积物重金属质量基准和发光细菌试验法对疏浚前后太湖五里湖沉积物的生态毒性风险进行了分析.结果显示,疏浚后,尽管沉积物中Cu和Zn的总体含量降低至毒性效应低值(TEL/TEC)以下,Cr、Pb和Ni等重金属的总体含量降低至毒性效应最高值(PEL/PEC)以下,但沉积物提取液对发光菌的毒性却显著增加,且在疏浚后1个月时毒性最大,其EC25和EC50最小,分别仅为0.51%和9.16%.这表明,疏浚尽管可有效减少沉积物中重金属污染物总体含量,但并不能完全消除沉积物的生态毒性风险;相反,还有可能导致其生态毒性的风险性进一步增加.     

A model compound study: the ecotoxicological evaluation of five organic contaminants employing a battery of marine bioassays

This paper describes the ecotoxicological evaluation of five organic contaminants frequently detected in marine sediments (tributyltin, triphenyltin, benzo[a]pyrene, fluoranthene, and PCB 153) using three marine species (Vibrio fischeri, Tetraselmis suecica, and Tisbe battagliai). The sensitivity of each species varied for all compounds. The triorganotins were consistently the most toxic to all species. The applicability of each test system to assess the acute toxicity of environmental contaminants and their use in Toxicity Identification Evaluation (TIE) is discussed. Suitability of the Microtox and T. battagliai tests for employment in TIE studies were further assessed through spiking experiments with tributyltin. Results demonstrated that the most effective treatment to remove organotin toxicity from the sample was the C18 resin. The results of this study have important implications for risk assessment in estuarine and coastal waters in Ireland, where, at present the monitoring of sediment and water quality is predominantly reliant on chemical analysis alone.     

Toxicity characterisation of sediment porewaters collected from UK estuaries using a Tisbe battagliai bioassay

The lethal toxicity of sediment porewater isolated from samples collected from six United Kingdom estuaries was tested using a Tisbe battagliai bioassay. A selection of Phase 1 toxicity identification evaluation (TIE) procedures was then used to characterise the substances responsible for the measured toxicity. In samples collected in 2000, cationic metals, ammonia, organic compounds were identified as the cause of toxicity in the most toxic sample collected. Some of the toxicity remained uncharacterised. It was shown that the toxicity in samples collected from the same locations in 2001 was due to ammonia. The successful application of the T. battagliai bioassay demonstrates that it is a suitable assay for marine sediment porewater TIE and that combined with simple characterisation procedures allow an initial assessment to be made on the type of substances responsible for the measured toxicity.     

Selective removal of organic contaminants from sediments: a methodology for toxicity identification evaluations (TIEs)

Aqueous slurries of a test sediment spiked with dibenz[a,h]anthracene, 2,4,5,2',4',5'-hexachlorobiphenyl, p,p'-DDE, or phenanthrene were subjected to decontamination experimentation. The spiked sediments were agitated at elevated temperatures for at least 96 h in the presence of either of the two contaminant-absorbing media: clusters of polyethylene membrane or lipid-containing semipermeable membrane devices (SPMDs). The effects of treatment temperature and surface area of media on the removal of contaminants were explored. This work is part of a larger methodology for whole-sediment toxicity identification evaluation (TIE). A method is being sought that is capable of detoxifying sediments with respect to organic contaminants while leaving toxicity attributable to inorganic contaminants unaffected.     

Microscale Toxicity Identification Evaluation (TIE) for interstitial water of estuarine sediments affected by multiple sources of pollution

Estuaries in the world are affected by different contamination sources related to urbanisation and port/industrial activities. Identifying the substances responsible for the environmental toxicity in estuaries is challenging due to the multitude of stressors, both natural and anthropogenic. The Toxicity Identification and Evaluation (TIE) is a suitable way of determining causes of toxicity of sediments, but it poses difficulties since its application is labour intensive and time consuming. The aim of this study is to evaluate the diagnosis provided by a TIE based on microscale embryotoxicity tests with interstitial water (IW) to identify toxicants in estuarine sediments affected by multiple stressors. TIE showed toxicity due to different combinations of metals, apolar organic compounds, ammonia and sulphides, depending on the contamination source closest to the sampling station. The microscale TIE was able to discern different toxicants on sites subject to different contamination sources. There is good agreement between the results indicated in the TIE and the chemical analyses in whole sediment, although there are some disagreements, either due to the sensitivity of the test used, or due to the particularities of the use of interstitial water to assess the sediment toxicity. The improvement of TIE methods focused on identifying toxicants in multiple-stressed estuarine areas are crucial to discern contamination sources and subsidise management strategies.

     

Assessment of decadal changes in sediment contamination in a large connecting channel (Detroit River,North America)

Concentrations of selected heavy metals (Cd, Cu, Hg, Pb, Zn) and organic contaminants (PCBs, PAHs) were investigated in samples from the Detroit River (Great Lakes, North America) in 1999 and 2008/09 collected using a stratified random sampling design. Getis–Ord geospatial analysis was used to further establish locations of areas demonstrating significantly high and low contaminant concentrations in the river. Based on the stratified random sampling design, a majority of the examined metals and organic contaminants demonstrated little or no trends with respect to regional sediment concentrations and river-wide mass balances over the investigated time interval. The Getis–Ord analysis revealed local scales of contaminated and clean areas which did not conform to the original strata used in the geostatistical sampling design. It is suggested that geospatial analyses such as Getis–Ord be used in the design of future sediment quality surveys to refine locations of strata that can simultaneously address sediment recovery over system-wide, regional and local spatial scales.     

Passaic river sediment interstitial water phase I toxicity identification evaluation

A suite of tests was conducted to evaluate and identify the cause or causes of toxicity in Passaic River sediments. Sediment toxicity was measured with three types of bioassays: a whole sediment bioassay with the marine amphipod, Ampelisca abdita, and interstitial water bioassays with A. abdita and the bioluminescent bacterium Vibrio fisheri (Microtox((R))). In addition, a Phase I Toxicity Identification Evaluation (TIE) was conducted to elucidate the cause of observed toxicity. Analytical concentrations of selected residues in whole sediment and interstitial water from the five sampling stations were considered in conjunction with the conclusions drawn from the toxicity tests and Phase I TIE results. Finally, a toxic units approach was used to evaluate the predicted toxicity of measured interstitial water residue concentrations. There was a lack of toxic response in the short-term interstitial water bioassays, indicating that oxidants, soluble forms of metals, and dissolved phase neutral organics were not likely toxicants. However, there was significant toxicity indicated by the whole sediment A. abidita bioassays. After 10 days, there was complete or near complete mortality in amphipods exposed to all of the sediment samples tested. Removal of interstitial water toxicity by filtration was common to all four stations that exhibited measurable initial toxicity. The observed toxicity characteristics are consistent with particle associated neutral organics. This conclusion is supported by toxicity removal via filtration, lack of toxicity in the Microtox((R)) assays, and the fact that whole sediments were more toxic than was interstitial water.     

Chemical and bacterial changes during laboratory conditioning of formulated and natural sediments

Within the framework of toxicity testing using formulated sediment, a conditioning treatment prior to toxic contamination has been examined. This preliminary step enables the bacterial colonisation of the sediment, the initiation of organic matter degradation, and the establishment of stable biological and physico-chemical conditions. The treatment involved in keeping the formulated sediment under water in conditions similar to that chosen for toxicity tests. The behaviour of a formulated sediment was compared with a natural sediment. The monitoring of physico-chemical and biological parameters of sediment and water column was carried out over a 30-day incubation in two laboratories. The parameters of pH and redox, dissolved organic carbon (DOC), NH4 and NO2, total organic carbon (TOC) were measured. The bacterial community was characterised by the determination of bacterial density, in total bacteria number or colony forming units (CFU), several exoenzymatic activities (P-glucosidase, xylosidase, leucine-amino-peptidase phosphatase and sulfatase activities), and three gas productions (CO2, N2O and CH4). The same experiment was carried out with a natural sediment. A 10- to 15-day conditioning allowed a physico-chemical stabilisation and corresponded to kinetic changes in hydrolysis activities. As compared to data of the natural sediment, the biological activity of the formulated sediment showed a different dynamic with lower activity levels. For both sediments, an important decrease of activities levels was observed after 15 days because of a substrate limitation. The work showed that a preliminary conditioning treatment of a formulated sediment provides the stabilisation of parameters that can affect toxicant bioavailability. Additional research is needed to determine the real influence of conditioning on the bioavailability of contaminants. The possible advisability of organic matter input, to maintain the sediment bacterial activity, has to be studied.     

Toxicity evaluation of organic sediment extracts resolved by size exclusion chromatography using rainbow trout hepatocytes.

The (geno)toxicity of sediment dichloromethane extracts and fractions obtained by size exclusion chromatography were evaluated to investigate effects based on size fractionation. In this study, three sediments were selected according to their incremental contamination in PAHs and in PCBs: Hamilton harbour, Toronto bay and lake St. Clair sediments. Heavy metals, total sulfur and elemental sulfur (S8) were also determined in the (un)fractionated sediment extracts. The liver cells were exposed to concentrations of sediment extracts and fractionated samples for 24 h at 15 degrees C, afterwhich cell viability, cytochrome P4501A1 activity, available free Zn, DNA damage and oxidative stress were determined. The results showed that the sediment extracts contained high levels of sulfur most of which was found in the low molecular weight (LMW) region, i.e., the 2000-50 atomic mass unit (amu) fraction. Elemental sulfur (S8) accounted for 14-41% of extractable sulfur and were found to elute in the post-column volume (PCV) fraction despite its molecular weight of 256 amu. Heavy metals were found mainly in the HMW (i.e. the > 2000 amu) fraction and LMW fractions and very few or none were observed in the PCV fractions. In sediment extracts, sublethal effects were present principally by the HMW and LMW fractions suggesting that some chemicals were also associated with high molecular weight compounds of extractable organic matter. Less toxicity or effect was sometimes found in the extract indicating an antagonistic effect of the contaminants. We found that cell viability and genotoxicity evaluations could be performed on the unfractionated extracts while EROD, available Zn and oxidative stress measurements should be performed on the LMW fractions because of possible antagonist or shielding effects. Considering the cytotoxic responses, the best toxicity ranking in respect to contaminant levels in sediment extract was obtained with the LMW and PCV fractions which accounted for most of the toxic responses in the chromatographic fractions. Moreover, the shielding effect could be explained, in part, by the association of LMW contaminants to large macromolecules.     

Seasonal variation of sediment toxicity in the Rivers Dommel and Elbe

Contaminated sediment in the river basin has become a source of pollution with increasing importance to the aquatic ecosystem downstream. To monitor the temporal changes of the sediment bound contaminants in the River Elbe and the River Dommel monthly toxicity tests were applied to layered sediment and river water samples over the course of 10 months. There is an indication that contaminated sediments upstream adversely affected sediments downstream, but this process did not cause a continuous increase of sediment toxicity. A clear decrease of toxic effects in water and upper layer sediment was observed at the River Elbe station in spring related to high water discharge and algal blooms. The less obvious variation of sediment toxicity in the River Dommel could be explained by stable hydrological conditions. Future monitoring programmes should promote a more frequent and intensive sampling regime during these particular events for ecotoxicological evaluation.     

Arsenic residue in residential area after cleanup of pesticide illegal dumping sources in Thanh Hoa province,Central Vietnam

In Vietnam, Nicotex's site is perhaps the most infamous case of illegal disposal of toxic pesticides near residential areas. In 2013, affected villagers discovered illegal burials of around 1,000 tons of expired pesticides in the Nicotex factory. Organic pesticides were detected in illegal burial areas (IBAs) around 60 times greater than acceptable levels, but no attention was paid to contamination of metals, metalloids, and other classes of organic contaminants, which could be co-contaminants in pesticide formulation. This study assessed the contaminants remaining in the IBAs and surrounding residential areas two years after the source removal conducted in 2014. Additionally, a preliminary health risk assessment from residual contaminants was performed. Nine classes of chemicals including parental pesticides, inorganic and organic degradation byproducts, and metals and metalloids, comprising 123 chemicals were quantified in soil, sediment, and water samples from Nicotex and surrounding residential areas. Although concentrations of organic pesticides were below acceptable levels, arsenic contamination in the soil in a Nicotex IBA named NCT5 and Nap village (NV) exceeded the acceptable level. The enrichment factor and log-probability plot indicate that arsenic enrichment at NV is not from natural sources but is associated with arsenic contamination in NCT5. Arsenic may be a co-contaminant in pesticide manufacturing or an arsenical pesticide, such as monosodium methanearsonate. Arsenic found in NV was toxic arsenate for which the preliminary risk assessment yielded an unacceptable excess carcinogenic risk (1 × 10^?4). While all attention was paid to investigate and treat contamination of organic pesticides, it turns out that arsenic is the major existing threat which poses an unacceptable cancer risk in good agreement with the high cancer rate claimed by villagers near Nicotex. This justifies the need for further investigation of the extent of the arsenic contamination and restoration of the contaminated land.