典型棕地修复前后土壤重金属生态风险变化——以江西贵溪冶炼厂为例

目前,我国对于棕(褐)地周边区域生态风险的研究较少,且主要是针对风险源带来的潜在危害进行评价,没有考虑风险受体能够承受生态风险能力的大小,生态风险评价研究不全面。在棕(褐)地周边区域的生态风险评价中加入风险受体的相关研究,主要从风险源的危害分析和风险受体的生态脆弱性两方面对生态风险进行评价,使评价更加全面,另外,现有研究少有对生态风险在时间上的变化研究,考虑了生态风险时间上的变化,对贵溪冶炼厂周边两个时期的生态风险进行评价并分析其变化,利用GIS软件对评价结果进行空间表达,对研究区域存在的生态风险空间差异进行分析。结果表明:修复前苏门区、九牛岗、水泉区、串山垅等地区存在很强生态风险,沈家-林家区和长塘周家区的生态风险相对较小,处于中等风险水平,修复后研究区的生态风险大大降低,很强风险降为强风险水平,中等风险降为低风险,说明修复方式比较有效,但仍有小范围区域存在较强风险,应加强修复,研究区域中耕地的生态脆弱性最大。对于生态脆弱性较大且生态风险较大的区域应进一步进行修复治理,生态脆弱性大而生态风险较低的地区应加强监测防范,防止再次发生较强风险。     

淮河安徽段水及沉积物中重金属的研究

对采集淮河安徽段水及沉积物样品,利用ICP-AES进行重金属分析,结果表明砷、铅、铬超标,在沉积物中的含量最多。研究区域的重金属开始富集于生物体内,已对水生态系统及水产品安全产生影响,应进一步加强检测工作,以便及时采取相应防治对策。     

Heavy metals' contamination in sediments of Wadi Al-Aqiq water reservoir dam at Al-Baha region,KSA: Their identification and assessment

Sediments are the ultimate sump for heavy metal pollutants. The main purpose was to investigate the ecological and health risk assessment of heavy metals in the sediments of Wadi Al-Aqiq water reservoir. The metals detected were arranged in decreasing order Fe > Mn > Cr > Cu > Zn > Ni > Co > Pb. Pearson correlation analysis indicated strong positive association and significant linear relation between various pairs of metals. Different evaluation indices used indicated that source of contamination from lithogenic sources and sediments can be classified as low polluted quality. A comparison of the concentrations of metals with International Sediment Quality Guidelines criteria showed that only Cu and Ni concentrations above the ERL and below the ERM guideline values suggest possible adverse effects. On comparing with US Environmental Protection Agency prepared sediment quality criteria it indicated that Pb and Zn have concentrations below the non-polluted criteria, Fe, Mn, and Ni lies in the range of moderately polluted criteria, and Co and Cu are within the heavily polluted criteria. Non-carcinogenic risk quantification indicated health concern from ingestion route and no health effects for dermal exposure. On considering additive effect, the dermal exposure may cause health harm. The carcinogenic risk assessment for lead and chromium showed an acceptable risk to human health.     

Pollution,source, and ecological risk assessment of trace elements in surface sediments of Lake Aktaş, NE Turkey

This study applies ecological indices to determine the anthropogenic-based metal enrichment and potential ecological and ecotoxicological risks posed by each metal in the sediments of Lake Akta?, NE Turkey. Sediment samples were collected from nine stations (St1–St9) within the Turkish boundary of Lake Akta? and the heavy metal, total organic carbon %, CaCO₃%, chlorophyll degradation products (chlorophyll-α), total sulfur %, and total phosphate % contents in the sediment samples were determined. Enrichment factor (EF), pollution load and potential ecological risk (PER) indices were calculated to shed light on the ecological effects of heavy metals. The metal content was ranked in descending order of Al > Fe > Mn > Zn > Ni > Cr > Cu > Pb > As > Cd > Hg. The EF values ranged 0.87–1.0 for Cu, 1.04–1.14 for Pb, 1–1.08 for Zn, 0.88–0.95 for Ni, 0.99–1.24 for Mn, 0.89–0.93 for Fe, 0.82–1.01 for As, 0.96–1.19 for Cd, 0.94–1.0 for Cr, and 1.42–1.90 for Hg. Minimal contamination was found for Hg. Pollution load, PER, and toxic risk indices indicated no ecological risk currently. However, considering the PER index for metals individually, a moderate potential risk was detected for Hg. The data obtained from multivariate statistical analyses indicate that Hg and Mn originate from the atmosphere, while other elements have lithogenic sources.     

Distribution,speciation, and ecological risk assessment of heavy metals in surface sediments of Jiaozhou Bay,China

This paper analyzed the distribution and speciation of seven heavy metals in sediments in Jiaozhou Bay. The ecological risk was assessed using three index approaches (i.e., risk assessment code (RAC), contamination factor (CF), and potential ecological risk index (PERI)) and by a comparison with sediment quality guidelines (Chinese Marine Sediment Quality Standards (CMSQS), and threshold effect level (TEL) and probable effect level (PEL) from the USEPA). Pb, Cr, As, Cu, Zn, and Hg contents at most sites were above the corresponding TEL and Class I criteria (CMSQS) value. Particularly, high contents of Cu, detected at sites S₇ (124.5 mg kg^?1) and S₈ (118.3 mg kg^?1), exceeded the respective PEL value, indicating that harmful biological effects might occur. Speciation analysis, individual CF, and RAC calculations suggested that Cd had the highest bioavailable fraction and thus posed a very high risk to aquatic ecosystem; Cu and Zn showed a medium–high risk. Both global CF and PERI analysis indicated a high pollution risk at sites S₇, S₁, S₃, and S₂, but the assessments of specific sites were different. The incomplete consistency suggested that it is necessary to consider both total contents and chemical speciation for providing a more realistic appraisal for the risk of heavy metals in sediments.     

A direct solid‐phase assay specific for heavy metal toxicity. I. methodology

We have developed a direct toxicity assay for soils, sediments and sludges that is specific for heavy‐metal toxicity. In the assay, a β‐galactosidase‐producingstrain of Escherichia coll is mixed with the solids sample together with a small volume (1.0 ml/0.5 to 1.0 g of solids) of eluent Extraction of metals from the solids sample is not required. Controls run with the assay eliminate interference due to indigenous β‐ga‐lactosidase activity or interaction between the solid matrix and the chromaphore. Use of 0.1 M sodium nitrate as eluent was found to yield somewhat higher sensitivity to heavy metals in solid‐phase samples than MilliQ water. Application of the assay to a diverse array of soils, sludges, and sediments indicated that samples from industrial sites were generally more toxic than those from residential or commercial sites. Heavy‐metal toxicity was correlated with the copper and zinc content of solids samples, but toxicity varied considerably at the lower range of metal contents. The proposed solid‐phase assay should prove useful as a screening test for heavy‐metal toxicity in soils, sediments, and sludges. It can also help distinguish between heavy metals and organic chemicals as the cause of toxicity in solid‐phase samples.     

The determination of heavy metals in water,suspended materials and sediments from Langat River,Malaysia

The distributions of heavy metals in the Langat River were studied for a period of six months between September 1984 and February 1985. Heavy metals such as arsenic, cadmium, cerium, cobalt, chromium, caesium, lanthanum, rubidium, antimony, scandium, thorium and zinc were determined in water, suspended materials and sediment samples from the Langat River by neutron activation and atomic absorption spectrometry. The concentrations of arsenic, cadmium, cerium, cobalt, scandium, antimony, and zinc were generally highest in the suspended materials, whereas the concentrations of chromium, rubidium and thorium were always highest in the sediments: Arsenic concentrations in the river were slightly higher than the natural concentration, while other elements were generally at their natural concentration levels. The use of arsenical herbicides in plantations along the river could be a source of arsenic pollution.     

河口潮间带沉积物重金属累积及生态风险评价

于2015年7月份在闽江口鳝鱼滩湿地布设两条样带(T1和T2),并分别选取5个采样点采集沉积物样品。因重金属Co和V对动物和人类会造成一定危害,且闽江河口潮间带Co和V的研究较少,则对其理化性质、Co和V的空间分布特征以及污染程度等进行了研究,旨在为Co和V的污染研究提供参考。结果显示,该沉积物中Co和V的平均浓度分别为15.19 mg/kg、102.94 mg/kg,均高于福建省背景浓度,与其他河口对比,Co和V浓度处于中等水平。Co和V的含量由陆向海方向略有下降。地累积指数法分析得出沉积物中Co含量呈现轻度污染状态,V呈现无污染状态。此外,Co和V的潜在生态危害系数E_rⁱ分别为7.24—14.85和1.47—4.17,表明潜在生态危害轻微,闽江河口潮间带沉积物中Co和V属于轻度污染。     

Factors influencing the potential mobility and bioavailability of metals in dried lake sediments

Abstract

Samples taken from polluted creek sediments were dried at temperatures between 20°C and 100°C (either in air or under a nitrogen atmosphere) and selective chemical extraction procedures were then used to examine the effect of drying temperature and oxidation on the bonding mode distribution patterns of Zn, Pb, Cd and Cu. Exposure to air during the drying stage tended to increase the fraction of total metal which was less firmly bound (i.e. ion exchangeable, weakly sorbed). Less metal was present in these categories when higher drying temperatures were used, and temperature changes had a larger effect when the samples were dried under nitrogen. The drying process appears to promote metal migration to phases having a stronger bonding power. In most of the samples studied, heating caused Pb to migrate to the carbonate phase while accumulation in the organic/sulfide phases was the dominant process for Cu and Cd. In the case of Zn, migration to the carbonate phase was favoured in some studies (e.g. using air-dried samples), in other sediments the migration end-point was the organic/sulfide phases. During storage of dried samples at room temperature for prolonged periods (e.g. months) the amount of less firmly bound metal tended to increase, and nullified the distribution changes induced by drying. The effect was most pronounced in the case of Cd. The study highlights that significant errors in metal distribution pattern analyses can arise from sample preparation procedures and it has provided information on the possible mobilisation of metal when dredged sediment is land-dumped, i.e. allowed to dry in air.     

黄河尾闾河道及河口区水体与悬浮颗粒物重金属和砷沿程分布及生态风险

基于2016年汛前和汛后获取的黄河尾闾河道与河口区(低盐区)表层和底层水体和悬浮颗粒物样品,研究了水体和悬浮颗粒物中重金属(Cr、Ni、Cu、Zn、Pb、Cd)和As含量的沿程分布特征,并评估了其生态风险。结果表明,汛前尾闾河道表层水体中仅Cd的平均含量高于河口区,而底层水体中As、Cr、Cu、Ni和Pb的平均含量均高于河口区;汛后尾闾河道表层水体中仅Ni的平均含量低于河口区,而底层水体中6种重金属和As的平均含量均高于河口区。汛前尾闾河道表层悬浮颗粒物中As、Cd、Cu、Ni、Pb和Zn的平均含量均低于河口区,而底层悬浮颗粒物中6种重金属和As的平均含量均低于河口区;汛后尾闾河道表层悬浮颗粒物中6种重金属和As的平均含量均高于河口区,而底层悬浮颗粒物中As、Cd、Cr、Cu和Pb的平均含量均高于河口区。汛前和汛后尾闾河道及河口区表层和底层水体中重金属和As污染较轻,其值大多分别低于地表水环境质量Ⅰ类标准和海水水质Ⅰ类标准限值。相对于汛前,汛后尾闾河道及河口区表层或底层悬浮颗粒物中As和6种重金属的毒性单位之和(∑TUs)和平均PEL商数值均降低,说明汛期调水调沙工程的实施可降低汛后悬浮颗粒物中上述元素综合作用所产生潜在生态毒性风险。     

Model for instream regulation of radioisotopes and heavy metals in riverine waters subjected to a uranium mill discharge

In the Athabaska sandstone region of northern Saskatchewan, mining and milling of uranium-bearing ore is subjecting, and will continue to subject, surface waters to inputs of soluble heavy metals and uranium and thorium decay series radioisotopes. A mathematical simulation model was developed to assess the role of riverine sediments in regulating soluble concentrations of heavy metals and radioisotopes released to the environment through treated mining and milling process effluents. Specific elements studied included As, Ni, Pb, U, and Ra-226. The model considered that diffusion into sediment porewater and adsorption by sediment particulates from sediment porewater were the two dominant mechanisms regulating sediment loading. Experiments indicated that the equilibrium adsorption behaviour of the heavy metals and radioisotopes studied could be adequately explained using a linear adsorption isotherm, over the range of concentrations expected in the environment. Experimentally determined linear isotherm slopes ranged from 200 ml g⁻¹ to 21 000 ml gl. Diffusion into the effective depth of the sediments (20 cm) was modelled using a quadratic (second order) driving force and a corresponding mass transfer coefficient. The model coefficients were calibrated using field and laboratory data. Results of the modelling suggested that the sediments have a small effect on instream concentrations during the active phases of mining and milling. The sediments were predicted to accumulate sufficient adsorbed mass, during the operational phase of mining and milling, to act as a distributed instream source after completion of milling activities. The significance of this post-operational source was a function of the initial effluent loading, elapsed time and site specific river characteristics.     

Distribution of zinc-tolerant bacteria in stream sediments

The distribution of zinc-tolerant bacteria in sediments from three stream sites containing high (3125 g g^–1), medium (291 g g^–1), and low (109 g g^–1) concentrations of Zn was determined. Zinc tolerance was estimated by the ability of bacteria to grow on media amended with Zn concentrations ranging from 4 to 512 mg 1^–1. The presence of Zn-tolerant bacteria was correlated with the degree of heavy metal contamination; this correlation was more closely associated with readily extractable heavy metal concentrations than with the more rigorously extracted heavy metals. Low concentrations of Zn in media (4 to 16 mg 1^–1) were stimulatory to growth of bacteria from contaminated sites while concentrations as low as 4 mg 1^–1 were inhibitory to bacteria from the control site.     

乐安江沉积物中金属污染的潜在生态风险评价

选择污染严重的乐安江河流沉积物为对象,利用风险因子Ｅ和风险指数ＲＩ等定量诊断工具开展沉积物中重金属污染的潜在生态风险评价。根据风险指标体系和空间分异规律,将流域划分居不同特征的４种生态风险功能区。对比评价效果。潜在生态风险评价与地积累 情况大同小异,可以相互补充和借鉴。