Mercury distribution,speciation and potential ecological risk assessment in sediments from Lake Taihu,China

Abstract

Twenty-one surface sediments collected from seven surroundings areas of Lake Taihu in two different years were analyzed for total mercury (THg) concentrations, physicochemical characteristics and speciation using a sequential extraction method to assess spatial distribution, sources, and potential ecological risk. Surface sediments from Lake Taihu contained elevated levels of Hg in two sampling years with THg levels ranging from 77 to 346?ng/g (mean 145?ng/g) in October 2010 and ranging from 122 to 573?ng/g (mean 266?ng/g) in November 2012, respectively. The mean THg concentrations in all studied surface sediments exhibited an increasing trend over time. The oxidizable fraction (F3) and residual fraction (F4) were the predominant Hg species in sediments, while more mobile Hg phases of acid-soluble fraction (F1) and reducible fraction (F2) made up less than 0.5% THg. Significant relationships were found between total organic carbon (TOC) and THg and geochemical speciation indicating an important role for organic matter in affecting distribution, mobility, and bioavailability of Hg in sediments. As evidenced by Hakanson’s potential risk index the total ecological risk of Hg was low in the entire Lake Taihu in 2010 but considered moderate in Zhushan Bay, West Coast, and Meiliang Bay in 2012. These findings provide conservation managers with information needed to more effectively regulate the environment of Lake Taihu.     

Metal partitioning in sediment pore water from the Ondo coastal region,Nigeria

Distribution and equilibrium partitioning of metals (Cd, Cu, Cr, Fe, Ni, Pb, Mn, and Zn) between pore water and surface sediments at the Ilaje coast of Ondo State, Nigeria, were studied. The Ilaje River can be one of the interesting research locations because of its economic nature and history of oil pollution. Seasonal variations were observed to investigate possible variations in the availability of metals for organisms throughout the year. The concentrations in both sediments and pore water during the dry and wet seasons were as follows: Cu?>?Fe???Mn?>?Pb?>?Ni?>?Cr?>?Cd?>?Zn. The pore water–sediment partition coefficient (K _p) showed that Zn and Cd were highly mobile while Fe and Cu have restricted mobility. Dissolved organic carbon (DOC) in pore water had a strong influence on mobility and bioavailability of all the metals (p?K _oc), increased levels of Fe and Cu were linked to lithological origin. Concentrations of Pb and Ni were associated with petroleum-related sources. The significance of the field-based techniques for ecotoxicological purposes is discussed.     

Cd,Pb, and Cu in water and sediments and their bioaccumulation in freshwater fish of some lakes in Hanoi,Vietnam

The seasonal variations of Cd, Pb, and Cu in the water, sediments, and freshwater fish (Hypophthalmichthys molitrix, Cirrhinus molitorella, and Oreochromis mossambicus) of four lakes in Hanoi, Vietnam, were investigated. Samples for analysis were taken four times from April 2010 to March 2011. The levels in water were lower than the Vietnamese standards, except for Pb, but they were all much higher than the Canadian standards for protection of aquatic life; in the sediments, they were higher than world average levels. Bioaccumulation of the three metals in fish was site-dependent and species-dependent, but correlations of their levels in fish to those in water and sediments were weak. Levels of Pb in fish exceeded those of the UK and the WHO standards, and the recommended values of Vietnam for human consumption. Overall, the results show that the lakes are polluted with these metals, and consumption of high quantities of fish from them may be problematic. The outcome of this research helps to establish background data for future monitoring.     

Pesticides in the aquatic environment ‐ experiences from Austrian monitoring programmes

The present paper deals with the impact of pesticides on water quality in Austria. Results of different monitoring programmes and surveys concerning the contamination of groundwater and running waters are provided; various aspects of sediment analyses and bioindication are also discussed. The evaluation of the data reveals a rather serious situation particularly in the eastern parts of the country intensively used by agricultural activities. The substances most often detected are triazines and lindane. Legal measures and key figures on the Austrian agriculture are also presented.     

上海市河网水体中As的分布特征及其生态风险评价

2012年4月,在上海市河网采集表层水和沉积物样品各53个,测定其As含量,并采用潜在生态风险指数法对沉积物As的污染状况进行了评价。研究结果表明,上海市河网表层水和沉积物中As的含量分别为0.47～8.84μg·L-1和3.72～12.65μg·g-1,其中表层水中As的浓度处于中国地表水环境质量标准Ⅰ类水平,沉积物中As的浓度有15个样点超过了上海市土壤背景值,但均低于欧盟标准推荐值;表层水中As的浓度与pH呈显著正相关,说明pH值影响河水中As的迁移和转化;沉积物中As的浓度与总有机碳含量呈显著性正相关,说明沉积物中的As主要与总有机碳结合在一起;潜在生态风险评价结果显示,上海市河网沉积物中的As属于低生态风险。     

Adsorption of sulfonamides on lake sediments

Sulfonamides (SAs) are one class of the most widely used antibiotics around the world. Their fate and transport in the aquatic environment is of great concern. In this study, adsorption of four SAs—sulfadiazine (SD), sulfamethoxazole (SMZ), sulfadimethoxine (SDM) and sulfamethazine (SM2)—in single-solute and multi-solute systems on sediments of Dianchi (DC) Lake and Taihu (TH) Lake, China was investigated with batch experiments. In the single-solute adsorption system, the Langmuir model and the dual-mode model described the adsorption process better than the Freundlich model. Model fitness was better on DC sediment than on TH sediment. The order of adsorption capacity approximately followed a decreasing order of SDM>SD>SM2>SMZ on both sediments, which was likely attributed to the distinctly different water solubility of the four SAs. In the multi-solute system, the order of adsorption capacity was SM2>SDM>SD>SMZ, which was probably related to the compound speciation caused by the pH values of the experimental solution. In the multi-solute system, both competitive and cooperative adsorption played important roles in the adsorption of sulfonamides on sediments.     

彩塘电镀区底泥重金属污染与释放特征

采集了彩塘不锈钢电镀区河段9个典型底泥样品,研究了底泥重金属含量及其地球化学形态以及底泥在不同pH值下的释放特征,并探索了碱石灰对底泥重金属的固定效果.研究表明,该区域底泥中Cr、Cu、Cd、Ni、Pb、Zn大大超过了广东省土壤背景值,其中Cu、Cd、Cr、Ni超过了《土壤环境质量标准》(GB15618—1995)二级标准的4.4、3.7、1.6、5.3倍.底泥中的重金属迁移性的大小为Cd>Zn>Ni>Pb>Cu>Cr.重金属释放是长期持续过程,随着水体pH值降低,底泥重金属释放量逐渐升高.底泥中加入碱石灰能有效地降低重金属的生物有效性,减少底泥重金属释放.     

水体沉积物中石油类物质释放过程动力学研究

模拟水体沉积物中石油类物质向水相中释放的动力学过程,探讨在不同石油污染强度下,石油物质在水相中饱和浓度的变化。研究结果表明:上述过程可以用滞膜模型进行描述,释放过程为典型的一级动力学过程,沉积物中石油含量与水相中石油的释放浓度呈正向关系,在相同的释放条件下,污染强度越高,水相中石油的饱和浓度越高,释放速度也越快。     

太湖草型区与藻型区沉积物中聚磷菌富集试验研究

采用序批式反应器(SBR)小型反应装置,以葡萄糖和丙酸为碳源,在厌氧/好氧条件下,对太湖草型区和藻型区的沉积物进行聚磷菌富集培养。探讨了太湖草型区和藻型区沉积物中聚磷菌的存在性和差异性。试验结果表明,通过实验室模拟条件培养,发现太湖沉积物存在聚磷细菌。两种碳源培养的草型区沉积物厌氧释磷量高于藻型区。以葡萄糖为碳源培养的草型区和藻型区沉积物厌氧释磷现象微弱,好氧磷的超量吸收现象比活性污泥弱,对PO34--P的平均去除率分别为34.95%、38.17%。而在以丙酸为碳源的系统中,有着明显的厌氧释磷和好氧摄磷现象,对PO34--P的平均去除率分别为41.27%、51.35%。     

Aliphatic and polycyclic aromatic hydrocarbon contamination in surface sediment of the Chitrapuzha River,South West India

Distribution (seasonal and spatial) of aliphatic and polycyclic aromatic hydrocarbons (PAHs) in surface sediments of the Chitrapuzha River, Cochin, India, was investigated using gas chromatography. Significantly high concentrations prevailed during the pre-monsoon season with the industrial zones of the river appearing to be hot spots with particularly elevated levels of the hydrocarbons. AHCs ranged between 7754 and 41,173?ng/g with an average of 25,256?ng/g, while total PAHs varied from 5046 to 33,087?ng/g. n-Alkane indices and PAH diagnostic ratios point to petroleum contamination in the sediments. The significance of PAHs in the sediments was explored using universally accepted interpretation tools. Observed levels of PAHs in sediments of Chitrapuzha are likely to cause adverse effects on biota.