Distribution and bioaccumulation of organochlorine pesticides along the Black Sea coast

Sediment, mussel, and seawater samples were collected three times during 2001–2003 at nine sampling stations along the mid-Black Sea coast of Turkey. The samples were analyzed with GC-ECD for contents of various organochlorine pesticides (OCPs) in the environment. DDT and its metabolites were detected at concentrations significantly above the detection limits. The highest concentrations of DDT metabolites measured in the sediment and mussel samples were 35.9 and 14.0 ng/g wet weight respectively. Considerable levels of aldrin, dieldrin, endrin, heptachlor epoxide, lindane, endosulfan sulphate, and HCB were also detected in the sediment, mussel, or seawater samples. Although these persistent toxic compounds have been banned for some years in Turkey, they may still be used illegally in some regions, contributing to their significant levels in the environment. The biota–sediment accumulation factor (BSAF) estimated for DDT and its metabolites in mussels was 2.9, which is nearly two times higher than the benchmark of 1.7. In spite of such high BSAF values observed for these toxic compounds, their levels in mussels were significantly below the international legal limits recommended by the Food and Agriculture Organization of the United Nations. Edible biota from the waterbodies examined may thus still be considered safe for human consumption at this time. However, as pollutants can biomagnify through the food chain over time, further routine sampling and analysis of biota along the Black Sea coast are warranted in order to better assess the threat of OCPs to public health in the region.     

“生物有效性测量”与“全沉积物毒性识别评估(TIE)”联用有效识别出沉积物中主要致毒污染物

沉积物中污染物种类繁多,准确判断其中产生生物毒性的主要来源是个难点,本文作者先采用TIE法初步判断出主要致毒污染物为有机物和重金属(毒性描述阶段(相I)),传统的毒性单位分析结果显示Cr、Cu、Ni、Pb和Zn主要致毒重金属,而为氯氰菊酯、氯氟氰菊酯、溴氰菊酯和氟虫腈为主要致毒有机物中(毒性鉴定阶段(相II))。采用4步分级提取法和Tenax提取法分析了重金属和有机物的生物有效性。生物有效性毒性单位分析更加准确地锁定了毒性主要贡献重金属为Zn、Ni和Pb,毒性主要贡献有机物为氯氰菊酯、氯氟氰菊酯和氟虫腈。沉积物的稀释降低了重金属的毒性并使其毒性贡献鉴定变得复杂,生物有效性测量可以有效地提高TIE结果的准确性。
精选自Xiaoyi Yi, Huizhen Li, Ping Ma and Jing You. Identifying the causes of sediment-associated toxicity in urban waterways in South China: Incorporating bioavailabillity-based measurements into whole-sediment toxicity identification evaluation. Environmental Toxicology and Chemistry: Volume 34, Issue 8, pages 1744–1750, August 2015. DOI: 10.1002/etc.2970
详情请见http://onlinelibrary.wiley.com/doi/10.1002/etc.2970/full     

Nitrogen dynamics in the sediments of a wetland coastal ecosystem of southern India

The study area, Kuttanad Waters is a part of the Cochin estuarine system on the west coast of India. Kuttanad is well known for its agricultural activity and so the major contribution to the inorganic ions of nitrogen will be from fertilisers applied in agriculture. Based on observed salinity the stations have been divided into three zones. The fresh water zones had higher quantities of silt and clay whereas the estuarine zone was more sandy. The chemical speciation scheme applied here distinguishes three forms of ammoniacal nitrogen species: exchangeable, fixed, and organic ammoniacal nitrogen. No significant trends were observed in the seasonal distribution of total, exchangeable, fixed and organic nitrogen. A significant concentration of exchangeable ammonia was observed in the sediment due to their predominantly reducing environment, which restricts nitrification. High NH₄-N concentrations in the pore waters, along with the sedimentary composition leads to a significantly high quantity of fixed NH₄-N. The low values for N org is due to high mineralisation or deamination of organic nitrogen     

Impacts of mussel dredging on sediment phosphorus dynamics in a eutrophic Danish fjord

Effects of mussel dredging on sediment metabolism (oxygen uptake and sulfate reduction rates) and phosphorus dynamics (flux across sediment-water interface and sequential extraction) were examined in Limfjorden (Denmark) during spring (May) and summer (August). Sediment samples were taken during mussel dredging and in addition an experimental simulation of the dredging was performed to investigate short-term changes in phosphorus (P) dynamics. Iron-bound P was reduced by up to 2/3 in the surface layer in the dredging track (from 31 to 8?mmol?P?m^?2), whereas the dissolved P-pools and less reactive particulate pools were not affected by dredging. Sediment oxygen consumption was enhanced immediately after dredging, but returned to the initial level after 4 days (20–40?mmol?m^?2?d^?1). The enhanced consumption was attributed to reoxidation of reduced compounds released during dredging. Sulfate reduction rates were high in the area (13–15?mmol?m^?2?d^?1) and sulfides competed with P for oxidized iron resulting in low iron-bound pools in the area (<4% of total P pools). Sulfate reduction rates were stimulated by the resuspension of sediments, especially in August, where a subsurface maximum was found, possibly due to a mixing of labile organic matter into these layers. In contrast sulfate reduction rates were reduced in the dredging track due to removal of labile organic matter from the surface layers. The loss of P during dredging was to some extent counteracted by regeneration of iron-bound P pools in the surface layers. The release of P due to mussel dredging was estimated to be in the same order of magnitude as the annual loading from the catchments and point sources to Limfjorden.     

Chemical characterization of Tan‐Sui River sediment in North Taiwan

Surface sediment samples from four downstream sites of Tan‐Sui River in Taipei metropolitan area were collected from 1997 to 1999. The semivolatile organic pollutants present in the sediments were screened by GC/MSD. Several target compounds including sixteen polycyclic aromatic hydrocarbons (PAHs), seven chlorobenzenes, two phthalates and the total amount of C8‐C32 aliphatic hydrocarbons were quantified. The concentration of the 16 PAHs ranges from 0.21 to 5.69 μg/g of which fluoranthene, pyrene and phenanthrene were the highest. The concentration of the total chlorobenzenes ranged from 0.04 to 5.85 μg/g. The concentration of bis(2‐ethylhexyl)phthalate ranges from 3.8 to 35.3 μg/g and that of the total C8‐C32 aliphatic hydrocarbons ranges from 0.94 to 10.6 μg/g. Some of these values are higher than similar sediment survey in Japan in the eighties. The concentration of bis(2‐ethylhexyl)phthalate is much higher than the no‐effect level (0.184 μg/g) set by McDonald. Some of the PAHs have already reached the level of biological effects. As compared with the sediment samples collected from Tou‐Chien River and Pu‐Ze River located at the west of Taiwan, the chlorobenzene concentrations of sediments in Tan‐Sui River are 5–6 times higher, the PAHs are 6–10 times higher and the phthalates are 11–20 times higher. Nonylphenol was also commonly found in the Tan‐Sui River sediment. There is a decreasing tendency of PAHs and phthalates concentration from surface to bottom for the core sample at Taipei Bridge site. Such tendency is less obvious for chlorobenzenes.     

Determination of enzymatic activities for the characterization of sediments

In‐vivo enzymatic activity tests have been used for the characterization of sediments. Sediment samples representing three typical situations on the river Elbe and one reference site on the river Spree were investigated from March to October 1993. Fresh sediments and pore water were analyzed for their dehydrogenase and proteolytic enzymatic activities, respectively. The dehydrogenase and protease activities varied depending on sampling site, date and kind of sample. From the mean values of the dehydrogenase activities over the whole period of investigation significant differences between the sampling sites became evident. The dehydrogenase activity of pore water rather than that of the whole sediment is suitable to differentiate between anthropogenically influenced and not influenced sites. The dehydrogenase activities in the contaminated samples were extremly higher than those in the uncontaminated samples. In contrast to this, samples from the uncontaminated sites showed a considerably higher specific proteolytic activity. This fact is interpreted as a possible enzymatic inhibition.     

屠宰废水处理工程实践与工艺探讨

屠宰废水具有有机物浓度高、杂质和悬浮物多、油脂浓度高等特点,采用隔油沉淀-气浮-UASB-接触氧化的主体处理工艺对屠宰废水进行处理,取得了较好的处理效果,出水达到GB 13457—92《肉类加工工业水污染物排放标准》的二级排放标准。     

海水中氯氟烃的气相色谱法测定

应用气相色谱法测定海水中氯氟烃,海水用Niskin采水器采集,将海水转移玻璃注射器中储藏直到分析。把大约30mL海水引入到一个玻璃气提器中,用高纯氮气将溶解在海水中氯氟烃(CFC's)吹扫出来浓缩在冷捕集器中,然后把捕集器加热,用高纯氮气CFC's送入气相色谱分离柱,CFC's由电子捕获检测器(ECD)检测出。结果表明:该方法快速,灵敏度高,分离效果好,适用于分析测定水体中氯氟烃。     

Development of models for predicting toxicity from sediment chemistry by partial least squares-discriminant analysis and counter-propagation artificial neural networks

There is strong interest in developing tools to link chemical concentrations of contaminants to the potential for observing sediment toxicity that can be used in initial screening-level sediment quality assessments. This paper presents new approaches for predicting toxicity in sediments, based on 10-day survival tests with marine amphipods, from sediment chemistry, by means of the application of Partial Least Squares-Discriminant Analysis (PLS-DA) and Counter-propagation Artificial Neural Networks (CP-ANNs) to large historical databases of chemical and toxicity data. The exploration of the internal structure of the developed models revealed inherent limitations of predicting toxicity from common chemical analyses of bulk contaminant concentrations. However, the results obtained in the validation of these models combined relevant values of non-error classification rate, sensitivity and specificity of, respectively, 76, 87 and 73% with PLS-DA and 92, 75 and 97% with CP-ANNs, outperforming the results reported for previous approaches.