Spatial and temporal trend of sewage pollution indicated by coprostanol in Macao Estuary,southern China

Bottom sediments and a ²¹⁰Pb dated sedimentary core in Macao Estuary were quantitatively analyzed with GC-MS for coprostanol and other sterols. Higher coprostanol concentrations were detected at Port Interior and Lower Qianshan River, indicative of serious sewage pollution from densely populated Macao Island and Zhuhai City. However, very low concentrations of coprostanol were detected around Coloane Island as well as Port Exterior and Maliuzhou River except sites adjacent sewage outlets. Coprostanol pollution in Macao Estuary originates mainly from locally direct discharge of untreated wastewater. The concentrations of coprostanol in ZJ-9 were mainly in range of 150–280 ng/g with an average of 210 ng/g for more than 20 years from early 1970s to early 1990s. However, it increased obviously since 1993, and reached the highest in 1995–1996. However, a sharp decrease of coprostanol concentration from 470 to 31 ng/g after 1996 was observed corresponding to the first wastewater treatment plant in Taipa Island going into action.     

砂粒粒径与砂层厚度对单体筐养养殖系统中三疣梭子蟹(Portunus trituberculatus)幼蟹摄食行为与生长特性的影响研究

建立了以经过遗传改造的发光细菌Acinetobacter sp. RecA为受试物种的环境污染物遗传毒性快速检测方法,该方法最快可在3h内得到毒性评价结果。采用该方法评价了环渤海排污口12份污水样品的遗传毒性。环渤海12个排污口的污水样品均表现出了不同水平的遗传毒性,并呈现出一定的分布特征。其中,高毒水质集中出现在山东半岛污水样品中,中毒水质集中出现在辽东半岛地区,而低毒水质主要集中于京津冀地区。综上,在环渤海的污水样品遗传毒性检测中,这种新型发光细菌法具有快速、灵敏、简便等优点,为以后近海环境的水质生物毒性检测提供了参考依据,具有应用于近海环境水质快速监测与评价的潜力。     

Survey of estrogenic and androgenic disruption in Swedish coastal waters by the analysis of bile fluid from perch and biomarkers in the three-spined stickleback

The potential for endocrine disruption close to sewage treatment plant and pulp mill effluent discharge points along the Swedish Baltic Sea coast was explored using a dual survey strategy employing two stationary fish species. The levels of vitellogenin and spiggin as biomarkers of endocrine disruption were determined in juvenile three-spined sticklebacks (Gasterosteus aculeatus L.) together with the sex ratios and the presence of intersex. As an indication of exposure, estrogenic and androgenic substances were analysed by GC–MS in bile from perch (Perca fluviatilis L.). Spiggin and vitellogenin levels in juvenile three-spined sticklebacks were generally low, and, for most sampling sites no deviation in gonad type ratios were observed. No remarkable levels of natural or synthetic estrogens or androgens were observed in bile fluid from perch, while bisphenol A and 4-nonylphenol were detected in perch from both reference sites and exposed sites. Taken together, the results did not indicate estrogenic or androgenic disruption in the investigated waters.     

Heavy metal contamination in western Xiamen Bay sediments and its vicinity, China

Concentrations of selected heavy metals (Cu, Pb, Zn, Cd, Cr, Ni and Fe) in surface sediments from nine sites in western Xiamen Bay and its vicinity were studied in order to understand current metal contamination due to urbanization and economic development in Xiamen, China. The sediment samples were collected in December 2004 and July 2005 respectively in order to examine temporal variations. In this study, we found that heavy metal concentrations in surface sediments sampled in the western Xiamen Bay and adjacent Maluan Bay and Yuandang Lagoon varied from 19 to 97mg kg(-1) for Cu, 45 to 60mg kg(-1) for Pb, 65 to 223mg kg(-1) for Zn, 0.11 to 1.01mg kg(-1) for Cd, 37 to 134mg kg(-1) for Cr, 25 to 65mg kg(-1) for Ni and 3.08 to 4.81% for Fe. Although all metal concentrations in sediments meets Chinese National Standard Criteria for Marine Sediment Quality, both metal enrichment factors (EF) and geoaccumulation index (I(geo)) show that Pb contamination exists in the entire study area and contamination of other metals are also present in some locations depending on the sources, of which sewage outlets and commercial ports are the main sources of contaminants to the area. This study shows that using the sediment quality standard criteria only to assess sediments cannot properly reflect sediment contamination. A multiple approaches should be applied for the sediment quality assessment.     

A trophic model for the Danshuei River Estuary, a hypoxic estuary in northern Taiwan

The estuary of the Danshuei River, a hypoxic subtropical estuary, receives a high rate of untreated sewage effluent. The Ecopath with Ecosim software system was used to construct a mass-balanced trophic model for the estuary, and network analysis was used to characterize the structure and matter flow in the food web. The estuary model was comprised of 16 compartments, and the trophic levels varied from 1.0 for primary producers and detritus to 3.0 for carnivorous and piscivorous fishes. The large organic nutrient loading from the upper reaches has resulted in detritivory being more important than herbivory in the food web. The food-chain length of the estuary was relatively short when compared with other tropical/subtropical coastal systems. The shortness of food-chain length in the estuary could be attributed to the low biomass of the top predators. Consequently, the trophic efficiencies declined sharply for higher trophic levels due to low fractions of flows to the top predators and then high fractions to detritus. The low biomass of the top predators in the estuary was likely subject to over-exploitation and/or hypoxic water. Summation of individual rate measurements for primary production and respiration yielded an estimate of −1791 g WW m⁻² year⁻¹, or −95 g C m⁻² year⁻¹, suggesting a heterotrophic ecosystem, which implies that more organic matter was consumed than was produced in the estuary.     

干湿循环与初始静偏应力耦合作用下城市污泥固化土动力累积变形特性

城市污泥固化土用作路基填料,对于节约工程成本、保护环境等具有重要意义。本文以城市污泥固化土为研究对象,利用DDS动三轴仪,从干湿循环次数、初始静偏应力、动应力3个方面研究其对累积塑性应变及动强度特性的影响。试验结果表明:在干湿循环单独作用下,土体累积塑性应变随干湿循环次数的增加先增大后趋于稳定,但与初始静偏应力耦合作用下对土体累积塑性应变的影响不太显著。动应力对其影响较大,且存在临界值:当动应力小于临界值时,累积塑性应变呈现出先增大后逐渐稳定的趋势; 当动应力大于临界值时,累积塑性应变在达到某一振次后快速增大,土体迅速产生变形破坏。干湿循环与初始静偏应力都会降低土体的动强度,但干湿循环在达到10次后,动强度将趋于平稳,不再受其影响。通过回归分析,建立了考虑干湿循环次数、初始静偏应力及动应力等因素影响的城市污泥固化土稳定型累积塑性应变模型,并验证了其可行性。     

Transformation of ammonium nitrogen and response characteristics of nitrifying functional genes in tannery sludge contaminated soil

High concentrations of ammonium nitrogen released from tannery sludge during storage in open air may cause nitrogen pollution to soil and groundwater. To study the transformation mechanism of NH₄⁺-N by nitrifying functional bacteria in tannery sludge contaminated soils, a series of contaminated soil culture experiments were conducted in this study. The contents of ammonium nitrogen (as NH₄⁺-N), nitrite nitrogen (as NO₂^?-N) and nitrate nitrogen (as NO₃^?-N) were analyzed during the culture period under different conditions of pollution load, soil particle and redox environment. Sigmodial equation was used to interpret the change of NO₃^?-N with time in contaminated soils. The abundance variations of nitrifying functional genes (amoA and nxrA) were also detected using the real-time quantitative fluorescence PCR method. The results show that the nitrification of NH₄⁺-N was aggravated in the contaminated silt soil and fine sand under the condition of lower pollution load, finer particle size and more oxidizing environment. The sigmodial equation well fitted the dynamic accumulation curve of the NO₃^?-N content in the tannery sludge contaminated soils. The Cr(III) content increased with increasing pollution load, which inhibited the reproduction and activity of nitrifying bacteria in the soils, especially in coarse-grained soil. The accumulation of NO₂^?-N contents became more obvious with the increase of pollution load in the fine sand, and only 41.5% of the NH₄⁺-N was transformed to NO₃^?-N. The redox environment was the main factor affecting nitrification process in the soil. Compared to the aerobic soil environment, the transformation of NH₄⁺-N was significantly inhibited under anaerobic incubation condition, and the NO₃^?-N contents decreased by 37.2%, 61.9% and 91.9% under low, medium and high pollution loads, respectively. Nitrification was stronger in the silt soil since its copy number of amoA and nxrA genes was two times larger than that of fine sand. Moreover, the copy numbers of amoA and nxrA genes in the silt soil under the aerobic environment were 2.7 times and 2.2 times larger than those in the anaerobic environment. The abundance changes of the amoA and nxrA functional genes have a positive correlation with the nitrification intensity in the tannery sludge-contaminated soil.     

冻融作用下污泥固化轻质土动力特性及结构演化

冻融作用会影响污泥固化轻质土动力特性和结构特性。为研究不同冻融循环次数和冻结温度下的污泥固化轻质土动力特性及结构演化,对冻融循环作用后的污泥固化轻质土进行动三轴试验和固结试验。试验结果表明:在冻融循环作用下,污泥固化轻质土动应力-应变曲线呈弱应变硬化型。污泥固化轻质土动强度和变形随着冻融次数（n）的增加和冻结温度（T）的降低而减小。经历前4次冻融作用后,对固化土变形和动强度影响较大,经历8次冻融循环后基本趋于稳定。冻融循环对土体动力特性的影响本质上是对土体结构性的影响。固化土冻融结构势（m_dσn）的变化规律与动强度类似,随冻融次数的增加和冻结温度的降低而下降。冻融循环次数是影响污泥固化轻质土动力特性和结构性的主要因素,冻结温度为次要因素。     

陈化污泥理化特性对泥饼渗透性的影响研究

开展陈化污泥渗透特性研究对于填埋库污泥脱水减量作业具有重要指导意义。选取了8种不同陈化条件下的污泥,开展了压缩排水试验,测定了陈化污泥上清液中可溶性有机物含量和类型,以及陈化污泥聚合体粒径分布与滤液的Zeta电位,并通过皮尔逊相关性分析研究了陈化污泥各物理化学特性间的相互作用。结果表明,随着上清液中可溶性有机物含量的减少、相对腐质化程度的增高与滤液Zeta电位绝对值的增大,陈化污泥的可渗透性增大。同时,当陈化污泥聚合体趋于稳定和粒径增大时,包裹在聚合体中的有机物不易释放到上清液中,陈化污泥可渗透性增大。另外,由于陈化环境的影响,陈化污泥总有机含量变化与上清液中有机物含量变化缺乏一致性,依据陈化污泥有机质含量判断渗透性会造成错误。最后,建立了陈化污泥比阻的影响模型,对于预处理过程中如何改善陈化污泥渗透性具有参考意义。     

污水源热泵技术在城市住宅供暖中的应用研究

随着城市的发展和能源需求的增长,污水的热能回收利用越来越受到关注,开发污水源热泵技术对建筑节能降耗具有重要意义。本文就污水源热泵系统的工作原理、特点等方面进行了介绍,阐述了国内外污水源热泵技术的开发利用历程与工程现状,分析了城市污水热能资源潜力以及污水源热泵技术的发展前景,指出利用污水与环境的温差获取热能具有十分巨大的能量资源前景,适宜的热源距离是污水源热泵开发利用的先决条件,开发污水源热泵系统,可以充分利用城市污水处理厂的二级出水或城市污水作为水源,通过合理利用出水的流量和温差为城市住宅供暖。基于我国能源与环境的现状,污水源热泵系统具有良好的市场前景,是一种值得推广的能源开发利用方式。