Distributions, cycling and recovery of amino acids in estuarine waters and sediments

Acid hydrolysis of estuarine water samples for the determination of amino acids (AAs) was tested and found to be effective at high (250 μM) nitrate concentrations when the anti-oxidant, ascorbic acid, was added to the samples. Hydrolysable AA concentrations were then determined in surface sediments collected from low and high salinity regions of the Tamar Estuary (UK) during winter 2003 and 2004, and in overlying water when simulated resuspension of sediment particles was performed. Concentrations of AAs in sediment samples comprised <50% of particulate nitrogen, fitting the paradigm that most sedimentary nitrogen is preserved within an organic matrix. When sediment samples were resuspended in overlying water (salinity 17.5), the rapid, measured increase in dissolved AA concentrations almost equalled the reported nitrate concentration in the lower estuary, with the subsequent decrease in the total dissolved AA levels suggested that bacterial uptake was occurring. Our data concur with previous studies on nitrogen desorption from sediments and suggest that an understanding of organic nitrogen cycling will be an important aspect of future effective estuarine management.     

大庆地区主要排水干渠水质和底质遗传生物毒性测试的探索

探讨了用蚕豆根尖细胞微核技术测试大庆地区主要排水干渠水质及底质的遗传毒性.并且通过污染指数PI值来研究水质底质的的综合毒性.结果表明作为一种灵敏度高、成本低廉的生物毒性监测方法,将在环境监测领域中有着广阔的应用前景.     

苏州河底泥中污染物分布特征及相关性

通过对苏州河市区段底泥的分析测定与研究，揭示了涉是金属，耗氧有机物，无机有害非金属和有毒有害有机物的若干相关性，以及它们的含量在各断面，统一断面的各深度和不同点位之间的分布的共同特征和规律性。     

苏州河底泥的耗氧量

对苏州河底泥耗氧量(SOD)的实验测定结果表明,苏州河底泥(北新泾下游)的夏季耗氧强度是冬季的6倍,最大强度发生在武宁路河段,达7500mg/m2     

黄河水体沉积物对邻苯二甲酸二甲酯的吸附

为探讨黄河水体沉积物对邻苯二甲酸二甲酯(DMP)的吸附能力，用批量平衡法研究了沉积物与DMP的吸附作用。结果表明吸附等温线符合Freundlich方程，通过回归分析，分别得出20℃和15℃DMP在黄河水中的等温方程Cs=0．3488×Ceq0.7799和Cs=0．3354×Ceq0.7849。因指数项常数小于1，说明沉积物对DMP的吸附不随溶液中DMP的浓度成正比例增加。黄河水体沉积物对DMP有一定的净化能力。     

底泥耗氧速率的测定方法比较

在对实验室法和现场法测定底泥耗氧速度（SOD）的步骤和操作参数综述中，对于实验室测定法。从底泥采样，测定容器，实验底泥厚度，上覆水，测定培养条件，溶解氧测定方法，溶解氧测定时间和测定间隔，空白样的测定以及SOD的计算等方面作了介绍；对于现场测定法，从测定容器，测定水力条件，溶解氧测定方法，空白水样的测定，溶解氧测定时间和测定间隔，SOD的计算方法等方面作了介绍，最后在原理，技术和费用上对以上2种方法加以比较。     

Effect of intermittent aeration mode on nitrogen concentration in the water column and sediment pore water of aquaculture ponds

Nitrogen in pond sediments is a major water quality concern and can impact the productivity of aquaculture. Dissolved oxygen is an important factor for improving water quality and boosting fish growth in aquaculture ponds, and plays an important role in the conversion of ammonium-nitrogen (NH₄⁺-N) to nitrite-nitrogen (NO₂^?-N) and eventually nitrate-nitrogen (NO₃^?-N). A central goal of the study was to identify the best aeration method and strategy for improving water quality in aquaculture ponds. We conducted an experiment with six tanks, each with a different aeration mode to simulate the behavior of aquaculture ponds. The results show that a 36 hr aeration interval (T_c = 36 hr: 36 hr) and no aeration resulted in high concentrations of NH₄⁺-N in the water column. Using a 12 hr interval time (T_c = 12 hr: 12 hr) resulted in higher NO₂^?-N and NO₃^?-N concentrations than any other aeration mode. Results from an 8 hr interval time (T_c = 8 hr: 8 hr) and 24 hr interval time (T_c = 24 hr: 24 hr) were comparable with those of continuous aeration, and had the benefit of being in use for only half of the time, consequently reducing energy consumption.     

Distribution and contamination of metals and biogenic elements in sediments from Zhifu Bay of the Yellow Sea, China

Metals and biogenic elements were analyzed from surface sediments of sixteen stations and a 32 cm core collected from Zhifu Bay in July 2009. High concentrations of biogenic silica (BSi) reflected the high diatom productivity in the Bay. Meanwhile, total organic carbon (TOC) in Zhifu Bay was mainly from terrestrial sources. All metals were lower than the marine sediment quality guidelines. Based on the vertical profiles of biogenic elements, there was a clear increase of TOC, total nitrogen (TN), and total phosphate (TP) between 1985 and 2000. TN concentrations decreased after the start of the operation of the sewage treatment plant in 1998; however TOC and BSi remained at high levels. Metal concentrations showed a general increase from the bottom to the top of the core. Most anthropogenic metals reached a maximum during 1996 and 2000, and decreased after the startup of the sewage plant; however, they have increased again recently. The results from correlation analysis and principal component analysis show that industrial pollution is the main source of Cd, Cr, Cu, Ni, Pb and Zn contamination in Zhifu Bay, and Yantai Port and ship transportation also contribute a lot to Cd, Cu, Hg, and Pb pollution.     

Temporal and spatial changes of microbial community in an industrial effluent receiving area in Hangzhou Bay

Anthropogenic activities usually contaminate water environments, and have led to the eutrophication of many estuaries and shifts in microbial communities. In this study, the temporal and spatial changes of the microbial community in an industrial effluent receiving area in Hangzhou Bay were investigated by 454 pyrosequencing. The bacterial community showed higher richness and biodiversity than the archaeal community in all sediments. Proteobacteria dominated in the bacterial communities of all the samples; Marine_Group_Ⅰ and Methanomicrobia were the two dominant archaeal classes in the effluent receiving area. PCoA and AMOVA revealed strong seasonal but minor spatial changes in both bacterial and archaeal communities in the sediments. The seasonal changes of the bacterial community were less significant than those of the archaeal community, which mainly consisted of fluctuations in abundance of a large proportion of longstanding species rather than the appearance and disappearance of major archaeal species. Temperature was found to positively correlate with the dominant bacteria, Betaproteobacteria, and negatively correlate with the dominant archaea,Marine_Group_Ⅰ; and might be the primary driving force for the seasonal variation of the microbial community.