Spatial Extent Of Degraded Sediment Quality In Puget Sound (Washington State, U.S.A.) Based Upon Measures Of The Sediment Quality Triad

A survey was designed and conducted to determine the severity, spatial patterns, and spatial extent of degraded sediment quality in Puget Sound (Washington State, USA). A weight of evidence compiled from results of chemical analyses, toxicity tests, and benthic infaunal analyses was used to classify the quality of sediments. Sediment samples were collected from 300 locations within a 2363 km² area extending from the US/Canada border to the inlets of southern Puget Sound and Hood Canal. Degraded conditions, as indicated with a combination of high chemical concentrations, significant toxicity, and adversely altered benthos, occurred in samples that represented about 1% of the total area. These conditions invariably occurred in samples collected within urbanized bays and industrial waterways, especially near the urban centers of Everett, Seattle, Tacoma, and Bremerton. Sediments with high quality (as indicated by no toxicity, no contamination, and the presence of a relatively abundant and diverse infauna) occurred in samples that represented a majority (68%) of the total study area. Sediments in which results of the three kinds of analyses were not in agreement were classified as intermediate in quality and represented about 31% of the total area. Relative to many other estuaries and marine bays of the USA, Puget Sound sediments ranked among those with minimal evidence of toxicant-induced degradation.     

Incidence of stress in benthic communities along the U.S. Atlantic and Gulf of Mexico coasts within different ranges of sediment contamination from chemical mixtures

Synoptic data on concentrations of sediment-associated chemical contaminants and benthic macroinfaunal community structure were collected from 1,389 stations in estuaries along the U.S. Atlantic and Gulf of Mexico coasts as part of the nationwide Environmental Monitoring and Assessment Program (EMAP). These data were used to develop an empirical framework for evaluating risks of benthic community-level effects within different ranges of sediment contamination from mixtures of multiple chemicals present at varying concentrations. Sediment contamination was expressed as the mean ratio of individual chemical concentrations relative to corresponding sediment quality guidelines (SQGs), including Effects Range-Median (ERM) and Probable Effects Level (PEL) values. Benthic condition was assessed using diagnostic, multi-metric indices developed for each of three EMAP provinces (Virginian, Carolinian, and Louisianian). Cumulative percentages of stations with a degraded benthic community were plotted against ascending values of the mean ERM and PEL quotients. Based on the observed relationships, mean SQG quotients were divided into four ranges corresponding to either a low, moderate, high, or very high incidence of degraded benthic condition. Results showed that condition of the ambient benthic community provides a reliable and sensitive indicator for evaluating the biological significance of sediment-associated stressors. Mean SQG quotients marking the beginning of the contaminant range associated with the highest incidence of benthic impacts (73–100% of samples, depending on the province and type of SQG) were well below those linked to high risks of sediment toxicity as determined by short-term toxicity tests with single species. Measures of the ambient benthic community reflect the sensitivities of multiple species and life stages to persistent exposures under actual field conditions. Similar results were obtained with preliminary data from the west coast (Puget Sound).     

Monitoring nekton as a bioindicator in shallow estuarine habitats

Long-term monitoring of estuarine nekton has many practical and ecological benefits but efforts are hampered by a lack of standardized sampling procedures. This study provides a rationale for monitoring nekton in shallow (<#60; 1 m), temperate, estuarine habitats and addresses some important issues that arise when developing monitoring protocols. Sampling in seagrass and salt marsh habitats is emphasized due to the susceptibility of each habitat to anthropogenic stress and to the abundant and rich nekton assemblages that each habitat supports. Extensive sampling with quantitative enclosure traps that estimate nekton density is suggested. These gears have a high capture efficiency in most habitats and are small enough (e.g., 1 m²) to permit sampling in specific microhabitats. Other aspects of nekton monitoring are discussed, including spatial and temporal sampling considerations, station selection, sample size estimation, and data collection and analysis. Developing and initiating long-term nekton monitoring programs will help evaluate natural and human-induced changes in estuarine nekton over time and advance our understanding of the interactions between nekton and the dynamic estuarine environment.     

Distribution and partitioning of trace metals in sediments of the lower reaches of the New Calabar River,Port Harcourt,Nigeria

The distribution of trace metals in sediments of the lower reaches of the New Calabar River, Nigeria was evaluated togetherwith the partitioning of their chemical species between fivegeochemical phases. Samplings were made in five zones at the lower reaches of the New Calaber River. All the trace metals were determined by AAS after selective chemical extractions andconcentrations given in g gm^-1 (dry weight basis). The average totalconcentrations found for trace metals in the sediment were (mean ± rsd.) Pb: 41.6 ± 0.29, Zn: 31.60 ± 0.42, Cd: 12.80 ± 0.92, Co: 92 ± 0.25, Cu: 25.5 ± 0.65 and Ni: 3.2 ± 0.25. Maxima and minima concentrations are inconsistent with previous studies in other rivers of this region. Spatial distribution revealed that the sources of trace metals into theriver appeared to be of non-point. Five contamination indices were applied in studying the partitioning of the trace metals inthe sediment. These indices provided bases for ascertaining the potential environmental risk of trace metals in the river system.The results denote high partition levels in the more mobile andmore dangerous phases.     

悬浮液进样石墨炉原子吸收法直接测定土壤、底泥中的铅、镓、钴、镍

介绍一种悬浮液进样直接测定土壤、底泥中多种微量金属元素的快速分析方法。基体改进剂的使用，适宜的原子化温度的选择，使用水相标准溶液作校准曲线成为可能．对标准作品的测定证明了此方法的精密度和准确度较好，适合于常规环境样品分析．     

吹气—吸收法测定废水中硫化物

对吹气－吸收法测定废水中硫化物进行了吸收试验，提出了用去离子除氧水配制硫化物标液，可增加其稳定性；用ＩＳＯ硫化物吹脱器取代普通气吸收装置，可提高硫化物回收率。试验结果表明，改进后方法的精密度，准确度及适用怀强垃令人满意。     

广西来宾栖霞组缺氧沉积环境地球化学特征

地层的岩石地球化学特征是判断其形成环境氧化还原条件的重要手段之一。本文对广西来宾铁桥剖面栖霞组中层纹状灰岩和含泥质灰岩进行地球化学分析 ,结合栖霞组沉积学和古生态学特征 ,对栖霞组沉积环境进行了探讨。岩石微量元素含量、黄铁矿矿化程度 (DOP值 )、痕量元素V/Cr、Ni/Co、U/Th、V/(V +Ni)等比值的研究结果显示 ,研究区具有缺氧沉积成因的地球化学特征。     

虾塘残饵腐解对养殖环境影响的研究Ⅱ.虾塘底层残饵腐解对沉积物环境的影响

通过室内模拟实验，研究了虾塘过量残饵的分解过程、池底硫化物的生成原理、沉积物中硫化物的积累与扩散过程和还原条件下虾病发生的可能性。结果显示，在３个月的实验时间内，硫化物可渗透沉积物５ｃｍ深度。静止５ｄ即可耗尽池底溶解氧。在虾饵腐解还原环境中，异养细菌总数达２０３×１０６个／ｇ，弧菌数达６８０×１０４个／ｇ，已达到发生红腿病程度     

黄河中游水保措施对入黄干支流泥沙特性的影响:Ⅱ.减沙效益分析

应用文献［１］关于不同地貌类型及不同水保措施条件下黄河干支流中泥沙粒径分布的研究结果,可以对相应条件下的减沙效益进行有效的分析。利用文献［１］模型,本文不仅探讨了在给定地貌类型条件下各类水保措施实施前后流域汇入黄河干支流的泥沙总量的变化,而且还在扣除降雨变化的影响之后,预测了各类组合条件下非均匀泥沙中减沙效果最佳的粒径级和相应粒径级泥沙的减沙量,预测结果得到了黄河干支流各站所有实测资料的验证。文中还简要讨论了人类活动（主要是开矿）对减沙效益的影响。     

黄土高原丘陵沟壑区坡面-沟道系统中的高含沙水流(Ⅱ)--泥沙存储-释放及降雨、径流特征的影响

以黄河中游多沙粗沙区子洲径流站和离石王家沟试验站的径流场观测资料为基础，对黄土高原丘陵沟壑区坡沟系统中高含沙水流特征进行了研究。研究表明，在坡面-沟道系统中，存在着泥沙的存贮-释放机制，这一机制与非高含沙水流和高含沙水流不同的输沙行为有关。当水流为非高含沙水流时，来自坡面和悬移质泥沙中的粗粒部分可在沟道中发生沉积；当为高含沙水流时，前期沉积的粗粒泥沙将因沟道高含沙水流强烈的侵蚀搬运作用而发生释放。降雨对坡沟系统高含沙水流的形成关系密切。在冲沟次降雨最大含沙量与雨强的关系中，表现出两个临界值。超过第一个临界值以后，含沙量急剧增大；超过第二个临界值之后，则出现极限含沙量，即含沙量不再随雨强的增大而增大。