A critical review of approaches to aquatic environmental assessment

As demands on aquatic resources increase, there is a growing need to monitor and assess their condition. This paper reviews a variety of aquatic environmental assessments, at local, national, international and global scales and finds confusion in the terminology used to describe assessments. In particular the terms 'ecosystem' and 'integrated' are often misused resulting in lack of clarity. Therefore, definitions of some assessment terminology are suggested, consolidating existing proposals and simplifying future applications. A conclusion from the review is that a new classification system is required. The categorisation system proposed builds on preliminary work of the International Council for the Exploration of the Sea (ICES). Assessment classification is based on the environmental components considered, methodologies and nature of the linkages between components, and the inclusion or exclusion of socio-economic factors. The assessment terminology and categorisation system provided could in future simplify the way that assessments are defined and used to inform development of management strategies.     

Multixenobiotic resistance, acetyl-choline esterase activity and total oxyradical scavenging capacity of the Arctic spider crab, Hyasaraneus, following exposure to bisphenol A, tetra bromo diphenyl ether and diallyl phthalate

The Arctic has become a sink for persistent organic pollutants (POPs) originating from lower latitudes, and relatively high levels have been found in different biota. Recent studies have identified detrimental effects on wildlife including endocrine disruption, impairment of enzyme activity, and reduced immune function. The Arctic spider crab, Hyas araneus, shown interesting potential for its use as sentinel organism in polar ecosystems. This study investigated the effect of 2,2',4,4'-tetra bromo diphenyl ether (BPDE), bisphenol A (BPA), and diallyl phthalte (DPA) on H. araneus in a three weeks exposure study. Expression of multixenibiotic resistance (MXR) proteins has been studied using the C219 monoclonal antibody which allows identifying an immunoreactive protein of 40 kDa in the digestive gland while no such protein could be observed in the gills. Expression of this protein was increased by exposure to DPA (+75%; p<0.05, n=10). All compounds significantly affected muscle acetylcholine esterase (AChE) activity (p<0.05, n=10) with 50 microg/L DPA having the strongest effect by lowering the value to 37% of control. The total oxyradical scavenging capacity measured in the digestive gland toward peroxyl, hydroxyl and peroxynitrite was also significantly reduced indicating a decreased resistance to oxidative stress generated by DPA (p<0.05, n=5). These results thus suggest the potential detrimental effects of DPA even at concentration as low as 50 microg/L on H. araneus.     

Trace metal concentrations in Antarctic sea spiders (Pycnogonida, Pantopoda)

Trace metals were analysed in sea spiders collected on two Polarstern cruises in the Weddell Sea. We found a substantial interspecific heterogeneity of Cd, Cu, Ni, and Zn, indicating varying accumulation strategies and metabolic demands for essential elements. Means and 95%-confidence intervals for all 44 samples analysed are 26+/-7 mg Cd kg(-1), 38+/-22 mg Cu kg(-1), 62+/-13 mg Ni kg(-1) and 990+/-130 mg Zn kg(-1) DW. Only for Pb do we find values less than 1.0 mg kg(-1) for most collectives analysed, in good agreement with other Antarctic arthropods such as crustaceans. Our study provides further evidence for the frequently reported "Cd anomaly" in many polar arthropods. While Cu concentrations in pantopods are within the reported range for Antarctic amphipods and decapods, Ni concentrations are exceptionally high and might be part of predation defence mechanisms. These possibilities should be investigated in more detail in future studies.     

Uptake and tissue distribution of C4-C7 alkylphenols in Atlantic cod (Gadus morhua): relevance for biomonitoring of produced water discharges from oil production

The sensitivity of different tissues for assessment of chronic low-dose environmental exposure of fish to alkylphenols (APs) was investigated. We exposed Atlantic cod (Gadus morhua) in the laboratory to tritium labelled 4-tert-butylphenol, 4n-pentylphenol, 4n-hexylphenol, and 4n-heptylphenol via seawater (8 ng/l) and via contaminated feed (5 μg/kg fish per day). Measurements of different fish tissues during eight days of exposure and eight subsequent days of recovery revealed that APs administered via spiked seawater were readily taken up whereas the uptake was far less efficient when APs were administered in spiked feed. AP residues were mainly located in the bile fluid whereas the concentrations in liver were very low, indicating a rapid excretion and the liver-bile axis to be the major route of elimination. The biological half-life of APs in the exposed cod was short, between 10 and 20 h. Our study shows that in connection with biomonitoring of AP exposure in fish, assessment of AP metabolites in bile fluid is a more sensitive tool than detection of parent AP levels in liver or other internal tissues.     

Multivariate discriminant analysis distinguishes metal- from non metal-related biomarker responses in the clam Chamaelea gallina

Molecular biomarkers are among the most sensitive and earliest responses to pollutants. However, lack of detailed knowledge on variability of responses and their possible seasonal variation limit their use. In addition, the seasonality of biological processes modulates the response of organisms to pollutant stressors. Using multivariate statistics, we have studied the influence of environmental and biological factors on the response of a battery of molecular biomarkers in the clam Chamaelea gallina collected along the South-Spanish littoral. Multivariate discriminant analysis clearly distinguished biomarker response between clean and polluted areas, using heavy metals as indicator of pollution. Such differences disappeared when the dataset was normalised for metal content, thus indicating that pollution was the main significant cause of the changes observed between clean and polluted sites. In conclusion, this work shows that, when applying a complete biomarker panel, multivariate statistical tools can be used to discern pollutant- from non pollutant-related responses.     

动三轴试验机轴向摩擦解决的研究

介绍了20 kN动三轴试验机机械工作原理,分析了该仪器轴向摩擦力的产生原因,提出了解决办法并加以具体实施.     

与地震活动相关的电磁扰动的空间观测

介绍了地震附近甚低频（VLF）电磁波信号强度统计分析结果。统计数据全部来自法国的DEMETER卫星（轨道高度700km,近太阳同步轨道）,处理中采用了稳健的两步处理方法。第一步,利用所有的观测数据构建电磁辐射背景图,在给定条件和给定轨道位置对电场波动强度进行了统计描述。第二步,在第一步得到的电场波动强度的统计分布背景基础上,对地震附近的观测数据进行分析,研究由地震活动引起的电场波动强度的变化,评估它们在统计上的显著性。在整个分析过程中,我们总计使用了大于两年半的卫星观测数据,并对在此期间全球范围内发生的大约9000个震级大于或等于4．8的地震进行了统计分析。统计结果显示,在夜间时段,对于浅源地震（震源深度小于或等于40km）,在震前0～4小时的短时间内,电场波动强度会有4～6dB的显著降低。     

浑善达克沙地的光释光年代序列与全新世气候变化

浑善达克沙地具有对气候变化响应敏感和生态环境脆弱的特点,是研究环境变化的理想地区．相对于黄土而言,沙质沉积是近源、在沉积期堆积速率快,有可能记录了某些时间段千年时间尺度的干旱事件．应用光释光测年技术,对浑善达克沙地东北．西南断面上具代表性的10个沙丘和沙／黄土剖面进行了年代测试,获得了35个样品的光释光年龄;结合野外地层观察分析和粒度、磁化率等测试,得到了浑善达克沙地全新世干旱事件和相对湿润期的气候变化记录：在距今9．9～8．2ka期问,沙地发育厚层粗砂层,沙丘处于活动状态,气候干燥,植被覆盖度低;在距今8．0～2．7ka期间,沙地发育有多层浅灰一灰黑色砂质土壤,沙丘总体上处于固定．半固定状态（也含有短时段的沙丘活化的干旱事件）,指示气候较之前明显湿润,植被相对茂密;2．3ka以来,沙地沉积物以粗砂堆积为主,沙丘又重新活化,气候总体上为干旱．通过对沙丘沉积记录和沉积产状的分析,发现浑善达克沙地在全新世早期、8．2ka前后以及小冰期时期,气候较为干旱,植被盖度小,沙丘活化;在“隋唐暖期”和“中世纪温暖期”,气候较湿润,植被发育良好,沙丘固定．具有绝对释光年龄控制的沙丘沉积记录表明,全新世浑善达克沙地多次千年时间尺度的气候事件可能是全球气候变化的区域响应．     

Variability in rainfall threshold for debris flow after the Chi-Chi earthquake in central Taiwan, China

The purpose of this study is to analyze variability in rainfall threshold for debris flow （critical rainfall for debris flow triggering） after the ML 7.3 Chi-Chi earthquake in central Taiwan in 1999. Two study sites with different geological conditions were surveyed in the earthquake area. Streambed surveys were conducted to continuously monitor debris flows between 1999 and 2006. During the 7-year study period, every debris flow event was identified, and the streambed characterized. Results show that the rainfall threshold for debris flow was remarkably lower just after the Chi-Chi Earthquake, but gradually recovered. To date, this rainfall threshold is still lower than the original level prior to the earthquake. This variability in rainfall threshold is closely related to the mount of sediment material in the initiation area of debris flow, which increased rapidly due to landslides resulting from the earthquake. With the increase in sediment material, the rainfall threshold was lowered severely during the first year following the Chi-Chi earthquake. However, heavy rainfalls mobilized the sediment material, causing debris flows and transporting sediment downstream. With the decrease in sediment material, the rainfall threshold recovered gradually over time. Furthermore, debris flows occurred only in the subbasins that had sufficient sediment material to cause significant movement. Hence, these results confirm that the sediment material in the initiation area of debris flow is a crucial component of the rainfall threshold for debris flow.     

冰岛裂谷北部阿斯基亚火山之下岩浆运动引起的下地壳地震

裂谷中的下地壳层通常由于高温而呈韧性,火山岩浆活动会引发地震。冰鸟中大西洋裂谷的特点是热流高,大量岩浆聚集成高达25～30km厚的地壳,在上部8km内常发生地震。2006年7～8月在冰岛北部裂谷带阿斯基亚火山周围布设了20台地震仪进行观测,记录到位于脆韧性边界1700次震源深度为7～8km的上地壳地震;还记录到多数以震群形式发生在其他非震层的下地壳内和完全非震层的中地壳之下14～26km的100个M1〈1．5级小地震。在2007年7～8月的重复测量中,更是观测到2倍以上的下地壳地震事件。大地测量和重力数据显示,在阿斯基亚火山下存在熔岩流,当熔岩从岩浆房通过地壳流向阿斯基亚火山的过程中引发地震,也表明在活动裂谷带中岩浆在张开的岩脉中运移几米距离可引发爆裂。