遥感增强图像在变质岩地区构造特征研究和找铁矿中的应用

本文以地质体的波谱特性测试资料为基础, 结合地质调查和地球物理资料, 选择不同的处理 方法进行对比和分析, 使其达到较好效果。研究中利用几种遥感图像, 如比值增强、密度分割, 对隐伏的含铁变质岩系构造和铁矿层的显示获得了好效果。比值增强图像上的色调异常显示为: 基岩区的含铁变质岩系呈深褐色、紫色条带, 第四系分布区呈不规则点状或彩色条带显示。色调 的深浅显示含铁变质岩系埋藏的深浅。通过图像增强处理, 圈定了一些远景区。     

应用陆地卫星图象处理资料研究京北地区地质构造特征

中国京北地区是半复盖的中山区,植被茂盛,地势陡峻,基岩露头出露较差仅占30—40％,常规地质工作比较困难。多年来虽作了大量地质工作,获得不少成果,但该区地质构造及其与成矿规律的研究仍显不足。 京北地区是中国震旦系广布的地区,主要由碎屑岩,碳酸盐岩和火山岩建造组成,在     

Induction, adaptation and recovery of lysosomal integrity in green-lipped mussel Perna viridis

Biomarkers are generally applied to detect pollution in environmental monitoring. Such biological responses should accurately reflect the stress over time in a quantitative manner. As such, the initial and maximum responses induced by stress, as well as adaptation and recovery of these biomarkers, need to be fully understood or else erroneous false-negative or false-positive may be arrived. However, most of the biomarker studies only provided information on initially induced responses under different concentrations of toxicants, while biological adaptation and recovery were poorly known. In this study, the time required for induction, adaptation and recovery of lysosomal integrity in green-lipped mussel Perna viridis upon exposure to benzo[a]pyrene was investigated over a period of 62 days. Maximum induction occurred on day 6 when lysosomal integrity was significantly reduced by 51%, and no further change or adaptation was detected thereafter. When mussels were depurated in clean seawater after 18 days of exposure to benzo[a]pyrene, a gradual recovery was observed, with lysosomal integrity returning to its background level and showing a complete recovery after 20 days of depuration. Lysosomal integrity was significantly correlated with the body burden concentrations of benzo[a]pyrene and condition index of the mussels. The relatively fast induction (6 days) and recovery (20 days) without apparent adaptation suggested that lysosomal integrity in P. viridis can serve as a good biomarker in biomonitoring, as its response is not likely to generate both false-negative and false-positive results.     

Influences of ammonia-nitrogen and dissolved oxygen on lysosomal integrity in green-lipped mussel Perna viridis: laboratory evaluation and field validation in Victoria Harbour, Hong Kong

Lysosomal integrity in mussels has been applied as a biomarker to detect the pollution of trace organics and metals in the natural environments. However, few studies have examined the effects of water quality on the response of lysosomal integrity, in particular total ammonia-nitrogen (TAN) and dissolved oxygen (DO). This study demonstrated that high level of TAN (2.0 mg/l) and low DO (2.5 mg O₂/l) could significantly reduce the lysosomal integrity in green-lipped mussel Perna viridis, respectively by 33% and 38%, whereas the mussel lysosomal integrity decreased by 70% in the combined treatment of TAN and low DO under laboratory conditions after one week. The mussel lysosomal integrity of all treatment groups could return to the control level after a three week recovery period. In the field validation in Victoria Harbour, Hong Kong during an one-year study period, lysosomal integrity in P. viridis identified the cleanest site east to the harbour, where the lowest TAN and highest DO concentrations were found. While lysosomal integrity in mussels seemed not affected by seasonal changes, approximately 40% of the variation of this biomarker could be attributable to the changes in TAN and DO in seawater. In conclusion, the response of the mussel lysosomal integrity can be confounded by both TAN and DO prevailing in the natural environments and thus caution must be exercised in relating the observed changes in lysosomal integrity to any specific pollutant in coastal water quality monitoring studies.     

Application of NMR-based techniques in aquatic toxicology: brief examples

Nuclear magnetic resonance spectroscopy (NMR) has been employed over many years for the elucidation of chemical structures. However, in more recent years it has been used to characterize sublethal actions of pollutants in aquatic organisms. For instance, in vivo NMR involves live, intact organisms or cell cultures and the application of chemical stressors to reveal toxic mechanisms in real time. Alternatively, NMR-based metabolomics involves rapid cessation of metabolic activity following chemical exposure (via liquid N(2)) to provide an assessment of metabolic actions via more traditional NMR analysis. Two examples are briefly presented to exemplify the power of NMR for assessing toxic actions in marine and freshwater organisms.     

Stable isotopes as a useful tool for revealing the environmental fate and trophic effect of open-sea-cage fish farm wastes on marine benthic organisms with different feeding guilds

Environmental fate of fish farm wastes (FFW) released from an open-sea-cage farm at Kat O, Hong Kong was examined by measuring carbon and nitrogen stable isotope (SI) ratios in selected benthic organisms collected along a 2000 m transect from the farm. Our results showed that FFW significantly influenced the energy utilization profile of consumers near the fish farm. Although nitrogen enrichment effect on δ15N was anticipated in biota near the farm, the predicted patterns did not consistently occur in all feeding guilds. Two species of suspension-feeders, which relied on naturally δ15N-depleted sources, were δ15N-enriched near the fish farm. In contrast, both species of benthic grazer and deposit-feeder, which relied on naturally δ15N-enriched algal sources, were δ15N-depleted under the influence of FFW. The SI signatures of biota can, therefore, serve as feasible biomarkers for FFW discharges only when the trophic structure of the receiving environment is fully elucidated.     

Influence of a Brazilian sewage outfall on the toxicity and contamination of adjacent sediments

The submarine sewage outfall of Santos (SSOS) is situated in the Santos Bay (São Paulo, Brazil) and is potentially a significant source of contaminants to the adjacent marine ecosystem. The present study aimed to assess the influence of SSOS on the sediment toxicity and contamination at Santos Bay. At the disposal site, sediments tended to be finer, organically richer and exhibited higher levels of surfactants and metals, sometimes exceeding the “Threshold Effect Level” values. The SSOS influence was more evident toward the East, where the sediments exhibited higher levels of TOC, total S and metals during the summer 2000 sampling campaign. Sediment toxicity to amphipods was consistently detected in four of the five stations studied. Amphipod survival tended to correlate negatively to Hg, total N and % mud. This work provides evidence that the SSOS discharge affects the quality of sediments from Santos Bay, and that control procedures are warranted.