tailieunhanh - Ecosystem Responses to Mercury Contamination: Indicators of Change - Chapter 3

Như gần đây là một thập kỷ trước, một ít ỏi của địa lý phân tán và các dữ liệu đáng tin cậy trên thủy ngân (Hg) và metyl thuỷ ngân (MeHg) trong nước và trầm tích sẽ có các cuộc thảo luận xuất quy mô lớn khó khăn Chương trình Giám sát để thụ thai hoặc thực hiện. Phương pháp thực hiện tiến bộ hơn thời kỳ Thời gian này, cũng như cải tiến đáng kể trong sự hiểu biết của chúng ta về nguồn thủy ngân khoa học chung, đi xe đạp và số phận trong môi trường,. | 3 Monitoring and Evaluating Trends in Sediment and Water Indicators David Krabbenhoft Daniel Engstrom Cynthia Gilmour Reed Harris James Hurley and Robert Mason ABSTRACT As recently as a decade ago a paucity of geographically dispersed and reliable data on mercury Hg and methylmercury MeHg in water and sediments would have made discussions of large-scale monitoring programs difficult to conceive or implement. Methodological advancements made over this time period as well as substantial improvements in our overall scientific understanding of mercury sources cycling and fate in the environment have enabled scientists land managers and regulators to consider how environmental responses to changing mercury emissions and deposition could be monitored. A program whose ultimate goal is to assess environmental responses to changes in atmospheric Hg deposition will undoubtedly rely on sediment and water indicators as critical program components. For both water and sediment a well established set of sampling protocols and analytical procedures will enable reliable data collection across a diverse set of aquatic ecosystems. Waterbased indicators of Hg and MeHg have already been useful for documenting decadal-scale changes in Hg and MeHg concentrations in the Everglades of Florida and a seepage lake in northern Wisconsin. At both sites changes in Hg deposition were also measured and linked to the environmental response. Unfortunately there are very few other long-term records of Hg and MeHg in water and or sediment thus establishing widespread baselines or current trends is presently difficult. With increasing numbers of studies and monitoring efforts that utilized the collection of water and sediment samples however a growing database on Hg and MeHg is evolving that would be useful for site selection and establishing general contamination levels for a more coherent monitoring effort. Within an aquatic ecosystem water-based indicators are expected to be the first environmental