tailieunhanh - Ecosystem Responses to Mercury Contamination: Indicators of Change - Chapter 4

Việc giám sát của thủy ngân trong lưới thức ăn thủy sản hỗ trợ việc sản xuất cá và động vật hoang dã trong vòng IS trực tiếp đến mối lo ngại về sức khỏe và rủi ro sinh thái tiếp xúc (MeHg) metyl thuỷ ngân. Chúng tôi trình bày một khuôn khổ để theo dõi nồng độ thủy ngân trong thủy sinh vật, với trọng tâm Đánh giá Responses to Những thay đổi trong trội của thủy ngân từ lắng đọng khí quyển và các nguồn khác. Trong chương này, chúng tôi (1) Xác định các thuộc tính cụ. | 4 Monitoring and Evaluating Trends in Methylmercury Accumulation in Aquatic Biota James G. Wiener . Bodaly Steven S. Brown Marc Lucotte Michael C. Newman Donald B. Porcella Robin J. Reash and Edward B. Swain ABSTRACT The monitoring of mercury in aquatic food webs supporting the production of fish and wildlife is directly relevant to concerns about health and ecological risks of methylmercury MeHg exposure. We present a framework for monitoring concentrations of mercury in aquatic biota with emphasis on assessing responses to changes in loadings of mercury from atmospheric deposition and other sources. In this chapter we 1 identify specific attributes criteria of indicators that would be useful for discerning temporal trends and spatial patterns in the concentration of mercury in aquatic biota 2 critically evaluate and rank candidate biological indicators useful for monitoring trends in mercury 3 outline approaches for sampling and analysis of recommended biological indicators 4 identify ancillary data needs and potential confounding factors that should be considered or documented to ensure the defensible interpretation of data on monitored biological indicators and 5 consider the environmental settings waterbody type and geographic location that would be most sensitive for detecting changes in atmospheric deposition of mercury. Criteria were applied to ensure that the biological indicators selected are useful relevant and sufficiently diagnostic to detect a change in mercury bioaccumulation in response to altered mercury loadings. Toxicological problems with mercury in aquatic ecosystems result from biotic exposure to MeHg a highly toxic compound that readily accumulates in exposed organisms and can biomagnify to high concentrations in organisms atop aquatic food webs. Biotic monitoring should therefore focus on assessing trends in bioaccumulation of MeHg in samples from trophic levels below fish this requires the determination of MeHg. We considered six general