Decadal changes in the Forth Estuary and firth of forth in relation to the North Sea 1980–2000
Tóm tắt
Pronounced changes have occurred in the fisheries, plankton and benthos of the North Sea The Forth Estuary and the Firth of Forth have been monitored from 1980 to 2000. River flows, circulation, salinity and sediment distributions have not changed significantly. Regulation of point source discharges has improved many other aspects of the Forth system: inputs of organic material have declined and there has been a concomitant rise in dissolved oxygen during summer in the upper Forth Estuary. The rise in dissolved oxygen has led to increasing numbers of smelt caught in the upper estuary and to increasing inputs of nitrate generated by nitrification in the turbidity maximum of the estuary during summer. In winter, conservative mixing of nutrients is seen and there has been little change in winter nutrient concentrations in the Forth Estuary and Firth of Forth. Trace metal and trace organic inputs have been reduced so that aqueous concentrations have fallen rapidly. Body burdens of trace contaminants in biota have been slower to fall. Throughout the higher trophic levels of the Forth, fluctuating and patchy distributions of chlorophyll and phytoplankton have obscured any long term trends.
Tài liệu tham khảo
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