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Nutrient export from highly managed coastal watersheds: Lessons learned from long-term monitoring data
Citation:
Wan, Y. Nutrient export from highly managed coastal watersheds: Lessons learned from long-term monitoring data. Sixth Interagency Conference on Research in the Watersheds (ICRW), Shepherdstown, WV, July 23 - 26, 2018.
Impact/Purpose:
Nutrient pollution is one of the most widespread water quality problems facing the US and it has far-ranging consequences for environmental condition, economic prosperity, and human health and well-being. For example, the combined costs were approximately $2.2 billion annually as a result of eutrophication in U.S. freshwaters. This study analyzed a long-term (1979~2014) water quality and discharge data set collected from four adjacent coastal watersheds in south Florida where land and water resources are highly managed through an intricate canal network. The results indicated unique patterns of temporal and spatial changes in nutrient concentrations and export in relation to watershed hydrology and land/water resources management. The anthropogenic and hydro-climatic controls on export behavior had great implications in nutrient management programs for restoration of the downstream estuarine ecosystem.
Description:
The health of estuarine ecosystems is often influenced by hydraulic and nutrient loading from upstream watersheds. This study analyzed a long-term (1979~2014) water quality and discharge data set collected from four adjacent coastal watersheds in south Florida where land and water resources are highly managed through an intricate canal network. The objective was to determine the temporal and spatial changes in nutrient concentrations and export behavior in relation to watershed hydrology and resources management. While close associations of nutrient concentrations with land management and storm-water retention were identified across watersheds, long-term trends in nutrient concentrations were intervened by short-term highs driven by high discharges and lows associated with regional droughts. Nutrient export exhibited a chemostatic behavior for total nitrogen for all the watersheds, largely due to the biogenic nature of organic nitrogen associated with the ubiquity of organic materials in the managed canal network. Varying degrees of chemodynamic export was present for total phosphorus, reflecting complex biogeochemical responses to the legacy of long-term fertilization, low soil phosphorus sorption, and intensive stormwater management. The anthropogenic and hydro-climatic influences on nutrient concentrations and export behavior had great implications in nutrient management programs for restoration of the downstream estuarine ecosystem.