Phytoplankton, dissolved oxygen and nutrient patterns along a eutrophic river-estuary continuum: Observation and modeling.

Transport and fate of phytoplankton blooms and excessive nutrients along salinity and turbidity gradients of a river-estuary continuum could determine when and where impaired water quality occurs. However, the general spatiotemporal patterns, underlying mechanisms and their implication for water quality management are not well understood. This study reveals typical seasonal variations and longitudinal patterns of phytoplankton, dissolved oxygen (DO) and nutrients (C, N, and P) in the lower St.

Low flows and downstream decline in phytoplankton contribute to impaired water quality in the lower Minnesota River.

The underlying physical and biogeochemical mechanisms associated with low dissolved oxygen (DO) levels below 5 mg L were examined through field data analyses and water quality modeling of the lower 40 miles of the Minnesota River. Insights into flow and water quality data of nineteen years (1999-2017) at five sites demonstrate that low DO levels parallel the obvious longitudinal (upstream-to-downstream) decline in phytoplankton biomass and increase in ammonium nitrogen (NH4) and dissolved orthophosphate (PO4) in the last 22-mile river reach (i.e.

Mercury transport and fate models in aquatic systems: A review and synthesis.

Mercury contamination in aquatic systems has been an issue to the natural ecosystem and human health. Environmental models have become a valuable decision-making tool and play a significant role in mercury pollution control and management. This paper gives an overview of currently available models for simulating mercury transport and fate in aquatic systems.

Biomass production in the Lower Mississippi River Basin: Mitigating associated nutrient and sediment discharge to the Gulf of Mexico.

A watershed model was developed using the Soil and Water Assessment Tool (SWAT) that simulates nitrogen, phosphorus, and sediment loadings in the Lower Mississippi River Basin (LMRB). The LMRB SWAT model was calibrated and validated using 21 years of observed flow, sediment, and water-quality data. The baseline model results indicate that agricultural lands within the Lower Mississippi River Basin (LMRB) are the dominant sources of nitrogen and phosphorus discharging into the Gulf of Mexico.