The effects of riverine discharge on temperature, salinity, suspended sediment and chlorophyll a in a Mississippi delta estuary measured using a flow-through system

Abstract The impact of diverted Mississippi River water on temperature, salinity, total suspended sediment (TSS) and chlorophyll a were monitored in the Breton Sound estuary from September 7, 2000, to August 28, 2002. Twenty-seven transects were carried out using a flow-through system to continuously measure temperature, salinity, turbidity and fluorescence, and discrete water samples were taken at 16 locations for calibration. Discharge from the river diversion structure ranged from 0 to 213 m 3 /s, with several large pulses of water released during the spring of 2001 and 2002. There was a strong seasonal temperature signal in the estuary, with summer highs of >30 °C and winter lows of a concentrations were highest in mid-estuary during summer and fall low discharge, and lowest during winter and spring high discharge. Chlorophyll a levels were generally less than 10 μg/L in the upper estuary, with concentrations rising in the mid-estuary generally to 20–30 μg/L during late summer and fall, and decreasing in the lower estuary. There were several periods of less than a month with unusually high chlorophyll a concentrations, ranging from 38 to >60 μg/L, that occurred during late summer and early winter.

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