Does urban development explain river water quality better than proximity to freshwater and the sea?

Details

This research aimed to identify how land use and subsequent pulse-driven events affect water quality across an urbanization gradient in three blackwater rivers in northeast Florida that contribute to a common estuary ecosystem.

In this observational field monitoring study, three blackwater rivers in St. Augustine, Florida, were classified as rural, suburban, and urban based on the percentages of residential, industrial, and commercial parcels. Turbidity, dissolved oxygen, fluorescent dissolved organic matter, chlorophyll a, salinity, and pH were measured at 15-minute intervals from May to December 2020. Monthly concentrations of phosphate, nitrate, ammonium, total coliforms, and E. coli were also examined.

Principal component analyses identified distance to the freshwater source, distance to the inlet, salinity, dissolved oxygen, and pH as major sources of variation between sites. The researchers concluded that significant physicochemical differences between sites were more likely due to proximity to an inlet or freshwater source than to the percentage of urban parcels. They emphasized that monitoring sites’ distances from freshwater and saltwater influences should be considered because these influences affect water quality in estuarine systems.

The study provides insight into potential water quality responses to urbanization—or the absence of such responses—and addresses the challenges of choosing optimal locations for long-term, in situ water quality monitoring studies of urbanization in blackwater rivers.