To elucidate the fate of river-borne nitrate in the estuarine environment, we measured nitrate concentrations and d15N and d18O of nitrate along the salinity gradient in the estuary of the river Elbe, one of the largest German rivers discharging into the North Sea. Nitrate concentrations in river waters ranged from 78 mmol L21 to 232 mmol L21; d15N varied from 8.2% to 16.2%, and the d18O values...

Field observations and model simulations are presented of the tidal flow over a scour hole at the mouth of the Dyfi Estuary, mid-Wales, U.K. This scour hole is maintained by locally high flow speeds resulting from convergence, and then divergence, of the flow over the hole. Fixed features of the local bathymetry may also have served to stabilise its location (over decades). Model simulations of...

The objectives of this study were to examine surface sediments in the San Francisco Estuary for PAH composition over a range of spatial and temporal scales to determine distributions, trends, and possible sources. Surface sediments (top 5 cm) were collected at 26 sites from 1993 to 2001. The mean total PAH (SPAH) concentration in sediments was spatially distributed as Central Bay (230 mg/kg TOC...

Here we report multiple parameters used to describe the diagenetic state of sediments, including total hydrolysable amino acid (THAA), amino acid enantiomer, chlorin (CI) and amino acid degradation (DI, RI) indices, along a transect between the Upper St. Lawrence Estuary and the Gulf of St. Lawrence, Canada. The study area is characterized by gradients in water oxygen concentration, water depth...

High rainfall associated with El Niño events significantly increases runoff and stream discharge in southern Brazil. High freshwater discharge changes salinity, temperature, and water circulation patterns that can affect the fish estuarine assemblage. Using long-term data obtained from standardized surveys, we analyzed fish assemblage structure and dynamics in shallow waters of the Patos Lagoon...

Factors influencing the migration and swimming depth of Atlantic salmon kelts Salmo salar L. within the York Estuary and Gaspé Bay (Québec, Canada), and in the Gulf of St. Lawrence between Gaspé Bay and the Strait of Belle Isle (Newfoundland, Canada) were studied using acoustic telemetry. In 2006 and 2007, a total of 49 kelts were tagged with acoustic transmitters equipped with depth sensors, r...

BACKGROUND Deforestation is one of the most ubiquitous forms of land degradation worldwide. Although remote sensing and aerial photographs can supply valuable information on land/use cover changes, they may not regularly be available for some tropical coasts (e.g., Cameroon estuary) where cloud cover is frequent. With respect to mangroves, researchers are now employing local knowledge as an alt...

Estuarine hydrodynamics is a key factor in the definition of the filtering capacity of an estuary and results from the interaction of the processes that control the inlet morphodynamics and those that are acting in the mixing of the water in the estuary. The hydrodynamics and suspended sediment transport in the Camboriú estuary were assessed by two field campaigns conducted in 1998 that covered...

Nonylphenol is an endocrine disruptor with harmful effects including feminization and carcinogenesis on various organisms. This study aims to investigate the distribution and ecological risks of nonylphenol in the Daliao River Estuary, China. Nonylphenol, together with other phenolic endocrine disruptors (bisphenol A, 4-t-butylphenol, 4-t-octylphenol, and 2,4-dichlorophenol), was detected in su...

Over the last 20 years, loss of seagrass beds, often related with increased eutrophication, became a common problem worldwide. In the Mondego estuary (Portugal), eutrophication has triggered serious biological changes, which led to an overall increase in primary production and to a progressive replacement of seagrass Zostera noltii beds by coarser sediments and opportunistic macroalgae. The eff...