human activities in the fields of agriculture, municipal and industry introduce significant amounts of nutrients and organic materials into the rivers and streams resulting in their contamination. computer models such as qual2kw are used extensively for water quality management of rivers and streams. the qual2kw model is a one dimensional, non-uniform, steady water quality model, which has been...

Nitrogen isotope values from coral tissue collected over depth-light gradients are reported from Jamaica and Zanzibar. The Jamaica suite consists of multiple specimens of three coral species (Montustrea annularis, Porites astreoides, and Agaricia agaricites) sampled at increasing depths. For each species, combined tissue/zooxanthellae 615N decreases significantly with decreasing availability of...

Wetland ecosystems are represented as a significant reservoir of organic carbon and play an important role in mitigating the greenhouse effect. In order to compare the compositions and distribution of organic carbon in constructed and natural river wetlands, sediments from the Xinxue River Constructed Wetland and the Xinxue River, China, were sampled at two depths (0-15 cm and 15-25 cm) in both...

A dynamic and mechanistic mass balance model (Integrated Aquaculture/Agriculture System model, or IAAS) for predicting nitrogen and organic matter outputs from aquaculture ponds and their subsequent recycling in conventional agriculture practices has been developed and calibrated using data from Honduras, Thailand and Malawi. The model, developed using Stella modeling software (High Performanc...

Tailwater recovery systems (TWR) provide an excellent testbed for examining nutrient loading from agriculture non-point sources, such as pre-harvest rice (Oryza sativa L.) field drains, on receiving waters. In this study, the focus was to use continuous sampling of nitrate-nitrogen (NO3−-N) concentration, paired with discrete grab samples of water which were analyzed for total nitrogen and inor...

Although organic nitrogen (ON) has been found to be a ubiquitous and significant component in wet and dry deposition, almost nothing is known about its concentration or composition in fog waters. To address this gap, we have investigated the concentration and composition of ON in fog waters collected in Davis, in California’s Central Valley. Significant quantities of dissolved organic nitrogen ...