We performed a 15N-labeling study to investigate nitrogen incorporation and retention by the benthic microbial community (bacteria and benthic microalgae) and fauna in the intertidal sediment of the subtropical Australian Brunswick Estuary. The main experiment involved an in situ 15N pulse–chase experiment. After injection of 15NH z4 into the sediment, 15N was traced into bulk sediment, total h...

Phytoremediat ion techniques for the treatment of different types of wastewater have been used by several researchers. These techniques are reported to be cost effective compared to other methods. Various contaminants like total suspended solids, dissolved solids, electrical conductivity, hardness, biochemical oxygen demand, chemical oxygen demand, dissolved oxygen, nitrogen, phosphorous, heavy...

A sensitive method involving alkaline hydrolysis and HPLC analysis has been developed to detect nanomolar levels of tryptophan dissolved in freshwater. The procedure includes 1) alkaline hydrolysis with nitrogen atmosphere in Teflon-lined Pyrex tubes with 4.2 M sodium hydroxide at 110 degrees C for 16 h, in which ascorbic acid was used as an antioxidant; 2) a determination step, in which trypto...

issolved gas supersaturation (DGS) is a condition that occurs when the partial pressures of atmospheric gases in solution exceed their respective partial pressures in the atmosphere. Individual atmospheric dissolved gases (oxygen, nitrogen, and trace gases such as argon and carbon dioxide) can often be supersaturated without adverse effects on aquatic and marine organisms. When the sum of the p...

Dissolved organic nitrogen (DON) may play an important role in plant nutrition and nitrogen fluxes in forest ecosystems. In spite of the apparent importance of DON, there is a paucity of information concerning its chemical composition. However, it is exactly this chemical characterization that is required to understand the importance of DON in ecosystem processes. The primary objective of this ...

Detailed measurements of bubble composition, dissolved gas concentrations, and plume dynamics were conducted during a 9-month period at a very intense, shallow (22-m water depth) marine hydrocarbon seep in the Santa Barbara Channel, California. Methane, carbon dioxide, and heavier hydrocarbons were lost from rising seep bubbles, while nitrogen and oxygen were gained. Within the rising seawater ...

A method for estimating denitrification and nitrogen fixation simultaneously in coastal sediments was developed. An isotope-pairing technique was applied to dissolved gas measurements with a membrane inlet mass spectrometer (MIMS). The relative fluxes of three N(2) gas species ((28)N(2), (29)N(2), and (30)N(2)) were monitored during incubation experiments after the addition of (15)NO(3)(-). For...