We conducted NO3 – stable isotope tracer releases in nine streams with varied intensities and types of human impacts in the upstream watershed to measure nitrate (NO3 ) cycling dynamics. Mean ambient NO3 – concentrations of the streams ranged from 0.9 to 21,000 lg l NO3 – N. Major N-transforming processes, including uptake, nitrification, and denitrification, all increased approximately two to ...

Excessive use of animal manure on agricultural lands can impact the quality of surface and groundwater resources. A three–year study (1998–2000) was conducted on nine 0.4–ha plots and on six 2.1–m 2 lysimeters to investigate the effect of two nitrogen (N) application rates from laying hen manure and one N application rate from urea ammonium nitrate (UAN) fertilizer on surface and groundwater qu...

background: surface water and groundwater pollution with various forms of nitrogen such as ammonium and nitrate ions is one of the main environmental risks. the major objectives of this study were to evaluate the capacity of natural zeolite (clinoptilolite) to remove no3- and nh4+ from polluted water under both batch and column conditions. methods: the laboratory batch and column experiments we...

In Australia, declining water quality in the Great Barrier Reef (GBR) is a threat to its marine ecosystems and nitrate (NO3?) from sugar cane-dominated agricultural areas coastal catchments of North Queensland key pollutant concern. Woodchip bioreactors have been identified as potential low-cost remediation technology reduce NO3? runoff cane farms. This study aimed trial different designs (deni...

Biological reduction of perchlorate by autotrophic microorganisms attached to zerovalent iron (ZVI) was studied in flow-through columns. The effects of pH, flow rate, and influent perchlorate and nitrate concentrations on perchlorate reduction were investigated. Excellent perchlorate removal performance (> or = 99%) was achieved at empty bed residence times (EBRTs) ranging from 0.3 to 63 h and ...

Complexation between hexavalent neptunium and nitrate was studied in aqueous nitric acid solution using optical absorption, vibrational and X-ray absorption spectroscopies. Distributions of aqueous [NpO2](2+), [NpO2(NO3)](+) and [NpO2(NO3)2] species were obtained as a function of nitric acid concentration between 0 and 14 M. The crystal structure of [NpO2(NO3)2(H2O)2]·H2O was determined.

The transport and deposition of anthropogenic nitrogen (N) to downwind ecosystems is significant and can be a dominant source of new N to many watersheds. Bacterially mediated denitrification in lake sediments may ameliorate the effects of N loading by permanently removing such inputs. We measured denitrification in sediments collected from lakes in the Colorado Rocky Mountains (USA) receiving ...

The removal of nitrate (NO3−-N) and antibiotics in aquaculture tail water is urgent necessary. A lab-scale up-flow immobilized biofilter (I-BF) filled with polyurethane foam (PUF) carriers a microbial consortium was developed for simultaneous tetracycline (TC). denitrification TC performance the I-BF reactor investigated under different concentrations (0, 10, 50, 100 mg·L−1), carbon/nitrogen (C...