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The dissipation routes of chlorpyrifos spiked in an Udic Ferrisol at the dosage of 400 ngg-1, which represents a residual level after an agricultural application, were studied in a laboratory, using the natural soil under three moisture regimes, sterilised, and organic matter-free soils in the dark at 20°C. The obtained results showed that higher soil moisture caused faster dissipation, and the abiotic and biotic contributions to the total dissipated amount of the applied chlorpyrifos in the soil accounted for 77.3-85.2% and 14.7-- 22.7%, respectively. In the sterilised soil, the contribution of organic matter to chlorpyrifos dissipation was noticed to account for 95% in the earlier two weeks, and was nearly equal to that of soil minerals two weeks after the incubation. [ABSTRACT FROM AUTHOR]

N-Nitrosodimethylamine (NDMA), a potential carcinogen, may contaminate the groundwater when the reclaimed wastewater is used for irrigation and groundwater recharge. Henry's law constant is a critical parameter to assess the fate and transport of reclaimed wastewater-borne NDMA in the soil profile. We conducted a laboratory experiment in which the change of NDMA concentration in water exposed to the atmosphere was measured with respect to time and, based on the data, obtained the dimensionless Henry's law constant (KH') of NDMA, at 1.0 × 10-4. The KH' suggests that NDMA has a relatively high potential to volatilize in the field where NDMA-containing wastewater is used for irrigation and the volatilization loss may be a significant pathway of NDMA transport. The experiment was based on the two boundary-layer approach of mass transfer at the atmosphere-water interface. It is an expedient method to delineate KH' for volatile or semi-volatile compounds present in water at low concentrations. [ABSTRACT FROM AUTHOR]

A procedure for estimating Greenhouse gas (GHG) emissions from a wastewater reclamation plant in Beijing was developed based on the process chain model. GHG emissions under two typical water reclamation treatment processes, the coagulation-sedimentation-filtration traditional process and advanced biological treatment process, were examined. The total on-site GHG emissions were estimated to be 0.0056 kg/m³ and 0.6765 kg/m³ respectively, while total off-site GHG emissions were estimated to be 0.3699 kg/m³ and 0.4816 kg/m³. The overall GHG emissions were 0.3755 kg/m³ under the type 1 treatment, which is much lower than that under the type 2 of 1.1581 kg/m³. Emissions from both processes were lower than that from the tap water production. Wastewater reclamation and reuse should be promoted as it not only saves the water resources but also can reduce the GHG emissions. Energy consumption was the most significant source of GHG emissions. Biogas recovery should be employed as it can significantly reduce the GHG emissions, especially under the type 2 treatment process. Considering the wastewater treatment and reclamation process as a whole, the type 2 treatment process has advantages in reducing the GHG emissions per unit of pollutant. This paper provides scientific basis for decision making. [ABSTRACT FROM AUTHOR]

Describes a kilowatt radio frequency discharge excited diffusively cooled slab waveguide carbon monoxide laser. Cooling of the top and bottom electrodes with liquid nitrogen; Maximum laser power output obtained using the design.

A case study of the cancer risk to humans posed by persistent organic pollutants (POPs) in an industrial area of China, which has a long history of contamination from many sources, is presented. Relatively great concentrations of POPs around the chemical industrial parks have the potential to be chronically carcinogenic to local people. Sixteen individual PAHs listed for priory control by the U.S. Environmental Protection Agency (USEPA), metabolites of DDTs, and isomers of HCHs were measured in soils and a human health risk assessment was conducted by use of USEPA exposure models for children and adults, respectively. Geostatistical methods were used to simulate the spatial diffusion of potential carcinogenic risk, and non-parametric Mann-Whitney U and Kruskal-Wallis tests were employed to analyze the impact of point sources on the surrounding area. The mean value of the sum of Excess Lifetime Cancer Risk (∑ELCR) exceeded the generally acceptable risk level of 1.0E-06 recommended by the USEPA for carcinogenic chemicals. The maximum ∑ELCR was 2.9E-04 for children, which was observed inside the chemical industrial parks. Contamination at the chemical industrial parks caused significant spatial diffusion of ELCR values caused by PAHs, DDT, and HCH. [ABSTRACT FROM AUTHOR]

Distributions of arsenic and metals in surface sediments collected from the coastal and estuarine areas of the northern Bohai and Yellow Seas, China, were investigated. An ecological risk assessment of arsenic and metals in the sediments was evaluated by three approaches: the Sediment Quality Guidelines (SQGs) of the United States Environmental Protection Agency (USEPA), the degree of contamination, and two sets of SQGs indices. Sediments from the estuaries of the Wuli and Yalu Rivers contained some of the greatest concentrations of arsenic, cadmium, copper, mercury, lead, and zinc. Median concentrations of cadmium and mean concentrations of lead and zinc were greater than background concentrations determined for the areas. All sediments were considered to be heavily polluted by arsenic, but moderately polluted by chromium, lead, and cadmium. Current concentrations of arsenic and metals are unlikely to be acutely toxic, but chronic exposures would be expected to cause adverse effects on benthic invertebrates at 31.4% of the sites. [ABSTRACT FROM AUTHOR]