Spatial variability of soil phosphorus in relation to the topographic index and critical source areas: sampling for assessing risk to water quality

A measure of soil P status in agricultural soils is generally required for assisting with prediction of potential P loss from agricultural catchments and assessing risk for water quality. The objectives of this paper are twofold: (i) investigating the soil P status, distribution, and variability, both spatially and with soil depth, of two different first-order catchments; and (ii) determining variation in soil P concentration in relation to catchment topography (quantified as the "topographic index") and critical source areas (CSAs). The soil P measurements showed large spatial variability, not only between fields and land uses, but also within individual fields and in part was thought to be strongly influenced by areas where cattle tended to congregate and areas where manure was most commonly spread. Topographic index alone was not related to the distribution of soil P, and does not seem to provide an adequate indicator for CSAs in the study catchments. However, CSAs may be used in conjunction with soil P data for help in determining a more "effective" catchment soil P status. The difficulties in defining CSAs a priori, particularly for modeling and prediction purposes, however, suggest that other more "integrated" measures of catchment soil P status, such as baseflow P concentrations or streambed sediment P concentrations, might be more useful. Since observed soil P distribution is variable and is also difficult to relate to nationally available soil P data, any assessment of soil P status for determining risk of P loss is uncertain and problematic, given other catchment physicochemical characteristics and the sampling strategy employed.     

Case study: Management system verification using responsible care® at Rohm & Haas: Lessons learned

In this article, Rohm & Haas' Responsible Care® implementation strategy and management system verification (MSV) experiences are detailed. Recommendations on how to strengthen the verification process are provided.     

Associations between grab sample and integrated radon measurements in dwellings in Maine and Texas

Radon concentrations were measured in several locations in each of approximately 100 dwellings in central Maine and in Houston, TX. Integrated samples were taken during the heating (or cooling) seasons with commercially available passive alpha track devices, while grab samples were taken at the time of integrated sampler deployment. It was found that both indoor and outdoor measurements in both areas were distributed log normally, and that the geometric mean of indoor measurements in Maine was three times higher than that of corresponding measurements in the Houston area. It was also noted that the mean of the indoor grab sample measurements was not significantly different from the mean of the indoor integrated measurements, and that the degree of correlation between the grab samples and a given indoor integrated sample was nearly as good as between integrated samples taken at different living area locations.     

Reaction mechanism of arsenic capture by a calcium-based sorbent during the combustion of arsenic-contaminated biomass: A pilot-scale experience

Pilot-scale combustion is required to treat arsenic-enriched biomass in China. CaO addition to arsenic-enriched biomass reduces arsenic emission. CaO captures arsenic via chemical adsorption to form Ca₃(AsO₄)₂. Large quantities of contaminated biomass due to phytoremediation were disposed through combustion in low-income rural regions of China. This process provided a solution to reduce waste volume and disposal cost. Pilot-scale combustion trials were conducted for in site disposal at phytoremediation sites. The reaction mechanism of arsenic capture during pilot-scale combustion should be determined to control the arsenic emission in flue gas. This study investigated three Pteris vittata L. biomass with a disposal capacity of 600 kg/d and different arsenic concentrations from three sites in China. The arsenic concentration in flue gas was greater than that of the national standard in the trial with no emission control, and the arsenic concentration in biomass was 486 mg/kg. CaO addition notably reduced arsenic emission in flue gas, and absorption was efficient when CaO was mixed with biomass at 10% of the total weight. For the trial with 10% CaO addition, arsenic recovery from ash reached 76%, which is an ~8-fold increase compared with the control. Synchrotron radiation analysis confirmed that calcium arsenate is the dominant reaction product.     

Thermal modeling,characterization, and enviro-economic investigations on inclined felt sheet solar distiller for seawater desalination

Environmental Science and Pollution Research - Sustainable desalination can be achieved by adopting renewable energy-based low-cost and low-impact desalting techniques. In this investigation,...     

Male choice and sperm competition as constraints on polyandry in the red-necked phalarope Phalaropus lobatus

Summary The mating system of the red-necked phalarope Phalaropus lobatus is usually classed as polyandrous, but studies show that the majority of females are monogamous. Polyandry appears to be constrained because later arriving males do not usually nest with females that have already laid a clutch that season (C1-females), despite the sexual receptiveness of these females. Rather they nest with females that have not previously laid a clutch that season (C0-females). Five potential explanations of this constraint on polyandry were tested. Two hypotheses, invoking female-female competition, were not supported as female agonistic success appeared to be unrelated to priority of access to males, and there was no apparent difference between C0- and C1-females in their ability to find unpaired males. Two hypotheses suggest that C0-females are preferred by males either because they can initiate a clutch more rapidly or because they lay larger eggs. Neither hypothesis was supported by the available data. The data upheld a third male choice hypothesis that C1-females are discriminated against because they have copulated previously with another male and this may compromise paternity. Secondary males copulated and attempted to copulate more often when paired with C1-females, suggesting that sperm competition was greater and confidence of paternity was lower. Corroborative evidence of active male choice showed that males were more aggressive towards associating C1-females than towards C0-females, although how males discriminated between the two classes of females was not determined.