Effects of molluscicide baits on field populations of house mice

Two trials were carried out to test the effects of field applications of snail baits on populations of house mice (Mus domesticus) inhabiting cereal-cropping fields during a mouse plague in South Australia. In the first trial, grain based pellets containing 2% w/w active ingredient methiocarb, were laid in trails across fields before crops were sown. The second tested the effect of whole wheat grains treated with 1% w/w methiocarb when broadcast across maturing barley crops. Treatment effects were estimated by comparison with untreated control plots. In the methiocarb-treated wheat trial, comparison was also made with 0.3% w/w strychnine-treated wheat treatments. Methiocarb baiting reduced estimated mouse numbers by 0–46%. Surviving mice did not accept the excess bait material available. In contrast, strychnine-treated wheat reduced estimated mouse numbers by 86–94%. These trials indicate that methiocarb is not likely to be a useful field rodenticide. Furthermore, the consumption of bait by mice is not likely to jeopardise snail control operations. However, methiocarb baits could cause sufficient mortality to pose a threat to rare or endangered granivorous rodents inhabiting agricultural fields.     

Heavy Mining Vehicle Controls and Skidding Accidents

This paper examines various control locations in heavy mining vehicles. Three trucks have been tested on a skid pad in both clockwise and anticlockwise directions. The skid lengths were measured after each trial. The primary focus of the study was the positioning of various controls and their relevance to various skid lengths. Some additional measures such as NASA-TLX scales were also used to make subjective evaluations. The results are presented in this paper. The findings clearly indicate the relevance of control locations to actual skid lengths. The poorly located controls resulted in greater skid lengths. This is an important finding as skid lengths are related to greater reaction times in a skidding situation and hence greater risk of accidents on relevant trucks. Such accidents can incur large repair bills for damaged equipment whereas more importantly, jeopardizing the life and safety of heavy mining vehicle drivers.     

Quantifying phosphorus levels in soils, plants, surface water, and shallow groundwater associated with bahiagrass-based pastures

Background, aim, and scope  

Recent assessments of water quality status have identified eutrophication as one of the major causes of water quality ‘impairment’ not only in the USA but also around the world. In most cases, eutrophication has accelerated by increased inputs of phosphorus due to intensification of crop and animal production systems since the early 1990s. Despite substantial measurements using both laboratory and field techniques, little is known about the spatial and temporal variability of phosphorus dynamics across landscapes, especially in agricultural landscapes with cow-calf operations. Critical to determining environmental balance and accountability is an understanding of phosphorus excreted by animals, phosphorus removal by plants, acceptable losses of phosphorus within the manure management and crop production systems into soil and waters, and export of phosphorus off-farm. Further research effort on optimizing forage-based cow-calf operations to improve pasture sustainability and protect water quality is therefore warranted. We hypothesized that properly managed cow-calf operations in subtropical agroecosystem would not be major contributors to excess loads of phosphorus in surface and ground water. To verify our hypothesis, we examined the comparative concentrations of total phosphorus among soils, forage, surface water, and groundwater beneath bahiagrass-based pastures with cow-calf operations in central Florida, USA.     

Denitrification from a swine lagoon overland flow treatment system at a pasture-riparian zone interface

In manure disposal systems, denitrification is a major pathway for N loss and to reduce N transport to surface and ground water. We measured denitrification and the changes in soil N pools in a liquid manure disposal system at the interface of a pasture and a riparian forest. Liquid swine manure was applied weekly at two rates (approximately 800 and 1600 kg N ha-1 yr-1) to triplicate plots of overland flow treatment systems with three different vegetation treatments. Denitrification (acetylene block technique on intact cores) and soil N pools were determined bimonthly for 3 yr. The higher rate of manure application had higher denitrification rates and higher soil nitrate. Depth 1 soil (0-6 cm) had higher denitrification, nitrate, and ammonium than depth 2 soil (6-12 cm). The vegetation treatment consisting of 20 m of grass and 10 m of forest had lower denitrification. Denitrification did not vary significantly with position in the plot (7, 14, 21, and 28 m downslope), but nitrate decreased in the downslope direction while ammonium increased downslope. Denitrification ranged from 4 to 12% of total N applied in the manure. Denitrification rates were similar to those from a nearby dairy manure irrigation site, but were generally a lower percent of N applied, especially at the high swine effluent rate. Denitrification rates for these soils range from 40 to 200 kg N ha-1 yr-1 for the top 12 cm of soil treated with typical liquid manure that is high in ammonium and low in nitrate.     

Concentrations and loadings of polybrominated diphenyl ethers in dust from low-income households in California

California residents may experience the highest polybrominated diphenyl ether (PBDE) flame retardant exposures in the United States, the nation with the highest body burdens worldwide. It is hypothesized that Californians' high exposures are due to the state's strict furniture flammability standards. Ingestion of PBDE-contaminated dust, to which children may be particularly susceptible, is a dominant exposure pathway. Low-income populations may also face disparately high exposures due to the presence of older, deteriorated or poorly manufactured furniture treated with PBDEs. We collected up to two dust samples per home (54 samples total), several days apart, from low-income California households in the urban community of Oakland (n=13 homes) and the agricultural community of Salinas (n=15 homes). We measured BDE-47, BDE-99 and BDE-100, the major constituents of the penta-PBDE flame retardant formulation commonly used in furniture. All three PBDE congeners were detected in every sample with concentrations (loadings) ranging from 185 to 126,000ng/g (621-264,000ng/m(2)), 367-220,000ng/g (1550-457,000ng/m(2)), and 84-41,100ng/g (257-85,700ng/m(2)) for BDE-47, BDE-99 and BDE-100, respectively. Median concentrations (loadings) observed in Salinas homes for BDE-47, BDE-99 and BDE-100 were 3100ng/g (10,800ng/m(2)), 5480ng/g (19,500ng/m(2)), and 1060ng/g (3810ng/m(2)), respectively, and in Oakland homes 2780ng/g (10,700ng/m(2)), 4450ng/g (19,100ng/m(2)), and 1050ng/g (4000ng/m(2)), respectively. Maximum concentrations for BDE-47 and BDE-99 are the highest reported to date. Indoor concentrations and loadings did not significantly differ between communities; concentrations and loadings were strongly correlated between collections for all three congeners (Spearman rho=0.79-0.97, p<0.002). We estimated non-dietary ingestion of each congener for one child in each home (n=28 children) and found that estimated intake for BDE-47 and BDE-99 exceeded the U.S. Environmental Protection Agency's recommended chronic reference dose for three and five children, respectively. Children's estimated intake via dust ranged from 1.0 to 599ng/kg/day, 2.0-1065ng/kg/day and 0.5-196ng/kg/day for BDE-47, BDE-99 and BDE-100, respectively. In order to mitigate these exposures, future research must address the factors that contribute to PBDE exposures in low-income homes.     

Methyl bromide as a building disinfectant: interaction with indoor materials and resulting byproduct formation

Several buildings were contaminated with Bacillus anthracis in the fall of 2001. These events required consideration of how to disinfect large indoor spaces for continued worker occupation. The interactions of gaseous disinfectants with indoor materials may inhibit the disinfection process, cause persistence of the disinfectant, and lead to possible byproduct formation and persistence. Methyl bromide (CH3Br) is a candidate for disinfection/deactivation of biological agents in buildings. In this study, 24 indoor materials were exposed to CH3Br for 16 hr at concentrations ranging from 100 to 2500 ppm in 48-L electropolished stainless steel chambers. CH3Br concentrations were measured during and after disinfection. Its interactions with materials were observed to be small, with nearly complete and rapid desorption. Between 3% and 8% of CH3Br adsorbed to four materials (office partition, ceiling tile, particle-board, and gypsum wallboard with satin paint), and the degree of adsorption decreased with increasing relative humidity. The percentage of adsorption to all other materials was <2%. This result suggests that when designing disinfection events with CH3Br, loss to indoor materials can be neglected in terms of disinfectant dose calculations. Possible reaction products were identified and/or quantified before and after exposure to CH3Br. Several monomethylated and dimethylated aliphatic compounds were observed in chamber air at low concentrations after the exposures of six materials to CH3Br. Concentration increases also occurred for chemicals that were observed to naturally off-gas from materials before exposure to CH3Br, suggesting that CH3Br may play a role in enhancing the natural off-gassing of chemicals, for example, by competitive displacement of compounds that already existed in the materials. The results described in this paper should facilitate the design of building disinfection systems involving CH3Br.