Effects of the parasiticide ivermectin on the cladoceran Daphnia magna and the green alga Pseudokirchneriella subcapitata

Although widely used for the treatment of endo- and ectoparasites in livestock and pets, very few data on chronic effects on aquatic organisms are available for the parasiticide ivermectin. In the present study, toxicity of ivermectin to two freshwater organisms, the cladoceran Daphnia magna and the green alga Pseudokirchneriella subcapitata was investigated. For D. magna, a mean LC(50) 48 h of 5.7 ngl(-1) was derived from 10 acute tests. Chronic toxicity of ivermectin to D. magna was extremely high: with 0.001 and 0.0003 ngl(-1), respectively, nominal LOEC and NOEC based on growth and reproduction were far below the analytical limit of detection for this compound. P. subcapitata was considerably less sensitive to ivermectin than D. magna. For both growth rate and yield, EC(50) was >4,000 microgl(-1), LOEC was 1,250 microgl(-1) and NOEC 391microgl(-1). In view of the high toxicity to D. magna, the use of ivermectin might pose a risk to local aquatic ecosystems. Further studies should be carried out to investigate the effects of ivermectin and its degradation products on pelagic and benthic freshwater invertebrates.     

Fenitrothion, an organophosphate, affects running endurance but not aerobic capacity in fat-tailed dunnarts (Sminthopsis crassicaudata)

We measured aerobic metabolism during cold exposure and exercise performance (run duration and oxygen consumption while running at 1 m s(-1)) in the fat-tailed dunnart Sminthopsis crassicaudata, a dasyurid marsupial, before and after ingestion of 30 mg kg(-1) of fenitrothion, an organophosphate (OP) pesticide. Running endurance of OP-exposed animals was less than half that of control animals over the first 3 days after dosing and 55% of control animal endurance on day 5 post-dose. Despite these declines, peak metabolic rate at this running speed (9.3 times basal metabolic rate; BMR) was unaffected by OP exposure. Peak metabolic rate (PMR) and cumulative oxygen consumption during a 1-h exposure to conditions equivalent to -20 degrees C did not differ between OP-treated and control dunnarts, with PMR averaging 11 times BMR. We conclude that fenitrothion-induced exercise fatigue is not due to limitations in oxygen or substrate delivery to muscle or in their uptake per se, but more likely relates to decreased ability to sustain high-frequency neuromuscular function. The persistence of locomotor impairment following OP exposure in otherwise asymptomatic animals emphasizes the importance of using performance-based measures when characterising sublethal effects of pesticide exposure in an ecological context.     

Quantitative PCR analysis of molds in the dust from homes of asthmatic children in North Carolina

The vacuum bag (VB) dust from the homes of 19 asthmatic children in North Carolina (NC) was analyzed by mold specific quantitative PCR. These results were compared to the analysis of the VB dust from 176 homes in the HUD, American Healthy Home Survey of homes in the US. The Environmental Relative Moldiness Index (ERMI) was calculated for each of the homes. The mean and standard deviation (SD) of the ERMI values in the homes of the NC asthmatic children was 16.4 (6.77), compared to the HUD survey VB ERMI value mean and SD of 11.2 (6.72), and was significantly greater (t-test, p = 0.003) in the NC asthmatic children's homes. The molds Chaetomium globosum, Aspergillus fumigatus, and the Eurotium Group were the primary species in the NC homes of asthmatics, making the ERMI values significantly higher (p < 0.02 for each). Vacuum bag dust analysis may be a useful method for estimating the mold burden in a home.     

Risk assessment of aquifer storage transfer and recovery with urban stormwater for producing water of a potable quality

The objective of the Parafield Aquifer Storage Transfer and Recovery research project in South Australia is to determine whether stormwater from an urban catchment that is treated in a constructed wetland and stored in an initially brackish aquifer before recovery can meet potable water standards. The water produced by the stormwater harvesting system, which included a constructed wetland, was found to be near potable quality. Parameters exceeding the drinking water guidelines before recharge included small numbers of fecal indicator bacteria and elevated iron concentrations and associated color. This is the first reported study of a managed aquifer recharge (MAR) scheme to be assessed following the Australian guidelines for MAR. A comprehensive staged approach to assess the risks to human health and the environment of this project has been undertaken, with 12 hazards being assessed. A quantitative microbial risk assessment undertaken on the water recovered from the aquifer indicated that the residual risks posed by the pathogenic hazards were acceptable if further supplementary treatment was included. Residual risks from organic chemicals were also assessed to be low based on an intensive monitoring program. Elevated iron concentrations in the recovered water exceeded the potable water guidelines. Iron concentrations increased after underground storage but would be acceptable after postrecovery aeration treatment. Arsenic concentrations in the recovered water continuously met the guideline concentrations acceptable for potable water supplies. However, the elevated concentration of arsenic in native groundwater and its presence in aquifer minerals suggest that the continuing acceptable residual risk from arsenic requires further evaluation.     

Evaluation of Short-to-Medium Range Streamflow Forecasts Obtained Using an Enhanced Version of SRM1

Harshburger, Brian J., Karen S. Humes, Von P. Walden, Brandon C. Moore, Troy R. Blandford, and Albert Rango, 2010. Evaluation of Short-to-Medium Range Streamflow Forecasts Obtained Using an Enhanced Version of SRM. Journal of the American Water Resources Association (JAWRA) 46(3):603-617. DOI: 10.1111/j.1752-1688.2010.00437.x Abstract: As demand for water continues to escalate in the western United States, so does the need for accurate streamflow forecasts. Here, we describe a methodology for generating short-to-medium range (1 to 15 days) streamflow forecasts using an enhanced version of the Snowmelt Runoff Model (SRM), snow-covered area data derived from MODIS products, data from Snow Telemetry stations, and meteorological forecasts. The methodology was tested on three mid-elevation, snowmelt-dominated basins ranging in size from 1,600 to 3,500 km². To optimize the model performance and aid in its operational implementation, two enhancements have been made to SRM: (1) the use of an antecedent temperature index method to track snowpack cold content, and (2) the use of both maximum and minimum critical temperatures to partition precipitation into rain, snow, or a mixture of rain and snow. The comparison of retrospective model simulations with observed streamflow shows that the enhancements significantly improve the model performance. Streamflow forecasts generated using the enhanced version of the model compare well with the observed streamflow for the earlier leadtimes; forecast performance diminishes with leadtime due to errors in the meteorological forecasts. The three basins modeled in this research are typical of many mid-elevation basins throughout the American West, thus there is potential for this methodology to be applied successfully to other mountainous basins.     

Field evaluation of nitrogen availability from fresh and composted manure

Prediction of manure nitrogen availability to crops is key to ensuring adequate production while minimizing potential adverse environmental impacts. This field study estimated first-year and residual N availability from several manures subjected to various levels of processing, and evaluated the applicability of the pre-sidedress soil N test (PSNT) in fields receiving the different manures using corn (Zea mays L.) as the test crop. Plots received several rates of fresh (FP), dried (DP), or composted (CP) poultry (Gallus gallus domesticus) manure, composted cow (Bos taurus) (CC) manure, ammonium nitrate (AN), or no N. Crop yields and N uptake from plots where CC was applied were undistinguishable from controls in most years, whereas poultry manures significantly increased corn production. Average apparent first-year N availability, as measured by fertilizer equivalence, was 57, 53, 14, and 4% for FP, DP, CP, and CC respectively. Apparent second-year N availability, as measured by relative effectiveness, was 18, 19, 12, and 7% for FP, DP, CP, and CC; however, for CC both first- and second-year estimates of apparent N recovery (ANR) could statistically not be separated from the controls. Apparent nitrogen avail-ability was greater for less processed manures and for CP compared to CC, emphasizing that producers should know the source and level of compost stability when these materials are used as a primary nutrient source. The PSNT successfully (87% correct) identified sites with a critical value of 24 mg kg(-1) that were N sufficient across a variety of N amendments from those that would have benefitted from additional N input.