This paper hypothesizes that arsenic in drinking water indirectly contributes to Buruli ulcer (BU), a skin disease caused by Mycobacterium ulcerans (MU) infection. Samples of groundwater and surface water used as drinking water by the population in Ghana's Amansie West district (part of which has a high prevalence of BU), were collected near rural settlements and analysed for arsenic. Arsenic concentration levels per settlement were compared with BU prevalence. A positive exposure-response relationship was obtained between arsenic in surface water and BU (r2 = 0.82). However, there is no significant exposure-response relation between groundwater and BU.

Members from all four Weed Science Society of America (WSSA) regions in the United States ranked the research need to “develop new methods for controlling the movement of herbicides and their metabolites into ground water, surface water, and air” first of six major weed science research needs. Canadian members ranked the need to “devise more efficient and less costly weed control technology for conservation-tillage crop-production systems” first; but they also gave high ratings to “improve base knowledge of weed science, improve applicator training, and transfer of information to Extension Service personnel, farm producers, and administrators” and to “discover new ecological, biological, and non-chemical methods of weed control.” The needs to “develop improved methods of increasing the tolerance of crops to herbicides” and to “develop new technology for control of perennial weeds of crops and rangeland” were ranked low. The WSSA Research Committee, at the request of WSSA Presidents J. D. Riggleman (1985) and O. C. Burnside (1986), asked 977 members to rank weed science research needs. The members (ca 50% of the active membership in North America) were selected at random from every other state, federal, industry, and “other” member of each state or province from the up-to-date list of the WSSA business office. Within the highest ranked priority research need, the 422 U.S. and Canadian respondents consistently ranked the research areas (a) to “develop new application techniques that minimize or eliminate herbicides and their residues in air and water”, and (b) to “conduct research to regulate movement of herbicides through the soil profile to avoid contamination of ground water” high, regardless of the type of employment. They emphasized increasing research on the morningglory (Ipomoea spp. # IPOXX) complex, yellow nutsedge (Cyperus esculentus L. # CYPES), quackgrass [Agropyron repens (L.) Beauv. # AGREE], and several other weeds. More members, regardless of region or type of employment, ranked conservation tillage the most important crop or situation that needed new and improved weed control technology.

Metolachlor and metribuzin loss in runoff was determined in three soybean tillage systems with and without a 4 by 2 m tall fescue vegetative filter strip. Soil erosion plots were 4 by 22 m with 3% slope. Regression analysis was used to describe herbicide concentration in runoff, and to determine if vegetative filter strips reduced herbicide concentration. Analysis of covariance indicated no difference in concentration of metolachlor or metribuzin in runoff from the three tillage systems within any vegetative filter strip treatment. Metolachlor loss in 1991 was highest from the no-till monocrop without a vegetative filter strip, and it was 65g ha−1 or approximately 2% of the amount applied. In 1992 and 1993, the no-till doublecrop had a total loss of 120 and 147 g ha−1, respectively, approximately 4% of the amount applied. Similar results were noted with metribuzin, but total loss was as high as 46 g ha−1 or 11 % of the amount applied in 1993 from a no-till doublecrop system without a vegetative filter strip. When a vegetative filter strip was present, losses of metribuzin and metolachlor were reduced over 85% in 1993, and totaled 1.2 and 0.5%, respectively, of the amount applied. The vegetative filter strip reduced herbicide and suspended solids from runoff produced by a conventional-till production system to levels equal to or lower than a no-till doublecrop system.

Tall fescue vegetative filter strips 0.5 to 4.0 m wide were evaluated for their ability to reduce losses of metolachlor, metribuzin, and runoff (water and sediment) in conventionally tilled soybean. Differences in the parameters studied were significant between filter and no filter strips, regardless of filter strip width. Two days after treatment, metribuzin concentration in runoff from the unfiltered treatment was 231 ng ml−1; filter strips reduced this amount to 119 ng ml−1 or less. Similar trends were observed with metolachlor, with concentrations of 1,009 ng ml−1 from the unfiltered, whereas filter strips of any width reduced this to 523 ng ml−1 or less. Metribuzin loss during the growing season was 41 g ai ha−1, or 9.8% of the amount applied when no filter strip was present. The addition of a filter strip, regardless of width, reduced cumulative metribuzin losses to 11 g ha−1 or less. Similar results were noted with metolachlor. Filter strips, regardless of width, reduced cumulative runoff and sediment loss at least 46 and 83%, respectively.

A study was conducted to examine the effects of residence time and temperature on atrazine extractability and degradation in a sediment generated from Emporia sandy loam soil submerged under a water column. Sediments amended with 2.8 μg of atrazine were incubated at two temperatures (5 and 24 C), sampled at 0, 14, 28, 112, 168, 252, and 336 d, and then sequentially extracted once with 80 ml 0.01 M CaCl2 aqueous solution, three times with 25 ml of methanol/water mixture (4:1, v/v), and three times with 25 ml of methanol/water/formic acid (20:5:1, v/v pH 3.2) for a total of seven times. Extracts were analyzed for atrazine and metabolites using reverse phase high-performance liquid chromatography. The rate of bound residue formation was greater at 24 than at 5 C. About 30 and 60% of the 14C was bound (nonextractable) to sediments at 5 and 24 C, respectively. Water was less effective in extracting 14C residues from sediments incubated at 24 C than at 5 C. Acidification of the methanol/water mixture with formic acid during the last extraction step improved the removal of hydroxyatrazine from sediment. Atrazine degraded primarily to hydroxyatrazine (HA) and to a lesser extent to deethylatrazine (DEA). Although no DEA was found, HA at 43 μg kg−1 of sediment was detected 112 d after treatment at 5 C, indicating that chemical degradation could occur at a low temperature if sediments are incubated for extended periods of time. At 24 C, HA was found within 28 d and reached the maximum level at day 252. The results suggested that HA is the major metabolite of atrazine in the sediment; a significant fraction of the residue was unavailable for extraction, and this unextractable portion increased with residence time.

Three soybean production systems coupled with conventional tillage (CT) or no-tillage (NT) were evaluated for metolachlor and metribuzin loss in water from runoff. Metolachlor and metribuzin concentrations were similar in runoff from CT or NT soybean following winter wheat, with stubble burned, and CT or NT monocrop soybean. However, metolachlor and metribuzin concentrations were higher in runoff water from the CT doublecrop soybean planted into winter wheat stubble than NT. In all 3 yr of the study, the majority of total losses occurred in the first three runoff events. Total loss of metolachlor in runoff from the doublecrop system with winter wheat stubble present was 0.6% in 1991 to 1.1% in 1990 from CT, and 0.2% in 1990 to 0.6% in 1991 from the NT. Similar results were observed from the CT and NT doublecrop with burned winter wheat stubble and the monocrop systems. Metribuzin loss patterns were similar to metolachlor, but the fraction lost was slightly higher. Multi-variate regression was used to describe and predict herbicide losses, and R2values ranged from 0.66 to 0.98 for both metolachlor and metribuzin.

Indiana growers who purchase restricted-use pesticides are required to show the agrochemical dealer their private pesticide applicator license before the transaction can be completed. To keep the license current, growers may attend three private applicator recertification meetings or retake the exam every 5 yr. The meetings are county-based and must be a minimum of 2 h in length; they must include a topic mandated by the Office of the State Chemist. During the 2005/2006 private applicator recertification program (PARP) cycle, off-site movement of atrazine into surface water was the regulatory topic presented to 2,887 participants at 69 meetings. A team of individuals from different disciplines prepared educational materials to support the regulatory topic of the year. Surveys to assess grower awareness were conducted at the meetings and 1 yr later to monitor the long-term impact of the educational effort, and to evaluate which tactics were being adopted to reduce off-site movement of atrazine. Growers farming more than 800 ha had a higher degree of concern than small growers regarding the loss of atrazine as a weed management tool. Eighty-nine percent of the growers thought there would be a 314 to 1,255 kg/ha yield loss if atrazine was removed from the marketplace. Eighty-four percent of the growers estimated that weed control costs would increase $15 to $25/ha if no other products were available to replace atrazine. The three most acceptable management strategies to reduce atrazine movement were: more attention to label setback distances, establishment of grass filter strips around surface water, and reducing atrazine rates by tank mixing with other herbicides. The results of this project indicated that statewide programs such as this are effective in increasing awareness of an issue and documenting the impact of extension education programs.

Dominant users of Lake Okeechobee water resources are agricultural producers and recreational anglers These uses will be directly affected, should the lake become infested with zebra mussels. We employ a probabilistic bioeconomic simulation model to estimate the potential impact of zebra mussels on consumptive water uses, recreational angling, and wetland ecosystem services under alternative public management scenarios. Without public management, the expected net economic impact from zebra mussels is –$244.1 million over 20 years. Public investment in prevention and eradication will yield a net expected gain of +$188.7 million, a superior strategy to either prevention or eradication alone.

Escherichia coli is an indicator of fecal pollution used to mandate recreational and drinking water quality. Concentrations of culturable E. coli following contamination of surface water are determined by three factors: dilution; cell attachment to particulate material and settling or resuspension in the water column; and the net rate of change in viability. This study evaluated the variability in the latter parameter, and how predictive variation in death rate was of culturable population densities at the time of sampling. Water samples (N=232) with varying levels of E. coli contamination were collected from 46 discrete locations in four watersheds across Canada over a three-month period and enumerated for culturable E. coli by membrane filtration plate counting (T0EC). Water samples were again enumerated following a laboratory 24 h holding period at 30°C in the dark, and the difference considered the death rate (ΔEC). Relationships of T0EC and ΔEC with environmental and water chemistry factors were explored using step-wise multiple regression. The model predicting T0EC indicated that stream order, total rainfall seven days in advance of sampling day, total phosphorus, and ΔEC were the most significant contributors. The model predicting ΔEC indicated that turbidity and NH3+NH4 were the most important contributors. A model suggests that the persistence factor is less important than dilution (i.e. stream order) in describing E. coli densities, followed by factors that influence the loading of E. coli into watersheds.

Le site de l'Ile du Grand Gravier constitue un champ captant pour l'alimentation en eau potable de 80 000 équivalent-habitants. Sa situation dans le fleuve Rhône, à l'aval immédiat de l'agglomération lyonnaise et du couloir de la chimie, pose le problème de la vulnérabilité de la ressource en eau à une pollution du fleuve. Le site a fait l'objet de recherches hydrauliques et biologiques au niveau d'une parcelle expérimentale.L'étude des oligochètes a permis de dresser le diagnostic d'un état de pollution important du fleuve sur le secteur envisagé. Il apparaît de plus que certains taxons d'oligochètes, en particulier le genre Phallodrilus, décrivent une augmentation des échanges nappe-cours d'eau.L'ensemble de ces données souligne la vulnérabilité du site à une pollution transitant par le Rhône.Les résultats de cette première approche sont discutés. Il s'avère notamment que les aspects saisonniers n'ont pas été pris en considération. Le développement de la méthodologie est envisagé par l'étude complète de plusieurs autres parcelles.