Modeling of Escherichia coli Fluxes on a Catchment and the Impact on Coastal Water and Shellfish Quality1

Bougeard, Morgane, Jean‐Claude Le Saux, Nicolas Pérenne, Claire Baffaut, Marc Robin, and Monique Pommepuy, 2011. Modeling of Escherichia coli Fluxes on a Catchment and the Impact on Coastal Water and Shellfish Quality. Journal of the American Water Resources Association (JAWRA) 1‐17. DOI: 10.1111/j.1752‐1688.2011.00520.x Abstract: The simulation of the impact of Escherichia coli loads from watersheds is of great interest for assessing estuarine water quality, especially in areas with shellfish aquaculture or bathing activities. For this purpose, this study investigates a model association based on the Soil and Water Assessment Tool (SWAT) coupled with a hydrodynamic model (MARS 2D; IFREMER). Application was performed on the catchment and estuary of Daoulas area (France). The daily E. coli fluxes simulated by SWAT are taken as an input in the MARS 2D model to calculate E. coli concentrations in estuarine water and shellfish. Model validation is based on comparison of frequencies: a strong relationship was found between calculated and measured E. coli concentrations for river quality (r² = 0.99) and shellfish quality (r² = 0.89). The important influence of agricultural practices and rainfall events on the rapid and large fluctuations in E. coli fluxes from the watershed (reaching three orders of magnitude in <24 hours) is one main result of the study. Response time in terms of seawater quality degradation ranges from one to two days after any important rainfall event (greater than 10 mm/day) and the time for estuary to recover good water quality also mainly depends on the duration of the rainfall. In the estuary, three effects (rainfall, tidal dilution, and manure spreading) have been identified as important influences.     

Nonstationary Water Planning: An Overview of Several Promising Planning Methods1

Waage, Marc D. and Laurna Kaatz, 2011. Nonstationary Water Planning: An Overview of Several Promising Planning Methods. Journal of the American Water Resources Association (JAWRA) 47(3):535‐540. DOI: 10.1111/j.1752‐1688.2011.00547.x Abstract: Climate change is challenging the way water utilities plan for the future. Observed warming and climate model projections now call into question the stability of future water quantity and quality. As water utilities cope with preparing for the large range of possible changes in climate and the resulting impacts on their water systems, many are searching for planning techniques to help them consider multiple possible conditions to better prepare for a different, more uncertain, future. Many utilities need these techniques because they cannot afford to delay significant decisions while waiting for scientific improvements to narrow the range of potential climate change impacts. Several promising methods are being tested in water utility planning and presented here for other water utilities to consider. The methods include traditional scenario planning, classic decision making, robust decision making, real options, and portfolio planning. Unfortunately, for utilities vulnerable to climate change impacts, there is no one‐size‐fits‐all planning solution. Every planning process must be tailored to the needs and capabilities of the individual utility.     

On the meta-analysis of response ratios for studies with correlated and multi-group designs

A common effect size metric used to quantify the outcome of experiments for ecological meta-analysis is the response ratio (RR): the log proportional change in the means of a treatment and control group. Estimates of the variance of RR are also important for meta-analysis because they serve as weights when effect sizes are averaged and compared. The variance of an effect size is typically a function of sampling error; however, it can also be influenced by study design. Here, I derive new variances and covariances for RR for several often-encountered experimental designs: when the treatment and control means are correlated; when multiple treatments have a common control; when means are based on repeated measures; and when the study has a correlated factorial design, or is multivariate. These developments are useful for improving the quality of data extracted from studies for meta-analysis and help address some of the common challenges meta-analysts face when quantifying a diversity of experimental designs with the response ratio.     

A design of experiments for statistically predicting risk of adverse health effects on drivers exposed to vertical vibrations

An injury risk factor (IRF), which indicates the risk of adverse health effect to lumbar rachis arising from mechanical vibrations, is developed. Experiments have been conducted that consider acceleration levels at the seat of drivers, posture, morphology, density, damping rate and body mass as independent variables. A parametric finite-element model of the lumbar rachis has been generated. It is shown that the IRF increases with ageing and an IRF of 30% is proposed as a threshold for fatigue purposes. This level is reached if a peak acceleration level greater than 3 m/s2 is applied to a light (55 kg) and an old driver with a low bone density and a damping rate of 20%. This vibration threshold must be reduced to 2.7 m/s2 if the driver?s weight increases to 75 kg and to 2 m/s2 if the driver is heavy (98 kg).     

The desorption of antimony(V) from sediments, hydrous oxides, and clay minerals by carbonate, phosphate, sulfate, nitrate, and chloride

The desorption of antimony, Sb(V), from two sediment samples by phosphate, carbonate, sulfate, chloride, and nitrate at pH 8 was examined. One highly contaminated sediment sample was taken from an Sb mine (Goesdorf, Luxembourg); the other sample was the certified reference material PACS-2 (marine sediment). Phosphate was found to have a strong mobilizing ability, whereas that of carbonate was in general weaker. For comparison, and to understand better the possible importance of individual components of the sediments, desorption experiments were performed on pure phases (i.e., hydrous oxides of Fe, Mn, and Al) and the clay minerals kaolinite and montmorillonite. In the cases of hydrous metal oxides, Sb(V) was most effectively desorbed by phosphate, followed by carbonate. Phosphate also desorbed Sb(V) from the clay minerals, whereas carbonate had no effect. The pH dependence of adsorption of Sb(V) in the absence and presence of carbonate revealed that adsorption densities were higher (except in the case of montmorillonite) in the absence of carbonate, suggesting a competition between carbonate and [Sb(OH)] for surface sites generally and a lowering of surface charge in the case of hydrous aluminum oxide. The observations are unlikely to be due to ionic strength effects because activity coefficients in the blank and spiked solutions differ by <4%. Desorption experiments on sediments with varying concentrations of phosphate and carbonate demonstrated that at environmentally relevant concentrations, desorption by phosphate is negligible, whereas the effect of carbonate is not. Sulfate, chloride, and nitrate generally had little effect. The proportion of Sb desorbed in blank experiments coincides with that mobilized in the first fraction of the Bureau Communautaire de Référence (BCR) sequential extraction (easily exchangeable and carbonate-bound fraction).     

Use of a Wetland Index to Evaluate Changes in Riparian Vegetation After Livestock Exclusion 1

Abstract: A method was developed to characterize ecological integrity of riparian sites based on the abundance of hydric species. This wetland index can be calculated with species data, or with community type data as performed here. Classified riparian community types were used to describe vegetation at 14 livestock exclosures and adjacent grazed areas. Community type wetland index values were generated and used to calculate site wetland index values. It was hypothesized that removal of livestock would result in higher wetland index values because of release from herbivory and decreased physical disturbance of vegetation, streambanks, and soil. The wetland index for exclosures was about 12% higher than grazed sites; differences were statistically significant (p < 0.01) based on paired t‐tests. The increase in hydric vegetation after livestock exclusion may have contributed to the greater bank stability (p = 0.002) and smaller width‐to‐depth ratio (p = 0.005) in exclosures. Challenges were encountered in using community types to describe and compare site vegetation, which could be avoided with species data collection. The wetland index can be a tool to monitor sites over time, compare sites with similar environments, or compare sites for which environmental differences can be accounted.     

A framework for habitat monitoring and climate change modelling: construction and validation of the Environmental Stratification of Estonia

Environmental stratifications provide the framework for efficient surveillance and monitoring of biodiversity and ecological resources, as well as modelling exercises. An obstacle for agricultural landscape monitoring in Estonia has been the lack of a framework for the objective selection of monitoring sites. This paper describes the construction and testing of the Environmental Stratification of Estonia (ESE). Principal components analysis was used to select the variables that capture the most amount of variation. Seven climate variables and topography were selected and subsequently subjected to the ISODATA clustering routine in order to produce relatively homogeneous environmental strata. The ESE contains eight strata, which have been described in terms of soil, land cover and climatic parameters. In order to assess the reliability of the stratification procedure for the selection of monitoring sites, the ESE was compared with the previous map of Landscape Regions of Estonia and correlated with five environmental data sets. All correlations were significant. The stratification has therefore already been used to extend the current series of samples in agricultural landscapes into a more statistically robust series of monitoring sites. The potential for applying climate change scenarios to assess the shifts in the strata and associated ecological impacts is also examined.     

Spatial relationships between lead sources and children’s blood lead levels in the urban center of Indianapolis (USA)

Urban children remain disproportionately at risk of having higher blood lead levels than their suburban counterparts. The Westside Cooperative Organization (WESCO), located in Marion County, Indianapolis, Indiana, has a history of children with high blood lead levels as well as high soil lead (Pb) values. This study aims at determining the spatial relationship between soil Pb sources and children’s blood lead levels. Soils have been identified as a source of chronic Pb exposure to children, but the spatial scale of the source–recipient relationship is not well characterized. Neighborhood-wide analysis of soil Pb distribution along with a furnace filter technique for sampling interior Pb accumulation for selected homes (n = 7) in the WESCO community was performed. Blood lead levels for children aged 0–5 years during the period 1999–2008 were collected. The study population’s mean blood lead levels were higher than national averages across all ages, race, and gender. Non-Hispanic blacks and those individuals in the Wishard advantage program had the highest proportion of elevated blood lead levels. The results show that while there is not a direct relationship between soil Pb and children’s blood lead levels at a spatial scale of ~100 m, resuspension of locally sourced soil is occurring based on the interior Pb accumulation. County-wide, the largest predictor of elevated blood lead levels is the location within the urban core. Variation in soil Pb and blood lead levels on the community level is high and not predicted by housing stock age or income. Race is a strong predictor for blood lead levels in the WESCO community.