Dicamba and 2,4-D residues following applicator cleanout: A potential point source to the environment and worker exposure

This paper presents a survey of pesticide residues in tanks following application and throughout the cleanout procedure as conducted by 46 volunteer operators across Colorado. While many pesticides were detected, this paper focuses on dicamba and 2,4-D, which were detected by liquid chromatography/tandem mass spectroscopy (LC-MS/MS). An exponential decrease in concentration was observed with sequential rinses, although this decrease may be more rapid for more water-soluble pesticides. More than 95% of the pesticide in the prerinse solution was removed by the end of the third rinse in all but three operator samples. Concentrations after three rinses were 0.41 ± 0.25 and 3.3 ± 1.1 mg/L for dicamba and 2,4-D, respectively. These concentrations suggest that the recommended practice of three rinses may not be adequate to eliminate off-target effects or point sources of pesticide waste, and that the recommended standard of personal protective equipment is essential to prevent worker exposure to the chemicals.

Implications:?This paper demonstrates that the waste generated during cleanout of pesticide application devices constitutes a potential source of pollution and worker exposure. In particular, while the first rinse of pesticide containers is often treated as hazardous waste and reapplied to crops, the remaining rinses are not. This work demonstrates that the wastewater generated in subsequent rinses can have high enough concentrations to impact worker health, cause off-target effects on crops, and potentially constitute a point source of pesticides. The practical implication is for improved recommendations and regulations regarding pesticide applicators and their cleanout process.     

Predicting estuarine sediment metal concentrations and inferred ecological conditions: an information theoretic approach

Empirically derived relationships associating sediment metal concentrations with degraded ecological conditions provide important information to assess estuarine condition. Resources limit the number, magnitude, and frequency of monitoring activities to acquire these data. Models that use available information and simple statistical relationships to predict sediment metal concentrations could provide an important tool for environmental assessment. We developed 45 predictive models for the total concentrations of copper, lead, mercury, and cadmium in estuarine sediments along the Southern New England and Mid-Atlantic regions of the United States. Using information theoretic model-averaging approaches, we found total developed land and percent silt/clay of estuarine sediment were the most important variables for predicting the presence of all four metals. Estuary area, river flow, tidal range, and total agricultural land varied in their importance. The model-averaged predictions explained 78.4, 70.5, 56.4, and 50.3% of the variation for copper, lead, mercury, and cadmium, respectively. Overall prediction accuracies of selected sediment benchmark values (i.e., effects ranges) were 83.9, 84.8, 78.6, and 92.0% for copper, lead, mercury, and cadmium, respectively. Our results further support the generally accepted conclusion that sediment metal concentrations are best described by the physical characteristics of the estuarine sediment and the total amount of urban land in the contributing watershed. We demonstrated that broad-scale predictive models built from existing monitoring data with information theoretic model-averaging approaches provide valuable predictions of estuarine sediment metal concentrations and show promise for future environmental modeling efforts in other regions.     

The development and application of water management sustainability indicators in Brazil and Scotland

This paper reports the formulation and application of a framework of catchment-level water resource management indicators designed to integrate environmental, economic and social aspects of sustainability. The framework of nine indicators was applied to the River Dee and River Sinos catchments in Scotland and Brazil, respectively, following an indicator selection process that involved inputs from water management professionals in both countries, and a pilot exercise in Scotland. The framework was found to capture a number of key sustainability concerns, and was broadly welcomed by water resource managers and experts as a means of better understanding sustainable water resource management. Issues relating to poor water quality and public water supply were particularly prominent in the findings for the Sinos, while findings for the Dee suggested that more attention might be focused on building institutional capacity and public participation in catchment management. The use of some proxy indicators was required in both catchments due to poor data availability, and this problem may hinder the further development of indicator frameworks that attempt to better integrate environmental, economic and social dimensions of sustainability.     

Impact of growth conditions on transport behavior of E. coli

The aim of this investigation is to determine the effect that growth solution has on the cell surface properties and transport behavior of eleven Escherichia coli isolates through saturated porous media. The two growth solutions used were a standard laboratory growth medium (LB) and a dairy manure extract solution. In general, cells grown in manure extract were more hydrophobic, had a more negative zeta potential, had lower amounts of surface macromolecules, and had lower attachment efficiencies than isolates grown in LB. An inverse relationship between the natural log of zeta potential and the attachment efficiency of the isolates for the cells grown in LB media was the only statistically significant correlation observed between transport behavior and cell characteristics of the isolates. This study shows the need to consider growth conditions when studying bacteria to better mimic the environmental stresses that bacteria undergo in the natural environment. This approach could lead to a better understanding of the behavior of manure-derived bacteria in aquatic and terrestrial environments.     

Reconnecting to the Biosphere

Humanity has emerged as a major force in the operation of the biosphere, with a significant imprint on the Earth System, challenging social-ecological resilience. This new situation calls for a fundamental shift in perspectives, world views, and institutions. Human development and progress must be reconnected to the capacity of the biosphere and essential ecosystem services to be sustained. Governance challenges include a highly interconnected and faster world, cascading social-ecological interactions and planetary boundaries that create vulnerabilities but also opportunities for social-ecological change and transformation. Tipping points and thresholds highlight the importance of understanding and managing resilience. New modes of flexible governance are emerging. A central challenge is to reconnect these efforts to the changing preconditions for societal development as active stewards of the Earth System. We suggest that the Millennium Development Goals need to be reframed in such a planetary stewardship context combined with a call for a new social contract on global sustainability. The ongoing mind shift in human relations with Earth and its boundaries provides exciting opportunities for societal development in collaboration with the biosphere--a global sustainability agenda for humanity.     

Estimation of NH3 bi-directional flux from managed agricultural soils

The Community Multi-Scale Air Quality model (CMAQ) is used to assess regional air quality conditions for a wide range of chemical species throughout the United States (U.S.). CMAQ representation of the regional nitrogen budget is limited by its treatment of ammonia (NH₃) soil emission from, and deposition to underlying surfaces as independent rather than tightly coupled processes, and by its reliance on soil emission estimates that do not respond to variable meteorology and ambient chemical conditions. The present study identifies an approach that addresses these limitations, lends itself to regional application, and will better position CMAQ to meet future assessment challenges. These goals were met through the integration of the resistance-based flux model of Nemitz et al. (2001) with elements of the United States Department of Agriculture EPIC (Environmental Policy Integrated Climate) model. Model integration centers on the estimation of ammonium and hydrogen ion concentrations in the soil required to estimate soil NH₃ flux. The EPIC model was calibrated using data collected during an intensive 2007 field study in Lillington, North Carolina. A simplified process model based on the nitrification portion of EPIC was developed and evaluated. It was then combined with the Nemitz et al. (2001) model and measurements of near-surface NH₃ concentrations to simulate soil NH₃ flux at the field site. Finally, the integrated flux (emission) results were scaled upward and compared to recent national ammonia emission inventory estimates. The integrated model results are shown to be more temporally resolved (daily), while maintaining good agreement with established soil emission estimates at longer time-scales (monthly). Although results are presented for a single field study, the process-based nature of this approach and NEI comparison suggest that inclusion of this flux model in a regional application should produce useful assessment results if nationally consistent sources of driving soil and agricultural management information are identified.     

Comparison and Verification of Bacterial Water Quality Indicator Measurement Methods Using Ambient Coastal Water Samples

During the summers of 2002 and 2004, in-stream integrated flow and concentration measurements for the total dissolved solids in the Cheyenne River, South Dakota, USA was conducted in order to compare the obtained actual field measurements with the predictions values made by the Bureau of Reclamation in the Environmental Impact Statement. In comparison to the actual field measurements conducted in this study, The Bureau of Reclamation extension of a small database used in the analysis for the impact of operations at the Angostura Unit over the past 50 years and into the future to predict the annual total dissolved solid loadings doesn't represent the actual loading values and various conditions in the study area. Additional integrated flow and concentration sampling is required to characterize the impact of the current Angostura Dam operations and Angostura Irrigation District return flows on the Cheyenne River in different seasons of the year.     

Heavy metal contamination in bats in Britain

Toxic metals are bioaccumulated by insectivorous mammals but few studies (none from Britain) have quantified residues in bats. We measured renal mercury (Hg), lead (Pb) and cadmium (Cd) concentrations in bats from south-west England to determine how they varied with species, sex, age, and over time, and if they were likely to cause adverse effects. Residues were generally highest in whiskered bats (Myotis mystacinus). Compared with other species, pipistrelle (Pipistrellus spp) and Natterer's bats (Myotis nattereri) had significantly lower kidney Hg and Pb concentrations, respectively. Renal Hg increased over time in pipistrelles but the contributory sources are unknown. Kidney Pb did not decrease over time despite concurrent declines in atmospheric Pb. Overall, median renal metal concentrations were similar to those in bats from mainland Europe and 6- to 10-fold below those associated with clinical effect, although 5% of pipistrelles had kidney Pb residues diagnostic of acute lead poisoning.     

Improving supplementary feeding in species conservation

Supplementary feeding is often a knee‐jerk reaction to population declines, and its application is not critically evaluated, leading to polarized views among managers on its usefulness. Here, we advocate a more strategic approach to supplementary feeding so that the choice to use it is clearly justified over, or in combination with, other management actions and the predicted consequences are then critically assessed following implementation. We propose combining methods from a set of specialist disciplines that will allow critical evaluation of the need, benefit, and risks of food supplementation. Through the use of nutritional ecology, population ecology, and structured decision making, conservation managers can make better choices about what and how to feed by estimating consequences on population recovery across a range of possible actions. This structured approach also informs targeted monitoring and more clearly allows supplementary feeding to be integrated in recovery plans and reduces the risk of inefficient decisions. In New Zealand, managers of the endangered Hihi (Notiomystis cincta) often rely on supplementary feeding to support reintroduced populations. On Kapiti island the reintroduced Hihi population has responded well to food supplementation, but the logistics of providing an increasing demand recently outstretched management capacity. To decide whether and how the feeding regime should be revised, managers used a structured decision making approach informed by population responses to alternative feeding regimes. The decision was made to reduce the spatial distribution of feeders and invest saved time in increasing volume of food delivered into a smaller core area. The approach used allowed a transparent and defendable management decision in regard to supplementary feeding, reflecting the multiple objectives of managers and their priorities.