Joshua I. Linard

Variations in Pesticide Leaching Related to Land Use, Pesticide Properties, and Unsaturated Zone Thickness

Pesticide leaching through variably thick soils beneath agricultural fields in Morgan Creek, Maryland was simulated for water years 1995 to 2004 using LEACHM (Leaching Estimation and Chemistry Model). Fifteen individual models were constructed to simulate five depths and three crop rotations with associated pesticide applications. Unsaturated zone thickness averaged 4.7 m but reached a maximum of 18.7 m. Average annual recharge to ground water decreased from 15.9 to 11.1 cm as the unsaturated zone increased in thickness from 1 to 10 m. These point estimates of recharge are at the lower end of previously published values, which used methods that integrate over larger areas capturing focused recharge in the numerous detention ponds in the watershed. The total amount of applied and leached masses for five parent pesticide compounds and seven metabolites were estimated for the 32-km2 Morgan Creek watershed by associating each hectare to the closest one-dimensional model analog of model depth and crop rotation scenario as determined from land-use surveys. LEACHM parameters were set such that branched, serial, first-order decay of pesticides and metabolites was realistically simulated. Leaching is predicted to be greatest for shallow soils and for persistent compounds with low sorptivity. Based on simulation results, percent parent compounds leached within the watershed can be described by a regression model of the form e(-depth) (a ln t1/2-b ln K OC) where t1/2 is the degradation half-life in aerobic soils, K OC is the organic carbon normalized sorption coefficient, and a and b are fitted coefficients (R2 = 0.86, p value = 7 x 10(-9)).

Assessment of historical surface-water quality data in southwestern Colorado, 1990-2005

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Interactive energy atlas for Colorado and New Mexico: an online resource for decisionmakers

Throughout the western United States, increased demand for energy is driving the rapid development of oil, gas (including shale gas and coal-bed methane), and uranium, as well as renewable energy resources such as geothermal, solar, and wind. Much of the development in the West is occurring on public lands, including those under Federal and State jurisdictions. In Colorado and New Mexico, these public lands make up about 40 percent of the land area. Both States benefit from the revenue generated by energy production, but resource managers and other decisionmakers must balance the benefits of energy development with the potential consequences for ecosystems, recreation, and other resources. Although a substantial amount of geospatial data on existing energy development and energy potential is available, much of this information is not readily accessible to natural resource decisionmakers, policymakers, or the public. Furthermore, the data often exist in varied formats, requiring considerable processing before these datasets can be used to evaluate tradeoffs among resources, compare development alternatives, or quantify cumulative effects. To allow for a comprehensive evaluation among different energy types, an interdisciplinary team of U.S. Geological Survey (USGS) scientists has developed an online Interactive Energy Atlas (Energy Atlas) (http://my.usgs.gov/eerma/) for Colorado and New Mexico. The purpose of the Energy Atlas is to facilitate access to geospatial data related to energy resources, energy infrastructure, and natural resources that may be affected by energy development. The Energy Atlas is designed to meet the needs of varied users, including geographic information system (GIS) analysts, resource managers, policymakers, and the public, who seek information about energy in the western United States. Currently (2013), the Energy Atlas has two primary capabilities: a GIS data viewer and an interactive map gallery.