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A large-scale leaching assessment tool not only illustrates soil (or groundwater) vulnerability in unmonitored areas, but also can identify areas of potential concern for agrochemical contamination. This study describes the methodology of how the statewide leaching tool in Hawaii modified recently for use with pesticides and volatile organic compounds can be extended to the national assessment of soil vulnerability ratings. For this study, the tool was updated by extending the soil and recharge maps to cover the lower 48 states in the United States (US). In addition, digital maps of annual pesticide use (at a national scale) as well as detailed soil properties and monthly recharge rates (at high spatial and temporal resolutions) were used to examine variations in the leaching (loads) of pesticides for the upper soil horizons. Results showed that the extended tool successfully delineated areas of high to low vulnerability to selected pesticides. The leaching potential was high for picloram, medium for simazine, and low to negligible for 2,4-D and glyphosate. The mass loadings of picloram moving below 0.5 m depth increased greatly in northwestern and central US that recorded its extensive use in agricultural crops. However, in addition to the amount of pesticide used, annual leaching load of atrazine was also affected by other factors that determined the intrinsic aquifer vulnerability such as soil and recharge properties. Spatial and temporal resolutions of digital maps had a great effect on the leaching potential of pesticides, requiring a trade-off between data availability and accuracy. Potential applications of this tool include the rapid, large-scale vulnerability assessments for emerging contaminants which are hard to quantify directly through vadose zone models due to lack of full environmental data. [ABSTRACT FROM AUTHOR]

Riverbank filtration (RBF) has been used for many decades in Europe and the United States to provide drinking water to communities located on riverbanks. In India, the development of RBF has the potential to provide drinking water to many cities located on the Ganga Plains currently using surface water as a source for their public water supply. Water diversion for irrigation and discharge of wastewater to rivers with extremely low flows has aggravated the water supply situation for many Indian cities using surface water. A number of Indian cities, with source waters of significantly varying quality, are already using RBF. In most of these cities no significant additional treatment is provided to the filtrate for their water supply. The objective of this article is to examine selected operating bank filtration sites in India (that have been investigated since 2005) and to elucidate additional potential RBF sites based on water problems and hydrogeologic suitability. A summary of selected operational RBF systems in Ahmedabad, Delhi, Haridwar, Mathura, Medinipur and Kharagpur, Nainital, Patna and Srinagar and their ability to produce potable water is provided. Analysis of the suitability of RBF for Allahabad, Bhubaneswar, Guwahati, and Vijayawada, based on hydrogeology and land use, is also provided. [ABSTRACT FROM AUTHOR]

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More and more US water providers are looking into riverbank filtration (RBF) systems as a simple, low-cost, and effective pretreatment process for drinking water production. However, many utilities are not aware that RBF is also ideal for handling chemical shock loads that may result from emergency spills or spring flooding in agricultural watersheds. With RBF, dissolved and suspended contaminants are reduced as the water passes through the river sediment-aquifer system. In addition, RBF systems can moderate peak concentrations of chemicals and delay their arrival at the pumping wells, providing utilities with ample time to take necessary treatment action. In this research, a model was used to investigate the effectiveness of RBF systems in mitigating chemical shock loads. Scenarios simulated both horizontal and vertical wells, with riverbed and bank hydraulic properties varying as a function of river stage. Results indicated that RBF wells subject to chemical shock loads do not allow significant breakthrough of spilled chemicals if the bank material is low in conductivity or, if the bank material is highly conductive, wells are placed away from the river. The Long Term 2 Enhanced Surface Water Treatment Rule's provision of a 0.5- to 1.0-log filtration credit has generated increased interest in RBF systems. RBF's ability to mitigate chemical contamination from spills, agricultural chemical applications, and chemical runoff during floods should make the process even more attractive to US water suppliers. [ABSTRACT FROM AUTHOR]

Extreme climate events including heat waves and droughts are projected to become more frequent under future climate change conditions. However, the mechanisms between soybean yields and climate factors, specifically involving variable rainfall and high heat episodes, are still unclear, particularly with respect to spatial trends in the United States (US) Midwest. A recently modified version of the model GLYCIM was used to evaluate rainfed soybean production across 12 states at a 10 km spatial resolution for three time periods (2011-2020, 2051-2060, 2091-2099) under Representative Concentration Pathway (RCP) scenarios 4.5 and 8.5. Results showed that except for the northernmost Midwest counties, most of the current rainfed cropping system in the Midwest would suffer a 24.6-47.4 % yield loss without considering the CO 2 fertility effect. Incorporating the effect of elevated CO 2 showed a smaller yield loss of 11.6-29.5 %. The increased frequency of extreme degree days (EDD) or accumulation of hourly temperatures above 30 °C associated with increased vapor pressure deficit (VPD) played a key role in contributing to water deficits and resultant crop losses under these future climate conditions. Although a relatively weak relationship between summer rainfall and crop yield was observed, decreased rainfall caused VPD to increase which induced crop water deficits. These findings suggest that it is crucial to consider VPD along with high temperature and low rainfall trends simultaneously for development of potential management or breeding-based adaptative strategies for soybean., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)