Department of Civil and Environmental Engineering and Water Resources Research Center, University of Hawaii at Manoa, Honolulu, HI 96822, USA.
Nebraska Water Center, University of Nebraska, Lincoln, NE 68588, USA.
Water Res. 2015 Jun 15;77:107-118. doi: 10.1016/j.watres.2015.03.009. Epub 2015 Apr 1.
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.
一种大规模的淋溶评估工具不仅可以说明未监测地区的土壤（或地下水）易感性，还可以识别出可能受到农用化学品污染的潜在关注区域。本研究描述了如何将夏威夷全州淋溶工具进行修改，以用于农药和挥发性有机化合物，并将其扩展到全国土壤易感性评级评估的方法。在这项研究中，通过扩展土壤和补给图来覆盖美国（美国）的 48 个州，更新了该工具。此外，还使用了全国范围内（国家规模）的年度农药使用数字地图以及详细的土壤特性和每月补给率（高时空分辨率）来检查上层土壤中农药淋溶（负荷）的变化。结果表明，扩展工具成功划定了高到低易受选定农药影响的区域。对于百草枯，淋溶潜力很高；对于西玛津，淋溶潜力为中；对于 2,4-D 和草甘膦，淋溶潜力低至可以忽略不计。在记录了其在农业作物中广泛使用的美国西北部和中部地区，迁移到 0.5 米以下深度的百草枯的质量负荷量大大增加。但是，除了使用的农药量外，莠去津的年淋溶负荷量还受到其他因素的影响，这些因素决定了含水层的固有易感性，如土壤和补给特性。数字地图的空间和时间分辨率对农药的淋溶潜力有很大影响，这需要在数据可用性和准确性之间进行权衡。该工具的潜在应用包括对新兴污染物进行快速、大规模的易感性评估，由于缺乏完整的环境数据，通过包气带模型很难直接对其进行量化。
