RAPID - Evaluation of Soil Contamination due to Rio Grande Flooding July 2010

本研究的主要目标是评估污染物的稳定性土壤中的影响，最近的洪水格兰德河附近的拉雷多，得克萨斯州。 格兰德河洪水在2010年7月8日达到峰值，在12.8米（42英尺）处的流量超过4,000立方米/秒（410,000立方英尺）。高于平均流量阶段。 [Note主洪水位被认为比平均水位高9 m（30 ft）。] 农业、工业、采矿、航运和市政用地被洪水淹没，成为一系列污染物的来源，包括重金属和有机物。 随着洪水沃茨的退去，这些污染物沉积到河流附近的土壤中。 该项目将评估受洪水影响的格兰德河和土壤中重金属（全面板）和代表性有机化合物（多溴二苯醚、三氯生、环丙沙星和阿特拉津）的保留和移动情况。 从2010年5月开始，从六个地点收集了水样，在洪水期间更频繁地取样，以更好地量化污染物沉积率，并将在整个项目期间继续进行。 将对每次取样进行现场水质参数、流速、营养物和有关化学品（水和颗粒结合物）评估，以确定高流量（洪水）条件和平均流量条件下的污染程度。 选择了两个地点进行采样-未开发的土地和那些用于自然步行毗邻河流。 在每个地点建立三个样带，每个样带的一半覆盖受影响的土壤（1毫米至2厘米的沉积物）和未受影响的土壤。 在洪水沃茨消退后2天内采集初始样本，并将在第6周、第12周和第24周再次采集样本。 收集样品，并按层位（表面/沉积物沉积、根系渗透深度和深层土壤）进行分段。 将对每一种土壤的总体土壤条件和感兴趣的污染物进行评价。 这项研究将使我们能够更好地评估这些化合物在根际由于进一步的自然和人为干扰的理化行为。 对流域洪泛区和邻近土地的实地采样将帮助我们绘制该地区水和土壤中污染物的分布图。 该项目将有助于对下格兰德河农业区的实际污染物水平以及这些污染物对重要商业作物的潜在影响进行全系统评估。 这一洪水事件将使我们能够更好地模拟污染物的行为在根际有限的操纵自然系统。 直接与农民合作，这也将有助于我们更好地了解在格兰德河流域使用再生水灌溉对土壤健康和作物生产力的潜在影响。 最终，这项研究将扩展到微生物群落的检查，以支持在人为污染物存在下营养动态和土壤质量的可持续性。

The primary goal of this research is to assess contaminant stability within soils impacted by recent flooding of the Rio Grande near Laredo, Texas. The Rio Grande flood peaked on 8 July 2010 with a flow exceeding 4,000 m3/s (410,000 cfs) at 12.8 m (42 ft.) above the average flow stage. [Note that major flood stage is considered to be 9 m (30 ft) above the average flow stage.] Agricultural, industrial, mining, shipping and municipal lands were flooded and served as sources which mobilized a suite of contaminants including heavy metals and organics. As flood waters receded, these contaminants were deposited into soils adjacent to the river. This project will assess the retention and movement of heavy metals (full panel), and representative organic compounds (PBDE, Triclosan, Ciprofloxacin, and Atrazine) within the Rio Grande and soils impacted by the flood. Water samples have been collected from six locations beginning in May 2010, with more frequent sampling during the flood to better quantify the contaminant deposition rate, and will continue throughout this project. In situ water quality parameters, flow rate, nutrients and the chemicals of interest (aqueous and particle bound) will be assessed for each sampling to determine the level of contamination during both high-flow (flood) conditions and average-flow conditions. Two sites were selected for sampling - undeveloped lands and those used for a nature walk adjacent to the river. Three transects were established at each site with half of each transect covering impacted (1 mm - 2 cm of sediment deposition) and non-impacted soils. Initial samples were collected within 2 days of the flood waters receding, and will be collected again at 6 weeks, 12 weeks and 24 weeks. Samples are collected and segmented by horizon (surface/sediment deposition, root penetration depth and deep soils). Each will be evaluated for overall soil conditions and the contaminants of interests. This research will allow us to better assess the physiochemical behavior of these compounds within the rhizosphere due to further natural and anthropogenic disturbances. Field sampling of the watershed floodplain and adjacent lands will help us to map contaminant distributions in both water and soil in the region. This project will contribute to a whole system assessment of actual contaminant levels in the lower Rio Grande agricultural region and the potential effects of these contaminants on commercially important crops. This flooding event will allow us to better model contaminant behavior within the rhizosphere with limited manipulations of the natural system. Working directly with farmers, this will also help us to better understand the potential impacts on soil health and crop productivity of using recycled water for irrigation in the Rio Grande Valley. Eventually this research will extend to the examination of the microbial community to support sustainability of nutrient dynamics and soil quality in the presence of anthropogenic contaminants.