Department of Biological Sciences, University of Texas at El Paso, El Paso, TX 79912, USA.
Water Sci Technol. 2010;62(3):501-9. doi: 10.2166/wst.2010.323.
The Rio Grande, which forms the United States-Mexico border for much of its course, receives diverse pollutants from both urban and agricultural areas, most notably in the sister cities of El Paso (TX, USA)-Ciudad Juárez (CHI, Mexico). This study aimed to describe regional trends in water quality in waters near the El Paso-Ciudad Juárez metroplex and to examine the potential for water quality improvement through the use of a created wetland. Very few differences in nutrient chemistry were found among drains, canals and the Rio Grande, with the exception of elevated chloride and lower phosphorus levels found in the drains. Overall, chloride concentrations increased with distance downstream, likely due to concentration of salts via evaporation from irrigated agriculture. A wastewater treatment plant (WWTP) contributed substantially to total phosphorus and nitrate levels, which, together with ammonia, tended to exceed state criteria for water quality downstream of the WWTP outflow. The created Rio Bosque wetlands reduced nitrate concentrations in the water, possibly via denitrification enhanced by algae; algae increased in biomass as water flowed through the wetlands. However, the diversion of water for irrigated agriculture, resulting in the absence of water, and thus aquatic plants, in the wetland in the summer has limited the ability of this wetland to improve regional water quality.
格兰德河（Rio Grande）在其大部分流程中构成了美国和墨西哥的边境，从城市和农业区接收了各种污染物，尤其是在埃尔帕索（美国得克萨斯州）-华雷斯城（墨西哥奇瓦瓦州）这对姐妹城市。本研究旨在描述埃尔帕索-华雷斯都会区附近水域的水质区域趋势，并通过创建湿地来考察水质改善的潜力。除了在排水渠中发现的氯化物升高和磷含量较低外，排水渠、运河和格兰德河之间的营养化学物质差异很小。总体而言，氯离子浓度随下游距离的增加而增加，这可能是由于灌溉农业蒸发导致盐分浓缩所致。污水处理厂（WWTP）对总磷和硝酸盐水平有很大贡献，这与氨一起，在 WWTP 流出物的下游往往超过了水质的州标准。创建的 Rio Bosque 湿地减少了水中的硝酸盐浓度，这可能是通过藻类增强的反硝化作用实现的；藻类随着水在湿地中的流动而增加了生物量。然而，为灌溉农业引水导致湿地在夏季缺水，从而导致水生植物缺失，这限制了该湿地改善区域水质的能力。
