Interlandi Sebastian J, Crockett Christopher S
School of Environmental Science, Engineering and Policy, Drexel University, 32nd and Chestnut Streets, Philadelphia, PA 19104, USA.
Water Res. 2003 Apr;37(8):1737-48. doi: 10.1016/S0043-1354(02)00574-2.
Climate, flow rate and land use are all known drivers of water quality in river systems, but determining the relative influences of these factors remains a significant challenge for aquatic science and management. Long-term data from the Schuylkill River at Philadelphia is assessed here in an attempt to ascertain the separate and combined influence of these major drivers on water quality in a developed watershed. Water quality measures including nutrients, conservative solutes and bacteria all elicited distinct seasonal patterns driven primarily by river discharge. Mass transport rates of sodium and chloride have increased with time, and were elevated in winter, presumably as a function of road salt deposition. A steady increase in developed land area in the watershed has occurred in recent decades, which allowed the use of time as a surrogate parameter for regional development in the construction of multiple factor linear models predicting the relative influences of precipitation, river discharge and developed land area on river water quality. Linear models predicting annually averaged water quality measures showed the effects of precipitation, discharge and developed land area to be of nearly equal importance in regulating levels of conductivity, alkalinity, sodium, and chloride in the river. Models predicting water quality variables for discrete samples demonstrated that river flow was the major determinant of daily variability in alkalinity, conductivity, hardness and calcium levels, while still resolving the highly significant influence of watershed development on water quality. Increases in solute transport in the Schuylkill River in recent decades appear to be the direct result of modern suburban development in the watershed.
气候、流速和土地利用都是河流系统水质的已知驱动因素，但确定这些因素的相对影响对水生科学和管理来说仍然是一项重大挑战。本文评估了来自费城斯库尔基尔河的长期数据，试图确定这些主要驱动因素对一个已开发流域水质的单独和综合影响。包括营养物质、保守溶质和细菌在内的水质指标都呈现出明显的季节性模式，主要由河流流量驱动。钠和氯的质量传输速率随时间增加，并且在冬季升高，这可能是道路盐分沉积的作用。近几十年来，该流域已开发土地面积稳步增加，这使得在构建预测降水、河流流量和已开发土地面积对河流水质相对影响的多因素线性模型时，可以将时间用作区域发展的替代参数。预测年度平均水质指标的线性模型表明，降水、流量和已开发土地面积在调节河流中电导率、碱度、钠和氯的水平方面的影响几乎同等重要。预测离散样本水质变量的模型表明，河流流量是碱度、电导率、硬度和钙水平每日变化的主要决定因素，同时仍能解析流域开发对水质的高度显著影响。近几十年来，斯库尔基尔河溶质传输的增加似乎是该流域现代郊区发展的直接结果。
