Quality of rivers of the United States, 1975 water year; based on the National Stream Quality Accounting Network (NASQAN)
Quality of rivers of the United States, 1975 water year; based on the National Stream Quality Accounting Network (NASQAN)
复制标题
美国河流质量，1975年水年；
DOI：
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发表时间：
1977
期刊：
影响因子：
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通讯作者：
J. Ficke
中科院分区：
文献类型：
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作者：
J. C. Briggs;J. Ficke
国家河流质量核算网络(NASQAN)是由美国地质调查局建立的，旨在为持续评估美国河流的质量提供全国统一的基础。测站一般位于水文核算单位的下游端，以测量从单位流出的水量和水质。1976年水年是该网络运行的第二年，它基本上代表了所有的核算单位，从而描述了整个国家的水质。1976年水年期间，有345个站点测量的大量水质成分的数据。NASQAN站的温度数据(通常是连续测量或每日测量)被拟合为一阶调和方程，并报告了每个站的调和函数参数。美国北部、夏威夷和波多黎各的平均气温一般在5摄氏度-10摄氏度到20摄氏度以上；62个测站的平均气温低于10摄氏度，只有7个测站的平均气温高于24摄氏度。温度曲线的幅度在中纬度和大、中原地区最大(大于12°C)，而在亚热带和冷气候地区最小。考虑到NASQAN数据所描述的美国河流的化学和生物特征，东北部、东南部和西北部的水质(以许多标准衡量)是最好的。这些水域通常含有较低的溶解固体和少量化学成分，通常较软(佛罗里达州除外)，并携带相对较少的悬浮泥沙。这些情况主要反映了该地区的地质情况和较大的降水量。然而，其中许多水域显示出污染的影响，携带中等或高浓度的营养物质，并相应地具有较高的附生植物和漂浮植物种群。指示性细菌的高数量也显示出局部污染的迹象，特别是在人口或动物数量较多或两者兼而有之的地区。与该国其他地区相比，中大陆地区的河流通常含有更高浓度的次要元素。中大陆和西南部地区的大多数河流反映了干旱或半干旱的气候、易侵蚀的土壤和农业活动。它们的特点是溶解的主要和次要成分、悬浮沉积物、主要营养物质和生物群(漂浮和附着的水生植物和指示细菌)水平中等到高度。此外，在这些地区的溪水和底泥中发现的农药残留最多，浓度最高。
The National Stream Quality Accounting Network (NASQAN) was established by the U.S. Geological Survey to provide a nationally uniform basis for continuously assessing the quality of United States rivers. Stations are generally at the downstream end of hydrologic accounting units in order to measure the quantity and quality of water flowing from the units. The 1976 water year is the second year of operation of the network that represents essentially all of the accounting units and thereby describes the water-quality of the entire country. Data are available on a large number of water-quality constituents measured at 345 stations during the 1976 water year. Temperature data (usually continuous or daily measurements) from NASQAN stations were fitted to a first order harmonic equation, and the parameters for the harmonic function are reported for each station. Mean temperatures generally range from 5°-10°C in the North to more than 20°C along the southern border of the continental United States, in Hawaii, and in Puerto Rico; mean temperatures were less than 10°C at 62 stations and greater than 24°C at only 7 stations. Amplitudes of the temperature curves are greatest (greater than 12°C) for the streams at midlatitudes and in the Great and Central Plains, and are smallest for the subtropical and cold-climate streams. Considering chemical and biological characteristics of United States streams as described by NASQAN data, water quality is best (by many standards) in the Northeast, Southeast, and Northwest. These waters are generally low in dissolved solids and minor chemical constituents, are generally soft (except in Florida), and carry relatively small amounts of suspended sediment. These conditions mainly reflect the geology of the areas and the relatively large amounts of precipitation. However, many of these waters show the effects of pollution and carry moderate or high concentrations of nutrients and have correspondingly high populations of attached and floating plants. High counts of indicator bacteria also show signs of local pollution, particularly in areas of the country with large human or animal populations or both. Streams in the mid-continent area generally contain higher concentrations of minor elements than other areas of the country. Most streams in the Midcontinent and Southwest areas reflect the arid or semiarid climate, erodible soils, and agricultural activities. They are characterized by moderate to high levels of dissolved major and minor constituents, suspended sediment, major nutrients, and biota (floating and attached aquatic plants and indicator bacteria). In addition, pesticide residues were found most often and concentrations were highest in stream water and bottom sediments found in these areas.