USDA-ARS, US Arid-Land Agricultural Research Center, Maricopa, AZ 85138, USA.
Environ Monit Assess. 2012 Mar;184(3):1559-72. doi: 10.1007/s10661-011-2060-4. Epub 2011 May 21.
To assess the potential for treated wastewater irrigation to impact levels of fecal indicator bacteria (FIB) and salinity in irrigated soils, levels of Escherichia coli, Enterococcus, and environmental covariates were measured in a treated wastewater holding pond (irrigation source water), water leaving the irrigation system, and in irrigated soils over 2 years in a municipal parkland in Arizona. Higher E. coli levels were measured in the pond in winter (56 CFU 100 mL(-1)) than in summer (17 CFU 100 mL(-1)); however, in the irrigation system, levels of FIB decreased from summer (26 CFU 100 mL(-1)) to winter (4 CFU 100 mL(-1)), possibly related to low winter water use and corresponding death of residual bacteria within the system. For over 2 years, no increase in FIB was found in irrigated soils, though highest E. coli levels (700 CFU g(-1) soil) were measured in deeper (20-25 cm) soils during summer. Measurements of water inputs vs. potential evapotranspiration indicate that irrigation levels may have been sufficient to generate bacterial percolation to deeper soil layers during summer. No overall increase in soil salinity resulting from treated wastewater irrigation was detected, but distinct seasonal peaks as high as 4 ds m(-1) occurred during both summers. The peaks significantly declined in winter when surface ET abated and more favorable water balances could be maintained. Monitoring of seasonal shifts in irrigation water quality and/or factors correlated with increases and decreases in FIB will aid in identification of any public health or environmental risks that could arise from the use of treated wastewater for irrigation.
为了评估处理后的废水灌溉对灌溉土壤中粪便指示菌（FIB）和盐分水平的潜在影响，在亚利桑那州一个市政公园的 2 年时间里，对处理后的废水蓄池塘（灌溉水源）、离开灌溉系统的水以及灌溉土壤中的大肠杆菌、肠球菌和环境变量进行了测量。冬季池塘中大肠杆菌水平较高（56 CFU 100 mL(-1)），夏季较低（17 CFU 100 mL(-1)）；然而，在灌溉系统中，FIB 水平从夏季（26 CFU 100 mL(-1)）降至冬季（4 CFU 100 mL(-1)），这可能与冬季用水量低和系统内残留细菌相应死亡有关。2 年多来，灌溉土壤中没有发现 FIB 增加，尽管在夏季最深（20-25 厘米）土壤中测量到最高的大肠杆菌水平（700 CFU g(-1)土壤）。水输入与潜在蒸散量的测量表明，在夏季，灌溉水平可能足以使细菌渗透到更深的土壤层。未检测到因处理后的废水灌溉而导致的土壤盐分总体增加，但在两个夏季均出现高达 4 ds m(-1)的明显季节性峰值。当表面蒸散量减少且可以维持更有利的水量平衡时，冬季峰值显著下降。监测灌溉水质的季节性变化和/或与 FIB 增加和减少相关的因素，将有助于确定因使用处理后的废水进行灌溉而可能产生的任何公共卫生或环境风险。
