The use of treated wastewater (TWW) has gained recognition as an alternative source for freshwater irrigation, and is steadily expanding worldwide. Despite the benefits of freshwater conservation and nutrient richness, there is mounting evidence of TWW adverse effects on soil, yield, and the environment. Irrigation using TWW has resulted in soil water repellency, in which preferential flow pathways and uneven soil water and chemical distribution occur. These increase deep water percolation and chemical leaching, which can lead to soil and groundwater pollution. This study was conducted in a commercial citrus orchard grown on sandy-loam soil in central Israel and irrigated with TWW, with the aim of investigating the remediation of these adverse effects, by repeatedly spraying a nonionic surfactant on the soil surface. The surfactant application succeeded to turn the soil wettable, diminishing the preferential flow pathways, and rendering the soil water and dissolved chemicals uniformly distributed. The overall water content in the 0–40 cm layer increased, and deep percolation and chemical leaching substantially decreased. The grapefruit yield increase during the two-year study period increased the water use efficiency. Electrical resistance tomography scans executed during and after irrigation events for two subsequent years revealed that a “soil memory” phenomenon has been developed for water repellent soils, where water flow takes place through previously developed preferential flow pathways in such soils. This study demonstrates that recurrent surfactant application enables a continuous use of TWW, while eliminating most of its prejudicial effects.

中文翻译：

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通过重复表面表面活性剂应用修复处理过的废水灌溉的不利影响

使用处理过的废水 (TWW) 作为淡水灌溉的替代来源已获得认可，并且正在全球范围内稳步扩大。尽管淡水保护和营养丰富有好处，但越来越多的证据表明 TWW 对土壤、产量和环境产生不利影响。使用 TWW 灌溉导致土壤拒水性，其中出现优先流动路径和不均匀的土壤水和化学物质分布。这些会增加深水渗透和化学浸出，从而导致土壤和地下水污染。本研究在以色列中部沙壤土上种植并用 TWW 灌溉的商业柑橘园进行，目的是通过在土壤表面反复喷洒非离子表面活性剂来研究这些不利影响的修复。表面活性剂的应用成功地使土壤变得可湿，减少了优先流动路径，并使土壤水和溶解的化学物质均匀分布。0-40 cm 层的总含水量增加，深层渗透和化学浸出显着减少。两年研究期间葡萄柚产量的增加提高了水分利用效率。在随后两年的灌溉事件期间和之后执行的电阻断层扫描显示，防水土壤已经形成了“土壤记忆”现象，其中水流通过先前在此类土壤中形成的优先流动路径发生。这项研究表明，经常使用表面活性剂可以连续使用 TWW，同时消除其大部分不利影响。