Abstract
There is consensus on the impact of wastewater irrigation on soil properties and heavy metal accumulation. The studies that show the impact of temporal changes as a result of different long-term additions of wastewater on the heavy metal accumulation and degradation of soil are extremely limited. This study was carried out to assess heavy metal contamination in soils irrigated with wastewater for more than 30 years in Egypt. A total number of 12 irrigation water samples and 12 soil profiles were collected during 2020 and were chemically characterized. The results showed that soils irrigated with wastewater over the long term contained significantly higher concentrations of heavy metals compared to fields irrigated with fresh water. Heavy metal levels in water and soil samples were within the permissible limits, with the exception of Cd concentration in water (0.03 mg L−1). Continuous cultivation for a long period of time (30 years) using raw urban wastewater application has led to the adverse effect of increasingly available Pb concentration (5.44 mg kg−1). Similar temporal behavior was seen for Cd and Fe, which increased by 0.98 and 11.2 mg kg−1, respectively, after 30 years. The heavy metals in wastewater-irrigated soils significantly increased in clayey soils, as compared to sandy soils irrigated from the same source. Our findings provide important information for decision makers in Egypt and similar countries for the development of a strategy for the use of wastewater in irrigation for sustainable agricultural management.
Highlights
In the most arid and semiarid regions of the world, water security is considered to be one of the main problems on the path to sustainable agriculture, due to water restrictions and increased water consumption [1,2]
Compared to the FAO limits (
Sodium adsorption ratio (SAR) values were 5.0, 7.1, and 12.9 for Source 1 (S1), S2, and S3 sources, respectively. These values are higher than FAO safe limits (3.0), owing the wastewater quality generated by agricultural effluents and raw urban sources
Summary
In the most arid and semiarid regions of the world, water security is considered to be one of the main problems on the path to sustainable agriculture, due to water restrictions and increased water consumption [1,2]. This research has studied the effects of reuse on soil, plants, crops, water, and public health, as well as the economic viability of this method. Ibekwe et al [14] proposed using treated wastewater effluent for irrigation in agriculture as an alternative water source because of the increasing scarcity of fresh water in arid and semiarid regions of the world. Bedbabis et al [15] suggested the reuse of treated wastewater in agricultural applications in Tunisia as a sustainable solution to water scarcity. The authors conducted their research in an olive orchard planted on sandy soil and subjected to irrigation treatments and observed a significant decrease of pH and a significant increase of OM, SAR, and EC in the soil
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