Abstract
Background.Industries such as electroplating, mining and battery production are major sources of heavy metal-rich waste entering nearby water bodies. Irrigation with heavy metal contaminated water can deteriorate soil quality as well as agricultural produce and have further toxic effects on human health.Objectives.The objective of the present study was to estimate the concentration of hazardous heavy metals such as chromium (Cr), cadmium (Cd), copper (Cu), nickel (Ni), zinc (Zn) and lead (Pb), as well as physico-chemical variables (pH, electrical conductivity, total dissolved solids, chemical oxygen demand and dissolved oxygen) at sampling locations along the Najafgarh and Loha mandi drains in Delhi, National Capital Region, India.Methods.The present study evaluated the quality of wastewater from the Najafgarh and Loha mandi drains, which are used for irrigational purposes in the Delhi region. Drain water quality was monitored for a period of 2 years for physico-chemical variables (pH, chemical oxygen demand, electrical conductivity and dissolved oxygen) as well as heavy metal concentrations (Cr, Cu, Cd, Zn, Ni and Pb). The two-year monitoring period (July 2012–March 2014) was chosen to represent three seasons: pre-monsoon, monsoon, and post-monsoon.Results.Varied concentrations of multiple heavy metals were found due to the extensive discharge of untreated industrial effluents into the drain water. Punjabi Bagh of Najafgarh drain was the most contaminated sampling site with the maximum concentration of Zn (12.040 ± 0.361 mg L−1), followed by Cr (2.436 ± 0.073mg L−1) and Cu (2.617 ± 0.078 mg L−1).Conclusions.Consumption of heavy metal-contaminated agricultural products can cause deleterious human health effects, leading to further health problems. The presence of multi-heavy metal ions above the Food and Agriculture Organization of the United Nations (FAO) permissible limits indicated that drain water was not suitable for irrigational purposes, and adequate measures are required to remove the heavy metal load from drain water.Competing Interests.The authors declare no competing financial interests.
Highlights
The agriculture sector accounts for more than 70% of global water usage.[1]
The optimum range of pH according to the FAO standards for irrigation is 6.5-8.4.22 The pH values (7.32-7.60) were slightly alkaline at an average temperature of 27°C
Values for total dissolved solids at the various sampling sites of the Najafgarh drain ranged on the lower side (249357 mg L-1) at an average temperature of 27°C
Summary
The agriculture sector accounts for more than 70% of global water usage.[1] the increasing demand for water from the energy and municipal industries in peri-urban and urban areas decreases the availability of fresh groundwater for agriculture.[2,3,4,5] A survey across different government agencies predicted a large increase in water demand by 2050 (in total 1447 km3) by each sector, with the agricultural sector continuing to demonstrate the highest demand compared to other sectors.[6] At the same time, inequality in supply and demand is projected due to multiple factors such as population explosion, urbanization and Industries such as electroplating, mining and battery production are major sources of heavy metal-rich waste entering nearby water bodies. The objective of the present study was to estimate the concentration of hazardous heavy metals such as chromium (Cr), cadmium (Cd), copper (Cu), nickel (Ni), zinc (Zn) and lead (Pb), as well as physico-chemical variables (pH, electrical conductivity, total dissolved solids, chemical oxygen demand and dissolved oxygen) at sampling locations along the Najafgarh and Loha mandi drains in Delhi, National Capital Region, India. The use of municipal and industrial wastewater for irrigation whether untreated or treated, has been widely practiced in urban and peri-urban areas in India and many other countries.[11,12] Studies have reported the presence of beneficial nutrients in wastewater, but the volume of available wastewater is very low.[12,13] The biggest challenge in using wastewater for irrigation is that along with beneficial nutrients, crops are exposed to toxic contaminants.[7,14] The occurrence
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