RESEARCH ARTICLES CURRENT SCIENCE, VOL. 114, NO. 1, 10 JANUARY 2018 166 *For correspondence. (e-mail: rashmimakkarpanwar@gmail.com) Assessment of contamination of soil and groundwater due to e-waste handling Rashmi Makkar Panwar* and Sirajuddin Ahmed Department of Civil Engineering, Jamia Millia Islamia, New Delhi 110 025, India This paper reveals the magnitude of heavy metal con- tamination of soil and groundwater in and around an unauthorized e-waste recycling site in Delhi. Though unsafe and unorganized and with the e-waste handling now legally banned in Delhi, the informal sector is still actively involved in dismantling, extracting and dis- posing of e-waste in certain places on a considerably large scale. The leachate produced by these recycling units contains a large amount of heavy metals which are likely to pollute the groundwater and soil adjoining the recycling sites. This study evaluates the e-waste contamination at such sites by monitoring the poten- tial contaminants at a number of specific monitoring points in Krishna Vihar near Mandoli. The soil and underground water samples are tested for the pres- ence of heavy metals around e-waste recycling and dumping sites using atomic absorption spectrometry. The standard values according to Central Ground Water Board are taken as reference values for water, and standards for agricultural soil in Britain as refer- ence values for soil. The results show that the groundwater and soil in and around these sites have been contaminated by lead, copper, chromium and cadmium to a large extent. Keywords: Contamination, e-waste, groundwater, heavy metals, soil. THE remarkable growth in information technology and constant increase in use of electronic gadgets in our daily life over the past ten years has resulted in large quantity of electronic waste (e-waste). The waste electrical and electronic equipment (WEEEs) contain several sub- stances, many of which are toxic in nature and could be hazardous for the environment, specially soil and water. e-Waste is one of the major upcoming pollution problems for the entire world because of a variety of toxic sub- stances present in it which if not disposed according to the protocols 1 cause contamination of environment and affect human health. The retrieving of valuable and base metals is possible by recycling e-waste. However, high labour cost and the strict environmental legislation in developed countries have consolidated these activities mostly in Asian countries such as China and India 2 . If we consider the Indian scenario an increase of about 62% in total e-waste generation in a span of 6 years has been witnessed 3 . Along with other conventional waste, e-waste is considered to be a cause for serious concern in munici- pal solid waste management 4 . While recycling in auto- matic methods, precious metals are lost in the bulk of other less valuable materials 5 . The possibility of profit making makes the informal recycling of e-waste an attractive business making people interested in it. As a number of materials are involved in electrical and elec- tronic equipment manufacturing, recycling of end-of-life products is very complicated 6 . Metals with a density higher than 5 or 6 g/cc, and atomic number more than 20, that is beyond calcium in the periodic table are known as heavy metals 7 . When e-waste is irresponsibly dumped, it can adversely affect fertility of soil. It can also render water unfit for con- sumption as heavy metals leach into soil and water 8 . High concentrations of heavy metals negatively affect soil microbial population, which in turn adversely affects soil fertility 9 . Heavy metals are released while recovering useful material and from open burning of residue and remains of e-waste. This pollutes the air, soil and water. Heavy metals thus released into the soil are taken up by plants through their roots which are ultimately accumu- lated in human tissues 10 . Bioaccumulation of heavy metals is proven by increased levels of Zn, Cu, Fe, Mn, Ni, Cd and Pb in spinach due to sludge application 11 . Studies have shown that treated and untreated wastewater if used for irrigation can cause accumulation of Cd, Pb in the edible portions of vegetables which cause health issues if consumed for a long duration 12 . It is also a must to evaluate the distribution of heavy metals based on their ion solubility to conclude the effect of potentially toxic elements 13 . The unrecovered heavy metals and residual auxiliary substances like mercury and cyanide can leach through the soil and form inorganic and organic com- plexes within soils 14 . Meaningful risk assessment of metal- contaminated soils cannot be done only on the basis of total heavy metal content present, because the correlation between mobile fraction of metal to total metal is gener- ally poor 15 . Mass distribution of different elements be- tween dissolved, adsorbed and various solid phases can be predicted by Visual MINTEQ method. This method is used to model solubility data which has illustrated diverse dissolution/precipitation dynamics of calcium, copper, zinc and lead in solid waste in Guwahati and