Wastewater Irrigation and Heavy Metal Contamination in Peri-Urban India
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Wastewater irrigation and heavy metal contamination in peri-urban india F. Marshall1, R. Sharma,2 M. Agrawal, 2 D S Bhupal, 3 C. Ghose,1 R Agarwal4 1. University of Sussex, Brighton, UK; 2. Banaras Hindu University, Varanasi, India; 3. Delhi University, Delhi, India; ToxicsLink, New Delhi, India. Project background Study sites One of the threats to food quality and safety in the peri-urban areas in developing countries are heavy metals in industrial effluents, and from sewage The city of Varansi was chosen as the project site since it is an advanced agricultural as well as industrial center. The main industries are engaged in manufacturing of metal products, plants. Dietary intake of heavy metals can pose a substantial risk to the health of families who depend upon the use of contaminated irrigation water chemicals, electrical apparatus and textiles, dyeing and printing units. Initial selection of case studies areas in urban and peri-urban Varanasi focusedon three areas: to grow crops to meet their food requirements. Dinapur - in the vicinity of the city's major sewage treatment works; Shivpur - to the north west of the city close to Shivpur industrial area; and, Despite environmental protection legislation, and monitoring and control bodies being in existence in India, industries Lohta - to the west of the city close to several industrial areas (which often cluster in peri-urban areas) are a main source of water pollution. Industries often cluster in peri-urban areas, Varanasi District Land Use Map where agricultural land use is dominant and farmers have little option other than to use this untreated or inadequately Jammu & Kashmir 0 10 20 treated water for irrigation of food crops. Wastewater irrigation and the land application of sewage treatment residues km Rive are traditional practices around the world. An estimated 80 per cent of wastewater in developing countries may be used Himachal Wheat - Rice - Millet Wheat - Rice - Pradesh Pulses r Go Wheat - Rice - mati for irrigation and cities in India are no exception to this. Punjab Uttar- Pulses anchal Haryana Delhi Sikkim Arunachalh There are reports of some farmers proactively using untreated waste water and sludge because of its levels of nitrogen, des Nani Nala (drain) Uttar Pra Rajasthan Pradesh phosphorus and potassium, positively influencing crop productivity. This project assesses the links between the use of Assam Wheat - Rice - Millet Bihar Nagaland Shivpur contaminated irrigation water and heavy metal concentrations in food crops important to the poor. Through the Varanasi Meghalaya Manipur participation of local communities and authorities it assesses appropriate technical and institutional approaches to Riv Jharkhand Tripura er V Gujarat West aruna Madhya Pradesh address the issue. Bengal Mizoram Kotwa Dinapur LohtaWheat - Rice - sgarh ati Pulses North Chh Orissa The project team consists of an interdisciplinary group of researchers working across the natural and social sciences and in the policy advocacy arena. Maharashtra Mughalsarai The team has been working together to assess the nature and extent of emerging environmental threats to the livelihoods of the poor in India and to Gangapur explore technical and institutional means of addressing them. It combines empirical studies to assess the extent of contamination through the food Wheat - Rice - Pulses Andhra chain, who is affected and how it might be controlled, with attempts to understand and mobilise the policy processes that can lead to safer food for the Pradesh Goa River Ganga urban and peri-urban poor. CROPS: Wheat, Brinjal, Tomato, Spinach, Amaranthus, Okra, Cauliflower, Cabbage, Radish Karnataka Urban Area Mainly Unirrigated Land Arable Land Water Body Ker Tamil Nadu Rural Habitat Garden and Orchard ala Note: Map not to scale Source: Department of Geography Road Study Site HEAVY METALS: Cadmium, Chromium, Copper, Lead, Banaras Hindu University Manganese, Nickel, Zinc. Adapted by SPRU, University of Sussex, 2006 Key outputs 3. Development of / improved awareness of appropriate technical methods of monitoring heavy metal contamination in 1. Extent of heavy metal contamination in irrigation water, soil and crops. 2. Relationships between heavy metal contamination in irrigation water and irrigation water. accumulation of damaging levels in the edible portion of crops. The project is working with local stakeholders to investigate the possibilities for the introduction of appropriate low-cost The project monitored heavy metal contamination in wastewater used for irrigation of food crops by the urban and peri-urban poor. monitoring techniques, in the case study areas, and to promote increase awareness of monitoring options as appropriate. Pollution sources were identified and seasonal trends recorded. Monthly samples of water, soil and nine vegetables were collected • Wastewater used for irrigation at both Dinapur and Lohta has significantly over a period of 12 months (up to August 2004). On each sampling occasion three replicate samples were selected at up to five sub- higher levels of contamination with heavy metals compared to ‘clean’ water 4. Improved health awareness amongst health professionals and the public at risk of both consuming contaminated crops. sites in each of the three case study areas (figure 1). Samples were washed to remove contamination due to aerial deposition. sourced from local tube wells (figure 2). The project is exploring ways in which the medical profession, public health officers, farmers and the general public can • Heavy metal contamination of crops was significantly higher at sites at which be informed about the risks associated with wastewater irrigation and will assess means of supporting policy Key Findings: Cadmium, chromium, manganese and nickel found to exceed FAO standards for irrigation water quality. Cadmium, farmers have been using wastewater irrigation as compared so those that use development in this area. zinc, chromium and copper were found to exceed the European Union (EU) standard for soil. Cadmium, lead and zinc were ‘clean’ water. found in exceedence of EU and UK standards for food quality. Further analysis of the results indicates that irrigation by • Controlled experimental studies confirmed the link between contaminated wastewater at the study sites increased the heavy metal concentration of soils and plants in the receiving area. Cd and Pb were wastewater and contamination in crops. 5. Policy mapping and intervention of greatest concern, due to the high levels found in plant material and the high degree of toxicity. • The phytoavailability of heavy metals in soil was significantly greater in areas The findings highlight the need for greater cross-sectoral and disciplinary coordination to understand the links between where wastewater was used for irrigation (figure 3). environmenal pollution & food safety and to address the issues that arise in the context of the livelihoods of the poor. Heavy metal contamination in crop tissue were frequently found to exceed permissible limits in areas where measured levels of The project identifies appropriate drivers for policy change and institutional pathways by which the problems associated contamination in the irrigation water did not exceed permissible limits. The water chemistry has an important role to play in A range of agricultural measures for ameliorating the impact of using contaminated with farming in peri-urban areas can be addressed. determining the extent to which particular heavy metals are released from sediment into the water column. This has important wastewater is being investigated. FOOD SAFETY implications for policies and programmes aimed at reducing contamination in crops, in that monitoring of water quality alone is not POLICY adequate. Fig 3: Mean Phytoavailable Cadmium Concentration in Soil at Dinapur, HEALTH & NUTRITION POLICY 3.53.5 Varanasi ENVIRONMENT Fig 1: Mean concentration of cadmium in water, soil and Spinach at three study villages in Varanasi, India Fig 2: Mean Cadmium Concentration in Spinach Contaminated POLICY crop at Varanasi, India 3.03.0 Consumers Soil 8 Industrial (urban & rural) Water Spinach me Dinapur Lohta 0.050.05 2.52.5 il pollution 3.53.5 7 3.53.5 so Peri-urban agriculture 3.03.0 6 2.02.0 0.040.04 3.03.0 Industries Top 2.52.5 5 Sub-soil 2.52.5 1.51.5 0.030.03 4 Contaminated 2.02.0 2.02.0 soil mme per gram URBAN Livelihood 1.51.5 3 1.01.0 PLANNING AGRICULTURAL 0.020.02 1.51.5 Wastewater POLICY (Industrial & Municipal) 1.01.0 1.01.0 rogra 2 0.50.5 Urban 0.010.01 1 Sub-soil 0.50.5 0.50.5 mic soil Top areas Agricultural 0.00.0 IRRIGATION practices Concentration (mg/l) Concentration (mg/kg) 0.00.0 0 0.000.00 Concentration (mg/kg) 0.00.0 wastewater clean water wastewater clean water MANAGEMENT Farmers DinapurDinapur LohtaLohta ShivpurShivpur DinapurDinapur LohtaLohta ShivpurShivpur DinapurDinapur ShivpurShivpur LohtaLohta Soil irrigated with clean water European Union standard for cadmium in leafy vegetables Soil irrigated with wastewater WATER POLICY European Union standard for FAO standard for cadmium European Union standard for cadmium in soil in irrigation water cadmium in leafy vegetable European Union standard for cadmium in soil This publication is an output from a research projects funded by the United Kingdom Department for International Development (DFID) for the benefit of developing countries. The views expressed are not necessarily those of DFID (R8160 Enkar) For further information contact Dr Fiona Marshall, SPRU, The Freeman Centre, University of Sussex, Brighton, BN1 9QE. Email [email protected]; Tel: +44 (0)1273 877130. Visit project website: http://www.pollutionandfood.net 5.