Heavy Metals in Sediments of Inland Water Bodies of India: a Review
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Nature Environment and Pollution Technology ISSN: 0972-6268 Vol. 12 No. 2 pp. 233-242 2013 An International Quarterly Scientific Journal Review Research Paper Heavy Metals in Sediments of Inland Water Bodies of India: A Review Neetu Malik and A. K. Biswas* Environmental Planning and Coordination Organisation, Bhopal, M. P., India *Indian Institute of Soil Science, (ICAR), Bhopal, M. P., India ABSTRACT Nat. Env. & Poll. Tech. Website: www.neptjournal.com In last few decades, due to the rapid increase in the population, industrialization and newer agricultural Received: 27-8-2012 practices, the aquatic resources of India have been deteriorating. The pollution of aquatic ecosystems by Accepted: 17-10-2012 heavy metals is of a great concern due to their persistence, toxicity and accumulative behaviour. The heavy metals can change the trophic status of aquatic ecosystems and make them unsuitable for various purposes. Key Words: They also pose a serious threat to human health. This paper reviews the heavy metal contamination of Heavy metals sediments of Indian inland water bodies. It also discusses the possible sources of pollution. Different standards Inland water bodies for sediment pollution which are in use have also been discussed. It showed that environmental degradation Sediment has become a major societal issue in India due to uncontrolled anthropogenic activities, besides natural Pollution factors. There is an urgent need of creating awareness amongst the public of these problems and find preventive and remedial solutions for management. Expensive high-tech remedial measures are not suitable for the country, and hence emphasis has to be given on prevention. Indigenous research towards mitigation and remediation has to be encouraged, keeping in mind India’s unique problems of poverty, crowding and malnutrition. INTRODUCTION generated per day and only 6 billion liters water (BLW) is collected and treated. While 1,20,000 tonnes of municipal Developing countries of the world are facing pollution prob- solid waste is generated per day, 70% is collected and only lems due to toxic elements in the environment. Among these 5% is treated. These wastes have a huge amount of elements heavy metals are stable and persistent environmen- nonbiodegradable matter including heavy metals which pose tal contaminants (Karadede & Unlu 2007). Some metals like serious threat because of their toxicity, long persistence, Zn, Cu, Fe and Mn, are required for biological functioning bioaccumulation and biomagnification (Singh et al. 2007, (Karadede & Unlu 2007) while others like Cd, Cr, Pb and Malik et al. 2010). The aquatic water bodies of India are Hg have no known significant contribution, but may exhibit being lost at a rate of 2-3% every year and about 59% of the extreme toxicity even in trace amounts. These toxic elements major annual environmental costs have also been spent in enter into the environment both as a result of natural proc- aquatic pollution (Brandon & Homman 1995). Urban water esses and as pollutants from human activities. India is one bodies are depleting more than the rural ones due to receiv- of the wettest countries in the world having 1,170 mm aver- ing external pressure from human settlement and adversely age annual rainfall. It has annual precipitation of water (in- affecting nearby aquatic ecosystems. Urbanization has di- 3 cluding snowfall) to the extent of 4000 km , of which 1869 rect negative impact on water bodies (Khan et al. 1988). km3 water on an average is annually available. Ganga- Brahmaputra-Meghna system is the major contributor (60%) Sediment acts as a reservoir for contaminants including of total water resource potential of the country. heavy metals. Because sediments reflect the actual degree of pollution at a given site, metal analysis of sediments can be India’s environment is becoming fragile and environmen- used to identify the sources of trace metal pollution in an tal pollution is one of the undesirable side effects of indus- aquatic environment (Aston & Thornton 1977, Forstner & trialization, urbanization, population growth and uncon- Salomons 1980). According to Luoma (1990), level of heavy scious attitude towards the environment. At present, envi- metal in sediments can be a sensitive indicator of contami- ronmental protection is the main need of the society. Though nants in hydrological systems. The solubility and availabil- industrialization and development in agriculture are neces- ity of heavy metals in sediment is principally controlled by sary to meet the basic requirement of people, at the same pH, concentration and type of ligands, chelating agents, par- time it is necessary to conserve the environment. ticle size and composition of the sediments (Foster & Hunt Domestic and municipal wastes are more responsible to 1975, Throne & Nickless 1981, Sakai et al. 1986, Jain 2004). degrade the quality of aquatic environment. According to Metals can be introduced both in particulate and soluble form Sengupta (2007), in India 29 billion litres of wastewater is and are subject to numerous physical, chemical, hydrologi- 234 Neetu Malik and A.K. Biswas cal and biological processes i.e., adsorption, complexation, der the Environmental (Protection) Rules for discharge into transportation, inactivation and incorporation (da Silva et streams. In Class I cities of India, about 2277 lakh popula- al. 2000). tion lives in 498 cities. They generate about 35558 MLD Metals dissolved in soil solution, surface and interstitial wastewater out of which a very little amount (11553 MLD waters and those adsorbed on the sediment by cation ex- about 32%) is treated (CPCB 2009-10). In Class II towns of change processes are usually readily available to aquatic and India, about 300 lakh population lives in 410 towns. They benthic organisms as well as to plants (Kumar et al. 2011). generate 2696 MLD wastewater but only 234 MLD (8.6%) Metals strongly bound to the sediments and complexes with is treated (CPCB 2009-10). The rest of the wastes are dis- other chemical compounds are of less concern as they are charged into aquatic systems. most likely unavailable to the biota. Sediments accumulate Industrial source: About 57,000 polluting industries of In- metals and affect the near-bottom water layer due to mobili- dia generate about 13,468 MLD of wastewater, out of which zation/immobilization processes (Kumar et al. 2011). Due nearly 60% is treated, which comes from large and medium to differences in chemistry and biochemistry, the fate and industries (Sengupta 2006). Pollution through major and transport of metals are not uniform and varying from one small industries is also a great concern nowadays. The CPCB element to another. Different metals have different has listed the major polluting industries in India as cement bioavailability and toxicity although all forms of a given mills, sugar, thermal power plants, distilleries, fertilizers, oil metal have an equal impact on the environment. refineries, caustic soda production, petrochemicals, zinc smelting, copper smelting, aluminium smelting, sulphuric SOURCES OF POLLUTION acid, integrated iron and steel, pulp and paper, tanneries, Heavy metal pollution arises from natural as well as anthro- pharmaceuticals, dye and dye intermediates and pesticides pogenic sources. Natural sources include seepage from rocks industries. In these, distilleries, textile, engineering and pulp into water, volcanic activity, forest fires, etc. Anthropogenic and paper industries are added impetus effects on aquatic sources mainly include domestic and industrial wastes. Natu- water bodies than others. The main pollution contributing ral sources contribute less pollution while a good amount of metals and their sources are listed in Table 1. toxic elements enter through sewage and industrial wastes. Besides the industrial sources of lead, listed in Table 1, Domestic sources: Discharge of untreated sewage in water lead exposure also occurs through gasoline additives, ceramic is the most important water pollution source in India. Indian glasses, drinking water system, cosmetics, folk remedies, and Planning Commission in its Tenth Plan Document reported battery/plastic recycling industry. Ash dumps from thermal sewage as a highly polluting source contributing to about power plants contain many polluting metals and complexes, 80% of the total water pollution. Out of about 38000 mil- which are carried to nearby water bodies. Volatile complexes lion litre per day of sewage generated, treatment capacity such as those from uranium, enter the atmosphere via chim- exists for only about 12000 million litre per day. Thus, there ney emissions. is a large gap between generation and treatment of wastewater India has 3.2 lakh units of small-scale industries out of in India. Even the treatment capacity existing is also not ef- which many are highly polluting, and the wastewater gen- fectively utilized due to operation and maintenance prob- eration of these small-scale industries is about 40% of the lems. Operation and maintenance of existing plants and sew- major industries (Maria 2003). Engineering sector of these age pumping stations is not satisfactory, as nearly 39% plants industries is the major wastewater contributor, while the are not conforming to the general standards prescribed un- edible oil and vanaspati is the lowest contributor (Table 2). Table 1: Heavy metals and their sources. Metal Industry Chromium (Cr) Mining, industrial coolants, chromium salts manufacturing, leather tanning Lead (Pb) Lead acid batteries,