Water Pollution and Its Mitigation

Abstract

Water is one of the key components to drive the activities of life. It is not only used for drinking, but also for agriculture, aquaculture, industrial activities, running power plants, manufacturing medicines, etc. However, the release of domestic, agricultural, aquacultural and industrial wastes has deteriorated the quality of water to a great extent leading to several ill effects like health disorder, eutrophication, bioaccumulation, alteration of biotic community, etc. The chapter focuses on both the causes and effects of water pollution. The prevention and control of water pollution has also been discussed with special emphasis on cost-effective biological control.

Appendices

Annexure 8A: Water Quality of the River Ganga in and Around the City of Kolkata During and After Goddess Durga Immersion

8.1.1 Introduction

Durga Puja is one of the most famous festivals celebrated in West Bengal and particularly in Kolkata, for worshipping Goddess Durga during the period of Navaratri. It is celebrated for 10 days. However starting from the sixth day until the ninth day, the pandals (structures where the Goddesses are kept) with grand idols of Goddess Durga are open for the visitors. The tenth day, also known as Dashami, marks the Visarjan (immersion in water) of the idol with grand celebrations and processions. Durga Puja in 2018 started on October 15 and continued till October 19. However, Durga Puja, 2018, celebrations in Kolkata started early, with Durga Mahalaya on October 9 and Visarjan on October 19.

According to the Hindu Mythology, Goddess Durga emerged from the collective energy of all Gods/Goddesses as an embodiment of Shakti or divine feminine power, to destroy demon Mahishasura, who was blessed with the power of not getting defeated by any man or God (Fig. 8.A.1). This powerful form of Goddess Durga is highly revered in the Indian sub-continent, and her return for destroying the evil forces is celebrated with much grandeur and ceremonies.

Fig. 8.A.1

Goddess Durga with ten arms (Dashabhuja)

The 10th day of the Durga Puja festival is called Dashami; it is believed that on this day, Goddess Durga gained victory over the Demon and thus restored the balance on the Earth. It is also known as Vijayadashami. On this day, Goddess Durga is worshipped and offered many things as she is prepared to leave. Highly enthusiastic devotees gather in large numbers to join the procession that carries the Goddess to the ghats (the banks of the River Ganga with bathing facilities and where several religious rituals are performed) to be immersed in water. Women, especially married woman, initiate the procession by first applying red sindoor or vermillion powder on the Goddess and then to each other. In 2018, the date of immersion was October 20.

In this study we made a comparative assessment of the water quality, considering three toxic heavy metals lead, chromium and cadmium leached from idols in six major banks along the stretch of the River Ganga flowing through the mega city of Kolkata during October 10, 2018 (pre-puja/festival period) and October 22, 2018 (post-puja/festival period).

8.1.2 Materials and Methods

8.1.2.1 Site Selection

Six banks or ghats were selected for the present study, which are basically the zones for immersion. Coordinates of all the study sites in the River Ganga are highlighted in Table 8.A.1.

Table 8.A.1 Coordinates of all the selected sites/ghats along the River Ganga

8.1.3 Analysis of Selective Heavy Metals

Surface water samples were collected from all the six ghats during high tide using 10-l Teflon-lined Go-Flo bottles, fitted with Teflon taps and deployed on a rosette or on Kevlar line, with additional surface sampling carried out by hand. Shortly after collection, samples were filtered through nuclepore filters (0.4 μm pore diameter), and aliquots of the filters were acidified with sub-boiling distilled nitric acid to a pH of about 2 and stored in cleaned low-density polyethylene bottles. Dissolved heavy metals were separated and pre-concentrated from the collected water using dithiocarbamate complexation and subsequent extraction into Freon TF, followed by back extraction into HNO₃. Extracts were analysed for Pb, Cr and Cd by atomic absorption spectrophotometer (Perkin Elmer: Model 3030).

8.1.4 Results

The levels of dissolved Pb, Cr and Cd during the pre-immersion and post-immersion phases in the selected sites of the River Ganga are presented in Figs. 8.A.2, 8.A.3 and 8.A.4. The order of dissolved metals in the study area is Pb > Cr > Cd irrespective of time periods and sites.

Fig. 8.A.2

Dissolved Pb concentrations in (ppm) during pre-immersion and post-immersion phases

Fig. 8.A.3

Dissolved Cr concentrations in (ppm) during pre-immersion and post-immersion phases

Fig. 8.A.4

Dissolved Cd concentrations in (ppm) during pre-immersion and post-immersion phases

8.1.5 Discussion

It is clear from the data sets that there has been considerable increase in the levels of dissolved heavy metals after the process of immersion of idols. For Ramkrishna Ghat, the levels of increase of Pb, Cr and Cd are 61%, 17% and 125%, respectively. For Shibpur Ghat, the levels of increase of Pb, Cr and Cd are 74%, 111% and 86%, respectively. For Princep Ghat, the levels of increase of Pb, Cr and Cd are 93%, 169%, and 83% respectively. For Botanical Garden, the levels of increase of Pb, Cr and Cd are 71%, 98% and 70%, respectively. For Babughat, the levels of increase of Pb, Cr and Cd are 107%, 44% and 116%, respectively, and for second Hooghly Bridge, the levels of increase of Pb, Cr and Cd are 27%, 19% and 5%, respectively. The leftover straws and skeletons of the idols are shown in Fig. 8.A.5.

Fig. 8.A.5

Straws and skeletons of idols. (Source: Mitra and Ray Chaudhuri 2017)

ANOVA carried out with the data showed significant variations between two periods (pre-immersion and post-immersion periods) at p < 0.05, but no spatial variation was observed (Tables 8.A.2, 8.A.3 and 8.A.4). This may be attributed to proximity of the sites and regular tidal actions in the study stretch that has spatially homogenized the dissolved heavy metals. However, concern is there on the point of significant variation in water quality between the pre-immersion and post-immersion phases.

Table 8.A.2 ANOVA for Pb in 6 sample sites during pre-immersion and post-immersion

Table 8.A.3 ANOVA for Cr in six sample sites during pre-immersion and post-immersion

Table 8.A.4 ANOVA for Cd in six sample sites during pre-immersion and post-immersion

Lead, a heavy metal that is used in batteries, paints and the oxide, is employed in the production of crystal glass. A higher level of lead results in cognitive impairment in children to peripheral neuropathy in adults.

Intake of chromium in large amounts has severe detrimental health effects like renal, hepatic and gastrointestinal damage.

Cadmium when consumed along with food and water for a longer period of time results in the bioaccumulation in the kidney and liver causing severe damage to these systems.

8.1.6 Way Forward

In India the practice of idol worship is witnessed since ancient times. It has been a tradition to immerse the idols in water bodies after the festival is over. Consequent pollution of such water bodies has been a matter of concern, and there have been public interests and litigations as well. In the present study, also Pb, Cr and Cd increased in the water bodies of six ghats along the stretch of the River Ganga. In this context it is recommended to use traditional clay for idol making rather than baked clay.

Use of painted idols with chemicals should be prohibited as far as possible. In case painted idols are used, water soluble and nontoxic natural dyes may be used. Natural colours used in the food colours and permitted in pharmaceuticals may be preferred. Several dyes can be extracted traditionally from the vegetative and reproductive parts of plants. Red dyes can be sourced from madder, Brazil wood, beetroot, cranberry, safflower and orchid. Orange dye is obtained from the stigmas of the saffron flower. The flowers camomile and milkwort are the sources of yellow colour. The green colour can be obtained from ripe buckthorn berries and ragweed. The blue colour can be sources from wood plant and indigo. It is also recommended that prior to immersion, worship materials like flowers, clothes, decorating materials like paper and plastics should be segregated and collected for recycling or composting.

A revolutionary concept may be a ‘food for thought’ for the policymakers in the domain of immersion of idols. This idea is based on the concept ‘phytoplankton bloom through iron fertilization’. The idols made of iron structures not only can be recycled for making several metallic objects but can also trigger the growth of phytoplankton in the riverine stretch if left for few months in a bounded or closed space. This closed space can be constructed by channelizing the river water in a sloppy area towards the river bank. The phytoplankton being the major food for the fishes and a sink of carbon dioxide would be an innovative spin-off benefit from this festival. Such concept may seem to be highly challenging but if implemented with proper planning may be a footprint for improving fish population and ecological stability of the mighty River Ganga.

Annexure 8B: Bioaccumulation Potential of a Mangrove Associate Species, Porteresia coarctata

The wastes of anthropogenic and industrial origin are of complex characters and have considerable percentage of heavy metals. The heavy metals in the saline water phase generally deposit on the sediment bed or remain in dissolved state in the water column, depending on the nature of the chemical species. Sediments are the heavy metal sinks in the marine environment (Govindaswamy et al. 1997). Knowledge of the distribution and concentration of heavy metals in sediments will help to detect the sources of pollution in the aquatic phase (Wittmann 1981).

Indiscriminate releases of untreated or partially treated wastes without considering the assimilative capacity of the waste receiving waterbody have resulted in pockets of polluted environs with depleted coastal resources, public health risks and loss of biodiversity. Over 300 million people living in the coastal zone of India are considered to generate 1.11 × 10¹⁰ m³ of sewage annually, a considerable fraction; particularly from coastal cities and towns where sewage collection network exists, enters the marine water (Zingde 1999). This is a common scenario in all the maritime states of Indian sub-continent.

The rapid industrialization and urbanization of the city of Kolkata, Howrah and the newly emerging Haldia complex has caused considerable ecological imbalance in the adjacent coastal zone. The Hugli estuary, situated on the western sector of coastal West Bengal, receives drainage from several channels, which have sewage outlets into the estuarine system. The chain of factories and industries situated on the western bank of the Hugli estuary is another prominent cause behind the gradual transformation of this beautiful ecotone into stinking cesspools of the megapolis. The lower part of the estuary has multifarious industries such as paper, textiles, chemicals, pharmaceuticals, plastic, shellac, food, leather, jute, tyres and cycle rim (Mitra et al. 2005; Mitra 1998; UNEP 1982). Deadly effluents from these industries might scratch the magnificent network of life spun over a long evolutionary period of time in this biotope. In addition to these, the mushroom growth of hotels, resorts and a number of unofficial fish landing centres at the Canning are some prominent negative pressures on the ecological status of the area. The sewage released by these units into the bay not only alters the water quality in terms of nutrient load but may also pose considerable impact on the biotic community inhabiting the zone.

With this background, the present programme aimed to evaluate the status of heavy metal levels (Zn, Cu and Pb) in the vegetative parts of saltmarsh grass (Porteresia coarctata) in the selected stations of mangrove dominated Indian Sundarbans. This saltmarsh grass species is endemic to Sundarban region and is regarded as the pioneer species in island formation (Fig. 8.B.1).

Fig. 8.B.1

Porteresia coarctata in front of the matured mangrove trees in Indian Sundarbans

The role of the species in holding the soil particles with long intricate root system is immense to control the erosion of the river banks. The investigation was carried out during 2016–2017 by the present authors in the estuarine zones of Sundarbans at three different stations, namely, Canning, Chotomollakhali and Bali Island with the aim to assess the bioaccumulation pattern of selected heavy metals in the saltmarsh grass inhabiting the intertidal mudflats of the selected stations in Indian Sundarbans.

In P. coarctata samples, the heavy metals varied as per the order Zn > Cu > Pb. This sequence is uniform in all the three selected stations. In the present study, the concentration of Zn ranged from 49.80 (at Bali) to 165.48 (at Canning) during 2016, and in 2017 the concentration ranged from 55.78 (at Bali) to 171.46 (at Canning). Cu ranged from 20.19 (at Bali) to 63.21 (at Canning) in 2016 and 23.74 (at Bali) to 66.36 (at Canning) in 2017. Pb ranged from 2.66 (at Bali) to 19.22 (at Canning) in 2016 and from 4.31 (at Bali) to 21.67 (at Canning) in 2017.

The concentrations of heavy metals in the vegetative parts of P. coarctata for the present study are tabulated in Tables 8.B.1, 8.B.2 and 8.B.3.

Table 8.B.1 Monthly variations of heavy metals in P. coarctata collected from Canning during 2016 and 2017

Table 8.B.2 Monthly variation of heavy metals in P. coarctata collected from Chotomollakhali Island during 2016 and 2017

Table 8.B.3 Monthly variation of heavy metals in P. coarctata collected from Bali Island during 2016 and 2017

P. coarctata (commonly known as saltmarsh grass) is widely distributed in the mudflats of Sundarbans and is a pioneer species in the process of island ecological succession (Jagtap et al. 2006; Mitra 2013). It is a tetraploid (2n = 48) species producing highly recalcitrant seeds (Probert and Longley 1989) and occurs all over the tropics as a mangrove associate, where the soil is inundated (twice a day) with saline river or seawater of 20–40%_o. The species can also withstand submergence with saline water for a long period of time due its inherent capacity to tolerate high levels of salinity and submergence (Flowers et al. 1990). The root system of Porteresia is well adapted to cope with increasing salinity leading to decreased water transport. To overcome intertidal strong flow, it often forms pseudo-taproots up to a depth of 1 m and fibrous roots develop from the tip of those pseudo-taproots and internodes of a wide-spreading underground stem called a ‘sobole’ (Latha et al. 2004). It is reported by some authors that saltmarsh genesis is based on accretion due to sedimentation of suspended matter, supplied by tidal water or flood water of marine and riverine origin.

It is reported by some researchers that the coastal zones and estuaries, which are the primary habitat of this species, are exposed to effluents from chemical industries every day. As a consequence nutrients and contaminants like heavy metals, pesticides and halogenated hydrocarbons are transported into the saltmarsh sediments since they are partly bound to suspended particles. Urban saltmarshes often receive large pollutant loads, including discharges of heavy metals from industry and transportation activities. In Porteresia bed, water soluble metals and exchangeable metals are the most available and precipitated inorganic compounds; metal complexes with large molecular weight, humus materials and metals adsorbed to hydrous oxides are also possibly available. P. coarctata, being an endemic species of Sundarbans region, is exposed to heavy metal pollution, as the region is contaminated with conservative pollutants (Mitra 1998; Mitra et al. 2011).

Marsh plants are known to absorb and accumulate metals from contaminated sediment (Giblin et al. 1980; Kraus et al. 1986; Kraus 1988; Sanders and Osman 1985). The absorption of contaminants is one reason that wetlands are being used for wastewater treatment. Metals taken up by plants are also capable of re-entering marsh systems through excretion from leaf salt glands (Kraus et al. 1986; Kraus 1988). Metals present within the water column of the plant may be carried through open stoma. This could result in the adhesion of the metals to the outer surface of the leaf. The present study is extremely important for two specific reasons:

• 1. The saltmarsh grass species P. coarctata can act as an agent of bioremediation and can be utilized by coastal industries to biologically treat the effluents contaminated with heavy metals (with a specific retention time, which has not been studied in the present programme).

• 2. In the mudflats of Sundarbans, cattle from the adjacent island villages graze on P. coarctata. Hence, marsh grass contaminated with heavy metals may accumulate in the body tissues of cattle, which may be further transferred to human beings through their milk and meat.

Implementation of water pollution prevention strategies and restoration of ecological systems are integral components of all development plans. To preserve our water and environment, we need to make systematic changes in the way we grow our food, manufacture our goods and dispose of the wastes (Lazaroff 2000). In India, agriculture is the biggest user and polluter of water. If pollution by agriculture is reduced, it would improve water quality and would also eliminate cost incurred for treatment of diseases. Like all other inputs, there is an optimal quantity of fertilizer for given conditions, and excess application does not improve the crop yield. Pricing of fertilizers and pesticides as well as appropriate legislation to regulate their use will also go a long way in stopping indiscriminate use. Industries need to carefully treat their waste discharges. Manufactures may reduce water pollution by reusing materials and chemicals and switching over to less toxic alternatives. Industrial symbiosis, in which the unusable wastes from one product/firm become the input for another, is an attractive solution. Also there is a need to encourage reductions or replacement of toxic chemicals, possibly through fiscal measures. Pollution taxes in the Netherlands, for example, have helped the country slash discharges of heavy metals such as mercury and arsenic into waterways by up to 99% between 1976 and the mid-1990s.

Environmental improvement and restoration should be planned and implemented such that the freshwater and groundwater resources are protected and their quality is maintained and/or enhanced. On the legislative front, laws are required to check littering as well as to implement ‘polluter pays’ principle. More importantly, these laws should be strictly enforced.

For making the people of various sections of our society aware about the different issues of water resources management, a participatory approach may be adopted. Mass communication programs may be launched using the modern communication means for educating the people (preferably the island dwellers of Sundarbans) about water pollution. Capacity building should be perceived as the process whereby a community equips itself to become an active and well-informed partner in decision-making. The process of capacity building must be aimed at both increasing access to water resources and changing the power relationships between stakeholders. Capacity building not only is limited to officials and technicians but must also include the general awareness of the local population regarding their responsibilities in sustainable management of the water resources. Policy decisions in any water resources projects should be directed to improve knowledge, attitude and practices about the linkages between health and hygiene, provide higher water supply service levels and improve environment through safe disposal of human wastes. Sustainable management of water requires decentralized decisions by giving authority, responsibility and financial support to communities to manage their natural resources and thereby protect the environment. Approaches to water pollution control that focuses on wastewater minimization, in-plant refinement of raw materials and production processes, recycling of waste products, etc., should be given priority over traditional end-of-pipe treatments. An important element in water pollution control strategy is the formulation of realistic standards and regulations. However, the standards must be achievable and the regulations enforceable.