Indian urban wetland heavy metal

A study of heavy metal contaminants in the urban lakes of India, particularly around Bangalore have revealed that attempts at mitigation meant to remove these pollutants have not so far worked and may not be a long-term remedy for the problem. I’ve provided more detail on the analysis in the Atomic ezine on SpectroscopyNOW this week, but also wanted to provide some additional background for readers and so I had a few questions for Aboud Jumbe of the Department of Environmental Science, at Bangalore University, Jnana Bharathi Campus who works with N. Nandini:

Is this problem of heavy metal contamination killing wildlife?

At the moment, we haven’t come across any in situ analysis that provides us with a documented and a direct impact of heavy metal pollution and wildlife to the point of killing them per se in the urban scenario. However, we do have our own series of studies and related research that show an alarming range of heavy metals concentrations – in the lake bed sediments, in the water, in the fresh water fish, and in the aquatic macrophytes – exceeding established limits or guidelines.

So, there is a serious impact on the ecology?

By correlating these findings against the established probable toxic effect levels or the threshold limits for fresh water aquatic life, or against the established drinking water limits and guidelines for human consumption, livestock consumption, and even in irrigation, we can infer that most of our findings are giving a rising indication that heavy metals have indeed severely impacted the overall health of the ecology in the city’s wetlands causing severe harm on the aquatic life.

Are any particular species being affected most?

We have recorded a number of cases involving sudden mass deaths in the fresh water fish population, or a number of incidents where birds, especially migratory species such as Painted Storks and the Pelicans being found dead on the water. We are also alarmed by the dwindling sightings of indigenous water snakes such as the Green or Brown Keelback. The question at the centre of the debate now is not whether animals are dying because of the impact of polluted wetlands, but on what scale do heavy metals inflict harm on the affected aquatic life?

Is this problem of heavy metal contamination affecting people too?

It is absolutely certain that people are being affected, and in many ways. One has to bear in mind that the health impact on human beings comes from a multitude of pollutants, e.g along with heavy metals contamination we also have bacterial, pharmaceutical, and even organic pollution caused by volatile organic compounds, PCBs, etc that end up in the urban wetlands.

How come?

There is no distinction between Bangalore’s storm water drains and the city’s waste water drainage lines for the accounted portion of the sewage system. But we do know what happens! That the ground water is continually contaminated from along its sub-surface flow channels and down to the aquifers. Metals, being persistent pollutants, are found in an empirical abundance. A recent study of the Bangalore urban ground water samples by the State Government reveal significant levels of heavy metal contamination in downstream samples collected from the neighbourhoods of open and bore wells of a nearby largest industrial zone in the city.

Does this prove that people’s health is directly affected by heavy metal contamination?

Skeptics have often highlighted a lack of systematic evidence or a hot link that connects acute or chronic diseases to heavy metals in the city’s population. Yes, this may be true because Bangalore Hospitals or Medical Facilities/Institutions usually do not share their crucial data with public institutions. This is mainly due to the absence of an appropriate body that could collect, analyze and connect the dots. Nevertheless, we do have primary data based on direct interaction between us and a selected sample of people in the study area that underlines our increasing concerns for the deteriorating state of primary health in these affected localities.

What kind of direct data?

Our questionnaire survey of a sample of 1000 respondents distributed in three different geographic locations of the City (North, Central and South Zones) reveals an indirect statistical linkage between a portion of the respondents whose homes were connected to the ground water sources (in addition to the drinking water connection from the Bangalore Water and Sewerage & Supply Board) and an increase in gastrointestinal problems within a family unit over time.

For example, in the Central Zone of Bangalore City, we found that 24% of respondents had alternative access to drinking water apart from the BWSSB supply line. Specifically, almost 15% had their own bore-wells, more than 2% said they had a hand-pump dug well, 6% had open wells and over 1% said they were hiring water tankers for water supply. An interesting account here comes from the fact that 25% of respondents had gastro-intestinal problems in their family. Similar trends were found in the Bangalore South Zone. About 28% of the respondents complained about the rise in gastro-intestinal cases over time in a region where 24% of the surveyed respondents said that they had alternative and ground water sources for drinking water supply.

So what does this tell us of the ecological conditions of the City’s catchment systems?

You would only understand that when you saw a number of Government noticeboards placed along the banks of many lakes of the city warning citizens of the dangers of swimming and fishing inside these dilapidated wetlands. In some cases, the State Government has totally forbidden people from engaging in any type of fishing in those lakes as they are so severely polluted. A good example is in the lake known as the Yellamallappa Lake in north-eastern Bangalore where there is a pharmaceutical plant and a cement-grade magnesium production factory.

What else have you found in Yellamallappa?

Apart from excessive concentrations of heavy metals, we also found microbial pathogens such as E. coli, klebsiella spp, Salmonella spp, and Shigella spp. This combination is lethal and could cause a health catastrophe, albeit in the long run.

This is nothing new though, right?

The signs were already there when we conducted a survey of fishermen and their families residing along the banks of the Yellamallappa Lake in 2008. The study showed that at least 60% of respondents said that they were now forced to visit a doctor twice a month due to what they called their persistent illnesses. 45% of the respondents said they suffered from known intestinal conditions while 35% said they were often taken ill with diarrhoea. Of these, about 10% respondents said their illnesses caused them to suffer from severe vomiting on some occasions after consuming fish from the lake.

Obviously, it is not easy to determine the exact cause of their illnesses. We found out that over half of the surveyed respondents said that they would only visit a doctor in a hospital only if they fell severely sick; 45% said they would rather refer their cases to local pharmacies for an unauthorized prescription.

Are crops being affected too, leading to indirect health problems?

Other recent studies have already shown the level of heavy metals contamination in food crops and vegetables. Moreover, Bangalore lakes are increasingly being turned into illegal garbage dumps. Solid waste, including abandoned electronic waste, hospital waste, and construction waste from Bangalore’s booming real estate and construction industry which is filling any open space found wanting including wetlands. Bangaloreans are being attacked both from the water through solid waste/e-waste leachate percolating into the subterranean reservoirs and from the air through smog pollution, and most dangerously, bio-aerosols!

Leachate is a big problem?

One of our studies in Somasundarpalya Lake located in Bangalore South within the perimeters of the famous “electronic city” shows just how severe a leachate flow can be once it reaches the deltaic inflows of the lake. A comparative study of electrical conductivity underscores the levels of industrial effluent entering the lake as raw discharge laden with heavy metals ions.

If crops are being affected, the presumably livestock too?

Another immediate risk to people’s health is the grazing of livestock on vegetation lying inside the polluted basins. According to the State Government Statistics of 2007-08, Bangalore Urban is home to 159,208 heads of Cattle, 88,136 heads of sheep, 31,449 heads of Goats. Combining these figures with those of animals transported into the city for immediate meat consumption, many of these animals have to be provided with a grazing space for some time and that is where polluted basins come into the picture. Most Shrub species used as fodder such as Ipomoea spp, Eichornia crassipes, Alternanthera spp., Cyperus spp., Typha spp, etc. and different species of grass within the lakes’ shoreline perimeters are susceptible to heavy metal contamination. Plants with excessively absorbed metals may find their way into the ruminants’ bodies. The risks here can be highlighted when the meat of the affected animals ends up on someone’s table.

What can be done about it?

We have always emphasized a shift in policy and management levels, more so than in actual rejuvenation programs – an increased interaction and co-operation among various agencies (state departments concerned with environment, soil, natural resource management, public interest groups, citizen groups, agriculture, forestry, urban planning and development, research institutions, government, policy makers, etc) to enhance protective and restoration measures for Bangalore City lakes. This interaction, we feel, should include planning, environmental education and economics of urban wetlands, and urban watershed management.

Enactment of guidelines on physical restoration measures must be initiated. Without Government backed guidelines, we cannot move an inch towards a sustainable and real solution. Formation of Lake Management Guidelines, we believe, will also necessitate an immediate need to create a database on the wetland types, morphological, hydrological and biodiversity data, surrounding land use, hydrogeology, surface water quality, and socioeconomic dependence. We must converge here for a holistic, integrated, but also implementable approach.

So, what would you specifically like to see implemented?

We have called for the following:

  1. Declaration of all urban wetlands as Biodiversity Hotspots through a Government Notification.
  2. Rejuvenation of lakes should be done on a case-by-case basis. Not all lakes are alike and so it is wrong to view all lakes through a single lens of destructive engineering techniques.
  3. Before any lake be taken up for rejuvenation, a complete Environmental Assessment (EA) Report of the current Environmental Status of the wetland should be carefully prepared and impact assessment carried out separately from a Detailed Project Report (DPR). The EA report should be produced before the special EIA environmental committee of the Government of Karnataka for analysis of the wetland system for screening, scoping and authorization. Public participation here should be encouraged and mandated before any agency takes up rejuvenation.
  4. Wetlands should be protected from development zones. A buffer zone must be established between the wetlands borderline and a development zone. Even the channels that link up lakes should be protected and shielded from daily discharge of untreated sewage. We have to re-open the books of history for environmental planning and how the past municipal masters used to emphasize on a demarcation of line between a natural heritage zone and a human development rim.
  5. Rejuvenation of lakes is not just an engineering matter but also equally a case of ecological conservation. It is not understood why is it that until today, most of the rejuvenation programs do not take into account the opinions of wetland ecologists. Most of the time, DPRs or the so-called Detailed Project Reports are made and submitted by civil engineers who give little preference to the ecological aspect of a wetland apart for an abstract view only. Here, a question arises: Do we rejuvenate a “Lake” or just a water “Tank”? and what are the priorities? Is it only rain water harvesting, or beatification, or structural reformation? Or also the need to maintain the wetland ecosystem and its existing life forms by maintaining the natural life of both flora and fauna? This is where most cases of remediation go wrong!
  6. Desiltation may be the necessary way of removing contaminated sediments of the lake’s floor. But this method should be applied only in cases where it is deemed very necessary to do that on lakes which are gravely contaminated or ecologically speaking – dead lakes. This is because desiltation contains a grave risk of exacerbating hydrological imbalances between the surface water basin and the ground water table. Sediments on a lake’s floor play an important part as a hydrological filter and valve that manages the local surface and sub-surface water cycle. If this particular sediment layer is disturbed or physically disrupted it can lead to “perforations” – which means that the lake basin will not be able to sustain its original full tank capacity as water will uncontrollably perforate its way directly to the sub-surface layers.

Research Blogging IconAboud S. Jumbe, & N. Nandini (2009). Heavy Metals Analysis and Sediment Quality Values in Urban Lakes American Journal of Environmental Sciences, 5 (6), 678-687

Author: bob投注平台

Award-winning freelance science writer, author of Deceived Wisdom. Sharp-shooting photographer and wannabe rockstar.