Even if there is no emission of persistent organic pollutants in a region, these areas can still be affected by exposure to these pollutants transported from hundreds of kilometre away
Water and air pollution seriously impact the health of human and the ecosystem, with a rapidly growing, resource-consuming population. Less than 1 per cent of world’s freshwater is available for human consumption, and everyday, over 2 million tonnes of sewage, industrial and agricultural wastes are released into waters around the world.
Riverine pollution is caused by numerous factors, but the biggest determining factor continues to be development in areas vulnerable to run-off. The anthropogenic activity follows a template of resource consumption, utilisation, and wastage. Applied to the context of freshwater from rivers, we consume water from our rivers, use it for our needs and dispose downstream for another set of users.
Unplanned and uncontrolled disposal of solid waste, not just wastewater, has exacerbated the problem of passing on pollutants to other water users. The dependence of river flow on regular freshwater inputs from precipitation and snowmelt underlines the intrinsic connection between the atmosphere and the water flowing in our rivers.
The nature of anthropogenic activities heavily influences the composition of the earth’s atmosphere, affecting human and ecosystem’s health. According to the WHO, over 91 per cent of the world’s population live in places where the air quality has sunk beyond the recommended limits. Air pollution accounted for over 12 per cent of all deaths in 2019.
To add to these issues, the occurrence of both legacy and new “emerging” organic pollutants has become increasingly common. Chlorinated pesticides used for agriculture and vector control, brominated plastic additives added as flame retardants for fire resistance, fluorinated surfactants used in non-stick cookware, and many such chemicals are all examples of persistent organic pollutants (POPs), which pose immense risk to human health owing to their ability to resist degradation.
Other compounds, including pharmaceuticals and plasticisers, are deemed to be pseudo-persistent because of their constant release into the environment. Some of these chemicals are carcinogenic, can cause endocrine disruption and mutagenicity. Despite being present at trace levels in the environment, chronic human exposure to these toxic compounds can significantly impact health.
During the recent Covid-19 pandemic, day-to-day and regular commercial activities were crippled and pollutants in air like PM10, PM2.5, oxides of sulphur and nitrogen saw a marked decline in their concentrations. Some surface water quality characteristics, like dissolved oxygen levels and nutrient concentrations, showed slight improvements in the riverwater.
However, despite a slowdown in economic activities, the presence of POPs in the environment will continue to linger for decades despite decreased manufacturing and use. Once released into the environment, POPs continue to occur due to their persistence. POPs can also undergo long-range atmospheric transport (dubbed “grasshopper effect”) and exhibit the tendency for transboundary movement, affecting non-source regions. Thus, even if there was no emission of these pollutants in a particular region, these areas can still be affected by exposure to POPs transported from hundreds of kilometre away.
(Paromita Chakraborty is an Associate Professor, SRM Research Institute SRM Institute of Science & Technology, Kattankulathur, India. Prof Daniel Snow is Laboratory Director, Water Sciences Laboratory, University of Nebraska-Lincoln/Nebraska Water Center, USA. The Water Science Laboratory, part of the Nebraska Water Center and Daugherty Water for Food Global at the University of Nebraska, is at the forefront of emerging pollutants analysis including steroids, pharmaceuticals and other toxicants. Environmental Science & Technology Group at SRM Research Institute, Department of Civil Engineering, Institute of Science and Technology, has developed protocols especially for wastewater-based epidemiological surveillance and concurrence of SARS-CoV-2 with chemical markers during this pandemic.)