Marine pollution is a global issue of grave concern. Almost all pollution incepted into the marine environment is anthropogenically induced and holistically includes ocean litter, pesticides and fertilizers, or pollution in the forms of noise, light[sc:1]. Specifically, marine pollution comprises of oil spills from rigs and tankers, untreated sewage from industry, heavy siltation and eutrophication from farming, invasive species from aquaculture and wildlife trafficking, Persistent Organic Pollutants (POP’s), heavy metals and acidification from mining, radioactive substances from nuclear activity, litter from domestic waste and destruction of coastal and marine habitats from overfishing[sc:2].
Overall, despite global governmental and non-governmental efforts to combat marine pollution the situation continues to deteriorate. It is suffice to say that reasonable progress has been made on reducing POP’s as oil discharges and tanker accidents have been reduced by some sixty-three percent and seventy-five percent respectively from a mid-nineteen eighties baseline[sc:2]. However, emissions of heavy metals and sedimentation from coastal development, deforestation and mangrove clearing is generally rising[sc:2].
The worst pollutants
From an agricultural point of view, the use of pesticides and fertilizers has increased by twenty-six fold over the past fifty years which has created serious environmental consequences[sc:1]. Chemical application in farming pollutes regional water bodies with compounds that can kill non-target creatures and ecology. Whilst fertilizers are not directly toxic per se, they can alter the marine environment’s nutrient system and create an intense growth of algae. This can cause water quality depletion through increased levels of dissolved oxygen which is similarly harmful.
Overfishing is arguably the gravest of all detrimental marine activities, but from a pollution perspective it can cause contamination via the sheer amount of fuel, resources and waste created in its process. Another major threat to the marine environment is the physical demolition of marine habitats from dredging. Huge swathes of coastal land is being developed around the world for tourism and other activities that is creating unprecedented levels of untreated sewage being discharged into waters[sc:2]. According to the United Nations Environment Program (2006)[sc:2] the issue of untreated discharged water is estimated to cost some USD 56 billion if it were to be tackled.
Going forwards, a plethora of credible sources and international institutions predict that the marine pollution issue will continue to worsen by 2030. Nitrogen from agricultural run-off is projected to increase at least fourteen percent globally, with more than 600,000 tons being discharged annually from the major rivers of South-East Asia alone. As coastal populations and industrial activities increase in the region from seventy-seven people/km2 to one-hundred and fifteen people per km2 in 2025, these numbers will become further exacerbated. Wetlands and mangroves will also continue to decline rapidly – by up to ninety percent in some regions[sc:2].
All of the above, together with the impacts of a warmer climate through climate change will also increase the salinity of our marine environment and raise water levels through the of melting sea ice which could hold its own set of pollution-related issues.