3.2 How are we polluting our waters?

We are also severely polluting our waters. Since 1980, there has been a ten-fold increase in plastic pollution, with now an estimated 300 kg of plastic entering the ocean every second. This adds up to a staggering 4.8-12.7 million metric tonnes of consumer plastics ending up in the world’s oceans each year. Plastic pollution has resulted in the presence of more than 100 million particles of macroplastics in only 12 regional seas worldwide, and 51 trillion particles of microplastic floating on the ocean surface globally. A recent study found that off the coast of Oregon, USA, there’s an average of 11 tiny pieces of plastic to every oyster. Nearly all of these microplastic pieces came from clothing fibres or abandoned fishing gear.

Unfortunately, recycling isn’t necessarily the answer to this problem. Shockingly, a huge proportion of ‘recycled’ plastic actually ends up in the ocean, buried in landfill or even being burned. Due to ocean currents, there are now areas in the ocean where enormous amounts of plastic collects in one place, resulting in huge 'garbage dumps of the sea'. The Great Pacific Garbage Patch for example, which is halfway between Hawaii and California, contains more than 1.8 trillion pieces of plastic, weighs more than 43,000 cars and is three times the size of France.

Plastics are not the only pollutant in our seas and freshwaters. Pesticides, herbicides, detergents, industrial chemicals, oil and sewage also make their way into our waters, as well as soil eroded from the land by human activities. More than 80% of wastewater resulting from human activities is discharged into rivers or sea without any pollution removal. Nitrates from the use of agricultural fertilisers are now the most common chemical contaminant in our groundwater. Indeed, human activity now produces as much nitrogen on an annual basis as all the world’s natural processes combined. These nitrates can find their way into lakes and coastal waters, and along with phosphates, cause algal blooms which poison waters and dramatically reduce the growth of plants and fish through a process called eutrophication. In addition, 300-400 million tonnes of poisonous heavy metals, solvents, toxic sludge, and other wastes from industrial facilities are dumped annually into the world’s waters.

Flooding can exacerbate this problem, as it can cause chemicals from old mines to be swept up and dumped into rivers and onto farmland. For example, after floods in the UK in 2012, levels of lead were much higher in rivers and were sufficient to kill farm animals grazing on the land.