Human Impact: Polluted Water's Journey Back To Us

Water pollution is a pressing issue that affects human health, the environment, and the economy. It occurs when harmful substances contaminate bodies of water, such as rivers, lakes, and oceans, rendering them unsafe for human use and disrupting aquatic ecosystems. These harmful substances can include toxic waste, petroleum, chemicals, and disease-causing microorganisms. Water pollution can lead to various health issues in humans, such as gastrointestinal diseases, cancer, and cardiovascular conditions. It is caused primarily by human activities, such as industrial waste, agricultural runoff, and sewage discharge, but natural sources like mercury from the Earth's crust can also contribute. With increasing water consumption and deteriorating water quality, addressing water pollution is crucial for ensuring human health, social development, and environmental protection.

Industrial waste and sewage

Industrial wastewater is a common byproduct of industrial and commercial activities. It is the water that has been used in the production of commercial products across every industry, in nearly all phases of production. Once this process water has been used, it becomes waste and must be treated before it is discharged.

The types of industrial waste generated include cafeteria garbage, dirt and gravel, masonry and concrete, scrap metals, trash, oil, solvents, chemicals, weed grass and trees, wood and scrap lumber, and similar wastes. Industrial solid waste can be solid, liquid, or gases held in containers, and it is divided into hazardous and non-hazardous waste. Hazardous waste may result from manufacturing or other industrial processes, and it includes commercial products such as cleaning fluids, paints, or pesticides. Non-hazardous industrial waste does not meet the EPA's definition of hazardous waste and is not municipal waste.

The most abundant nutrients present in wastewater are nitrogen and phosphorus, with the highest concentrations found in sewage and municipal wastewaters. Industrial effluents are generally characterized by high BOD, COD, total organic carbon, and varying pH. The chemical composition of effluents varies from industry to industry, with agricultural and food processing wastewaters containing high BOD, suspended solids, and ammonia nitrogen.

Sources of industrial wastewater include manufacturing, commercial businesses, mining, agricultural production and processing, and wastewater from the cleanup of petroleum- and chemical-contaminated sites. Industrial wastewater treatment aims to remove dissolved or suspended substances, and technologies have been developed to address a wide range of solid waste and other environmental and recycling problems.

The effects of water pollution are devastating to people, animals, fish, and birds. Polluted water is unsuitable for drinking, recreation, agriculture, and industry. It diminishes the aesthetic quality of lakes and rivers, destroys aquatic life, and reduces reproductive ability.

Oil spills and leaks

Oil spills typically spread on the water's surface when they enter the ocean, forming a slick that can be cohesive or break apart due to waves, wind force, and currents. These spills can contain volatile organic components that partially evaporate, making the oil denser and more viscous. Oil spills can also generate air pollutants during the cleanup process, such as nitric oxides and ozone from ships.

One of the significant sources of oil spills is pipelines, contributing an estimated 1% of oil pollution in the oceans. However, this percentage may be underestimated due to underreporting, as many pipeline leaks occur on land. Offshore oil production operations, including drilling and leaks from tankers and ships, contribute to approximately 8% of the total amount of oil waste in the ocean.

Recreational boats, factories releasing untreated waste disposal, and land-based sources such as runoff from cities, cars, highways, and roads also contribute to oil spills. Oil spills can have severe environmental and economic consequences, impacting wildlife and human health. For example, oil can penetrate the plumage of birds and the fur of mammals, reducing their insulating ability and making them more vulnerable to temperature changes and less buoyant in the water.

To address the issue of oil spills and leaks, individuals can take preventive measures such as using less fossil fuel, reducing gas vehicle use, improving fuel efficiency, and transitioning to electric vehicles.

Pesticides and fertilisers

Pesticides are applied to farmlands, gardens, and lawns and can contaminate both surface water and groundwater systems that feed drinking water supplies. Pesticides enter water bodies through chemical runoff during improper storage, loading, disposal, and misapplication of pesticides to water bodies. This is known as point source pollution. Non-point source pollution occurs when rainfall moves through areas that have been sprayed with pesticides, or when pesticides are displaced from absorption sites near water through soil erosion. Paddy fields, which account for about 50% of Japan's agricultural lands, contribute significantly to pesticide contamination in Japanese rivers.

The use of pesticides has helped the United States become the world's largest producer of food. However, it has also raised concerns about the potential adverse effects of pesticides on the environment and human health. Pesticides can affect the nervous, hormonal, and endocrine systems in the human body. Some pesticides are carcinogenic, while others may cause skin and eye irritation. Long-term exposure to low concentrations of pesticides has been linked to non-carcinogenic health risks.

Fertilizers used in crop production can also pollute water resources. When excess fertilizers are applied, the remaining nutrients, particularly nitrogen and phosphorus, remain in the soil and are eventually washed off during irrigation or rainfall, polluting water resources. Phosphates, which are less soluble than nitrates, may adsorb onto soil particles and pollute water through soil erosion. Animal waste used as fertilizer in the aquaculture industry can also pollute water if excess nutrients are introduced.

The presence of pesticides in water is a widespread issue, with almost 90% of water samples from US rivers and streams containing at least five or more different pesticides. The quality of shallow groundwater will improve faster than deep groundwater in response to reductions in chemical applications to the land.

Microplastics and micro-organisms

The presence of microplastics in the environment is causing serious water pollution worldwide. Microplastics are solid particles smaller than 5mm, insoluble in water, and non-biodegradable. They are created when plastics are dismissed into water resources, resulting in splintered debris. They can be found in the air, drinking water, food, and natural freshwater systems, including wetlands, lakes, and rivers. A 2022 study found that microplastics accumulate within the freshwater systems, especially at the source of a river or stream, where the slow water flow allows pollutants to reside for longer.

Microplastics have been detected in marine species, drinking water, and numerous foods such as salt, honey, and other marine organisms. They can be inhaled or ingested and, once absorbed, can distribute to vital organs, including the liver, spleen, heart, lungs, thymus, reproductive organs, kidneys, and brain. They also act as transporters of heavy metals and other pollutants from invertebrates to other higher trophic levels.

The presence of microplastics in drinking water sources has been studied to determine the correlation between microplastics and microorganisms. The abundance of microplastics was found to have a weak correlation with water quality indicators and microorganisms. However, black and transparent microplastics of smaller sizes (50-100 μm) exhibited a more significant association with microorganisms.

Microorganisms initially adsorb microplastics using the EPS they secrete. The microplastics then serve as attachable carriers, aiding the growth of microorganisms. Eventually, the biofilms detach from the carrier's surface, gathering contaminants and contributing to the treated water. While the biofilms effect has been reported to be negligible, the presence of microplastics in water systems is an emerging threat that requires further investigation.

Eutrophication

The effects of eutrophication are far-reaching and detrimental. One of the most noticeable consequences is the formation of dense blooms of phytoplankton and algae, often with unpleasant odours. These blooms reduce water clarity, negatively impacting the survival of many plants and animals. They also deplete dissolved oxygen levels, creating "dead zones" where most organisms cannot survive due to oxygen levels falling below the hypoxic threshold. This reduction in biodiversity is one of the most pressing environmental issues, especially with the increasing demand for freshwater resources.

To address eutrophication, various strategies have been proposed and implemented. These include diverting excess nutrients, altering nutrient ratios, physical mixing of water, and using opaque liners or stains to shade water bodies. The use of algaecides and herbicides has also been suggested, along with the optimization of fertilizer use and the treatment of sewage water before releasing it into water sources. Despite legislative efforts to regulate nutrient loading, eutrophication and algal blooms remain prevalent, and climate change and population growth are expected to further exacerbate the problem.

In the context of the game Once Human, eutrophication may be a concept that players indirectly engage with as they navigate polluted waters and extract polluted water using water pumps. While the game does not explicitly mention eutrophication, the presence of polluted water and the need to extract and purify it reflect the real-world challenges of addressing eutrophication and its consequences.

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