1. Types of surface water pollution. Pollution of sea waters

Types of surface water pollution

Surface water pollution includes pollution of rivers, lakes and oceans. A subset of surface water pollution is marine pollution which affects the oceans. Nutrient pollution refers to contamination by excessive inputs of nutrients.
Globally, about 4.5 billion people do not have safely managed sanitation as of 2017, according to an estimate by the Joint Monitoring Programme for Water Supply and Sanitation. Lack of access to sanitation is concerning and often leads to water pollution, e.g. via the practice of open defecation: during rain events or floods, the human feces are moved from the ground where they were deposited into surface waters. Simple pit latrines may also get flooded during rain events.
As of 2022, Europe and Central Asia account for around 16% of global microplastics discharge into the seas.
Nutrient pollution, a form of water pollution, refers to contamination by excessive inputs of nutrients. It is a primary cause of eutrophication of surface waters (lakes, rivers and coastal waters), in which excess nutrients, usually nitrogen or phosphorus, stimulate algal growth.[41] Sources of nutrient pollution include surface runoff from farm fields and pastures, discharges from septic tanks and feedlots, and emissions from combustion. Raw sewage is a large contributor to cultural eutrophication since sewage is high in nutrients. Releasing raw sewage into a large water body is referred to as sewage dumping, and still occurs all over the world. Excess reactive nitrogen compounds in the environment are associated with many large-scale environmental concerns. These include eutrophication of surface waters, harmful algal blooms, hypoxia, acid rain, nitrogen saturation in forests, and climate change.
The most common case is chemical contamination.Runoff from plants, factories, and fields usually contains harmful chemicals. Laws and regulatory agencies require factories and plants to treat wastewater. For this, special cleaning facilities should be installed. However, even treated wastewater is contaminated to some extent. Laboratories always check for contaminants. In most cases, contamination is invisible because the contaminants are dissolved in the water. Increased concentrations of toxic heavy metals (cadmium, mercury, lead, chromium), pesticides, nitrates and phosphates, petroleum products, surfactants, drugs and hormones washed off from the fields may have been detected in the water.