Current Directions in Water Scarcity Research, Volume 6 - Chapter 2: Urban water pollution by heavy metals, microplastics, and organic contaminants

The abundance and distribution of various heavy metals, microplastics, and organic contaminants present in the environment pose a major challenge as large quantities of these pollutants are produced and discharged into the surrounding environment every year. In particular, in urban environments, pollutants discharged from chemical and allied industries enter water bodies through urban stormwater discharge or combined sewer overflows, which in turn contribute significantly to water quality deterioration in many areas. Urban areas are the center of key ecological, social, and economic activity. Heavy metals in urban water bodies can pose a serious threat to public health and aquatic lives due to their toxicity, persistence, and bioaccumulation and biomagnification in the food chain. It is important to understand the entry sources, impacts, and control of heavy metals in urban water resources, in order to evaluate the nature and extent of damage to ecosystems. The majority of past research efforts on microplastics focused on documenting their impact on marine environments, and studies on microplastics in surface water bodies have only recently been conducted. As such, the ecological role of microplastics and pellets in urban freshwater bodies is yet to be well understood. The dominant source of organic pollution of urban water bodies is the organic matter derived from a diverse array of human activities, and many of the organic compounds are non-biodegradable, and persistent in the ecosystem. In the last several decades, numerous strategies have been developed to mitigate urban water resources pollution. However, successful implementation of effective water pollution mitigation strategies require a thorough knowledge and understanding of pollution sources and of contaminant behavior in the environment. This chapter aims to critically review previous research on the presence of heavy metals, microplastics, and organic contaminants in urban waters and to synthesize the current knowledge of various urban water pollution sources. This contribution is timely, bearing in mind that Sustainable Development Goals call for developments that balance social, economic, and environmental sustainability.