Urbanization: an increasing source of multiple pollutants to rivers in the 21st century

TLDR

Urbanization will concentrate most of the world’s population in cities, exacerbating already severe river pollution in regions such as Europe, South‑East Asia, and North America, though advanced wastewater treatment offers a technical solution. The study investigates how urbanization will affect future river pollution using a multi‑pollutant framework to aid assessment in urban areas. The authors model point‑source inputs of nutrients, microplastics, triclosan, and Cryptosporidium to over ten thousand rivers across 2010, 2050, and 2100, incorporating socio‑economic development and urbanization/wastewater treatment scenarios. Projections show that by 2100, about 80% of the global population will live in sub‑basins with multi‑pollutant problems, with Africa’s river pollution expected to rise 11–18 fold, threatening Sustainable Development Goals and clean water availability.

Abstract

Abstract Most of the global population will live in urban areas in the 21st century. We study impacts of urbanization on future river pollution taking a multi-pollutant approach. We quantify combined point-source inputs of nutrients, microplastics, a chemical (triclosan) and a pathogen ( Cryptosporidium ) to 10,226 rivers in 2010, 2050 and 2100, and show how pollutants are related. Our scenarios consider socio-economic developments and varying rates of urbanization and wastewater treatment. Today, river pollution in Europe, South-East Asia and North America is severe. In the future, around 80% of the global population is projected to live in sub-basins with multi-pollutant problems in our high urbanization scenarios. In Africa, future river pollution is projected to be 11–18 times higher than in 2010, making it difficult to meet Sustainable Development Goals. Avoiding future pollution is technically possible with advanced wastewater treatment in many regions. In Africa, however, clean water availability is projected to remain challenging. Our multi-pollutant approach could support effective water pollution assessment in urban areas.