Health risks of industrial wastewater heavy metals based on improved grey water footprint model

Abstract

The Belt and Road Initiative (B&RI) promotes cooperation among participating countries from multiple perspectives, especially infrastructure construction and investment, which is a critical driving force for industrial activities. The accelerated industrial development would inevitably cause environmental consequences in participants, in which pollution and related health risks caused by industrial heavy metal emissions were among the most concerned. In this study, an improved grey water footprint of industrial heavy metal emissions (GWFHMs) was proposed from the perspective of health risks to address the limitation of conventional GWF in reflecting their properties and impacts of pollutants, such as the health toxicity of heavy metals. Meanwhile, the water pollution level of GWFHMs (WPLHMs) was estimated to reveal the degree of aquatic industrial heavy metal pollution concerning health risks. We use China, the B&RI member with severe heavy metal pollution, as a case. The spatial distribution of GWFHMs (at the resolution of 1 km × 1 km) and WPLHMs (at the watershed level) monthly during 1998–2015 were uncovered. Results show that the GWFHMs of China have significantly decreased in this period, but WPLHMs in some regions are still high due to cyclical fluctuations in heavy metal emissions and water runoffs. The middle reaches of the Yangtze River had the highest GWFHMs but relatively low WPLHMs due to abundant water runoffs. In contrast, the Liaohe watersheds in north China had the highest WPLHMs due to water shortage, especially in dry seasons (from December to February). This study reveals critical periods and hotspot regions for heavy metal pollution, which would support decision-making for delicacy industrial heavy metal control measures concerning human health in B&RI countries. In addition to direct emission control, production activities and the following industrial wastewater emissions should also consider the time variation of water runoffs in each region, which would contribute to keeping the health risks of industrial heavy metal emissions within acceptable limits.