A Comparative Life Cycle Assessment of Crop Systems Irrigated with the Groundwater and Reclaimed Water in Northern China

Abstract

Using reclaimed water from treated wastewater as an irrigation source is gaining popularity in arid and semi-arid areas. However, life cycle assessment studies, utilizing experimental data to analyze the environmental and health impacts of crops irrigated with reclaimed water, are lacking. This study presents the first comparative life cycle assessment of corn, soybean and wheat systems irrigated with groundwater and reclaimed water in Northern China. While the life cycle foreground inventory was based on a combination of experimental and modeling datasets, the life cycle background inventory was compiled with commercially available data packages augmented with Chinese electricity mix data. The life cycle impact analyses were based on the characterization factors from state-of-art life cycle impact assessment models. The analyses indicated that the life cycle global warming impacts of the crop systems ranged from 0.37 to 0.64 kg CO2-eq/kg grain, with reclaimed water irrigated soybean and ground water irrigated wheat exhibiting, respectively, the lowest and highest global warming impacts. Irrigation, farming equipment operation, on-field emissions and fertilizer production ranked as top contributors to the life cycle impacts for corn, soybean, and wheat. The comparative analyses of irrigation sources suggested that significant environmental tradeoffs existed. Replacing groundwater with reclaimed water as the irrigation source significantly decreased life cycle global warming, acidification, ozone depletion, smog formation, and respiratory impacts of corn, soybean and wheat systems. However, replacing groundwater with reclaimed water increased the life cycle noncancer impacts of those systems. Coordinating policies within the water–food–health nexus is required, in order to minimize the environmental tradeoffs, while maximizing the benefits of irrigation with reclaimed water.