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

Xiaobo Xue Romeiko

doi:10.3390/su11102743

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.

Highlights

Irrigation plays a critical role in boosting crop yield, ensuring food security and stabilizing the global food market
Compared with the existing life cycle assessment (LCA) on rain and groundwater fed corn, the life cycle global warming impact of corn estimated by this study was 10% higher than the average of reported values, mainly due to the inclusion of energy intensive irrigation processes and relatively lower yield rates [33,49,50,51]
This study presented the first comparative LCA study of crop systems irrigated with groundwater and reclaimed water in Northern China

Summary

Introduction

Irrigation plays a critical role in boosting crop yield, ensuring food security and stabilizing the global food market. Numerous studies have reported environmental and human health concerns with utilizing reclaimed water for irrigation [2,3] These studies investigated the accumulation of heavy metals and nutrients [4,5]; the environmental fate of organics in the wastewater irrigated soils [6,7]; the influence of reuse schemes on catchment hydrology [2]; the risk models for helminth infections [8,9]; microbiological contamination risks for aquifers and surface waters [8,10,11]; the transfer efficiencies of chemical contaminants from soil to plants, and the health effects of chronic exposure to chemical contaminants [12,13,14]. Despite extensive experimental and modeling efforts, the life cycle assessment (LCA) of crop systems irrigated with reclaimed water is still lacking [15,16,17]

Objectives

Methods

Results

Discussion

Conclusion