Ecological-health risks assessment and source identification of heavy metals in typical greenhouse vegetable production systems in Northwest China

Due to the high cropping index and substantial agricultural inputs in greenhouse vegetable production systems (GVP), the environmental problems caused by heavy metals in GVP are becoming increasingly serious. A systematic investigation of heavy metals accumulation was carried out in GVP located in Jingyang, Shaanxi, China. The accumulation of Cd and Hg was assessed to be more significant than that of other elements in these GVP soils. The pollution load index (PLI) confirmed that 98.9% of the soil samples showed a moderate level of pollution. Additionally, the potential ecological risk index (RI) values indicated that 63.7 and 14.3% of the area was at moderate and high ecological risk, respectively. In assessing the human health risks associated with vegetable consumption, the highest target hazard quotient (THQ) was that for As, followed by Cu > Cd > Zn > Pb > Hg > Cr. Although the hazard index (HI) values were below 1 except for three sample sites in the study area, the 95% quantile of forecasted HI values was 1.22. More attention should be devoted to heavy metal pollution in GVP products. Positive matrix factorization (PMF) was used to identify the sources of the heavy metals. Cu and Zn accumulation were the results of fertilizer overuse; the parent material was the primary source of the As, Pb, and Cr; and the sources of Cd and Hg were inorganic fertilization and industrial emissions, respectively. Effective measures should be implemented to reduce future ecological and health risks in GVP.