The accumulation of heavy metals in agricultural land and the associated potential ecological risks in Shenzhen, China

Abstract

Accumulation of heavy metals in agricultural land and their ecological risks are key issues in soil security studies. This study investigated the concentrations of six heavy metals-copper (Cu), zinc (Zn), lead (Pb), nickel (Ni), and chromium (Cr) in Shenzhen's agricultural lands and examined the potential hazards and possible sources of these metals. Eighty-two samples from agricultural topsoil were collected. Potential ecological risk index was used to calculate the potential risk of heavy metals. Principal component analysis (PCA) was applied to explore pollution sources of the metals. Finally, Kriging was used to predict the spatial distribution of the metals' potential ecological risks. The concentrations of the heavy metals were higher than their background values. Most of them presented little potential ecological risk, except for the heavy metal cadmium (Cd). Four districts (Longgang, Longhua, Pingshan, and Dapeng) exhibited some degree of potential risk, which tended to have more industries and road networks. Three major sources of heavy metals included geochemical processes, industrial pollutants, and traffic pollution. The heavy metal Cd was the main contributor to the pollution in agricultural land during the study period. It also poses the potential hazard for the future. High potential risk is closely related to industrial pollution and transportation. Since the 1980s, the sources of heavy metals have evolved from parent rock weathering, erosion, degradation of organics, and mineralization to human disturbances resulting in chemical changes in the soil.

Heavy-Metal Pollution Characteristics and Influencing Factors in Agricultural Soils: Evidence from Shuozhou City, Shanxi Province, China

“…This indicates that Cr and As are associated with and controlled by parent rocks, whereas Cd, together with Hg and Pb, are controlled by anthropic activities. Many studies have found that HM concentration is associated with and controlled by parent rocks [45][46][47]. Wazwaz [48] found that different soils achieve different adsorption degrees between different HMs.…”

Elemental Metals in Agricultural Soils along Two Tributaries of Chaohu Lake: Implication on Soil Erosion Caused Enrichment in Sediments

“…Heavy metals can enter the human body through the chronic low-level intake of soil metals including inhalation of dust, direct ingestion, dermal contact, and consumption of infected animals, farm products which take up heavy metals by absorbing them from contaminated soils or from atmospheric deposition by polluted air (Qu, et al, 2012a, Tsai andLee, 2013). The rapid urban and industrial development and increasing reliance on agrochemicals over the past decades have been verified as a vital factor on the accumulation of heavy metals in agricultural soils (Chen, et al, 2015, Wong, et al, 2002, Wu, et al, 2016. However, the metals can be removed from soil by crop adsorption, leaching soil erosion and weathering (Quinton and Catt, 2007, Salt, et al, 1995, Sun, et al, 2001.…”

Impact of Urbanization on the Soil Environment in Southern Giza Governorate, Egypt

“…One of the most damaging consequences for the environment and human health is the accumulation of heavy metals in agricultural soils, which is closely related to rapid urbanization, exceeding industrial activity, and atmospheric contamination in accordance (Wu et al, 2016 andZhou et al, 2016).…”