The function of constructed wetland in reducing the risk of heavy metals on human health

Abstract

Irrigation with polluted water from the upper Yellow River (YR) channel of Northwest China has resulted in agricultural soil being contaminated by heavy metals (HMs). This causes major concerns due to the potential health risk to the residents in this area. The present study aims to assess the efficiency of constructed wetland (CW) in reducing the heavy metal contamination in irrigation water and food crops, thus in reduction of potential health risk to the residents. The associated risk was assessed using hazard quotient (HQ) and hazard index (HI). The results showed a potential health risk to inhabitants via consumption of wheat grain irrigated with untreated water from YR. However CW could greatly reduce the human health risk of HMs contamination to local residents through significantly decreasing the concentrations of HMs in wheat grain. In theory, the reduction rate of this risk reached 35.19% for different exposure populations. Therefore, CW can be used as a system to pre-treat irrigation water and protect the residents from the potential HMs toxicity.

Concentration Level of Heavy Metals in Wheat Grains and the Health Risk Assessment to Local Inhabitants from Baiyin, Gansu, China

“…Previous study had shown that wastewater irrigation would cause accumulation of heavy metals in soils [13]. The irrigation water in Baiyin contained high level of heavy metals, especially of Cu, Zn, Pb and Cd [11]. It could be inferred that the high heavy metal concentrations in the agricultural soil might come from the wastewater irrigation.…”

“…In which, DIM means the daily intake of heavy metals calculated using Eq.2 [11]. RfD is an estimation of a daily exposure to the human population that is likely to be without an obvious risk of deleterious effects during a lifetime.…”

“…In which, C metal represents the heavy metal concentrations in grain, D grain intake is the daily intake of grain (the average daily grain intake for adult males, adult females and children were 0.58, 0.36 and 0.16 kg/person/day, respectively [11]) , B average weight is the average body weight according to the national physical fitness study of Gansu province, the average body weight of adult males, females and children were 65.7, 56.3 and 17.5 kg, respectively [11]).…”

Impact of Industrial Pollution of Cadmium on Traditional Crop Planting Areas and Land Management: A Case Study in Northwest China

“…This region is rich in non-ferrous metals such as Cu, Pb, Zn, Co, Au, and Ag, which are locally mined and processed in smelting factories; however, these heavy metals frequently contaminate streams and rivers in this area [25,27]. With the development of the mining and metallurgical industry, arable land in this region has been polluted by Cd, Cu, Pb, and Zn [33,34] because of the usage of polluted river water for irrigation [25]. Crop plants take up such heavy metals and consumption of contaminated crops by humans and/or livestock can result in human/livestock exposure.…”

Retention and mitigation of metals in sediment, soil, water, and plant of a newly constructed root-channel wetland (China) from slightly polluted source water

“…Application of constructed wetland in water treatment has gained popularity throughout the world for its low costs, low energy consumption and minimal operation and maintenance. Constructed wetland can effectively remove heavy metals in water sources and waste water by acting as a matrix, facilitating interaction between microbes and plant/animal communities and performing functions such as filtration, adsorption, precipitation, ionic exchange, microbiological degradation, and biological uptake (Kadlec 2003; Vymazal 2011; Si et al 2011; Malaviya and Singh 2012). Recent reports have focused primarily on the sources and distributions of heavy metals (Zhang et al 2002; Protano et al 2013; Mohammed and Abdu 2013) and on assessing the risks posed by such metals (Xiao et al 2012; Yang et al 2008; Vymazal and Krása 2003; Obarska-Pempkowiak and Klimkowska 1999; Goulet et al 2001).…”