Agriculture Reference
In-Depth Information
6
Heavy Metals Contaminated Soils and
Phytoremediation Strategies in Taiwan
Hung-Yu Lai 1 , Shaw-Wei Su 2 , Horng-Yuh Guo 3 and Zueng-Sang Chen 2
1 Department of Post-Modern Agriculture, MingDao University
No. 369, Wen-Hua Rd., Peetow, Changhua,
2 Department of Agricultural Chemistry, National Taiwan University
No. 1, Sec. 4, Roosevelt Rd., Taipei
3 Division of Agricultural Chemistry, Taiwan Agricultural Research Institute
Council of Agriculture; No.189, Jhongjheng Rd., Wufeng, Taichung,
Taiwan
1. Introduction
Heavy metals (HMs) in soils primarily result from the weathering of parent materials and
from human activities, which including mining, smelting, application of sludges, and
discharge of wastewaters, etc. (Kabata-Pendias & Pendias, 2001). Soil contaminated with
HMs has become a worldwide problem and pose a serious threat to the environment
(Anwar et al., 2009), leading to losses in agricultural yield and hazardous health effects as
they enter the food chain (Salt et al., 1995). Cropping lands contaminated by HMs were
mostly resulted from the use of polluted irrigated water in the downstream of discharged
water of industrial parks of Taiwan. In 2007, approximate 400 ha of rural soils in Taiwan
were contaminated with single or combined HMs and they are fallow according to Soil and
Groundwater Pollution Remediation Act (SGWPR Act) announced in 2000 by Taiwan
Environmental Protection Administration (Taiwan EPA). There were many techniques been
used to treat the HMs-contaminated soils which including isolation, mechanical separation,
chemical treatment, electrokinetics, soil washing, and phytoremediation (Mulligan et al.,
2001). Various soil amendments were applied to the HMs-contaminated soils to reduce the
mobility of HMs in the contaminated soils and thus to decrease their further uptake by
crops (Chen & Lee, 1997; Kabata-Pendias and Pendias, 2001; Lee et al., 2004; Mench et al.,
1994).
In Taiwan, most of these contaminated sites were restored with turnover/dilution and acid
washing methods to reduce the total concentration of HM to conform the regulation
announced. Besides the two techniques, phytoremediation was demonstrated to be a
feasible method in treating these contaminated lands, which have large areas and low to
medium level of HM concentration (Lai et al., 2005). It also accompanies with other
environmental agenda, such as biomass energy, biodiversity, carbon sequestration, and soil
quality (Dickinson et al., 2009). However, most hyperaccumulators used in removing these
HMs have lower biomass and growing rate and thus extending the period needed in
decontamination. The application of chemical agents has significant effect on increasing the
phytoavailability and accumulation of HMs of plants (Chen & Cutright, 2001; Meers et al.,
Search WWH ::




Custom Search