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ARS Home » Pacific West Area » Parlier, California » San Joaquin Valley Agricultural Sciences Center » Water Management Research » Research » Publications at this Location » Publication #328537
Title: Accumulation of Cr, Cd, Pb, Cu, and Zn by plants in tanning sludge storage sites: opportunities for contamination bioindication and phytoremediation

Author
item YUAN, YONGQIANG - Chinese Academy Of Sciences
item YU, SHEN - Chinese Academy Of Sciences
item Banuelos, Gary
item HE, YUNFENG - Zhejiang University

Submitted to: Environmental Science and Pollution Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/23/2016
Publication Date: 9/23/2016
Citation: Yuan, Y., Yu, S., Banuelos, G.S., He, Y. 2016. Accumulation of Cr, Cd, Pb, Cu, and Zn by plants in tanning sludge storage sites: opportunities for contamination bioindication and phytoremediation. Environmental Science and Pollution Research. 23(22):22477-22487. doi: 10.1007/s11356-016-7469-4.

Interpretive Summary: Chromium (Cr), one of the priority pollutants and a well-established carcinogen, has attained wide public and regulatory attention. Pnthropogenic activities, such as, leather tanning, stainless steel production, plating, refractory material processing, pigment production, and wood preservation contributed greatly to Cr pollution in the environment. The lack of appropriate disposal strategies of tanning sludge (e.g., uncontrolled landfills and disposing sludge to open areas) has led to severe Cr pollution in waters and soils in many developing countries. Specific vegetation genotypes have developed biological mechanisms to tolerate high concentrations of metals, and thrive on metalliferous soils. Hence, phytoextraction technologies have been considered as a green remediation approach to metal-contaminated soils. The aim of this study was to assess the metal accumulating ability of plant species growing in Cr contaminated tanning sludge storage sites and determine if any could be potentially used for phytoremediation. Ratio of metals in plant to soil was used as a bio-indicator for the phytoextraction abilities of plants. The plant species red goosefoot, saltmarsh aster, and Chinese cabbage accumulated the highest concentrations of Cr and other heavy metals, and thus they might be considered as better candidates for phytoremediation. Other native species (e.g., reed, zephyr lily, bermuda grass, and alligator weed) accumulated moderately high concentration of Cr, Cu (Copper), Zn (Zinc), Cd (Cadmium), and Pb(lead)in the study areas, which were recognized as good bioindicators of heavy metal pollution. Two vegetable species (Chinese cabbage and edible amaranth) accumulated unacceptably high concentrations of Cr, Cd, and Pb, exceeding the maximum permissible limit; therefore, consumption of these vegetables could have a direct impact on the health of nearby inhabitants. Cropping with metal-accumulating plants could perhaps prove to be an effective and practical means of removing metals from soils contaminated with various metal-polluted waste materials.

Technical Abstract: The lack of appropriate disposal strategies of tanning sludge (e.g., uncontrolled landfills and disposing sludge to open areas) has led to severe Cr pollution in waters and soils in many developing countries. Excessive Cr can be highly toxic to many living organisms and may damage the ecosystem. In the past decades, a great number of metal-tolerant and -accumulating plant species have been identified. Plant species that tolerate metal concentrations are known as hyperaccumulators. Generally, hyperaccumulator species are excellent candidates for phytoextraction. Native plant species surviving on metal rich soils may provide useful germplasm resources for remediation of toxic metals like Cr. In this study, metal accumulating ability was evaluated in native plant species growing in tanning sludge storage sites, a major source of Cr contamination. Plant samples from 14 different species were collected from six tannery sites.Rhizosphere soil samples were collected at the same sites. Concentrations of Cr and other metals (Cu, Zn, Cd and Pb) were analyzed in an acid digestion solution using inductively coupled plasma-mass spectrometry. Results showed the following Cr concentrations (mg kg-1) in red goosefoot (372), saltmarsh aster, (311) and Chinese cabbage (300), and slightly lower levels of Cr were found in reed (155) and edible amaranth (144). Moderately high levels of Cr were detected in bermuda grass (40-96), zephyr lily (74), and alligator weed (70), while Cr concentrations in other native species were less than 15, e.g., oleander contained only 5 mg Cr kg-1. In general, plants with higher Cr concentration were present in soils with higher Cr concentrations (significant correlations r=0.470 (p<0.01) were found between mean Cr concentrations in plants and in soils). Despite high concentrations of metals found in the studied soils, the studied areas have naturally revegetated in the past decades as plants became adapted over time to the locally elevated metal levels. For phytoremediation strategies, our data identifies natural plant species that may be useful for extracting Cr from highly polluted soils.