Lead adsorption to metal oxides and organic material of freshwater surface coatings determined using a novel selective extraction method

doi:10.1016/S0269-7491(02)00104-5

Environmental Pollution

Volume 119, Issue 3, October 2002, Pages 317-321

https://doi.org/10.1016/S0269-7491(02)00104-5 Get rights and content

Abstract

Surface coatings were collected in three lakes and a river in China to study the role of the components of natural surface coatings in controlling Pb adsorption. Chemical reagents, 0.02 mol/l NH₂OH HCl+0.01 mol/l HNO₃, 0.4 mol/l Na₂S₂O₄ and 10% oxalic acid, were employed to extract one or more components from surface coatings, and then Pb adsorption to extracted and unextracted surface coatings was carried out. The observed Pb adsorption to extracted and unextracted surface coatings were analyzed using the nonlinear least squares fitting (NLSF) to estimate the relative contribution of components to the total Pb adsorption. The amounts of Pb absorption to components described by estimated Γ^max ranged from 0.1126 to 0.7291 (mol Pb/mol Mn) for Mn, 0.0528 to 0.1927 (mol Pb/mol Fe) for Fe and 0.0196 to 0.1020 (mol Pb/kg COD) for organic material, respectively. In all waters studied, metal oxides contributed most to Pb adsorption with a lesser role indicated for organic material.

Introduction

Because of toxicity, the fate of Pb and other trace metals in aquatic environments have drawn great interest. It has been found that solid phases, including sediments, suspended particles and the surface coatings associated with them, play very important roles in the cycling and bioavailability of heavy metals (Vuceta and Morgan, 1978, Santschi et al., 1997). Metal oxides, especially iron and manganese oxides, and organic material are very important components of the solid phases for their capacities of adsorbing heavy metals (Sigg, 1985, Nelson et al., 1999a, Lion et al., 1988, Headley et al., 1998). Nelson et al. (1999a) used an additive model to study the role of the components of surface coatings in controlling Pb adsorption. A novel method of selective extraction followed by Pb adsorption and statistical analysis were employed by Dong et al. (2000) to evaluate the relative contributions of components of surface coatings to Pb adsorption to surface coatings collected in Cayuga Lake. The purpose of the work reported here is to study the relative contributions of Fe oxides, Mn oxides and organic material to Pb adsorption to different natural surface coatings in China, using the same routine as employed by Dong et al. (2000).

Section snippets

Collection of natural surface coatings

Three lakes and a river, Jingyuetan Lake, Nanhu Lake, Songhuahu Lake and Songhua River in Jilin Province, China, were chosen as the aquatic environments to develop natural surface coatings. At each field site, precleaned glass slides (5.0×7.5×0.1 cm) fixed in polypropylene racks were submerged in the water at a depth of about 30 cm for 2 weeks in the fall of year 2000.

Extraction of surface coatings

The extraction techniques employed were the modification of the extraction techniques studied by Dong et al., 2000, Dong et al.,

Results and discussion

The composition of unextracted and extracted surface coatings developed in the four waters in China and in Cayuga Lake in USA is listed in Table 2. The content of components of surface coatings developed in different waters varied remarkably and the extraction efficiency of each extractant for surface coatings developed in those waters was different as well.

It shows in Table 2 that NH₂OH HCl can remove Mn oxides ranged up to 70–96% from surface coatings, and only small part of Fe oxides (<15%)

Conclusions

This study using extraction and statistical analysis method shows that although the relative contributions of components of surface coatings are different in these waters, the metal oxides contribute most to Pb adsorption by surface coatings and the role of organic phases is relatively small in all the waters studied here. These results also indicate a strong influence of Mn oxides on Pb adsorption in natural surface coatings, particularly at environmentally relevant low Pb concentration.

Acknowledgements

This work was supported by Trans-Century Training Program Foundation for the Talents, Supporting Program Foundation for Outstanding Faculties in Chinese Universities by the State Education Ministry of P. R. China, and National Natural Science Foundation (20077011).

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Lead adsorption to metal oxides and organic material of freshwater surface coatings determined using a novel selective extraction method

Abstract

Introduction

Section snippets

Collection of natural surface coatings

Extraction of surface coatings

Results and discussion

Conclusions

Acknowledgements

Microchemical Journal

Water Research

Marine Chemistry

Rates of sorption and partitioning of contaminants in river biofilms

Environmental Science and Technology