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Hundreds of millions of people are at risk from drinking arsenic (As)-contaminated groundwater in the world, making As removal from aquatic systems of utmost importance. However, characteristics of As removal by bacteria-induced ferrihydrite and coupled with redox processes are still not clear. Two-line ferrihydrite was formed in the presence of aerobic Fe(II)-oxidizing bacterium, Pseudomonas sp. strain GE-1. Arsenic co-precipitation with and adsorption onto ferrihydrite induced by Pseudomonas sp. strain GE-1 and redox processes of As were investigated. Results demonstrated that co-precipitation performed better in As(V) removal than As(III) removal, while adsorption showed higher capacity for As(III) removal. X-ray absorption near-edge spectroscopy (XANES) indicated that As(III) oxidation occurred in solid phases during co-precipitation and adsorption. Detection of As species in solution showed that As(V) was reduced to As(III) during co-precipitation, although no As(V) reduction occurred during adsorption. Arsenic immobilization by Pseudomonas sp. strain GE-1-induced ferrihydrite in the presence of the strains may be applied as an alternative remediation strategy.

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This study compares the growth in salaries across three spatial regions in China during the period 1993-1998, when economic reforms were implemented nationwide. Our study compares the impact of three forms of education and training on salary growth, namely pre-job formal schooling, on-the-job-training provided by employers, and adult education paid for by the employees themselves. We used a three-level hierarchical linear model to partition variance among individual, firm, and regional characteristics. The data were drawn from a 1998 survey of 16 485 employees from 365 firms in six provinces (two provinces in the eastern part of the country, two in the central part, and two in the western part). We found that: (1) regional disparities have a paramount impact on differences in salary; (2) individual characteristics defined by firm as well as firm characteristics are significantly related to salary decisions; (3) returns to formal schooling increase significantly in more market-based regions; and (4) employees also benefit by receiving on-the-job-training and by participating in adult education programs outside their firm.Human capital, salary, hierarchical linear model, China,