Title

Evaluation of spatial variability of soil arsenic adjacent to a disused cattle-dip site, using model-based geostatistics

Document Type

Article

Publication details

Niazi, NK, Bishop, TFA & Singh, B 2011, 'Evaluation of spatial variability of soil arsenic adjacent to a disused cattle-dip site, using model-based geostatistics', Environmental Science and Technology, vol. 45, no. 24, pp. 10463-10470.

Published version available from:

http://doi.org/10.1021/es201726c

Abstract

This study investigated the spatial variability of total and phosphate-extractable arsenic (As) concentrations in soil adjacent to a cattle-dip site, employing a linear mixed model-based geostatistical approach. The soil samples in the study area (n = 102 in 8.1 m2) were taken at the nodes of a 0.30 × 0.35 m grid. The results showed that total As concentration (0-0.2 m depth) and phosphate-extractable As concentration (at depths of 0-0.2, 0.2-0.4, and 0.4-0.6 m) in soil adjacent to the dip varied greatly. Both total and phosphate-extractable soil As concentrations significantly (p = 0.004-0.048) increased toward the cattle-dip. Using the linear mixed model, we suggest that 5 samples are sufficient to assess a dip site for soil (As) contamination (95% confidence interval of ±475.9 mg kg-1), but 15 samples (95% confidence interval of ±212.3 mg kg-1) is desirable baseline when the ultimate goal is to evaluate the effects of phytoremediation. Such guidelines on sampling requirements are crucial for the assessment of As contamination levels at other cattle-dip sites, and to determine the effect of phytoremediation on soil As.