Strategies for the prediction of acid mine drainage

A comprehensive 1 year study has been carried out to evaluate and compare methods to predict the formation of acid mine drainage (AMD) and to make recommendations on the methods most suitable for laboratory and field use. This paper presents the findings of this study and includes a brief description of methods evaluated, a summary of the test results, and a discussion on the ability of the methods to accurately predict field behaviour. A principal conclusion made from the results of the study is that accurate and confident prediction of AMD is not likely to be achieved in a single test. Factors affecting the choice of test procedures to be used for a given tailing or waste rock are discussed on the basis of simplicity, time, equipment, cost, ease of interpretation, and correlation with field data. In addition, approaches to be used in the selection of AMD prediction methods for site specific applications involving either land-based or sub-aqueous waste deposition are outlined.Applied Science, Faculty ofNon UBCMining Engineering, Keevil Institute ofUnreviewedOthe

A detailed urinary excretion time course study of captan and folpet biomarkers in workers for the estimation of dose, main route-of-entry and most appropriate sampling and analysis strategies

Captan and folpet are two fungicides largely used in agriculture, but biomonitoring data are mostly limited to measurements of captan metabolite concentrations in spot urine samples of workers, which complicate interpretation of results in terms of internal dose estimation, daily variations according to tasks performed, and most plausible routes of exposure. This study aimed at performing repeated biological measurements of exposure to captan and folpet in field workers (i) to better assess internal dose along with main routes-of-entry according to tasks and (ii) to establish most appropriate sampling and analysis strategies. The detailed urinary excretion time courses of specific and non-specific biomarkers of exposure to captan and folpet were established in tree farmers (n = 2) and grape growers (n = 3) over a typical workweek (seven consecutive days), including spraying and harvest activities. The impact of the expression of urinary measurements [excretion rate values adjusted or not for creatinine or cumulative amounts over given time periods (8, 12, and 24 h)] was evaluated. Absorbed doses and main routes-of-entry were then estimated from the 24-h cumulative urinary amounts through the use of a kinetic model. The time courses showed that exposure levels were higher during spraying than harvest activities. Model simulations also suggest a limited absorption in the studied workers and an exposure mostly through the dermal route. It further pointed out the advantage of expressing biomarker values in terms of body weight-adjusted amounts in repeated 24-h urine collections as compared to concentrations or excretion rates in spot samples, without the necessity for creatinine corrections