Evaluation of precipitation chemistry siting criteria using paired stations from northern Maine and southeastern Texas

Abstract

Two-year precipitation chemistry data records from each of the two paired stations are compared to determine whether the precipitation chemistry is different. In each pair, one of the stations (Caribou, Maine and Victoria, Texas) violates National Atmospheric Deposition Program (NADP) siting requirements, while the other station (Presque Isle, Maine and Beeville, Texas) is in compliance. Methods employed to carry out this study include the calculation of precipitation weighted statistics, the study of logarithmic distributions, the study of regression line residuals, the study of relative sample differences and the use of the non-parametric Wilcoxon test for two matched samples. Results indicate no clear differences occurred between paired stations over a seasonal or longer period of time; however, considerable variation was observed on a weekly basis. Maine stations were in excellent agreement for all ions; Texas stations showed small differences between ions typically associated with soil dust and between ions typically associated with anthropogenic activity.