Spatial and temporal trends rain water chemical species in the Eastern Asia, 2000~2009

초록

Chemical species data on precipitation from the Acid Deposition Monitoring Network in East Asia were analyzed for trends in sulfate, nitrate, ammonium, and pH from the year 2000 to 2009. The 34 sites in the 10 countries were chosen for the trend analysis among the 45 monitoring sites in the 13 countries as of 2009 based on duration of monitoring and duplication of sites. The Acid Deposition Monitoring Network in East Asia monitors rain water chemical compositions and related gas phase chemical species. Data were rejected if percentage of days with measured precipitation plus no precipitation days(PCL) are less than 80% or Percentage of total precipitation amount over the summary period(TP) are less than 80%. And ion balances and measured conductivities versus calculated ones were checked as quality assurance and quality control measure. Taking into non-linear nature of precipitation chemistry and dependency on precipitation amount, the seasonal Kendall trend test and the partial Kendall trend test were chosen instead of tests based on linear regression analysis. Mann Kendall analysis family is a basic non-parametric test for trend testing. Its only background assumption is that the random variable is independent and identically distributed and the strength of the monotonic relationship between parameters is measured as probability. The seasonal Kendall test compares only the data pairs from the same season and the partial Kendall test extracts meteorological effects on rainwater compositions by calculating covariance.