Quantification of temporal changes in metal loads – Moss data over 20 years

Environmental monitoring, assessment and conservation programmes worldwide have led to the development of scientific and technological methods to study the changes in our environment. As a result, a technique for monitoring atmospheric metal deposition was developed in Sweden in the 1960s. This technique is based on the principle that, carpet-forming moss obtains its nutrients from dry deposition particles in the air. The Swedish Environmental Research institute (IVL) has a database of concentrations of metals in terrestrial mosses. These were sampled during the national moss surveys (1975 – 2000). From these point data, long-term changes in the deposition loads can be studied.One aim of this project is to create continuous surfaces for these point data and to develop a technique to map the spatio-temporal changes. It also seeks to quantify the temporal changes in metal loads of the moss data for over 20 years. With the amount of data increasing from various air quality assessments and monitoring methods, it is prudent to approach the data analysis from a multidisciplinary perspective. By using statistics, geostatistic, GIS and visualization methods, the quantitative, spatial and temporal trends of the moss surveys were analysed. Multidimensional visualizations based on exploratory data analysis were applied to the data to visualize and reveal trends in the multivariate data.The project area comprised the whole Sweden with the data from 1975 to 2000, with the exception of the moss survey in 1975, which was conducted only in southern Sweden. A combination of GIS, geostatistics and high dimensional visualization techniques were applied in the data cleaning and analysis stages.The results of the project show the rate of change of metal loads over the years and the spatial distribution of the metal depositions as well. The visual approach used from the data cleaning to results presentation makes it easily comprehensible to non-scientist as well