title: Spatio-temporal patterns of Cu contamination in mosses using geostatistical estimation.
abstract: Several recent studies have reported temporal trends in metal contamination in mosses, but such assessments did not evaluate uncertainty in temporal changes, therefore providing weak statistical support for time comparisons. Furthermore, levels of contaminants in the environment change in both space and time, requiring space-time modelling methods for map estimation. We propose an indicator of spatial and temporal variation based on space-time estimation by indicator kriging, where uncertainty at each location is estimated from the local distribution function, thereby calculating variability intervals for comparison between several biomonitoring dates. This approach was exemplified using copper concentrations in mosses from four Portuguese surveys (1992, 1997, 2002 and 2006). Using this approach, we identified a general decrease in copper contamination, but spatial patterns were not uniform, and from the uncertainty intervals, changes could not be considered significant in the majority of the study area.
authors.affiliation: CERENA, Instituto Superior Técnico, Technical University of Lisbon, Lisboa, Portugal. anabela.s.martins@ist.utl.pt
authors.forename: Anabela
authors.initials: A
authors.lastname: Martins
authors.forename: Rui
authors.initials: R
authors.lastname: Figueira
authors.forename: António Jorge
authors.initials: AJ
authors.lastname: Sousa
authors.forename: Cecília
authors.initials: C
authors.lastname: Sérgio
mesh_terms: D044002:Bryophyta / Q000737:chemistry*; D003300:Copper; D004784:Environmental Monitoring / Q000379:methods*; D004785:Environmental Pollutants / Q000032:analysis*; D004787:Environmental Pollution / Q000706:statistics & numerical data*; D011174:Portugal; D013223:Statistics as Topic
chemical_list: D004785:Environmental Pollutants; D003300:Copper