Geochemistry of stream plants and its statistical relations to soil- and bedrock geology, slope directions and till geochemistry : a GIS-analysis of small catchments in northern Sweden

• Main Author: Eriksson, Harry
• Format: Other/Unknown Material
• Language: English
• Published: Lunds universitet/Institutionen för naturgeografi och ekosystemvetenskap 2017
• Subjects: Biogeochemistry; GIS; Physical Geography and Ecosystem analysis; Geographical Information Systems; Geochemistry; Catchments; Drainage areas; Earth and Environmental Sciences; Northern Sweden
• Online Access: http://lup.lub.lu.se/student-papers/record/8908936

Subaquatic mosses and stream plants have been recognized as suitable sample media for detection of geochemical variations in their surrounding environments. These plants were originally used in search for mineral deposits but later on also for detection of environmental pollution. In this study it is investigated if statistically significant correlations could be detected between element content in subaquatic stream plant roots and some spatial parameters related to their catchments, which not necessarily contain mineral deposits or are polluted. Many small accurately outlined catchments and geological data therein from SGU were compared for a 2500 km2 large area in the inland of Västerbotten, northern Sweden. Research questions: (1) Is there a statistical difference in geochemistry between subaquatic stream plant samples from catchments with different types of bedrock? (2) Is there a statistical difference in geochemistry between subaquatic stream plant samples from catchments with different types of quaternary deposits? (3) Is there a statistical difference in geochemistry between subaquatic stream plant samples from catchments with different dominating down slope directions, north or south? (4) Is there a statistical correlation between the geochemistry of sub aquatic stream plants and the geochemistry of the till soils in their catchments? The main results: (1) For most elements there were no significant correlations between geochemistry, in plant samples and bedrock types. However, some trace elements (Cu, Ni, Rb and Zn) correlated positively with meta-sediments (negatively with granites) and some other (As, Mo, S, U, V, W, Y and Zr) correlated positively with granitic rocks (negatively with meta-sediments). (2) For 6 of 27 elements (Al, Cu, Rb, Sr, U and Y) there were significant decreases in plant samples when percentage of peat cover increased in the catchments. Decrease of detrital particles and trapping of elements in the peat could be possible explanations. The areas of the other cover types (bare ...