Biomedical subjects

Per Sandén

Publications and source records attributed to Per Sandén.

3 recordsLinked to original sources

PubMed2006

Chloride retention and release in a boreal forest soil: effects of soil water residence time and nitrogen and chloride loads.

The common assumption that chloride (Cl-) is conservative in soils and can be used as a groundwater tracer is currently being questioned, and an increasing number of studies indicate that Cl- can be retained in soils. We performed lysimeter experiments with soil from a coniferous forest in southeast Sweden to determine whether pore water residence time and nitrogen and Cl- loads affected Cl- retention. Over the first 42 days there was a net retention of Cl- with retention rates averaging 3.1 mg CI- m(-2) d(-1) (68% of the added Cl- retained over 42 days). Thereafter, a net release of Cl- at similar rates was observed for the remaining experimental period (85 d). Longer soil water residence time and higher Cl- load gave higher initial retention and subsequent release rates than shorter residence time and lower Cl- load did. Nitrogen load did not affect Cl transformation rates. This study indicates that simultaneous retention and release of Cl- can occur in soils, and that rates may be considerable relative to the load. The retention of Cl- observed was probably due to chlorination of soil organic matter or ion exchange. The cause of the shift between net retention and net release is unclear, but we hypothesize that the presence of O2 or the presence of microbially available organic matter regulates Cl- retention and release rates.

Adsorption↗

PubMed2004

Multi-objective environmental management in constructed wetlands.

We examined multi-objective environmental management as applied to pursuing concurrent goals of water treatment, biodiversity and promotion of recreation in constructed wetlands. A case study of a wetland established to treat landfill leachate, increase biodiversity, and promote recreation was evaluated. The study showed that attempts to combine pollution management with activities promoting biodiversity or recreation are problematic in constructed wetlands. This could be because the typical single-objective focus of scientific research leads to contradictions when planning, implementing and assessing the multi-objective use of wetlands. In the specific case of wetland filters for landfill leachate treatment, biodiversity, and recreation, there is a need for further research that meet practical needs to secure positive outcomes.

Animals↗

PubMed2003

Spatial patterns of organic chlorine and chloride in Swedish forest soil.

The concentration of organic carbon, organic chlorine and chloride was determined in Swedish forest soil in the southern part of Sweden and the spatial distribution of the variables were studied. The concentration of organically bound chlorine was positively correlated to the organic carbon content, which is in line with previous studies. However, the spatial distribution patterns strongly indicate that some other variable adds structure to the spatial distribution of organic chlorine. The distribution patterns for chloride strongly resembled the distribution of organic chlorine. The spatial distribution of chloride in soil depends on the deposition pattern which in turn depends on prevailing wind-direction, amount of precipitation and the distance from the sea. This suggests that the occurrence of organic chlorine in soil is influenced by the deposition of chloride or some variable that co-varies with chloride. Two clearly confined strata were found in the area: the concentrations of organic chlorine and chloride in the western area were significantly higher than in the eastern area. No such difference among the two areas was seen regarding the carbon content.

Carbon↗