Plant species, biomass and environmental characteristics of relevés along the North America Arctic bioclimate gradient

Question: How do interactions between the physical environment and biotic properties of vegetation influence the formation of small patterned-ground features along the Arctic bioclimate gradient? Location: At 68° to 78°N: six locations along the Dalton Highway in arctic Alaska and three in Canada (Banks Island, Prince Patrick Island and Ellef Ringnes Island). Methods: We analysed floristic and structural vegetation, biomass and abiotic data (soil chemical and physical parameters, the n-factor [a soil thermal index] and spectral information [NDVI, LAI]) on 147 microhabitat releves of zonalpatterned-ground features. Using mapping, table analysis (JUICE) and ordination techniques (NMDS). Results: Table analysis using JUICE and the phi-coefficient to identify diagnostic species revealed clear groups of diagnostic plant taxa in four of the five zonal vegetation complexes. Plant communities and zonal complexes were generally well separated in the NMDS ordination. The Alaska and Canada communities were spatially separated in the ordination because of different glacial histories and location in separate floristic provinces, but there was no single controlling environmental gradient. Vegetation structure, particularly that of bryophytes and total biomass, strongly affected thermal properties of the soils. Patterned-ground complexes with the largest thermal differential between the patterned-ground features and the surrounding vegetation exhibited the clearest patterned-ground morphologies.

(Table 1) Concentrations of the main organochlorine pesticides in liver and plasma samples of ringed seals (Phoca hispida)

The present study investigates the concentrations and patterns of organochlorine pesticides (OCPs) and their metabolites in liver and plasma of two ringed seal populations (Phoca hispida): lower contaminated Svalbard population and more contaminated Baltic Sea population. Among OCPs, p,p'-DDE and sum-chlordanes were the highest in concentration. With increasing hepatic contaminant concentrations and activities of xenobiotic-metabolizing enzymes, the concentrations of 3-methylsulfonyl-p,p'-DDE and the concentration ratios of pentachlorophenol/hexachlorobenzene increased, and the toxaphene pattern shifted more towards persistent Parlar-26 and -50 and less towards more biodegradable Parlar-44. Relative concentrations of the chlordane metabolites, oxychlordane and -heptachlorepoxide, to sum-chlordanes were higher in the seals from Svalbard compared to the seals from the Baltic, while the trend was opposite for cis- and trans-nonachlor. The observed differences in the OCP patterns in the seals from the two populations are probably related to the catalytic activity of xenobiotic-metabolizing enzymes, and also to differences in dietary exposure.

Biological effects and interactions of pesticides in a soil-plant-water microcosm /

Mode of access: Internet.

General information on applying for registration of pesticides in the United States.

"June, 1989."

New innovative pesticides : an evaluation of incentives and disincentives for commercial development by industry /

Mode of access: Internet.

Degradation of pesticides by algae /

Prepared for U.S. Environmental Protection Agency, Office of Research and Development, Environmental Research Laboratory, Athens, Ga., under grant no. R800371.

Pesticides and polychlorinated biphenyls in the Atchafalaya Basin, Louisiana /

"September 1979."

Determination of incinerator operating conditions necessary for safe disposal of pesticides /

Mode of access: Internet.

Polyurethane foam as trapping agent for airborne pesticides : analytical method development /

"Interagency agreement no. 78-D-XO449."

Assessing UST corrective action technologies : early screening of clean-up technologies for the saturated zone /

Mode of access: Internet.

Regulating pesticides.

Mode of access: Internet.

Evaluation of hose-end sprayers used for applying liquid pesticides /

Mode of access: Internet.

Citizen's guide to pesticides.

Mode of access: Internet.

Pesticides monitoring journal

Mode of access: Internet.

Environmental monitoring reports from the 1982 Maine Cooperative Spruce Budworm Suppression Project.

Cover title.