Element redistribution along hydraulic and redox gradients of low-centered polygons, Lena Delta, northern Siberia

Wetland soils affected by permafrost are extensive in subarctic and arctic tundra. However, this fact does not imply these soils have been sufficiently investigated. In particular, studies of element translocation processes are scarce. This study was conducted (i) to determine the relationship between water and redox regimes in wetland soils in the Siberian tundra, and (ii) to investigate their influence on the distribution of redox sensitive and associate elements (Mn, Fe, P). Major geomorphic units were chosen (microhigh, polygon rim and slope; microlow, polygon center) from two low-centered polygons in the Lena Delta. Within polygons, redox potential, permafrost, and water level were measured during summer in 1999 and 2000 and (related) compared with element distribution. Manganese, Fe, and P accumulations were preferentially observed in aerobic microhighs. Anaerobic conditions in the microlows lead to a mobilization of Mn, Fe, and P. The elements migrate via water and are immobilized at the microhigh, which acts as an oxidative barrier. The element pattern, indicating an upward flux via water along redox gradients, is explained by higher evapotranspiration from soils and vegetation of the microhighs (Typic Aquiturbel) compared with soils and vegetation of the microlows (Typic Historthel). However, in further research this upward transport should be validated using labeled elements

Placement is Everyone’s Business: A Love Letter to Our SSP Coalition

In this introduction to the special issue, the co-editors offer the umbrella term "methods of student self-placement" (SSP) to refer to any placement mechanism that includes student choice so that we can further build theoretical apparatus, gather much-needed empirical data, and subsequently flesh out meaningful differences in approaches. They argue that just as SSP asks us to rethink the mission of first-year writing, it also asks us to rethink some of the divisions in Writing Studies because placement work is meaningful across the university. Ultimately, they conclude that SSP isn't an easy fix for systemic problems in higher education, but it is powerful in fully acknowledging the complexity of placement and meeting students' diverse learning needs.&nbsp

Role of sediment in non-point source salt loading within the upper Colorado River Basin: combined completion report

Submitted to Office of Water Research and Technology, U.S. Dept. of the Interior.August 1981.Bibliography: pages [144]-146.OWRT project nos. B-137-COLO and B-170-COLO