Four wetland plant species (Scirpus validus, Carex lacustris, Phalaris arundinacea, and Typha latifolia) were grown in monoculture and as a four-species mixture to compare effectiveness of nutrient removal in controlled 18.93-l outdoor subsurface treatment wetland microcosms. A nutrient treatment that mimicked single-resident domestic effluent consisted of two levels of nitrogen (N) and phosphorus (P) [low (56 mg/l N and 31 mg/l P) and high (112 mg/l N and 62 mg/l P)] of nutrient solution applied three times weekly. The plants were established and maintained for one year before the nutrient treatment and monthly water sampling commenced; water sampling began July 31, 2001 and ended October 23, 2001. We tested four hypotheses: (1) vegetated microcosms are more effective at reducing concentrations of total N and total P from soil leachate than unvegetated, (2) there is a differential species effect on the potential to reduce N and P, (3) plant mixtures are more effective than monocultures at reducing N and P, and (4) the microcosms will be least effective at reducing N and P concentrations in October compared to August. We found support for hypotheses 1, 2, and 4, but our results are inconclusive for the third hypothesis. Total N and total P in the soil leachate were significantly higher from unvegetated microcosms compared to vegetated. S. validus was most effective and P. arundinacea was generally least effective at reducing N and P in monocultures, with treatment capabilities similar to unvegetated microcosms. The four-species mixture was generally highly effective at nutrient removal, however the results were not significantly different from the monocultures. At the end of the growing season (October) treatment efficiency was significantly less than earlier months, especially for the unvegetated treatment.

Treatment wetlands can remove nutrients from inflow sources through biogeochemical processes. Plant composition and temperature play important roles in the nutrient removal efficiency of these wetlands, but the interactions between these variables are not well understood. We investigated the seasonal efficiency of wetland macrophytes to reduce soil leachate concentrations of total nitrogen and total phosphorus in experimental microcosms. Each microcosm contained one of six vegetation treatments: unplanted, planted with one of four species (Carex lacustris, Scirpus validus, Phalaris arundinacea and Typha latifolid) in monoculture or planted with an equal abundance of all four species. Microcosms were also subjected to two temperature treatments: insulated microcosms and microcosms exposed to environmental conditions. A constant nutrient solution containing 56 mg/l N and 31 mg/l P was added to all microcosms three times a week. Water samples were analyzed monthly for total dissolved nitrogen and total dissolved phosphorous. Microcosms exhibited a typical pattern of seasonal nutrient removal with higher removal rates in the growing season and lower rates in the winter months. In general, planted microcosms outperformed unplanted microcosms. Among the plant treatments, Carex lacustris was the least efficient. The four remaining plant treatments removed an equivalent amount of nutrients. Insulated microcosms were more efficient in the winter and early spring months. Although a seasonal pattern of nutrient removal was observed, this variation can be minimized through planting and insulation of wetlands.

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Single-family constructed wetland systems in Ohio, USA, are studied to evaluate their effectiveness in improving water quality. Twenty-one, three-cell systems (septic tank with two wetlands) are found to meet US Environmental Protection Agency (EPA) effluent load guidelines in 68% of the quarterly water quality samples collected from 1994 to 2001. These wetlands most frequently meet EPA standards for mitigation of biochemical oxygen demand (89% below 30 mg/l); total suspended solids (79% below 30 mg/l); and fecal coliform (74% below 1000 counts/100 ml). Phosphorus and ammonia discharge meet the guidelines less often (50% at 1 mg/l and 16% at 1.5 mg/l, respectively). These data also indicate that domestic treatment wetlands can reduce output of fecal coliform 88 9 27%, total suspended solids 56 953%, biochemical oxygen demand 70 948%, ammonia 56 931% and phosphorus 80 920%. Analysis of variance for these systems indicates that biochemical oxygen demand reduction is 10% less efficiently reduced during winter and ammonia was reduced 20% more efficiently in fall when compared with the other seasons. Phosphorus reductions display complex seasonal variations that imply that the least efficient phosphorus reduction occurs in winter and the most efficient reduction occurs in fall.

Explosive-source deep seismic reflection data from the southern Ural Mountains of central Russia provided a lithosphere-scale image of the central Eurasian plate that reveals deep reflections (35 to 45 seconds in travel time; ∼130 to 170 kilometers deep) from the mantle. The data display laterally variable reflectivity at the base of the crust that deepens beneath the central part of the profile, documenting a crustal thickness of ∼55 to 60 kilometers beneath the axis of the orogen. These data provide an image of the structure of the crust and underlying mantle lithosphere in a preserved collisional orogen, perhaps to the base of the lithosphere.

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Conceptests are higher-order multiple-choice questions that focus on one key concept of an instructor's major learning goals for a lesson. When coupled with student interaction through peer instruction, conceptests represent a rapid method of formative assessment of student understanding, require minimal changes to the instructional environment and introduce many of the recognized principles of effective teaching that enhance student learning. In this study, instructors from several different institutions developed over 300 conceptests for the geosciences. These instructors then used this suite of concept questions in a wide range of classroom settings, including large introductory general education Earth Science courses for non-majors at open enrollment institutions, smaller physical geology classes suitable for majors at private colleges, and in introductory geology laboratory settings. Results of pre-and post-class Geoscience Concept Inventory (GCI) testing and qualitative feedback from students and instructors showed that conceptests increased attendance, improved student satisfaction, and enhanced student achievement. Participating instructors found implementation of conceptests into their classes straightforward and required less than 30 minutes of preparation per class. The conceptest question database is available on-line for geoscience instructors.