A Comparative Assessment of Runoff Nitrogen from Turf,Forest, Meadow,and Mixed Landuse Watersheds

Landscaping paradigms that encourage high‐input, intensively managed and mono‐culture turf/lawn landscapes have raised concerns about water quality. We conducted a watershed‐scale assessment of landscaping practices that included turf, urban, forest, native meadow, and mixed landuse watersheds with a professional golf course and a parking lot. The turf site was moderately managed and had lower fertilizer inputs than those typically used by homeowners and golf courses. Stream water sampling was performed during base flow and storm events. Highest nitrate and total nitrogen concentrations in runoff were observed for the mixed watershed draining the golf course. In contrast, concentrations in base flow from the turf watershed were lower than expected and were comparable to those measured in the surrounding meadow and forest sites. Total nitrogen concentrations from the turf site increased sharply during the first storms following fertilization, suggesting that despite optimal management there exists a risk for nutrient runoff following fertilization. Overall, this study suggests that turf or lawns, when managed properly, pose minimal water quality risk to surface waters. Rate, timing of application, and the type of fertilizer appear to be the key factors affecting water quality. Better education of homeowners and landscaping professionals with regard to these factors may be a cost‐effective strategy to reduce nonpoint source pollution.     

Observations on the methane oxidation capacity of landfill soils

The objective of this study was to determine the role of CH₄ loading to a landfill cover in the control of CH₄ oxidation rate (g CH₄ m⁻² d⁻¹) and CH₄ oxidation efficiency (% CH₄ oxidation) in a field setting. Specifically, we wanted to assess how much CH₄ a cover soil could handle. To achieve this objective we conducted synoptic measurements of landfill CH₄ emission and CH₄ oxidation in a single season at two Southeastern USA landfills. We hypothesized that percent oxidation would be greatest at sites of low CH₄ emission and would decrease as CH₄ emission rates increased. The trends in the experimental results were then compared to the predictions of two differing numerical models designed to simulate gas transport in landfill covers, one by modeling transport by diffusion only and the second allowing both advection and diffusion. In both field measurements and in modeling, we found that percent oxidation is a decreasing exponential function of the total CH₄ flux rate (CH₄ loading) into the cover. When CH₄ is supplied, a cover’s rate of CH₄ uptake (g CH₄ m⁻² d⁻²) is linear to a point, after which the system becomes saturated. Both field data and modeling results indicate that percent oxidation should not be considered as a constant value. Percent oxidation is a changing quantity and is a function of cover type, climatic conditions and CH₄ loading to the bottom of the cover. The data indicate that an effective way to increase the % oxidation of a landfill cover is to limit the amount of CH₄ delivered to it.     

Anionic surfactant remediation of soil columns contaminated by nonaqueous phase liquids

A variety of column experiments have been completed for the purpose of selecting and evaluating suitable surfactants for remediation of nonaqueous phase liquids (NAPLs). The various NAPLs tested in the laboratory experiments were tetrachloroethylene (PCE), trichloroethylene (TCE), jet fuel (JP4) and a dense nonaqueous phase liquid from a site at Hill Air Force Base, UT. Both Ottawa sand and Hill field soil were used in these experiments. Surfactant candidates were first screened using phase behavior experiments and only the best ones were selected for the subsequent column experiments. Surfactants which showed high contaminant solubilization, fast coalescence times, and the absence of liquid crystal phases and gels during the phase behavior experiments were tested in soil column experiments. The primary objective of the soil column experiments was to identify surfactants that recovered at least 99% of the contaminant. The secondary objective was to identify surfactants that show low adsorption and little or no loss of hydraulic conductivity during the column experiments. Results demonstrated that up to 99.9% of the contaminants were removed as a result of surfactant flooding of the soil columns. The addition of xanthan gum polymer to the surfactant solution was shown to increase remediation efficiency as a lower volume of surfactant was required for recovering a given volume of NAPL. Based on these experimental results, guidelines for designing highly efficient and robust surfactant floods have been developed and applied to a field demonstration.     

Application of CCME Water Quality Index to Monitor Water Quality: A Case Study of the Mackenzie River Basin, Canada

All six ecosystem initiatives evolved from many years of federal, provincial, First Nation, local government and community attention to the stresses on sensitive habitats and species, air and water quality, and the consequent threats to community livability. This paper assesses water quality aspect for the ecosystem initiatives and employs newly developed Canadian Council of Ministers of the Environment Water Quality Index (CCME WQI) which provides a convenient mean of summarizing complex water quality data that can be easily understood by the public, water distributors, planners, managers and policy makers. The CCME WQI incorporates three elements: Scope – the number of water quality parameters (variables) not meeting water quality objectives (F ₁); Frequency – the number of times the objectives are not met (F ₂); and Amplitude. the extent to which the objectives are not met (F ₃). The index produces a number between 0 (worst) to 100 (best) to reflect the water quality. This study evaluates water quality of the Mackenzie – Great Bear sub-basin by employing two modes of objective functions (threshold values): one based on the CCME water quality guidelines and the other based on site-specific values that were determined by the statistical analysis of the historical data base. Results suggest that the water quality of the Mackenzie-Great Bear sub-basin is impacted by high turbidity and total (mostly particulate) trace metals due to high suspended sediment loads during the open water season. Comments are also provided on water quality and human health issues in the Mackenzie basin based on the findings and the usefulness of CCME water quality guidelines and site specific values.     

INFLUENCE OF REMOTE SENSING IMAGERY SOURCE ON QUANTIFICATION OF RIPARIAN LAND COVER/LAND USE1

ABSTRACT: This paper compares approaches to quantifying land cover/land use (LCLU) in riparian corridors of 23 watersheds in Oregon's Willamette Valley using color infrared aerial photography (AP) and Thematic Mapper (TM) imagery. For each imagery source, LCLU adjacent to stream networks were quantified across a range of lateral and longitudinal scales. Single‐date AP data had higher LCLU class accuracies than the multi‐date TM data, except for row crops. Correlations among LCLU classes for the two imagery sources increased with increased spatial extent. In general, LCLU proportions for AP and TM differed, but lateral/longitudinal patterns were similar. An aggregated vegetation class comprised of forest, shrub/scrub, and grass/forb was strongly associated with a fish index of biotic integrity (IBI) for both AP and TM data, although AP correlations were higher. Highest fish IBI correlations for both data sources were with the aggregated vegetation class close to the stream and for the longest longitudinal scales. The row crop class was strongly associated with stream nitrate for both data sources, although correlations for the TM data were higher. Stream nitrate correlations were strongest for the widest lateral and longest longitudinal scales. Overall, both single‐date AP and multi‐date TM imagery appear to have potential for use in estimating indicators of stream ecological condition.     

An Experiment Testing whether Condition and Survival are Limited by Food Supply in a Reintroduced Hihi Population

Abstract: The Hihi (Stitchbird, Notiomystis cincta ) is an endemic New Zealand honeyeater that after European colonization survived on only one offshore island. Attempts to reintroduce Hihi to other islands have been unsuccessful, with populations slowly declining. The main hypothesis for these declines was an inadequate year-round supply of carbohydrate food (nectar and fruit) due to human impacts on the forest habitat. When Hihi were reintroduced to Mokoia, another island with regenerating forest, we tested whether survival was limited by carbohydrate food in the year after release. We conducted an "on-off" experiment in which ad libitum sugar water was available to birds for 2 out of every 4 weeks. We compared the masses of individual birds at the end of on and off periods to identify times when birds lost condition with no supplementary food and would be likely to starve. We also used mark-recapture analysis of resighting data to test whether mortality rates were higher when supplementary food was unavailable. The only effect of the supplementary food was that Hihi spent less time foraging for nectar and fruit and more time foraging for invertebrates. There was no time of year when birds lost mass when the food was taken away, and survival rates were not significantly lower when supplementary food was absent. The low (38%) annual survival rate could not be accounted for by shortage of carbohydrate food, and population viability analysis suggests that the population is likely to slowly decline. Our experiment shows that declines of reintroduced Hihi populations may be unrelated to food supply and that alternative hypotheses should be developed and tested. Our results also show the importance of using experimental methods, when possible, to test hypotheses about factors thought to be limiting reintroduced populations.     

Urban riverbank residents' evaluation of flood evacuation policies in Winnipeg,Manitoba, Canada

The results of a discrete choice experiment (DCE) as a part of a survey among the urban riverbank residents on the Red River in Winnipeg, Manitoba, Canada, indicated that the risk of over-dike flooding, set at 2ft above the 1997 flood water level, was a significant determinant of both voluntary and mandatory evacuation, compared to those set at the 1996 or 1997 levels. Mandatory evacuation was more preferred over voluntary evacuation when the likelihood of flooding was at its most severe, and the opposite relationship was the case when the likelihood was low. The notification time for evacuation, suggested as 1, 2, and 4 days, proved to be an insignificant attribute, whereas the respondents indicated significant preference for full flood compensation over an offer of either 80% or 90% flood relief, irrespective of the alternatives of voluntary or mandatory evacuation.     

Flux by fin: fish-mediated carbon and nutrient flux in the northeastern Gulf of Mexico

Seagrass meadows are among the most productive ecosystems in the marine environment. It has been speculated that much of this production is exported to adjacent ecosystems via the movements of organisms. Our study utilized stable isotopes to track seagrass-derived production into offshore food webs in the northeastern Gulf of Mexico. We found that gag grouper (Myctereoperca microlepis) on reefs as far as 90 km from the seagrass beds incorporate a significant portion of seagrass-derived biomass. The muscle tissue of gag grouper, a major fisheries species, was composed on average of 18.5–25% seagrass habitat-derived biomass. The timing of this annual seagrass subsidy appears to be important in fueling gag grouper egg production. The δ³⁴S values of gag grouper gonad tissues varied seasonally and were δ³⁴S depleted during the spawning season indicating that gag utilize the seagrass-derived biomass to support reproduction. If such large scale trophic subsidies are typical of temperate seagrass systems, then loss of seagrass production or habitat would result in a direct loss of offshore fisheries productivity.     

Manure application technology in reduced tillage and forage systems: a review

Managing manure in reduced tillage and forage systems presents challenges, as incorporation by tillage is not compatible. Surface-applied manure that is not quickly incorporated into soil provides inefficient delivery of manure nutrients to crops due to environmental losses through ammonia (NH3) volatilization and nutrient losses in runoff, and serves as a major source of nuisance odors. An array of technologies now exist to facilitate the incorporation of liquid manures into soil with restricted or minor soil disturbance, some of which are new: shallow disk injection; chisel injection; aeration infiltration; pressure injection. Surface banding of manure inforages decreases NH3 emissions relative to surface broadcasting, as the canopy can decrease wind speed over the manure, but greater reductions can be achieved with manure injection. Soilaeration is intended to hasten manure infiltration, but its benefits are not consistent and may be related to factors such as soildrainage characteristics. Work remains to be done on refining its method of use and timing relative to manure application, which may improve its effectiveness. Placing manure under the soil surface efficiency by injection offers much promise to improve N use efficiency through less NH3 volatilization, reduced odors and decreased nutrient losses in runoff, relative to surface application. We identified significant gaps in our knowledge as manyof these technologies are relatively new, and this should help target future research efforts including environmental, agronomic, and economic assessments.     

Use of Small-area Data to Support a Community Agenda in Boston Chinatown

Boston Chinatown is a community that grapples with a constant pressure from the downtown area to build new and larger buildings. The effort to preserve the residential aspect of Chinatown has used data analysis in recent years by forming partnerships with academics. This has allowed for more sophisticated studies of traffic injuries, scientific surveys of residents about environmental health, the measurement of noise levels and the construction of physical and electronic mapping of data. While not the only factor contributing to the community's efforts to question the role of development, these data have added useful tools that reduce, but do not eliminate, the disparity between what the community brings to discussions about the environmental impact of development and what the developers have at their disposal.