Blowing Smoke in Yellowstone: Air Quality Impacts of Oversnow Motorized Recreation in the Park

Snowmobile use in Yellowstone National Park has been shown to impact air quality, with implications for the safety and welfare of Park staff and other Park resource values. Localized impacts have been documented at several high-use sites in the Park, but the broader spatial variability of snowmobile emissions and air quality was not understood. Measurements of 87 volatile organic compounds (VOCs) were made for ambient air sampled across the Park and West Yellowstone, Montana, during 2 days of the 2002–2003 winter use season, 1 year before the implementation of a new snowmobile policy. The data were compared with similar data from pristine West Coast sites at similar latitudes. Backward trajectories of local air masses, alkyl nitrate-parent alkane ratios, and atmospheric soundings were used to identify the VOC sources and assess their impact. Different oversnow vehicle types used in the Park were sampled to determine their relative influence on air mass pollutant composition. VOCs were of local origin and demonstrated strong spatiotemporal variability that is primarily influenced by levels of snowmobile traffic on given road segments at different times of day. High levels of snowmobile traffic in and around West Yellowstone produced consistently high levels of benzene, toluene, and carbon monoxide.     

Estimating Forest Ecosystem Evapotranspiration at Multiple Temporal Scales With a Dimension Analysis Approach1

Abstract:  It is critical that evapotranspiration (ET) be quantified accurately so that scientists can evaluate the effects of land management and global change on water availability, streamflow, nutrient and sediment loading, and ecosystem productivity in watersheds. The objective of this study was to derive a new semi‐empirical ET modeled using a dimension analysis method that could be used to estimate forest ET effectively at multiple temporal scales. The model developed describes ET as a function of water availability for evaporation and transpiration, potential ET demand, air humidity, and land surface characteristics. The model was tested with long‐term hydrometeorological data from five research sites with distinct forest hydrology in the United States and China. Averaged simulation error for daily ET was within 0.5 mm/day. The annual ET at each of the five study sites were within 7% of measured values. Results suggest that the model can accurately capture the temporal dynamics of ET in forest ecosystems at daily, monthly, and annual scales. The model is climate‐driven and is sensitive to topography and vegetation characteristics and thus has potential to be used to examine the compounding hydrologic responses to land cover and climate changes at multiple temporal scales.     

Watershed Evapotranspiration Increased due to Changes in Vegetation Composition and Structure Under a Subtropical Climate1

Abstract: Natural forests in southern China have been severely logged due to high human demand for timber, food, and fuels during the past century, but are recovering in the past decade. The objective of this study was to investigate how vegetation cover changes in composition and structure affected the water budgets of a 9.6‐km² Dakeng watershed located in a humid subtropical mountainous region in southern China. We analyzed 27 years (i.e., 1967‐1993) of streamflow and climate data and associated vegetation cover change in the watershed. Land use/land cover census and Normalized Difference of Vegetation Index (NDVI) data derived from remote sensing were used to construct historic land cover change patterns. We found that over the period of record, annual streamflow (Q) and runoff/precipitation ratio did not change significantly, nor did the climatic variables, including air temperature, Hamon’s potential evapotranspiration (ET), pan evaporation, sunshine hours, and radiation. However, annual ET estimated as the differences between P and Q showed a statistically significant increasing trend. Overall, the NDVI of the watershed had a significant increasing trend in the peak spring growing season. This study concluded that watershed ecosystem ET increased as the vegetation cover shifted from low stock forests to shrub and grasslands that had higher ET rates. A conceptual model was developed for the study watershed to describe the vegetation cover‐streamflow relationships during a 50‐year time frame. This paper highlighted the importance of eco‐physiologically based studies in understanding transitory, nonstationary effects of deforestation or forestation on watershed water balances.     

Characterizing Storm Hydrograph Rise and Fall Dynamics With Stream Stage Data1

Abstract: Storm‐flow transients (i.e., hydrograph rise and fall dynamics) may represent an important aspect of understanding streamflow dynamics. However, little is known about how temporal resolution of transient data and climate variability may color these potential indicators of hydrologic pattern or condition. Warm‐season stream stage and rainfall were monitored continuously (5 min) during the 2002 water year in eight tributaries of the Little Miami River (Ohio), which drain 17‐58 km² catchments. Rise rates generated using 5‐min data were different than those generated with mean daily data [calculated with the Indicators of Hydrologic Alteration (IHA) software], though fall rates were similar for fine and coarse temporal data. This result suggests that data with low temporal resolution may not be adequate to fully represent the dynamics of storm rise rates. Conversely, fall rates based on daily stage data (via IHA) were similar to those based on the 5‐min data, and so daily mean data may be appropriate for characterizing fall rates. We next analyzed the possible correlations between rainfall variability and storm‐flow stage dynamics. We derived rise and recession rates from storm stage hydrographs by assuming exponential rise and decay of a runoff peak. We found that raw rise rates (R_raw) were correlated with both the maximum rainfall rate and the time to the centroid of a rain event. We subsequently removed the trend based on these rainfall characteristics, which yielded new representations of rise rates abbreviated as R_rate and R_tcent, respectively, and that had lower variability than the uncorrected (raw) data. Fall rates were found to be independent of rainfall characteristics. Due to the predominant influence of stream hydrology upon aquatic biota and nutrient fluxes, our work suggests that these stage data analysis protocols can refine or otherwise reduce variability in these indices by accounting for relevant factors such as rainfall forcing. These protocols for derivation of transient indices should be tested for their potential to improve correlations between stream hydrology and temporally aligned biotic data and dissolved nutrient fluxes in streams.     

Streambank Soil and Phosphorus Losses Under Different Riparian Land‐Uses in Iowa1

Abstract: Phosphorus and sediment are major nonpoint source pollutants that degrade water quality. Streambank erosion can contribute a significant percentage of the phosphorus and sediment load in streams. Riparian land‐uses can heavily influence streambank erosion. The objective of this study was to compare streambank erosion along reaches of row‐cropped fields, continuous, rotational and intensive rotational grazed pastures, pastures where cattle were fenced out of the stream, grass filters and riparian forest buffers, in three physiographic regions of Iowa. Streambank erosion was measured by surveying the extent of severely eroding banks within each riparian land‐use reach and randomly establishing pin plots on subsets of those eroding banks. Based on these measurements, streambank erosion rate, erosion activity, maximum pin plot erosion rate, percentage of streambank length with severely eroding banks, and soil and phosphorus losses per unit length of stream reach were compared among the riparian land‐uses. Riparian forest buffers had the lowest streambank erosion rate (15‐46 mm/year) and contributed the least soil (5‐18 tonne/km/year) and phosphorus (2‐6 kg/km/year) to stream channels. Riparian forest buffers were followed by grass filters (erosion rates 41‐106 mm/year, soil losses 22‐47 tonne/km/year, phosphorus losses 9‐14 kg/km/year) and pastures where cattle were fenced out of the stream (erosion rates 22‐58 mm/year, soil losses 6‐61 tonne/km/year, phosphorus losses 3‐34 kg/km/year). The streambank erosion rates for the continuous, rotational, and intensive rotational pastures were 101‐171, 104‐122, and 94‐170 mm/year, respectively. The soil losses for the continuous, rotational, and intensive rotational pastures were 197‐264, 94‐266, and 124‐153 tonne/km/year, respectively, while the phosphorus losses were 71‐123, 37‐122, and 66 kg/km/year, respectively. The only significant differences for these pasture practices were found among the percentage of severely eroding bank lengths with intensive rotational grazed pastures having the least compared to the continuous and rotational grazed pastures. Row‐cropped fields had the highest streambank erosion rates (239 mm/year) and soil losses (304 tonne/km/year) and very high phosphorus losses (108 kg/km/year).     

The Predatory Bird Monitoring Scheme: identifying chemical risks to top predators in Britain

The Predatory Bird Monitoring Scheme (PBMS) is a long term (>40 y), UK-wide, exposure monitoring scheme that determines the concentration of selected pesticides and pollutants in the livers and eggs of predatory birds. This paper describes how the PBMS works, and in particular highlights some of the key scientific and policy drivers for monitoring contaminants in predatory birds and describes the specific aims, scope, and methods of the PBMS. We also present previously unpublished data that illustrates how the PBMS has been used to demonstrate the success of mitigation measures in reversing chemical-mediated impacts; identify and evaluate chemical threats to species of high conservation value; and finally to inform and refine monitoring methodologies. In addition, we discuss how such schemes can also address wider conservation needs.     

Growth performance of planted mangroves in the Philippines: revisiting forest management strategies

The effort toward restoring lost mangroves in the Philippines has been commendably immense, specifically during the past two decades. In light of such, it is important to evaluate outcomes and, where appropriate, apply the lessons learned to the current strategies in mangrove forest management. This article synthesizes the results from several research projects assessing the performance of planted mangroves across the country. Overall, there is a widespread tendency to plant mangroves in areas that are not the natural habitat of mangroves, converting mudflats, sandflats, and seagrass meadows into often monospecific Rhizophora mangrove forests. In these nonmangrove areas, the Rhizophora seedlings experienced high mortality. Of the few that survived (often through persistent and redundant replanting), the young Rhizophora individuals planted in these nonmangrove and often low intertidal zones had dismally stunted growth relative to the corresponding growth performance of individuals thriving at the high intertidal position and natural mangrove sites. From this evidence, this article argues that a more rational focus of the restoration effort should be the replanting of mangroves in the brackish-water aquaculture pond environments, the original habitat of mangroves. For such, a number of management options can be explored, the implementation of which will ultimately depend on the political will of local and national governments.     

Sorption of imidazolium-based ionic liquids to aquatic sediments

Ionic liquids (ILs) have received much attention as "green" alternatives to traditional solvents because they do not evaporate, eliminating concerns over fugitive emissions. However, if ionic liquids are used in industrial applications, they may enter aquatic systems via effluent, and their fate and transport may be influenced by sorption to sediments. In this study, we conducted batch mixing experiments with four alkylmethylimidizolium-based ILs and four types of aquatic sediments to asses the capacity for natural aquatic sediments to remove these chemicals from the water column. The concentration isotherms were non linear with point estimates of the distribution coefficient (K(d)) decreasing with increasing concentration. Apparent distribution coefficients ranged from 7.9 to 95.7l kg(-1) at an initial concentration of 0.5mM and were positively related to sediment organic matter (SOM) content. These K(d) values indicate that the ILs did not sorb strongly to the tested sediments. Increased alkyl chain length did not lead to increased sorption suggesting that hydrophobic interactions were not the most important sorption mechanism. We conclude that aquatic sediments have a limited capacity to sorb alkylmethylimidazolium ILs and that the transport of these contaminants in aquatic systems will not be strongly attenuated by sediments.     

PAHs in background soils from Western Europe: influence of atmospheric deposition and soil organic matter

The levels and distribution of polynuclear aromatic hydrocarbons (PAHs) were determined in soil samples from background locations in the UK and Norway, to investigate their spatial distribution and the controlling environmental factors. Concentrations ranged between 42 and 11200 microg kg(-1) (geometric mean 640 microg kg(-1)) and 8.6 and 1050 microg kg(-1) (150 microg kg(-1)) dry weight in the UK and Norwegian soil, respectively. Proximity to sources and locations susceptible to high atmospheric depositional inputs resulted in higher concentrations. Statistically significant relationships were observed between PAH and total organic carbon (TOC) in the Norwegian samples. High molecular weight PAHs correlated with black carbon (BC) in UK-woodland soil. These observations support the hypothesis that TOC plays an important role in the retention of PAHs in soil and that PAHs are often combined with BC during combustion emissions. PAHs with 4 and more rings comprised approximately 90% of total PAHs in the UK soil, but only 50% in the Norwegian soil. The mixture of PAHs implied that fractionation occurred during long-range atmospheric transport and deposition. The lighter PAHs with lower K(ow) values more readily reached the most remote sites. The heavier PAHs with higher K(ow) values remained in closer proximity to sources.     

Evaluation of post-Katrina flooded soils for contaminants and toxicity to the soil invertebrates Eisenia fetida and Caenorhabditis elegans

This research evaluated soil samples from a New Orleans neighborhood in the Chalmette, Saint Bernard Parish, that had been inundated by flooding associated with Hurricane Katrina. The goal was to determine if ecological risks persisted from flood waters that had come in contact with hazardous surface chemicals before inundating this low-lying neighborhood for a prolonged period. Research objectives were to establish the presence or absence of volatile organic and heavy metal contaminants, and then asses the toxicity of this soil to Eisenia fetida in a soil exposure assay and Caenorhabditis elegans in a simulated porewater exposure assay. Soil analysis revealed detectable levels of metals and organics in the surface soil at each location. No contaminant was detected in concentrations above human health screening values. Chromium and mercury were detected at levels in excess of typical ecological risk values. Soil extracts revealed concentrations of nitrate, sulfate, and chloride above those from an unflooded background sample. Toxicity testing resulted in no acute effects to either test species, but did show bioaccumulation of arsenic, cadmium, and lead in E. fetida exposed to several samples. The combination of mercury and sulfate provide the potential for mercury methylation should flooding and prolonged inundation occur again.