Emissions of ammonia, methane, carbon dioxide, and nitrous oxide from dairy cattle housing and manure management systems

Concentrated animal feeding operations emit trace gases such as ammonia (NH?), methane (CH?), carbon dioxide (CO?), and nitrous oxide (N?O). The implementation of air quality regulations in livestock-producing states increases the need for accurate on-farm determination of emission rates. The objective of this study was to determine the emission rates of NH?, CH?, CO?, and N?O from three source areas (open lots, wastewater pond, compost) on a commercial dairy located in southern Idaho. Gas concentrations and wind statistics were measured each month and used with an inverse dispersion model to calculate emission rates. Average emissions per cow per day from the open lots were 0.13 kg NH?, 0.49 kg CH?, 28.1 kg CO?, and 0.01 kg N?O. Average emissions from the wastewater pond (g m(-2) d(-1)) were 2.0 g NH?, 103 g CH?, 637 g CO?, and 0.49 g N?O. Average emissions from the compost facility (g m(-2) d(-1)) were 1.6 g NH?, 13.5 g CH?, 516 g CO?, and 0.90 g N?O. The combined emissions of NH?, CH?, CO?, and N?O from the lots, wastewater pond and compost averaged 0.15, 1.4, 30.0, and 0.02 kg cow(-1) d(-1), respectively. The open lot areas generated the greatest emissions of NH?, CO?, and N?O, contributing 78, 80, and 57%, respectively, to total farm emissions. Methane emissions were greatest from the lots in the spring (74% of total), after which the wastewater pond became the largest source of emissions (55% of total) for the remainder of the year. Data from this study can be used to develop trace gas emissions factors from open-lot dairies in southern Idaho and potentially other open-lot production systems in similar climatic regions.     

Primary NO2 emissions and their impact on air quality in traffic environments in Germany

Background

The decreasing NO_X concentrations at urban measurement stations in Germany are in agreement with the reduction of NO_X emissions from vehicular traffic. However, the measured NO₂ concentrations are stagnating nationwide. In 2010, at more than the half of the urban measurement stations in Germany, annual mean values for NO₂ exceeded the new Europe-wide limit value of 40 μg/m³ (20 ppbv) NO₂. Similar findings are reported from many other member states of the European Union.

Results

The observed trend of the airborne NO₂ concentrations has different reasons. Firstly, the NO₂/NO_x emission ratio has increased significantly during the last two decades. Furthermore, secondary NO₂, caused by the titration reactions of NO with ozone (O₃) and peroxy radicals (RO₂), is responsible for the major fraction (approximately 70%) of the measured NO₂. However, secondary NO₂ shows a highly nonlinear dependency on NO_x and thus, is decreasing much more slowly than expected from the decreasing NO_x levels. Based on the results from the present study, the increased NO₂/NO_X emission ratio can only explain a minor fraction of the observed high airborne NO₂ concentration in the city center.

Conclusions

A further reduction of primary NO₂ emissions, due to improved exhaust gas treatment, will not have a strong influence on urban NO₂ levels, and a further significant reduction of the NO_X emissions, in particular from vehicular traffic, is necessary in order to meet the annual mean limit value for NO₂ of about 20 ppb in the future.     

Community composition and consumer identity determine the effect of resource species diversity on rates of consumption

The effect of species diversity on ecosystem function is commonly studied within a single trophic level, but less is known about how resource diversity affects species interactions between trophic levels. We conducted a grazing experiment to determine how resource species diversity affects rates of consumption by three species of freshwater zooplankton consumers. We measured the effect of resource diversity on rates of consumption for several resource community compositions. These compositions varied in terms of palatability for the consumers. The effect of resource diversity on consumption rates depended on the diet breadth of the consumer species (from specialist to generalist) and the community composition of resources. Overall, high resource diversity commonly caused a decline in consumption rates of consumers. The most selective grazer showed reduced consumption for nearly all community compositions, whereas the most generalist grazer showed accelerated consumption when all resource species were palatable. Our results demonstrate that resource species diversity can modulate rates of consumption through the action of multiple different mechanisms.     

Predicting long-term development of abandoned subalpine conifer forests in the Swiss National Park

In the past 35 years, various kinds of dynamic models have been used to study vegetation development during primary or secondary succession. Typically, one specific model or models with the same conceptual background were employed. It remains largely unknown to what extent such model-based findings, e.g., on the speed of succession, depend on the specific model approach.To address this issue, we estimated the time elapsing during secondary succession in subalpine conifer forests of the Swiss National Park using three models of different conceptual background: (i) a forest gap model, (ii) a Markov chain model, and (iii) a minimum spanning tree model.Starting from a 95- to 125-year-old mountain pine (Pinus montana Miller) forest, all three models predicted a similar successional development. Even though the forest gap model and the Markov chain model are based on totally different approaches and were calibrated using different data sets, they both forecasted that it would take 500–550 years to reach a late-successional forest stage. The minimum spanning tree model, which only reveals a certain number of time steps yielding a minimum time estimate, showed a development of tree density (stems/ha) that was similar to the results of the forest gap model, but a strict quantitative comparison is not feasible.Our study shows that modeling forest development using three different approaches is quite powerful to obtain a robust estimate of the speed of forest succession. In our case, this estimate is higher than what has been suggested in previous studies that investigated secondary forest succession. The use of several approaches allows for a more comprehensive analysis in terms of variables covered (e.g., relative forest cover in the Markov approach vs. stand-scale species composition in the forest gap model). We recommend that in studies focusing on the speed of succession, several models should be employed simultaneously to identify inconsistencies in our knowledge and to increase confidence in the results.     

A comparison of contaminant dynamics in arctic and temperate fish: A modeling approach

In order to compare the abilities of arctic and temperate fish to accumulate PCBs we conduct a metabolic analysis to determine how process rates in a mathematical fish contaminant model change with temperature. We evaluate the model by applying the original and adapted models to estimate PCB concentrations in lake trout (Salvelinus namaycush) in Trout Lake, Ontario, Canada, and in arctic char (Salvelinus alphinus) in Lake ?yangen, in the Norwegian high arctic. Modeled concentrations are, for the most part, within 50% of mean measured values and are comparable to the error associated with the fish data. In order to evaluate differences in fish bioaccumulation processes, the model is applied to hypothetical arctic and temperate systems, assuming the same contaminant input values in water and diet. The model predicts that temperate salmonids are able to biomagnify PCBs 6-60% more than arctic salmonids. For all congeners, the lower BMF(MAX) of arctic fish contribute to their lower concentrations. For congeners with log K(ow) < 6.0, the lower concentrations in arctic fish are also attributed to faster loss due to gill ventilation. Faster growth rates for temperate fish reduce the difference in bioaccumulation for congeners with log K(ow) > 7.0. These processes are controlled by the influence of lipid in the fish and their diet as well as the dependence of growth on temperature. We suggest that fish models originally calibrated for temperate systems may be directly applied to arctic lakes after accounting for the lipid content of the fish and their diet as well as water temperature.     

Analysis of conservative tracer measurement results inside a planted horizontal subsurface flow constructed wetland filled with coarse gravel using Frechet distribution

Environmental Science and Pollution Research - We worked out a method in Maple environment to help understand the difficult transport processes in horizontal subsurface flow constructed wetlands...     

Thermal Characteristics of Stormwater Runoff from Asphalt and Sod Surfaces1

Abstract: Urban impervious surfaces absorb and store thermal energy, particularly during warm summer months. During a rainfall/runoff event, thermal energy is transferred from the impervious surface to the runoff, causing it to become warmer. As this higher temperature runoff enters receiving waters, it can be harmful to coldwater habitat. In an urban watershed, impervious asphalt surfaces (roads, parking lots, and driveways) and pervious residential lawns comprise a significant portion of the watershed area. A paired asphalt‐turfgrass sod plot was constructed to compare the thermal runoff characteristics between asphalt and turfgrass sod surfaces, to identify meteorological variables that influence these thermal characteristics, and to evaluate evaporative heat loss for runoff from asphalt surfaces. Rainfall simulations were conducted during the summers of 2004 and 2005 under a range of climatic conditions. Asphalt surface temperatures immediately prior to rainfall simulations averaged 43.6°C and decreased an average of 12.3°C over 60 min as rain cooled the surface. In contrast, presimulation sod surface temperatures averaged only 23.3°C and increased an average of 1.3°C throughout the rainfall events. Heat transferred from the asphalt to the runoff resulted in initial asphalt runoff temperatures averaging 35.0°C that decreased by an average of 4.1°C at the end of the event. Sod runoff temperatures averaged only 25.5°C and remained fairly constant throughout the simulations. Multivariable regression equations were developed to predict (1) average asphalt surface temperature (R² = 0.90) and average asphalt runoff temperature (R² = 0.92) as a function of solar radiation, rain temperature, and wind speed, and (2) average sod surface temperature (R² = 0.85) and average sod runoff temperature (R² = 0.94) as a function of solar radiation, rain temperature, rain intensity, and wind speed. Based on a heat balance analysis, existing evaporation equations developed from studies on lakes were not adequate to predict evaporation from runoff on a heated impervious surface. The combined heat from the asphalt and sod plots was an average of 38% less than the total heat had the total area consisted solely of asphalt.     

Policy design,spatial planning and climate change adaptation: a case study from Australia

There are gaps in the existing climate change adaptation literature concerning the design of spatial planning instruments and the relationship between policy instruments and the sociopolitical barriers to adaptation reform. To help address this gap, this article presents a typology of spatial planning instruments for adaptation and analyses the pattern of instrument choice in Australian planning processes in order to shed light on contextual factors that can impede adaptation. The analysis highlights how policy design can amplify the barriers to adaptation by arranging policy actors in ways inimical to reform and stripping decision makers of the instruments necessary to make and sustain desired policy changes.