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About 50% of U.S. water pollution problems are caused by non-point source (NPS) pollution, primarily sediment and nutrients from agricultural areas, despite the widespread implementation of agricultural Best Management Practices (BMPs). However, the effectiveness of implementation strategies and type of BMPs at watershed scale are still not well understood. In this study, the Soil and Water Assessment Tool (SWAT) ecohydrological model was used to assess the effectiveness of pollutant mitigation strategies in the Raccoon River watershed (RRW) in west-central Iowa, USA. We analyzed fourteen management scenarios based on systematic combinations of five strategies: fertilizer/manure management, changing row-crop land to perennial grass, vegetative filter strips, cover crops and shallower tile drainage systems, specifically aimed at reducing nitrate and total suspended sediment yields from hotspot areas in the RRW. Moreover, we assessed implications of climate change on management practices, and the impacts of management practices on water availability, row crop yield, and total agricultural production. Our results indicate that sufficient reduction of nitrate load may require either implementation of multiple management practices (38.5% with current setup) or conversion of extensive areas into perennial grass (up to 49.7%) to meet and maintain the drinking water standard. However, climate change may undermine the effectiveness of management practices, especially late in the 21st century, cutting the reduction by up to 65% for nitrate and more for sediment loads. Further, though our approach is targeted, it resulted in a slight decrease (~5%) in watershed average crop yield and hence an overall reduction in total crop production, mainly due to the conversion of row-crop lands to perennial grass. Such yield reductions could be quite spatially heterogeneously distributed (0 to 40%).

Abstract This paper examines the impact of alternate world oil price assumptions on the long-term economic outlook for Alberta, as determined by a provincial econometric model. Under each of three oil price scenarios, three distinct future periods are identified for the main oil producing region in Canada, ie Alberta. The first period exhibits a recession versus expansion in the economy and a complete divergence in real GDP between the upper and lower oil price scenarios. However, this GDP gap is reduced by the end of the second period as all scenarios tend to converge. Although the GDP is varied among the different scenarios, the last period is seen to require diversification away from energy industries in order to sustain healthy growth. The study results suggest that, due to the limited life index of conventional oil and gas reserves and projected slow growth in long-term oil prices, the provincial government should encourage the development of non-conventional resources or implementa comprehensive policy of industrial diversification towards non-resource based industries in the current period.

Abstract The radiological environment around Wolsong NPP site has been monitored since Wolsong Unit 1 started commercial operation in 1983, as required by regulations in Korea. As a result of the periodic safety review on Wolsong Unit 3 & 4 in 2011, the regulator recommended that an assessment on the long-term accumulation trend of environmental radioactivity around Wolsong Unit 3 & 4 should be performed. In response to this, the assessment was performed based on environmental monitoring data and non-parametric statistical tool (i.e., Mann–Kendall Test). The environmental monitoring data included indicator organisms, soil and marine deposit which were usually monitored for verification of the typical radioactivity level. Most results of the assessment showed no trend and only a few results showed a slight increase. It was concluded that the radioactivity accumulation due to the operation of the plant was insignificant and thus no concern has been raised regarding any effect on the safety and health of the residents around Wolsong NPP site. It is expected that the result of this study could be utilized to establish the plan and policy for environmental monitoring at other NPP sites.

ABSTRACTThis study investigated the interaction between microbial growth and cell elution, and their influence on resultant microbial distribution between the aqueous and solid phases during solute transport in a sandy, low‐organic‐carbon‐content porous medium. Miscible displacement experiments were conducted with salicylate as the model compound, and with different initial conditions (e.g., substrate concentrations and cell densities) to attain various degrees of microbial growth. For each experiment, salicylate and dissolved oxygen concentrations as well as cell densities were monitored in the column effluent. Cell densities were also measured in the porous medium at the beginning and end of each experiment. Total microbial growth was determined in two ways, one based on a cell mass balance for the system and the other based on total amount of salicylate degraded. For conditions yielding a considerable amount of microbial growth, the majority of the biomass was associated with the aqueous phase (68–90%). Conversely, under minimal‐growth conditions, most cells (approximately 60–70%) were attached to particle surfaces. Significant cell elution was observed for most conditions, the rate of which increased in the presence of the substrate. The results suggest that the increase in aqueous‐phase cells observed for the experiments exhibiting the greatest growth is associated with the production of new cells, and that under appropriate conditions aqueous‐phase biomass can contribute significantly to contaminant biodegradation.

Transverse and longitudinal dispersion in gravity stable, favourable viscosity ratio flows are investigated and compared with earlier data obtained for miscible fluids and for tracer flow. Data from laboratory measurements of longitudinal dispersion in low viscosity ratio (8.63×10(-)(4)) and high density contrast (471 kg m(-3)) displacements are compared with literature data for more modest viscosity ratios and density differences and with earlier theoretical analysis. The longitudinal dispersivity was reduced by a factor of 2 for flows influenced by gravity. This reduction was relatively insensitive to the magnitude of the density contrast and the flow rate, for Peclet numbers less than 100 and found to be consistent with earlier theoretical predictions. Additional transverse dispersion data was obtained for fluids with a density contrast of 225 kg m(-3) and a matched viscosity ratio over a range of Peclet numbers (1

Regulatory inspection and violation reports provide insight into the impact of natural gas extraction on the surrounding environment, human health, and public safety. Inspection reports for natural gas wells in Pennsylvania were collected from the Pennsylvania DEP Compliance Report from 2000 to 2014. Analysis of 215,444 inspection records for 70,043 conventional and unconventional wells was conducted in order to compare the odds of violations occurring under different circumstances. Logistic regression models were used to estimate the probability of violations occurring for both conventional and unconventional wells. When inspected, conventional wells had 40% higher odds of having a violation. However, unconventional wells had higher odds for environmental violations related to waste discharge as well as cementing and casing failures. Large operators had 40% lower odds of having any violation than smaller operators. While larger operators had fewer violations, a few of the largest companies had rates of violation much higher than the average for all operators, with some reaching violation rates as high as 1 in 4 active wells. A well also has a higher chance of being in violation if it is in the first year (85%) or second year (109%) since its spud date.

Abstract The dissolution of carbon dioxide (CO 2 ) in deep saline aquifer water is recognized as one of the fundamental mechanisms in the subsurface for storing significant quantities of CO 2 . One fundamental physical effect of CO 2 dissolution is the slight increase in water density in the layer in contact with the buoyant free-phase CO 2 plume. Under specific conditions, this may lead to gravitational instability and the onset of free convection, significantly accelerating the dissolution of the free-phase CO 2 by bringing CO 2 in contact with a larger volume of aquifer water. It is also feasible to enhance CO 2 dissolution using engineering methodologies such as injecting water on top of the plume of CO 2 . The objective of this review is to provide a perspective on the progress in modeling and experimental observations of physical aspects of CO 2 dissolution in deep saline aquifers. We review the published research efforts concerning the physical effects of CO 2 dissolution in formation water, the conditions under which process can be accelerated either naturally, such as by free convection, or by use of engineering methodologies, and the effects of CO 2 dissolution on CO 2 storage. Finally, we discuss areas in need of further research.

The climate change induced by global warming has raised concerns over safety of coastal and offshore infrastructure. At several places in the world therefore studies are being made to know the effect of such change on design and operational ocean parameters. This paper is oriented in this direction and its aim is to specify future changes in the design significant wave height (Hs) over a series of locations along the Indian coastline. Thirty-nine sites were selected along the 7000-km-long Indian coast and design Hs with a return period of 100 years were calculated on the basis of past as well as future wave data of duration 27 years each. The simulation of waves was done by running a numerical wave model forced by wind derived from a modeling experiment called CORDEX. Fitting of data to Generalized Pareto Distribution gave the 100-year Hs at all 39 locations. The results indicate that the design Hs calculated on the basis of projected data was much higher than the one based on historical data. Such increase was as small as 5 % and as high as 58 % as per the location. The west coast sites showed a higher rise in the Hs value than the east ones.

Abstract There is a concern that underground stored CO 2 may potentially escape and intrude shallow aquifers that may lead to degradation of the water quality and possible mobilization of metals. Moreover migrating CO 2 gas may invade buildings causing lethal conditions for humans. A better understanding of gaseous CO 2 migration in heterogeneous aquifer systems at low pressure will help in risk assessment of Carbon Capture and Storage (CCS). We performed complementary 1D column and 2D tank experiments by injecting gaseous CO 2 at three different rates into constructed heterogeneous porous media in laboratory setups. Soil moisture sensors were installed in the test systems to monitor the movement of the gaseous phase. The generated experimental data was analyzed using the numerical multiphase modeling code T2VOC. The results confirmed that large-scale heterogeneity controls overall gaseous CO 2 migration in porous media while processes occurring at smaller scale are of significance for gas saturations. Monitoring the exact gaseous movement and concentrations is difficult even in a constructed heterogeneous medium and point measurements are not always capturing the full dynamics of the system. The numerical model provided good estimates of the general flow of the gaseous phase around larger heterogeneous features and estimated the total amount of gaseous CO 2 in the test system to a good approximation. However, the numerical model was not able to adequately describe the processes occurring at smaller scale including unstable gaseous movement at low flow rates and dissolution of CO 2 .