AFTER THE 1993 FLOOD: A WATER AND SURFICIAL BED SEDIMENT QUALITY SCENARIO ON THE ILLINOIS AND UPPER MISSISSIPPI RWERS1

ABSTRACT: Effects of the 1993 flood on river water and sediment quality were investigated using historical data and data collected from the Illinois River and Upper Mississippi River in a post‐flood period. Overall the post‐flood results showed systematic reductions and individual changes in the water and sediment constituents. The reductions in sediment metals and nutrients were most obvious at the Keokuk and Lock and Dam 26 stations. By analyzing and comparing the physical changes to the changes in water and sediment constituents at each station, it was found that physical processes such as sediment entrainment and, more importantly, the removal of fine sediment to be the main causes for the reduced concentrations in sediment constituents. On the other hand, sediment redistribution and associated secondary contamination could have caused the emergence of several water and sediment constituents that were undetected before the flood.     

WATER USE AND WATER CONSERVATION BY THE COPPER MINING INDUSTRY1

ABSTRACT: This paper examines the use of water by copper mines for treating low grade ores. The froth flotation process for treating sulphide ore and the heap leaching process for treating oxide ore are described, and ways of reducing the amount of water used in these processes are discussed. Estimates of the costs reducing water consumption are given. Finally, the circumstances in which it would be desirable for a copper mine to reduce its level of water consumption are considered.     

Ecosystem responses to climate change at a Low Arctic and a High Arctic long-term research site

Long-term measurements of ecological effects of warming are often not statistically significant because of annual variability or signal noise. These are reduced in indicators that filter or reduce the noise around the signal and allow effects of climate warming to emerge. In this way, certain indicators act as medium pass filters integrating the signal over years-to-decades. In the Alaskan Arctic, the 25-year record of warming of air temperature revealed no significant trend, yet environmental and ecological changes prove that warming is affecting the ecosystem. The useful indicators are deep permafrost temperatures, vegetation and shrub biomass, satellite measures of canopy reflectance (NDVI), and chemical measures of soil weathering. In contrast, the 18-year record in the Greenland Arctic revealed an extremely high summer air-warming of 1.3 °C/decade; the cover of some plant species increased while the cover of others decreased. Useful indicators of change are NDVI and the active layer thickness.     

MUNICIPAL RESPONSES TO VOLATILE ORGANIC COMPOUNDS IN WISCONSIN GROUND WATER1

ABSTRACT: Contamination of ground water supplies with volatile organic compounds is a new and significant problem. Municipalities and their community water systems are often the first to discover ground water contamination because of the monitoring programs they are required to carry out. When contamination exceeds standards, some action is required. The responses of Wisconsin municipalities to volatile organic compounds that exceed standards in their ground water sources is described. Actions to protect human health are prompt, but the survey results indicate plumes of contaminated ground water are usually not treated. They may continue to migrate and contaminate other private and public wells.     

Factors influencing waste separation and utilization among households in the Lake Victoria crescent,Uganda

Wastes, which are the by-products of consumption, are a growing problem in the urban and peri-urban areas of the Lake Victoria region largely due to high urban population growth rates, consumption habits, low collection rates and hence waste accumulation. Whereas the biodegradable proportion is high and could be reutilized, a few have tapped the economic potential of this waste. This study was conducted to explore the potential alternatives and determinants of waste separation and utilization among urban and peri-urban households in the Lake Victoria crescent. A random sample of households in five urban and peri-urban areas of the crescent were selected and surveyed. Logit models were used to establish the factors influencing waste separation and utilization in urban and peri-urban areas of the lake crescent. Results indicate that, gender, peer influence, land size, location of household and membership of environmental organization explain household waste utilization and separation behaviour. Campaigns for waste separation and reuse should be focused in the peri-urban areas where high volumes of wastes are generated and accumulate. Social influence or pressure should be used to encourage more waste reuse and separation.     

A coastal cliff management district for protection of eroding high relief coasts

Ensuring that new buildings do not interfere with the recreational and protective functions of the natural system and that the buildings will be useful long enough to protect the investment are among long-term solutions to coastal erosion. We propose that coastal cliff management districts be established for management of eroding high relief shorelines. Such districts would include an imminent failure zone, in which bluff retreat is possible at any time; a migration zone, which allows for long-term shoreline retreat; and a stability control zone in which activities affecting bluff erosion are restricted. Procedures are described for delineating these zones based on geomorphic criteria. If these land use controls are implemented, some shorefront development can be accommodated while retaining valuable characteristics of the natural system.     

Volatilization and degradation of soil-applied dimethylselenide

Dimethylselenide (DMSe) is a highly volatile gas that is produced by indigenous microorganisms in seleniferous soils and sediments; however, little is known about the soil conditions that affect the persistence of DMSe and its transport to the atmosphere. In this study we investigated the effect of moisture content, temperature, and organic amendments on the degradation of soil-applied DMSe. The degradation of DMSe was entirely a result of biological mechanisms, but changes in temperature (20-40 degrees C) and soil moisture content (30-70% of the maximum water holding capacity) had little influence on the degradation rate. In contrast, amending soil with either 1% casein or gluten (by weight) had an inhibitory effect on the degradation of DMSe. After 18 d, 2.1 times more DMSe was present in the casein-amended soil and 2.6 times more DMSe was present in the gluten-amended soil. The transport of DMSe in packed soil columns was also investigated. Increasing the depth to soil surface was found to significantly decrease the amount of DMSe transported to the air. After 6 d, 57% of DMSe injected 10 cm below the soil surface was volatilized. At an injection depth of 20 cm the cumulative emissions were reduced by 38% and at 30 cm the cumulative emissions were reduced by 51%. In columns containing 1% casein or gluten in the top 5 cm of soil the cumulative loss of DMSe was about 9% higher than in unamended soil. Increasing our understanding of the soil conditions that influence the gaseous diffusion of DMSe should help in determining the feasibility of using Se volatilization as a remediation technique.     

Environmental photodegradation of mefenamic acid

Pharmaceuticals and personal care products are an emerging class of environmental pollutants. Photolysis is expected to be a major loss process for many of these compounds in surface waters, including the common non-steroidal anti-inflammatory drug mefenamic acid. The direct photolysis solar quantum yield of mefenamic acid was observed to be 1.5+/-0.3x10(-4). Significant photosensitization was observed in solutions of Suwanee River fulvic acid and Mississippi River water, as well as for the model photosensitization compounds 3'-methoxyacetophenone, 2-acetonaphthone and perinaphthenone. Quenching, sparging and light-filtering experiments suggested a direct reaction of mefenamic acid with excited triplet-state dissolved organic matter as the major photosensitization process. The persistence of the model photosensitizer suggests that the photosensitization by perinaphthenone occurs either by triplet-energy transfer or an electron transfer followed by rapid regeneration of the sensitizer. Due to its low quantum yield, the loss of mefenamic acid in sunlit natural waters is expected to depend on both direct and indirect photodegradation processes.     

Deriving fuel-based emission factor thresholds to interpret heavy-duty vehicle roadside plume measurements

Remote sensing devices have been used for decades to measure gaseous emissions from individual vehicles at the roadside. Systems have also been developed that entrain diluted exhaust and can also measure particulate matter (PM) emissions. In 2015, the California Air Resources Board (CARB) reported that 8% of in-field diesel particulate filters (DPF) on heavy-duty (HD) vehicles were malfunctioning and emitted about 70% of total diesel PM emissions from the DPF-equipped fleet. A new high-emitter problem in the heavy-duty vehicle fleet had emerged. Roadside exhaust plume measurements reflect a snapshot of real-world operation, typically lasting several seconds. In order to relate roadside plume measurements to laboratory emission tests, we analyzed carbon dioxide (CO₂), oxides of nitrogen (NO_X), and PM emissions collected from four HD vehicles during several driving cycles on a chassis dynamometer. We examined the fuel-based emission factors corresponding to possible exceedances of emission standards as a function of vehicle power. Our analysis suggests that a typical HD vehicle will exceed the model year (MY) 2010 emission standards (of 0.2 g NO_X/bhp-hr and 0.01 g PM/bhp-hr) by three times when fuel-based emission factors are 9.3 g NO_X/kg fuel and 0.11 g PM/kg using the roadside plume measurement approach. Reported limits correspond to 99% confidence levels, which were calculated using the detection uncertainty of emissions analyzers, accuracy of vehicle power calculations, and actual emissions variability of fixed operational parameters. The PM threshold was determined for acceleration events between 0.47 and 1.4 mph/sec only, and the NO_X threshold was derived from measurements where after-treatment temperature was above 200°C. Anticipating a growing interest in real-world driving emissions, widespread implementation of roadside exhaust plume measurements as a compliment to in-use vehicle programs may benefit from expanding this analysis to a larger sample of in-use HD vehicles.

Implications: Regulatory agencies, civil society, and the public at large have a growing interest in vehicle emission compliance in the real world. Leveraging roadside plume measurements to identify vehicles with malfunctioning emission control systems is emerging as a viable new and useful method to assess in-use performance. This work proposes fuel-based emission factor thresholds for PM and NOx that signify exceedances of emission standards on a work-specific basis by analyzing real-time emissions in the laboratory. These thresholds could be used to prescreen vehicles before roadside enforcement inspection or other inquiry, enhance and further develop emission inventories, and potentially develop new requirements for heavy-duty inspection and maintenance (I/M) programs, including but not limited to identifying vehicles for further testing.