COALBED METHANE PRODUCT WATER CHEMISTRY IN THREE WYOMING WATERSHEDS1

ABSTRACT: The Powder River Basin in Wyoming has become one of the most active areas of coalbed methane (CBM) development in the western United States. Extraction of methane from coalbeds requires pumping of aquifer water, which is called product water. Two to ten extraction wells are manifolded into one discharge point and product water is released into nearby unlined holding ponds. The objective of this study was to evaluate the chemistry, salinity, and sodicity of CBM product water at discharge points and associated holding ponds as a function of watershed. The product water samples from the discharge points and associated holding ponds were collected from the Cheyenne River (CHR), Belle Fourche River (BFR), and Little Powder River (LPR) watersheds during the summers of 1999 and 2000. These samples were analyzed for pH, electrical conductivity (EC), total dissolved solids (TDS), alkalinity, sodium (Na), calcium (Ca), magnesium (Mg), potassium (K), sulfate (SO₄^2‐), and chloride (C^1‐). From the chemical data, practical sodium adsorption ratio (SARp) and true sodium adsorption ratio (SARt) were calculated for the CBM discharge water and pond water. The pH, EC, TDS, alkalinity, Na, Ca, Mg, K, SARp, and SARt of CBM discharge water increased significantly moving north from the CHR watershed to the LPR watershed. CBM discharge water in associated holding ponds showed significant increases in EC, TDS, alkalinity, Na, K, SARp, and SARt moving north from the CHR to the LPR watershed. Within watersheds, the only significant change was an increase in pH from 7.21 to 8.26 between discharge points and holding ponds in the LPR watershed. However, the LPR and BFR exhibited larger changes in mean chemistry values in pH, salinity (EC, TDS), and sodicity (SAR) between CBM product water discharges and associated holding ponds than the CHR watershed. For instance, the mean EC and TDS of CBM product water in LPR increased from 1.93 to 2.09 dS/m, and froml,232 to 1,336 mg/L, respectively, between discharge and pond waters. The CHR exhibited no change in EC, TDS, Na, or SAR between discharge water and pond water. Also, while not statistically significant, mean alkalinity of CBM product water in BFR and LPR watersheds decreased from 9.81 to 8.01 meq/L and from 19.87 to 18.14 meq/L, respectively, between discharge and pond waters. The results of this study suggest that release of CBM product water onto the rangelands of BFR and LPR watersheds may precipitate calcium carbonate (CaCO₃) in soils, which in turn may decrease infiltration and increase runoff and erosion. Thus, use of CBM product water for irrigation in LPR and BFR watersheds may require careful planning based on water pH, EC, alkalinity, Na, and SAR, as well as local soil physical and chemical properties.     

SEDIMENT OXYGEN DEMAND IN THE ARROYO COLORADO RIVER1

ABSTRACT: The lower reaches of the Arroyo Colorado have historically failed to meet their use under subsection 303(b) of the U.S. Clean Water Act due to fecal coliform bacteria and low dissolved oxygen (DO). Fish kills, especially at the tidal confluence at the Port of Harlingen, Texas, have been reported. Oxygen demand from sediment (SOD) for a river typically has two states‐diffusion limited SOD (SOD) and potential SOD (pSOD), expressed when sediment is resuspended through increased flow or other disturbances. The objective of this research was to measure SOD in the Arroyo Colorado River in situ, estimate pSOD ex situ, and evaluate the relationship between SOD and the depositional environment. We measured SOD and pSOD in the Arroyo Colorado River at up to eight sites over three sampling events. We identified the sample sites based on a modified Rosgen geomorphic index for streambed stabilization. Sites with high sediment deposition potential had high SOD. The average values of SOD between sites were 0.62 g/m²/day (standard deviation 0.38 g/m²/day) and ranged from 0.13 to 1.2 g/m²/day. Potential SOD values ranged from as low as 19.2 to as high as 2,779 g/m³ sediment/ day. Potential SOD can serve as an indicator of the possible impact of SOD from resuspended sediment in stream systems.     

VARIATION FEATURES OF PRECIPITATION IN GUANGXI

VariationfeaturesofprecipitationinGuangxiUnevendistributionofprecipitationinareas　ByreasonofcomplexlandforminGuangxi,theprecipitationvariesindifferentregionsandisgenerallyabundantinthesouthandthenorth,littleinthemiddleregion;abundantintheeastandlittleinthewest;abundantinhillyareasandlittleintherivervalleysandbasins;abundantinwindwardslopesandlittleinleewardslopes;abundantincoastlandandlittleinis lands.Therearemainly 4 pluvialregionsand 2littlerainfallregions.The 4pluvialregionswithprecipitat…     

提高化学需氧量质控合格率的研究

大庆油田化工总厂废水中化学需氧量（COD）的测定采用库仑法。为了提高质控合格率，从人员素质、仪器设备、电级内液等9个方面分析寻找导致误差的主要影响因素并制定对策。同时对影响电极内液及消解的因素进行正交实验确定最佳条件。结果使库仑法质控合格率由90％提高到95％，测定38次标样全部合格。     

A Conceptual Framework for Selecting and Analyzing Stressor Data to Study Species Richness at Large Spatial Scales

/ In this paper we develop a conceptual framework for selectingstressor data and analyzing their relationship to geographic patterns ofspecies richness at large spatial scales. Aspects of climate and topography,which are not stressors per se, have been most strongly linked withgeographic patterns of species richness at large spatial scales (e.g.,continental to global scales). The adverse impact of stressors (e.g., habitatloss, pollution) on species has been demonstrated primarily on much smallerspatial scales. To date, there has been a lack of conceptual developmenton how to use stressor data to study geographic patterns of speciesrichness at large spatial scales.The framework we developed includes four components: (1) clarification of theterms stress and stressor and categorization of factors affecting speciesrichness into three groups-anthropogenic stressors, natural stressors, andnatural covariates; (2) synthesis of the existing hypotheses for explaininggeographic patterns of species richness to identify the scales over whichstressors and natural covariates influence species richness and to providesupporting evidence for these relationships through review of previousstudies; (3) identification of three criteria for selection of stressor andcovariate data sets: (a) inclusion of data sets from each of the threecategories identified in item 1, (b) inclusion of data sets representingdifferent aspects of each category, and (c) to the extent possible, analysisof data quality; and (4) identification of two approaches for examiningscale-dependent relationships among stressors, covariates, and patterns ofspecies richness-scaling-up and regression-tree analyses.Based on this framework, we propose 10 data sets as a minimum data base forexamining the effects of stressors and covariates on species richness atlarge spatial scales. These data sets include land cover, roads, wetlands(numbers and loss), exotic species, livestock grazing, surface water pH,pesticide application, climate (and weather), topography, and streams.KEY WORDS: Anthropogenic impacts; Biodiversity; Environmental gradients;Geographic information systems; Hierarchy     

A New Modus Operandi for the Agricultural Economics Profession

Agricultural economics has, until the 1990s, enjoyeda reputation for relevance and usefulness to theagri-food industry and policy-makers. Thatreputation has been jeopardized by a growinginfatuation with models and quantification, and aconcomitant underemphasis placed on many complexproblems and issues of society. An illustrativeexample is explored, using agriculturalactivity-related damage to the natural resourcebase, environment and ecology. Agriculturaleconomists are urged to respond by broadening theirterms of reference and joining forces with otherdisciplines.     

Specific Contributions of Politics,Economics, and Toxicology in Setting Socially Consensual Limit Values

/ Limit values are legal limits for the concentrations of substances in the environment. They must be agreed upon in a consensual procedure between science, economics/technology, and political forces. This is a crucial political precondition for their social acceptance. The arguments put forward to justify their expediency and numerical level are based not only on risk-benefit considerations but also on the aspect of the technical avoidability of direct and indirect exposure. The critical assessment of the direct benefit of specified exposures falls within the responsibility of economics/technology, whereas criteria for their potential adverse effects (direct and indirect) are provided by medicine/biochemistry and/or ecology. Within this concept, the avoidance of nonbeneficial-even if not openly adverse-exposure is the essential aim of environmental hygiene and should be promoted by politics/science. In general, society or segments thereof reject adverse, accept beneficial, and tolerate unavoidable exposure. Conflicts of interest arise when different groups of society simultaneously define a given exposure as being adverse, beneficial, and unavoidable. Therefore, from the viewpoint of society as a whole, an optimal exposure lies as far as reasonably achievable at a level lower than known or plausible adverse effect thresholds (as defined by toxicology or ecology). This optimal level of exposure must be determined using a transparent and, hence, public procedure.KEY WORDS: Legal limit values; Benefit threshold; Social acceptance; Social tolerability; Adverse effect threshold; Avoidable exposure; Tolerance threshold; Environmental hygiene     

Integration of Environmental Assessment into the Regional Development Planning Process of the Galilee

/ The Galilee region on the northern edge of Israel constitutes more than 15% of the state's territory, supplies more than half of its drinking water needs, and is an important recreational resource and destination for Israelis. One of the main objectives of the plan for the Galilee was to devise a regional physical and economic development strategy for the years 1992-2007 that would arrest the trend of emigration of its residents, attract newly arrived immigrants to the region, and at the same time protect natural resources and environmental quality. This paper is limited to discussion of the environmental aspects of the plan. It analyzes spatial concepts for distribution of projected population growth, evaluates environmental impacts of alternative plans, and proposes a decision-making framework and tools for minimizing natural resources loss from development at the local level. Assessment of potential environmental impacts generated quantitative data of natural resources areas. Application of the data in the plan evaluation stage showed that the alternative that concentrated most of the new development in central Galilee was the second-best choice environmentally, but was preferred as the best choice for overall qualities. The planning study offers an alternative environmental impact assessment (EIA) process to the one presently used in Israel by incorporating environmental considerations at the initial plan-making stage and not at the plan-approval stage. It demonstrated that in order to be effective, environmental assessment and land-use planning should be seen as one effort that is integrated from the start and in each stage of the plan-making process.KEY WORDS: Environmental assessment; Development planning; Galilee     

A Sensitivity Analysis of Nitrogen Losses from Dairy Farms

International attention has focused on agricultural production systems as non-point sources of pollution affecting the quality of streams, estuaries and ground water resources. The objective of the current study was to develop a model of nitrogen management on the dairy farm, and to perform sensitivity analyses in order to determine the relative importance of manipulating herd nutrition, manure management and crop selection in reducing nitrogen (N) losses from the farm. The importance of the method of N input to the farm (purchased feed, legume fixation, inorganic fertilizer, imported manure) was investigated, and the potential to reduce N losses from dairy farms was evaluated. Nitrogen balance equations were derived, and related efficiency coefficients were set to reference values representing common management practices. Total farm N efficiency (animal product N per N input), and N losses per product N were determined for different situations by solving the set of simultaneous equations. Improvements in animal diet and management that increase the conversion of feed N to animal product by 50% would increase total farm N efficiency by 48% and reduce N losses per product by 36 to 40%. In contrast, reducing losses from manure collection, storage and application to improve the percentage of manure N that becomes available in soil by 100% would only improve total farm N efficiency by 13% and reduce total N losses by 14%. Selecting crops and management that can use soil nutrients 50% more efficiently would improve total farm efficiency by up to 59% and reduce N losses by up to 41% depending on the predominant nitrogen sources to the farm. Legume production would reduce N losses per product compared with non-legumes. There was more than a five fold difference in N losses per animal product N between the most extreme scenarios suggesting considerable opportunity to reduce N losses from dairy farms.