A COMPARISON OF DELTA CHANGE AND DOWNSCALED GCM SCENARIOS FOR THREE MOUNTAINOUS BASINS IN THE UNITED STATES1

ABSTRACT: Simulated daily precipitation, temperature, and runoff time series were compared in three mountainous basins in the United States: (1) the Animas River basin in Colorado, (2) the East Fork of the Carson River basin in Nevada and California, and (3) the Cle Elum River basin in Washington State. Two methods of climate scenario generation were compared: delta change and statistical downscaling. The delta change method uses differences between simulated current and future climate conditions from the Hadley Centre for Climate Prediction and Research (HadCM2) General Circulation Model (GCM) added to observed time series of climate variables. A statistical downscaling (SDS) model was developed for each basin using station data and output from the National Center for Environmental Prediction/National Center for Atmospheric Research (NCEPINCAR) reanalysis regridded to the scale of HadCM2. The SDS model was then used to simulate local climate variables using HadCM2 output for current and future conditions. Surface climate variables from each scenario were used in a precipitation‐runoff model. Results from this study show that, in the basins tested, a precipitation‐runoff model can simulate realistic runoff series for current conditions using statistically down‐scaled NCEP output. But, use of downscaled HadCM2 output for current or future climate assessments are questionable because the GCM does not produce accurate estimates of the surface variables needed for runoff in these regions. Given the uncertainties in the GCMs ability to simulate current conditions based on either the delta change or downscaling approaches, future climate assessments based on either of these approaches must be treated with caution.     

NUTRIENT LOAD CHARACTERIZATION FROM INTEGRATED SOURCE DATA FOR THE LOWER MISSISSIPPI RWER1

ABSTRACT: Nutrient data from all available sources for the lower Mississippi River were examined for potential differences among sampling agencies and geographic locations for the period between 1960 and 1998. Monthly means grouped by parameter, sampling location and agency, were calculated and compared as paired sets, excluding those months where data were not available for both sets. Some significant differences were found between various agencies collecting nutrient data on the river, as well as between various stretches of river, especially in the case of phosphorus nutrient data. Results were used to synthesize data sets from which a history of nutrient loading in the Mississippi River was determined. General trends in nitrate+nitrite, total Kjeldahl nitrogen, orthophosphate, total phosphorus and silica loads, as well as changes in nutrient proportions and the specific limiting nutrient (by month) are reported. This study provides a useful summary of contemporary and historical nutrient data that may assist in the evaluation of Mississippi River water quality and its potential effect on the Gulf of Mexico.     

Comparison of quartz sand, anthracite, shale and biological ceramsite for adsorptive removal of phosphorus from aqueous solution

The choice of substrates with high phosphorus adsorption capacity is vital for sustainable phosphorus removal from waste water in constructed wetlands. In this study, four substrates were used： quartz sand, anthracite, shale and biological ceramsite. These substrate samples were characterized by X- ray diffractometry and scanning electron microscopy studies for their mineral components （chemical components） and surface characteristics. The dynamic experimental results revealed the following ranking order for total phosphorus （TP） removal efficiency： anthracite 〉 biological ceramsite 〉 shale 〉 quartz sand. The adsorptive removal capacities for TP using anthracite, biological ceramsite, shale and quartz sand were 85.87, 81.44, 59.65, and 55.98 mg/kg, respectively. Phosphorus desorption was also studied to analyze the substrates＇ adsorption efficiency in wastewater treatment as well as the substrates＇ ability to be reused for treatment. It was noted that the removal performance for the different forms of phosphorus was dependent on the nature of the substrate and the adsorption mechanism. A comparative analysis showed that the removal of particulate phosphorus was much easier using shale. Whereas anthracite had the highest soluble reactive phosphorus （SRP） adsorptive capacity, biological ceramsite had the highest dissolved organic phosphorus （DOP） removal capacity. Phosphorus removal by shale and biological ceramsite was mainly through chemical adsorption, precipitation or biological adsorption. On the other hand, phosphorus removal through physical adsorption （electrostatic attraction or ion exchange） was dominant in anthracite and quartz sand.     

Multiple regression models: a methodology for evaluating trihalomethane concentrations in drinking water from raw water characteristics

The presence of trihalomethanes (THMs) in drinking water has attracted the attention of both researchers and professionals, because of the harmful effects of these substances on human health. A multiple regression model was developed to estimate THM concentrations in finished drinking water, using data from the Menidi Treatment Plant of Athens. A number of routinely measured characteristics--including chlorine dose, chlorophyll a, temperature, pH and bromide--of raw water, were used to generate a reliable methodology for predicting both total THM and individual species concentrations. Seasonality effects were also considered during the analysis. In general, these models were found to give acceptable fits, estimating accurately lows and highs over the annual cycle.     

离子交换树脂静态吸附二甲胺的研究

通过静态吸附实验,研究了二甲胺在ZGSPC106型细颗粒树脂上的吸附行为,从热力学和动力学角度对吸附过程进行了分析,并用红外光谱的方法探讨了树脂吸附二甲胺的机理.结果表明,Langmuir等温方程能够很好的拟合吸附平衡数据,热力学参数表明该吸附可自发进行,且为熵增加的吸热过程,293K温度下树脂的静态饱和吸附容量为138.89mg/g(干树脂);吸附动力学符合准二级动力学模型,颗粒扩散是树脂吸附二甲胺速率的主要控制步骤.     

Efficacy of extracting indices from large‐scale acoustic recordings to monitor biodiversity

Passive acoustic monitoring could be a powerful way to assess biodiversity across large spatial and temporal scales. However, extracting meaningful information from recordings can be prohibitively time consuming. Acoustic indices (i.e., a mathematical summary of acoustic energy) offer a relatively rapid method for processing acoustic data and are increasingly used to characterize biological communities. We examined the relationship between acoustic indices and the diversity and abundance of biological sounds in recordings. We reviewed the acoustic‐index literature and found that over 60 indices have been applied to a range of objectives with varying success. We used 36 of the most indicative indices to develop a predictive model of the diversity of animal sounds in recordings. Acoustic data were collected at 43 sites in temperate terrestrial and tropical marine habitats across the continental United States. For terrestrial recordings, random‐forest models with a suite of acoustic indices as covariates predicted Shannon diversity, richness, and total number of biological sounds with high accuracy (R² ≥ 0.94, mean squared error [MSE] ≤170.2). Among the indices assessed, roughness, acoustic activity, and acoustic richness contributed most to the predictive ability of models. Performance of index models was negatively affected by insect, weather, and anthropogenic sounds. For marine recordings, random‐forest models poorly predicted Shannon diversity, richness, and total number of biological sounds (R² ≤ 0.40, MSE ≥ 195). Our results suggest that using a combination of relevant acoustic indices in a flexible model can accurately predict the diversity of biological sounds in temperate terrestrial acoustic recordings. Thus, acoustic approaches could be an important contribution to biodiversity monitoring in some habitats.     

Perceived barriers to and drivers of community participation in protected‐area governance

Protected areas (PAs) are a frequently used conservation strategy, yet their socioeconomic impacts on local communities remain contentious. A shift toward increased participation by local communities in PA governance seeks to deliver benefits for human well‐being and biodiversity. Although participation is considered critical to the success of PAs, few researchers have investigated individuals’ decisions to participate and what this means for how local people experience the costs and benefits of conservation. We explored who participates in PA governance associations and why; the perceived benefits and costs to participation; and how costs and benefits are distributed within and between communities. Methods included 3 focus groups, 37 interviews, and 217 questionnaire surveys conducted in 3 communities and other stakeholders (e.g., employees of a nongovernmental organization and government officials) in PA governance in Madagascar. Our study design was grounded in the theory of planned behavior (TPB), the most commonly applied behavior model in social psychology. Participation in PA governance was limited by miscommunication and lack of knowledge about who could get involved and how. Respondents perceived limited benefits and high costs and uneven distribution of these within and between communities. Men, poorer households, and people in remote villages reported the highest costs. Our findings illustrate challenges related to comanagement of PAs: understanding the heterogeneous nature of communities; ensuring all households are represented in governance participation; understanding differences in the meaning of forest protection; and targeting interventions to reach households most in need to avoid elite capture.     

Treatability studies as a remedial option screening tool for contaminated soils

As the limitations of site remedial technologies become more apparent and greater experience in their field implementation and effectiveness is gained, increased emphasis is placed on development of a structured technology selection process. Ideally, this selection process should yield the most cost-effective technology, which will accomplish cleanup goals in the shortest time frame. Although laboratory treatability studies comprise an essential component of this process, very little has been written about the methodology of designing, executing, and assessing the value of their results. This article presents practical considerations for environmental professionals who use treatability results in technology selection or others who execute such studies.     

When is a Life Too Costly to Save? The Evidence from U.S. Environmental Regulations

Under certain environmental statutes the EPA is required to balance costs and benefits in setting standards, whereas under others this is prohibited. This paper examines EPA regulatory decisions made under three statues, two of which require balancing and one of which does not. Using discrete choice models, we find that costs and benefits are significant explanatory variables for all three sets of decisions. This suggests that balancing occurred in each case; however, the value (implicit in these decisions) of avoiding a cancer case varies widely. We also find that a 1987 court ruling effectively curtailed whatever balancing occurred under the statute that prohibited it.     

BUFFER STRIPS TO PROTECT WATER SUPPLY RESERVOIRS: A MODEL AND RECOMMENDATIONS1

ABSTRACT: Buffer strips are undisturbed, naturally vegetated zones around water supply reservoirs and their tributaries that are a recognized and integral aspect of watershed management. These strips can be very effective in protecting the quality of public potable water supply reservoirs by removing sediment and associated pollutants, reducing bank erosion, and displacing activities from the water's edge that represent potential sources of nonpoint source pollutant generation. As part of a comprehensive watershed management protect for the State of New Jersey, a parameter-based buffer strip model was developed for application to all watersheds above water supply intakes or reservoirs. Input requirements for the model include a combination of slope, width, and time of travel. The application of the model to a watershed in New Jersey with a recommended buffer strip width that ranges from 50 to 300 feet, depending upon a number of assumptions, results in from 6 to 13 percent of the watershed above the reservoir being occupied by the buffer.