CORRELATION OF SELECTED WELL WATER QUALITY PARAMETERS WITH SOIL AND AQUIFER HYDROLOGIC PROPERTIES1

ABSTRACT: The geographical distribution of well water specific electrical conductivity and nitrate levels in a 932 km² ground water quality study area in the Fresno-Clovis, California, indicated that frequently areas of lower ground water salinity were also areas of relatively greater soil and aquifer permeability. From these observations and certain assumptions we hypothesized that the quality of the well water should be better in areas with permeable soils and geological formations. Correlation and multiple linear regression analysis supported this hypothesis for well water salinity. However, well water nitrate levels were significantly negatively correlated with only the estimated equivalent specific yield of the aquifer system. The multiple R² values of the most significant multiple linear regression models showed that only a fourth to a third of the variability in well water specific electric conductivity and nitrate levels could be ascribed to the effects of the hydrogeological parameters considered with more than 90 percent confidence. This indicates that three-fourths to two-thirds of the variability in ground water salinity and nitrate levels may be related to land use. Thus, there is considerable room for land use management techniques to improve ground water quality and reduce its variability.     

Variations in surface functional groups, carbon chemical state and graphitization degree during thermal deactivation of diesel soot particles

The thermal deactivation of diesel soot particles exerts a significant influence on the control strategy for the regeneration of diesel particulate filters (DPFs). This work focused on the changes in the surface functional groups, carbon chemical state, and graphitization degree during thermal treatment in an inert gas environment at intermediate temperatures of 600°C, 800°C, and 1000°C and explore the chemical species that were desorbed from the diesel soot surface during thermal treatment using a thermogravimetric analyser coupled with a gas-chromatograph mass spectrometer (TGA-GC/MS). The surface functional groups and carbon chemical state were characterized using Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). The graphitization degree was evaluated by means of Raman spectroscopy (RS). The concentrations of aliphatic C–H, C–OH, C=O, and O–C=O groups are reduced for diesel soot and carbon black when increasing the thermal treatment temperature, while the sp²/sp³ hybridized ratio and graphitization degree enhance. These results provide comprehensive evidence of the decreased reactivity of soot samples. Among oxygenated functional groups, the percentage reduction during thermal treatment is the largest for the O–C=O groups owing to its worst thermodynamic stability. TGA-GC/MS results show that the aliphatic and aromatic chains and oxygenated species would be desorbed from the soot surface during 1000°C thermal treatment of diesel soot.     

Influence of a Large Herbivore Reintroduction on Plant Invasions and Community Composition in a California Grassland

Abstract:  Despite many successful reintroductions of large mammalian herbivores throughout the world, remarkably little attention has focused on how these actions affect native and exotic vegetation at reintroduction sites. One such herbivore is tule elk ( Cervus elaphus nannodes ), which was on the brink of extinction in the mid 1800s, but now has numerous stable populations due to intensive reintroduction efforts. Here, we summarize results from a 5-year exclosure experiment that explored the effects of tule elk on a coastal grassland in northern California. Elk significantly altered the species composition of this community; the response of annual species (dominated heavily by exotic taxa) was dramatically different from perennial species. Elk herbivory increased the abundance and aboveground biomass of native and exotic annuals, whereas it either had no effect on or caused significant decreases in perennials. Elk also decreased the cover of native shrubs, suggesting that these herbivores play an important role in maintaining open grasslands. In addition, elk significantly reduced the abundance and biomass of a highly invasive exotic grass , Holcus lanatus, which is a major problem in mesic perennial grasslands. Our results demonstrate that the successful reintroduction of a charismatic and long-extirpated mammal had extremely complex effects on the plant community, giving rise to both desirable and undesirable outcomes from a management perspective. We suspect that these kinds of opposing effects are not unique to tule elk and that land managers will frequently encounter them when dealing with reintroduced mammals.     

Formaldehyde oxidation on Pd/USY catalysts at room temperature: The effect of acid pretreatment on supports

The complete catalytic oxidation of formaldehyde (HCHO) to CO₂ and H₂O at room temperature is a green route for indoor HCHO removal. Zeolite is an excellent carrier material for HCHO oxidation due to its large surface area, intricate pores and high adsorption capacity. However, the zeolite-supported noble metal catalysts have currently shown relatively low activity especially at room temperature. In this work, we present a facile acid treatment strategy for zeolite catalysts to improve the hydroxyl concentration and further enhance their catalytic activity for HCHO oxidation. Activity tests illustrated that HCHO could be completely oxidized to CO₂ and H₂O at a nearly 100% conversion rate with a weight hourly space velocity (WHSV) of 150,000 mL/(g∙hr) at 25°C, when the support of Pd/USY catalysts was pretreated by hydrochloric acid with a concentration of 0.20 mol/L. The characterization results revealed that the active hydroxyl groups originated from the dealumination in the acid treatment play a key role in the HCHO oxidation reaction. The deduced reaction mechanism suggests that bridging hydroxyl groups may oxidize HCHO to dioxymethylene (DOM) species and terminal hydroxyl groups are responsible for the transformation of DOM groups to formate (HCOO) species.     

生态补偿过程动态演化机制及其稳定策略研究

生态补偿是通过调节相关方的利益关系,实现可持续利用生态系统服务的一种手段或制度安排。论文从微观维度对生态补偿问题进行研究,将生态补偿利益群体分为实施群和受益群,建立非对称演化博弈模型,分析各群体利益关系的复制动态、演化稳定策略和演化博弈系统的稳定性。结果表明:在"举报惩罚"制度存在的情况下,两群体间的演化博弈存在唯一的稳定均衡策略(保护、补偿),即实施群选择"保护"策略,受益群选择"补偿"策略,其中实施群决策主导系统稳定性;利益群体各决策选择的比重是稳定均衡策略的重要影响因素,增加实施群和受益群选择"保护"和"补偿"策略的比重,可加快稳定均衡策略的有效形成。     

Comparative effects of different maize straw returning modes on soil humus composition and humic acid structural characteristics in Northeast China

In order to evaluate the effects of different maize straw returning modes on humus composition and humic acid (HA) structural, a field experiment was designed to have five treatments, i.e. Treatment CK (no straw returned), Treatment EIS (straw incorporated evenly into the soil using the crashing-ridging technique), Treatment SP (straw plowed into the soil), Treatment SM (straw returned as mulch) and Treatment SG (straw returned as pellets). Our results showed that Treatment EIS significantly increased the content of soil organic carbon (SOC), soil humus substances (HEC), soil humic acid carbon (HAC) and fulvic acid carbon (FAC) by 27.8%, 47.6%, 63.3% and 33.8%, respectively, as compared with CK. Among all the straw returning treatments, Treatment EIS was the most significant in effect of increasing the content of HEC, HAC and FAC. Moreover, Treatment EIS altered the composition of humus more significantly than all the other treatments, by increasing the proportion of alkyl C and the ratio of aliphatic C/aromatic C. These results suggest that straw returning accelerated the accumulation of soil organic C and various components of humus, significantly improved the structure of soil HA, with the practice of EIS in particular.     

Cooperative signaling as a potential mechanism for cohesion in a gregarious sawfly larva, <Emphasis Type="Italic">Perga affinis</Emphasis>

During periods of travel or dispersive activities (e.g., foraging), group-living animals face the common challenge of maintaining a cohesive unit. At the basic level, this challenge is no different for vertebrates than it is for arthropods and is solved through communication. Gregarious larvae of the Australian sawfly, Perga affinis, communicate via vibrational signals. The most common signal, tapping, involves striking the substrate with the sclerotized tip of the abdomen. This study investigates the role of tapping as a mechanism of cohesion, specifically in situations between a separated larva and a group. As nomadic foragers that move daily to new feeding locations and readily coalesce with other colonies, the possibility of separation and potential re-aggregation arises regularly. Experiments demonstrated that tapping facilitates cohesion as groups responded to the tapping of lone larvae and did so preferentially over other larval behaviors. Additionally, separated larvae respond to tapping by the group through increased walking activity. It is also possible that they receive directional information from the group's vibratory signals, although visual cues may influence orientation as well. Tapping represents a cooperative signal and, as such, I investigated the level of investment of both parties in the communicative exchange. While individual larvae invested more in the exchange than the group, the exchange is analogous to the Raise-the-Stakes model of cooperation in that groups gradually increased their investment according to the cumulative time spent tapping by the lone larva. The mutual but asymmetrical benefits received through cooperation are discussed and compared with similar situations between parents and offspring. Not all larvae in the group participated equally, suggesting individual differences in signaling propensity or strategy.     

A Soft Systems Approach to Watershed Management: A Road Salt Case Study

Watershed management requires integration of social and ecological understanding. Participatory approaches to planning and management incorporate stakeholder knowledge and understanding. An action research strategy using focus groups with Michigan State University operations units helped generate a soft systems model of watershed impacts of organizational decision-making regarding road de-icing. The results reveal tensions and inconsistencies between the mission and operation of the institution. These tensions are exacerbated by inadequate communication among various elements of the campus watershed management system. The action research approach facilitated the researchers understanding of the complex institutional system and helped identify possible areas for making improvements. Specifically, the researchers were able to facilitate improvement in some linkages between scientists developing campus watershed models and the operations staff responsible for handling many of the inputs being modeled.     

Management Objective Importance in Fisheries: An Evaluation Using the Analytic Hierarchy Process (AHP)

In determining the importance of criteria in the management of fisheries, two key issues stand out—the definition of a succinct set of criteria and the determination of which interest groups play a defining role in the management development process. This is indeed the case for all natural resource management problems, and many other environmental problems as well. The analytic hierarchy process (AHP) provides an effective framework for such an analysis. The AHP is generally used to evaluate importance amongst criteria based on the concept of paired comparison. This paper considers the development of a representative criteria hierarchy, and uses data obtained from a pairwise comparison survey based on the UK fisheries of the English Channel to investigate priorities that exist among different interest groups in the fisheries. The implementation of the AHP in this application provides a useful tool for analysis of criteria amongst groups involved in the management process with diverse interests.     

中美两国汽车驾驶安全影响因素研究

影响汽车驾驶安全的各国道路交通系统以及驾驶员的驾驶行为等存在着差异性 ,许多差异可以通过统计数据的分析 ,或者其他定量研究方法获取 ,但仍然有许多影响驾驶安全的因素难以发现。笔者通过焦点团体座谈会的方法 ,从驾驶者的角度 ,搜集并分析了中美两国驾驶安全的主要影响因素 ,以及具有美国驾驶经历会对我国驾驶员有何影响。通过中美两国定性数据的对比分析 ,得出了主要影响因素 ,与此同时 ,通过问卷调查定量地分析了这些因素的严重程度。