咸阳市单位GDP能耗空间分异特征分析研究

以地统分析为基础,在GIS技术平台下分析"十一五"期间咸阳市各区县单位GDP能耗空间分异特征.单位GDP能耗重心与几何中心偏移较大,在西北-东南向最为分散,不均衡性大;全局相关性属随机分布模式,自相关性一般,局部相关性呈区域性分布,具有较强相关性的区域为东南方向的泾阳和三原县、西北方向的彬县和长武县;微弱相关性区域主要分布在旬邑县、咸阳中南部地区;5年间单位GDP能耗重心向西北方向偏移,向高纬度、低经度方向移动.     

Sulphate toxicity to the aquatic moss, Fontinalis antipyretica

The aquatic moss, Fontinalis antipyretica was exposed to elevated sulphate concentrations for 21-days. Gametophores were sectioned to 2 cm lengths and exposed to sulphate concentrations up to 1500 mg/l, in waters of different water hardness. Significant reductions in shoot length, dry weight, and chlorophyll a and b concentrations (per gram dry weight) were observed in soft water (19 mg/l as CaCO3); however, effects were significantly reduced in waters of increasing hardness (up to 105 mg/l as CaCO3). The substantial reduction of sulphate toxicity in waters of increasing hardness suggests water chemistry plays a significant role in affecting sulphate toxicity and should be considered when setting sulphate discharge limits.     

Application of Genetic Bottleneck Testing to the Investigation of Amphibian Declines: a Case Study with Natterjack Toads

Abstract: Declines of amphibians are causing widespread concern and in some cases have been explained by factors such as climate change and the spread of microbial pathogens. A problem remains, however, in the unequivocal demonstration of decline in situations where populations may be undergoing natural fluctuations in abundance. We describe the application of a genetic test for bottlenecks ( Cornuet & Luikart 1996 ) that should distinguish between natural oscillations and true population declines. British natterjack toads (   Bufo calamita  ) provide examples of populations that have not declined in recent decades, populations that have declined, and populations in which trends are unclear. Microsatellite allele frequency data from these populations were tested for heterozygote excess and shifts in allele frequency distributions, and inferences from these computations about bottlenecks (i.e., persistently smaller population sizes than the recent means) were compared with demographic information. The genetic test correctly identified bottlenecks and should therefore prove useful in demonstrating whether amphibian declines have occurred where long-term demographic time series are not available.     

Modelling the closure-related geochemical evolution of groundwater at a former uranium mine

A newly developed reactive transport model was used to evaluate the potential effects of mine closure on the geochemical evolution in the aquifer downgradient from a mine site. The simulations were conducted for the K?nigstein uranium mine located in Saxony, Germany. During decades of operation, uranium at the former mine site had been extracted by in situ acid leaching of the ore underground, while the mine was maintained in a dewatered condition. One option for decommissioning is to allow the groundwater level to rise to its natural level, flooding the mine workings. As a result, pore water containing high concentrations of dissolved metals, radionuclides, and sulfate may be released. Additional contamination may arise due to the dissolution of minerals contained in the aquifer downgradient of the mine. On the other hand, dissolved metals may be attenuated by reactions within the aquifer. The geochemical processes and interactions involved are highly non-linear and their impact on the quality of the groundwater and surface water downstream of the mine is not always intuitive. The multicomponent reactive transport model MIN3P, which can describe mineral dissolution-precipitation reactions, aqueous complexation, and oxidation-reduction reactions, is shown to be a powerful tool for investigating these processes. The predictive capabilities of the model are, however, limited by the availability of key geochemical parameters such as the presence and quantities of primary and secondary mineral phases. Under these conditions, the model can provide valuable insight by means of sensitivity analyses.     

Community-led reforestation: cultivating the potential of virtuous cycles to confer resilience in disaster disrupted social–ecological systems

Human relationships with trees can result in widespread citizen-led reforestation projects that catalyze social–biological-reinforcing feedback loops and set in motion virtuous cycles that restore perturbed social–ecological systems. These virtuous cycles confer resilience in such systems that counterbalance the tendency for vicious cycles to be triggered by destructive behavior and neglect. Given this argument, we ask: how do we cultivate the potential for virtuous cycles to confer resilience in social–ecological systems? To answer this question, we review feedback mechanisms and identify virtuous cycles catalyzed via ecological restoration to highlight their importance to the resilience of social–ecological systems. We then conceptualize these cycles with a causal map (also known as a causal loop diagram) illustrating an example where restoration activities and civic ecology practices contributed to feedbacks and virtuous cycles. Following from this example, we discuss approaches for recognizing and investing in virtuous cycles that accompany social–ecological systems and outline approaches for managing such cycles.     

Characterization and optimization of an online system for the simultaneous measurement of atmospheric water-soluble constituents in the gas and particle phases

In this work we present the results of extensive characterization and optimization of the Ambient Ion Monitor-Ion Chromatograph (AIM-IC) system, an instrument developed by URG Corp. and Dionex Inc. for simultaneous hourly measurements of the water-soluble chemical composition of atmospheric fine particulate matter (PM(2.5)) and associated precursor gases. The sampling assembly of the AIM-IC consists of an inertial particle size-selection assembly, a parallel-plate wet denuder (PPWD) for the collection of soluble gases, and a particle supersaturation chamber (PSSC) for collection of particles, in series. The analytical assembly of the AIM-IC consists of anion and cation IC units. The system detection limits were determined to be 41 ppt, 5 ppt, and 65 ppt for gas phase NH(3(g)), SO(2(g)), and HNO(3(g)) and 29 ng m(-3), 3 ng m(-3), and 45 ng m(-3) for particle phase NH(4)(+), SO(4)(2-), and NO(3)(-) respectively. From external trace gas calibrations with permeation sources, we determined that the AIM-IC is biased low for NH(3(g)) (11%), SO(2(g)) (19%), and HNO(3(g)) (12%). The collection efficiency of SO(2(g)) was found to strongly depend on the composition of the denuder solution and was found to be the most quantitative with 5 mM H(2)O(2) solution for mixing ratios as high as 107 ppb. Using a cellulose membrane in the PPWD, the system responded to changes in SO(2(g)) and HNO(3(g)) within an hour, however for NH(3(g)), the timescale can be closer to 20 h. With a nylon membrane, the instrument response time for NH(3(g)) was significantly improved, becoming comparable to the responses for SO(2(g)) and HNO(3(g)). Performance of the AIM-IC for collection and analysis of PM(2.5) was evaluated by generating known number concentrations of ammonium sulfate and ammonium nitrate particles (with an aerodynamic diameter of 300 nm) under laboratory conditions and by comparing AIM-IC measurements to measurements from a collocated Aerosol Mass Spectrometer (AMS) during a field-sampling campaign. On average, the AIM-IC and AMS measurements agreed well and captured rapid ambient concentration changes at the same time. In this work we also present a novel inlet configuration and plumbing for the AIM-IC which minimizes sampling inlet losses, reduces peak smearing due to sample carryover, and allows for tower-height sampling from the base of a research tower.     

Effect on herbicide adsorption of organic forestry waste products used for soil remediation

Organic soil amendments can be useful for improving degraded soil, but this increase in organic matter (OM) may influence adsorption of herbicides subsequently applied to the treated soil, even though the particle size of amendments and their nature differ from typical soil OM. In this study, a batch equilibrium method was used to measure adsorption of five herbicides following application to two organic media, wood pulp and sawdust, comparing these with two cropping soils. Herbicide adsorption, quantified by distribution coefficients (k_d), was much higher in the two organic media than in the cropping soils. The increases in adsorption were strongly correlated to the percentage of organic carbon. When the k_d was normalized to adsorption coefficients corrected for OM content (k_oc), variation in results between the media was greatly reduced, indicating that OM is an important factor influencing adsorption in these media. The results of this study suggest that herbicides will be less effective when applied to soils in which sawdust and wood pulp have been added. Using organic amendments to remediate soil will increase adsorption of pesticides, reducing their bio-availability and efficacy, but also reducing their tendency to leach into root zones of deep-rooted crops and into groundwater.     

Alkyl nitrate photochemistry during the tropospheric organic chemistry experiment

Alkyl nitrates (C₁–C₅) were measured at two sites (near urban and rural) in southeast England during the Tropospheric Organic Chemistry Experiment (TORCH). Methyl nitrate was the dominant species during both campaigns accounting for on average about one third of the total measured alkyl nitrates. High mixing ratios (>50 pptv) and variability of methyl nitrate were observed at the near urban site (TORCH1) that were not seen at the rural site (TORCH2) and which could not be explained by local photochemical production or direct emissions. The diurnal variation of methyl nitrate during TORCH1 showed a morning maximum that would be consistent with nighttime chemistry followed by transport to the surface by boundary layer dynamics. Similarly, elevated morning mixing ratios were also observed during TORCH2 although the magnitudes were much smaller. As a result, methyl nitrate could represent a tracer for nighttime chemistry seen at the ground the following day. At both campaigns, the dominant source of short chain alkyl nitrates and carbonyl precursor radicals (≤C₄) were from decomposition of larger compounds. The magnitude of the source increased with decreasing carbon number consistent with increasing total precursor abundance. Non-photochemical emissions of acetaldehyde and acetone could not be accounted for by automobile exhaust emissions alone and indicated that other direct sources are likely important in this environment.