The binding of arsenic in sediments of the heavily industrialised Port Kembla Harbour, NSW, Australia, has been investigated. Both dredge and core samples have been used to develop a sieving/sequential extraction (SE) procedure. Dredge samples included oxic surficial and deeper anoxic sediment. The main core sample analysed was 18 cm deep, sliced at 2 cm intervals. Sediment was sieved to three size ranges (<63 microm, 63-250 microm, >250 microm) and each of these was then subjected to a four step SE, sequentially solubilizing arsenic as ion exchangeable, 1 M HCl soluble, NH(2)OH.HCl soluble, and strong oxidising acid soluble. Concentrations of 50-500 mg As kg(-1) were found, elevated well above local background values. The core sample showed elevated concentrations of arsenic within the top 6-8 cm (300-500 mg As kg(-1)), relative to the deeper sediment (100-200 mg As kg(-1)). Substantial portions of the total arsenic present in the 0-8 cm sediments of core and dredge samples, were found to be soluble in 1 M pH 5 phosphate buffer or 1 M HCl. Arsenic in the lower 8-18 cm of the core displayed different solubility, the fourth stage SE strong acid digestion being required to solubilize >90% of the deep sediment arsenic. It appears that diagenesis had resulted in remobilisation of weakly bound arsenic with subsequent diffusion and deposition in surficial layers. Strong acid soluble arsenic present in deeper sediments has two possible origins: sedimented as strongly bound remaining untouched by diagenetic events, or subjected to diagenetic reactions such as pyritization, which lead to more stable crystalline forms of minerals. 相似文献
Mountain forest areas are key for providing a wide range of ecosystem services and are hot spots for land use change processes, in particular, increase in forest cover at the expense of mountain pastures and meadows. Mountain forest systems in eastern and western Europe have likely similar future socio-economic situations but significantly different socio-economic history. Using a scenario-based land use modelling approach (Dyna-CLUE framework) we model three scenarios (trend, liberalisation and self-sufficiency) of future land use in the Polish Carpathians and the Swiss Alps, focussing on forest cover change. We find that forest cover increase can be expected to continue in European mountainous regions under all likely scenarios, limited only by relatively strict policy interventions. Biophysical factors, rather than socio-economic ones, are key for defining the suitability for, and therefore likely locations of future forest cover, but land use legacy plays a very important role in the spatial patterns of future forest cover, particularly in eastern Europe.
Zink, Jason M., Gregory D. Jennings, and G. Alexander Price, 2012. Morphology Characteristics of Southern Appalachian Wilderness Streams. Journal of the American Water Resources Association (JAWRA) 48(4): 762‐773. DOI: 10.1111/j.1752‐1688.2012.00647.x Abstract: Watersheds without urbanization or impacts from logging are rare in the southern Appalachian Mountains. The Joyce Kilmer/Slickrock Wilderness of North Carolina and Tennessee contains 24 km2 of old‐growth forest, with the balance of the wilderness in a mature second‐growth forest. The watersheds of Little Santeetlah and Slickrock Creek are located within the wilderness. Morphological information, including channel dimensions and longitudinal profiles, was gathered from 14 alluvial stream reaches in these watersheds. The study sites had drainage areas from 0.25 to 41.6 km2 and stream slopes from 0.014 to 0.104 m/m. Bankfull cross‐section dimensions of the study stream reaches were strongly correlated to drainage area across the observed range of slopes and bed morphology. Cross‐section area and width relationships for the streams in this study did not differ significantly from regional curves for the mountain physiographic region of North Carolina. Observations of these reaches did not suggest a definitive rule regarding the proportion of steps and riffles in streams. Pools occupied greater than 50% of the length in all stream reaches with slopes less than 0.07 m/m. Significant correlation existed between step height ratio and slope, suggesting that step height can be approximated as the product of channel width and slope. Riffle length and riffle slope ratios were also significantly correlated with slope, though pool spacing was not. 相似文献
The Afton Copper Smelter adjacent to Kamloops, British Columbia, Canada commenced operation in 1978 and employed a mercury scrubbing system. Two years of preproduction studies, which included monitoring for mercury in ambient air, water, soli, and vegetation were performed. The results from similar studies conducted during four full years (1978–81) and two partial years (1982–83) of production are presented in the data analysis. These programs illustrated that the most frequent ground impingement occurred within a 1.6–3.2- km radius of the source, and that the levels decreased with increasing distance from the source to a maximum radius of 8 km. The results of a comprehensive source monitoring program illustrated that the average mercury emission levels ranged from 3.2 to 6.8 kg/calendar day during 1979–81, and that the majority of the emissions were in a vapour form. The ambient monitoring data acquired when smelter operations were significantly reduced indicate a quick recovery to preproduction levels in virtually all monitored parameters and at most monitored sites. The integrated results from all mercury monitoring programs illustrate the environmental impact from mercury emissions which were two to four times the permit standard of 1.8 kg/day. 相似文献
Papermill biosolids (PB) can provide multiple benefits to the soil system. The purpose of this study was to quantify the effects of a high C/N ratio (C/N = 100) de-inked PB on soil physical and chemical properties, including soil bulk density, infiltration rates, wet aggregate stability, total soil carbon, and heavy metal concentrations. Four rates of PB (0, 50, 100, and 150 Mg ha(-1)) were applied annually, for up to 3 yr, on four agricultural soils in Ontario, Canada. Decreases in soil bulk density between 0.27 and 0.35 g cm(-3), relative to the nonamended treatment, were observed in soils receiving PB treatments over 3 yr. Total soil carbon increased within 1 yr on PB-amended soils planted to soybeans but not on soils planted to corn. Hydraulic conductivities (K fs) were greater in all soils receiving PB amendments relative to the nonamended treatment throughout the study. Other properties measured, such as pH and electrical conductivity, were relatively unchanged after 2 yr of PB applications. While some increases in heavy metal accumulation occurred, there were no clear trends observed at any of the sites related to PB rates. The results of this study provide support to the idea that annual applications of PB can add significantly to the stability of soil structure. 相似文献
This paper reviews the evolution of energy use in Denmark since the early 1970s, in order to shed light on the future path of energy use in Denmark, with particular emphasis on the role of energy efficiency. Improvements in end-use energy efficiency reduced primary energy requirements in Denmark by 22% between 1972 and 1988. This change accounts for two-thirds of the decline in the ratio of energy use to gross domestic product that occurred during this time: the rest of the decline was caused by changes in the mix of goods and services produced and consumed by the Danes. Total energy savings achieved between 1972 and 1988 in Denmark ranked among the highest measured in any major OECD country. Overall, most of the energy savings in Denmark were brought about through improvements in technology. Short-term changes in consumer behaviour were significant in reducing energy needs for space heating and transport. An important stimulus for improved efficiency was higher energy prices, led in no small part by significant taxes imposed on small consumers of heating oil, electricity and motor fuels. 相似文献
Management strategies to reduce the risks to human life and property from wildfire commonly involve burning native vegetation. However, planned burning can conflict with other societal objectives such as human health and biodiversity conservation. These conflicts are likely to intensify as fire regimes change under future climates and as growing human populations encroach farther into fire‐prone ecosystems. Decisions about managing fire risks are therefore complex and warrant more sophisticated approaches than are typically used. We applied a multicriteria decision making approach (MCDA) with the potential to improve fire management outcomes to the case of a highly populated, biodiverse, and flammable wildland–urban interface. We considered the effects of 22 planned burning options on 8 objectives: house protection, maximizing water quality, minimizing carbon emissions and impacts on human health, and minimizing declines of 5 distinct species types. The MCDA identified a small number of management options (burning forest adjacent to houses) that performed well for most objectives, but not for one species type (arboreal mammal) or for water quality. Although MCDA made the conflict between objectives explicit, resolution of the problem depended on the weighting assigned to each objective. Additive weighting of criteria traded off the arboreal mammal and water quality objectives for other objectives. Multiplicative weighting identified scenarios that avoided poor outcomes for any objective, which is important for avoiding potentially irreversible biodiversity losses. To distinguish reliably among management options, future work should focus on reducing uncertainty in outcomes across a range of objectives. Considering management actions that have more predictable outcomes than landscape fuel management will be important. We found that, where data were adequate, an MCDA can support decision making in the complex and often conflicted area of fire management. 相似文献
The existence of deterministic assembly rules for plant communities remains an important and unresolved topic in ecology. Most studies examining community assembly have sampled aboveground species diversity and composition. However, plants also coexist belowground, and many coexistence theories invoke belowground competition as an explanation for aboveground patterns. We used next-generation sequencing that enables the identification of roots and rhizomes from mixed-species samples to measure coexisting species at small scales in temperate grasslands. We used comparable data from above (conventional methods) and below (molecular techniques) the soil surface (0.1 x 0.1 x 0.1 m volume). To detect evidence for nonrandom patterns in the direction of biotic or abiotic assembly processes, we used three assembly rules tests (richness variance, guild proportionality, and species co-occurrence indices) as well as pairwise association tests. We found support for biotic assembly rules aboveground, with lower variance in species richness than expected and more negative species associations. Belowground plant communities were structured more by abiotic processes, with greater variability in richness and guild proportionality than expected. Belowground assembly is largely driven by abiotic processes, with little evidence for competition-driven assembly, and this has implications for plant coexistence theories that are based on competition for soil resources. 相似文献
Rats excreted the 14C from a single oral dose of N-isopropyl-N-[14C]phenyloxamic acid [I, a soil metabolite from 2-chloro-N-isopropylacetanilide (propachlor)] in approximately equal quantities in the urine (49.2%) and feces (48.2%). A milking goat given daily oral doses of [14C]-I (1 mg of I three times daily) excreted more 14C in the feces (56.6%) than it excreted in the urine. From both species, I accounted for 97 to 100% of the urinary 14C, and all of the 14C that was extractable from the feces (73 to 75% of the 14C in feces was extractable with methanol). Goat milk samples collected 16 hr after the last dose contained no detectable 14C. Tissue residues of 14C were determined. 相似文献