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961.
Quantifying the Effects of Conservation Practices on Soil,Water, and Nutrients in the Loess Mesa Ravine Region of the Loess Plateau,China 总被引:1,自引:0,他引:1
A large number of soil and water conservation programs have been implemented on the Loess Plateau of China since the 1950s.
To comprehensively assess the merits and demerits of the conservation practices is of great importance in further supervising
the conservation strategy for the Loess Plateau. This study calculates the impact factors of conservation practices on soil,
water, and nutrients during the period 1954–2004 in the Nanxiaohegou Catchment, a representative catchment in the Loess Mesa
Ravine Region of the Loess Plateau, China. Brief conclusions could be drawn as follows: (1) Soil erosion and nutrient loss
had been greatly mitigated through various conservation practices. About half of the total transported water and 94.8 % of
the total transported soil and nutrients, had been locally retained in the selected catchment. The soil retained from small
watersheds do not only form large-scale fertile farmland but also safeguard the Yellow River against overflow. (2) Check dam
was the most appropriate conservation practice on the Loess Plateau. In the selected catchment, more than 90 % of the retained
soil and water were accomplished by the dam farmland, although the dam farmland occupied only 2.3 % of the total area of all
conservation measures. Retention abilities of the characteristic conservation practices were in the following order: dam farmland > terrace
farmland > forest land and grassland. (3) The conservation practices were more powerful in retaining sediment than in reducing
runoff from the Loess Plateau, and the negative effects of the conservation practices on reducing water to the Yellow River
were relatively slight. 相似文献
962.
Management of forests, rangelands, and wetlands on public lands, including the restoration of degraded lands, has the potential
to increase carbon sequestration or reduce greenhouse gas (GHG) emissions beyond what is occurring today. In this paper we
discuss several policy options for increasing GHG mitigation on public lands. These range from an extension of current policy
by generating supplemental mitigation on public lands in an effort to meet national emissions reduction goals, to full participation
in an offsets market by allowing GHG mitigation on public lands to be sold as offsets either by the overseeing agency or by
private contractors. To help place these policy options in context, we briefly review the literature on GHG mitigation and
public lands to examine the potential for enhanced mitigation on federal and state public lands in the United States. This
potential will be tempered by consideration of the tradeoffs with other uses of public lands, the needs for climate change
adaptation, and the effects on other ecosystem services. 相似文献
963.
Dearing JA Bullock S Costanza R Dawson TP Edwards ME Poppy GM Smith GM 《Environmental management》2012,49(4):767-775
The ‘Perfect Storm’ metaphor describes a combination of events that causes a surprising or dramatic impact. It lends an evolutionary
perspective to how social-ecological interactions change. Thus, we argue that an improved understanding of how social-ecological
systems have evolved up to the present is necessary for the modelling, understanding and anticipation of current and future
social-ecological systems. Here we consider the implications of an evolutionary perspective for designing research approaches.
One desirable approach is the creation of multi-decadal records produced by integrating palaeoenvironmental, instrument and
documentary sources at multiple spatial scales. We also consider the potential for improved analytical and modelling approaches
by developing system dynamical, cellular and agent-based models, observing complex behaviour in social-ecological systems
against which to test systems dynamical theory, and drawing better lessons from history. Alongside these is the need to find
more appropriate ways to communicate complex systems, risk and uncertainty to the public and to policy-makers. 相似文献
964.
The present study was conducted to compare the 137Cs, 40K, 232Th, and 238U activity concentrations in epigeic moss (Hypnum cupressiforme) and lichen (Cladonia rangiformis). The activity levels in 37 moss and 38 lichen samples collected from the Marmara region of Turkey were measured using a gamma spectrometer equipped with a high purity germanium (HPGe) detector. The activity concentrations of 137Cs, 40K, 232Th, and 238U in the moss samples were found to be in the range of 0.36-8.13, 17.1-181.1, 1.51-6.17, and 0.87-6.70 Bq kg−1 respectively, while these values were below detection limit (BDL)-4.32, 16.6-240.0, 1.32-6.47, and BDL-3.57 Bq kg−1 respectively in lichen. The average moss/lichen activity ratios of 137Cs, 40K, 232Th, and 238U were found to be 1.32 ± 0.57, 2.79 ± 1.67, 2.11 ± 0.82, and 2.19 ± 1.02, respectively. Very low 137Cs concentrations were observed in moss and lichen samples compared to soil samples collected from the same locations in a previous study. Seasonal variations of the measured radionuclide activities were also examined in the three sampling stations. 相似文献
965.
John S. Kinsey Yuanji Dong D. Craig Williams Russell Logan 《Atmospheric environment (Oxford, England : 1994)》2010,44(17):2147-2156
The fine particulate matter (PM) emissions from nine commercial aircraft engine models were determined by plume sampling during the three field campaigns of the Aircraft Particle Emissions Experiment (APEX). Ground-based measurements were made primarily at 30 m behind the engine for PM mass and number concentration, particle size distribution, and total volatile matter using both time-integrated and continuous sampling techniques. The experimental results showed a PM mass emission index (EI) ranging from 10 to 550 mg kg?1 fuel depending on engine type and test parameters as well as a characteristic U-shaped curve of the mass EI with increasing fuel flow for the turbofan engines tested. Also, the Teflon filter sampling indicated that ~40–80% of the total PM mass on a test-average basis was comprised of volatile matter (sulfur and organics) for most engines sampled. The number EIs, on the other hand, varied from ~1015 to 1017 particles kg?1 fuel with the turbofan engines exhibiting a logarithmic decay with increasing fuel flow. Finally, the particle size distributions of the emissions exhibited a single primary mode that were lognormally distributed with a minor accumulation mode also observed at higher powers for all engines tested. The geometric (number) mean particle diameter ranged from 9.4 to 37 nm and the geometric standard deviation ranged from 1.3 to 2.3 depending on engine type, fuel flow, and test conditions. 相似文献
966.
This research investigated the under-explored area of safety in multi-purpose recreation facilities (MPRFs). Facility managers and other managerial staff (key informants) from four MPRFs in Victoria, Australia participated in semi-structured interviews. Safety was considered important from Occupational Health and Safety (OH&S), business viability and legal liability perspectives but not from a health promotion or public health point of view. Most implemented injury prevention measures required gymnasium and pool staff or users to change their behaviours. Awareness of safety standards was higher for some operational areas (e.g. aquatics, child-care) than others (e.g. gymnasium, group fitness activities). Key informants struggled to keep abreast of legislation changes and they relied on commercial, regulatory, and industry information sources rather than evidence of best practice. Reported factors influencing safety in MPRFs were classified into three types: internal (e.g. training, culture); external (e.g. weather, demographic change); and governance (e.g. insurance, industry standards). Comprehensive, relevant and accessible industry safety standards, which focus not only on OH&S but equally on health promotion principles and public health perspectives linked to injury prevention, are required. Training is needed to reflect these broader and equally important perspectives. Health/injury, fitness/recreation and insurance sector links should be improved to ensure a consistent, sustainable approach to safety. 相似文献
967.
Kadhim N. Salman Mary A. Stuart Jack Schmidt T. Borges Craig J. McClain Farrel R. Robinson Miao Li Larry W. Robertson 《Environmental science and pollution research international》2014,21(10):6400-6409
Copper (Cu) metabolism is altered in rats fed diets high in molybdenum (Mo) and low in Cu. This 10-week study was carried out to examine the effects of supplemental Mo (7.5–240 μg/g diet) on male Sprague–Dawley rats fed diets adequate in Cu (5 μg/g diet) and to determine the susceptibility of Mo-treated animals to the environmental pollutant 3,3′,4,4′-tetrabromobiphenyl (TBB). After 7 weeks of dietary treatment, half of the rats in each group received a single IP injection of TBB (150 μM/kg bw), while the other half received the corn oil vehicle. Rats sacrificed at 10 weeks showed no effects of Mo on growth, feed efficiency, or selected organ or tissue weights. Dose-dependent effects on plasma Mo (0–5.1 μg/mL), plasma Cu (0.95–0.20 μg/mL), and bone Cu (3.4–10 μg/g) in control through the high dose were found. Cu sequestration in the bone of Mo-treated rats is a new finding. TBB treatment resulted in dramatic weight loss and loss of absolute organ mass. Relative organ weights were increased, except for the thymus. TBB altered the concentrations of certain amino acids. Compared to control rats, this polybrominated biphenyl congener significantly decreased plasma Cu and ceruloplasmin at higher concentrations of dietary Mo and promoted the process of plasma Cu decrease by Mo, suggesting a combined effect. 相似文献
968.
Daniel Dancer Craig Baker-Austin James A. Lowther Rachel E. Hartnell David N. Lees L. O. Roberts 《Environmental Forensics》2014,15(3):256-264
A novel microbial source tracking (MST) method based on the detection of human and non-human markers was developed and applied to track the origin of fecal pollution in water systems. Mitochondrial DNA sequences were used to develop new quantitative real-time polymerase chain reaction (qPCR) assays for dog, poultry, and gull. The targets were included as part of a toolbox including human, cow, pig, and sheep assays. A primer and probe set for the detection of the human-specific nifH gene of Methanobrevibacter smithii was also designed as an indicator of human fecal contamination. The assays were tested for specificity and applied to fecal-spiked surface waters and environmental samples collected from two river catchments impacted by sources of human and non-human fecal contamination. The MST methods described were applicable to both spiked waters and environmental samples, and using the two approaches the origin of fecal pollution could be successfully determined in mixed source fecally polluted waters. 相似文献
969.
970.
Implications of differing input data sources and approaches upon forest carbon stock estimation 总被引:3,自引:0,他引:3
Michael A. Wulder Joanne C. White Graham Stinson Thomas Hilker Werner A. Kurz Nicholas C. Coops Ben?it St-Onge J. A. Trofymow 《Environmental monitoring and assessment》2010,166(1-4):543-561
Site index is an important forest inventory attribute that relates productivity and growth expectation of forests over time. In forest inventory programs, site index is used in conjunction with other forest inventory attributes (i.e., height, age) for the estimation of stand volume. In turn, stand volumes are used to estimate biomass (and biomass components) and enable conversion to carbon. In this research, we explore the implications and consequences of different estimates of site index on carbon stock characterization for a 2,500-ha Douglas-fir-dominated landscape located on Eastern Vancouver Island, British Columbia, Canada. We compared site index estimates from an existing forest inventory to estimates generated from a combination of forest inventory and light detection and ranging (LIDAR)-derived attributes and then examined the resultant differences in biomass estimates generated from a carbon budget model (Carbon Budget Model of the Canadian Forest Sector (CBM-CFS3)). Significant differences were found between the original and LIDAR-derived site indices for all species types and for the resulting 5-m site classes (p?<?0.001). The LIDAR-derived site class was greater than the original site class for 42% of stands; however, 77% of stands were within ±1 site class of the original class. Differences in biomass estimates between the model scenarios were significant for both total stand biomass and biomass per hectare (p?<?0.001); differences for Douglas-fir-dominated stands (representing 85% of all stands) were not significant (p?=?0.288). Overall, the relationship between the two biomass estimates was strong (R 2?=?0.92, p?<?0.001), suggesting that in certain circumstances, LIDAR may have a role to play in site index estimation and biomass mapping. 相似文献