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241.
Peters TM Riss AL Holm RL Singh M Vanderpool RW 《Journal of environmental monitoring : JEM》2008,10(4):541-551
Real-time particle sizers provide rapid information about atmospheric particles, particularly peak exposures, which may be important in the development of adverse health outcomes. However, these instruments are subject to erroneous readings in high-humidity environments when compared with measurements from filter-based, federal reference method (FRM) samplers. Laboratory tests were conducted to evaluate the ability of three inlet conditioners to dry aerosol prior to entering a real-time particle sizer for measuring coarse aerosols (Model 3321 Aerodynamic Particle Sizer, APS) under simulated highly humid conditions. Two 30 day field studies in Birmingham, AL, USA were conducted to compare the response of two APSs operated with and without an inlet conditioner to that measured with FRM samplers. In field studies, the correlation of PM(10-2.5) derived from the APS and that measured with the FRM was substantially stronger with an inlet conditioner applied (r2 ranged from 0.91 to 0.99) than with no conditioner (r2 = 0.61). Laboratory experiments confirmed the ability of the heater and desiccant conditioner to remove particle-borne moisture. In field tests, water was found associated with particles across the sizing range of the APS (0.5 microm to 20 microm) when relative humidity was high in Birmingham. Certain types of inlet conditioners may substantially improve the correlation between particulate mass concentration derived from real-time particle sizers and filter-based samplers in humid conditions. 相似文献
242.
Hillslope runoff and leaching studies, catchment-scale water quality measurements and P retention and release characteristics of stream bank and catchment soils were used to better understand reasons behind the reported ineffectiveness of riparian buffers for phosphorus (P) management in catchments with sandy soils from south-west Western Australia (WA). Catchment-scale water quality measurements of 60 % particulate P (PP) suggest that riparian buffers should improve water quality; however, runoff and leaching studies show 20 times more water and 2 to 3 orders of magnitude more P are transported through leaching than runoff processes. The ratio of filterable reactive P (FRP) to total P (TP) in surface runoff from the plots was 60 %, and when combined with leachate, 96 to 99 % of P lost from hillslopes was FRP, in contrast with 40 % measured as FRP at the large catchment scale. Measurements of the P retention and release characteristics of catchment soils (<2 mm) compared with stream bank soil (<2 mm) and the <75-μm fraction of stream bank soils suggest that catchment soils contain more P, are more P saturated and are significantly more likely to deliver FRP and TP in excess of water quality targets than stream bank soils. Stream bank soils are much more likely to retain P than contribute P to streams, and the in-stream mixing of FRP from the landscape with particulates from stream banks or stream beds is a potential mechanism to explain the change in P form from hillslopes (96 to 99 % FRP) to large catchments (40 % FRP). When considered in the context of previous work reporting that riparian buffers were ineffective for P management in this environment, these studies reinforce the notion that (1) riparian buffers are unlikely to provide fit-for-purpose P management in catchments with sandy soils, (2) most P delivered to streams in sandy soil catchments is FRP and travels via subsurface and leaching pathways and (3) large catchment-scale water quality measurements are not good indicators of hillslope P mobilisation and transport processes. 相似文献
243.
Deborah J. Ballantine Robert J. Davies-Colley 《Environmental monitoring and assessment》2014,186(3):1939-1950
Recent assessments of water quality in New Zealand have indicated declining trends, particularly in the 40 % of the country’s area under pasture. The most comprehensive long-term and consistent water quality dataset is the National Rivers Water Quality Network (NRWQN). Since 1989, monthly samples have been collected at 77 NRWQN sites on 35 major river systems that, together, drain about 50 % of New Zealand’s land area. Trend analysis of the NRWQN data shows increasing nutrient concentrations, particularly nitrogen (total nitrogen and nitrate), over 21 years (1989–2009). Total nitrogen and nitrate concentrations were increasing significantly over the first 11 years (1989–2000), but for the more recent 10-year period, only nitrate concentrations continued to increase sharply. Also, the increasing phosphorus trends over the first 11 years (1989–2000) levelled off over the later 10-year period (2000–2009). Conductivity has also increased over the 21 years (1989–2009). Visual clarity has increased over the full time period which may be the positive result of soil conservation measures and riparian fencing. NRWQN data shows that concentrations of nutrients increase, and visual clarity decreases (i.e. water quality declines), with increasing proportions of pastoral land in catchments. As such, the increasing nutrient trends may reflect increasing intensification of pastoral agriculture. 相似文献
244.
William S. Fisher Leska S. Fore Leah M. Oliver Charles Lobue Robert Quarles Jed Campbell Peggy Harris Becky Hemmer Sherry Vickery Mel Parsons Aaron Hutchins Kent Bernier Danny Rodriguez Patricia Bradley 《Environmental monitoring and assessment》2014,186(11):7165-7181
States may protect coral reefs using biological water quality standards outlined by the Clean Water Act. This requires biological assessments with indicators sensitive to human disturbance and regional, probability-based survey designs. Stony coral condition was characterized on a regional scale for the first time in the nearshore waters of the US Virgin Islands (USVI). Coral composition, abundance, size, and health were assessed at 66 stations in the St. Croix region in fall 2007 and at 63 stations in the St. Thomas and St. John region in winter 2009. Indicators were chosen for their sensitivity to human disturbance. Both surveys were probability-based (random) designs with station locations preselected from areas covered by hardbottom and coral reef substrate. Taxa richness was as high as 21 species but more than half the area of both regions exhibited taxa richness of <10 species in the 25 m2 transect area. Coral density was as high as 5 colonies m?2 but more than half the area of both regions had <2 colonies m?2. Both regions showed similar dominant species based on frequency of occurrence and relative abundance. Because of large colony sizes, Montastrea annularis provided more total surface area and live surface area than more abundant species. The surveys establish baseline regional conditions and provide a foundation for long-term regional monitoring envisioned by the USVI Department of Planning and Natural Resources. The probabilistic sampling design assures the data can be used in Clean Water Act reporting. 相似文献
245.
Robert Liu R.S. Shieh Ruth Y.L. Yeh C.H. Lin 《Waste management (New York, N.Y.)》2009,29(11):2842-2845
The traditional burning process is used to recover copper from scrapped PC board (printed circuit board) but it causes serious environmental problems. In this research a new process was developed which not only prevents pollution problems, but also maximizes the utility of all the materials on the waste board. First, the scrapped PC board was crushed and grounded, then placed in the NH3/NH5CO3 solution with aeration in order to dissolve copper. After distilling the copper NH3/NH5CO3 solution and then heating the distilled residue of copper carbonate, pure copper oxide was obtained with particle size of about 0.2 μm and the shape elliptical. The remaining solid residue after copper removal was then leached with 6 N hydrochloric acid to remove tin and lead. The last residue was used as a filler in PVC plastics. The PVC plastics with PC board powder as filling material was found to have the same tensile strength as unfilled plastics, but had higher elastic modulus, higher abrasion resistance, and was cheaper. 相似文献
246.
247.
248.
Russell M. Wise Graham P. von Maltitz Robert J. Scholes Chris Elphinstone Renee Koen 《Mitigation and Adaptation Strategies for Global Change》2009,14(7):579-604
Minimising the cost of repeatedly estimating C (C) stocks is crucial to the financial viability of projects that seek to sell
C credits. Depending on the price of C, this may imply less or more sampling effort than would be applied for science objectives.
In systems with heterogeneous C pools, such as savannas, this translates into a variable-effort sampling strategy that maximises
the marginal additional C that can be claimed per incremental unit of effort expended. Analysis of a savanna in north-eastern
South Africa indicates relatively modest returns per hectare due to the small C quantities and low sequestration rates. Under
these conditions, areas in excess of 1,000 ha and infrequent sampling frequencies of 5–10 years are required to make such
projects financially viable. For such projects the sample variance, number of samples, cost per sample and establishment costs
have negligible impacts on financial viability. It was also found that the soil-C pool contributes up to three times the net
returns of the aboveground C pool and provides a strong argument to monitor soil C for certification and market trading. The
financial viability estimates, however, do not include the management or opportunity costs incurred in changing the land use.
The economies of scale identified in this study combined with the massive area covered by savannas indicate that these additional
costs can be covered. Further research is recommended to quantify these costs and interrogate the feasibility of large scale
(in excess of 10,000 ha) C-sink projects in savanna systems. 相似文献
249.
Robert A. Leidy 《Conservation biology》2009,23(4):1060-1061
250.
The Triad approach was developed primarily to limit decision uncertainty during cleanups at hazardous waste sites. The fundamental principles of the Triad approach include development of a site characterization model and use of emerging technologies, which can provide data at a higher density than could be affordably collected using traditional data collection methodologies, to refine the model in essentially real time. New data formats are used collaboratively with data in traditional formats to iteratively pin down the relative concentration, nature, and extent of contaminants, thus minimizing decision uncertainties. This article examines the potential admissibility as evidence in legal proceedings of data collected by technologies designed to improve the density of information that are commonly used during the course of Triad‐type projects. The article explains that such criteria may vary depending on the purpose for which the evidence is to be used (e.g., as direct evidence to prove site conditions or as support for the testimony of an expert witness) and the court in which the legal proceeding would take place (e.g., federal court or state court). Admissibility in federal courts of data both as direct evidence and as support for expert witness testimony is covered. © 2005 Wiley Periodicals, Inc. 相似文献