排序方式: 共有29条查询结果,搜索用时 0 毫秒
1.
Libby, Montana is the only PM2.5 nonattainment area in the western United States with the exceptions of parts of southern California. During January through
March 2005, a particulate matter (PM) sampling program was conducted within Libby’s elementary and middle schools to establish
baseline indoor PM concentrations before a wood stove change-out program is implemented over the next several years. As part
of this program, indoor concentrations of PM mass, organic carbon (OC), and elemental carbon (EC) in five different size fractions
(>2.5, 1.0–2.5, 0.5–1.0, 0.25–0.5, and <0.25 μm) were measured. Total measured PM mass concentrations were much higher inside
the elementary school, with particle size fraction (>2.5, 0.5–1.0, 0.25–0.5, and <0.25 μm) concentrations between 2 and 5
times higher when compared to the middle school. The 1.0–2.5 μm fraction had the largest difference between the two sites,
with elementary school concentrations nearly 10 times higher than the middle school values. The carbon component for the schools’
indoor PM was found to be predominantly composed of OC. Measured total OC and EC concentrations, as well as concentrations
within individual size fractions, were an average of two to five times higher at the elementary school when compared to the
middle school. For the ultrafine fraction (<0.25), EC concentrations were similar between each of the schools. Despite the
differences in concentrations between the schools at the various fraction levels, the OC/EC ratio was determined to be similar. 相似文献
2.
Historical streamflow and concentration data were used in regression models to estimate the annual flux of nitrogen (N) to the Gulf of Mexico and to determine where the nitrogen originates within the Mississippi Basin. Results show that for 1980-1996 the mean annual total N flux to the Gulf of Mexico was 1,568,000 t yr-1. The flux was about 61% nitrate N, 37% organic N, and 2% ammonium N. The flux of nitrate N to the Gulf has approximately tripled in the last 30 years with most of the increase occurring between 1970 and 1983. The mean annual N flux has changed little since the early 1980s, but large year-to-year variations in N flux occur because of variations in precipitation. During wet years the N flux can increase by 50% or more due to flushing of nitrate N that has accumulated in the soils and unsaturated zones in the basin. The principal source areas of N are basins in southern Minnesota, Iowa, Illinois, Indiana, and Ohio that drain agricultural land. Basins in this region yield 1500 to more than 3100 kg N km-2 yr-1 to streams, several times the N yield of basins outside this region. 相似文献
3.
Dirk Erpenbeck John N. A. Hooper Isabelle Bonnard Patricia Sutcliffe Mayuri Chandra Pierre Perio Carsten Wolff Bernard Banaigs Gert W?rheide Cécile Debitus Sylvain Petek 《Marine Biology》2012,159(5):1119-1127
Sponges of the family Dysideidae (Dictyoceratida) are renowned for their diversity of secondary metabolites, and its genus Lamellodysidea, particularly Lamellodysidea herbacea, is the most studied taxon biochemically. Despite its importance, the taxonomic status of L. herbacea—whether it is a distinct species or a species complex—has never been assessed. Recent biochemical profiling revealed anti-plasmodial activity of brominated compounds in Lamellodysidea of the Pacific. Here, we present a comparative chemotaxonomic and molecular analysis of selected Dysideidae from the Pacific and the Indian Ocean (New Caledonia, Great Barrier Reef, Fiji, Mayotte, Guam, Palau). We investigated the phylogenetic relationships between the populations and assessed their bioactive (PBDE) compounds in order to unravel the taxonomic status of this commercially important group of sponges and assessed patterns of dispersal and biochemical variation. The molecular phylogeny was based on the internal transcribed ribosomal spacer and compared against a PBDE phylogeny for several specimens. Molecular data revealed a diversity of Indo-Pacific L. herbacea populations, also reflected by different PBDE compound profiles. Molecular and biochemical data also revealed a Lamellodysidea species new to science. Several specimens misidentified as Lamellodysidea were detected based on their position on different clades in the molecular phylogeny and their production of different halogenated compounds (brominated vs. chlorinated). The direct comparison of molecular and biochemical data also provided evidence for the occurrence of a host switch event and support for the theory that abiotic factors, such as sedimentation, affect the chemical constituents produced in L. herbacea. 相似文献
4.
Sean M. Richards Todd A. Anderson Michael J. Hooper Scott T. McMurry Steven B. Wall Hiroshi Awata 《毒物与环境化学》2013,95(3-4):215-234
European starling (Sturnus vulgaris) nestlings were used as a surrogate to study the effect of chlorpyrifos application to a corn agroecosystem on songbird reproduction. Chlorpyrifos was applied in a T‐band at 1.3 kg AI/ha, and residues were measured in soil, earthworms, ground‐dwelling insects, and diet items collected from the crop of starling nestlings. Chlorpyrifos levels in soil peaked at 34.2 μg/g, 4 days post‐application, and dissipated to trace levels by 64 days post‐application. Concentrations of chlorpyrifos in earthworms and ground‐dwelling insects reached 0.9 and 0.7 ug/g, respectively. Starling nestling diet items included invertebrates from eight orders with chlorpyrifos concentrations ranging from trace levels to 10.6 μg/g in earthworms. Nestling brain and plasma cholinesterase (ChE) activity and body mass measurements were taken at 3, 8, and 13 days post‐hatch (DPH). Adult starling fecundity was also measured. Body mass differences between treatment and reference site nestlings at 3 and 13 DPH were not significant at α = 0.05. However, 8 DPH nestlings from the Treatment Site had a transient reduction in weight (p = 0.03) when compared with 8 DPH reference nestlings. There were no significant differences in brain or plasma ChE activities of 3, 8, or 13 DPH nestlings. Further, multiple measures of fecundity (i.e., clutch size, hatching percentage, and fledging percentage) indicated that chlorpyrifos application did not affect starling nestling survival to fledging, as the values from the Treatment and Reference Site were nearly identical. This screening‐level study suggests that although one age group of starling nestlings from the Treatment Site weighed less than their Reference Site counterparts, a single T‐band application of chlorpyrifos did not impair starling nesting success. 相似文献
5.
GABRIELLA SUSZTER ÁRPÁD AMBRUS MARIANNA SCHWEIKERT TURCU PHILIPP MARTIN KLAUS 《Journal of environmental science and health. Part. B》2013,48(5):531-552
The efficiency of four sample processing methods was tested with eight different types of soils representing the major proportion of cultivated soils. The principle of sampling constant was applied for characterizing the efficiency of the procedures and testing the well-mixed status of the prepared soil. The test material was 14C-labeled atrazine that enabled keeping the random error of analyses ≤ about 1%. Adding water to the soil proved to be the most efficient and generally applicable procedure resulting in about 6% relative sample processing uncertainty for 20 g test portions. The expected error is inversely proportional to the mass of test portion. Smashing and manual mixing of soil resulted in about four times higher uncertainty than mixing with water. Grinding of soil is applicable for dry soils only, but the test procedure applied was not suitable for estimating a typical uncertainty of processing dry soil samples. Adding dry ice did not improve the efficiency of sample processing. 相似文献
6.
The environmental burden of collecting recoverables from households is generally omitted from life-cycle analyses comparing the environmental outcome of using secondary material from post-consumer waste (PCW) with virgin feedstock. However, this burden can be considerable, depending upon the characteristics of the collection methods employed. Given that the basic objective of recycling is to secure environmental benefits, it is vital that the burden of collection through both bring/dropoff and kerbside schemes is taken into account if a valid assessment of the environmental balance resulting from PCW recycling is to be made. This paper presents survey data comparing the burden of collection for different types of recycling provision. It describes the site and spatial characteristics determining the amount of transport dedicated to collection at bring/drop-off sites. Predictor variables are identified as measures of these characteristics, and the survey data compared with them. A regression model to assess energy use at bring/drop-off sites with varying characteristics is then developed. The potential uses of the techniques presented include the evaluation of the environmental burdens of recycling provision at the waste collection authority and regional level, allowing more informed choices to be made in the development of recycling provision from an environmental standpoint. 相似文献
7.
Charles A. Ambrose Richard Hooper Anthony K. Potter M. Margaret Singh 《Resources, Conservation and Recycling》2002,36(4)
Mechanical recycling of 100% post-consumer plastic waste into high-quality products has been performed. The chemical and physical properties of these recycled materials have been compared with similar products manufactured from virgin resins. The properties of a blow-moulded bottle prepared from 100% post-consumer high-density polyethylene (HDPE) showed that this recycled polymer exceeded the materials specifications for virgin plastic designs. Similarly, a sample of thermoplastic polyolefin (TPO, 100% polypropylene), obtained entirely from shredder residue (SR) displayed sufficient material strength for future separation and reprocessing. 相似文献
8.
Fipronil is a phenyl pyrazole insecticide registered for agricultural use in many countries. Avian exposure to fipronil occurs mainly by ingesting contaminated insects or seeds. There is little information regarding the toxicological effects of fipronil in avian species and even less research documenting avian behavioural responses to fipronil ingestion. We examined the effects of a single oral dose of fipronil in northern bobwhite quail, the most fipronil-sensitive species tested to date, in respect to signs of intoxication and the metabolic fate of fipronil. Fipronil-treated birds did not eat or drink following pesticide administration, and as a result lost a significant amount of body mass. Treated birds also appeared withdrawn and did not respond to disturbance within the first hour after treatment. Identifiable signs of fipronil toxicity were not observed until at least 2d after treatment. Chemical analyses indicated a difference between fipronil and fipronil-sulfone residue distribution and bioaccumulation, with significantly higher (30- to 1000-fold) tissue concentrations of the sulfone detected at all time points from 8 to 96 h post-dose in brain, liver and adipose tissues. Tissue sulfone concentrations increased significantly in fipronil-treated birds, peaking at 72 h post-dose. Body mass decreased at all time points in dosed birds. The coincidence of the particular intoxication symptoms with the time course of rise in brain sulfone levels after fipronil dosing gives insight into possible mechanisms of toxicity in this highly sensitive species. 相似文献
9.
Pajaree Thongsanit Beverley Hooper Martin Hooper Wongpun Limpaseni 《Journal of the Air & Waste Management Association (1995)》2013,63(12):1490-1498
Abstract Air samples of particulate matter (PM) with an aerodynamic diameter less than 10 µm (PM10) were collected from six sites in Bangkok, Thailand, using high-volume air samplers. Daily samples were taken at intervals of 12 days from November 1999 to November 2000. Size-selected sampling using a multislit Andersen size-fractionated cascade impactor was undertaken at one site in central Bangkok to identify particulate size distribution. The annual average PM10 concentration at all six sites exceeded the Thailand National Ambient Air Quality Standard (NAAQS) of 50 µg/m3. The daily PM10 concentrations at heavy traffic roadside areas ranged between 30 and 160 µg/m3. The highest PM10 level occurred during the winter period (November–February), which is the dry season. From our results, which are based on a 1-yr survey, it can be observed that the particulate concentrations are associated with traffic volumes and seasonal factors (temperature and rainfall). The relative importance of size fractions in contributing to PM load is presented and discussed. Twenty polycyclic aromatic hydro-carbons (PAHs) associated with PM have been identified and quantified. The summed PAHs based on the 20 species had an average concentration of 60 ng/m3. Benzo(e)pyrene, indeno(123cd)pyrene, and benzo(ghi)perylene were the major compounds with average concentrations of 8, 10, and 13 ng/m3, respectively. Results indicate that more than 97% of PAHs were found in the small particulate size range of <0.95 µm. 相似文献
10.
Differential use of stored sperm during oviposition in the damselfly Calopteryx splendens xanthostoma (Charpentier) 总被引:2,自引:0,他引:2
Female Calopteryx splendens xanthostoma (Charpentier) (Odonata), have two discrete sperm storage organs, the bursa copulatrix and the paired spermathecae. We used
the Random Amplified Polymorphic DNA(RAPD) profiling technique to determine from which sperm storage organ spermatozoa were used to fertilise eggs during behaviourally
distinct oviposition bouts. During oviposition bouts following remating sperm from the bursa copulatrix are largely used to
fertilise eggs, but when females avoid remating before an oviposition bout the sperm used to fertilise eggs are derived mainly
from the paired spermathecae. Our observations suggest that female C. s. xanthostoma can avoid male paternity assurance mechanisms by a combination of behavioural and anatomical adaptation: the reason(s) they
do so is unclear.
Received: 28 November 1995/Accepted after revision: 5 August 1996 相似文献