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91.
Population declines in four species of eider; common (Somateria mollissima), king (Somateria spectabilis), spectacled (Somateria fischeri) and Steller's (Polysticta stelleri), have raised concerns about exposure to contaminants. Livers and kidney tissues were collected from eiders in Alaska and Russia for organic and elemental analyses. Results showed that organochlorine and many elemental levels were below toxic thresholds; however, in many cases, cadmium, copper, lead and serenium appeared high relative to other waterfowl and may warrant concern. With the exception of lead, local anthropogenic sources for these elements are not known. Although adverse physiological responses have not been documented in eiders, these four elements cannot be ruled out as contaminants of potential concern for some eider species.  相似文献   
92.
The Landscape Ecology of Invasive Spread   总被引:41,自引:1,他引:41  
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93.
Summary Female Mountain White-crowned Sparrows from Colorado were tested in a laboratory playback experiment to determine their response to male songs from their own natal dialect and to those from an alien dialect of the same subspecies, Zonotrichia leucophrys oriantha (Fig. 1). Observations were made on locomotor activity and copulation postures produced during each experimental test session.The subjects gave copulation displays almost exclusively when hearing their natal dialect and new or no displays when hearing the alien dialect (Fig. 2). The birds also exhibited significantly greater locomotor activity when hearing the natal dialect than they did when hearing the alien dialect (Fig. 3).We conclude that females are sensitized by their early song learning experience to be responsive to songs from their natal dialect and virtually sexually unresponsive to songs from an alien dialect. We speculate that the copulation posture given in the experiment implies that females in natural populations would preferably only mate assortatively with males from their natal dialect region.  相似文献   
94.
Quality assurance procedures to ensure consistency among chemistry laboratories typically involves the use of standard methods and state certification programs that require laboratories to demonstrate their ability to attain generic performance criteria. To assess whether these procedures are effective for ensuring comparability when processing local samples with potentially complex matrices, seven experienced, state-certified laboratories participated in an intercalibration exercise. Each laboratory was permitted to use their typical methodology for quantifying PAH, PCB and DDT on shared samples collected from Santa Monica Bay and the Palos Verdes Shelf, two sites with a complex mix of constituents. In the initial intercalibration exercise, results from these laboratories differed by as much as an order of magnitude for all three chemical groups. Much, but not all, of the difference was attributable to differences in detection capability. A series of studies was conducted to identify the reasons for the observed differences, which varied among laboratories and included methodological differences, instrument sensitivity differences, and differing interpretations of chromatograms. Following these investigations and resulting modifications to laboratory procedures, the exercise was repeated. The average coefficient of variation among laboratories across all chemical parameters was reduced to less than 30%. Our results suggest that performance-based chemistry can produce comparable results, but the certification processes presently in place that focus on general laboratory procedures and simple matrices are insufficient to achieve comparability.  相似文献   
95.
The development and regulatory acceptance of monitored natural attenuation (MNA) as a remedial strategy has forever changed the field of environmental cleanup. MNA is continuing to develop but it is challenged by a lack of a clear definition for the appropriate application of the MNA strategy. This challenge has resulted in the lack of a significant record of restoration and site closure. Environmental professionals face challenges in providing guidance that addresses how to manage these sites when technologies, performance monitoring, and even environmental conditions are subject to further development, refinement, and/or altered perspectives. As our experience and institutional knowledge grows around the implementation of MNA, we have the opportunity to develop “second‐generation” management tools and procedures for optimizing sites utilizing MNA as a part of a comprehensive site management plan. This opportunity is the focus of the Enhanced Attenuation: Chlorinated Organics (EACO) Team of the Interstate Technology Regulatory Council (ITRC). The development of the “second‐generation” tools/procedures has included defining EA and evaluating, through the use of a national survey of state regulators, the experience with MNA and interest in EA. The results of these two efforts formed the basis for developing a framework that provides a “bridge” from active treatment to MNA. © 2007 Wiley Periodicals, Inc.  相似文献   
96.
Environmental psychology is a field of such great diversity—in topics of interest, research approaches, in disciplinarity—that it often appears to lack coherence, exemplified by its poor fit within paradigmatic frameworks found in academic psychology, resulting in its “outlier” status. This paper explores the work of the environmental gerontologist M. Powell Lawton, as an exemplar of environmental psychology research, suggesting that such a review renders greater insight into the current state of the field than any top-down applied conceptual framework. Themes discussed include Lawton's theoretical perspective on the person, the environment, and the relationship between them, his inquiry at various units of analysis; the type of knowledge valued as evidenced in his work; and his fundamental applied orientation, all of which are reflective of contemporary directions within environmental psychology as a whole. Reviewed is Lawton's final proposal that takes an “epistemologically inclusive” approach, embodying all of the themes above and reflective of inquiry sought within pragmatic psychology. As such, it is argued that environmental psychology may find great affinity with the pragmatic psychology approach currently gaining impetus within applied and clinical psychology.  相似文献   
97.
Identification of oyster species is still largely based on phenotypic characters that are highly plastic. Prompted by the proposed introduction of the Asian oyster species Crassostrea ariakensis into the Chesapeake Bay region of the U.S.A., this study uses molecular genetic information to understand the taxonomic framework surrounding C. ariakensis and to confidently distinguish among various sympatric oyster species. Putative samples of C. ariakensis and other species of cupped oysters from across Asia were collected and phylogenetic analyses were conducted on DNA sequences of both nuclear (ITS-1) and mitochondrial (COI) regions. Trees generated based on the two independent molecular datasets were highly congruent, and indicate that many oysters collected for this study as C. ariakensis were originally misidentified. Results also indicate that C. ariakensis, C. hongkongensis and C. nippona are distinct, but closely related species. There is strong support in both analyses for a close relationship between C. gigas and C. sikamea, as well as between C. belcheri and C. gryphoides, and between C. iredalei and C. madrasensis. The parsimony analyses based on these DNA markers, however, did not provide evidence to support C. angulata as a distinct species from C. gigas. Overall, the results emphasize the need for rigorous species identification, and additional extensive and intensive sampling to more accurately determine relationships among Crassostrea species, define their geographic distributions, and establish existing sympatry patterns.  相似文献   
98.
Los Angeles has a long history of importing water; however, drought, climate change, and environmental mitigation have forced the City to focus on developing more local water sources (target of 50% local supply by 2035). This study aims to improve understanding of water cycling in Los Angeles, including the impacts of imported water and water conservation policies. We evaluate the influence of local water restrictions on discharge records for 12 years in the Ballona Creek (urban) and Topanga Creek (natural) watersheds. Results show imported water has significantly altered the timing and volume of streamflow in the urban Ballona watershed, resulting in runoff ratios above one (more streamflow than precipitation). Further analysis comparing pre‐ vs. during‐mandatory water conservation periods shows there is a significant decrease in dry season streamflow during‐conservation in Ballona, indicating that prior to conservation efforts, heavy irrigation and other outdoor water use practices were contributing to streamflow. The difference between summer streamflow pre‐ vs. during‐conservation is enough to serve 160,000 customers in Los Angeles. If Los Angeles returns to more watering days, educating the public on proper irrigation rates is critical for ensuring efficient irrigation and conserving water; however, if water restrictions remain in place, the City must take the new flow volumes into account for complying with water quality standards in the region.  相似文献   
99.
This work investigates the oxidative aging of preformed secondary organic aerosol (SOA) derived from α-pinene ozonolysis (~100 ppbv hydrocarbon [HCx] with excess of O3) within the University of California–Riverside Center for Environmental Research and Technology environmental chamber that occurs after introduction of additional hydroxyl (OH) and nitrate (NO3) radicals. Simultaneous measurements of SOA volume concentration, hygroscopicity, particle density, and elemental chemical composition (C:O:H) reveal increased particle wall-loss-corrected SOA formation (1.5%, 7.5%, and 15.1%), increase in oxygen-to-carbon ratio (O/C; 15.6%, 8.7%, and 8.7%), and hydrophilicity (4.2%, 7.4%, and 1.4%) after addition of NO (ultraviolet [UV] on), H2O2 (UV on), and N2O5 (dark), respectively. The processing observed as an increase in O/C and hydrophilicity is attributed to OH and NO3 reactions with first-generation vapor products and UV photolysis. The rate of increase in O/C appears to be only sufficient to achieve semivolatile oxygenated organic aerosol (SV-OOA) on a day time scale even at the raised chamber radical concentrations. The additional processing with UV irradiation without addition of NO, H2O2, or N2O5 is observed, adding 5.5% wall-loss-corrected volume. The photolysis-only processing is attributed to additional OH generated from photolysis of the nitrous acid (HONO) offgasing from chamber walls. This finding indicates that OH and NO3 radicals can further alter the chemical composition of SOA from α-pinene ozonolysis, which is proved to consist of first-generation products.

Implications: Secondary organic aerosol (SOA) may undergo aging processes once formed in the atmosphere, thereby altering the physicochemical and toxic properties of aerosol. This study discusses SOA aging of a major biogenic volatile organic compound (VOC; α-pinene) after it initially forms SOA. Aging of the α-pinene ozonolysis system by OH (through NO or H2O2 injection), NO3 (through N2O5 injection), and photolysis is observed. Although the reaction rate appears to be only sufficient to achieve semivolatile oxygenated organic aerosol (SV-OOA) level of oxygenation on a 1-day scale, it is important that SOA aging be considered in ambient air quality models. Aging in this study is attributed to further oxidation of gas-phase oxidation products of α-pinene ozonolysis.

Supplemental Materials: Supplemental materials are available for this paper. Go to the publisher's online edition of the Journal of the Air &; Waste Management Association for information on the referenced α-pinene ozonolysis reaction and chamber reactor temperature.  相似文献   
100.
The investigators developed a system to measure black carbon (BC) and particle-bound polycyclic aromatic hydrocarbon (PAH) emission factors during roadside sampling in four cities along the United States–Mexico border, Calexico/Mexicali and El Paso/Juárez. The measurement system included a photoacoustic analyzer for BC, a photoelectric aerosol sensor for particle-bound PAHs, and a carbon dioxide (CO2) analyzer. When a vehicle with measurable emissions passed the system probe, corresponding BC, PAH, and CO2 peaks were evident, and a fuel-based emission factor was estimated. A picture of each vehicle was also recorded with a digital camera. The advantage of this system, compared with other roadside methods, is the direct measurement of particulate matter components and limited interference from roadside dust. The study revealed some interesting trends: Mexican buses and all medium-duty trucks were more frequently identified as high emitters of BC and PAH than heavy-duty trucks or passenger vehicles. In addition, because of the high daily mileage of buses, they are good candidates for additional study. Mexican trucks and buses had higher average emission factors compared with U.S. trucks and buses, but the differences were not statistically significant. Few passenger vehicles had measurable BC and PAH emissions, although the highest emission factor came from an older model passenger vehicle licensed in Baja California.  相似文献   
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