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61.
Some of the most important demographic parameters underlying the resilience of coral communities are determined by their patterns
of reproduction. In this study, a variety of methods were used to investigate the patterns of spawning, larval development
and dispersal for scleractinian corals at an isolated reef system off northwestern Australia. Two distinct periods of gamete
maturation and multi-specific spawning occurred each year, during Spring and Autumn, in contrast to the single season of mass
spawning described on most other reefs around Australia. The subsequent rates of embryogenesis and larval development were
among the fastest described for corals, with pre-competency periods of approximately 3 days. Within 3 days of spawning, slicks
of spawn and current drifters had dispersed up to 5 km, and up to 10 km after 6 days, while the times taken for drifters to
travel between adjacent (>240 km) reef systems were similar to or greater than the upper competency periods of most coral
larvae. Thus, under these conditions, the entire reef system, and to some extent the reefs within the system, may largely
be self-seeded; rates of immigration from other systems are probably insufficient to rapidly increase the recovery of communities
within years of a major disturbance. These results have implications for the management of isolated reef systems, highlighting
the need to minimize local stressors and maximize community resilience to the increasing scale of disturbance and habitat
fragmentation. 相似文献
62.
Li Z Sjödin A Romanoff LC Horton K Fitzgerald CL Eppler A Aguilar-Villalobos M Naeher LP 《Environment international》2011,37(7):1157-1163
Burning biomass fuels such as wood on indoor open-pit stoves is common in developing regions. In such settings, exposure to harmful combustion products such as fine particulate matter (PM(2.5)), carbon monoxide (CO) and polycyclic aromatic hydrocarbons (PAHs) is of concern. We aimed to investigate if the replacement of open pit stoves by improved stoves equipped with a chimney would significantly reduce exposure to PAHs, PM(2.5) and CO. Two stove projects were evaluated in Peru. Program A was part of the Juntos National Program in which households built their own stoves using materials provided. In Program B, Barrick Gold Corporation hired a company to produce and install the stoves locally. A total of 30 and 27 homes participated in Program A and B, respectively. We collected personal and kitchen air samples, as well as morning urine samples from women tasked with cooking in the households before and after the installation of the improved stoves. Median levels of PM(2.5) and CO were significantly reduced in kitchen and personal air samples by 47-74% after the installation of the new stoves, while the median reduction of 10 urinary hydroxylate PAH metabolites (OH-PAHs) was 19%-52%. The observed OH-PAH concentration in this study was comparable or higher than the 95th percentile of the general U.S. population, even after the stove intervention, indicating a high overall exposure in this population. 相似文献
63.
J. Luke Boutwell John V. Westra 《Journal of the American Water Resources Association》2016,52(6):1472-1481
Coastal communities along the United States coast often experience significant economic damage resulting from the impacts of tropical storms and hurricanes. Research suggests that certain factors that affect economic damages are increasing the vulnerability of coastal communities. Population growth, which increases vulnerability by placing valuable lives and assets in the path of storms, is expected to increase. Climate change has the potential to cause more frequent and intense storms, and coastal wetland loss is contributing to the vulnerability of coastal populations. Wetlands conservation and restoration is often advocated for as a means of reducing the impacts of coastal storms. The relationship between wetlands and storm surge energy is understood relatively well in physical terms, but very little economic analysis has been conducted to estimate the degree to which wetlands reduce economic impacts. Using factor analysis, the relationships among coastal populations, wetlands, storm intensity, and economic damage are explored. The factor analysis suggests that wetland presence is associated with a reduction in economic damages from coastal storms. Factor score analysis suggests that the proportion of damage explained by wetland presence is smaller for more intense storms. These results are consistent with those found in the physical science literature and have potentially large consequences for how wetlands are used in risk reduction. 相似文献
64.
Luke Fowler 《环境政策》2016,25(2):315-337
State-level public opinion on the environment within the US is examined, using data from the General Social Survey (GSS) from 2000 to 2010. A Multilevel Regression and Post-Stratification (MRP) approach is taken to estimate three different survey items on environmental issues at the US state level. This allows for a comparable understanding of state-level public opinion on environmental issues, which is then connected to economic, environmental, and political conditions, and representation in policy making. The findings indicate the MRP technique is a sophisticated way to make accurate estimations of state-level public opinion, and those estimates provide further insight into the shaping of public opinion and public policy. 相似文献
65.
Plastic production pellets collected from beaches of south west England contain variable concentrations of trace metals (Cr, Co, Ni, Cu, Zn, Cd and Pb) that, in some cases, exceed concentrations reported for local estuarine sediments. The rates and mechanisms by which metals associate with virgin and beached polyethylene pellets were studied by adding a cocktail of 5 μg L(-1) of trace metals to 10 g L(-1) pellet suspensions in filtered seawater. Kinetic profiles were modelled using a pseudo-first-order equation and yielded response times of less than about 100 h and equilibrium partition coefficients of up to about 225 ml g(-1) that were consistently higher for beached pellets than virgin pellets. Adsorption isotherms conformed to both the Langmuir and Freundlich equations and adsorption capacities were greater for beached pellets than for virgin pellets. Results suggest that plastics may represent an important vehicle for the transport of metals in the marine environment. 相似文献
66.
Herbert Musarurwa Luke Chimuka 《Journal of environmental science and health. Part. B》2013,48(9):770-780
The ever-increasing demand for determining pesticides at low concentration levels in different food matrices requires a preliminary step of pre-concentration which is considered a crucial stage. Recently, the parameter of “greenness” during sample pre-concentration of pesticides in food matrices is as important as selectivity in order to avoid using harmful organic solvents during sample preparation. Developing new green pre-concentration techniques is one of the key subjects. Thus, to reduce the impact on the environment during trace analysis of pesticides in food matrices, new developments in pre-concentration have gone in three separate directions: the search for more environmentally friendly solvents, miniaturization and development of solvent-free pre-concentration techniques. Eco-friendly solvents such as supercritical fluids, ionic liquids and natural deep eutectic solvents have been developed for use as extraction solvents during pre-concentration of pesticides in food matrices. Also, miniaturized pre-concentration techniques such as QuEChERS, dispersive liquid–liquid micro-extraction and hollow-fiber liquid-phase micro-extraction have been used during trace analysis of pesticides in food samples as well as solvent-free techniques such as solid-phase micro-extraction and stir bar sorptive extraction. All these developments which are aimed at ensuring that pesticide pre-concentration in different food matrices is green are critically reviewed in this paper. 相似文献
67.
Andrea Jessen Andrew Randall Debra Reinhart Luke Daly 《Water environment research》2008,80(6):561-569
This study examined whether ferrate could meet the international standards for successful ballast water treatment, including final concentrations of less than 1 CFU/mL of Enterococci, less than 2.5 CFU/mL of Escherichia coli, and less than 1 CFU/100 mL of Vibrio cholerae. Pure cultures of E. coli, Klebsiella pneumoniae, and V. cholerae, and a mixed culture of Enterococcus faecium and E. faecilis were grown in saline solution to simulate ballast water and were treated with dosages of ferrate ranging from 0.25 to 5.0 mg/L. A ferrate dose of 5 mg/L resulted in complete disinfection of all organisms tested, and smaller dosages were also very effective. Tailing was consistently observed, and the Hom's model (1972) appeared to most accurately represent the action of ferrate on these organisms. Salinity and pH did not adversely affect results, and regrowth was not a problem. Ferrate shows good potential as an effective disinfectant in the treatment of ballast water. 相似文献
68.
69.
James Flynn Barry Lefer Bernhard Rappenglück Michael Leuchner Ryan Perna Jack Dibb Luke Ziemba Casey Anderson Jochen Stutz William Brune Xinrong Ren Jingqiu Mao Winston Luke Jennifer Olson Gao Chen James Crawford 《Atmospheric environment (Oxford, England : 1994)》2010,44(33):4126-4133
A radiative transfer model and photochemical box model are used to examine the effects of clouds and aerosols on actinic flux and photolysis rates, and the impacts of changes in photolysis rates on ozone production and destruction rates in a polluted urban environment like Houston, Texas. During the TexAQS-II Radical and Aerosol Measurement Project the combined cloud and aerosol effects reduced j(NO2) photolysis frequencies by nominally 17%, while aerosols reduced j(NO2) by 3% on six clear sky days. Reductions in actinic flux due to attenuation by clouds and aerosols correspond to reduced net ozone formation rates with a nearly one-to-one relationship. The overall reduction in the net ozone production rate due to reductions in photolysis rates by clouds and aerosols was approximately 8 ppbv h?1. 相似文献
70.
Luke D. Ziemba Jack E. Dibb Robert J. Griffin Casey H. Anderson Sallie I. Whitlow Barry L. Lefer Bernhard Rappenglück James Flynn 《Atmospheric environment (Oxford, England : 1994)》2010,44(33):4081-4089
Nitrous acid (HONO), nitric acid (HNO3), and organic aerosol were measured simultaneously atop an 18-story tower in Houston, TX during August and September of 2006. HONO and HNO3 were measured using a mist chamber/ion chromatographic technique, and aerosol size and chemical composition were determined using an Aerodyne quadrupole aerosol mass spectrometer. Observations indicate the potential for a new HONO formation pathway: heterogeneous conversion of HNO3 on the surface of primary organic aerosol (POA). Significant HONO production was observed, with an average of 0.97 ppbv event?1 and a maximum increase of 2.2 ppb in 4 h. Nine identified events showed clear HNO3 depletion and well-correlated increases in both HONO concentration and POA-dominated aerosol surface area (SA). Linear regression analysis results in correlation coefficients (r2) of 0.82 for HONO/SA and 0.92 for HONO/HNO3. After correction for established HONO formation pathways, molar increases in excess HONO (HONOexcess) and decreases in HNO3 were nearly balanced, with an average HONOexcess/HNO3 value of 0.97. Deviations from this mole balance indicate that the residual HNO3 formed aerosol-phase nitrate. Aerosol mass spectral analysis suggests that the composition of POA could influence HONO production. Several previously identified aerosol-phase PAH compounds were enriched during events, suggesting their potential importance for heterogeneous HONO formation. 相似文献