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91.
As coastal populations expand, demands for recreational opportunities on beaches and coastal dunes grow correspondingly. Although
dunes are known to be sensitive to direct human disturbance and provide irreplaceable ecosystem services (e.g. erosion control,
critical habitat and nesting sites), dunes serve as campsites for large numbers of people (∼90,000 p.a.) on the ocean-exposed
shores of Fraser Island, Australia. Campsites are located in the established dunes and can only be accessed with 4WD vehicles
along tracks cut directly from the beach through the foredunes. Here we quantified the extent of physical damage to foredunes
caused by this practice, and tested whether human-induced physical changes to foredunes translate into biological effects.
Of the 124 km of ocean-exposed beaches, 122 km (98%) are open to vehicles driven on the beaches, and camping zones cover 28.7
km or 23% of the dunes. A total of 235 vehicle tracks are cut across the foredunes at an average density of eight tracks per
km of beach. These tracks have effectively destroyed one-fifth (20.2%) of the dune front in camping zones, deeply incising
the dune-beach interface. There is evidence of accelerated erosion and shoreline retreat centred around vehicle tracks, resulting
in a “scalloping” of the shoreline. No dune vegetation remains in the tracks and the abundance of ghost crabs (Ocypode spp.) is significantly reduced compared with the abutting dunes. Because current levels of environmental change caused by
dune camping may not be compatible with the sustainable use of coastal resources and conservation obligations for the island
(listed as a World Heritage Area and gazetted as a National Park), restoration and mitigation interventions are critical.
These will require spatial prioritisation of effort, and we present a multi-criteria ranking method, based on quantitative
measures of environmental damage and ecological attributes, to objectively target rehabilitation and conservation measures.
Ultimately, coastal management needs to develop and implement strategies that reconcile demands for human recreation, including
beach camping, with conservation of coastal dune ecosystems. 相似文献
92.
Luke Christopher Evans Matthew P. Greenwell Victoria L. Boult Thomas Frederick Johnson 《Conservation biology》2023,37(4):e14070
Social media is an arena of debate for contentious political and social topics. One conservation topic debated online is the acceptability of trophy hunting, a debate that has implications for national and international policy. We used a mixed-methods approach (grounded theory and quantitative clustering) to identify themes in the trophy hunting debate on Twitter. We examined commonly co-occurring categories that describe people's stances on trophy hunting. We identified 12 categories and 4 preliminary archetypes opposing trophy hunting—activism, scientific, condemning, and objecting—whose opposition derived from different moral reasoning. Few tweets (22) in our sample of 500 supported trophy hunting, whereas 350 opposed it. The debate was hostile; 7% of tweets in our sample were categorized as abusive. Online debates can be unproductive, and our findings may be important for stakeholders wishing to effectively engage in the trophy hunting debate on Twitter. More generally, we contend that because social media is increasingly influential, it is important to formally contextualize public responses to contentious conservation topics in order to aid communication of conservation evidence and to integrate diverse public perspectives in conservation practice. 相似文献
93.
94.
Luke Holmes 《Environmental pollution (Barking, Essex : 1987)》2009,157(12):3440-3444
Leaching of Cu and Zn from a composite of discarded antifouling paint residues ([Cu] = 288 mg g−1; [Zn] = 96 mg g−1) into natural sea water has been studied over a period of 75 h. Total Cu and Zn were released according to a pseudo first-order reaction, with rate constants on the order of 0.3 and 2.5 (mg L−1)−1 h−1, respectively, and final concentrations equivalent to the dissolution of about 8 and 2% of respective concentrations in the composite. Time-distributions of hydrophobic metals, determined by solid phase extraction-methanol elution, were more complex. Net release of hydrophobic Cu was greater in the absence of light than under a sequence of light-dark cycles; however, hydrophobic Zn release was not detected under the former conditions but contributed up to 50% of total aqueous Zn when light was present. These observations are interpreted in terms of the relative thermodynamic and photolytic stabilities of biocidal pyrithione complexes. 相似文献
95.
John L. Pearce Stephen L. Rathbun Manuel Aguilar-Villalobos Luke P. Naeher 《Atmospheric environment (Oxford, England : 1994)》2009,43(12):2060-2069
Advancing the understanding of spatiotemporal aspects of air pollution in the urban environment is an area where improved methods can be of great benefit to exposure assessment and policy support. This paper explores the potential of a technique known as kriging with external drift (KED) to provide high resolution maps of fine particulate matter for a downtown region of Cusco, Peru. There were three stages in this research. The first was to conduct a pilot level monitoring campaign to investigate ambient, regional, and street-level air pollutant concentrations for particulate matter (PM2.5, PM10) and carbon monoxide (CO) in the Province of Cusco. The second was to compile observations within a geographic information system (GIS) in order to characterize the proximal effect of the local transportation network, elevation, and land use classifications on PM2.5. Third, regression, ordinary kriging and kriging with external drift were used to model PM2.5 for three select time periods during a 24-h day. Statistical evaluations indicate kriging with external drift resulted in the strongest models explaining 64% of variability seen with morning particle concentrations, 25% for afternoon particles, and 53% in evening particles. These models capture spatial and temporal variability for air pollution in Cusco. These variations seem to be influenced, to varying degrees, by elevation, meteorological conditions, spatial location, and transportation characteristics. In conclusion, combining GIS, meteorological data and geostatistics proved to be a complementary suite of tools for incorporating spatiotemporal analysis into the air quality assessment. 相似文献
96.
Luke D. Knibbs Richard J. de Dear Lidia Morawska Kerrie L. Mengersen 《Atmospheric environment (Oxford, England : 1994)》2009,43(22-23):3510-3519
The human health effects following exposure to ultrafine (<100 nm) particles (UFPs) produced by fuel combustion, while not completely understood, are generally regarded as detrimental. Road tunnels have emerged as locations where maximum exposure to these particles may occur for the vehicle occupants using them. This study aimed to quantify and investigate the determinants of UFP concentrations in the 4 km twin-bore (eastbound and westbound) M5 East tunnel in Sydney, Australia. Sampling was undertaken using a condensation particle counter (CPC) mounted in a vehicle traversing both tunnel bores at various times of day from May through July, 2006. Supplementary measurements were conducted in February, 2008. Over three hundred transects of the tunnel were performed, and these were distributed evenly between the bores. Additional comparative measurements were conducted on a mixed route comprising major roads and shorter tunnels, all within Sydney. Individual trip average UFP concentrations in the M5 East tunnel bores ranged from 5.53 × 104 p cm?3 to 5.95 × 106 p cm?3. Data were sorted by hour of capture, and hourly median trip average (HMA) UFP concentrations ranged from 7.81 × 104 p cm?3 to 1.73 × 106 p cm?3. Hourly median UFP concentrations measured on the mixed route were between 3.71 × 104 p cm?3 and 1.55 × 105 p cm?3. Hourly heavy diesel vehicle (HDV) traffic volume was a very good determinant of UFP concentration in the eastbound tunnel bore (R2 = 0.87), but much less so in the westbound bore (R2 = 0.26). In both bores, the volume of passenger vehicles (i.e. unleaded gasoline-powered vehicles) was a significantly poorer determinant of particle concentration. When compared with similar studies reported previously, the measurements described here were among the highest recorded concentrations, which further highlights the contribution road tunnels may make to the overall UFP exposure of vehicle occupants. 相似文献
97.
Precious Sibiya Luke Chimuka Ewa Cukrowska Hlanganani Tutu 《Environmental monitoring and assessment》2013,185(7):5537-5550
A microwave-assisted extraction (MAE) method was verified and applied for the extraction of polycyclic aromatic hydrocarbons (PAHs) in sediment samples. Soxhlet extraction was used as the reference method. The optimum MAE was carried out with 20 mL of hexane/acetone (1:1, v/v) mixture in a 1-g sample at 250 W for 20 min. Soxhlet extraction was carried out with 250 mL of dichloromethane:hexane (1:1, v/v) mixture in a 15-g sample for 24 h in a water bath maintained at 60 °C. The collected extracts were both cleaned up, reduced to 1 mL under nitrogen and then injected into an HPLC fluorescence. To increase the sample throughput, simultaneous MAE was performed. The obtained percentage recoveries ranged from 61 to 93 and 88–98 for MAE and SE, respectively. The optimised MAE method was validated using certified reference material. It was then applied to real sediment samples from in and around the greater Johannesburg area. The sediments from Jukskei River were found to be the most polluted while Hartbeespoort Dam sediments were found to be least polluted. The overall order of concentrations for the studied PAHs per site was as follows: Jukskei River?>?Kempton Park?>?Centurion Dams?>?Natalspruit River (PIT)?>?Hartbeespoort Dam. 相似文献
98.
Water-soluble inorganic pollutants may constitute an environmental toxicity problem if their movement through soils and potential transfer to plants or groundwater is not arrested. The capability of biochar to immobilise and retain arsenic (As), cadmium (Cd) and zinc (Zn) from a multi-element contaminated sediment-derived soil was explored by a column leaching experiment and scanning electron microanalysis (SEM/EDX). Sorption of Cd and Zn to biochar’s surfaces assisted a 300 and 45-fold reduction in their leachate concentrations, respectively. Retention of both metals was not affected by considerable leaching of water-soluble carbon from biochar, and could not be reversed following subsequent leaching of the sorbant biochar with water at pH 5.5. Weakly water-soluble As was also retained on biochar’s surface but leachate concentrations did not duly decline. It is concluded that biochar can rapidly reduce the mobility of selected contaminants in this polluted soil system, with especially encouraging results for Cd. 相似文献
99.
Slow recovery of tropical old‐field rainforest regrowth and the value and limitations of active restoration 下载免费PDF全文
Luke P. Shoo Kylie Freebody John Kanowski Carla P. Catterall 《Conservation biology》2016,30(1):121-132
There is current debate about the potential for secondary regrowth to rescue tropical forests from an otherwise inevitable cascade of biodiversity loss due to land clearing and scant evidence to test how well active restoration may accelerate recovery. We used site chronosequences to compare developmental trajectories of vegetation between self‐organized (i.e., spontaneous) forest regrowth and biodiversity plantings (established for ecological restoration, with many locally native tree species at high density) in the Australian wet tropics uplands. Across 28 regrowth sites aged 1–59 years, some structural attributes reached reference rainforest levels within 40 years, whereas wood volume and most tested components of native plant species richness (classified by species’ origins, family, and ecological functions) reached less than 50% of reference rainforest values. Development of native tree and shrub richness was particularly slow among species that were wind dispersed or animal dispersed with large (>10 mm) seeds. Many species with animal‐dispersed seeds were from near‐basal evolutionary lineages that contribute to recognized World Heritage values of the study region. Faster recovery was recorded in 25 biodiversity plantings of 1–25 years in which wood volume developed more rapidly; native woody plant species richness reached values similar to reference rainforest and was better represented across all dispersal modes; and species from near‐basal plant families were better (although incompletely) represented. Plantings and regrowth showed slow recovery in species richness of vines and epiphytes and in overall resemblance to forest in species composition. Our results can inform decision making about when and where to invest in active restoration and provide strong evidence that protecting old‐growth forest is crucially important for sustaining tropical biodiversity. 相似文献
100.
Surface waves and roughness in self-aerated supercritical flow 总被引:1,自引:1,他引:1
In high-velocity open channel flows, free-surface aeration is commonly observed. The effects of surface waves on the air–water
flow properties are tested herein. The study simulates the air–water flow past a fixed-location phase-detection probe by introducing
random fluctuations of the flow depth. The present model yields results that are close to experimental observations in terms
of void fraction, bubble count rate and bubble/droplet chord size distributions. The results show that the surface waves have
relatively little impact on the void fraction profiles, but that the bubble count rate profiles and the distributions of bubble
and chord sizes are affected by the presence of surface waves. 相似文献