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101.
The fate, effects, and potential environmental risks of ethylene glycol (EG) in the environment were examined. EG undergoes rapid biodegradation in aerobic and anaerobic environments (approximately 100% removal of EG within 24 h to 28 days). In air, EG reacts with photo-chemically produced hydroxyl radicals with a resulting atmospheric half-life of 2 days. Acute toxicity values (LC(50)s and EC(50)s) were generally >10,000 mg/l for fish and aquatic invertebrates. The data collectively show that EG is not persistent in air, surface water, soil, or groundwater, is practically non-toxic to aquatic organisms, and does not bioaccumulate in aquatic organisms. Potential long-term, quasi-steady state regional concentrations of EG estimated with a multi-media model for air, water, soil, and sediment were all less than predicted no effect concentrations (PNECs). 相似文献
102.
103.
The Passenger Pigeon (Ectopistes migratorius) was a social breeder, and it has been suggested that the species experienced functional extinction, defined as a total reproductive failure, prior to its actual extinction in the early years of the 20th century. We applied a novel randomization test based on the relative times of the most recent egg‐ and skin‐specimen sightings (i.e., recorded date of specimen collection) to test for functional extinction. For a total of 6 eggs and 27 skins, the observed significance level was 0.38, which indicated that the species did not become functionally extinct. Thus, proposals to reverse its rapid decline in the late 19th century could have been successful. 相似文献
104.
Sebastian Theis Jonathan L.W. Ruppert Karling N. Roberts Charles K. Minns Marten Koops Mark S. Poesch 《Conservation biology》2020,34(1):41-53
Land-use change via human development is a major driver of biodiversity loss. To reduce these impacts, billions of dollars are spent on biodiversity offsets. However, studies evaluating offset project effectiveness that examine components such as the overall compliance and function of projects remain rare. We reviewed 577 offsetting projects in freshwater ecosystems that included the metrics project size, type of aquatic system (e.g., wetland and creek), offsetting measure (e.g., enhancement, restoration, and creation), and an assessment of the projects’ compliance and functional success. Project information was obtained from scientific and government databases and gray literature. Despite considerable investment in offsetting projects, crucial problems persisted. Although compliance and function were related to each other, a high level of compliance did not guarantee a high degree of function. However, large projects relative to area had better function than small projects. Function improved when projects targeted productivity or specific ecosystem features and when multiple complementary management targets were in place. Restorative measures were more likely to achieve targets than creating entirely new ecosystems. Altogether the relationships we found highlight specific ecological processes that may help improve offsetting outcomes. 相似文献
105.
R.E. Wilkinson J.J. Roberts 《Journal of environmental science and health. Part. B》2013,48(3):591-598
Abstract Wheat (Triticum aestivum L.) trichomes influence wheat leaf rust (Puccinia recondita Rob. ex Desm.) germling elongation as a function of the external element (i.e. ‐ Ca, Si, P, CI) concentration. Basal cells of multicellular trichomes have a high Ca content; and, Ca2+ has been shown to inhibit elongation of primary roots. Evaluation of epicuticular wax composition in the intracellular areas of epidermal cells might explain the disorganized growth in those locations. 相似文献
106.
William F. Ryan Bruce G. Doddridge Russell R. Dickerson Raymond M. Morales Kristen A. Hallock Paul T. Roberts 《Journal of the Air & Waste Management Association (1995)》2013,63(9):786-797
ABSTRACT Ozone (O3) concentrations in the Baltimore-Washington (B-W) metropolitan area frequently exceed the National Ambient Air Quality Standard (NAAQS) in the summer months. The most extreme O3 events occur in multi-day high O3 episodes.1 These events can be regional in scale, with O3 concentrations exceeding the NAAQS at numerous locations along the eastern U.S. seaboard, and are typically associated with slow-moving or stagnant high pressure systems.2-5 In the B-W region, the most extreme events typically occur with surface high pressure overhead or just west of the region and an upper air high-pressure area (ridge) to the west or northwest.1 Besides providing conditions conducive to local O3 production (subsidence and strong low-level inversions, weak horizontal winds, little cloud cover), this weather pattern may also result in transport of O3 and its precursors from heavily industrialized areas west and north of the B-W region. In this paper, observations and back trajectories made during the severe regional O3 event of July 12-15, 1995, are used to confirm the hypothesis that significant regional-scale transport of O3 and its precursors occur during extreme O3 events of the standard type in the B-W area. 相似文献
107.
J. C. Xavier M. Louzao S. E. Thorpe P. Ward C. Hill D. Roberts J. P. Croxall R. A. Phillips 《Marine Biology》2013,160(7):1597-1606
Shifts in the diet of top predators can be linked to changes in environmental conditions. In this study, we tested relationships between environmental variation and seasonal changes in diet of a top predator, the grey-headed albatross Thalassarche chrysostoma, breeding at Bird Island, South Georgia in an austral summer of 1999/2000. Oceanographic conditions in that year around South Georgia were abnormal (i.e. anomalously high sea surface temperature to a relative 19-year long-term mean). The diet of grey-headed albatrosses showed high seasonal variation, shifting from cephalopods (42.9 % by mass) in late February to Antarctic krill Euphausia superba (58.3 %) in late April, and grey-headed albatrosses breeding performance was low (16.8 %). This study shows these albatrosses did not manage to find sufficient alternative prey and highlight the risk to top predators if there is an increase in the frequency or severity of food shortages in Antarctic waters. 相似文献
108.
The interaction of a suite of predators with mating and spawning chokka squid (Loligo vulgaris reynaudii) was studied at inshore (<50 m) spawning grounds off South Africa. This study provides the first detailed records of predator-prey interactions of squids on their spawning grounds and is the first attempt to time disruptions caused by predators to the egg-laying behaviour of squids, thereby quantifying the perceived threat to the prey. The squids are focused on mate choice and reproduction while they aggregate over egg beds and they may be more vulnerable to predation than at other times. Their vulnerability to different predators in the field is examined and the tactics used against different predatory species are illustrated using recordings made with underwater video cameras. Predators recorded included two cephalopods (Octopus vulgaris and L. v. reynaudii), five teleosts (Pagellus bellotii natalensis, Spondyliosoma emarginatum, Pachymetopon aeneum, Cheimerius nufar and Pomatomus saltatrix), seven chondrichthyians (Squalus megalops, Mustelus mustelus, Carcharias taurus, Dasyatis brevicaudata, Gymnura natalensis, Poroderma africanum and P. pantherinum) and three marine mammals (Arctocephalus puscillus, Tursiops aduncus and Delphinus delphis). Analysis of behavioural interactions between predators and prey showed that predator disruption of egg laying may be quantified in terms of time. Marine mammals caused the most acute disruption, whereas other taxa had more chronic disruption effects because they spent more time on the spawning grounds. During November 1995, the suite of predators changed during the course of a 2-day period of underwater video recording, possibly because of an increase in water temperature. The hypothesis that predators would be concentrated around a spawning aggregation was tested by surveying the spawning ground using an underwater camera towed by a boat navigating with differential GPS. The results supported the hypothesis because predators were located only around the spawning sites. The serial spawning of chokka squids in recently upwelled water may reduce predation pressure. Furthermore, it may be difficult for predators to predict the specific spawning site on a particular day because squids disperse away from egg beds at night and use numerous spawning sites along the coast. 相似文献
109.
110.
Marc C. Coles‐Ritchie David W. Roberts Jeffrey L. Kershner Richard C. Henderson 《Journal of the American Water Resources Association》2007,43(3):731-743
Abstract: A method was developed to characterize ecological integrity of riparian sites based on the abundance of hydric species. This wetland index can be calculated with species data, or with community type data as performed here. Classified riparian community types were used to describe vegetation at 14 livestock exclosures and adjacent grazed areas. Community type wetland index values were generated and used to calculate site wetland index values. It was hypothesized that removal of livestock would result in higher wetland index values because of release from herbivory and decreased physical disturbance of vegetation, streambanks, and soil. The wetland index for exclosures was about 12% higher than grazed sites; differences were statistically significant (p < 0.01) based on paired t‐tests. The increase in hydric vegetation after livestock exclusion may have contributed to the greater bank stability (p = 0.002) and smaller width‐to‐depth ratio (p = 0.005) in exclosures. Challenges were encountered in using community types to describe and compare site vegetation, which could be avoided with species data collection. The wetland index can be a tool to monitor sites over time, compare sites with similar environments, or compare sites for which environmental differences can be accounted. 相似文献