Hydrology, roadway traffic conditions, and atmospheric deposition are three essential data categories for the planning and implementation of highway-runoff monitoring and characterization programs. Causal variables pertaining to each data category could be site specific but have been shown to correlate with runoff pollutant loads. These data categories were combined to derive statistical relationships for characterization and prioritization of the respective pollutant loads at highway runoff sites. Storm runoff data of total suspended solids (TSS), total dissolved solid (TDS), chemical oxygen demand (COD), total Kjeldahl nitrogen (TKN) and total phosphorus (TP) collected from three highway sites in Charlotte, North Carolina, USA, were used to illustrate the development of site-specific highway-runoff pollutant loading models. This unified methodology provides a basis for initial assessment of the pollutant-constituent loads from highway runoff using hydrologic component variables. Improved reliability is achievable when additional traffic and/or atmospheric component variables are incorporated into the basic hydrologic regression model. In addition, operational guidance is suggested for implementing highway-runoff monitoring programs that are subject to sampling and resources constraints. 相似文献
The SARS-CoV-2 novel coronavirus pandemic has revealed many scientific, social, and institutional challenges required to improve the health and wellbeing of individuals stricken by this disease. While organizations and governing institutions have risen to the task to concurrently prepare for and respond to this pandemic under conditions of high uncertainty and extreme pressure, another important aspect of this viral infection deserves attention and is not being fully considered, that is early intervention strategies and structured tools for individuals who test positive for the virus and begin developing symptoms. For those whose infection is progressing, we describe the potential benefits of a self-monitoring tool for use in combination with physician directed early medical interventions to slow COVID-19 progression.
The reintroduction of large predators provides a framework to investigate responses by prey species to predators. Considerable research has been directed at the impact that reintroduced wolves (Canis lupus) have on cervids, and to a lesser degree, bovids, in northern temperate regions. Generally, these impacts alter feeding, activity, and ranging behavior, or combinations of these. However, there are few studies on the response of African bovids to reintroduced predators, and thus, there is limited data to compare responses by tropical and temperate ungulates to predator reintroductions. Using the reintroduction of lion (Panthera leo) into the Addo Elephant National Park (AENP) Main Camp Section, South Africa, we show that Cape buffalo (Syncerus caffer) responses differ from northern temperate ungulates. Following lion reintroduction, buffalo herds amalgamated into larger, more defendable units; this corresponded with an increase in the survival of juvenile buffalo. Current habitat preference of buffalo breeding herds is for open habitats, especially during the night and morning, when lion are active. The increase in group size and habitat preference countered initial high levels of predation on juvenile buffalo, resulting in a return in the proportion of juveniles in breeding herds to pre-lion levels. Our results show that buffalo responses to reintroduced large predators in southern Africa differ to those of northern temperate bovids or cervids in the face of wolf predation. We predict that the nature of the prey response to predator reintroduction is likely to reflect the trade-off between the predator selection and hunting strategy of predators against the life history and foraging strategies of each prey species. 相似文献
Intensive fishing can cause dramatic, long-lasting shifts in benthic habitat. This study used three approaches to test whether
overharvesting of blacklip abalone (Haliotis rubra) can cause a shift in benthic habitat to a configuration that is unsuitable for abalone, on the east coast of Tasmania, Australia.
After 18 months of removing abalone from rocks, encrusting red algae (ERA) became overgrown by filamentous and foliose algae,
sessile invertebrates and accumulated sediment. The differences in the community composition between locations, sites nested
within locations and rocks were minor. Throughout the study, abalone were largely associated with areas of rock covered in
ERA but avoided other habitats. A transplant experiment demonstrated that abalone preferred areas of rock covered in ERA but
move away from overgrown rocks. These results suggest overharvesting of abalone results in a shift to benthic habitat poorly
preferred by abalone. This could form a positive feedback loop that limits recovery of abalone populations and ERA. 相似文献
Background Cobalt cyanide complexes often result when ore is treated with cyanide solutions to extract gold and other metals. These have
recently been discovered in low but significant concentrations in effluents from gold leach operations. This study was conducted
to determine the potential toxicity of cobalt-cyanide complexes to freshwater organisms and the extent to which ultraviolet
radiation (UV) potentiates this toxicity. Tests were also conducted to determine if humic acids or if adaptation to UV influenced
sensitivity to the cyanide complexes.
Methods Rainbow trout (Oncorhynchus mykiss), Daphnia magna, and Ceriodaphnia dubia were exposed to potassium hexacyanocobaltate in the presence and absence of UV radiation, in the presence and absence of
humic acids. Cyano-cobalt exposures were also conducted with C. dubia from cultures adapted to elevated UV.
Results With an LC50 concentration of 0.38 mg/L, cyanocobalt was over a 1000 times more toxic to rainbow trout in the presence of
UV at a low, environmentally relevant irradiance level (4 μW/cm2 as UVB) than exposure to this compound in the absence of UV with an LC50 of 112.9 mg/L. Toxicity was immediately apparent,
with mortality occurring within an hour of the onset of exposure at the highest concentration. Fish were unaffected by exposure
to UV alone. Weak-acid dissociable cyanide concentrations were observed in irradiated aqueous solutions of cyanocobaltate
within hours of UV exposure and persisted in the presence of UV for at least 96 hours, whereas negligible concentrations were
observed in the absence of UV. The presence of humic acids significantly diminished cyanocobalt toxicity to D. magna and reduced mortality from UV exposure. Humic acids did not significantly influence survival among C. dubia. C. dubia from UV-adapted populations were less sensitive to metallocyanide compounds than organisms from unadapted populations.
Conclusions The results indicate that metallocyanide complexes may pose a hazard to aquatic life through photochemically induced processes.
Factors that decrease UV exposure such as dissolved organic carbon or increased pigmentation would diminish toxicity. 相似文献
The range of red deer populations in the Scottish Highlands can cover several different landholdings (estates), many of which derive their income primarily from the private hunting (stalking) of stags. The deer belong to nobody and their seasonal movement does not respect the boundaries of individual estates, but a 'rule of capture' does apply as, once shot, the deer become the property of the estate owner. This paper argues that deer populations would best be managed as a common property resource. Indeed, for this reason, the Deer Commission for Scotland has encouraged owners to form Deer Management Groups. These groups are now able to utilize a computer program that models the relationship between grazing quality and population dynamics. However, drawing upon examples from the Western Highlands, the paper finds that common property management must overcome incentives to behave strategically that arise from the characteristics of flow and storage of the resource. The problem is aggravated by the degradation of the habitat that has occurred over centuries. This often means that the resource is below its optimum in terms of stag numbers and quality. Scientific models are an important contribution, but only reduce the environmental uncertainty. Their full potential can only be realized if all landowners are obliged to actively engage in common property management. 相似文献
Carbon cycling analysis is presented as a means for assessing anthropogenic perturbations in an ecosystem. Data from oligotrophic, eutrophic, and dystrophic (bog) lakes are used to show general trends in the lacustrine carbon cycle. The oligotrophic lake is an unstressed system and the eutrophic lake is under nutrient enrichment with high algal standing crops and productivity. The bog lake is a pH-stressed environment that is primarily a grazing ecosystem. It is hoped that a more effective environmental impact assessment will result from the use of carbon cycling as a unifying concept in ecosystem analysis. 相似文献