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151.
La Sala LF Petracci PF Smits JE Botté S Furness RW 《Environmental monitoring and assessment》2011,181(1-4):1-11
Mercury (Hg) exposure was investigated through feathers of Olrog's Gull and related to health parameters in adults (hematocrit, total plasma proteins, morphometric measures, sex) and chicks (hematocrit, total plasma proteins, immunoglobulins G and M) from a colony located in estuary of Bahía Blanca, Argentina. Mercury concentrations were 5.50 ± 2.59 μg g?1 (n = 44) in live adults, 1.85 ± 0.45 μg g?1 (n = 45) in live chicks and 1.81 ± 0.41 μg g?1 (n = 41) in dead chicks. Large differences were observed between live adults and live or dead chicks and small differences between live and dead chicks. In the adults, the sex of the birds was the variable that best explained Hg concentrations. Male birds had higher concentrations than females; this suggests that the clutch provides a sink for mercury during egg laying. Hg concentrations in both adults and live chicks were associated with higher hematocrits. This could be associated with upregulated erythropoiesis to compensate for increased rate of destruction of prematurely senescent, Hg-contaminated erythrocytes. Based on our results, on the levels of Hg pollution in the past in the study area, and on the dietary specialization of Olrog's Gull, we must be vigilant about potential negative effects of Hg pollution on this population and recommend continued monitoring on this threatened species. 相似文献
152.
Sandra K. Poppenga Dean B. Gesch Bruce B. Worstell 《Journal of the American Water Resources Association》2013,49(2):371-389
Abstract: The 1:24,000‐scale high‐resolution National Hydrography Dataset (NHD) mapped hydrography flow lines require regular updating because land surface conditions that affect surface channel drainage change over time. Historically, NHD flow lines were created by digitizing surface water information from aerial photography and paper maps. Using these same methods to update nationwide NHD flow lines is costly and inefficient; furthermore, these methods result in hydrography that lacks the horizontal and vertical accuracy needed for fully integrated datasets useful for mapping and scientific investigations. Effective methods for improving mapped hydrography employ change detection analysis of surface channels derived from light detection and ranging (LiDAR) digital elevation models (DEMs) and NHD flow lines. In this article, we describe the usefulness of surface channels derived from LiDAR DEMs for hydrography change detection to derive spatially accurate and time‐relevant mapped hydrography. The methods employ analyses of horizontal and vertical differences between LiDAR‐derived surface channels and NHD flow lines to define candidate locations of hydrography change. These methods alleviate the need to analyze and update the nationwide NHD for time relevant hydrography, and provide an avenue for updating the dataset where change has occurred. 相似文献
153.
Changing land use in the tropics has resulted in vast areas of damaged and degraded lands where biodiversity has been reduced. The majority of research on biodiversity has been focused on population and community dynamics and has rarely considered the ecosystem processes that are intimately related. We present a framework for examining the effects of changes in biodiversity on ecosystem function in natural, managed, and damaged tropical forests. Using a whole-ecosystem approach, the framework identifies key nutrient and energy cycling processes and critical junctures or pathways, termed interfaces, where resources are concentrated and transferred between the biotic and abiotic components of the ecosystem. Processes occurring at these interfaces, and the organisms or attributes participating in these processes, exert a strong influence on ecosystem structure. We use examples from Puerto Rico, Southern China, Dominica, and Nicaragua to illustrate how the functional diversity framework can be applied to critically examine the effects of changes in biodiversity on ecosystem function, and the relative success or failure of rehabilitation strategies. The few available data suggest that functional diversity, and not just species richness, is important in maintaining the integrity of nutrient and energy fluxes. High species richness, however, may increase ecosystem resiliency following disturbance by increasing the number of alternative pathways for the flow of resources. We suggest ways in which the framework of functional diversity can be used to design research to examine the effects of changes in biodiversity on ecosystem processes and in the design and evaluation of ecosystem management and land rehabilitation projects in the tropics. 相似文献
154.
155.
M. Anwar H. Khan M. M. Nazmul Hoque S. Shamsul Alam M. J. Ashfol Graham Nickless Dudley E. Shallcross 《环境科学学报(英文版)》2011,23(1):60-64
Night-time OH levels have been determined for UK urban surface environments using two methods, the decay and steady state
approximation methods. Measurement data from the UK National Environmental Technology Centre archive for four urban sites
(Bristol, Harwell, London Eltham and Edinburgh) over the time period of 1996 to 2000 have been used in this study. Three reactive
alkenes, namely isoprene, 1,3-butadiene and trans-2-pentene were chosen for the calculation of OH levels by the decay method. Hourly
measurements of NO, NO2, O3, CO and 20 VOCs were used to determine night-time OH level using the steady state approximation
method. Our results showed that the night-time OH levels were in the range of 1 105–1 106 molecules/cm3 at these four urban sites in
the UK. The application of a t-test of these analyses indicated that except Bristol, there was no significant di erence between the OH
levels found from the decay and steady state approximation methods. Night-time levels of the OH radical appeared to peak in summer
and spring time tracking the night-time O3 levels which also passed through a maximum at this time. 相似文献
156.
Jonathan Winsten Sarah Walker Sandra Brown Sean Grimland 《Mitigation and Adaptation Strategies for Global Change》2011,16(8):925-942
The Regional Greenhouse Gas Initiative for the northeastern states of the U.S. allows for terrestrial carbon (C) sequestration
offsets generated by afforestation activities only. This paper estimates the maximum potential quantity and associated costs
of increasing the storage of carbon by afforestation of existing agricultural land in the 11 states of the Northeast United
States. The focus of the work was to describe location, the quantity, and at what cost it would be economically attractive
to shift agricultural production to afforestation to increase carbon storage in the region. Widely available data sets were
used to (1) identify spatially-explicit areas for lower costs carbon offsets and (2) estimate carbon supply curves related
to afforestation of agricultural land over three time periods (10, 20, and 40 years). Carbon accumulation and total carbon
offset project costs were estimated at a county scale and combined to identify expected costs per ton of carbon dioxide equivalents
(CO2e). Large variation in estimated costs per ton of CO2e are driven by varying carbon accumulation potentials and opportunity costs of taking land out of agricultural production,
as well as the duration of the project activity. Results show that the lowest cost carbon offset projects will be in certain
counties of Maine, Vermont, and New York. Pasture land, with lower opportunity costs, generally presents the opportunity for
lower cost carbon offset projects relative to cropland. This analysis estimates that afforestation of pasture land in the
northeast will not become economically attractive until the price rises above 10 per metric tonne (MT) CO < sub > 2 < /sub > e and that up to 583 million MT could be economically sequestered if the price were to rise to10 per metric tonne (MT) CO2e and that up to 583 million MT could be economically sequestered if the price were to rise to 50 per MT CO2e, based on a 40-year project life. With regard to cropland in the northeast, afforestation does not become economically advantageous
for land owners until the price rises above $40 per MT CO2e. It is estimated that up to 487,000 MT could be sequestered from cropland if the price were to rise to $40 per MT CO2e. It is estimated that up to 487,000 MT could be sequestered from cropland if the price were to rise to 50 per MT CO2e, based on a 40-year project life. 相似文献
157.
Almeida Aleska Kaufmann de Almeida Isabel Kaufmann Guarienti José Antonio Gabas Sandra Garcia 《Environmental science and pollution research international》2022,29(6):8126-8172
Environmental Science and Pollution Research - The time of concentration (Tc) is the main hydrological parameter used to characterize the response of a given Hydrological Response Unit (HRU) to a... 相似文献
158.
Stephan Pflugmacher Kyu-Sang Kwon Seungyun Baik Sanghum Kim Sandra Kühn Maranda Esterhuizen-Londt 《毒物与环境化学》2016,98(2):241-259
Due to increased pollution of potable water sources as a consequence of eutrophication and anthropogenic xenobiotics, sustainable water purification is an essential concern. Therefore, the Green Liver System, a natural, economic and sustainable water purification system employing the biotransformation capabilities of aquatic plants, was developed. To expand the capacities and applications of this system, new aquatic plants are continually evaluated for their potential to remediate various aquatic pollutants. In this study, the potential of Cladophora glomerata to internalize cyanotoxins, microcystins (MCs) and anatoxin-a, and consequently its ability to cope with the subsequent oxidative stress associated with toxin-uptake were investigated. C. glomerata was able to take up all three of the tested MC congeners as well as anatoxin-a, similarly to previous toxin internalizations reported for aquatic plants such as Ceratophyllum demersum, Myriophyllum spicatum and Hydrilla versiculata. The antioxidative stress defense of C. glomerata proved to efficiently endure the toxin-uptake with no adverse effects. Subsequently, the uptake potential of C. glomerata was investigated at lab-scale by exposure to the three MC congeners and anatoxin-a collectively. After a period of seven days, 95–97% of the MCs and 100% of anatoxin-a were removed from the exposure media. C. glomerata therefore, is a suitable candidate to be incorporated in future Green Liver Systems. 相似文献
159.
The possibility of riboflavin sensitized photo‐oxidation of polychlorinated pesticides was investigated. The dye proved to be an inefficient sensitizer for that purpose, when irradiated with visible light, in aereated aqueous solutions. A quenching of singlet and triplet excited states of the chromophore (depending on the concentrations of the quencher) is responsible for this failure in the photo‐degradation of the pesticides, which resulted easily oxidizable, via singlet oxygen mechanism, when proflavine was employed as a sensitizer. Parallel, and as a direct consequence, the rate of aerobic riboflavin photobleaching decreased drastically in the presence of the chlorophenols. The implication of our results on the inhibition of riboflavin degradation by the presence of chlorinated phenolic pesticides in the environment, is discussed, from the point of view of a kinetic and mechanistic study. 相似文献
160.
Fulvio Maffucci Ilaria D’Angelo Sandra Hochscheid Mariapia Ciampa Giovanni De Martino Andrea Travaglini Gianluca Treglia Flegra Bentivegna 《Marine Biology》2013,160(5):1097-1107
Sex ratios are a crucial parameter for evaluating population viability. In species with complex life history patterns and temperature sex determination mechanisms, such as the loggerhead turtle (Caretta caretta), sex ratios may vary within a population and among populations. In the Mediterranean, juvenile sex ratios appear to not differ significantly from 1:1, although estimates for hatchling sex ratios are highly female biased. The immigration of males from the Atlantic has been suggested as a possible cause of such variation. Here, we present results of a multi-year investigation (2000–2011) on the sex ratios of loggerhead turtles foraging along the south Tyrrhenian coast, Western Mediterranean, with the aim of providing a better understanding of the potentially underlying forces that drive regional and age-dependent differences in sex ratios. Sex was determined through visual examination of the gonads in 271 dead turtles (curved carapace length range 29.5–89 cm). A fragment of the mitochondrial DNA control region was sequenced from 61 specimens to characterise the demographic composition of this foraging assemblage by applying a many-to-many mixed stock analysis approach. No significant association was found between sex ratios and years or size classes, although the largest size was male biased. Juvenile sex ratio was 1.56:1, which was different from an even sex ratio but still less female biased than hatchling sex ratios from Mediterranean beaches. Results of the mixed stock analysis indicate that juvenile sex ratios in the Mediterranean are largely unaffected by immigration of Atlantic individuals into the basin, as previously suggested. Continued long-term monitoring of juvenile sex ratios is necessary to detect biologically significant sex ratio shifts in the Mediterranean loggerhead turtle population. 相似文献