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Hronn Egilsdottir Fanny Noisette Laure M.-L. J. Noël Jon Olafsson Sophie Martin 《Marine Biology》2013,160(8):2103-2112
Marine organisms inhabiting environments where pCO2/pH varies naturally are suggested to be relatively resilient to future ocean acidification. To test this hypothesis, the effect of elevated pCO2 was investigated in the articulated coralline red alga Corallina elongata from an intertidal rock pool on the north coast of Brittany (France), where pCO2 naturally varied daily between 70 and 1000 μatm. Metabolism was measured on algae in the laboratory after they had been grown for 3 weeks at pCO2 concentrations of 380, 550, 750 and 1000 μatm. Net and gross primary production, respiration and calcification rates were assessed by measurements of oxygen and total alkalinity fluxes using incubation chambers in the light and dark. Calcite mol % Mg/Ca (mMg/Ca) was analysed in the tips, branches and basal parts of the fronds, as well as in new skeletal structures produced by the algae in the different pCO2 treatments. Respiration, gross primary production and calcification in light and dark were not significantly affected by increased pCO2. Algae grown under elevated pCO2 (550, 750 and 1000 μatm) formed fewer new structures and produced calcite with a lower mMg/Ca ratio relative to those grown under 380 μatm. This study supports the assumption that C. elongata from a tidal pool, where pCO2 fluctuates over diel and seasonal cycles, is relatively robust to elevated pCO2 compared to other recently investigated coralline algae. 相似文献
155.
Scott Elliott Gerald E. Streit Jeffrey S. Gaffney James E. Bossert Michael Brown Jon Reisner Laurie A. McNair 《Environmental science and pollution research international》1999,6(2):103-105
The nerve agent sarin has recently been deployed by terrorists in a major city. The molecule is volatile and made its way
to many victims by passing as vapor through a highly reactive medium. Here we estimate rates and pathways for the removal
of gas phase sarin from a generalized urban atmosphere. Only information from the open scientific literature is used. By structure
reactivity comparisons with the organophosphorus pesticides, hydroxyl radical hydrogen abstraction may occur in as little
as one hour. Decomposition of side chains after hydroxyl attack leads to organic oxygenates which preserve the phosphonofluoridate
and so toxicity. The aqueous aerosol surface is contacted in minutes and offers access to a range of dissolved nucleophiles.
Substitution displaces the fluoride leaving group, giving safe phosphoric acid analogs. Because of uncertainties in the electron
distribution and in aqueous decay mechanisms, the time constants must be viewed as lower limits. 相似文献
156.
Li Maotian Finlayson Brian Webber Michael Barnett Jon Webber Sophie Rogers Sarah Chen Zhongyuan Wei Taoyuan Chen Jing Wu Xiaodan Wang Mark 《Regional Environmental Change》2017,17(4):1153-1161
Regional Environmental Change - Many of the world’s major cities are expected to face significant water shortages in coming decades, largely due to increased demand arising from economic and... 相似文献
157.
This paper studies the practice of semi-domestic reindeer (Rangifer t. tarandus) herding in Finnmark county in northern Norway. In this area, the Saami reindeer herders compete for space and grazing areas and keep large herds, while at the same time, the reindeer population is heavily exposed to carnivore predation by the lynx (Lynx lynx), the wolverine (Gulo gulo), and the golden eagle (Aquila chrysaetos). It is demonstrated that predation actually may improve the economic lot of livestock holders in this unmanaged local common setting. There are ecological as well as economic reasons as to why this happens. The ecological reason is that predation compensates for natural mortality; that is, increased predation reduces natural mortality, indicating that the net loss due to predation actually may be quite small. When predation reduces livestock density, the feeding conditions of the animals will improve, resulting in increased livestock weight and higher per animal slaughter value. At the same time, a smaller stock reduces the operating costs of the herders. 相似文献
158.
Andrew O. Hughes Jon M. Olley Jacky C. Croke Ian T. Webster 《Journal of environmental radioactivity》2009,100(10):858-865
Fallout 137Cs has been widely used to determine floodplain sedimentation rates in temperate environments, particularly in the northern hemisphere. Its application in low fallout, tropical environments in the southern hemisphere has been limited. In this study we assess the utility of 137Cs for determining rates of floodplain sedimentation in a dry-tropical catchment in central Queensland, Australia. Floodplain and reference site cores were analysed in two centimetre increments, depth profiles were produced and total 137Cs inventories calculated from the detailed profile data. Information on the rates of 137Cs migration through local soils was obtained from the reference site soil cores. This data was used in an advection–diffusion model to account of 137Cs mobility in floodplain sediment cores. This allowed sedimentation rates to be determined without the first year of detection for 137Cs being known and without having to assume that 137Cs remains immobile following deposition. Caesium-137 depth profiles in this environment are demonstrated to be an effective way of determining floodplain sedimentation rates. The total 137Cs inventory approach was found to be less successful, with only one of the three sites analysed being in unequivocal agreement with the depth profile results. The input of sediment from catchment sources that have little, or no, 137Cs attached results in true depositional sites having total inventories that are not significantly different from those of undisturbed reference sites. 相似文献
159.
Assessing Watershed-Scale, Long-Term Hydrologic Impacts of Land-Use Change Using a GIS-NPS Model 总被引:25,自引:0,他引:25
Land-use change, dominated by an increase in urban/impervious areas, has a significant impact on water resources. This includes
impacts on nonpoint source (NPS) pollution, which is the leading cause of degraded water quality in the United States. Traditional
hydrologic models focus on estimating peak discharges and NPS pollution from high-magnitude, episodic storms and successfully
address short-term, local-scale surface water management issues. However, runoff from small, low-frequency storms dominates
long-term hydrologic impacts, and existing hydrologic models are usually of limited use in assessing the long-term impacts
of land-use change. A long-term hydrologic impact assessment (L-THIA) model has been developed using the curve number (CN)
method. Long-term climatic records are used in combination with soils and land-use information to calculate average annual
runoff and NPS pollution at a watershed scale. The model is linked to a geographic information system (GIS) for convenient
generation and management of model input and output data, and advanced visualization of model results.
The L-THIA/NPS GIS model was applied to the Little Eagle Creek (LEC) watershed near Indianapolis, Indiana, USA. Historical
land-use scenarios for 1973, 1984, and 1991 were analyzed to track land-use change in the watershed and to assess impacts
on annual average runoff and NPS pollution from the watershed and its five subbasins. For the entire watershed between 1973
and 1991, an 18% increase in urban or impervious areas resulted in an estimated 80% increase in annual average runoff volume
and estimated increases of more than 50% in annual average loads for lead, copper, and zinc. Estimated nutrient (nitrogen
and phosphorus) loads decreased by 15% mainly because of loss of agricultural areas. The L-THIA/NPS GIS model is a powerful
tool for identifying environmentally sensitive areas in terms of NPS pollution potential and for evaluating alternative land
use scenarios for NPS pollution management. 相似文献
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