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Cyanobacterial blooms are global phenomena that can occur in calm and nutrient-rich(eutrophic) fresh and marine waters. Human exposure to cyanobacteria and their biologically active products is possible during water sports and various water activities, or by ingestion of contaminated water. Although the vast majority of harmful cyanobacterial products are confined to the interior of the cells, these are eventually released into the surrounding water following natural or artificially induced cell death. Electrochemical oxidation has been used here to damage cyanobacteria to halt their proliferation, and for microcystin degradation under in-vitro conditions. Partially spent Jaworski growth medium with no addition of supporting electrolytes was used. Electrochemical treatment resulted in the cyanobacterial loss of cell-buoyancy regulation, cell proliferation arrest, and eventual cell death. Microcystin degradation was studied separately in two basic modes of treatment: batch-wise flow, and constant flow, for electrolytic-cell exposure. Batch-wise exposure simulates treatment under environmental conditions, while constant flow is more appropriate for the study of boron-doped diamond electrode efficacy under laboratory conditions. The effectiveness of microcystin degradation was established using high-performance liquid chromatography–photodiode array detector analysis, while the biological activities of the products were estimated using a colorimetric protein phosphatase-1 inhibition assay. The results indicate potential for the application of electro-oxidation methods for the control of bloom events by taking advantage of specific intrinsic ecological characteristics of bloom-forming cyanobacteria. The applicability of the use of boron-doped diamond electrodes in remediation of water exposed to cyanobacteria bloom events is discussed. 相似文献
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Organic acids released from plant roots can form complexes with cadmium (Cd) in the soil solution and influence metal bioavailability not only due to the nature and concentration of the complexes but also due to their lability. The lability of a complex influences its ability to buffer changes in the concentration of free ions (Cd); it depends on the association (, m mol s) and dissociation (, s) rate constants. A resin exchange method was used to estimate and (m mol s), which is the conditional estimate of depending on the calcium (Ca) concentration in solution. The constants were estimated for oxalate, citrate, and malate, three low-molecular-weight organic acids commonly exuded by plant roots and expected to strongly influence Cd uptake by plants. For all three organic acids, the and estimates were around 2.5 10 m mol s and 1.3 × 10 s, respectively. Based on the literature, these values indicate that the Cd- low-molecular-weight organic acids complexes formed between Cd and low-molecular-weight organic acids may be less labile than complexes formed with soil soluble organic matter but more labile than those formed with aminopolycarboxylic chelates. 相似文献
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Peter Michael Link Uwe A. Schneider Richard S. J. Tol 《Environmental Modeling and Assessment》2011,16(4):413-429
Using a bioeconomic model of the cod (Gadus morhua) and capelin (Mallotus villosus) fisheries of the Barents Sea, this study assesses the role of the fishermen’s behavior in reducing or intensifying the effects
on the stocks caused by altered population dynamics. The analysis focuses on the economic development of the fisheries employing
a coupled stock size–hydrography-based fishing strategy, which attempts to maximize returns from fishing over a given number
of fishing periods. Results show that if the fishing strategy is based on a short optimization period of only two fishing
periods, changes in population dynamics have a direct influence on the returns from fishing due to the strong pressure on
the stocks applied by the fisheries. If the strategy is based on a longer optimization period, fishing activities may be deferred
to allow for stock regrowth, which improves the economic performance of the fisheries. However, in that case, the relationship
between population dynamics and fishing activities becomes less clear, as even a reduction of the carrying capacities of the
two species allows for an increase in the amount of fish landed without causing a stock collapse due to an increased efficiency
of fleet utilization. The simulations indicate that management considerations and the time horizon of the fishing strategy
dominate the influence of altered population dynamics on the development of the stocks considered in the model. 相似文献
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Manuel Soler Cristina Ruiz-Castellano María del Carmen Fernández-Pinos Anja Rösler Juan Ontanilla Tomás Pérez-Contreras 《Behavioral ecology and sociobiology》2011,65(10):1997-2005
Most host species of obligate interspecific brood parasites are under strong selection because such parasitism, e.g., that
involving evictor nestmates, is highly costly. Egg rejection is one of the most efficient host defences against avian brood
parasites. Many hosts have thus evolved egg-recognition ability and rejection behaviour. However, this defensive mechanism
has not evolved in most species where only intraspecific brood parasitism occurs, probably because (1) the eggs of conspecific
females are very similar in appearance, making egg rejection less likely to emerge, and (2) such parasitism is frequently
less costly than interspecific parasitism. Using a captive population of house sparrows (Passer domesticus) with a low breeding density, we here provide new evidence showing that this species actually has a fine capacity to discriminate
conspecific eggs and to eject them (44.2% of foreign eggs ejected) while incurring very low rejection costs (4.2% of own eggs
ejected). This result contradicts those previously found in high-density house sparrow populations in which very high rejection
costs and very high clutch desertion rates were reported, probably as a consequence of intraspecific competition and infanticide
provoked by the high breeding density. The house sparrow has only rarely been reported as the host of an interspecific brood
parasite, which implies that it is a newly described example of an altricial species in which egg ejection has evolved and
is maintained in response to intraspecific brood parasitism. 相似文献
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