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Enteromorpha prolifera (Scheldt Estuary) and E. linza (Thermaikos Gulf) were incubated at three salinities with 100 and 200microgL(-1)Cd and Zn. The objective was to measure effects of Cd, Zn and nitrogen (N) status on the pools of metal-binding non-protein thiols: glutathione and phytochelatins, (gamma-glutamyl-cysteinyl)(n)-glycine (PC). In E. linza, ammonium pools were higher, but amino acid pools, total N and protein contents were lower than in E. prolifera. Reduced glutathione (GSH) pools were positively correlated with free glutamate and protein contents. In E. linza GSH pools increased and the ratio of reduced to oxidized glutathione (GSH:(GSH+0.5GSSG)), an indicator of oxidative stress, decreased with Cd contents, indicating Cd-induced glutathione oxidation. Total glutathione pools (reduced plus oxidized) ranged from 16nmolSgdwt(-1) in controls (at 0.5micromolCdgdwt(-1)) to 179nmolSgdwt(-1) (at 1.9micromolCdgdwt(-1)) at the highest cadmium dosage. Cadmium stimulated PC synthesis in E. prolifera which suggests that in N-rich algae, glutathione pools were high enough for PC synthesis. In both species GSH and protein increased with Zn contents, whereas GSH:(GSH+0.5GSSG) decreased, which would indicate Zn-induced oxidative stress; in E. linza, at the highest salinity the glutathione redox ratio decreased from 0.61 (at 2.9micromolZngdwt(-1)) to 0.26 (at 4.9nmolSgdwt(-1)) (at 0.5molCdgdwt(-1)). PCs were not synthesized in response to Zn, which may have resulted in Zn-induced GSH oxidation. The presence of both oxidative effects (Cd, Zn) and detoxification (Cd) could be identified by observing the responses of glutathione and PC pools to metal stress. 相似文献
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This paper revisits models of coastal trapped waves and examines them with the inclusion of friction. In addition we use a numerical method which at least theoretically will have enhanced accuracy. The model has continuous stratification and variable depth. It is linear, quasigeostrophic and hydrostatic, and utilizes perturbation from this fundamental state. The model is applied with both idealized and realistic topography and stratification.Responsible Editior: Phil Dyke 相似文献
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The integrated hydrological modelling system, IHMS, has been described in detail in Part 1 of this paper. The system comprises three models: Distributed Catchment Scale Model (DiCaSM), MODFLOW (v96 and v2000) and SWI. The DiCaSM simulates different components of the unsaturated zone water balance, including groundwater recharge. The recharge output from DiCaSM is used as input to the saturated zone model MODFLOW, which subsequently calculates groundwater flows and head distributions. The main objectives of this paper are: (1) to show the way more accurate predictions of groundwater levels in two Cyprus catchments can be obtained using improved estimates of groundwater recharge from the catchment water balance, and (2) to demonstrate the interface utility that simulates communication between unsaturated and saturated zone models and allows the transmission of data between the two models at the required spatial and temporal scales. The linked models can be used to predict the impact of future climate change on surface and groundwater resources and to estimate the future water supply shortfall in the island up to 2050. The DiCaSM unsaturated zone model was successfully calibrated and validated against stream flows with reasonable values for goodness of fit as shown by the Nash‐Sutcliffe criterion. Groundwater recharge obtained from the successful tests was applied at various spatial and temporal scales to the Kouris and Akrotiri catchments in Cyprus. These recharge values produced good estimates of groundwater levels in both catchments. Once calibrated, the model was run using a number of possible future climate change scenarios. The results showed that by 2050, groundwater and surface water supplies would decrease by 35% and 24% for Kouris and 20% and 17% for Akrotiri, respectively. The gap between water supply and demand showed a linear increase with time. The results suggest that IHMS can be used as an effective tool for water authorities and decision makers to help balance demand and supply on the island. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
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