A new nonlinear predator-prey model with incomplete trophic transfer is introduced. In this model, we assume that the rate of the trophic absorption of the predator is less than the rate of the conversion of consumed ...A new nonlinear predator-prey model with incomplete trophic transfer is introduced. In this model, we assume that the rate of the trophic absorption of the predator is less than the rate of the conversion of consumed prey to predator in the Ivlev-type functional responses. The existence and uniqueness of the positive equilibrium of the model and the stability of the equilibrium of the model are studied under various conditions. Hopf bifurcation analysis of the delayed model is provided.展开更多
Barnacles have very high accumulated trace metal body concentrations that vary with local trace metal bioavailabilities and represent integrated measures of the supply of bioavailable metals. Pioneering work in Chines...Barnacles have very high accumulated trace metal body concentrations that vary with local trace metal bioavailabilities and represent integrated measures of the supply of bioavailable metals. Pioneering work in Chinese waters in Hong Kong highlighted the potential value of barnacles (particularly Balanus amphitrite) as trace metal biomonitors in coastal waters,identifying differences in local trace metal bioavailabilities over space and time. Work in Hong Kong has also shown that although barnacles have very high rates of trace metal uptake from solution, they also have very high trace metal assimilation efficiencies from the diet. High assimilation efficiencies coupled with high ingestion rates ensure that trophic uptake is by far the dominant trace metal uptake route in barnacles, as verified for cadmium and zinc. Kinetic modelling has shown that low efflux rate constants and high uptake rates from the diet combine to bring about accumulated trace metal concentrations in barnacles that are amongst the highest known in marine invertebrates.展开更多
The ubiquitous occurrence of plastic nano-and micro-particle contamination has raised concerns about its potential risks and impacts on the global environment,especially in aquatic ecosystems.Hundreds of aquatic speci...The ubiquitous occurrence of plastic nano-and micro-particle contamination has raised concerns about its potential risks and impacts on the global environment,especially in aquatic ecosystems.Hundreds of aquatic species,from different trophic levels,have been affected by this“new”contaminant,which has been reported mainly in their digestive tracts.Consequently,current knowledge about plastic nano-and micro-particle spread and the potential impact on aquatic biota is growing rapidly.However,there is a significant lack of understanding of the trophic spread of microplastic contamination and integration of knowledge derived from laboratory assays with that from field research is difficult.Field experiments are unable to deal with differentiating between directly and indirectly ingested plastic microparticles.On the other hand,laboratory assays evaluating the influence of plastic microparticles and of their adhered or constitutive toxins on representative species cannot satisfactorily simulate the real environment.As a result,little is known about the effective transfer of plastic particles through the trophic net and the resulting human health risks.The present review seeks to gather information that can give a more accurate idea of the current situation and future challenges to be faced in mitigating the environmental and human effects of plastic particle pollution in aquatic,particularly estuarine,ecosystems.展开更多
We studied the dynamics of mercury（Hg） transfer in Phaseolus vulgaris plants grown in soil with Hg-doped compost at the maximum levels permitted by Colombian law on organic amendments. Quantitative evaluation of tra...We studied the dynamics of mercury（Hg） transfer in Phaseolus vulgaris plants grown in soil with Hg-doped compost at the maximum levels permitted by Colombian law on organic amendments. Quantitative evaluation of transfer was made in different plant organs： roots,stem, leaves, pods and seeds. Matrix effect was determined in doped soil assays, using soil with and without addition of compost. Results showed that the use of organic matter reduced Hg transfer to the plant and the amount transferred was differentially distributed to the organs. We observed an inverse relationship between concentration and distance from the body to the root. It was evident that transfer was mediated by quantitative factors;the greater the presence of mercury in soil, the larger the amount that will be transferred.Results also indicate the remedial effect of compost and the presence of a barrier, at the root level, against mercury translocation to the plant aerial parts.展开更多
基金Supported by the Anhui Provincial Department of National Land and Resources with their Science and Technology Project entitled "Research on a Dynamic Monitoring Land Usage,Evaluation and Decision Support Management System in Wanjiang Demonstration Area"(Grant No.2011-K-23)Anhui Agricultural University,China(Grant No.YJ2012-03,No.XK2013029 and No.11201002)The Natural Sciences and Engineering Research Council of Canada
文摘A new nonlinear predator-prey model with incomplete trophic transfer is introduced. In this model, we assume that the rate of the trophic absorption of the predator is less than the rate of the conversion of consumed prey to predator in the Ivlev-type functional responses. The existence and uniqueness of the positive equilibrium of the model and the stability of the equilibrium of the model are studied under various conditions. Hopf bifurcation analysis of the delayed model is provided.
文摘Barnacles have very high accumulated trace metal body concentrations that vary with local trace metal bioavailabilities and represent integrated measures of the supply of bioavailable metals. Pioneering work in Chinese waters in Hong Kong highlighted the potential value of barnacles (particularly Balanus amphitrite) as trace metal biomonitors in coastal waters,identifying differences in local trace metal bioavailabilities over space and time. Work in Hong Kong has also shown that although barnacles have very high rates of trace metal uptake from solution, they also have very high trace metal assimilation efficiencies from the diet. High assimilation efficiencies coupled with high ingestion rates ensure that trophic uptake is by far the dominant trace metal uptake route in barnacles, as verified for cadmium and zinc. Kinetic modelling has shown that low efflux rate constants and high uptake rates from the diet combine to bring about accumulated trace metal concentrations in barnacles that are amongst the highest known in marine invertebrates.
文摘The ubiquitous occurrence of plastic nano-and micro-particle contamination has raised concerns about its potential risks and impacts on the global environment,especially in aquatic ecosystems.Hundreds of aquatic species,from different trophic levels,have been affected by this“new”contaminant,which has been reported mainly in their digestive tracts.Consequently,current knowledge about plastic nano-and micro-particle spread and the potential impact on aquatic biota is growing rapidly.However,there is a significant lack of understanding of the trophic spread of microplastic contamination and integration of knowledge derived from laboratory assays with that from field research is difficult.Field experiments are unable to deal with differentiating between directly and indirectly ingested plastic microparticles.On the other hand,laboratory assays evaluating the influence of plastic microparticles and of their adhered or constitutive toxins on representative species cannot satisfactorily simulate the real environment.As a result,little is known about the effective transfer of plastic particles through the trophic net and the resulting human health risks.The present review seeks to gather information that can give a more accurate idea of the current situation and future challenges to be faced in mitigating the environmental and human effects of plastic particle pollution in aquatic,particularly estuarine,ecosystems.
基金the University of Antioquia (UdeA ) for partially funding this research (grant CODI-10083-2007)the BIOORGANICOS S.A.Company for participating in the project and supplying organic substratesthe research group GAIA-UdeA for access to the mercury analyzer
文摘We studied the dynamics of mercury（Hg） transfer in Phaseolus vulgaris plants grown in soil with Hg-doped compost at the maximum levels permitted by Colombian law on organic amendments. Quantitative evaluation of transfer was made in different plant organs： roots,stem, leaves, pods and seeds. Matrix effect was determined in doped soil assays, using soil with and without addition of compost. Results showed that the use of organic matter reduced Hg transfer to the plant and the amount transferred was differentially distributed to the organs. We observed an inverse relationship between concentration and distance from the body to the root. It was evident that transfer was mediated by quantitative factors;the greater the presence of mercury in soil, the larger the amount that will be transferred.Results also indicate the remedial effect of compost and the presence of a barrier, at the root level, against mercury translocation to the plant aerial parts.
基金Project supported by the US Department of Agriculture-Agriculture and Food Research Initiative(USDA-AFRI)(No.2011-67006-30181)the USDA-AFRI Hatch Program(No.MAS 00978)
