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dc.contributor.supervisorBROWN, MURRAY
dc.contributor.authorMOHAMMED, DANA
dc.contributor.otherSchool of Biological and Marine Sciencesen_US
dc.date.accessioned2017-05-19T12:40:10Z
dc.date.issued2017
dc.date.issued2017
dc.identifier10316510en_US
dc.identifier.urihttp://hdl.handle.net/10026.1/9285
dc.description.abstract

Accumulation and toxicity of cadmium, lead and thallium in duckweed (Lemna minor L.) The toxicity and accumulation of lead, cadmium and thallium in the aquatic plant Lemna minor was investigated, using a modification of the Organisation for Economic Co-operation and Development (OECD) standard growth inhibition test. Plants were cultured in modified Swedish Institute Standard (SIS) at pH 6.5±0.5 under 85 µmol m-2 S-1 at 25°C and exposed to a wide range of lead, cadmium, and thallium concentrations from environmentally realistic to very high concentrations (0.001, 0.01,0.1, 1, 10, 100, 1000 and 10 000 µmol L-1) for seven days. Various physico-biochemical endpoints were measured after seven days of exposure. The concentrations of dissolved lead, cadmium, and thallium remaining in the residual solutions, and accumulation of lead, cadmium and thallium in fronds and roots were assessed using Inductively Couple Plasma – Mass Spectroscopy (ICP-MS). Over the exposure duration, lead, cadmium, and thallium concentrations in solution decreased rapidly and chlorosis was observed in fronds exposed to the three highest lead, cadmium, and thallium concentrations. After seven days of exposure, there were significant decreases in the relative growth rate (RGR), relative frond area (RFA), pigment content (chlorophyll a, b and total carotenoid) and activity of photosystem II (Fv/Fm) at concentrations of 0.1, 1, 10, 100, 1000 and 10 000 µmol L-1Pb, 10, 100, 1000 and 10 000 µmol L-1cd, 0.01,0.1, 1, 10, 100, 1000 and 10 000 µmol L-1TI. However, our results suggested that root elongation based on relative growth rate of L. minor will be an optimal and relevant endpoint in compare to other endpoints. As expected, results demonstrated that root elongation was concluded that root length was most predictive of a dose response model compared to the rest of growth endpoints and physiological and biochemical endpoints when assessing toxicity of lead, cadmium and thallium using L. minor. Toxicity testing for the floating macrophytes should include root elongation measurement which alone will be sufficient to meet sensitivity and variability requirements for toxicity testing. Cellular concentrations of lead, cadmium, and thallium were higher in roots than fronds, whereas more lead, cadmium, and thallium was adsorbed to the extracellular matrix of fronds than roots. The bio - concentration factor (BCF; i.e. lead concentration in plant tissue at day seven relative to residual lead concentration in the growth medium at day seven) indicates that L. minor is a good accumulator of lead, cadmium, and thallium particularly at lower concentration, but the physiological data shows that these metals toxic at concentrations that can be encountered in wastewater treatment facilities. The translocation factor (TF) value was found to be less than 1. Though, lead, cadmium and Thallium was mostly stored in roots, only minor amounts of lead, cadmium and thallium were trans located to fronds.

en_US
dc.description.sponsorshipKURDISTAN REGIONAL GOVERNMENTen_US
dc.language.isoen
dc.publisherUniversity of Plymouth
dc.rightsAttribution-ShareAlike 3.0 United States*
dc.rights.urihttp://creativecommons.org/licenses/by-sa/3.0/us/*
dc.subjectLemna Minor
dc.subjectHeavy Metals
dc.subjectLead
dc.subjectCadmium
dc.subjectThallium
dc.subjectAccumulation
dc.subjectAquatic Plantsen_US
dc.subject.classificationMPhilen_US
dc.titleACCUMULATION AND TOXICITY OF CADMIUM, LEAD AND THALLIUM IN DUCKWEED (LEMNA MINOR L.)en_US
dc.typeThesis
plymouth.versionpublishableen_US
dc.identifier.doihttp://dx.doi.org/10.24382/1233
dc.rights.embargodate2018-05-19T12:40:10Z
dc.rights.embargoperiod12 monthsen_US
dc.type.qualificationMastersen_US
rioxxterms.funderUniversity of Sulaimanien_US
rioxxterms.identifier.projectHUMAN DEVELOPMENT CAPACITY PROGRAM (HCDP)en_US
rioxxterms.versionNA


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