Study On The Distribution Of Heavy Metals And PAHs In The Multi-phases In The Nanhu Lake

Heavy metals (HM) and polycyclic aromatic hydrocarbons(PAHs) are two major pollutants, which were detected simultaneouslyin the environmental water. There are kinds of interactions betweenthem, such as: synergy, addition, and antagonism. Researchers havestudied the two pollutants individually. The researches on heavymetals include: (1) the gross of heavy metals in the sediment, whichindicates the input elements both by human activities and naturalfactors, and reflects the of environmental pollution degree.Consequently, it is very meaningful to study the gross of heavymetals for environment monitor and assessment. (2) The toxicityassessment of heavy metals. If bioavailable and toxicity effects wereconsidered, not all species of heavy metals are harmful to aquaticorganisms. Therefore, bioavailable effect was used to assess waterquality instead of the gross of heavy metals. Bioavailable effectscontain toxicity recognition, toxicity index, and toxicity assay. Thekey issue is the assay of heavy metals. (3) It is a hot issue ofresearching on the transformation of heavy metals in the multi-phasesof water environment. The heavy metals enter into the body of water,the heavy metals which were adsorbed on the suspended particulatestransfer from liquid phases to solid phases due to the physical-chemical and biology actions. So, there is less metal in the liquidphases. Generally, the concentration of heavy metal in the suspendedparticulates is several times higher than that in the sediment, andseveral hundred times of the dissolved heavy metal in the water. (4)Hydrobiology has an important effect on the heavy metalsenrichment and transformation. At present, there are quite moreresearches on the gross of heavy metal and biology restore the heavymetal in the sediment.Heavy metals and PAHs are often present together, the studieson PAHs content: Survey on PAHs contamination and sources ofPAHs. Survey on PAHs could make clear the kinds and contents ofPAHs in the environment. It is the foundation of study the relationbetween PAHs and the environmental medium. Meanwhile it is theprerequisite of all kinds of territory and globe politics. The possiblesource of PAHs could be traced by analyzing the ratio between PAHsmonomers. The ratio is determined by the difference PAHs source.The difference between the PAHs and heavy metals is the PAHscould be degraded while it is entering the environment. Thedegradation of the PAHs is concentrated on the microorganism andthe photodegradation. As one source of carbon, PAHs could bedegraded in the metabolism by microorganism. The PAHs adsorptionon the suspended particulates, sediment and surface coatings is animportant process for the transference, transform and returning.Hence, the PAHs distribution in the space is explored by analyzing itsconcentrations in the different phases.The thesis is about space distribution of the heavy metals suchas Cu, Zn, Pb, Cd and PAHs such as fluorene, phenanthrene,anthracene, pyrene in the multi-phases. It was found that heavymetals and PAHs have the similar distribution pattern in the Nanhulake multi-phases. The enrichment capacities of the sediment, surfacecoatings, and suspended particulates to heavy metals and PAHs inwere all in the tendency of increasing. Among of those theenrichment capacities of suspended particulates and surface coatingswere higher than that of sediment. It indicated that compared withsediment, those two gave an important effect on the transference andtransformation of heavy metals and PAHs in the water environment.The concentration of Cd was lowest in the threes phases, but theenrichment parameters were the highest due to the extremely lowconcentration of Cd in the water. That showed the sediment, surfacecoatings and suspended particulates were the convergence of traceheavy metals. The enrichment parameters of Zn were taken thesecond place, and the enrichment capacities of Pb and Cu weresimilar, but much lower than Cd and Zn. For the monomers of PAHs,the enrichment capacities of sediment, surface coatings andsuspended particulates to low molecular weight PAHs were higherthan that to high molecular weight PAHs.Then the correlation analysis between the metals, PAHs, Fe andMn oxides, and TOC have been studied by SPSS statistical analysis,and results indicated that the trends of correlation between the metalsof the sediments, suspended particulates and surface coatings weredifferent from each other. The correlation between Cu and Zn insuspended particulates was good, but not high in surface coatings andsediment. And also the correlations between Cu and Cd, Cu and Pb,and Pb and Cd achieved significant level, but not correlated insuspended particulates and surface coatings. The correlation analysisbetween Cd, Pb content and Fe, Mn oxides indicated that thecorrelated parameters of Cd and Fe in the three solid phases weregreater than those of Cd and Mn whatever positive correlation ornegative correlation, therefore, it could be concluded that Fe oxidesdefinitely make significant contributes to the adsorption of Cd onsediment, surface coatings, and suspended particulates. But Pb isextremely different from Cd, the correlated parameters of Pb and Fein the three solid phases were less than those of Pb and Mn, whichshowed that Mn oxides definitely make significant contributes to theadsorption of Pb on sediment, surface coatings, and suspendedparticulates. In addition, Cu and Fe, Mn was positively correlated insediment and suspended particulates, and the correlation with Fe wasgreater than with Mn. But Cu content in surface coatings with Fe, Mnwas negative correlated, and the correlation parameter with Fe wasless than with Mn. For Zn, there was no rule between it and Fe, Mn.PAHs in different phases have weak correlation in a certainsampling site. The monomers of PAHs in sediments have significantcorrelation, but the correlation was insignificant in surface coatingsand suspended particulates, indeed some monomers were negativecorrelation. Especially C13H10, the correlations of it with othermonomers were negative in the water phase, but positive correlatedin surface coatings and suspended particulates. Water phase,suspended particulates and surface coatings are influenced stronglyby environment, and the adsorption capacity of PAHs could beaffected by the physical-chemical characters and sunlight imposing tothe surface water, so the correlation difference will occur. But thesediment in the deep water was slightly influenced by the abovefactors. The correlation between monomers was preferable whichindicated the monomers have the same origin. The correlationcoefficiency between Fe oxides in the surface coatings and themonomers of PAHs is similar with that of Mn oxides, and both ofthem have negative correlation. The correlation coefficiency betweenFe oxides in suspended particulates and the monomers of PAHs isclosed to that of Mn oxides, both have positive correlation. Theresults were related with the similar geochemical properties of Fe andMn. TOC in suspended particulates has negative correlation with themonomers of PAHs, but in other phases it has positive correlationwith PAHs, especially in sediment there was significant correlationbetween them, which concluded organic matter has an importanteffect on the PAHs transference and transformation.In this paper, the distribution of heavy metals in organisms wasalso studied. The conclusion was the distribution of heavy metals inorganisms has the obvious rule. Among all of those the enrichmentcapacities of locus root and fish branchia to Cd and Pb were thestrongest, and after being adsorbed, heavy metals exist in locus rootand fish branchia. Each parts of locus and fish has the sameenrichment capacities to Cu, but the enrichment capacity of locus leafwas the strongest, and the enrichment capacities of fish branchia andbelly were slightly stronger than that of fish. The transference andtransformation of heavy metals in organisms are different. Nutrimentshave strong transference ability in organisms, which made theconcentrations of nutriment in every part were equivalent.Non-nutrient elements have relatively weak transference ability, afterbeing adsorbed, most of them were enriched in the root and branchia,which make the concentration in other parts were obviously less thanthat in the root and branchia.