Response Of Macroalgae To Pyrene Toxicity And Its Pyrene Phytoremediation Mechanisms Under Eutrophication

The pollution of coastal waters is intensifying,and the phenomena of red tide,green tide and so on occurs frequently.It is seriously damaging the local ecological environment.Nutrients,heavy metal and polycyclic aromatic hydrocarbons(PAHs),as marine chemical pollutants which were closely relate to marine organism proliferation,their effects on waterbody are almost simultaneous.In order to investigate effects of multiple pollution on algae generation,Ulva prolifer a and U.linza were studied to reveal effects of NP enrichment on their growth and photosynthesis,and interation of pyrene and NP nutrients on their growth,photosynthesis,pollutant enrichment and pyrene distribution at subcellular levels.Main results were showed as follows:(1)Under unchanged P concentration(P3,30 μmol·L-1 P)and N application increased,Relative growth rate(RGR)of both Ulva were gradually increased,and at the N3(500μmol·L-1 N)level,RGR in both Ulva had reached the peak values.However,under unchanged N concentration(N3,500 μmol·L-1 N)and P application increased,RGR in U.prolifer a was increased,and reached the peak value at the P3,but RGR in U.linza was unaffected.The change trend of chlorophyll fluorescence parameters was found very similar to RGR.Under unchanged P concentration and N application increased,N accumulation in both Ulva were significantly increased,however,P concentration in both Ulva were significantly decreased.Under unchanged N concentration and P application increased,P accumulation in both Ulva were significantly increased.(2)RGR in U.prolifera and U.linza were decreased as the pyrene increased;moreover,RGR decrease in U.prolifer a was less significantly that in U.linza with NP application.This experiment also found at the different treatment of pyrene,NP enrichment made more increase in RGR of U.linza than that of U.prolifera.Under NP application increased fluorescence parameters in both Ulva under pyrene stresses,especially in U.linza and under high pyrene stress.NP enrichment was increased in both Ulva applied with NP,and pyrene stress decresed their N enrichment.(3)Pyrene adsorption in subcellular groups of U.prolifer a and U.linza appeared an increase trend as the pyrene increased,while these pyrene adsorption were decreased under NP application.The distribution of subcellular fractions showed the more propertion of pyrene was existed in the mitochondria,followed by chloroplasts,nuclei,cell wall and soluble part.Moreover,the allocation of pyrene in mitochondria,chloroplasts and soluble fractions of U.linza was significantly higher than that of U.prolifera.In conclusion,compared with P,N concentration change has more influence on growth and photosynthesis of both Ulva.And 500 μmol·L-1 N,30 μmol·L-1 P and N/P:16.67 were the optimal condition for the growth of both Ulva in this study.It also suggested that the algae enriched nutrition has continued to rise under the increasing eutrophication condition;U.prolifera has a better adaptation to pyrene toxicity than U.linza,which was due mainly to higher nutrient content,and stronger photosynthesis maintained in U.prolifera.NP application improved their pyrene resistance,and the improvement was found to be pronounced in U.linza than U.prolifera,which was due mainly to higher nutrient content,and stronger photosynthesis induced by NP application in U.linza under pyrene stress.NP application reduced pyrene adsorption in U.prolifera,but did not change it in U.linza.However,pyrene adsorption in U.prolifera was more markedly than that in U.linza;Moreover,the allocation of pyrene in mitochondria,chloroplasts and soluble fractions of U.linza was significantly higher than that of U.prolifera,which was probably one of the important reasons of more sensitivity to pyrene toxicity of U.linza.