The Ecotoxicological Effects Of Anthracene And Benzopyrene Alone And In Combination On The Leaves

With the progress of the society and the development of the modern industry,people’s living standards continue to improve, but the environmental pollution is becoming more and more serious,at the same time people’s attention are drawn to the water pollution.Our country’s water distribution is uneven, and freshwater amount accounted for less than one percent of the total water resources. Untreated or substandard industrial wastewater were directly discharged into rivers, which contains a lot of poisonous and harmful substances,and it will polluted water directly, make the sharp decline in water quality, aquatic life threatened, threatening human health.Sewage emissions are also increasing, which contains a lot of organic compounds that can also cause pollution to water, and ends up with eutrophication. PAHs(polycyclic aromatic hydrocarbons) is common organic pollutants in water environment, and the industrial wastewater contains a large number of PAHs, until now more than 200 kinds of PAHs has been found, a significant proportion of PAHs has strong carcinogenic and respectively, the strongest toxicity is benzopyrene and anthracene.Anthracene and benzopyrene as many PAHs’ s matrix, the studing of sole and the combination of the two PAHs’ s toxic effects of fresh water plant can provide powerful evidence to other PAHs ecological toxicology effects on the freshwater creatures.Three leaves duckweed(Lemna minor), which also called duckweed is a common float plant in the fresh water, it has the absolute advantage growing in the fresh water to other plants with its leaves floating on the water and rooting deep into the water to absorb nutrients leads to fast growth and high reproduction rate. As primary producers of freshwater ecosystems, L. minor using the water nutrients as carbon source, store energy through photosynthesis, and through biological enrichment can affect other freshwater creatures.As we all know it plays a vital role in purifying water quality.The study based on the duckweed as the subjects in this paper, through ecological toxicology experiment, studies the PAHs- Anthracene and benzopyrene separate and joint action of duckweed ranking from total group to individual cells and then to the molecular level of toxic effects, some valuable results are obtained:1. Effect of anthracene on physiological and biochemical characteristics of L. minor.(1) Anthracene have inhibition to the growth of duckweed and presented the obvious dose effect relationship. The duckweed’s relative growth rate falling along with the rising of the concentrations of anthracene.(2) With the increaseing of concentration of anthracene, chlorophyll content showed a trend of lower after the first rise; Malondialdehyde(MDA) content showed a trend of rising; Peroxidase(POD) activity presented lowing after the first increasing.2. Effect of benzopyrene on physiological and biochemical characteristics of L. minor.(1) Benzopyrene have inhibition to the growth of duckweed, but when the concentration of benzopyrene below 0.5mg/L, the growth presented promoting trendency of duckweed, when the concentration of benzopyrene above 0.5mg/L, the growth presented inhibition trendency of duckweed, and the relative growth rate falling.(2) With the increaseing of concentration of benzopyrene, content of chlorophyll presented lower trends; Malondialdehyde(MDA) content presented a trend of reducing after the first rising; Peroxidase(POD) activity without too big change, but presented a downward trend overall.3. Effect of the combination of anthracene and benzopyrene on physiological and biochemical characteristics of L. minor.(1) Under the joint action of anthracene and benzopyrene, the toxicity is intensified,the duckweed growth presents obvious inhibitory effect, and the effect is more serious than the single effect.The results show the synergy.(2) To fix benzopyrene concentration on 0.5mg/L, the duckweed’s relative growth rate falling along with the rising of the concentrations of anthracene; chlorophyll content showed a trend of decreasing; Malondialdehyde(MDA) content showed a trend of increasing, but not obvious; Peroxidase(POD) activity fell sharply.4. Effect of the combination of anthracene and benzopyrene on DNA damage of L.minor.(1) Under the acetone process, duckweed’s DNA electrophoresis diagram and the control group was not significantly difference.(2) The stripe gradually blurred on the Concentration of 0.5mg/L of benzopyrene combine with the concentration of 5mg/L and 20mg/L of anthracene compared to the control group, which presented DNA damaging degree aggravating gradually, and the content is lower.5. Effect of the combination of anthracene and benzopyrene on the submicrosopic structure of L.minor.(1) Under the acetone process, duckweed’s submicroscopic structure keep the normal state and presented no significant difference with the control group.(2) Under the influence of anthracene single, duckweed’s cells damaged gradually serious and submicroscopic structure changed along with the concentration increasing.(3) Under the joint action, the cell damage is more serious and internal structure disorder with the cell internal structure deformation and even appeared dissolve chloroplasts and the serious plasmolysis.