【正文】 Cd, Cr, Pb, and As, they have been taken the most important heavy pollutants in the environment, also Zn, Cu, Co, Ni，Se and some other pollutant were regarded very toxic. Heavy metals like Zn, Fe, Cu, Mn are essential for plant growth and important constituents of many enzymes of metabolic importance. Other metals like Pb, Cd, As, Se, Cr and Al are biologically nonessential and toxic above certain threshold levels. It is found in the environment in three major states: chromium (0), chromium (III), and chromium (VI). Chromium (III) occurs naturally in the environment, while chromium (VI) and chromium (0) are generally produced by industrial processes. Cr (III) showed no toxicity effect to plant, but Cr (VI) has very serious toxicity to plant. Excess Cd causes a number of toxic symptoms in plants ., growth retardation, inhibition of photosynthesis. It forms a number of salts, of which the sulfate is most mon。6. 在鉻和鈷復合處理時，低濃度表現(xiàn)為拮抗作用，較高濃度時，表現(xiàn)為協(xié)同作用。在所有重金屬對蘿卜種子的毒性測試下，根和莖比萌發(fā)率更準確、敏感。通過實驗，得到如下結論：1. 在重金屬鎘、鉛單獨處理時，所有蘿卜種子的萌發(fā)率和幼苗生長均受到明顯的抑制。根和幼芽中重金屬含量的測定也在7天后，重金屬含量的測定用火焰原子吸收測定儀測定。用滴管吸取乙醇，將濾紙上的葉綠體色素全部洗入容量瓶中，直至濾紙和殘渣中無綠色為止。1℃，光周期為12小時。本次實驗首先篩選飽滿、大小均勻的蘿卜種子用做實驗種子，用流水清洗培養(yǎng)皿3次，再用蒸餾水沖洗，烘干。實驗中所用的重金屬鹽及濃度如下： CdCl2如今，隨著工業(yè)化、城市化的發(fā)展，污染物包括重金屬進入環(huán)境的數(shù)量越來越多，各種疾病的突發(fā)率都與水果和蔬菜的食用緊密相關。本實驗對蘿卜種子在重金屬污染環(huán)境中的萌發(fā)、早期生長、葉綠素含量、重金屬累積等生理生化指標進行了初步研究。重金屬還可通過農(nóng)肥，下水道污泥，市政廢棄物以及殺蟲劑等進入土壤，重金屬一旦進入土壤它的總量就很難減少。總之，重金屬毒性的大小往往是由其從在的形態(tài)所決定，毒性大的形態(tài)將被有機體的組織器官吸收后，或對神經(jīng)系統(tǒng)造成嚴重的影響，或造成生理上的迫害甚至死亡。當然，重金屬的生物毒性是與其存在的形態(tài)是密不可分的，比如就汞、鉛、砷、鎘來說，當它們以陽離子形態(tài)存在時毒性會增加。早在20世紀60年代，污水灌溉就成為農(nóng)業(yè)灌溉的重要部分，特別是在中國的北方。首先，一些土壤本身就含有大量重金屬，不同的土壤類型包含的重金屬的量不同，人類活動可以使得土壤中固有的這些重金屬轉移到空氣中、水中和其它土壤中，造成重金屬污染。鉛的可溶性和不溶性的形態(tài)對于植物都具有毒性作用。另外一些重金屬對植物以及生長具有更大的毒性作用，包括砷、鈷、鋁、硒等。造成汞對蘿卜根生長和莖生長的抑制能力遠遠大于對蘿卜種子萌發(fā)的抑制力的原因可能是由于汞在蘿卜的根和莖中的積累到一定量時造成抑制性最大。同時，對于生物來說，汞既不是植物細胞生長所必須元素，也不會產(chǎn)生一般積極的生態(tài)作用。三價鉻對植物及其生長一般表現(xiàn)出很少的毒性，但是六價鉻對植物及其生長大都表現(xiàn)出有很大的毒性效應。由于汞、鎘、鉻、 鉛、砷的強毒性使得它們在土壤重金屬污染中占有非常重要的地位，除此之外，鋅、銅、 鈷、鎳、硒和一些其它元素也因其對生物的毒性而特別被關注。隨著經(jīng)濟發(fā)展以及由此帶來的生態(tài)結構破壞，自然災害的增加，可利用的土壤已經(jīng)越來越少。全世界大部分范圍內(nèi)的土壤都在不同的程度上受到重金屬的污染。碩 士 學 位 論 文重金屬污染對蘿卜的生態(tài)毒理效應研究Ecotoxicological effects of Heavy Metals on Raphanus Sativus摘 要隨著全球經(jīng)濟的發(fā)展，重金屬通過各種方式進入土壤中，從而使得土壤的重金屬污染越來越嚴重。 從全球范圍來看，重金屬污染被認為是最主要的環(huán)境污染之一。相比北方，中國南部大部分地區(qū)重金屬污染較輕，但是在福州、寧波、上海、武漢、成都和一些地區(qū)重金屬污染日益嚴重且造成了各種各樣的生態(tài)問題。，但由于其毒性和其它性質與重金屬相似，所以砷和硒也被認為是重金屬污染物。其中以三價鉻最多，而六價鉻和單質鉻主要來自工業(yè)生產(chǎn)當中。汞是毒性很大的污染物。然而，不同重金屬對植物種子萌發(fā)和幼苗早期生長抑制的影響機理是不同的。這些重金屬元素的過量存在都會導致植物種子萌發(fā)和早期幼苗生長受的影響。雖然鉛對于植物來說不是必須的元素，但當其達到一定的量時將會對植物生長起到抑制作用，從而影響植物的光合作用、細胞分裂和植物對水分的吸收。土壤中的重金屬污染源有很多。污水灌溉也是重金屬污染的主要來源之一。除此之外，廢棄物中也包括很多的重金屬元素，不同重金屬的混合使得不同廢棄物對生物有著不同的毒害作用。大多數(shù)情況下，由于這些重金屬陽離子對巰基具有很強的親合力，從而對有機體中正常的酶活動造成很大的破壞，最后將改變酶物質的活性，產(chǎn)生致命性的副作用。在污染環(huán)境下生長的植物將含有重金屬以及其他污染物，這必將影響到人們的健康生活水平。在本實驗中，其中一些重金屬（鉛、鎘）在低濃度時對某些種子的萌發(fā)有促進作用，但是大多重金屬在超過一定的濃度范圍后都會對蘿卜的種子萌發(fā)產(chǎn)生抑制作用。這就說明蘿卜對重金屬污染有一定的忍耐性，如果已受重金屬污染的蘿卜被當做食物食用勢必會對人體造成很大危害。作為基礎的相關研究，本實驗通過Hg、Pb、Cd、Co、Cr對大部分萌發(fā)種子的抑制的研究來說明重金屬對種子萌發(fā)與生長的毒害效應。本實驗所用蘿卜種子由甘肅省農(nóng)科院提供。1℃，晚上溫度為2025177。然后取濾紙1張，置漏斗中，用乙醇濕潤，沿玻璃棒把提取液倒入漏斗中，過濾到25 mL棕色容量瓶中，用少量乙醇沖洗研缽、研棒及殘渣數(shù)次，最后連同殘渣一起倒入漏斗中。以95%乙醇為空白，在波長665nm、649nm和470nm下測定吸光度。冷卻后用蒸餾水稀釋定容至25ｍＬ,最后用原子吸收分光光度計測定重金屬含量；試驗數(shù)據(jù)源于每組濃度六次重復的平均值，數(shù)據(jù)分析應用SPSS ()軟件，對數(shù)據(jù)進行單因素方差分析（oneway analysis of variance (ANOVA)）和多重比較（least significant difference (LSD)）。 3. 蘿卜種子在受所有不同濃度的重金屬處理下，其根長均受到了抑制，且抑制顯著。5. 重金屬在蘿卜體內(nèi)的累積與重金屬濃度呈正相關，且重金屬更容易累積在蘿卜的根部，不易遷移至莖部。但在兩種重金屬低濃度污染對根和莖的生長表現(xiàn)為拮抗作用。 the aim of the study was to pare the effect of Zn2+ to seed germination, root and plumue growth of radish. Lead is not essential for plants, and excessive amounts can cause growth inhibition, as well as reduced photosynthesis, mitosis, and water lead and dissoluble lead are poisonous, Pb can be entered the environment by mine, melting, pesticide, transportation, coal and industry related to Pb, Pb was regarded as no positive bioeffect, many experiment and analysis have proved that Pb can enter the tissue of plant through root and shoot, and then enriched in plant, and the enrich degree pared to it’s habitat. The source of heavy metal pollutant in soil have many approaches, firstly, some soil itself contain heavy metal inbeing, different soil type contain different heavy metal pollutant, in another, because of human’s activity, heavy metal pollution were spread out to the air, water and at trace levels heavy metals are natural ponents of soils, activities such as mining, industry, and localized intensive agriculture have contributed to undesirable accumulations of toxic metals in many areas around the world. Furthermore, heavy metal pollution has increased with the population density。 (, , , , mg/l), K2Cr2O7 (, , , , mg/l), CoCl21℃ day/night temperature. The germination rate was recorded at different time, after germination, the root and shoot length were measured the sprout up to half of the seed length was regarded as germinated, according to the different seed and different heavy metals, the note time of different test were different too, at the end of the test, the root and shoot length of every seed were measured using Digital Caliper. All the data of the thesis were means of six replicated.The chlorophyll and the carotenoid content of plant were determined 7 days after the addition of the test solutions. Fresh leaves ( g) were homogenized using a pestle and mortar in to 95% ethanol or 80% acetone with a small amount of quartz sand and the powder of calcium carbonate. Plus 4 mL 95% ethanol again and continue homogenize, then put down whisht for 3 to 5 minutes. The homogenate was filtered through ashless filter paper and made up to 10mL with 95% ethanol. The filtered solution was used for chlorophyll and carotenoid estimation. Absorbance of the solution was measured at 665, 649 and 470 nm using a UV/vis spectrophotometer. Seven days after exposure to metals, the plants were washed three times in distilled water and divided into the cotyledons and roots. The heavy metals were determined by the atomic absorption spectrometry with the flame. All samples were dried separately for 24 h at 80 176。 Root。 Metal accumulation