本文關(guān)鍵詞： 澎溪河 三峽庫區(qū) 沉積物重金屬 遷移轉(zhuǎn)化 藻類　出處：《重慶交通大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：重金屬污染一直是全世界關(guān)注的熱點,而河流中大量的重金屬排入對水環(huán)境造成了嚴(yán)重后果。重金屬污染是物無機有毒物質(zhì),其難以被降解,還會在生物體內(nèi)富集,對生物造成持久性影響。因此,研究水體重金屬污染特征并評價其對水體的影響程度具有重要意義。本文以澎溪河水體、未淹水沉積物和淹水沉積物為研究對象,測定了其中Fe、Mn、Cr、Pb、Cu、Cd六種重金屬的含量分布、形態(tài)特征;通過模擬實驗研究了水位漲落影響下沉積物重金屬的遷移轉(zhuǎn)化規(guī)律,以及沉積物中Cd的釋放對水體藻類生長情況的影響。研究取得的主要成果如下:①澎溪河枯水期水體中各重金屬含量普遍高于平水期和豐水期,且在平水期變化較穩(wěn)定,總體上重金屬含量大小順序為FeMnCuCrPbCd。六種重金屬元素中僅Pb和Cu在枯水期含量分別超過了國家II類水質(zhì)標(biāo)準(zhǔn)限值和I類水質(zhì)標(biāo)準(zhǔn)限值。②沉積物中重金屬含量大小順序為FeMnPbCuCrCd,其中Cu的變異系數(shù)最大,沿程變化最大,其受到人類活動影響比其它重金屬嚴(yán)重。六種重金屬中Cr、Pb、Cu主要以殘渣態(tài)形態(tài)存在,對環(huán)境危害較小。采用地積累指數(shù)法對河流沉積物重金屬污染情況的評價結(jié)果表明,沉積物受到Cd、Pb和Cu的污染。③水位漲落模擬實驗發(fā)現(xiàn),淹水時沉積物中重金屬含量大小順序為FeMnPbCrCuCd,污染程度大小順序依次為CdPbMnCuCrFe;水位退縮后出露的沉積物中重金屬含量大小順序為FeMnPbCrCuCd,污染程度大小順序依次為CdPbMnCuCrFe。研究表明,水位退縮后的沉積物中重金屬的含量有所降低,而不同元素的形態(tài)變化各異,Cr、Pb和Cu在淹水前后重金屬形態(tài)百分比順序保持不變。④沉積物中Cd釋放模擬實驗發(fā)現(xiàn),上覆水中N/P比平均大于100,呈較強富營養(yǎng)條件,磷成為影響藻類生長的限制因子;藻類總數(shù)和葉綠素a含量呈先減少后增加的趨勢。未進行遮光處理的樣本中藻類總數(shù)和葉綠素a整體呈下降趨勢,這與總磷、總氮濃度變化趨勢一致;而遮光樣本的藻類很難生長繁殖,因此其氮、磷含量一直呈增長趨勢。水體中重金屬Cd的含量和藻類總數(shù)、葉綠素a的相關(guān)分析表明,它們之間存在較弱相關(guān)性或者拮抗作用,水體中的Cd促進部分藻類生長。
[Abstract]:Heavy metal pollution has been the focus of attention all over the world, and the discharge of a large number of heavy metals in rivers has caused serious consequences to the water environment. Heavy metal pollution is inorganic toxic substance, which is difficult to be degraded. Therefore, it is important to study the characteristics of heavy metal pollution and evaluate its influence on the water body. The content distribution and morphological characteristics of six heavy metals in unflooded sediments and flooded sediments were determined. The migration and transformation of heavy metals in sediments under the influence of water level fluctuation were studied by simulation experiments. And the effect of CD release from sediment on algae growth in water body. The main results are as follows: 1. The heavy metal content in water during the dry period of Penghuihe River is generally higher than that in the normal and high water periods. And the change is stable in the mean water period. As a whole, the order of heavy metal content is FeMnCuCrPbCd.The contents of Pb and Cu of the six heavy metal elements in the dry season exceed the national water quality standard limit of class II and the water quality standard limit of class I, respectively. The order of heavy metal content in sediment is FeMnPbCuCrCd. Among them, the variation coefficient of Cu is the largest and the variation along the course is the biggest, and the influence of human activities is more serious than that of other heavy metals. The assessment results of heavy metal pollution in river sediment by the method of accumulation index show that the sediment is polluted by CD Pb and Cu in the simulated experiment of water level fluctuation. During flooding, the order of heavy metal content in sediment is FeMnPbCrCuCdd, and the degree of pollution is CdPbMnCuCrFe. The order of heavy metal content in sediment after water level retreat is FeMnPbCrCuCdCdand the degree of pollution is CdPbMnCuCrFe. The contents of heavy metals in sediments after water level receding were decreased, while the morphological changes of different elements were different. The CD release simulation experiments of Pb and Cu in sediments before and after flooding showed that the N / P ratio in overlying water was higher than 100 on average, showing strong eutrophic conditions. Phosphorus is the limiting factor of algae growth. The total number of algae and the content of chlorophyll a decreased first and then increased. The total amount of algae and chlorophyll a in the samples without shading showed a decreasing trend, which was consistent with the change trend of total phosphorus and total nitrogen concentration. However, the algae in shaded samples are difficult to grow and reproduce, so the contents of nitrogen and phosphorus have been increasing. The correlation analysis of heavy metal CD and the total amount of algae, chlorophyll a in water shows. There was a weak correlation or antagonism between them, and CD in water promoted the growth of some algae.
【學(xué)位授予單位】：重慶交通大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：X52

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