本文選題：光照　切入點(diǎn)：近岸海水　出處：《中國(guó)海洋大學(xué)》2014年碩士論文　論文類(lèi)型：學(xué)位論文

【摘要】：海洋在全球汞循環(huán)中發(fā)揮重要作用。汞的氧化還原作用是推動(dòng)溶解性氣態(tài)汞(DGM)產(chǎn)生和釋放的重要過(guò)程。研究近岸表層海水中二價(jià)汞和零價(jià)汞之間相互轉(zhuǎn)化的反應(yīng)機(jī)制，有助于了解海洋釋放對(duì)大氣汞庫(kù)的貢獻(xiàn)。本文以青島近海表層水為研究對(duì)象，研究了不同波長(zhǎng)紫外光照下汞的還原反應(yīng)和氧化還原總反應(yīng)。通過(guò)測(cè)定溶解性氣態(tài)汞和活性汞(RHg)的含量，探討懸浮顆粒物(SPM)和微生物對(duì)還原反應(yīng)、氧化還原總反應(yīng)的影響。結(jié)果表明： 還原反應(yīng)： 1）近岸表層海水中DGM的釋放量逐漸降低，累積釋放量逐漸升高，升高速度越來(lái)越慢，最后接近穩(wěn)定。UVA、UVB和黑暗條件下，還原反應(yīng)在5個(gè)小時(shí)內(nèi)基本完成，還原反應(yīng)速率常數(shù)分別為0.983h-1、0.306h-1、0.174h-1。黑暗環(huán)境中，汞的還原反應(yīng)仍舊進(jìn)行。紫外光促進(jìn)近岸表層海水中汞的還原反應(yīng)，隨著波長(zhǎng)的增大，還原反應(yīng)速率和釋放量增大。 2）微生物和SPM對(duì)還原反應(yīng)速率的影響：黑暗環(huán)境下，海水中SPM和微生物對(duì)還原反應(yīng)速率的影響小。UVA光照下SPM和微生物對(duì)還原反應(yīng)速率的影響顯著。光致還原反應(yīng)占66%，微生物使還原反應(yīng)速率降低了22%，SPM則使還原速率提高了55%。UVB光照下SPM和微生物對(duì)還原反應(yīng)速率的影響介于兩者之間。光致還原反應(yīng)占63%，微生物還原作用占4%，SPM使還原速率提高了32%左右。 3）水體理化性質(zhì)、汞形態(tài)和含量的不同導(dǎo)致青島近海和黃河口表層水中汞的還原反應(yīng)存在明顯差異。 氧化還原反應(yīng)： 1）Hg2+和Hg0的相互轉(zhuǎn)化并不是簡(jiǎn)單的可逆反應(yīng)，可能存在介于兩者之間的中間產(chǎn)物。 2）微生物和SPM對(duì)近岸表層海水中氧化還原反應(yīng)的影響：黑暗條件下，未知還原起主導(dǎo)作用，微生物抑制還原反應(yīng)、促進(jìn)氧化反應(yīng)，SPM促進(jìn)DGM的產(chǎn)生、抑制RHg的產(chǎn)生。UVA光照下，，微生物促進(jìn)氧化還原反應(yīng)，SPM抑制氧化還原反應(yīng)。UVB光照下，微生物促進(jìn)還原反應(yīng)、抑制氧化反應(yīng)，SPM抑制DGM的產(chǎn)生、促進(jìn)RHg的產(chǎn)生。 3）自然光照條件下，近岸表層海水中DGM和RHg凈含量分別在295pg/L-960pg/L和901pg/L-5912pg/L的范圍內(nèi)變化。DGM和RHg均隨光照強(qiáng)度呈單峰變化，早晨、晚上含量低，中午達(dá)到峰值。DGM和RHg凈含量在0.01水平上呈顯著正相關(guān)性。不同波段的自然光中，DGM、RHg凈含量與UVB之間的相關(guān)系數(shù)最大，與UVC的相關(guān)系數(shù)最小。
[Abstract]:Oceans play an important role in the global mercury cycle. Mercury oxidation reduction is promoting dissolved gaseous mercury (DGM) and an important process release. Reaction mechanism of mutual transformation between the two price of mercury in coastal seawater and mercury, are helpful to understand the contribution of gas mercury release marine base. This paper takes Qingdao coastal surface water as the research object, study the different wavelength UV light reduction reaction and oxidation reduction reaction. The total mercury determination of dissolved gaseous mercury (RHg) and the activity of mercury content of suspended particulate matter (SPM) and microbial reduction reaction, the influence of the redox reaction. The results showed that the total:
Reduction reaction:
1) the release amount of DGM in the coastal surface seawater decreased gradually, the cumulative release rate gradually increased, rising more slowly, and finally close to the stable.UVA, UVB and dark conditions, the basic completion of the reduction reaction in 5 hours, the reaction rate constants were 0.983h-1,0.306h-1,0.174h-1. in a dark environment, the reduction reaction of mercury is still carried out. Promote the UV reduction reaction of mercury in coastal seawater, with the increase of the wavelength, reaction rate and release amount increased.
2) effect of microbial and SPM on reaction rate: the dark environment, SPM and microbial in seawater affect the reduction reaction rate of small.UVA light SPM and microorganism had significant effects on the reaction rate. The photoreduction reaction accounted for 66%, the microbial reduction reaction rate decreased by 22%, the reduction rate of SPM improved 55%.UVB light SPM and microbial effect on reaction rate between the two. The photoreduction reaction accounted for 63%, accounted for 4% of microbial reduction, the reduction rate of SPM increased by about 32%.
3) the physical and chemical properties of the water body, the difference of mercury form and content lead to significant difference in the reduction of mercury in the surface water of the Qingdao and the Yellow River Estuary.
Redox reaction:
1) the mutual transformation of Hg2+ and Hg0 is not a simple reversible reaction, and there may be intermediate products between the two.
2) and microbial SPM reduction effect on oxidation in coastal seawater: dark conditions, unknown reduction plays a dominant role in microbial inhibition reaction, promote the oxidation of SPM, promote the production of DGM, inhibited the production of RHg.UVA light, promote microbial redox reaction, SPM inhibited the redox reaction of.UVB light under the illumination of the microbially mediated inhibition of oxidation reaction, reduction reaction, SPM inhibited the production of DGM, promote the production of RHg.
3) under natural light conditions, the net content of DGM and RHg in the coastal surface seawater were in the range of 295pg/L-960pg/L and 901pg/L-5912pg/L in the changes of.DGM and RHg decreased with the light intensity showed a unimodal curve, morning and evening peak at noon low content of.DGM and RHg net content showed a significant positive correlation at the level of 0.01 different bands. Natural light, DGM, the correlation coefficient between RHg net and the content of UVB maximum, minimum and the correlation coefficient of UVC.

【學(xué)位授予單位】：中國(guó)海洋大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類(lèi)號(hào)】：P734.22

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