海洋沉积物中磷化氢的分布、释放与转化研究

IOCAS-IR > 海洋环流与波动重点实验室

	海洋沉积物中磷化氢的分布、释放与转化研究
其他题名	Study on the distribution characteristics, release process and transformation mechanism of MBP in marine sediments
	冯志华
学位类型	博士
	2008-06-06
学位授予单位	中国科学院海洋研究所
学位授予地点	海洋研究所
关键词	中国近海长江口磷化氢形成机制与转化释放通量海洋微藻
摘要	磷化氢（PH3）是磷循环的气相载体，以气体自由态和基质结合态（MBP）两种形式存在于环境中。自然环境中磷化氢的发现是对磷生物地球化学循环的重要补充，它在磷循环中的地位和作用及产生机制开始成为人们关注的热点。目前国内外在湖泊、陆地土壤及大气中已开展了较为广泛的研究，但是关于海洋中的研究还较少。开展磷化氢在海洋沉积物中的分布特征，及其释放通量、与其它磷形态的转化、对微藻生长的影响等行为研究对弄清海洋环境中磷化氢的迁移转化机制及其在磷循环中的作用和地位具有重要的科学意义。本论文以不同环境条件下的海洋沉积物为研究对象，采用野外实验与室内模拟相结合的方法，运用改进的柱前二次低温冷阱富集和气相色谱-氮磷检测器联用技术等分析手段，系统研究了海洋沉积物中磷化氢的分布特征、环境因子对其分布的影响、沉积物磷化氢向水体、大气中的释放、迁移、转化规律；初步了解了海洋沉积物中结合态磷化氢的分布特征及其释放通量；揭示了磷化氢对海洋环境的可能影响。主要研究结果如下： MBP广泛存在于海洋沉积物中。中国沿海表层沉积物中MBP的浓度范围为：0.89-25.86 ng/kg, dry，其分布也表现出一定的空间分布特征，在同一离岸断面上，有近岸浓度高，远岸浓度低的分布规律；在北黄海、南黄海、东海北部海域、东海南部海域和南海海域的平均浓度分别为：5.57±3.78、3.78±2.81、5.27±3.07、5.48±4.05 和 13.52±7.86 ng/kg dry，与其它海域相比，南海海域的MBP浓度要相对较高一些。长江口海域表层沉积物中MBP的浓度范围为：1.93-94.86 ng/kg, dry。其分布也表现出一定的空间和季节分布特征。上游河口沉积物中MBP的浓度要普遍高于下游河口，平均浓度分别为31.34和4.79 ng/kg, dry。靠近石洞口、竹园排污口以及黄浦江口的S3和S4站位处MBP的浓度要显著高于其它站位，季节平均浓度分别为43.01和61.54 ng/kg, dry。MBP浓度的季节差异并不显著，上游河口和下游河口MBP浓度表现出相似的季节变化特征，一般来说8月和11月要稍高于2月和5月。澳大利亚伊拉瓦拉海湾柱状沉积物中的MBP表现出一定的垂直分布特征。两个柱状沉积物样品均在中下层存在MBP的高值区，且该海湾MBP的含量要远高于中国近海及长江口海域MBP的含量，两个柱状沉积物中MBP的平均浓度分别为637.3和542.6 ng/kg, dry。环境因子与MBP含量关系的研究结果表明：较高的TP、OP、IP、OC、TN含量均有利于高浓度MBP的产生；TP、OP、OC与MBP含量之间存在着较强的线性相关关系，是控制MBP分布的主要因素；氧化还原电位与MBP含量存在着显著的线性负相关，说明还原环境更有利于沉积物中高浓度MBP的存在；平均粒径与MBP含量存在着一定的线性负相关，说明小粒径有利于高浓度MBP的存在；水深、上升流引起的扰动等也是影响MBP分布的可能原因。并且，在本论文对中国沿海沉积物、长江口沉积物和澳大利亚海湾沉积物的研究中，均得到了MBP含量与OP存在着强烈的线性相关关系，而与IP的线性相关关系较弱或不相关的结论，说明海洋沉积物中的MBP更可能来源于微生物对有机磷成分的降解。另外，长江口海域沉积物中MBP含量与上层海水中活性磷酸盐、总磷、叶绿素a的含量也存在着一定的线性相关关系，说明沉积物中磷化氢的释放可能会对上层水环境产生影响。静态箱法释放通量的研究结果显示，胶州湾海域沉积物存在着磷化氢的释放现象。沉积物-大气界面和水-大气界面磷化氢的释放通量分别为：27.77和17.37 ng/(m2•h)，该结果要高于Louisiana湿地、水稻田和太湖水体磷化氢的排放通量。并据此估算出胶州湾的磷化氢年排放量为75.75kg/y，高于太湖及比利时垃圾填埋场的磷化氢年排放量。不同底质沉积物释放磷化氢的顺序为：虾池沉积物>滩涂沉积物>海滩黑泥沉积物>海滩排污口旁的砂质泥；践踏能显著促进磷化氢的释放。磷化氢的释放通量与沉积物中MBP的含量有显著的线性相关关系；胶州湾养殖池、滩涂沉积物及海域水体是大气中磷化氢的重要来源，沉积物中的磷化氢可连续向上层水体或大气中释放。晴天，胶州湾近海海域空气中磷化氢的浓度范围为1.06-16.90 ng/m3，且表现出早上和傍晚高，中午时分相对较低的变化规律；空气中磷化氢的浓度与光照强度及释放源释放量的大小有关。利用室内模拟方法，研究了磷化氢在海水中的转化过程及其对海洋微藻生长的影响，并得出了一些初步结论。日光灯照射条件下，通入海水中的磷化氢可部分转化为磷酸盐和总磷，并且转化后主要以磷酸盐的形式存在。环境条件会对该转化过程产生影响，避光条件下，磷化氢的转化率较低，日光灯照射和紫外灯照射均能促进该转化过程，特别是紫外灯照射，促进效果显著；添加氧气或三价铁离子氧化剂也能促进该转化过程。微藻生长实验结果表明，适量磷化氢气体的通入，能显著刺激并促进磷限制条件下东海原甲藻和赤潮异弯藻的生长，但这种刺激作用并不是无限制的，后期刺激生长作用会变弱或停止生长；低量磷化氢气体的通入，刺激作用不明显；高量磷化氢气体的通入，则会抑制两种海洋微藻的生长。东海原甲藻和赤潮异弯藻对通入磷化氢的响应略有差异，后者对磷化氢的反应更为灵敏；次磷酸盐和亚磷酸盐也都能刺激两种海洋微藻的生长，但与磷化氢相比，其影响作用相对较小。本论文的初步研究结果表明，在磷的海洋生物地球化学循环中，需要考虑磷化氢的作用，其长期、连续的释放对磷循环的贡献不可忽视，并可能是磷限制海域赤潮形成的补充机制。
其他摘要	Phosphine, a volatile constituent of the global biogeochemical phosphorus cycle, has been proved to be widespread in the environment; however, its function and status in the biogeochemical recycle has not been identified so far. It exists in two different forms: free gaseous phosphine and matrix-bound phosphine (MBP). Now people have focused mainly on researches of phosphine in air, land, marsh and lake. Nevertheless, little information is available on the function of phosphine in marine environment. Therefore, it is of great significance to study the distribution, emission, transfer, transformation of phosphine in marine environment and its possible link to phosphorus cycle. Both field and laboratory experiments were carried out to study the distribution characteristics, emission flux, transformation mechanism of phosphine in marine sediments and its possible influence on the growth of micro-algae. Phosphine was analyzed by an improved GC-NPD method, coupled with cryo-trapping enrichment technology. The distributions of matrix-bound phosphine and environmental factors in marine sediments under different environments, such as the coast of China, the Changjiang River Estuary and Lake Illawarra in Australia were investigated. Then, the flux and estimating emission level of phosphine from sediment and water to atmosphere in Jiaozhou Bay were measured. Furthermore, the transformation process of phosphine and its possible role on the aquatic environment were represented. The result of this study not only contributes to the global biogeochemical phosphorus cycle, but also supplements the possible occurring mechanism of harmful algae blooms. The main results are given as follows: Matrix-bound phosphine (MBP) concentrations in surface sediments collected from 37 stations along the coast of China in 2006 are reported. MBP was found in all samples and the average concentration was 6.30 ng/kg dry weight (dw). The distribution of MBP showed certain spatial variation characteristics with high MBP concentrations at stations near to the coast. The average concentrations of MBP in the northern Yellow Sea, the southern Yellow Sea, the northern area of East China Sea, the southern area of East China Sea, and South China Sea were 5.57±3.78, 3.78±2.81, 5.27±3.07, 5.48±4.05 and 13.52±7.86 ng/kg dw respectively. The seasonal and spatial distributions of MBP in the Changjiang River Estuary were also studied and MBP ranged from 1.93 to 94.86 ng kg-1 dry with an average concentration of 17.14 ng kg-1 dw. The concentrations of MBP in the upper estuary were remarkably higher than those in the lower estuary which could be attributed to more pollutant inputs in the upper estuary. The concentrations of MBP also varied with seasons and generally showed a decreasing order of November > August > May > February. The vertical distribution of MBP in core sediment samples in Lake Illawarra showed that high MBP concentrations generally existed in the middle and bottom layers. The MBP concentrations in Lake Illawarra were remarkably higher than in other investigations. The relationships between MBP and the sedimentary environmental factors indicated that MBP was strongly influenced by various factors. High total phosphorus (TP), organic phosphorus (OP), organic carbon (OC), inorganic phosphorus and total nitrogen (TN) concentrations are favorable for the production of MBP; small grain size and low redox potential (Eh) favor high MBP concentrations; water depth, disturbances and hydrodynamics, etc. also have certain roles on MBP concentrations. The significant, strong correlations between MBP and OP also provided evidence to support the viewpoint that phosphine originated from OP decomposition by microorganisms under anaerobic conditions. Furthermore, it was interesting to find that there also existed positive linear relationships between the concentrations of soluble reactive phosphorus, TP, chlorophyll a in bottom water and MBP in sediments which might be very complicated and need further exploring. The emission fluxes of phosphine from sediments in Jiaozhou Bay were also studied; Average phosphine fluxes of 27.77 and 17.37 ng/(m2•h) from sediment and seawater to atmosphere were found respectively. A total of 75.75 kg/year phosphine was estimated to be released from Jiaozhou Bay. The phosphine fluxes varied in different kinds of sediments with the highest flux from sediment in culture farms for shrimp. Phosphine was also detected in the atmosphere in Jiaozhou Bay which might be influenced by the light intensities and emission sources. The transformation process of phosphine in seawater and its possible influences on the growth of marine microalgae were also studied. The effects of environmental factors on the transformation process of phosphine in seawater demonstrated that the phosphine concentration decreased quickly at the initial hours and kept constant thereafter. Most of the transformed phosphine existed in forms of orthophosphate in the seawater and other phosphorus forms, such as hypophosphite and phosphite might also exist. The effects of phosphine, hypophosphite and phosphite on the growth of marine micro-algae under phosphorus limitation showed that the three kinds of reduced phosphorus, especially phosphine, might stimulate the growth of P. donghaicense and H. akashiwo to certain degree. This work is the first comprehensive study of the distribution, release, transformation of MBP in marine sediments and its relationships with environmental factors which will lead to a better understanding of the phosphorus biogeochemical cycle in the marine environment.
页数	126
语种	中文
文献类型	学位论文
条目标识符	http://ir.qdio.ac.cn/handle/337002/1371
专题	海洋环流与波动重点实验室
推荐引用方式 GB/T 7714	冯志华. 海洋沉积物中磷化氢的分布、释放与转化研究[D]. 海洋研究所. 中国科学院海洋研究所,2008.

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