【作者】 李建兵；

【导师】 张经；

【作者基本信息】 中国海洋大学 ， 海洋化学， 2009， 博士

【摘要】 磷化氢（PH3）作为磷的一种还原态化合物,分为自由态磷化氢（气态PH3）和基质结合态磷化氢（MBP）,前者主要存在于大气、沼气中,后者存在于土壤、沉积物、污泥中,PH3的研究已经成为磷生物地球化学循环研究的一部分。以往的研究主要集中于陆地生态系统中,因此研究海洋环境中PH3对于认识磷的生物地球化学循环及其环境影响具有重要的意义。首先本文以青岛近岸大气为研究对象,对海洋性大气中气态PH3昼夜和季节变化规律及影响因素进行了较为系统的研究;检测到大气中存在MBP,对海洋性大气中PH3及存在影响因素进行了讨论,并估算了其对海洋中磷输入的贡献;同时以典型陆架黄海、东海、长江口、海南东北部等为研究对象,研究了沉积物中MBP的时空分布规律,探讨了影响海洋沉积物中MBP存在的重要环境因素及MBP对于环境变化的潜在影响和意义,为认识磷的全球循环尤其是中国近海区域的磷循环提供科学依据。本论文的主要研究成果如下:1.参考国内外文献在实验室建立了大气及沉积物中PH3的毛细柱二次富集—气相色谱法测定痕量PH3的方法,系统的研究了富集柱材料、富集温度、色谱条件等因素对气态PH3检测的影响,筛选出效果更佳的富集材料PLOT Q毛细柱,解决了测定海洋性大气中水分引起柱涂层脱落问题。该方法可避免氧化亚氮和甲烷的干扰。沉积物样品的可靠性试验证明避光冷冻条件下样品在两个月内是稳定的。大气和沉积物中PH3检测限分别为0.01 ng·m-3和0.02 ng·kg-1、精密度分别为<3.0%和<20%、线性范围为0.56 pg-5.6 ng,与国外同类方法相当。2.自2005年10月至2006年8月对青岛八关山大气样品中气态PH3进行了研究,结果表明青岛大气中气态PH3的浓度范围为0.01～14.86 ng·m-3,平均浓度为1.14 ng·m-3。青岛近岸大气中气态PH3浓度有明显的季节和昼夜变化规律,其中季节变化是夏季>春季>秋季>冬季,昼夜变化是早晨>傍晚>中午。大气中气态PH3浓度明显受温度、光照、来源及风向等各种气象因素的影响。气态PH3在中国大陆和黄、东海上空大气中迁移,参与了区域性大气中磷生物地球化学循环,每年大约16×105 mol磷通过气态PH3形式从青岛大气输送到黄海低层大气中,气态PH3从陆地向海洋输送尤其是向磷限制水体中转移可能是磷循环一个尚未深入认识的重要过程。3.对2004年3月到2005年12月期间在伏龙山采集的气溶胶样品进行了研究,发现大气中存在PH3的另一种形态—基质结合态磷化氢（MBP）,青岛大气中MBP浓度范围在0.01～22.63 pg·m^-3,年平均值为1.02 pg·m^-3,存在明显的季节性差异,秋季>冬季>春季、夏季。大气中MBP受气溶胶来源、气溶胶矿物组成、湿度或降雨、MBP本身物化性质等的影响和控制。陆源大气中MBP大约是海洋大气中MBP的6倍,并且估计黄海大气中MBP沉降通量大约为0.0189μmol·m^-2y^-1,每年通过MBP形式向黄海输送大约7.57×105 mol磷,约占PH3从青岛向黄海输送的一半,表明大气中MBP也是大气中还原态磷循环中重要的一部分。4.于2004年至2008年在对中国近海部分区域采集沉积物进行了研究,结果表明MBP不仅存在于中国温带近海区域沉积物中,甚至在热带地区也存在,如在黄海、长江口、东海、海南东北部近岸、胶州湾、桑沟湾沉积物中MBP含量分别为0.19～38.24 ng·kg^-1、0.1～169.4 ng·kg^-1、0.51～23.1 ng·kg^-1、0.21～5.45 ng·kg^-1、0.34～17.15 ng·kg^-1、2.11～71.79 ng·kg^-1,在胶州湾周边河流、海南东北部河流沉积物中MBP含量分别为0.28～319 ng·kg^-1、nd～82.1 ng·kg^-1,在海南东北部土壤、潟湖和红树林沉积物中MBP含量分别为nd～4.88 ng·kg^-1、1.34～12.74 ng·kg^-1和0.76～42.21 ng·kg^-1。5.沉积物中MBP含量存在季节性差异,如长江口及附近海域、桑沟湾、海南东北部的文昌文教河、红树林夏季沉积物中MBP高于秋、冬季;在长江口、东海沉积物中MBP含量从近岸向陆架呈带状分布并且向东逐渐减少;在黄海高含量MBP主要存在于黄海中部和北部靠近桑沟湾养殖区的沉积物中;同一条河流下游沉积物中MBP含量一般要高于上游沉积物中MBP;沉积物中MBP具有明显的垂直分布特征,高浓度MBP存在于沉积物还原性强的底层或次表层。6.沉积物尤其是海洋沉积物中MBP的含量、存在和分布受到沉积物类型、温度、有机质、氧化还原环境、pH值等多种环境因素的控制和影响。比表面较大的粘土有利于MBP赋存;温度较高（如夏季）有利于MBP的产生和积累;有机质为生物活动提供物质和还原环境、厌氧/缺氧水体有助于磷化氢生成;接近中性的pH值有助于磷化氢的保存;与之相反的环境如个别站位（砂质类型沉积物、较低pH值或酸性土壤等）也发现了MBP的存在甚至高浓度MBP存在暗示着沉积物中MBP的控制因素非常复杂,可能存在其它未知影响因素。7.研究了中国近海沉积物中MBP的分布和存在影响因素,为进一步认识全球磷循环尤其是中国近海沉积物中磷循环提供了依据。对海南沉积物、土壤中MBP的研究,填补了热带MBP研究方面的空白,完善了全球沉积物中MBP的分布,绘制了全球磷化氢循环图、补充了全球磷循环中的磷化氢相关数据。并结合文献提出了沉积物中MBP在早期成岩过程中的形成机理图。尽管PH3是沉积物中含量较低的一种磷存在形态,但由于其不稳定、转化速率比较快等特点,是沉积物中值得关注的一种磷存在形态。更多还原

【Abstract】 Phosphine （PH3）, as a kind of reduced phosphorus compounds in the natural enviroment, exists in two different forms, i.e. free phosphine （Gaseous PH3） and matrix bound phosphine （MBP）. The former has been detected in the atmosphere and biogas in urban and suburban areas. The latter was shown to be ubiquitously present in soils, sediments, sewage slurry etc. PH3 has been proven to participate in the global phosphorus biogeochemical cycle, but most previous studies were mainly focused on terrestrial ecosystems. Therefore studies on the biogeochemistry of PH3 in marine environments will be helpful to the understanding of the phosphorus biogeochemical cycles, and its potential effect on the environment especially the seas.In the present dissertation, the diurnal and seasonal variations of gaseous PH3 in the inshore atmosphere are studied and MBP was detected in Qingdao atmosphere for the first time. Environmental and meteorologic factors are found to influence the occurring and distribution of PH3 in Qingdao atmosphere and the contribution of atmospheric PH3 to the sea is estimated on a local scale. The distributions of MBP in sediments and the influence of environmental factors are investigated in the coastal areas of China, i.e. the Yellow Sea and the East China Sea shelf, Changjiang Estuary, northeastern Hainan Island, and some typical rivers around these areas. These studies contribute to understand not only phosphorus biogeochemical cycle, but also the possible impact of PH3 on marine ecosystem. The main research work is as follows:1. A chromatographic method using capillary column as a trap has been developed in lab to determine PH3 in atmosphere and sediments. The detection limits are 0.01 ng·m-3 and 0.02 ng·kg-1, and the precisions are <3% and <20% for air and sediments, respectively. The influence of cryogenic trap and chromatographic operation conditions were studied to obtain optimum results. The method avoids the interference of nitrous oxide and water vapor by using PLOT Q capillary as enrichment column. MBP in the marine sediments was digested by using sulfuric acid. Sediment sample storage experiments have been done to test reliability of the storage procedure used in this study, and the results showed that the effects of storage appear negligible in two months.2. Gaseous PH3 in the inshore atmosphere was observed from October 2005 to August 2006 at a coastal site of the Yellow Sea in China. The concentration of gaseous PH3 ranged from 0.01 to 14.86 ng m^-3 with an average of 1.14 ng m^-3. The concentration showed a diurnal variation in gaseous PH3 with the peak occurring at morning and the lowest point at noon. An obvious seasonal variation of atmospheric gaseous PH3 was found, with the gaseous PH3 levels in the summer higher than those in the winter. The gaseous PH3 levels in the atmosphere were apparently affected by temperature, radiation, sources and other meteorological factors. The data indicate that gaseous PH3 can be transported between the terrestrial and inshore atmosphere of Qingdao and the Yellow Sea or the East China Sea in both directions. The study increases evidence that gaseous PH3 participates within the global biogeochemical phosphorus cycle in phosphorus transport from land and inshore waters to the sea where commonly phosphorus is scarce and where gaseous PH3 inflow could be of important.3. MBP in the inshore atmosphere was observed from March 2004 to December 2005 at a coastal site of the Yellow Sea in China. The MBP was first detected in atmosphere and its concentration ranged from 0.01 to 22.63 pg·m^-3 with an average of 1.02 pg·m^-3. An obvious seasonal variation of atmospheric MBP was found with autumn>winter>summer, spring. The MBP levels in the atmosphere were apparently affected by aerosol source, aerosol mineral composition, humidity or rainfall and MBP physicochemical properties. MBP in terrestrial atmosphere is six times higher than those in marine atmosphere. MBP deposition flux is about 0.0189μmol·m^-y^-1 in the Yellow Sea,that is 7.57×105 mol MBP-phosphorus is deposited to the Yellow Sea via atmosphere each year which is half of free phosphine deposition flux. Atmospheric MBP V deposition plays an important role as gaseous PH3 in determining the biogeochemistry of phosphorus especially reduction state phosphorus in coastal and shelf regions.4. MBP in the coastal sediments of China were investigated from 2004 to 2008. MBP occurs from temperate zone to tropical zone. For example, MBP in surface sediments of the Yellow Sea, Changjiang Estuary, the East China Sea, the coast of northeast Hainan, Jiaozhou Bay, Sanggou Bay are 0.19～38.24 ng·kg^-1, 0.1～169.4 ng·kg^-1, 0.51～23.1 ng·kg^-1, 0.21～5.45 ng·kg^-1, 0.34～17.15 ng·kg^-1, 2.11～71.79 ng·kg^-1, respectively, while MBP in river sediments around Jiaozhou Bay and northeast of Hainan are 0.28～319 ng·kg^-1 and nd～82.1 ng·kg^-1, respectively. MBP in soils, lagoon and mangrove surface sediments are nd～4.88 ng·kg^-1, 1.34～12.74 ng·kg^-1 and 0.76～42.21 ng·kg^-1, respectively.5. The concentration of MBP in the sediments showed seasonal variation, with the MBP levels in the summer higher than those in the autumn and winter in the Changjiang estuary, Sanggou Bay, Wenchang River and Wenjiao Rive, and Mangrove. The distribution of MBP in surface sediments showed certain spatial variation with MBP concentrations decreasing from the coast to the shelf in Changjiang Estuary and the East China Sea. Higher MBP was found in the central and northern of the Yellow Sea adjacent Sanggou Bay. The vertical distribution of MBP in Jiaozhou Bay, Changjiang Estuary and Mangrove sediments showed that higher MBP generally occurred in the bottom or subsurface layer with strong reducing conditions.6. Environmental factors such as types of sediments, temperature, organic matter, redox conditions, pH were found to affect levels and distribution of MBP in sediments. Clay sediments are favorable for MBP accumulation due to large surface area and adsorption pots, and reducing condition, anoxia water, and neutral condition is also favor to the exsistence of MBP. Strong correlations between temperature, organic matter and MBP not only proved their effect on MBP in the sediments, but also showed that biological activity may control MBP production. However, MBP was found in some land sediments with lower pH or acid soils imply that MBP production and elimination are complicated, and more studies should be done.7. The studies on PH3 in the coastal areas of China improved our understanding of global biogeochemical phosphorus cycle Global PH3 cycles and global phosphorus biogeochemical cycles including PH3 are drawing based on the reference and this work. Early diagenesis schematic diagram of PH3 in the sediments was established. PH3, as a phosphorus species, is unstable and easily converted to other phosphorus compound. Although PH3 content in natural environment is low, it is an potential link in phosphorus biogeochemical cycle.更多还原