【作者】 张国玲；

【导师】 任景玲；

【作者基本信息】 中国海洋大学 ， 分析化学， 2009， 硕士

【摘要】 铝是陆源物质向海洋输送的一种有效示踪剂,可以用来指示沙尘在大洋中沉降的位置和规模、示踪不同水团的运动,因此铝的海洋生物地球化学循环研究越来越受到科学家们的广泛关注。目前,关于溶解态铝在海洋中的清除机制研究方面还存在较大的争议。本文在此背景下,对桑沟湾养殖区和浙闽沿岸海域铝的分布、季节变化及影响因素进行了初步的研究,深化人们对铝在浮游植物生物量相对较大的养殖型海湾和受陆源径流影响相对较大的沿岸区域生物地球化学循环过程的认识。根据2006年4月、7月、11月和2007年1月对桑沟湾进行的调查,分析了水体、悬浮颗粒物、表层沉积物中铝的分布及季节变化。结果表明,桑沟湾溶解态铝的分布呈现出明显的季节变化,夏季最高,浓度为64.1±45.1 nmol/L;春、秋季次之,浓度分别为60.8±29.1 nmol/L、60.3±15.5 nmol/L;冬季最低,浓度为31.2±9.6 nmol/L。因悬浮颗粒物的来源及类型不同,春季和冬季颗粒物中铝的含量较高,夏季和秋季颗粒物中铝的含量较低;颗粒物中铝主要以残渣态存在。颗粒物中可交换态铝(醋酸提取态)在颗粒态铝中所占的比例为春季和夏季比较高,其中夏季醋酸提态所占的比例可高达(2.19±0.88)%。春、夏、秋、冬四个季节表层沉积物中铝的平均含量分别为6.85%±0.60%、6.70%±0.68%、7.09%±0.47%、6.83%±0.50%,其含量季节变化不大,分布趋势主要受陆源输入的影响。根据获得的不同季节桑沟湾溶解态和颗粒态铝的含量,讨论了颗粒物对溶解态铝分布的影响并计算了铝在颗粒物表面的分配系数。铝的界面分配系数Kd的范围为0.24×105～1.3×106 mL/g,平均值为3.6×105±2.6×105 mL/g,其中SPM的范围为8.0～60.6 mg/L。根据箱式模型,考虑桑沟湾中各种来源铝的贡献和桑沟湾中溶解态铝的总量,在水量平衡和盐量平衡的基础上初步估算了溶解态铝的存留时间约为(36±17) d。2007年5月和2008年5月分别对浙闽沿岸海域溶解态铝进行了调查研究,初步分析了研究区域水体中溶解态铝的分布、年际变化及其影响因素,并在海上进行了藻类现场培养,初步探讨生源颗粒物对铝的清除作用。结果表明,2007年5月浙闽沿岸海域表、底层溶解态铝的平均浓度分别为49.6±40.9 nmol/L和54.8±25.6 nmol/L;2008年5月浙闽沿岸海域表、底层溶解态铝的平均浓度分别为45.0±29.2 nmol/L和53.4±25.1 nmol/L。由此可见,浙闽沿岸海域溶解态铝含量的年际变化不大。两个航次中溶解态铝的水平分布规律基本类似,均表现为近岸浓度较高,随离岸距离的增加浓度逐渐下降,表现出明显的陆源输入的特点。选取受长江冲淡水影响的S1断面和位于台湾海峡北部的S6断面来讨论断面分布,结果发现受长江冲淡水、浙闽沿岸水及台湾暖流等水团的影响,溶解态铝的断面分布基本呈现出近岸高、外海低的特点。但对于特定断面而言,由于受到断面所处位置、长江径流量的年际变化、水体中悬浮颗粒物含量和浮游植物生物量等影响因素的共同作用,分布特点略有差异。对典型站位溶解态铝等要素的垂直变化规律讨论后发现,溶解态铝垂直分布规律基本一致,为中层最小值类型。即表层浓度较高,中层最小,底层浓度随着深度的增加而增大。这种剖面分布反映了研究区域溶解态铝有两个主要来源,表层水体主要受长江冲淡水和浙闽沿岸水等陆源输入的影响,底层则受沉积物再悬浮和悬浮颗粒物的吸附解吸作用的影响。对于发生水华的站位,溶解态铝的垂直剖面变化规律与硅酸盐基本类似,显示出营养盐型的剖面特点,而与叶绿素含量反相关。叶绿素含量比较高的站位,表层溶解态铝的浓度明显降低,藻类现场培养过程中也发现了这一现象,表明藻类的水华过程在一定程度上对水体中的溶解态铝产生了清除作用,具体的机理仍需进一步深入探讨。更多还原

【Abstract】 Aluminum is an ideal tracer for the input of terrestrial materials into the ocean. It can be used to indicate the location and magnitude of aeolian dust deposition and to trace the movements of different water masses in the ocean. Therefore, the research on marine biogeochemical cycle of aluminum has attracted more and more attention by scientists. At present, there still exist controversies on the scavenging mechanism of dissolved aluminum in the ocean. Under this background, the distributions, seasonal variations and the influencing factors of aluminum in the Sanggou Bay and coastal area of Zhejiang and Fujian are primarily studied in this article.Four cruises were carried out in the Sanggou Bay in April, July and November of 2006 and January of 2007. This dissertation presents the results of the distributions and seasonal variations of aluminum in the seawater, suspended particulate matter and surface sediments. The distributions of dissolved aluminum in the Sanggou Bay show obvious seasonal variations. The concentrations of dissolved aluminum in four seasons are 60.8±29.1 nmol/L, 64.1±45.1 nmol/L, 60.3±15.5 nmol/L and 31.2±9.6 nmol/L, respectively. Due to different sources and types of suspended particulate matter, the concentrations of particulate aluminum are higher in the spring and the winter than that in the summer and the autumn. Particulate aluminum exists mainly in residual form. The exchangeable portion of the particulate aluminum is high in the spring and the summer, which can reach as high as (2.19±0.88) % in the summer. The average concentrations of aluminum in the surface sediments of four seasons are 6.85%±0.60%, 6.70%±0.68%, 7.09%±0.47% and 6.83%±0.50%, respectively, which have no obvious seasonal variations. The distributions of aluminum in the surface sediments are mainly affected by land-source input. Partitioning of aluminum between solid and solution phases is described by distribution coefficient, Kd, which varies from 0.24×105 to 1.3×106 mL/g with a mean of 3.6×105±2.6×105 mL/g. Based on the simple box model, a residence time of 36±17 days for dissolved aluminum has also been worked out.Two cruises were carried out in coastal area of Zhejiang and Fujian in May of 2007 and 2008, respectively. The distributions, annual variations and the influencing factors of dissolved aluminum are primarily studied in this area. At the same time, in situ culture experiment was carried out during the cruise of May 2008, in order to discuss the effects of biogenic particles on scavenging of dissolved aluminum in the seawater. The results show that, the average concentrations of dissolved aluminum in the surface and bottom layers of the coastal area of Zhejiang and Fujian in May of 2007 are 49.6±40.9 nmol/L and 54.8±25.6 nmol/L, respectively; the average concentrations of dissolved aluminum in the surface and bottom layers of the coastal area of Zhejiang and Fujian in May of 2008 are 45.0±29.2 nmol/L and 53.4±25.1 nmol/L, respectively. Thus it can be seen, the annual variations of dissolved aluminum in the coastal area of Zhejiang and Fujian are relatively small. The horizontal distributions of dissolved aluminum in two cruises show similar profiles, with higher concentrations in the coastal area and decreasing by the distance of offshore, which indicate the characteristic of land-source input.The distributions of the dissolved aluminum in S1 and S6 sections are influenced by several water masses, such as Changjiang diluted water, Zhe-Min coastal water and Taiwan Warm Current. Thus the concentrations of dissolved aluminum decrease with the distance off the coast. However, there is a slightly different distribution characteristic for the particular section due to the combined influencing factors including the location, Changjiang runoff, suspended particulate matters and phytoplankton biomass.The vertical profiles of dissolved aluminum in typical stations of the coastal area of Zhejiang and Fujiang are basically identical, with the middle-depth minimum types. The concentration of dissolved aluminum is higher in the surface and near bottom, while is lower in the mid-depth. This kind of profile indicates two main sources of dissolved aluminum in the study area. The dissolved aluminum in the surface water mainly comes from the Changjiang diluted water and other riverine inputs in Zhejiang and Fujian provinces. The source of dissolved aluminum in the bottom water comes from the re-suspension of sediments and surface adsorption and desorption reactions of suspended particulate matter. The concentrations of dissolved aluminum show negative correlations with the chlorophyll contents at the surface layers of bloom stations. The similar phenomenon also exists in the culture experiments. So in certain extent dissolved aluminum can be scavenged by phytoplankton during spring bloom. But the scavenging mechanism needs further research.更多还原