人类活动影响下胶州湾的大气干湿沉降与营养物质收支

发布时间：2018-04-25 11:41

  本文选题：生源要素 + 痕量元素　； 参考：《中国科学院大学(中国科学院海洋研究所)》2017年博士论文

【摘要】：伴随社会经济的迅猛发展,大气人为污染物质的排放也不断增多,它们可以通过沉降的方式进入海洋。因此,大气沉降作为陆源人为污染物质输送入海的重要途径之一,受到了国内外学者、政府的广泛关注。本学位论文聚焦我国北方地区受人类活动影响显著的典型半封闭海湾——胶州湾,系统研究了其化学组分的大气干湿沉降、生态效应与营养物质收支。本研究通过采集胶州湾2015年6月~2016年5月的气溶胶及大气干、湿沉降样品,聚焦高强度人类活动影响下近海半封闭性海湾主要生源要素(N、P、Si、S)及溶解态痕量元素(Al、Fe、Mn、Co、Zn、Se、Pb、Cd、Cr)的大气干、湿沉降(包括酸沉降)通量及其影响因素,综合运用多种方法(统计分析、富集因子、主成分分析以及气团后向轨迹模型)解析其来源及大气传输过程。同时,着重从大气营养物质沉降对海洋初级生产力、营养盐结构影响的角度,系统探讨了大气沉降对胶州湾生态系统的影响。在此基础上,系统综合大气沉降、河流输入、点源排污、海水养殖、沉积物—水界面扩散释放以及与黄海的水交换等营养物质收支过程,评估其收支状况,阐明胶州湾水体的营养物质源/汇格局。获得了如下的系统新认识:(1)胶州湾大气N污染极为严重,气象条件(降水量、风向)、当地自然/人为污染物的排放强度以及远距离传输是影响大气营养盐干、湿沉降浓度及通量的主要因素;气溶胶水溶性营养盐(N、P、Si)的干沉降速率呈现较为明显的月际变化;由于不同营养盐成分干沉降速率的较大差异,导致气溶胶中各营养盐浓度的比例与干沉降中相应成分的比例之间存在较大差异;气溶胶以及大气干、湿沉降中N、P、Si比例严重失衡,有机态N、P的大气沉降不容忽视;干、湿沉降,尤其是强降水会对表层海水的生源要素产生强力加富作用,促进浮游植物生长以及初级生产力的提高、改变表层水体的营养盐结构,进而对胶州湾浮游植物群落结构和粒级结构产生影响,加剧胶州湾生态系统的失衡。胶州湾大气各形态营养盐的干、湿沉降通量分别为NH_4-N(29.4、92.8)、NO_3-N(29.9、54.5)、NO_2-N(0.058、0.427)、DON(15.4、47.5)、PO_4-P(0.099、0.274)、DOP(0.165、0.448)、DSi(8.48、1.73)mmol·m~(-2)·yr~(-1);除DSi之外,湿沉降均占据主导地位。运用干沉降模型间接估算的胶州湾气溶胶NH_4-N、NO_3-N、NO_2-N、DON、PO_4-P、DOP以及DSi的干沉降速率分别为0.17±0.11、0.35±0.20、0.34±0.25、0.30±0.22、0.43±0.28、0.91±0.60和1.31±1.27 cm·s~(-1),季节变化较为明显。干、湿沉降均以无机氮为主,DON在N干、湿沉降中的比例分别为20.6%和24.3%,而DOP在P干、湿沉降中均占优势地位(62.5%和62.0%),表明有机态N、P的大气沉降不容忽视。胶州湾大气N、Si、P的主要来源分别为农业活动、土壤沙尘、人为排放与自然源的混合源。气团后向轨迹分析显示,来自西北(34.7%)和东南方向(42.8%)的降水气团对湿沉降的影响较大,而对于干沉降,来自西北方向气团(57.9%)的影响占据绝对主导地位。由于胶州湾表层海水的P限制,根据Redfield比值估算的大气沉降输入的P所支持的新生产力在春、夏、秋、冬季分别为1.94,1.15,1.86,1.15 mg C·m~(-2)·d~(-1)。尽管大气沉降所输入的P支持的平均新生产力较低,但雨季短时强降雨带来的大量营养物质的输入所支持的新生产力最高可达胶州湾平均初级生产力的25%。此外,干、湿沉降中极高的N:P比和极低的Si:N比加之NH_4-N的绝对优势地位,会改变表层水体的营养盐结构,恶化水体的P限制和Si限制,这可能是近年来胶州湾浮游植物群落结构和粒级结构改变以及优势种演替的一个重要原因。(2)胶州湾大气降水明显酸化,加之较高的电导率和S、N沉降通量,揭示了该区域处于较为严重的大气二次污染过程;SO_4~(2-)和NO_3~-是主要的致酸成分,而NH_4~+和nss-Ca~(2+)是主要的酸性中和成分,Ca~(2+)的严重缺乏可能是导致雨水酸性较强的一个重要原因;人为源是胶州湾大气水溶性离子的主导源。胶州湾大气降水的p H范围为3.84~6.91,雨量加权均值(VWM)低至4.77,酸雨频率高达71.4%。NH_4~+、SO_4~(2-)、NO_3~-、Ca~(2+)和Cl~-是主要的大气水溶性无机离子成分,其占比在气溶胶和雨水中均超过80%。NH_4~+超过Ca~(2+)成为最主要的阳离子,而SO_4~(2-)则为最主要的阴离子。S、N的大气沉降通量分别为20.17和28.92kg·ha~(-1)·yr~(-1),均以湿沉降为主。尽管目前胶州湾大气降水仍为硫酸型,但随着大气NO_x排放的增强以及对SO_2排放的严格控制,酸雨类型正逐渐向硝酸型转化。定量分析结果表明,海洋源、地壳源以及人为源对胶州湾大气化学成分的贡献率分别为28.7%、14.5%和56.8%。鉴于海洋浮游植物对大气SO_4~(2-)的贡献被忽视,其海洋源可能被低估。(3)胶州湾大气溶解态痕量元素浓度和沉降通量处全球中等水平,受复杂的气象条件(降水量、风速、风向)和污染物排放强度的影响,干、湿沉降痕量元素呈现较为明显的月际变化;胶州湾大气溶解态Al和Fe主要为地壳源,而其余7种元素主要是人为源,来自西北方向的气团/云团对研究区域大气溶解态痕量元素的浓度起主导作用;Mn、Zn、Co具有较高的干沉降速率,而典型人为源元素Pb、Cd、Cr的干沉降速率较低;短时强降雨会对表层海水的痕量元素产生加富作用,污染海洋环境,进而对浮游植物生长同时产生营养和毒害作用。胶州湾大气水溶性痕量元素的干、湿沉降通量分别为Al(19.3、29.2)、Fe(10.2、14.2)、Mn(21.6、24.2)、Co(0.154、0.090)、Zn(101.5、24.1)、Se(0.862、0.725)、Pb(0.175、2.21)、Cd(0.035、0.131)、Cr(0.083、0.669)mg·m~(-2)·yr~(-1),除Co、Zn、Se之外,均以湿沉降为主。利用干沉降模型间接估算的上述9种溶解态痕量元素的干沉降速率分别为1.29±1.60、1.27±1.66、2.33±1.48、1.67±0.94、1.98±2.22、0.51±0.29、0.12±0.13、0.15±0.12、0.17±0.10cm·s~(-1),表现出一定的季节变化特征。除Al、Fe之外,地壳源对其它痕量元素的贡献几乎可以忽略;来自西北方向的气团/云团在调查期间含有相对较高的溶解态痕量元素浓度,且发生频率最高,因此对调查区域大气溶解态痕量元素浓度起主导作用。干、湿沉降输入的溶解态Fe可以支持的生物固氮量为4.5×10~8~94.9×10~8 g N·yr~(-1),可占胶州湾总生物固氮量的4.9%~100%。(4)在胶州湾营养物质收支中,相对于河流输入、点源排污等陆源输入以及海水养殖排泄,大气沉降输入的营养物质占比较低,但与往年相比有所提高,表明大气沉降对陆源物质输送入海的作用逐渐增强;南黄海与湾内的水交换是胶州湾DOP和Cr的重要来源;除Zn以外,胶州湾水体整体表现为各类营养盐及痕量元素的汇;由于留存于水体中的N:P比较高,胶州湾今后仍可能长期处于P限制状态;量化胶州湾营养盐及痕量元素的各种来源/归宿以及输入/输出通量,对于评估胶州湾水体的富营养化特征和环境演变趋势有重要意义。近年来大气干湿沉降在胶州湾营养物质总外源输入中的比重有所上升;对于个别痕量元素如Zn,大气沉降也占据较大比例,表明大气沉降是胶州湾痕量元素的一个重要来源,且随着人为活动的增强,其近年来的输入作用有所增强。通过一年的水交换,留存于水体中可用于浮游植物初级生产的DIN、DIP和DSi分别为193×10~9 mol、2.04×10~9 mol和106×10~9 mol,N:P比接近100,而Si:N比接近0.5,因此可以预测,在没有大的环境演变前提下,胶州湾水体可能将长期保持P限制,而Si限制的状况将会有所减轻。本研究全面探讨了胶州湾生源要素及痕量元素的大气干、湿沉降特征及其来源和生态环境效应,进一步加深了对人为影响下胶州湾营养元素生物地球化学循环过程的理解,同时为深入研究半封闭型海湾对人类活动影响日益增强的响应过程及机制提供了数据支持和理论依据。
[Abstract]:With the rapid development of the social economy, the emission of atmospheric pollution materials is increasing, and they can enter the ocean through settlement. Therefore, the atmospheric settlement, as one of the important ways to transport the polluted materials into the sea, is widely concerned by the scholars at home and abroad and the government. This dissertation focuses on the north of China. The typical semi closed Bay, Jiaozhou Bay, which is significantly affected by human activities, has systematically studied the atmospheric dry and wet settlement, ecological effects and nutrient balance of its chemical components. This study was conducted by collecting aerosols and atmospheric dry, wet settling samples in the May ~2016 year of June 2015, and focusing on the semi closure of the coastal waters under the influence of high intensity human activities. The main source elements of the Bay (N, P, Si, S) and the dissolved trace elements (Al, Fe, Mn, Co, Zn, Se, Pb, Cd, etc.) are the atmospheric dry, wet deposition (including acid deposition) flux and its influencing factors, and use a variety of methods (statistical analysis, enrichment factor, principal component analysis and air mass backward trajectory model) to analyze its source and atmospheric transport process. The influence of atmospheric sedimentation on the primary productivity of the sea and the structure of the nutrient salt was discussed. The effects of atmospheric sedimentation on the Jiaozhou Bay ecosystem were systematically discussed. On this basis, the system integrated atmospheric sedimentation, river input, point source discharge, marine aquaculture, sediment water interface diffusion release, and water exchange with the Yellow Sea. The quality of revenue and expenditure process is evaluated and the source / sink pattern of the water body in Jiaozhou Bay is clarified. The following new knowledge is obtained: (1) the atmospheric N pollution in the Jiaozhou Bay is extremely serious, the weather conditions (precipitation, wind direction), the local natural / man-made pollutant emission intensity and the long distance transmission are the influence of the atmospheric nutrient salt dry, the wet settlement concentration The main factors of flux, the dry settlement rate of N, P, Si, showed obvious intermonthly change, and the proportion of the concentration of different nutrients in the aerosol and the proportion of the corresponding precipitation in the dry settlement, as a result of the large difference in the dry sedimentation rate of different nutrients, and the aerosol as well as the atmosphere. Dry, wet settlement, N, P, Si ratio is seriously unbalanced, organic state N, P atmospheric sedimentation can not be ignored; dry, wet settlement, especially strong precipitation will produce strong additive effect on the source elements of surface sea water, promote the growth of phytoplankton and increase the primary productivity, change the nutrient structure of the surface water body, and then to the phytoplankton community in Jiaozhou Bay The influence of structure and grain level structure aggravate the imbalance of the ecosystem in the Gulf of Jiaozhou. The dry of various forms of nutrients in the atmosphere of the Jiaozhou Bay are NH_4-N (29.4,92.8), NO_3-N (29.9,54.5), NO_2-N (0.058,0.427), DON (15.4,47.5), PO_4-P (0.099,0.274), DOP (0.165,0.448). The dry sedimentation rate of NH_4-N, NO_3-N, NO_2-N, DON, PO_4-P, DOP and DSi is 0.17 + 0.11,0.35 + 0.20,0.34 + 0.25,0.30 + 0.60 and 1.31 + 1.27 respectively, and the seasonal variation is more obvious. Dry and wet deposition is mainly inorganic nitrogen. The proportion of DON in N dry and wet settlement are 20.6% and 24.3% respectively, while DOP is dominant in P dry and wet settlement (62.5% and 62%), indicating that the atmospheric sedimentation of organic N and P can not be ignored. The main sources of N, Si and P in Jiaozhou Bay are agricultural activities, soil dust, human emissions and natural sources. The influence of precipitation from Northwest (34.7%) and southeast direction (42.8%) on wet settlement is great, and the influence of the northwest direction air mass (57.9%) is dominant for dry settlement. Due to the P limit of the surface sea water in the Jiaozhou Bay, the new productivity supported by the P of atmospheric sedimentation calculated according to the Redfield ratio is in spring, summer and autumn. In winter, 1.94,1.15,1.86,1.15 mg C / m~ (-2). D~ (-1). Although the average new productivity supported by the P supported by atmospheric sedimentation is lower, the new productivity supported by the input of a large number of nutrients brought by short rainfall in the rainy season is up to the 25%. of the average primary yield of the Jiaozhou Bay, in addition to the high N:P ratio and pole in wet deposition. The absolute dominance of lower Si:N than adding NH_4-N will change the structure of the nutrient salt of the surface water body and deteriorate the P and Si limits of the water body. This may be an important reason for the changes of the phytoplankton community structure and grain grade structure and the succession of the dominant species in the Jiaozhou Bay in recent years. (2) the precipitation in the Jiaozhou Bay is obviously acidified, and the higher conductivity is also found. The rate and S, N sedimentation flux reveal that the region is in a more serious two pollution process in the atmosphere; SO_4~ (2-) and NO_3~- are the main acid causing components, and NH_4~+ and nss-Ca~ (2+) are the main acid neutralization components. The serious lack of Ca~ (2+) may be an important cause of the strong rain acidity; the human source is the water solubility of the air in the Jiaozhou Bay. The P H range of the atmospheric precipitation in Jiaozhou Bay is 3.84~6.91, the rainfall weighted mean (VWM) is as low as 4.77, the acid rain frequency is as high as 71.4%.NH_4~+, SO_4~ (2-), NO_3~-, Ca~ (2+) and Cl~- are the main components of the water soluble inorganic ions, which are more than the most important cations in aerosols and rain water. SO_4~ (2-) is the most important anion.S, and the atmospheric deposition flux of N is 20.17 and 28.92kg. Ha~ (-1). Yr~ (-1), which are mainly wet precipitation. Although the atmospheric precipitation in Jiaozhou Bay is still sulphuric acid type, the acid rain type is gradually converted to the nitrate type with the increase of NO_x emission in the atmosphere and the strict control of the SO_2 emission. The results show that the contribution rates of marine sources, crustal sources and human sources to atmospheric chemical components in Jiaozhou Bay are 28.7%, 14.5% and 56.8%., respectively, in view of the neglect of the contribution of marine phytoplankton to atmospheric SO_4~ (2-), and its marine sources may be underestimated. (3) the concentration of dissolved trace elements in the atmosphere of the Gulf of Jiaozhou and the middle level of the settlement flux at the global level are complex. The influence of meteorological conditions (precipitation, wind speed, wind direction) and pollutant emission intensity, the trace elements in dry and wet deposition are more obvious monthly changes; the dissolved Al and Fe in Jiaozhou Bay are mainly crustal source, while the other 7 elements are mainly human sources. The concentration plays the leading role; Mn, Zn and Co have higher dry sedimentation rate, while the dry sedimentation rate of typical human source elements Pb, Cd, Cr is low; short time strong rainfall will enrich the trace elements in the surface water, pollute the marine environment, and then produce the nutrient and poison effects on the growth of phytoplankton. The water soluble trace in Jiaozhou Bay The wet settlement flux is Al (19.3,29.2), Fe (10.2,14.2), Mn (21.6,24.2), Co (0.154,0.090), Zn (101.5,24.1), Se (0.862,0.725). The dry sedimentation rate is 1.29 + 1.60,1.27 + 1.66,2.33 + 1.48,1.67 + 0.94,1.98 + 2.22,0.51 + 0.29,0.12 + 0.12,0.17 + 0.10cm s~ (-1), showing some seasonal variation characteristics. Apart from Al, the contribution of the crust source to other trace elements is almost negligible; the air mass / cloud from the northwest direction is contained in the investigation period. There is a relatively high concentration of dissolved trace elements and the highest frequency, so it plays a leading role in the investigation of the concentration of trace elements in the atmosphere. The dissolved Fe can support 4.5 * 10~8~94.9 x 10~8 g N. Yr~ (-1), and can occupy 4.9%~100%. (4) of the total biological nitrogen fixation in the Gulf of Jiaozhou Bay. In the nutrient budget, the input of land source and aquaculture are relatively low compared to the input of river, point source discharge and aquaculture, but it is higher than that in previous years, indicating that the effect of atmospheric sedimentation on the transport of terrestrial materials to the sea gradually increased, and the water exchange between south the Yellow Sea and the bay is important for the DOP and Cr in the Gulf of China. In addition to Zn, the Jiaozhou bay water body is the aggregate of all kinds of nutrients and trace elements. Because of the high N:P remaining in the water body, the Jiaozhou Bay may still be in the P limit for a long time, and the various sources / destination and input / output flux of the nutrients and trace elements in the Jiaozhou Bay are quantified to assess the wealth camp of the Jiaozhou bay water body. In recent years, the proportion of atmospheric and wet precipitation in the total exogenous input of nutrients in Jiaozhou Bay has risen, and the atmospheric sedimentation is also a large proportion for some trace elements, such as Zn, indicating that atmospheric sedimentation is an important source of trace elements in the Gulf of Jiaozhou and increases with human activities. Its input effect has been enhanced in recent years. Through a year of water exchange, DIN, DIP and DSi are 193 x 10~9 mol, 2.04 x 10~9 mol and 106 x 10~9 mol, N:P ratio close to 100, and Si:N ratio close to 0.5, so that the Jiaozhou bay water body may be predicted without large environmental evolution. The P limit will be maintained for a long time, while the condition of the Si limit will be reduced. This study comprehensively explored the atmospheric dry, the characteristics of the wet deposition, the source and the ecological environment effect of the source and trace elements of the Jiaozhou Bay, and further deepened the understanding of the biogeochemical cycle process of the nutrient elements in the Jiaozhou Bay under the influence of human beings. The semi closed bay provides the data support and theoretical basis for the response process and mechanism of the increasing impact of human activities.

【学位授予单位】：中国科学院大学(中国科学院海洋研究所)
【学位级别】：博士
【学位授予年份】：2017
【分类号】：X51;X55
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本文编号：1801160