黄河三角洲土壤及其红粘层的地球化学特征与环境意义

发布时间：2018-04-19 13:45

本文选题：黄河三角洲 + 红粘层　；参考：《中国科学院烟台海岸带研究所》2016年博士论文

【摘要】：黄河三角洲是受到黄河来水来沙、尾闾流路变迁、全球气候变化等自然因素和农业耕种熟化、城镇化、工业化等人类活动交互作用、叠加影响的区域。目前对气候变化、人类活动和陆海相互作用多重影响下黄河三角洲区域土壤环境质量、土壤发生发育过程和土壤沉积物物质链关系缺乏一个整体认识。本论文基于黄河三角洲地区的42个典型类型土壤剖面(182个土壤样品)和26个临近海域表层沉积物样品,分析了土壤基本理化性质、土壤重金属元素与稀土元素、有机氯农药和石油烃等有机污染物、土壤原状土和胶体的矿物组成、化学组成、磁学性质等地球化学特征、土壤和沉积物放射性铅同位素和稳定性碳、氮同位素,表征了黄河三角洲地区土壤由陆到海的土壤质量特征;探讨了无机元素和有机污染物的土壤环境地球化学行为及来源;揭示了黄河三角洲土壤剖面红粘层的时空分布、地球化学特征和陆海相互作用下的环境意义。这些研究成果可为高强度人类经济活动及强烈陆海交互作用下黄河三角洲区域生物地球化学循环与可持续发展提供基础数据和科学依据,具有重要的科学意义和现实的指导意义。本研究的主要结果包括以下几个方面:(1)黄河三角洲在滩涂、湿地、棉田、粮田、菜地由海到陆的利用方式和空间过渡下,土壤盐分逐渐降低,土壤结构和肥力水平逐渐提高。其中,滩涂土壤结构较差,肥力水平很低,代表了该地区自然成陆条件下的原始土壤理化性质特征。滩涂发育为湿地后,湿地淹水的环境及丰富的植被,使得在该利用方式下土壤粘粒、有机质、氮、磷等含量显著提高。湿地开垦为农田后,人为改良使得土壤脱盐脱碱显著,明显提高了土壤供氮、供磷强度,但人类活动加剧了土壤团聚体的破坏以及有机质的释放。(2)黄河三角洲土壤重金属、有机氯农药和石油烃的整体含量较低,目前环境生态风险不高。土壤重金属在黄河河岸和三角洲南部区域含量有升高趋势;有机氯农药中相对活跃组份(γ-HCH和o,p’-DDT)和相对稳定组份(β-HCH和p,p’-DDE)有沿海-内陆的两极分布趋势。土壤总石油烃呈现代黄河三角洲内部低、外部高的趋势,靠近孤东油田的区域土壤中总石油烃含量相对较高。土壤剖面中铁氧化物和粘土矿物对重金属有显著富集,土壤粘粒也是表层和剖面土壤中γ-HCH的重要载体,土壤石油烃则主要与土壤发育程度相关。黄河泥沙的搬运和沉积是多数污染物的主要来源,但随着调水调沙、石油开采、农业垦殖和海岸工程等人类活动的日益频繁,黄河三角洲污染物逐渐受到了当地人为过程的影响。(3)黄河三角洲土壤剖面中稀土丰度与物源的风化程度和成土程度有正相关趋势。土壤剖面不同层次之间稀土分馏情况是同步的,轻稀土相对重稀土富集,La-Eu曲线较陡,Eu-Ld曲线较平缓,Eu呈较为明显的负异常,Ce正异常不明显。通过稀土特征参数可以得出,黄河三角洲各层次土壤的源物质在黄河侵蚀、搬运、沉积过程中经历了充分的混匀过程。(4)黄河三角洲土壤剖面中的典型红粘层主要分布在1855年之后形成的现代黄河三角洲和1855年之前形成的古代三角洲区域,在黄河和弥河之间为红粘层过渡区,在弥河以东无红粘层分布。出现深度较浅的红粘层沉积相对较厚。对典型剖面的137Cs和210Pb定年可得,黄河三角洲剖面红粘层沉积的年代在1910s~1960s区间内,红粘层多出现于沉积速率发生较为剧烈变化的层次区间,与水动力变化有关。在形貌特征上,典型红粘层平均粒径为6.69±0.79φ、中值粒径为11.6±7.3μm、红度(a*)值为7.5±0.4。(5)黄河三角洲土壤红粘层粘土矿物和方解石含量都显著高于其上下黄砂层,而原生矿物如石英和长石的含量则显著低于黄砂层。在常量元素组成上,典型红粘层SiO_2为55.6±3.7%、Al2O3为13.5±1.1%、CaO为8.18±1.03%、Fe2O3为5.49±0.83%、MgO为2.83±0.34%、K2O为2.54±0.83%和Na2O为1.34±0.32%。19种微量元素中,红粘层只有Zr和Hf含量显著低于黄砂层,其余微量元素都要显著高于黄砂层。红粘层相对黄砂层具有较高的风化程度,典型红粘层的硅铝率为6.71±1.06。磁学性质上,红粘层的磁学特征参数数值χfd%为8.3±1.7%、χarm为362.7±90.0×10-8 m3/kg、χarm/SIRM为67.1±15.1×10-5 m/A、SIRM/χlf为9.6±1.5×103 A/m和χARM/χlf为6.3±1.0,说明了红粘层中较细的成土性SP/SD颗粒含量较高,对该层磁性增强贡献较大。红粘层和黄砂层土壤胶体间色度和磁学特征差异较小,但粘土矿物和元素组成略有差异。黄河三角洲土壤红粘层是源区温湿气候条件下的高风化物质,经黄河由上游至下游搬运、混合、沉积,在三角洲地区水动力分选而形成。红粘层与黄砂层物源总体上较为相似,但又存在区别,主要是由于不同时期沉积造陆物源不同以及沉积时海相的影响和成陆之后的成壤过程导致不同土层间的地球化学特征差异。(6)黄河三角洲土壤红粘层重金属平均含量是黄砂层的约1.5倍,红粘层中铁锰结合易还原态Pb、Co以及弱酸溶态Cd比例要高于黄砂层,红粘层中重金属的潜在迁移性更强。红粘层是三角洲底层土壤中重要的有机碳、有机氮和无机碳库,红粘层中累积的无机碳可能主要以次生碳酸盐形式存在,具有固碳的能力。红粘层出现的深度和厚度结合黄河尾闾改道时间可推测现代三角洲形成期环境和人类活动变化。黄河三角洲土壤和沉积物的碳氮稳定性同位素分馏特征表明,滨海湿地土壤、菜地土壤、田地(棉田和粮田)土壤、河相沉积物、海湾和深海沉积物是影响区域碳氮循环的6组重要介质,由自然土壤向海洋沉积物过渡,对应了由源区较活跃有机质库向沉积区较稳定有机质库转移的过程。
[Abstract]:The the Yellow River delta is a region which is affected by human activities such as natural factors such as the flow of water and sediment in the Yellow River, the change of the end of the tail stream, the global climate change and other natural factors such as agricultural cultivation and maturation, urbanization, industrialization and other human activities. At present, the soil environment quality of the the Yellow River Delta region under the multiple effects of climate change, human activity and land sea interaction are affected by soil. This paper, based on 42 typical types of soil profiles (182 soil samples) and 26 adjacent sea surface sediments, analyzed the basic physical and chemical properties of soil, heavy metal elements and rare earth elements, organochlorine pesticides and organic chlorine pesticides in the the Yellow River Delta region. Organic pollutants such as petroleum hydrocarbons, mineral composition of soil and colloids, chemical composition, magnetic properties and other geochemical characteristics, soil and sediment radioactive lead isotopes and stable carbon, nitrogen isotopes, characterizing soil quality characteristics from land to sea in the the Yellow River Delta region, and exploring the soil of inorganic and organic pollutants. The geochemical behavior and source of the soil environment revealed the spatial and temporal distribution of the red sticky layer in the soil profile of the the Yellow River Delta, the geochemical characteristics and the environmental significance of the land sea interaction. These results can be used for the biogeochemical cycle and sustainable development of the the Yellow River Delta region under the high intensity human economic activity and strong land sea interaction. The main results of this study include the following aspects: (1) in the the Yellow River Delta, the soil salinity is gradually reduced and the soil structure and fertility level gradually decreases with the transition from sea to land in the tidal flat, wetland, cotton field, grain field and vegetable land. Among them, the soil structure of the beach is poor and the fertility level is very low, which represents the physical and chemical characteristics of the original soil under natural conditions in the area. After the tidal flat is developed into wetland, the environment of wetland flooding and the rich vegetation make the content of soil clay, organic matter, nitrogen, phosphorus and so on. Artificial improvement made soil desalination and alkali removal significantly, obviously improved soil nitrogen supply and phosphorus supply, but human activities intensified the destruction of soil aggregates and the release of organic matter. (2) the overall content of heavy metals, organochlorine pesticides and petroleum hydrocarbons in the the Yellow River delta is low, and the environmental ecological risk is not high at present. Soil heavy metals are in the the Yellow River river. The relative active components of organic chlorine pesticides (gamma -HCH and O, p '-DDT) and relatively stable components (beta -HCH and P, p' -DDE) have a coastal and inland two polar distribution trend. The total petroleum hydrocarbon in the soil is low in the modern the Yellow River Delta and in the external high, close to the total stone in the regional soil of the Gudong oilfield. The content of oil and hydrocarbon is relatively high. Iron oxides and clay minerals have significant enrichment in soil profiles. Soil clay particles are also important carriers of gamma -HCH in surface and section soils. Soil petroleum hydrocarbons are mainly related to the degree of soil development. The transport and deposition of sediment in the Yellow River are the main source of most of the pollutants, but with water regulation and sediment transfer, Human activities such as oil exploitation, agricultural reclamation and coastal engineering are increasingly frequent, and the pollutants in the the Yellow River delta are gradually affected by local human processes. (3) the abundance of rare earth in the soil profile of the the Yellow River Delta has a positive correlation with the degree of weathering and the degree of soil formation. The light rare-earth is relatively heavy rare earth, the La-Eu curve is steeper, the Eu-Ld curve is relatively gentle, the Eu has a more obvious negative anomaly, and the Ce anomaly is not obvious. Through the rare earth characteristic parameters, the source of soil in the the Yellow River Delta has experienced a full mixing process in the process of erosion, transport and deposition in the Yellow River. (4) the soil of the Yellow River Delta The typical red sticky layers in the section are mainly distributed in the modern the Yellow River delta formed after 1855 and the ancient Delta region formed before 1855, the transition zone between the red sticky layer between the Yellow River and the MI River, the distribution of the red sticky layer in the east of the river and the thicker sedimentary facies of the shallow red sticky layer. The 137Cs and 210Pb dating of the typical sections It is available that the red sticky layer in the the Yellow River delta section is in the 1910s~1960s interval, and the red sticky layer appears in the level interval of more severe changes in the deposition rate, which is related to the hydrodynamic changes. On the morphological features, the average particle size of the typical red sticky layer is 6.69 + 0.79 phi, the median particle size is 11.6 + 7.3 mu m, and the red degree (a*) value is 7.5 + 0.4. (5) (5). The content of clay minerals and calcite in the red clay layer of the delta is significantly higher than that of the upper and lower Yellow sand layers, while the content of primary minerals such as quartz and feldspar is significantly lower than that of the yellow sand layer. In the composition of the constant elements, the typical red sticky layer SiO_2 is 55.6 + 3.7%, Al2O3 is 13.5 + 1.1%, CaO is 8.18 + 1.03%, Fe2O3 is 5.49 + 0.83%, MgO is 2.83 + 0.34%, K2O is 2.54. The content of Zr and Hf in the red sticky layer is significantly lower than that of the yellow sand layer, and the other trace elements are significantly higher than the yellow sand layer. The red sticky layer has a higher weathering degree than the yellow sand layer. The silicon aluminum ratio of the typical red sticky layer is 6.71 + 1.06. magnetics, and the magnetic characteristic parameter value of the red sticky layer is fd% of the value Chi fd% for the red sticky layer. 8.3 + 1.7%, X arm is 362.7 + 90 x 10-8 m3/kg, X arm/SIRM is 67.1 + 15.1 * 10-5 m/A, SIRM/ LF is 9.6 + 1.5 * 103 A/m and X ARM/ x LF is 6.3 + 1. It shows that the thinner clay formation SP/SD particles in the red sticky layer are higher, and have greater contribution to the magnetic enhancement of this layer. The difference of chromaticity and magnetic characteristics between the red and yellow sand layer soil colloids is small. But there is a slight difference in the composition of clay minerals and elements. The red sticky layer of the soil in the the Yellow River delta is a highly weathered material under the warm and wet climate in the source area. It is transported, mixed and deposited from the upstream to the lower reaches of the Yellow River, and formed in the Delta region. The red sticky layer is similar to the yellow sand layer in general, but the difference is mainly due to the difference. (6) the average content of heavy metals in the red sticky layer of the the Yellow River delta is about 1.5 times that of the yellow sand layer, and the ratio of iron and manganese to the reductive Pb, Co and weak acid soluble Cd in the red sticky layer is higher than that in the red sticky layer. The potential mobility of heavy metals in the yellow sand layer is stronger in the red sticky layer. The red sticky layer is an important organic carbon, organic nitrogen and inorganic carbon pool in the bottom soil of the delta. The accumulated inorganic carbon in the red sticky layer may be mainly in the form of secondary carbonate and has the ability to carbon sequestration. The depth and thickness of the red sticky layer can be combined with the time of the the Yellow River tail end of the red sticky layer. The characteristics of carbon and nitrogen isotopic fractionation of soil and sediment in the Yellow River delta indicate that coastal wetland soil, vegetable soil soil, field (cotton field and grain field) soil, river facies sediments, bay and deep sea sediments are 6 important groups affecting regional carbon and nitrogen cycle, from natural soil. The transition from the soil to the marine sediment corresponds to the process of transferring the more active organic matter reservoir to the stable organic matter pool in the source area.

【学位授予单位】：中国科学院烟台海岸带研究所
【学位级别】：博士
【学位授予年份】：2016
【分类号】：S153;X53

【参考文献】