黄河三角洲滨海芦苇湿地磷的生物地球化学过程

	黄河三角洲滨海芦苇湿地磷的生物地球化学过程
	屈凡柱
学位类型	博士
导师	于君宝
	2014-05-16
学位授予单位	中国科学院研究生院
学位授予地点	北京
学位专业	环境科学
关键词	黄河三角洲滨海湿地芦苇磷生物地球化学过程
摘要	黄河三角洲滨海湿地是我国暖温带地区最年轻、最广阔的湿地生态系统，处在陆地-海洋相互作用最活跃的地带。保护区内芦苇集中分布面积达40万亩，区外大面积芦苇湿地被开垦成棉田，为响应退耕还湿工程，退耕芦苇湿地也大面积存在。湿地磷（P）的迁移转化过程不但影响着系统自身物质循环、能量流动和湿地生产过程，而且对湿地演化、物种分布以及生物多样性等产生深远影响。为了更好的了解滨海湿地中磷的迁移转化过程与驱动机制，本论文以滨海芦苇湿地（新生湿地和退耕湿地）为研究对象，通过野外观测和微区实验，研究了湿地土壤磷形态、分布与储量，湿地植物生物量与磷积累季节变化特征，湿地植物残体分解与分解过程磷动态变化特征，退耕还湿工程对湿地影响，建立了湿地系统磷循环分室模式。主要结论如下： 1）新生和退耕芦苇湿地研究样地内土壤（0-60 cm）TP平均含量分别为569.34 mg/kg和583.5 mg/kg；AP平均含量分别为6.12 mg/kg和5.74 mg/kg，P储量分别为0.433 kg/m²和0.437 kg/m²。采用Hedley磷分级方法测定的新生和退耕湿地土壤TP平均含量分别为624.2 mg/kg和649.2 mg/kg。二者TP_i总量之间差异不大，分别为545.1 mg/kg和542.4 mg/kg，分别占TP的87.33%和83.56%；D.HCl-P_i是土壤TP和TP_i的主要部分。TP_o分别为79.1 mg/kg和106.7 mg/kg，NaOH-P_o是土壤TP_o的主要部分。对各P组分与土壤基本理化性质做相关分析发现，P_i组分中Resin-P、Bicarb-P_i、OH-P_i和C.HCl-P_i的含量与TOC及金属元素的含量呈显著正相关关系，P_o组分与土壤基本理化性质相关性不显著。P_i是土壤磷的主要组成成分，退耕湿地TP_o含量明显高于新生湿地。 2）芦苇湿地土壤对外源P有很强的吸附能力，对P的固定能力不因为外源P含量的增加而发生较大变化；新生湿地对P的吸附能力强于退耕湿地。生长季内滨海芦苇湿地土壤（0-15 cm）P_o的净矿化量为7.49 g/m²，约占土壤TP_o储量（12.33 g/m²）的60.7%，新生滨海芦苇湿地土壤P_o的矿化速率随着土温升高而加快。 3）各器官中TP含量具有明显的季节变化规律。生长季内，二者地上各器官中（叶+茎）TP含量均呈波动性变化，但总体上呈递减趋势；根中TP含量呈波动变化；二者各器官中TP含量的变化与植物的生长节律相一致。二者对P的积累量均表现为：根 > 叶 > 茎，P主要在根中积累，根是P的重要储库。二者相比，退耕湿地芦苇当年P积累量高于新生湿地芦苇当年的积累量。 4）新生和退耕湿地芦苇群落凋落物P储量在11月份分别达到115.66 mg/m²和153.55 mg/m²，退耕湿地返还量大于新生湿地。两种湿地类型立枯物分解随时间变化总体趋势相同，即随着时间的延长失重率呈增大趋势；分解速率常数在0.001~0.002d^-1之间，新生和退耕湿地95%地上部分的分解时间分别为8.17 a和8.23 a；95%地下部分的分解时间分别为：3.69 a和3.71 a。芦苇枯落物的整个分解试验过程NAI值均小于100%，数据表明芦苇植物残体在分解过程中表现为 P 的净释放。 5）随补水频次的增加，规律性补水对生长季初期芦苇生物量有明显促进作用，但对芦苇植物器官中营养物质含量没有影响。施用氮肥在生长季可以明显提高芦苇植物叶和茎器官C和N的含量和根器官的C、N和P的含量，表明施用N肥对芦苇植物对P的吸收范围局限于根部。在施用一定量N肥的前提下，施用磷肥对芦苇植物体生物量和C、N和P等营养物质积累过程的促进作用微弱。 6）不同土地利用方式下，新生湿地、退耕湿地和棉田土壤C:N:P比值分别为42.6:1.6:1、71.2:2.0:1和63.2:1.9:1，土壤C:N:P比值没有严格限制在一定范围。土壤中N:P比值约为1.9:1，显著低于世界和中国平均水平，土壤处于缺氮状态。新生湿地、退耕湿地和棉田中植物C:N:P 比值分别为1753:22.4:1、1539:23.0:1和1196:23.8:1。虽然湿地植物的C:N:P比值也没有被严格限制在一定范围，但是植物N:P比值表现出较好约束值，在23左右。 7）建立了滨海芦苇湿地大气-土壤-植物系统的磷循环分室模式，确定了不同分室的磷储量以及分室间的磷流通量。大气降水中TP全年沉降量为72.88 mg/m²。土壤是湿地系统磷的主要储库,植物体地下部分是植物体库主要部分。新生和退耕湿地芦苇植物年吸收量分别为1.211 g P/m²和1.527 g P/m²；年返还量分别为0.792 g P/m²和1.119 g P/m²。退耕湿地循环系数和周转系数高于新生芦苇湿地，表明退耕湿地系统 P 的周转期较短，养分归还快，利用效率高。
其他摘要	The Yellow River Delta (YRD), located in the coastal zone with drastic land-ocean interaction, is the fastest growing delta in the world and the youngest wetland ecosystem in the warm temperate zone of China. Phragmites australis, also known as reed grass and a cosmopolitan plant found throughout the world, can survive in most wetland habitats with no exception of the YRD. Reed marsh covers about 26 000 ha of the reserve. Out of the reserve, most of Phragmites australis wetlands were reclaimed farmland which were mainly used to cultivate cotton plant; while part of cotton plant farmland were converted to reed grassland answer the policy of reverting cultivated land to wetlands. The biogeochemistry of phosphorus (P) not only affects the material cycle, energy flow and primary productivity of the wetlands, but also has significant effect on the evolution, species distribution and biodiversity of wetland. In order to understand the process and mechanism of phosphorus in coastal wetlands, in this thesis, two types of Phragmites australis wetlands which were newly formed wetland (NW) and farmland converted into wetland (FW) in YRD were selected as research objects, field observation and micro-plot experiment were carried out from April 2012 to September 2013 to study the forms and storage, profile distributions and storage of phosphorus in reed-dominated wetland soils, the seasonal dynamics of plant biomass and phosphorus accumulation, litter decomposition rules and phosphorus dynamics in the decomposition process, the impact of grain for green project on wetland; then, the phosphorus biological cycling compartment model of air-soil-plant system was established. The main results were as following: 1) The mean contents of TP, AP in NW and FW (0-60 cm) were 569.34 mg/kg, 6.12 mg/kg and 583.5 mg/kg, 5.74 mg/kg respectively, and the storage of P in NW and FW (0-60 cm) were 0.433 kg/m²and 0.437 kg/m² respectively. The mean contents of TP extracted by P fractionation procedure developed by Hedley were 624.2 mg/kg, 649.2 mg/kg respectively, in which inorganic P (P_i) were 545.1 mg/kg and 542.4 mg/kg and organic P (P_o) were 79.1 mg/kg and 106.7 mg/kg respectively. Dilute HCl extractable P_iwas the predominant form in all profiles, both as absolute values and as a percentage of total extracted P_i, and NaOH extractable P_o was the predominant form of total extracted P_o. The Pearson correlation matrix indicated that Resin-P, Bicarb-P_i, NaOH-P_i and C.HCl-P_iwere strongly positive correlated with salinity, TOC, Ca, Al and Fe, but negatively correlated with pH. The significant correlation of any studied forms of organic P (Bicarb-P_o, and NaOH-P_o and C.HCl-P_o) with geochemical properties were not observed in the study. The difference in P_o in NW and FW could be attributed to the influences of anthropogenic cultivation. 2) The reed-dominated wetland soils had strong capacity to adsorb P, and the amount of P fixation did not change greatly with outside input. The P adsorption capacity in NW soils was stronger than FW, and both of them paly roles as P sink. net P mineralization in NW soil (0-15 cm) was about 7.49 g/m² in the growth season which accounted for 60.7% of total soil P_o (12.33 g/m²), and P mineralization rate increased with the soil temperature. 3) The total phosphorus content in different organs of Phragmites australis had seasonal changes. The total phosphorus content in aboveground organs of Phragmites australis were fluctuant, but declined as a whole in the grown season. The total phosphorus content in roots was different. Phosphorus accumulation amounts in two types Phragmites australis wetland were both root > leaf > stem in growth season, which indicated root was the important phosphorus storage, comparatively phosphorus accumulation amounts in NW were much higher than those in FW. 4) Until November, the P accumulation in litters in NW and FW was 115.66 mg/m²and 153.55 mg/m² respectively. FW returned more P than NW. Litter decomposition of the two types of wetlands had a same trend and the weight loss rate decreased with time. Decomposition rate ranged from 0.001 to 0.002d^-1, influenced by the temperature, and it decreased with time as well. The time of 95% decomposition process of aboveground and underground part of reed in NW and FW was 8.17 a, 8.23 a and 3.69 a, 3.71 a respectively. NAI index indicated that there was P release during decomposition. 5) With the increase of frequency of regular water-replenishment, water had an obvious promoting effect on the reed biomass production, but did not increase the nutrient content of organs of reed plants. N fertilizer treatments supplied with 150 kg N/hm²could obviously improve the C and N content in leaf and stem and the C, N and P content in root of reed during the growing season. The results showed that N fertilizer only increased P adsorption confined to root organs. Under the same fertilized treatments supplied with same amount N, there were no obvious difference in element concentrations in crop and crop production with a range of P fertilizer. 6) Land-use change had significant effects on the distribution of soil and plant C, N and P stoichiometry in reed-dominated coastal wetlands. Our results showed R_CNP in both the soil (42.6:1.6:1(NW), 71.2:2.0:1(FW), and 63.2:1.9:1(CW), respectively) and the plant (1753:22.4:1(NW), 1539:23.0:1(FW), and 1196:23.8:1(CW), respectively) were not well-constrained, while an average atomic N:P ratio in both the soil (~1.9:1) and the plant (~23:1) are well-constrained. Element ratios of soil and plant potentially provide insights into N limitation in coastal wetland ecosystems. 7) The compartment model on the distribution and circulation of phosphorus in atmosphere-soil-plant system of Phragmites australis wetland ecosystem was established. The model showed that the input of P in annual precipitation to Phragmites australis wetland ecosystem was 72.88 mg/m²·a. The soil was the most important P pool in the system. Underground compartment of the plant is the main part of the plant compartment. The uptake flux of plant in NW and FW was 0.792 g P/m²·a and 1.119 g P/m²·a respectively, while the return flux was 0.792 g P/m²·a and 1.119 g P/m²·a respectively. The circulation and turnover coefficients in FW were higher than those in NW, which implied that the P turnover period in FW was short and with high utilization efficiency.
语种	中文
文献类型	学位论文
条目标识符	http://ir.yic.ac.cn/handle/133337/6806
专题	中国科学院烟台海岸带研究所知识产出_学位论文
推荐引用方式 GB/T 7714	屈凡柱. 黄河三角洲滨海芦苇湿地磷的生物地球化学过程[D]. 北京. 中国科学院研究生院,2014.

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