河口红树林湿地CH_4通量的日变化研究

１引言 甲烷（ＣＨ４）是大气中除 ＣＯ２外最为丰富的含碳组分,其浓度以每年 ０． ７％－ １． １％的速率递增［１,２］．尽管大气 ＣＨ４含量仅为 ＣＯ２的二百分之一,但却对预计的全球变暖约有 ２０％的贡献率,而ＣＯ２的贡献率约为５０％［３,４］,由这些数据推算得一个分子的ＣＨ４比一个分子的ＣＯ２（目前最重要的温室气体）的增暖潜值高约８０倍． 很多研究者对全球大气ＣＨ４的预算结果均表明,湿地是大气 ＣＨ４最重要的生物源［５,６］,约占全球 ＣＨ４源的 ４０％～５０％［７］．湿地 ＣＨ４通量的日变化研究是正确估…     

海南长宁河口桐花树红树林土壤CH4动态研究

研究了海南东寨港长宁河口桐花树Aegzceras corniculatum红树林下土壤的CH4动态.土壤CH4通量的滩面变化规律四季一致,平均值为0.56 mg     

海南海莲红树林土壤CH4的产生及其某些影响因素

全球CH₄预算的估算表明,湿地是大气CH₄最大的生物排放源[1].旨在估算全球大气CH₄湿地源强的工作大多集中在内陆淡水环境,因为在此环境的CH₄通量较大[2].国外对海岸盐沼的CH₄排放也有一些报道,发现其通量变化范围较大,并进而研究了温度、土壤湿度、盐度以及土壤有机碳含量等因素对CH₄排放的影响[3].     

苏北滨海湿地互花米草潮滩CO2,CH4和N2O通量的日变化规律

The invasions of the alien species such as Spartina alterniflora along the northern Jiangsu coastlines have posed a threat to biodiversity and the ecosystem function.Yet,limited attention has been given to their potential influence on greenhouse gas(GHG) emissions,including the diurnal variations of GHG fluxes that are fundamental in estimating the carbon and nitrogen budget.In this study,we examined the diurnal variation in fluxes of carbon dioxide(CO_2),methane(CH_4),and nitrous oxide(N2O) from a S.alterniflora intertidal flat in June,October,and December of 2013 and April of 2014 representing the summer,autumn,winter,and spring seasons,respectively.We found that the average CH_4 fluxes on the diurnal scale were positive during the growing season while negative otherwise.The tidal flat of S.alterniflora acted as a source of CH_4 in summer(June) and a combination of source and sink in other seasons.We observed higher diurnal variations in the CO_2 and N_2O fluxes during the growing season(1 536.5 mg CO_2 m~(–2) h~(–1) and 25.6 μg N_2O m~(–2) h~(–1)) compared with those measured in the non-growing season(379.1 mg CO_2 m~(–2) h~(–1) and 16.5 μg N_2O m~(–2) h~(–1)).The mean fluxes of CH_4 were higher at night than that in the daytime during all the seasons but October.The diurnal variation in the fluxes of CO_2 in June and N_2O in December fluctuated more than that in October and April.However,two peak curves in October and April were observed for the diurnal changes in CO_2 and N_2O fluxes(prominent peaks were found in the morning of October and in the afternoon of April,respectively).The highest diurnal variation in the N_2O fluxes took place at 15:00(86.4 μg N_2O m~(–2) h~(–1)) in June with an unimodal distribution.Water logging in October increased the emission of CO_2(especially at nighttime),yet decreased N_2O and CH_4 emissions to a different degree on the daily scale because of the restrained diffusion rates of the gases.The seasonal and diurnal variations of CH_4 and CO_2 fluxes did not correlate to the air and soil temperatures,whereas the seasonal and diurnal variation of the fluxes of N_2O in June exhibited a significant correlation with air temperature.When N_2O and CH_4 fluxes were converted to CO_2-e equivalents,the emissions of N_2O had a remarkable potential to impact the global warming.The mean daily flux(MF) and total daily flux(TDF) were higher in the growing season,nevertheless,the MF and TDF of CO_2 were higher in October and those of CH_4 and N_2O were higher in June.In spite of the difference in the optimal sampling times throughout the observation period,our results obtained have implications for sampling and scaling strategies in estimating the GHG fluxes in coastal saline wetlands.     

渤海溶解CH4分布和通量的季节变化及其影响因素

甲烷(CH₄)是影响地球辐射平衡的主要温室气体,海洋是大气CH₄的自然源,而陆架等近海是释放CH₄的热点海域。于2021年4月、7月和10月对渤海进行了调查,以认识其分布特征并估算其海-气交换通量。春、夏和秋季表层海水CH₄浓度分别为(4.56±2.60)、(8.31±4.01)和(4.99±1.31) nmol/L,夏季明显高于春秋季。CH₄的垂直分布规律为底层普遍高于表层,不同站位的垂直分布空间差异较大。渤海CH₄分布主要受河流输入、油气泄漏、生物活动以及沉积物-水界面交换等因素的影响,其中黄河向渤海输入CH₄约为每月1.4×104～2.8×105mol,秋冬季沉积物-水界面CH₄交换通量范围为–4.0～0.42μmol/(m²·d),表明秋冬季沉积物既可能是渤海水体CH₄的源,也可能是其汇。春、夏和秋季渤海CH₄海-气交换通量分别为(1.1±...     

珠江口淇澳岛湿地甲烷排放通量及日变化规律

2009年8月份采用静态箱法对珠江口淇澳岛湿地甲烷通量日变化进行测定,结果表明甲烷排放通量在当日23:00和翌日早晨9:00出现两个高峰值,分别为40.07和50.99 mg·m-2·h-1;在当日17:00和翌日凌晨5:00出现两极小值,分别为1.13和1.57 mg·m-2·h-1,同步观测孔隙水中SO42-、Cl-浓度和沉积物表层温度和采样点潮位变化,发现湿地甲烷排放通量与孔隙水中SO42-浓度和潮位存在显著负相关性,因此,潮汐所导致孔隙水中SO42-浓度和上覆水深度改变,可能是控制珠江口淇澳岛潮间带湿地甲烷日排放通量变化的两个关键因素。同时计算采样点甲烷日排放净通量达到962.7 mg·m-2·d-1,表明夏季珠江口淇澳岛湿地是大气甲烷的源区。柱状沉积物孔隙水中甲烷浓度范围为0.52~5.18 mmol·dm-3,其最大值出现在9 cm深度,同时测试沉积物中总有机碳(TOC)、温度、氧化还原电位和孔隙水中SO42-的浓度,结果表明高的甲烷浓度主要是由于沉积物中高的TOC含量和孔隙水中低的SO42-浓度所导致。     

西太平洋雅浦海沟区海水中CH4和DMSP的垂直变化特征

本研究首次探究了西太平洋雅浦海沟北段从表层到超深渊海水中甲烷（CH₄）及二甲基硫（DMS）的前体物质二甲基巯基丙酸内盐（DMSP）的浓度变化情况。结果表明:雅浦海沟海水甲烷浓度变化范围为1.49~3.87 nmol/L。其上层海水甲烷平均浓度最高,有明显的次表层极大现象。雅浦海沟氧最小层海水的甲烷平均浓度最低;在500~1 000 m中层水中甲烷浓度有一定程度的增大,1 000 m以下至底层甲烷浓度继续升高。研究海区溶解态DMSP（DMSPd）和总DMSP（DMSPt）平均浓度的垂直变化随深度呈先增大后减小趋势,颗粒态DMSP（DMSPp）的平均浓度随深度呈波动式变化,在中层达到最大。雅浦海沟CH₄和DMSP浓度垂直变化受浮游生物、微生物、光照、温度、压力、大洋环流等的复杂影响。在真光层海水中,CH₄浓度与DMSPd、DMSPp和DMSPt浓度表现为负相关关系,在200 m至底层海水中,CH₄浓度与DMSPd、DMSPp和DMSPt浓度表现为正相关关系,显示光照条件是造成雅浦海沟不同深度海水CH₄和DMSP浓度相关性差异的关键因素。     

红树林人工湿地硝化和反硝化作用研究

以占地近400 m2的红树林人工湿地中试系统为研究对象,阐述了人工湿地表层基质(0～5 cm)中硝化和反硝化作用在不同植物、不同水平距离问的分布变化规律.结果表明,红树林人工湿地可同时进行硝化和反硝化作用.桐花树湿地带的硝化和反硝化作用强度显著高于其它两种红树植物湿地带(P<0.05);硝化作用和反硝化作用强度均是随着水流方向减少(海桑带除外).相关性分析表明,硝化/反硝化作用强度与盐度和电导率呈显著正相关(P<0.05),与有机质、硝化/反硝化茵数量呈不显著正相关(P>0.05).     

海南红树林湿地沉积物中重金属的累积

于2008年在海南典型红树林湿地东寨港、三亚湾和亚龙湾采集沉积物样品,使用原子吸收分光光度法(SOLAAR M6)分析沉积物中Cu、Pb、Zn、Cd和Cr的含量,原子荧光光度法(AFS-8130)分析Hg和As的含量.表层沉积物中Cu、Pb、Zn、Cd、Cr、Hg和As的平均含量分别为14.8±9.2、24.1±9.2、57.9±36.5、0.17±0.10、29.6±20.4、0.08±0.04和9.7±4.4μg·g-1干重(DW),目标化合物(除Cd外)的含量均具有东寨港高、三亚湾次之而亚龙湾低的特点,Cd的含量各区域相近.与国内外其他典型红树林沉积物中重金属的含量相比,本研究区域沉积物重金属含量处于中偏低的水平,这与海南目前开发程度较低、人类活动影响较小相一致.柱状沉积物中Cu、Pb、Zn、Cd、Cr和Hg含量的剖面分布均具有表层稍低、中上层较高和底层相对低的特征,而As的含量呈现表层较高、中上层低和底层相对高的特点.潜在风险分析显示,本研究区域沉积物中重金属(As除外)目前污染较轻,对生态环境影响较小.     

红树林湿地沉积物中海洋线虫个体干质量的研究

对采自2012-2013年4个季度,福建九龙江口和洛阳江口红树林湿地沉积物中的海洋线虫进行了分选和制片,对其优势属的全部个体进行了体长和体宽的测量。利用体积换算法,获得了线虫群落成体干质量变化情况。结果表明:红树林湿地沉积物中海洋线虫群落优势属个体成体干质量在0.14~4.88 μg之间,幼体的变化范围在0.17~1.46 μg之间,平均的个体干质量为0.826 μg。海洋线虫群落结构种类组成和幼体所占比例是影响线虫个体干质量估算的主要因素。建议对红树林湿地沉积物中海洋线虫生物量的估计当以实测为最佳,如采用经验系数则建议使用个体平均干质量0.8 μg。     

The state of legislation and policy protecting Australia's mangrove and salt marsh and their ecosystem services

Saline coastal wetlands, such as mangrove and coastal salt marsh, provide many ecosystem services. In Australia, large areas have been lost since European colonization, particularly as a result of drainage, infilling and flood-mitigation works, often starting in the mid-19th century and aimed primarily towards converting land to agricultural, urban or industrial uses. These threats remain ongoing, and will be exacerbated by rapid population growth and climate change in the 21st century. Establishing the effect of wetland loss on the delivery of ecosystem services is confounded by the absence of a nationally consistent approach to mapping wetlands and defining the boundaries of different types of coastal wetland. In addition, climate change and its projected effect on mangrove and salt marsh distribution and ecosystem services is poorly, if at all, acknowledged in existing legislation and policy. Intensifying climate change means that there is little time to be complacent; indeed, there is an urgent need for proper valuation of ecosystem services and explicit recognition of ecosystem services within policy and legislation. Seven actions are identified that could improve protection of coastal wetlands and the ecosystem services they provide, including benchmarking and improving coastal wetland extent and health, reducing complexity and inconsistency in governance arrangements, and facilitating wetland adaptation and ecosystem service delivery using a range of relevant mechanisms. Actions that build upon the momentum to mitigate climate change by sequestering carbon – ‘blue carbon’ – could achieve multiple desirable objectives, including climate-change mitigation and adaptation, floodplain rehabilitation and habitat protection.     

东海2012年夏季海-气界面碳交换及其区域碳汇强度变化趋势初探

基于2012年7月对东海的调查,剖析了其水体中各形态碳(pCO2、DIC、DOC、POC)的区域分布特征,估算了海-气界面CO2的交换通量(FCO2),探讨了影响其交换的主要因素,在此基础上,结合历史资料初步分析了近十几年来该海域海-气界面CO2交换通量的变化趋势。结果表明,2012年7月长江口邻近海域相对南部陆架区具有较低的DIC浓度,而DOC与POC的浓度相对较高。调查区域表层水pCO2变化范围为96.28~577.7μatm(1atm为101 325Pa),平均值为297.6μatm,低值区出现在长江冲淡水区(30°~33°N,123°~125°E),高值区主要分布在东海陆架的南部区域。表层水pCO2主要受控于长江冲淡水的输入和混合(盐度)、台湾暖流以及生物生产等。调查海域2012年7月海-气FCO2平均为(-6.410±7.486)mmol/(m2·d),表现东海在夏季是大气CO2的汇区,区域碳汇强度由强到弱依次为:长江冲淡水区(CDW)、黄东海混合水区(YEMW)、陆架咸淡水混合区(SMW)、近岸上升流区(CUW)和台湾暖流区(TWCW),东海夏季每日吸收大气CO2(以C计)约(18.3±19.8)kt。结合历史资料分析发现,近十几年来东海夏季碳汇强度有增强趋势,CDW区的海-气界面CO2通量平均年增速为-0.814mmol/(m2·d),即海水吸收大气二氧化碳每年增加约54.6kt,是夏季东海碳汇增加的最主要贡献者。     

Dissolved inorganic carbon and CO2 fluxes across Jiaozhou Bay air-water interface

On the basis of data collected in the Jiaozhou Bay in June and July 2003, the DIC distribution in seawater is studied,and an average air-sea flux of CO2 is estimated. The results show that the content of DIC inside the bay is markedly higher than outside the bay in June, but the contem of DIC outside the bay is markedly higher than inside the bay in July. The trend of DIC distribution inside the bay is similar, viz. the content is the maximum in the northeast, then decreases gradually toward the west, and the content is the minimum in the west. The total trend of vertical distribution is to increase gradually from surface to bottom. This characteristic of DIC distribution is determined by Jiaozhou Bay hydrology and there is a close relation between DIC and particulate N.P. Average CO2 flux across the air-sea interface is 0.55 mol/(m^2.a) in June and 0.72 mol/(m^2.a) in July. Jiaozhou Bay is considered as a net annual source for atmospheric CO2 in June and July, and the total CO2 flux from seawater into atmosphere is about 740 t in June and 969 t in July.     

夏季九龙江口红树林土壤-大气界面温室气体通量的研究

红树林湿地土壤是一个潜在的温室气体排放源.调查了夏季福建九龙江口的秋茄（Kandelia candel）红树林湿地土壤-大气界面3种温室气体的通量并分析土壤环境对其的影响.研究结果显示,九龙江口红树林夏季3种温室气体N2O、CH4和CO2的通量分别是0.27～2.45、-0.28～341.43μmol/（m2·h）和-0.49～17.00 mmol/（m2·h）,表明九龙江口夏季红树林土壤总体上是温室气体的排放源.根据3种温室气体的平均通量及其增温潜力计算它们的CO2当量通量以反映3种温室气体产生的增温效应,计算结果显示九龙江口红树林夏季土壤排放温室气体的CO2当量通量为82.33～674.92 mg/（m2·h）,而CO2是最大的贡献因素.双因素方差分析结果表明,CO2通量和土壤理化性质因林地和滩面而异,CH4通量受林地的影响,但N2O通量则不受林地和滩面的影响.相关性分析结果显示,土壤环境因子是影响红树林温室气体通量空间差异的重要原因,其中土壤有机质、氨态氮和总氮含量是影响N2O和CO2通量的主要因子,而CH4则只与土壤氧化还原电位显著相关.     

利用TOPEX/Poseidon高度计资料提取的太平洋M2内潮能通量分布

基于内波动力学方程,提出利用TOPEX/Poseidon高度计资料提取内潮的方法.利用该方法,结合1992年10月到2002年6月共10a的TOPEX/Poseidon高度计资料和Levitus(1998)资料,给出了整个太平洋M₂内潮能通量的分布,并与观测资料进行比测,两者符合较好.同时也发现沿整个太平洋边界M₂内潮能通量向大洋内部输入的总功率为58.4GW,其中北太平洋对此贡献为30.2GW,南太平洋为28.2GW,可见南、北太平洋的贡献是基本相等的.东太平洋的总量为17.8GW,而西太平洋为40.6GW,两者差异较大(以160°W作为东、西太平洋分界线).     

中国滨海湿地互花米草群落甲烷通量研究的综述

互花米草(Spartina alterniflora)具有较强的固碳作用,了解互花米草群落的甲烷通量可为评估互花米草的净碳汇功能提供重要参数。本文分析了我国滨海湿地互花米草群落CH₄通量的总体特点和机制,结果表明：①不同地区互花米草群落CH₄通量无明显规律且差异较大。不同生长环境下的环境因子对CH₄排放有综合调控作用,其中很大部分是通过影响土壤中与CH₄产生有关的微生物影响CH₄通量。②互花米草群落CH₄通量夏季最高、冬春较低;日通量则处于不规则的波动中,但总体白天通量高于夜晚。CH₄通量季节差异与温度、生物量和光照呈正相关,温度影响参与CH₄生成的微生物的活性,生物量为CH₄产生提供有机质原料,光照则通过光合作用影响有机质的合成;日通量差异除与温度和光照有关外,最主要还受到潮汐变化的影响。③无潮水覆盖时CH₄通量远大于有潮水覆盖时。有潮水覆盖时互花米草下部作为CH₄排向大气的重要通道受阻,同时CH₄被储存于土壤或排放到潮水中,落潮后才进入大气,因此CH₄通量更低。④刈割会降低CH₄通量。互花米草植株为CH₄的产生提供了重要原料,同时利用通气组织将CH₄排放到大气,刈割切断了CH₄传输途径并减少了地上生物量,因此降低了CH₄通量。     

Distributions and air-sea fluxes of CO2 in the summer Bering Sea

The 3rd Chinese National Arctic Research Expedition(CHINARE–Arctic III) was carried out from July to September in 2008. The partial pressure of CO2(pCO2) in the atmosphere and in surface seawater were determined in the Bering Sea during July 11–27, 2008, and a large number of seawater samples were taken for total alkalinity(TA) and total dissolved inorganic carbon(DIC) analysis. The distributions of CO2 parameters in the Bering Sea and their controlling factors were discussed. The pCO2 values in surface seawater presented a drastic variation from 148 to 563 μatm(1 μatm = 1.013 25×10-1 Pa). The lowest pCO2 values were observed near the Bering Sea shelf break while the highest pCO2 existed at the western Bering Strait. The Bering Sea generally acts as a net sink for atmospheric CO2 in summer. The air-sea CO2 fluxes in the Bering Sea shelf, slope, and basin were estimated at-9.4,-16.3, and-5.1 mmol/(m2·d), respectively. The annual uptake of CO2 was about 34 Tg C in the Bering Sea.     

Experimental formation of massive hydrate deposits from accumulation of CH4 gas bubbles within synthetic and natural sediments

In order for methane to be economically produced from the seafloor, prediction and detection of massive hydrate deposits will be necessary. In many cases, hydrate samples recovered from seafloor sediments appear as veins or nodules, suggesting that there are strong geologic controls on where hydrate is likely to accumulate. Experiments have been conducted examining massive hydrate accumulation from methane gas bubbles within natural and synthetic sediments in a large volume pressure vessel through temperature and pressure data, as well as visual observations. Observations of hydrate growth suggest that accumulation of gas bubbles within void spaces and at sediment interfaces likely results in the formation of massive hydrate deposits. Methane hydrate was first observed as a thin film forming at the gas/water interface of methane bubbles trapped within sediment void spaces. As bubbles accumulated, massive hydrate growth occurred. These experiments suggest that in systems containing free methane gas, bubble pathways and accumulation points likely control the location and habit of massive hydrate deposits.     

Cr4+ :Ca2 GeO4激光晶体生长及结构表征

采用助熔剂法,以CaCl₂为助熔剂,生长Cr⁴⁺ :Ca₂GeO₄新型近红外可调谐激光晶体.通过X射线衍射(XRD)、激光Raman光谱、X射线光电子能谱(XPS)等方法对晶体进行结构表征.结果表明,得到的晶体为单斜晶系镁橄榄石结构的低温γ-Cr⁴⁺ :Ca₂GeO₄单晶,晶格参数为a=5.3209 (1 =0.1 nm)