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1.
中国主要红树林湿地沉积物中硫的分布特征及影响因素   总被引：6，自引：0，他引：6  
以中国红树林主要分布地区--海南、广东、广西、福建的13个红树林区为研究对象,对沉积物中硫的分布特征及相关影响因素进行了分析.中国红树林地区沉积物中硫含量为0.009%～0.809%,平均含量为0.214%,远高于非红树林生长地区沉积物中硫的平均含量.海南、广东、广西、福建四省区红树林沉积物中硫的平均含量分别为:0.34%、0.19%、0.20%、0.18%.13个地区含硫量高低顺序为:三亚、东寨港、云霄、钦州、俄湾、姚家屿、高桥、山口、大冠沙、北仑河口、福田、洛阳桥、浮宫.各个不同红树林地区沉积物中的硫含量差异显著.硫含量与有机质含量、盐度显著正相关,与pH值显著负相关.土壤粒度组成以及铁含量对土壤中全硫含量有一定的影响.  相似文献   

2.
潮滩作为重要的湿地类型和高效的有机碳汇备受关注,近期围垦、养殖等人类活动和互花米草入侵对潮滩生化环境和有机碳埋藏产生了重要影响。本研究选取了福建三沙湾三处不同植被类型的潮滩各取得沉积物短柱样,测定沉积物的总有机碳含量(TOC)、稳定碳同位素(δ13C),结合210Pbex测试计算的沉积速率,估算了不同区域的有机碳埋藏通量(BC)。结果表明,互花米草阶段和红树林阶段TOC含量分别为0.67%和0.95%,比对应的光滩阶段分别提高了13.6%和26.7%,表明红树林对潮滩固碳效率的提升比互花米草更加显著。在两者的共同生长区域,随时间推移TOC含量显著下降,表明互花米草入侵挤占红树林生长空间之后,降低了潮滩的固碳效率。短柱样沉积物δ13C值分布范围在-24.70~-21.87‰,主要体现海源有机质同位素特征,但也会受潮滩植被生长类型影响。对各短柱样有机碳埋藏通量进行估算,得到研究区红树林生长阶段BC平均值为149.53 g/m2/yr,远高于互花米草生长阶段的平均值57.37 g/m2/yr。  相似文献   

3.
应用分形理论分析了防城港湾红树林表层沉积物粒径分布及其分形特征,并分析了pH值、C有机质、C硫化物、CTN、CTP、CK、水溶性盐分等环境因子.沉积物由海向陆的砂含量减少,细砾、粉砂和粘土含量增多,平均粒径也呈渐次增大.沉积物分选性都是差到很差,偏态都是正偏态到很正偏态,峰态都是中等尖锐到很尖锐.沉积物各粒径含量与pH值、有机质、硫化物含量相关关系不明显,砂、粉砂含量与CTN、CTP、CK呈显著相关关系.沉积物的分形维数为2.322 1～2.649 1,分维值与环境因子相关关系不明显,与粘土含量呈显著正相关(R=0.978,p＜0.01).沉积物分形值呈含砾砂(2.322 1)＜含砾泥质砂(2.513 0～2.618 1)＜含砾泥(2.649 1)的趋势.不同滩位的红树林沉积物分形维数呈现向海侧红树林外光滩(2.322 1～2.5602)＜向海侧红树林林带(2.513 0～2.5909)＜红树林林带中心(2.557 0～2.595 6)＜向陆侧红树林带(2.618 1～2.649 1)的规律.沉积物类型、粘土组分、滩位等是影响防城港湾红树林沉积物分形维数的主要环境因子.  相似文献   

4.
气候变化和人类活动制约下的红树林演变是一种长时间尺度效应,而沉积物则是记录这种响应的最佳档案。采用古生态学研究思路,选择有效的示踪参数是解读这一档案的有效途径。本文通过广西钦州湾红树林区1根柱状沉积物中有机碳同位素(δ13C)、C/N分析和孢粉鉴定,以沉积物中的红树林源有机碳贡献和红树植物孢粉组合为示踪参数,在210Pb年龄框架构建的基础上,通过对比研究红树林源有机碳贡献和红树孢粉组合特征,揭示百年来钦州湾红树林兴衰和群落演替规律;进而重塑其红树林演变历史:兴盛期(1864-1918年)、衰退期(1918-1968年)和低谷期(1968-2007年),这与土地替代、遥感分析和现场勘测数据较为吻合。结合气候变化和人类活动资料,发现钦州湾红树林的近期衰退主要源于人类活动的影响,尤其是虾塘围垦;而与气候变化关系不大。  相似文献   

5.
随着工业化进程的加快,湛江湾的生态环境承载力受到了极大的考验。为了解湛江湾生态环境的变化过程,文中利用湛江湾表层柱状沉积物样品中总有机碳含量(TOC)及其稳定同位素、总氮含量(TN)和C/N值的测定,结合端元混合模型,分析了湛江湾沉积物中有机质的来源,探讨了沉积物有机碳同位素的主要影响因素。结果表明,湛江湾沉积物中有机质主要来源为自生藻类,同时也受一定程度陆源输入的影响。沉积序列的元素地球化学参数表明,沉积物δ13C值呈现短暂的负偏随后长期正偏的趋势。底部的负偏可能与大气CO2浓度增加有关,随后δ13C主体正偏的趋势主要受控于气候转暖、生产力增加以及富营养化程度增加的共同影响,暗示了人类活动对湛江湾的生态环境的影响逐渐加剧。其中,人类活动相关的工业、农业有机污染物排放可能是不断加剧海水富营养化的主要原因。  相似文献   

6.
对海南岛红树林柱样中有机生物标志物等生物地球化学参数进行了初步研究.结果显示红树林中有机碳(OC)与总氮(TN)比值范围为5.35-7.47,碳稳定同位素(δ13C)值范围为-25‰--22.9‰.脂肪酸与正构烷烃浓度分布范围分别为7.8-21.8μg·g-1(干重)和3.2-25μg·g-1(干重).在表层沉积物中,红树林植物、细菌与浮游生物的脂肪酸生物标志物各占总脂肪酸的25.4%、12.9%和7.5%,结合较低的OC/TN比值和较高的δ13C值,表征了当地微生物和外源浮游植物的有机质贡献.各类脂肪酸在柱样中表现出不同的降解特征:多不饱和脂肪酸(PUFAs)优先被降解,而长链脂肪酸(LCFAs)则较为稳定,没有明显的降解.碳优势指数(CPI)和平均碳链长度(ACL)显示,埋藏深度越深,有机物的生物化学改造程度越大.  相似文献   

7.
对青海湖沉积物中粒度参数、总有机碳（TOC）含量及其δ^13C值的形成条件与环境气候的关系进行了研究。结果表明：在暖湿时期，沉积物中有机碳含量（TOC）较高，有机质的δ^13C值较高，沉积物的平均粒径较细；反之，在冷干时期，沉积物中有机碳含量（TOC）较低，有机质的δ^13C值较低，沉积物的平均粒径较粗。反映出沉积物中TOC含量、有机质δ^13C值及粒度特征与气温具有良好的相关性。结合^14C测年，分析了湖区古气候演化序列，表明自8500aBP以来湖区气候经历了4个演化阶段：即暖湿－凉干－温湿－冷干的变化过程。  相似文献   

8.
广东省典型海湾表层沉积有机质的来源和分布   总被引：1，自引：0，他引：1  
于2009年对广东省3个典型海湾湛江港、深圳湾和流沙湾表层沉积物的稳定碳同位素进行了分析。结果显示,湛江港表层沉积物δ13C值的范围为25.9‰—23.9‰,平均值为25.2‰;深圳湾表层沉积物的δ13C值的范围为25.9‰—23.2‰,平均值为25.1‰;流沙湾表层沉积物的δ13C值的范围为23.2‰—20.0‰,平均值为20.9‰。根据经典二元模式计算,湛江港陆源有机质的贡献比例范围为0.57—0.90,平均为0.78;深圳湾陆源有机质的贡献比例范围为0.45—0.90,平均为0.76;而流沙湾表层沉积有机质中海洋有机质的贡献比例较大,陆源有机质的贡献比例很小。湛江港和深圳湾表层沉积有机质主要来源于陆架,可能是C3(光合作用最初产物为三碳化合物)植物和海洋浮游微藻的混合有机质,但起主导作用的是陆架C3植物;而流沙湾表层沉积有机质主要来源于大型海藻和贝类的排泄物。各海湾沉积有机质的分布没有明显的规律性,主要受大陆径流、航运和潮汐的影响,同时也受海域初级生产力和水产养殖业的影响。  相似文献   

9.
基于对胶州湾表层沉积物中总可水解氨基酸（THAA）的含量、组成、构型及分布特征的系统研究,通过氨基酸碳氮归一化产率（THAA-C%,THAA-N%）、降解因子DI、反应活性指数RI以及D型氨基酸占比（D-AA%,摩尔百分比）等指标结合碳氮比（TOC/TN）、碳稳定同位素（δ13C）探析了胶州湾沉积物中有机质的来源与降解状态,利用细菌源有机质及胞外肽酶活性（EEA）探讨了微生物在有机质迁移转化过程中的作用与贡献。结果表明,胶州湾表层沉积物中氨基酸平均含量为（7.60±3.64）μmol/g,在陆源与海源混合影响下,其水平分布呈现湾内高于湾外、湾内东部高于西部的特点,表明湾内东部陆源输入对沉积物THAA具有较高贡献。THAA-C%、THAA-N%、DI、RI以及D-AA%等指示因子均显示胶州湾表层沉积物中有机质的降解程度呈现湾外高于湾内、湾内东部高于西部的变化趋势,有机质来源、微生物活性与上覆水水深共同影响了有机质的降解程度。胶州湾表层沉积物中细菌源有机碳的贡献率为（29.35±18.73）%,其水平分布显示出湾内西部与湾外相近且高于湾内东部的特点。细菌胞外肽酶活性（EEA）平均为（0.81±1.31）nmol/（g·h）（以MCA计）,整体分布趋势与细菌贡献率相反,呈现湾内东部高于湾内西部和湾外的特性。沉积物中有机质的不同海源、陆源占比决定了有机质的可降解性,而有机质的降解程度进一步影响了细菌源有机质的贡献与胞外肽酶活性。  相似文献   

10.
珠江口不同沉积有机质的来源及相对含量   总被引：4，自引：1，他引：4  
通过分析珠江口表层沉积物的C、N元素及C、N稳定同位素,发现其总有机碳(TOC,干重％)含量为0．06％-1．02％,其中深圳湾-内伶仃岛-澳门和珠海附近海域及香港、大亚湾附近海域表层沉积物中的TOC含量较高。总氮(TN,干重％)含量为0．03％-O．19％,TOC和TN的比值范围为1．36-7．84,反映了沉积有机质的混合来源。沉积物的^15N值为3．86‰-6．39‰,δ^13Corg值为-24．76‰--21．98‰,表明珠江口的沉积有机质主要来源于海洋有机质和陆源有机物。从河口向西,δ^13Corg值偏轻,表明由河流带入的陆源有机质受科氏力作用主要在珠江西岸沉积。  相似文献   

11.
The sources and distributions of terrigenous organic matter (OM) were investigated in a small tropical estuary in the Hainan Island, South China. Plants, suspended particulate matter (SPM), and surface sediments samples in the estuary and coast were collected. Bulk properties [organic carbon (OC%), total nitrogen (TN%), stable carbon isotope (δ13C) and grain size] and lignin phenol concentrations were measured. OC% of mangrove plants was (43.4 ± 2.1)%, which is similar to the values reported for mangrove plants in other regions. OC% of sediment samples ranged from 0.07% to 1.42%, and they were related to the sediment texture. Lignin phenols in the sediment ranged from 5.16 mg/100 mg OC in the uppermost station to 0.51mg/100mg OC in the coast. The molar ratio of organic carbon to total nitrogen (C/N) (～7) and δ 13 C (～-31.1×10-3 ) of riverine SPM revealed that the major OM sources of riverine SPM were aquatic OM (phytoplankton and/or bacteria). Moreover, the lower lignin concentration (Λ8) and higher (Ad/Al)v of lignin phenols suggest that terrestrial OM in riverine SPM were mainly from soil. Furthermore, C/N ratio, δ13C and lignin phenols reveal that mangrove plants were the predominant OM sources of mangrove surface sediment. Based on the δ13C and lignin phenols, it can be concluded that the major OM sources in estuarine and coastal surface sediments were marine phytoplankton, riverine SPM and mangrove surface sediment. In addition, the higher (Ad/Al)v of lignin phenols in those coastal sediments indicate that seagrass might be a potential OM source in coastal sediments, however, the lower (Ad/Al)v in the estuarine sediments in turn suggests that seagrass could not be transported to the mangrove fringed region. A three-end-member model which is based on lignin concentrations and δ13C was applied to evaluate the contribution of mangroves to the organic matter preserved in the surface sediments. Around the mangrove fringed region, mangrove could contribute more than 50% to the sedimentary OM, and this value is much higher than riverine OM. Nevertheless, mangrove OM could not be efficiently transported to the coastal region. Our study suggests that mangrove forest is an important OM source in this small estuary.  相似文献   

12.
近年来的研究指出红树林在海岸带碳固定和碳储存方面发挥着重要的作用。尽管印度尼西亚的红树林面积在全球占很大的比重,对于该地区红树林的有机碳储量和土壤有机碳来源的认识仍有限。本研究调查了印度尼西亚北苏拉威西海洋型的Wori红树林中生态系统有机碳储量及其空间分布特征,以及土壤有机碳的来源,以期加深该地区红树林“蓝碳”功能的认识。研究结果显示,Wori红树林0-50cm深度土壤中有机碳储量为15.4 kg/m2,占生态系统碳储量的主要部分（65%）。红树植物生物量和生态系统碳储量分别为8.3 kg/m2和23.7 kg/m2。土壤有机碳储量在不同离岸距离的采样站位中未表现出显著的空间分布差异,而生物量碳储量则在外滩最高。13C稳定同位素分析结果表明红树林土壤中蓄积的有机碳主要来源于红树林有机质,而潮水中的悬浮有机质和红树林外缘的海草并不构成红树林土壤有机碳的重要来源,它们的贡献者都低于20%。研究结果进一步证实了热带地区海洋型红树林湿地在碳储存以及红树植物对碳固定方面的重要性。  相似文献   

13.
The sources and distribution of organic matter (OM) in surface waters and sediments from Winyah Bay (South Carolina, USA) were investigated using a variety of analytical techniques, including elemental, stable isotope and organic biomarker analyses. Several locations along the estuary salinity gradient were sampled during four different periods of contrasting river discharge and tidal range. The dissolved organic carbon (DOC) concentrations of surface waters ranged from 7 mg l−1 in the lower bay stations closest to the ocean to 20 mg l−1 in the river and upper bay samples. There was a general linear relationship between DOC concentrations and salinity in three of the four sampling periods. In contrast, particulate organic carbon (POC) concentrations were significantly lower (0.1–3 mg l−1) and showed no relationship with salinity. The high molecular weight dissolved OM (HMW DOM) isolated from selected water samples collected along the bay displayed atomic carbon:nitrogen ratios ([C/N]a) and stable carbon isotopic compositions of organic carbon (δ13COC) that ranged from 10 to 30 and from −28 to −25‰, respectively. Combined, such compositions indicate that in most HMW DOM samples, the majority of the OM originates from terrigenous sources, with smaller contributions from riverine and estuarine phytoplankton. In contrast, the [C/N]a ratios of particulate OM (POM) samples varied significantly among the collection periods, ranging from low values of 5 to high values of >20. Overall, the trends in [C/N]a ratios indicated that algal sources of POM were most important during the early and late summer, whereas terrigenous sources dominated in the winter and early spring.In Winyah Bay bottom sediments, the concentrations of the mineral-associated OM were positively correlated with sediment surface area. The [C/N]a ratios and δ13COC compositions of the bulk sedimentary OM ranged from 5 to 45 and from −28 to −23‰, respectively. These compositions were consistent with predominant contributions of terrigenous sources and lesser (but significant) inputs of freshwater, estuarine and marine phytoplankton. The highest terrigenous contents were found in sediments from the river and upper bay sites, with smaller contributions to the lower parts of the estuary. The yields of lignin-derived CuO oxidation products from Winyah Bay sediments indicated that the terrigenous OM in these samples was composed of variable mixtures of relatively fresh vascular plant detritus and moderately altered soil OM. Based on the lignin phenol compositions, most of this material appeared to be derived from angiosperm and gymnosperm vascular plant sources similar to those found in the upland coastal forests in this region. A few samples displayed lignin compositions that suggested a more significant contribution from marsh C3 grasses. However, there was no evidence of inputs of Spartina alterniflora (a C4 grass) remains from the salt marshes that surround the lower sections of Winyah Bay.  相似文献   

14.
The response of mangrove ecosystems to the Asian monsoon in the future global warming can be understood by reconstructing the development of mangrove forests during the Holocene climatic optimum(HCO), using proxies preserved in coastal sediments. The total organic matter in sediments of a segmented core, with calibrated age ranges between 5.6 and 7.7 cal. ka BP and corresponding to the HCO, from the Qinzhou Bay in Guangxi, China, is quantitatively partitioned into three end-members according to their sources: mangrove-derived, terrigenous,and marine phytoplanktonic, using a three-end-member model depicted by organic carbon isotope(δ13Corg) and the molar ratio of total organic carbon to total nitrogen(C/N). The percentage of mangrove-derived organic matter(MOM) contribution is used as a proxy for mangrove development. Three visible drops in MOM contribution occurred at ca. 7.3, ca. 6.9, and ca. 6.2 cal. ka BP, respectively, are recognized against a relatively stable and higher MOM contribution level, indicating that three distinct mangrove forest degradations occurred in the Qinzhou Bay during the HCO. The three mangrove forest degradations approximately correspond to the time of the strengthened/weakened Asian winter/summer monsoon. This indicates that even during a period favorable for the mangrove development, such as the HCO, climatic extremes, such as cold and dry events driven by the strengthened/weakened Asian winter/summer monsoon, can trigger the degradation of mangrove forests.  相似文献   

15.
红树林海岸的沉积物输运和碳沉降特征   总被引：1，自引：0，他引：1  
Mangroves play an important role in sequestering carbon and trapping sediments. However, the effectiveness of such functions is unclear due to the restriction of knowledge on the sedimentation process across the vegetation boundaries. To detect the effects of mangrove forests on sediment transportation and organic carbon sequestration, the granulometric and organic carbon characteristics of mangrove sediments were investigated from three vegetation zones of four typical mangrove habitats on the Leizhou Peninsula coast. Based on our results, sediment transport was often "environmentally sensitive" to the vegetation friction. A transition of the sediment transport mode from the mudflat zone to the interior/fringe zone was often detected from the cumulative frequency curve. The vegetation cover also assists the trapping of material, resulting in a significantly higher concentration of organic carbon in the interior surface sediments. However, the graphic parameters of core sediments reflected a highly temporal variability due to the sedimentation process at different locations. The sediment texture ranges widely from sand to mud, although the sedimentary environments are restricted within the same energy level along the fluvial-marine transition zone. Based on the PCA results, the large variation was mainly attributed to either the mean grain size features or the organic carbon features. A high correlation between the depth and δ13C value also indicated an increasing storage of mangrove-derived organic carbon with time.  相似文献   

16.
Mangroves sediments contain large reservoirs of organic material (OM) as mangrove ecosystems produce large quantities and rapidly burial OM. Sediment accumulation rates of approximately 2.0 mm year−1, based on 210Pbex dating, were estimated at the margin of two well-developed mangrove forest in southern Brazil. Regional data point to a relative sea level (RSL) rise of up to ∼4.0 mm year−1. This RSL rise in turn, may directly influence the origin and quantity of organic matter (OM) deposited along mangrove sediments. Lithostratigraphic changes show that sand deposition is replacing the mud (<63 μm) fraction and OM content is decreasing in successively younger sediments. Sediment accumulation in coastal areas that are not keeping pace with sea level rise is potentially conducive to the observed shifts in particle size and OM content.  相似文献   

17.
A cross-system analysis of bulk sediment composition, total organic carbon (TOC), atomic C/N ratio, and carbon isotope composition (δ13C) in 82 surface sediment samples from natural and planted mangrove forests, bank and bottom of tidal creeks, tidal flat, and the subtidal habitat was conducted to examine the roles of mangroves in sedimentation and organic carbon (OC) accumulation processes, and to characterize sources of sedimentary OC of the mangrove ecosystem of Xuan Thuy National Park, Vietnam. Sediment grain sizes varied widely from 5.4 to 170.2 μm (mean 71.5 μm), with the fine sediment grain size fraction (< 63 μm) ranging from 11 to 99.3% (mean 72.5%). Bulk sediment composition suggested that mangroves play an important role in trapping fine sediments from river outflows and tidal water by the mechanisms of tidal current attenuation by vegetation and the ability of fine roots to bind sediments. The TOC content ranged from 0.08 to 2.18% (mean 0.78%), and was higher within mangrove forests compared to those of banks and bottoms of tidal creeks, tidal flat, and subtidal sediments. The sedimentary δ13C ranged from − 27.7 to − 20.4‰ (mean − 24.1‰), and mirrored the trend observed in TOC variation. The TOC and δ13C relationship showed that the factors of microbial remineralization and OC sources controlled the TOC pool of mangrove sediments. The comparison of δ13C and C/N ratio of sedimentary OC with those of mangrove and marine phytoplankton sources indicated that the sedimentary OC within mangrove forests and the subtidal habitat was mainly composed of mangrove and marine phytoplankton sources, respectively. The application of a simple mixing model showed that the mangrove contribution to sedimentary OC decreased as follows: natural mangrove forest > planted mangrove forest > tidal flat > creek bank > creek bottom > subtidal habitat.  相似文献   

18.
CaCO3 and total organic carbon concentrations, organic matter C/N and carbon isotope ratios, and sediment accumulation rates in late Quaternary sediments from DSDP Site 594 provide information about glacial–interglacial variations in the delivery of organic matter to the Chatham Rise offshore of southeastern New Zealand. Low C/N ratios and nearly constant organic δ13C values of −23‰ indicate that marine production dominates organic matter supply in both glacial and interglacial times during oxygen isotope stages 1 through 6 (0–140 ka) and 17 through 19 (660–790 ka). Increased organic carbon mass accumulation rates in isotope stages 2, 4, 6, and 18 record enhanced marine productivity during glacial maxima. Excursions of organic δ13C values to ca. −29‰ in portions of isotope stage 2 suggest that the local concentration of dissolved CO2 was occasionally elevated during the last glacial maximum, probably as a result of short periods of lowered sea-surface temperature. Dilution of carbonates by clastic continental sediment generally increases at this location during glacial maxima, but enhanced delivery of land-derived organic matter does not accompany the increased accumulation of clastic sediments.  相似文献   

19.
Mangroves can not only provide multiple ecosystem service functions, but are also efficient carbon producers,capturers, and sinks. The estimation of the organic carbon accumulation rate(OCAR) in mangrove sediments is fundamental for elucidating the role of mangroves in the global carbon budget. In particular, understanding the past changes in the OCAR in mangrove sediments is vital for predicting the future role of mangroves in the rapidly changing environment. In this study, three dated sediment cores from interior and fringe of mangroves in the Yingluo Bay, China, were used to reconstruct the spatiotemporal variations of the calculated OCAR since 1900 in this area. The increasing OCAR in the mangrove interior was attributed to mangrove flourishment induced by climate change characterized by the rising temperature. However, in the mangrove fringe, the strengthening hydrodynamic conditions under the sea level rise were responsible for the decreasing OCAR, particularly after the1940 s. Furthermore, the duration of inundation by seawater was the primary factors controlling the spatial variability of the OCAR from the mangrove fringe to interior, while the strengthened hydrodynamic conditions after the 1940 s broke this original pattern.  相似文献   

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