不同植物群落对灰岩试块溶蚀速率的影响   总被引：1，自引：0，他引：1  

吴孔运  蒋忠诚  叶晔 《吉林大学学报(地球科学版)》2007,37(5):967-971

用澳大利亚产的微侵蚀计,对湖南郴州礼家洞3个植物群落土壤和泉水中的灰岩溶蚀速率进行了精确测定。对取得的1 650个数据,用SPSS应用软件进行处理,发现乔木群落泉水和土壤中灰岩的平均溶蚀速率最高,分别为3.17 mm/a和0.63 mm/a。在测定灰岩溶蚀速率的同时,对泉水的水化学特征和土壤中的TOC进行了分析,发现乔木群落样地的泉水有更强的溶蚀力（较低的方解石饱和指数和较高的CO₂分压）。乔木群落土壤中的TOC比灌丛、草丛的多。与灌丛、草丛相比,乔木群落对CO₂汇的贡献最大。  相似文献   

Diagenesis of organic matter in a 400 m organic rich sediment core from offshore Namibia using solid state 13C NMR and FTIR     

《Organic Geochemistry》2014

Although rates and mechanisms of early diagenesis have been well studied, the effects of microbial metabolism on the molecular composition of the sedimentary organic matter (SOM) over long periods of time need more investigation. In this study, we characterize the early diagenesis of marine SOM from organic rich sediments of the Ocean Drilling Program site 1082 located off Namibia, in the vicinity of the Benguela coastal upwelling system. We used both Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance spectroscopy (¹³C NMR) to assess the quantitative partitioning of the organic carbon into major compound classes (aliphatic, aromatic, ester, carboxylic, amide and carbons from carbohydrates). Then, we calculate the SOM composition in the main biomolecules (proteins, carbohydrates, lipids and lignin) on the basis of previous ¹³C NMR based estimates of the molecular composition of the organic mixtures. Results show that the SOM is still labile at 7 m below the seafloor (mbsf) and composed of about 25% proteins and 15% carbohydrates. With increasing depth, the protein content exponentially decreases to 13% at 367 mbsf, whereas the carbohydrate content decreases linearly to 11%. The lignin and lipid content consistently represent around 10% and 40% of the SOM, respectively, and show an increase with depth, due mostly to selective enrichment as the more labile components are lost by degradation. Thus, these components of the SOM are considered refractory at the depth scale considered. The calculated remineralization rates are extremely slow ranging from 5.6 mol C m⁻³ ky⁻¹ at the top of the core to 0.2 mol C m⁻³ ky⁻¹ according to the organic carbon flux to the seafloor. Knowing the labile carbon losses, we propose a method to calculate the initial TOC before the diagenesis took place.  相似文献   

Temporal variation and fluxes of dissolved and particulate organic carbon in the Apure,Caura and Orinoco rivers,Venezuela     

《Journal of South American Earth Sciences》2014

The concentrations of total suspended sediments (TSS), dissolved organic carbon (DOC) and particulate organic carbon (POC) were measured in water samples taken monthly in the Apure, Caura and Orinoco rivers during a hydrological cycle (between Sept. 2007 and Aug. 2008). The DOC concentration values ranged between 1.5 and 6.8 mgC l⁻¹ in the Apure River; 2.07 and 4.9 mgC l⁻¹ in the Caura River and 1.66 and 5.35 mgC l⁻¹ in the Orinoco River. The mean concentration of DOC was 3.9 mgC l⁻¹ in the Apure River, 3.24 mgC l⁻¹ in the Caura River and 2.92 mgC l⁻¹ in the Orinoco River at Puerto Ordaz. The three rivers showed a similar temporal pattern in the concentrations of DOC, with higher DOC values during the increasing branch of the hydrograph due to wash-out processes of the organic material stored in soils. The mean concentration values of POC were 1.33 mgC l⁻¹; 0.77 mgC l⁻¹ and 0.91 mgC l⁻¹ in the Apure, Caura and Orinoco rivers, respectively. The inverse relationship found between the percentage in weight of the POC and the concentrations of TSS in the three rivers fits a logarithmic model, as it has been previously reported for other worldwide rivers. The POC concentrations in the Orinoco River showed a positive relationship with the TSS, suggesting that the POC in the Orinoco is the result of terrestrially organic matter. Although the fluxes of organic carbon (OC) in the three studied rivers are dependent on the values of water discharge, the fluxes of DOC during the increasing branch of the hydrograph are higher than those found during the decreasing stage, due to the yield of organic material accumulated in soils during the preceding dry season. The mean annual flux of total organic carbon (TOC) of the Orinoco River at Puerto Ordaz was about 4.27 × 10⁶ TonC yr⁻¹. Of this, 3.28 × 10⁶ TonC yr⁻¹ (77%) represents the flux of DOC and about 0.99 TonC yr⁻¹ (23%) represents the flux of POC. The mean annual input of TOC from the Apure River to the Orinoco River was about 4.92 × 10⁵ TonC yr⁻¹ (11.5%), while the contribution of TOC from the Caura River to the Orinoco River was estimated at 3.05 × 10⁵ TonC yr⁻¹ (7.1%).The values of annual transport of TOC calculated for the Apure, Caura and Orinoco rivers were lower than those reported twenty years ago. This could be related to interannual variations of precipitation in the Orinoco Basin, due to runoff variations can have a strong effect on the fluxes of OC from land to rivers.  相似文献   

Electro‐Fenton Treatment of Photographic Processing Wastewater     

Nasr Bensalah  Ahmed Bedoui  Shankararaman Chellam  Ahmed Abdel‐Wahab 《洁净——土壤、空气、水》2013,41(7):635-644

In this work, the treatment of photographic processing wastewaters (PPW) by electro‐Fenton process has been investigated. The Influence of operating conditions on kinetics and efficiency of electro‐Fenton process has been evaluated using carbon felt cathode and platinium (Pt) or boron‐doped diamond (BDD) anode. The results of electro‐Fenton treatment of PPW have shown that nearly complete removal of total phenols was obtained for all combinations with pseudo‐first rate constants of 0.07, 0.012, and 0.018/min for carbon felt/Pt, carbon felt/BDD and Pt/BDD cathode/anode combinations, respectively. The combination of carbon felt cathode with BDD anode achieved the highest total organic carbon (TOC) removal of 90%, while it did not exeed 40% for carbon felt/Pt combination. Increasing current intensity and Fe²⁺ dose enhances the efficiency of electro‐Fenton process. However, increasing pH decreases TOC removal during the treatment of PPW by electro‐Fenton process. The highest efficiency of electro‐Fenton process using BDD anode can be explained by the contribution of direct and indirect oxidation routes in the degradation mechanism of organics including (i) oxidation via hydroxyl radicals generated from the catalytic decomposition of H₂O₂ and from water discharge on BDD anode, (ii) direct oxidation of certain organic compounds on BDD anode, and (iii) mediated oxidation with inorganic oxidants electrogenerated from anodic oxidation of supporting salts.  相似文献   

色度学指标反映古气候的探索研究——以松辽盆地晚白垩世土伦阶（Turonian）为例     

赵斌  王亚芳  吴德新  黄永建 《吉林地质》2013,(4):1-6

本文运用色度学方法对采自松辽盆地＂松科Ⅰ井＂南孔的上白垩统泉头组四段（K2q4）、青山口组一段（K2qn1）的51件样品进行了研究,得出以下结论：（1）利用CIE1976 L＊a＊b＊表色系统分析发现,样品的色度参数L＊和a＊,b＊和a＊呈显著的负相关性（负相关系数分别达到-0.564和-0.663）,L＊和b＊则呈显著的正相关性。（2）样品的色度参数与总有机碳质量分数（TOC%）的相关性分析表明,b＊和TOC%呈现较显著的负相关性,TOC%与L＊和a＊的相关性不明显。有机碳作为碳旋回中的一部分,对松辽盆地古气候的研究具有举足轻重的意义,b＊受到总有机碳质量分数（TOC%）的制约,可以在一定程度上作为反映古气候变化的替代指标。  相似文献   

Macro- and megafauna communities in three deep basins of the South-East Atlantic     

《Deep Sea Research Part I: Oceanographic Research Papers》2013

During ‘Meteor’ expedition ‘DIVA 2’ in 2005 the abyssal macro- and megafauna communities were studied in the northern Cape Basin, in the northern Angola Basin and in the eastern and western Guinea Basin. Water depths varied between 5040 and 5670 m.Surface deposit feeding or predatory ophiuroids dominated the megafaunal community in the northern Cape Basin, sponges, sipunculids and fish in the northern Angola Basin, and asteroids, crustaceans and fish in the eastern Guinea Basin, while in the western Guinea Basin sipunculids dominated.In the northern Cape Basin, peracarid crustaceans were the dominant macrofaunal group, followed by polychaetes and bivalves. In the Guinea Basin, polychaetes, peracarid crustaceans and bivalves dominated, although omnivorous or predatory free-living nematodes of macrofaunal size (>0.5 mm) made up 40–60% of the total abundance, with maxima in the western basin.The chlorophyll a content of sediments was lower in the northern Cape and Angola Basins than in the Guinea Basin, which was consistent with the differences in water masses, primary production and flux rate of organic matter in the three basins of the South-East Atlantic. The differences in structure and function of the macro- and megafauna communities in the three basins correlated with the differences in the amount of food reaching the seafloor in tropical and subtropical settings.  相似文献   

Occurrence and distribution of antibiotics in the surface sediments of the Yangtze Estuary and nearby coastal areas   总被引：1，自引：0，他引：1  

Hao Shi  Yi Yang  Min Liu  Caixia Yan  Haiying Yue  Junliang Zhou 《Marine pollution bulletin》2014

The occurrence and distribution of five groups of antibiotics were investigated in the surface sediments of the Yangtze Estuary over four seasons. Four tetracyclines (TCs), sulfaquinoxaline (SQ), enrofloxacin (EFC) and thiamphenicol (TAP) were detected in all the samples, while sulfamerazine (SM) and sulfathiazole (ST) showed the lowest detection frequency. The detection frequencies and antibiotic concentrations were generally higher in January and May, indicating that low flow conditions and low temperature might enhance the persistence of antibiotics in sediment. Antibiotic levels varied with location, with the highest concentrations being observed around river discharges and sewage outfalls. Furthermore, a positive correlation between the concentration of quinolones and TOC revealed the significant role played by TOC. The concentration of quinolones at Wusongkou exceeded the trigger value (0.10 mg kg⁻¹) of the Steering Committee of the Veterinary International Committee on Harmonization (VICH), which should be paid attention to in future studies.  相似文献   

基于贝叶斯正则化改进BP神经网络的页岩气有机碳含量预测模型   总被引：2，自引：0，他引：2  

袁颖  谭丁  于少将  李杨  韩冰 《地质与勘探》2019,55(4):1082-1091

页岩气总有机碳(TOC)含量是评价岩性气藏的关键指标,受复杂地质及岩芯采集等多种因素的影响,常规室内测试分析获得的TOC含量的数据有限且结果有失准确。为合理准确预测页岩气TOC含量,本文首先通过对页岩气储层TOC含量测井资料综合分析选取8条测井曲线,并结合主成分分析法(Principal Component Analysis,PCA)提取四个主成分;其次基于贝叶斯正则化(Bayesian Regularization)改进的BP神经网络方法建立页岩气TOC含量预测的BR-BP模型;最后利用该模型对研究区A区页岩气TOC含量进行预测,并与常规的LM-BP神经网络模型的预测结果进行对比。结果表明：BR-BP模型有较强的非线性拟合能力,能够真实地反映出页岩气TOC含量与各测井参数之间的非线性关系,其模型预测结果与实际值基本吻合,与常规的LM-BP神经网络模型相比,其数据敏感性增强,预测精度有所提高,该研究方法具有一定的理论意义和参考价值,为我国TOC含量预测提供了一种新的技术方法和手段。  相似文献   

鹤庆钻孔沉积物总有机碳、氮含量测定的前处理方法及其环境意义   总被引：2，自引：0，他引：2  

卢凤艳  安芷生 《地质力学学报》2010,16(4):393-401

湖泊沉积物中的总有机碳含量(TOC)、总有机氮含量(TN)和碳氮比值(C/N)已被广泛应用于第四纪湖泊古环境研究中。对湖泊沉积物样品进行TOC和TN测定前, 首先要有效去除沉积物中的无机碳酸盐, 同时较好地保留有机质组分, 才能使实验结果较准确地反映古气候环境的变化。选取鹤庆钻孔不同深度的不同岩性样品, 分别进行粒度、盐酸浓度、洗除残留酸方法等对去除碳酸盐和总有机碳测定结果影响的前处理条件实验, 根据测得的TOC、TN和C/N, 结合总无机碳酸盐含量(TIC), 确定了鹤庆钻孔沉积物有机碳含量测定的前处理方法:室温条件下, 将磨得足够细(无需过筛处理)的样品与足量浓度为2mol/L盐酸充分反应24小时, 期间超声震荡3次, 采用离心加速沉淀的方法清洗酸处理样品至中性, 烘干, 研磨均匀上机测定。结果显示, 该流程可有效去除沉积物中的无机碳酸盐, 测得的TOC、TN数值具有很好的稳定性和可重复性。在此基础上测定了鹤庆钻孔沉积物样品的TOC、C/N和TIC, 它们间存在很好的正相关关系, 指示了西南季风强度的变化。   相似文献   

内蒙古西部额济纳古湖小狐山剖面有机质与碳酸盐组成及其古环境意义   总被引：6，自引：5，他引：1       下载免费PDF全文

杨伦庆  张虎才  类延斌  雷国良  张文翔  常凤琴  庞有智 《第四纪研究》2009,29(2):256-267

通过对内蒙古西部额济纳古湖小狐山剖面沉积物中总有机碳（TOC）、总氮（TN）和碳酸盐（CaCO₃）含量的测定,分析了沉积物中有机碳来源和无机碳酸盐成因,结果表明在额济纳古湖相沉积物中TOC与TN含量呈同步变化规律TOC/TN(9.91～10.16)较稳定,其有机质为湖泊自生藻类和外源维管束植物共同提供。沉积物中有机质含量受温度、降雨量变化控制,当气候暖湿时,沉积物中有机碳含量高,气候冷干则有机碳含量低,因此,有机碳含量是所研究剖面气候温湿与干旱（冷）的有效环境指标。湖泊自生碳酸盐含量则由湖区有效湿度和生物量的共同控制,其稳定碳同位素指示有效湿度的大小。粒度,特别是小于2μm组分含量与水动力和搬运介质相关,其组分含量大于5％时为湖相沉积且随其含量增加指示水深加大。根据沉积物中有机碳、碳酸盐、无机碳同位素和粒度,并结合剖面岩相特征,探讨了研究区该时段（按剖面深度划分）气候变化和湖泊演化历史：  ？～38.15 ¹⁴C kaB.P.(1039～949cm)湖区气候为冷干环境特征,风沙盛行;   38.15～31.73 ¹⁴C  kaB.P.(949～780cm)气候环境逐步改善,降水量增加,湖泊开始发育并到达湖泊高水位阶段;   31.73～22.79  ¹⁴C  kaB.P.(780～482cm)湖泊水位有所下降,气候有明显的波动,但仍维持在较高的水位上,湖区环境仍为暖湿气候;   22.79～17.37 ¹⁴C  kaB.P.(482～304cm)气候开始变冷变干,湖区有效适度持续减小,湖泊退缩;   17.37～14.00 ¹⁴C kaB.P.(304～178cm)湖泊退出研究点,区域有效湿度小,风沙盛行,存在短暂气候事件,造成暂时性流水;   14～4  ¹⁴C kaB.P.(178～0cm)湖泊开始再度扩张、水位上升,湖水变淡,到该阶段的后期气候又一次发生转变,湖区再度成为干旱环境,有效湿度减小,湖泊开始萎缩、直至消失。  相似文献