三丁基氧化锡(TBTO)对太平洋牡蛎性成熟的影响     

李琪  尾定诚  森胜义  王如才 《中国海洋大学学报(自然科学版)》2001,31(5):701-706

利用流水饲养法研究了不同浓度的三丁基氧化锡 (0 .5 μg/ L和 1.0 μg/ L TBTO)对太平洋牡蛎卵巢中卵母细胞直径、RNA/ DNA比、蛋白质和卵黄蛋白含量的影响。卵母细胞径的增长在0 .5 μg/ L实验组受到阻碍 ,并随着 TBTO浓度的增大而更加明显。TBTO暴露组的 RNA/ DNA比在精巢中无明显变化 ,但在卵巢中显著低于对照组。 TBTO暴露组的卵巢中蛋白质和卵黄蛋白含量显示了与 RNA/ DNA比相同的变化趋势 ,表明 TBTO的积累阻碍卵黄蛋白的合成。TBTO暴露4 2 d采集的牡蛎样品中出现 3个雌雄同体 ,暗示 TBTO可能引起牡蛎发生性转变进而产生雌雄同体  相似文献   

Nitrogen and oxygen isotopic composition of N₂O from suboxic waters of the eastern tropical North Pacific and the Arabian Sea—measurement by continuous-flow isotope-ratio monitoring     

T. Yoshinari  M. A. Altabet  S. W. A. Naqvi  L. Codispoti  A. Jayakumar  M. Kuhland  A. Devol 《Marine Chemistry》1997,56(3-4)

Nitrous oxide (N₂O) is a trace gas that is increasing in the atmosphere. It contributes to the greenhouse effect and influences the global ozone distribution. Recent reports suggest that regions such as the Arabian Sea may be significant sources of atmospheric N₂O.In the ocean, N₂O is formed as a by-product of nitrification and as an intermediary of denitrification. In the latter process, N₂O can be further reduced to N₂. These processes, which operate on different source pools and have different magnitudes of isotopic fractionation, make separate contributions to the ¹⁵N and¹⁸O isotopic composition of N₂O. In the case of nitrification in oxic waters, the isotopic composition of N₂O appears to depend mainly on the ¹⁵N/¹⁴N ratio of NH⁺₄ and the ¹⁸O/¹⁶O ratio of O₂ and H₂O. In suboxic waters, denitrification causes progressive ¹⁵N and ¹⁸O enrichment of N₂O as a function of degree of depletion of nitrate and dissolved oxygen. Thus the isotopic signature of N₂O should be a useful tool for studying the sources and sinks for N₂O in the ocean and its impact on the atmosphere.We have made observations of N₂O concentrations and of the dual stable isotopic composition of N₂O in the eastern tropical North Pacific (ETNP) and the Arabian Sea. The stable isotopic composition of N₂O was determined by a new method that required only 80–100 nmol of N₂O per sample analysis. Our observations include determinations across the oxic/suboxic boundaries that occur in the water columns of the ETNP and Arabian Sea. In these suboxic waters, the values of δ¹⁵N and δ¹⁸O increased linearly with one another and with decreasing N₂O concentrations, presumably reflecting the effects of denitrification. Our results suggest that the ocean could be an important source of isotopically enriched N₂O to the atmosphere.  相似文献   

现代黄河三角洲ZK226孔岩心~(210)Pb、Al、Fe、Mn和Cu的地球化学   总被引：2，自引：1，他引：2  

业渝光  和杰  刁少波  宋苏顷  蔡善琪 《海洋地质与第四纪地质》1991,(4)

现代黄河三角洲ZK226孔岩心的~(210)Pb、Al、Fe、Mn和Cu的地球化学表明,沉积物的粒度是控制上述元素的主要因素,这些元素与粒度的相关性是~(210)Pb>Fe>Al>Mn>Cu。粘土和Fe的水合氧化物是吸附~(210)Pb的主要组分。标准化后的~(210)Pb_ex,与Al、Fe,Mn和Cu的比值对黄河中上游流域的土壤侵蚀情况具有良好的指示意义,这为建立黄河中上游流域的土壤侵蚀模式打下了必要的基础。  相似文献   

几种亚热带土壤铁锰胶膜和基质的表面化学特征   总被引：1，自引：0，他引：1  

黄丽  洪军  谭文峰  刘凡 《地球化学》2006,35(3):295-303

以我国亚热带的黄褐土、黄棕壤和红壤为材料,研究了土壤铁锰胶膜和其基质的表面化学性质及其对重金属元素的吸附和氧化特点。结果表明,与基质土壤相比,铁锰胶膜的比表面积大,电荷零点(PZC)低,这与其富含粘粒、有机质和铁锰氧化物等有关;铁锰胶膜经脱锰处理后,比表面积明显降低。由盐滴定-电位滴定(STPT)法测得黄褐土、黄棕壤、红壤基质的PZC分别为3.13、3.65和3.90;黄棕壤和红壤铁锰胶膜的PZC分别为3.26和3.42。铁锰胶膜对Pb2 、Cu2 、Cd2 和Zn2 的吸附和对Cr3 的氧化能力比基质的强。铁锰胶膜经脱锰处理后,对Pb2 、Cu2 、Cd2 和Zn2 的最大吸附量比未处理时降低了53%～100%;其氧化Cr3 生成Cr6 的量比铁锰胶膜的降低了87%～100%。说明黄褐土、黄棕壤和红壤的铁锰胶膜中,氧化锰是吸附重金属离子和氧化Cr3 的主体。  相似文献   

海洋N2O的研究进展   总被引：1，自引：0，他引：1  

詹力扬  陈立奇 《地球科学进展》2006,21(3):269-277

N2O在大气中的浓度仅为CO2的浓度的千分之一左右，但在同等浓度的情况下温室效应却是CO2的200~300倍；它在大气层中的光化学产物会与臭氧反应，从而损耗平流层的臭氧。N2O的环境效应引起人们的关注，许多国际气候变化研究项目都把其列入重要研究内容。通过对过去40年的相关研究工作进行综合分析，阐述N2O在海洋中的分布规律和其影响因素、产生的机制、它的海气通量及其影响因素，从而揭示N2O的海洋生物地球化学循环过程以及这一过程对全球氮循环的贡献。  相似文献   

Extent of immobilisation of phosphate during aeration of nutrient-rich, anoxic groundwater   总被引：1，自引：0，他引：1  

Jasper Griffioen 《Journal of Hydrology》2006,320(3-4):359-369

Nutrient-rich exfiltrating groundwater may impose a heavy phosphate load on surface water systems. However, iron oxides that bind PO₄ precipitate fast upon oxygenation at neutral pH and PO₄ may also become bound in Ca precipitates following upon pH increase, so load estimates based on conservative behaviour during exfiltration will be overestimates. Aeration experiments using natural groundwater were performed to characterise the immobilisation of PO₄ within one day after aeration started. Groundwaters having a wide variety in composition, were sampled in the coastal lowlands of the Western Netherlands. Three models were considered to describe the fast binding of PO₄ by Fe oxide type phases that form upon the oxygenation of dissolved Fe(II), each based on a different concept. The concepts were surface complexation, solid-solution precipitation and two-mineral precipitation. When the experimental data were compared with model results, all three models were found to be inadequate. Frequently, more immobilisation of PO₄ occurred than could be explained by binding to a Fe oxide type of phase alone. Uptake by Ca phosphates and/or Ca carbonates must additionally have played a role; alternatively, a non-ideal phase consisting of Ca, Fe and PO₄ precipitated upon oxygenation and CO₂ degassing. A predictive multiple regression model with two primary variables that reflect the driving forces for PO₄ immobilisation was deduced that describes immobilisation of phosphate after aeration of anoxic groundwater. The two primary variables are the log value of the groundwater Fe to PO₄ molar ratio and the saturation state for hydroxyapatite after the CO₂ degassing of groundwater. The model is useful for calculating the PO₄ load of surface water from exfiltration groundwater, taking into account fast immobilisation (<1 day) during exfiltration.  相似文献   

内蒙古哈达门沟金矿床单矿物金浸出实验研究及其地质意义   总被引：4，自引：0，他引：4       下载免费PDF全文

李强之  陈衍景  徐登科  杨理勤 《矿床地质》2003,22(3):271-277

哈达门沟金矿床产于华北克拉通北缘西段，形成于伸展构造背景中，成矿流体富钾高碱且氧化性强，矿石建造中铁氧化物含量高，并且可见铁氧化物被硫化物交代的现象。文章拟揭示金在铁氧化物中的含量和赋存状态，并探讨金矿床成因。对哈达门沟金矿3种类型矿石中的黄铁矿、铁氧化物(磁铁矿和赤铁矿)单矿物进行金、铁浸取实验，结果表明：铁氧化物含金较高；黄铁矿中的金和铁的浸出曲线不同步，金浸出率与铁浸出率呈负相关，表明黄铁矿中的金主要以颗粒金形式存在；铁氧化物中金、铁同步浸出，浸出率为正相关，表明铁氧化物中的金主要以品格金和(或)胶体吸附金形式存在。哈达门沟金矿床的上述特征均表明其具铁氧化物型金矿床的特点。  相似文献   

Crystal Chemistry Research of Minerals of Nigerite Group and Its Significance     

Chen Jingzhong  Wang Fang  Han Wei  Zhang Ronghong  Peng Jue 《中国地质大学学报(英文版)》2003,14(4):293-299

SinceJacobsonandWebb (194 7)firstlyfoundthenigeriteinNigeria ,mineralogistshavefounditinmanycountriessuchasRussia (EastSiberia ,195 8) ,China(Hunan ,196 3) ,Portugal (196 5 ) ,Australia (1976 )andsoon .Greyetal.(1979)determinedaccuratelythecrystalstructureofnigerite (2 4R) .In 1988,Chenfoundakindofendmembermineralofnigerite ,whichisMg riched .ByapprovingofCommissiononNewMineralsandMineralNames (CNMMN) ,thismineralwasnamedpengzhizhongite .Inthepast ,somemineralogistsdidnotfurtherdis t…  相似文献   

盐酸羟胺—柠檬酸体系提取土壤中的游离氧化铁   总被引：5，自引：0，他引：5  

龚琦  张信贵 《岩矿测试》1998,17(4):299-302

对盐酸羟胺柠檬酸体系（９５℃水浴加热）提取土壤中游离氧化铁的实验条件进行了研究。在所选的实验条件下,该体系对土壤中游离氧化铁的提取能力与常用的连二亚硫酸钠柠檬酸钠重碳酸钠（ＤＣＢ法）体系相当,但避免了ＤＣＢ法中引入Ｎａ２Ｓ２Ｏ４给随后分离和测定造成的沉淀、基体效应等各种弊端。方法的精密度较好,ＲＳＤ（ｎ＝６）为２．５％～３．０％。  相似文献   

P507色谱分离ICP-AES法测定高纯氧化镥中14种稀土杂质     

周新军  钟妙兰  郑永凤 《铀矿地质》1998,(6)

用P507萃淋树脂一盐酸体系色谱分离、ICP－AES法测定高纯氧化镥中14种痕量稀土杂质。检测限低,抗干扰能力强,稳定性好,分离周期短,多次取样加入标准分离试验,杂质回收率在81．4％-116％,相对标准偏差为1．68％-6．01％。  相似文献