966 resultados para [ppm]
Resumo:
The geochemical and U-series isotopic characteristics of hydrothermal sulfide samples from the Jade site (127A degrees 04.5'E, 27A degrees 15'N, water depth 1300-1450 m) at Jade site in the Okinawa Trough were analyzed. In the hydrothermal sulfide samples bearing sulfate (samples HOK1 and HOK2), the LREEs are relatively enriched. All the hydrothermal sulfide samples except HOK1 belong to Zn-rich hydrothermal sulfide. In comparison with Zn-rich hydrothermal sulfides from other fields, the contents of Zn, Pb, Ag, Cd, Au and Hg are higher, the contents of Fe, Al, Cr, Co, Ni, Sr, Te, Cs, Ti and U lower, and the Pb-210 radioactivity ratios and Pb-210/Pb ratios very low. In the hydrothermal sulfide mainly composed of sphalerite, the correlations between rare elements Hf and U, and Hf and Mn as well as that between dispersive elements Ga and Zn, are strongly positive; also the contents of Au and Ag are related to Fe-sulfide, because the low temperature promotes enrichment of Au and Ag. Meanwhile, the positive correlations between Fe and Bi and between Zn and Cd are not affected by the change of mineral assemblage. Based on the Pb-210/Pb ratios of hydrothermal sulfide samples (3.99x10(-5)-5.42x10(-5)), their U isotopic composition (U-238 content 1.15-2.53 ppm, U-238 activity 1.07-1.87 dpm/g, U-234 activity 1.15-2.09 dpm/g and U-234/U-238 ratio 1.07-1.14) and their Th-232 and Th-230 contents are at base level, and the chronological age of hydrothermal sulfide at Jade site in the Okinawa Trough is between 200 and 2000 yr.
Resumo:
Thirty-six basalt samples from near East Pacific Rise 13N are analyzed for major and trace elements. Different types of zoned plagioclase phenocrysts in basalts are also backscatter imaged, and major element profiles scanned and analyzed for microprobe. Basalts dredged from a restricted area have evolved to different extents (MgO=9.38wt%-6.76wt%). High MgO basalts are modeled for crystallization to MgO of about 7wt%, and resulted in the Ni contents (28 ppm) that are generally lower than that in observed basalts (> 60 ppm). It suggests that low MgO basalts may have experienced more intensive magma mixing. High MgO (9.38wt%) basalt is modeled for self-"mixing-crystallization", and the high Ni contents in low MgO basalts can be generated in small scale and periodical self-mixing of new magma (high MgO). "Mixing-crystallization" processes that low MgO magmas experienced accord with recent 226Ra/230Th disequilibria studies for magma residence time, in which low MgO magmas have experienced more circles of "mixing-crystallization" in relatively longer residence time. Magma mixing is not homogeneous in magma chamber, however, low MgO magmas are closer to stable composition produced by periodical "mixing-crystallization", which is also an important reason for magma diversity in East Pacific Rise. Zoned plagioclase phenocrysts can be divided into two types: with and without high An# cores, both of which have multiple reversed An# zones, suggesting periodical mixing of their host magmas. Cores of zoned plagioclase in low MgO (7.45wt%) basalt differ significantly with their mantle in An#, but are similar in An# with microlite cores (products of equilibrium crystallization) in high MgO (9.38wt%) basalt, which further shows that plagioclase phenocryst cores in low MgO basalts may have formed in their parental magmas before entering into the magma chamber.
Resumo:
近年来,由于对海区不合理的开发,我国浅海贝类筏式养殖接连遭受重创,这亟需从理论上和实践中确定养殖容量和养殖模式。本文在我国北方典型养殖海湾四十里湾对筏式养殖的贝类开展了现场生理生态学研究,对贝类对浮游植物等悬浮颗粒物的处理过程即贝类对颗粒有机物及营养元素C、N、P的摄食、吸收、排泄、排粪和生长进行了剖析,分析了贝类在沿岸养殖生态系中的物质和营养循环中所扮演的角色,为海区贝类养殖容量和养殖模式的最终确定提供了基础数据。另外,本文还对海水、沉积物及生物体中磷的分析方法进行了大量的实验工作。主要结果如下:① 比较系统地评述了双壳贝类的生物沉积(biodeposition)的原理、测定方法及其生态效应。贝类通过生物沉积在沿岸生态系中的物质和营养循环中扮演着重要的角色。国际上已有不少研究专门报道了贝类在海区现场的生物沉积。而在我国,这方面的研究却罕见。② 综述了双壳贝类各种形态的 N 和 P 排泄及其生态效应。对于我国广泛养殖 的栉孔扇贝、海湾扇贝和牡蛎等双壳贝类的TDN、TP排泄尚未见报道。 ③ 在6~7月,在四十里湾的不同养殖海区(8个站位)对扇贝的生物沉积进行了现场测定。在整个四十里湾海区,一龄栉孔扇贝(壳高 41.1±4.1mm,软体干重 0.48±O.10 g/ind))每个每天所产生生物沉积物干重平均为59.9mg,对颗粒有机质(POM)、颗粒有机碳(POC)、颗粒有机氮(PON)和颗粒有机磷(POP)的生物沉积速率范围及平均值分别为: 6.88、3.09、0.392 和 0.022mg/ind·d。还在一个站位测定了海湾扇贝(壳高 24.6±2.3mm;软体干重 O.14g/ind)的生物沉积速率为 24.3mg/ind·d,或179.2mg/g·d。不同站位一龄栉孔扇贝的生物沉积速率有较大变化,这主要与饵料浓度不同有关。二龄栉孔扇贝(壳高60.9±8.2mm;软体干重1.91±0.32 g/ind)的生物沉积速率平均为 112.7mg/ind·d,对POM、POC、PON和POP的沉积速率分别是一龄扇贝的1.85倍、1.68倍、1.77倍和2.33倍。养殖海区与非养殖海区比较,前者近海底沉积速率是后者的 1.51~3.47 倍。根据以上数据,作者计算了中等规格栉孔扇贝(用壳高 41.1±4.8mm 扇贝估算)在四十里湾在夏季每天的生物沉积量达 162 吨(干重),或18.6tPOM、8.37tPOC、1.06tPON和60kgPP。在四十里湾的贝类筏式养殖海区,可以估计贝类每年因生物沉积的生产而循环427tN和98.OtP(包括20.0t OP的贡献),它们能分别满足浮游藻类生产所需求N和P的17.0%和28.3%(其中OP贡献 6.9%)。可见,贝类在养殖生态系的物质和营养盐循环中扮演着重要的角色。高密度、大面积的贝类养殖使大量的生物沉积物聚集于海底,可能对海区环境产生冲击。作者分析,98年8月份烟台养殖区赤潮的发生很可能与海底生物沉积物营养盐的快速释放以及栉孔扇贝大面积死亡而使浮游藻类失去了摄食控制有关,而风平浪静和养殖笼对水流的阻挡也为赤潮的发生提供了有利条件。④ 采用半现场流水系统法测定了栉孔扇贝在不同养殖密度、不同养殖模式(扇贝单养、贝藻混养、贝藻参混养)中的生物沉积。实验时间尺度大,前后计80天。结果说明扇贝的生物沉积速率与其养殖密度呈反比关系。养殖密度的高低影响饵料浓度的变化(两者呈负相关的对数函数关系),而饵料浓度的高低直接决定着扇贝的生物沉积速率的高低,两者呈正相关关系(生物沉积速率与POC和叶绿 a 分别呈对数和指数函数关系)。不仅生物沉积物的数量与养殖密度(或饵料浓度)有关,生物沉积物的质量同样与养殖密度(或饵料浓度)有关。栉孔扇贝的养殖使沉积物的有机质含量及C、N 和 P 含量降低,且密度越高,它们的含量越低。这反映了扇贝对环境的适应能力。在海带和扇贝的混养模式中,海带对扇贝生物沉积物的数量和质量不构成影响,当然这是在海带不影响浮游植物数量的前提下得出的结果。而实际上在自然海区两者可能是竞争关系。⑤ 对从海区取回到实验室的多种滤食性动物,包括经济双壳贝类(栉孔扇贝、海湾扇贝、长牡蛎、贻贝、菲律宾蛤仔等)和养殖中的污损动物(栖海鞘、玻璃海鞘、藤壶、玟斑稜蛤)的 N 和 P 排泄进行了测定,包括排泄成分和排泄速率。在N排泄中,NH_4-H 占主要部分,如笼式养殖的双壳贝类 NH_4-N 占总N排泄的70%以上,平均值范围为70.8~80.1%。氨基酸是第二大排泄成分,平均占总N排泄的10~25%。其它形态的N,如尿素、亚硝酸盐和硝酸盐也有检出,如双壳贝类尿素氮在总氮排泄中占 2~5%。但在双壳贝类中未检出尿酸氮。比较而言,海鞘、藤壶的尿素氮相对高一些。在P排泄中,OP约占TDP排泄的15~27%。栉孔扇贝TDP排泄速率为0.281μmol/h·ind。作者以实验室测定结果计算,在整个四十里湾的夏季,所养殖的双壳贝类每天将排泄4.54t总溶解氮,其中NH_4-N 3.36t、Amino-N 0.69t、Urea-N 0.2t。 同时每天磷的排泄为0.57t TDP,其中OP O.15t。对面积为1.3 * 10~4hm~2的海区而言,贝类的N、P排泄分别能满足浮游植物生产所需N、P的44%和40%。尽管Urea-N所占比例有限,但也能满足海区浮游植物所需 N 的 2%左右。以上说二月高密度的贝类养殖对海区生态系统营养盐循环的影响是很显著的。附着动物(柄海鞘等)的N、P 排泄也不容忽视,它们分别能满足浮游藻类生产所需 N、P 的 ll%和 12%。它们一方面通过排泄和排粪加速营养盐和物质的循环对浮游植物的生长产生刺激作用;另一方面,对藻类产生摄食控制,如果海区中滤食性动物太多,即使营养盐再丰富也难以使浮游植物大量繁殖,这无疑将影响滤食性动物的生长速率。⑥ 运用近年来发展起来的生物沉积法对四十里湾半现场流水系统中贝类的滤水率、吸收率、生长率、生态效率等生理生态学参数进行了测定。栉孔扇贝(收获时规格0.194~0.412g软体干重/ind)滤水率平均为3.65 1/ind·h。扇贝放养密度和饵料浓度没有显著关系。扇贝的总摄食率平均为3.98mg/ind·h,对POM、POC、PON的 摄食率范围为0.84~1.87、0.335~0.748、0.0515~O.1293mg/ind·h。扇贝的摄食率随放养密度的升高而降低,与POM呈正相关关系。扇贝的吸收速率受密度和饵料浓度的影响不明显。扇贝对N的吸收效率较C、P稍高,对总有机质的吸收效率为75.9±4.1%,如此高的吸收效率与低饵料浓度有关。扇贝氨基酸泄漏所损失的能量高于排氨的能量损失。代谢能与吸收能呈明显的正相关关系。SFG与饵料浓度呈正相关关系。总生长效率K1(* 100)变化较大,范围为20~49;净生长效率K,K_2(* 100)随POM的升高而升高。扇贝对N的总生态效率范围为6.2~12.8%(平均9.9%),这高于对C(平均5.9%)和P(平均4.1%)的总生态效率。扇贝对POC、PON和PP的生长余力(SFG_C、SFG_N、SFG_P)平均分别为197、46.8和6.2μg/ind·h,它们分别与POC、PON和PP呈正比关系。扇贝对N的净生长率高于对C和P的净生长率。在N的预算中,如果仅考虑NH_4-N的排泄而忽视其它形态氮的排泄,将会产生很大偏差(平均约20%)。扇贝贝壳生长所需的能量在整个扇贝生长所需能量的9.0~15.1%(平均 11.2%);贝壳C、N和P在扇贝生长中所占的比例分别为10.5~17.8%、9.4~16.1%和8.7~15.O%。可见,贝壳不管在能量预算还是在元素预算中都不应该被忽视。理论计算而得到的SFG和SFG_C、SFG_N、SFG_P与扇贝的实际生长和扇贝C、N、P的实际增长量之间呈正相关关系,但前者明显过高地估计了扇贝的生长。⑦ 运用生物沉积法在四十里湾养殖海区现场对栉孔扇贝的生理生态学特征进行了研究。不同海区扇贝的滤水率有变化,一龄扇贝(41.1±4.1mm,软体干重 0.48±O.10g/ind)滤水率变化范围为 0.72~2.54(平均 1.27)1/ind·h 或 1.65~5.97(平均 2.61)1/g·h。与半现场研究结果一致,滤水率与TPM没有明显关系,而摄食率却与TPM呈正相关关系。二龄扇贝(软体干重 1.91±0.32g/ind)滤水率为 2.09~3.99(平均 3.10)1/ind·h。吸收速率与POM(或TDM)呈正相关关系,与饵料质量(POM/TPM)无明显的相关关系。吸收效率AE_(POM)与TPM(或POM)没有相关关系,却与饵料质量呈明显 的正相关关系。扇贝对POC、PON和PP的吸收效率平均分别为68.9%、64.0%和63.6%。不同海区SFG差别很大。一龄扇贝SFG范围为-O.174~24.08 J/ind·h,SFG与饵料浓度POM呈正相关关系。SFG负值的出现主要与低饵料浓度有关。SFG_C、SFG_N、SFG_P分别与POC、PON和PP呈正相关关系。在N的生长余力计算中,如果仅考虑NH_4-N排泄,而不考虑其它形态N的排泄,就可能产生相当大的偏差,偏差范围为11~360%,这高于半现场的偏差值,显然SFG_N越低,产生的偏差就越大。这说明在饵料不足、扇贝生长受到限制的环境下进行N生长余力的计算时必须考虑其它形态N的排泄。⑧ 对四十里湾养殖海区一些双壳贝类和藻类的化学组成和有机净生产量进行了讨论。不同双壳贝类的软体有机碳含量差别不大,而N含量差异较大。栉孔扇贝N含量最高(占软体干重的12.36%),而牡蛎、毛蚶软体N含量相对较低,为 8~9%。从双壳贝类贝壳的组成来看,贻贝和菲律宾蛤仔贝壳中N含量最高,分别为 0.55% 和 0.56%;而栉孔扇贝贝壳N含量相对较低,在 O.1%左右。贻贝贝壳有机磷含量 (308ppm) 也明显高于栉孔扇贝贝壳(62.1 ppm)。不同海区海带的 C/N 比值较高,变化明显,范围为17.36~30.23。石莼与此相似。大型藻类高 C/N 比值说明海区营养元素N的不足。海带的不同部位N含量差别很大,中带部和边叶在不同海区有较大变化,即对环境的营养状况比较敏感。紫贻贝贝壳中C、H、N 和 P 的含量在整个贻贝中占有相对大的比例,分别为 30.4%、30.2%、31.8%和 29.6%。
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本文采用组织学手段研究了牙鲆性腺在分化、发育和成熟过程中的变化。然后,通过放射性免疫方法(RIA)测定了牙鲆仔稚幼鱼全组织匀浆液中的性类固醇激素—睾酮(T)和雌二醇(E2)的含量,并结合牙鲆血清中T和E2含量的年周期测定,从内分泌学水平探讨了T和E2在其性腺分化、发育和成熟过程中水平的变化规律。同时,采用高温和雌性激素对性腺未分化的普通和雌核发育牙鲆仔稚鱼进行诱导处理,获得了较高比例的雄性鱼/假雄鱼或100%雌性鱼;并研究了这些外界环境因子对牙鲆性腺分化、性别比率及体内T和E2水平的影响,藉此探讨了牙鲆性别决定与性腺分化的细胞学和内分泌学机制。 对牙鲆仔稚幼鱼性腺的组织切片观察发现,培育水温18~20℃下,孵化后第45天、平均全长<22.0±2.8 mm的牙鲆,其性腺分化尚未开始,属于原始性腺;在孵化后70日龄、平均全长为38.0±1.7 mm左右,部分个体中观察到卵巢的雏形,其余个体的性腺在此阶段以及之后的一段时间内变化并不明显;到了第110天、平均全长达到86.5±5.9 mm时,雌性个体卵巢出现了卵原细胞向卵母细胞的转变,标志着卵巢分化的结束。在90日龄、平均全长为63.5±3.4 mm的雄性牙鲆中,精原细胞快速增殖,并观察到了输精管结构;进一步的细胞学分化则出现在100日龄、平均全长为76.0±8.6 mm的个体中,此时可以看到精小叶的形成;在平均全长为140.0±15.2 mm时,精巢中出现初级精母细胞,标志着性腺分化的基本完成。 对牙鲆仔稚幼鱼全组织匀浆和成鱼血清中的T和E2水平的比较发现,在全长为6 mm左右的仔鱼中T和E2含量均较高。随后,在性腺分化过程中T含量大大降低,E2的含量急剧增高,而性腺分化后期E2含量又降到较低的水平。在雄性牙鲆成鱼中, 从精巢第Ⅲ期开始,T含量随着精巢的发育而增加,到了精巢第Ⅴ期性腺发育成熟并排精后,又降低到较低的水平;E2含量在从精巢第Ⅲ期发育至精巢第Ⅴ期过程中略呈降低的趋势,但是总体上来说没有明显的差异。在雌性牙鲆成鱼中,卵巢从第Ⅱ期到第Ⅳ期的过程中,T水平逐渐升高,在第Ⅴ期时则明显降低;而E2含量在卵巢第Ⅱ期时保持较低的水平,随着卵巢的发育,E2含量逐渐增高,在卵巢第Ⅳ期时达到最高水平,在第Ⅴ期产卵后又有所降低。在雌雄个体中T和E2均呈现周期性的变化。5月份随着水温的升高,雄性个体T和E2含量显著上升;到了9月份又逐渐下降至最低值。雌性个体E2含量自3月份开始增高,在5月份急剧升高,并在6月份达到最高值;在7月份的时候,E2突然降低,而到了8月份又有所回升;9月份之后E2逐渐降低并在1月份左右降到最低;而T的含量分别在2月份和6月份出现两次高峰。 温度诱导牙鲆幼鱼性腺分化的结果表明,牙鲆中存在明显的TSD机制,即其性腺分化因饲育水温的不同而变化:在一定温度范围内,随着饲育温度的增加,牙鲆的雄性比例逐渐增高,常温对照组和21℃组中的雄性比例分别为51.62%、60.00%,而在24℃和28℃高温组中,雄性比例显著高于对照组,分别达到73.33%和87.27%。T和E2含量测定显示,在性腺分化时期,高温和对照组中T含量没有明显的变化,而温度处理组中的E2水平则低于对照组,特别是在28℃高温组,其E2水平显著低于对照组(P<0.05)。外源E2处理性腺未分化的牙鲆幼鱼的结果也表明,牙鲆的死亡率与雌性化比率均为雌性激素剂量依赖型的。随着外源E2剂量的增加,雌性比率增加,但同时死亡率也增高。此期间T和E2水平比较发现,在性腺分化时期,对照组中的T含量稍高于雌激素处理组;而对照组中的E2含量高于0.2 ppm和2 ppm两个低剂量组,却低于20 ppm和100 ppm两个高剂量组。 同时,还对人工诱导培育的雌核发育牙鲆和性反转牙鲆进行了性腺发育观察,在所观察的雌核发育牙鲆个体中,其雌性比例为83.33%,而高温28℃饲育群体中的雄性比例(即假雄鱼比例)为91.67%;在雌性个体中,也有一定比例的个体性腺发育不正常,有的性腺发育较小,有的则缺少部分性腺。进一步对雌核发育成体的血清中T和E2含量进行测量,发现在普通牙鲆个体中T含量显著低于雌核发育个体,而E2含量则高于雌核发育牙鲆;在雌核发育牙鲆中,性腺发育不正常的个体比性腺发育正常的个体中的T含量稍高,而E2含量则显著低于正常雌核发育牙鲆个体和普通牙鲆个体(P< 0.05)。
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The North Atlantic spring bloom is one of the largest annual biological events in the ocean, and is characterized by dominance transitions from siliceous (diatoms) to calcareous (coccolithophores) algal groups. To study the effects of future global change on these phytoplankton and the biogeochemical cycles they mediate, a shipboard continuous culture experiment (Ecostat) was conducted in June 2005 during this transition period. Four treatments were examined: (1) 12 degrees C and 390 ppm CO2 (ambient control), (2) 12 degrees C and 690 ppm CO2 (high pCO(2)) (3) 16 degrees C and 390 ppm CO2 (high temperature), and (4) 16 degrees C and 690 ppm CO2 ('greenhouse'). Nutrient availability in all treatments was designed to reproduce the low silicate conditions typical of this late stage of the bloom. Both elevated pCO(2) and temperature resulted in changes in phytoplankton community structure. Increased temperature promoted whole community photosynthesis and particulate organic carbon (POC) production rates per unit chlorophyll a. Despite much higher coccolithophore abundance in the greenhouse treatment, particulate inorganic carbon production (calcification) was significantly decreased by the combination of increased pCO(2) and temperature. Our experiments suggest that future trends during the bloom could include greatly reduced export of calcium carbonate relative to POC, thus providing a potential negative feedback to atmospheric CO2 concentration. Other trends with potential climate feedback effects include decreased community biogenic silica to POC ratios at higher temperature. These shipboard experiments suggest the need to examine whether future pCO2 and temperature increases on longer decadal timescales will similarly alter the biological and biogeochemical dynamics of the North Atlantic spring bloom.
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Very little is known about how global anthropogenic changes will affect major harmful algal bloom groups. Shifts in the growth and physiology of HAB species like the raphidophyte Heterosigma akashiwo and the dinoflagellate Prorocentrum minimum due to rising CO2 and temperature could alter their relative abundance and environmental impacts in estuaries where both form blooms, such as the Delaware Inland Bays (DIB). We grew semi-continuous cultures of sympatric DIB isolates of these two species under four conditions: (1) 20 degrees C and 375 ppm CO2 (ambient control), (2)20 degrees C and 750 ppm CO2 (high CO2),(3) 24 degrees C and 375 ppm CO2 (high temperature), and (4) 24 degrees C and 750 ppm CO2 (combined). Elevated CO2 alone or in concert with temperature stimulated Heterosigma growth, but had no significant effect on Prorocentrum growth. P-Bmax (the maximum biomass-normalized light-saturated carbon fixation rate) in Heterosigma was increased only by simultaneous CO2 and temperature increases, whereas P-Bmax in Prorocentrum responded significantly to CO2 enrichment, with or without increased temperature. CO2 and temperature affected photosynthetic parameters alpha, Phi(max), E-k, and Delta F/F'(m) in both species. Increased temperature decreased and increased the Chl a content of Heterosigma and M Prorocentrum, respectively. CO2 availability and temperature had pronounced effects on cellular quotas of C and N in Heterosigma, but not in Prorocentrum. Ratios of C:P and N:P increased with elevated carbon dioxide in Heterosigma but not in Prorocentrum. These changes in cellular nutrient quotas and ratios imply that Heterosigma could be more vulnerable to N limitation but less vulnerable to P-limitation than Prorocentrum under future environmental conditions. In general, Heterosigma growth and physiology showed a much greater positive response to elevated CO2 and temperature compared to Prorocentrum, consistent with what is known about their respective carbon acquisition mechanisms. Hence, rising temperature and CO2 either alone or in combination with other limiting factors could significantly alter the relative dominance of these two co-existing HAB species over the next century. (c) 2007 Elsevier B.V. All rights reserved.
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An assessment of metal contamination in surface sediments of the Jiaozhou Bay, Qingdao, one of the rapidly developing coastal economic zones in China, is provided. Sediments were collected from 10 stations and a total of 15 heavy metals were analyzed. Concentrations of metals show significant variability and range from 210 to 620 ppm for Ti, 2.7 to 23 ppm for Ni, 4.2 to 28 ppm for Cu, 5.2 to 18 ppm for Pb, 12 to 58 ppm for Zn, 0.03 to 0.11 ppm for Cd, 5 to 51 ppm for Cr, 1.5 to 9.9 ppm for Co, 5.3 to 19 ppm for As, 12 to 32 ppm for Se, and 19 to 97 ppm for Sr. Based on concentration relationships and enrichment factor (EF) analyses, the results indicate that sediment grain size and organic matter played important roles in controlling the distribution of the heavy metals in surface sediments of the Jiaozhou Bay. The study shows that the sediment of the Jiaozhou Bay has been contaminated by heavy metals to various degrees, with prominent arsenic contributing the most to the contamination. The analysis suggests that the major sources of metal contamination in the Jiaozhou Bay are land-based anthropogenic ones, such as discharge of industrial waste water and municipal sewage and run-off. Notably, the elevated heavy metal concentrations of the Jiaozhou Bay sediments could have a significant impact on the bay's ecosystem. With the rapid economic development and urbanization around the Jiaozhou Bay, coastal management and pollution control should focus on these contaminant sources, as well as provide ongoing monitoring studies of heavy metal contamination within the bay.
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Hydrogen permeation behaviours of high strength steel 35CrMo under different cyclic wet-dry conditions have been investigated by using Devanathan-Stachurski's technique. Four electrolytes were used: distilled water, seawater, seawater containing 1500 ppm H2S and seawater containing 0.03 mol L-1 SO2. The corrosion weight loss of 35CrMo in the wet-dry cycles was measured simultaneously. The experimental results show that hydrogen can be detected at the surface opposite to the corroding side of the specimen during wet-dry cycles and the permeation current density during a wet-dry cycle showed a maximum during the drying process. The hydrogen permeation was obviously promoted by Cl- ions, H2S and SO2. The hydrogen permeation in the real marine atmosphere has also been investigated. There is a clear correlation between the amount of hydrogen permeated and the corrosion weight losses. Results show the importance of hydrogen permeation that merits further investigation.
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Hydrogen permeation of 16Mn steel under a cyclic wet-dry condition was investigated by Devanathan-Stachurski's electrolytic cell with a membrane covered on the exit side by a nickel layer and the weight loss was measured for each wet-dry cycle. The results show that hydrogen permeation current change with different atmospheric environment: distilled water, seawater, and seawater containing 100 ppm H2S. The results show that seawater can induce an increase in the hydrogen permeation current due to the hydrolyzation reaction. And after the increase, equilibrium is reached due to the equilibrium of hydrolyzation reaction effect and the block of the rust layer. On the other hand, H2S contamination also can induce an increase in the maximum hydrogen permeation current due to the hydrolyzation reaction. And H2S contamination delays the time that hydrogen permeation is detected because of the formation of the FeS(1-x) film. The FeS(1-x) film can block the absorption of hydrogen onto the specimen surface. The surface potential change and the pH change of the metal surface control the hydrogen permeation current. And a clear linear correlation exists between the quantities of hydrogen permeated through the 16Mn steel and the weight loss. Based on the linear correlation, we monitored the corrosion rate by monitoring the hydrogen permeation current by a sensor outside. Good coherences were shown between results in laboratory and outside.
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The botanical insecticide azadirachtin affects a variety of biological processes. Our early work indicated that protein level and type are significantly influenced by azadirachtin in pupae of Osttiniafumacalis (Guenee) (Lepidoptera: Crambidae) because a correlation exists between protein content and azadiraebtin concentration. By use of proteomic techniques, we analyzed changes in hemolymph protein expression of 48-h-old pupae in O. furnacalis induced by azadirachtin treatment. After feeding by third instars on an artificial diet containing 10 ppm azadirachtin until pupation, 48-b-old pupae were collected, and hemolymph protein samples were prepared. They were separated by two-dimensional polyacrylamide gel electrophoresis, and six proteins were significantly affected by azadiracbtin treatment compared with an untreated control. Two of these proteins were identified by database searching with peptide mass fingerprinting by using matrix-assisted laser desorption/ time-of-flight mass spectrometry after in-gel trypsin digestion. They belong to the insect apolipophorin-III and phospboribosyltransferase family, respectively. These two proteins may function on lipid metabolism in insect hemolymph. Furthermore, fat body is the center of synthesis and secretion of hemolymph proteins. We suggest that the azadirachtin exerts its insecticidal effects on the fat body of O. furnacalis by interfering with protein expression related to hemolymph lipid metabolism.
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The most novel aspect of this thesis is the combination analysis of the boron isotopes and trace elements. What’s more, it also provides a reliable analytical technique, which is suitable for both boron isotopes and trace elements. Al/Ca values can be used to monitor the clay removal during the sample preparation. It is found that when Al/Ca>100 mol/mol, the measured boron isotopic compositions are always several permil lower than those properly cleaned. B/Ca ratios can be used to calculate the exact boron loaded for each sample. Otherwise, too much loading will lead to too long time for the whole analytical sequence, and too less loading might incur serious blank problem. One other benefit besides those discussed above is that the combination analysis of boron isotopes and trace elements on the same sample allows reconstruction of the marine carbonate system and atmospheric pCO2 without assumption of the other parameter. In the marine carbonate system, with the seawater pH from the foraminiferal 11B, one has to make an assumption on the other variable to obtain the rest four variables. A series studies found that U/Ca and B/Ca are potential proxies for seawater [CO32-]and [HCO3-], respectively. Since they are measured on the same sample with boron isotopes, hence, there is no spatial or temporal ambiguity in the incorporation of the two controlling parameters. With 11B and U/Ca, the reconstructed atmospheric pCO2 variations match the atmospheric pCO2 record from the Vostok ice core within ±20 ppm. The incorporations of U and B into foraminiferal carbonates are controlled by the overall growth rate of individual foraminifers and other possible factors. The reliable application of these proxies still require further calibrations. In a similar fashion, the combination analysis of boron isotopes and Mg/Ca also has great advantages. Mg/Ca has been proved to be a reliable proxy for the surface seawater temperature. With the combination analysis, one can determine the phase between changes in atmospheric pCO2 and surface seawater temperature, thus explore the cause and mechanism of the changes in atmospheric pCO2. .
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The occurrence of Late Cretaceous mafic dykes and their entrained peridotite and granulite xenoliths as well as clinopyroxene xenocrysts in the Qingdao region provide us a precious opportunity to unveil the nature and characteristics of the Late Mesozoic lithospheric mantle and lower crust beneath the Jiaodong region, and the change of the magma sources. These studies are of important and significant for understanding the lithospheric evolution in the eastern North China Craton. There were two periods of magma activities in Late Mesozoic in Qingdao Laoshan region, one was around 107Ma in the Early Cretaceous and the other around 86Ma in the Late Cretaceous according to the whole rock K-Ar age determination. The Early Cretaceous mafic dykes and the Late Cretaceous mafic dyke (i.e. Pishikou mafic dike) have completely different geochemical characteristics. The Early Cretaceous mafic dykes are enriched in LILE, strongly depleted in HFSE (Nb, Ta, Zr, Hf) and characterized by the highly radiogenic Sr and Nd isotopic compositions. These geochemical features indicate that the Early Cretaceous mafic dykes were derived from an enriched lithospheric mantle. In contrast, the Late Cretaceous mafic dyke is enriched in LILE, without HFSE depletion (Nb, Ta, Zr, Hf) and has less radiogenic Nd and Sr isotopic compositions. These geochemical features indicate that the Late Cretaceous mafic dyke was derived from the asthenosphere modified by subducted pelagic sediment contamination. The intrusive age of the Late Cretaceous mafic dyke provides further information for the termination of the lithosphere thinning for the eastern North China Crtaon. Pishikou Late Cretaceous mafic dyke contains abundant peridotitic xenoliths, granulite xenoliths and clinopyroxene xenocrysts. The peridotitic xenoliths can be divided into two types: high Mg# peridotites and low Mg# peridotites, according to their textural and mineral features. The high-Mg# peridotites have high Fo (up to 92.2) olivines and high Cr# (up to 55) spinels. The clinopyroxenes in the high# peridotites are rich in Cr2O3 and poor in Al2O3. The low-Mg# peridotites are typified by low Mg# (Fo <90) in olivines and low Cr# (Cr# <0.14) in spinels. The clinopyroxenes in the low-Mg# peridotites are rich in Al2O3 and Na2O and poor in Cr2O3. These two type peridotites have similar equilibrated temperatures of 950C-1100C. The Clinopyroxenes in the high-Mg# peridotites generally have high and variable REE contents (REE = 5.6-84 ppm) and LREE-enriched chondrite-normalized patterns ((La/Yb)N>1). In contrast, the clinopyroxenes in the low-Mg# peridotites have low REE contents (REE = 12 ppm) and LREE-depleted patterns ((La/Yb)N<1). The textural, mineral and elemental features of the low-Mg# peridotites are similar to those of the low-Mg peridotites from the Junan, representing the newly-accreted lithospheric mantle. However, the mineralogical and petrological features of the high-Mg# peridotites are similar to those of the high-Mg# peridotites from the Junan region, representing samples from the old refractory lithospheric mantle that was strongly and multiply affected by melts of different origins Late Cretaceous mafic dike in the Qingdao region also contains two types of granulite xenoliths according to the mineral constituents: the pyroxene-rich granulites and the plagioclase-rich granulites. Equilibrated temperatures calculated from the cpx-opx geothermometers are in a range of 861C - 910C for the pyroxene-rich granulites and of 847C - 890C for the plagioclase-rich granulites. The equilibrated pressure for the plagioclase-rich granulites is in a range of 9.9-11.7 kbar. Combined with the results of the peridotitic xenoliths, a 40C temperature gap exists between the peridotite and the granulite. The petrological Moho was 33~36 km at depths, broadly consistent with the seismic Moho estimated from the geophysical data. This indicates that there was no obvious crust-mantle transition zone in the Qingdao region in the Late Mesozoic. Pishikou Late Cretaceous mafic dyke entrained lots of clinopyroxene xenocrysts which are characterized by the chemical zoning. According to the zoning features, two types of clinopyroxene xenoliths can be classified, the normal zoning and the revise zoning. The normally-zoned clinopyroxene xenocrysts have LREE-depleted REE patterns in the cores. In contrast, the revisely-zoned clinopyroxenes have LREE-enriched REE patterns in the cores. According to the rim and core compositions of xenocrysts, all the rims are balanced with the host magma. Meanwhile, the origins of the cores were complicated, in which the normally-zoned clinopyroxenes were derived form the lithospheric mantle and some of the reversely-zoned clinopyroxnes were originated from the lower crust. Other revisely-zoned clinopyroxenes had experienced complex geological evolution and need to be further investigated. According to the above results, a simplified lithospheric profile has been established beneath the Qingdao region and a constraint on the nature and characteristics of the lithospheric mantle and lower crust has been made.
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Cambrian-Ordovician dolostones in Tarim Basin are hydrocarbon reservoir rocks of vital importance. Under the guidance of the theories of sedimentology and the sedimentology of carbonate reservoir, based on the first-hand qualitative and quantitative data especially, combined with micro-study, geochemical and reservoir capacity analysis, and precursor research, the origin and reservoir characteristics of the dolostones were discussed. Based on detailed petrographic investigations, four types of dolostone have been recognized, which are, respecitively, mud-silt-sized dolostones, algal laminated dolostones (ALD), prophyritic dolostone, and neomorphic dolostone. Mud-silt-sized dolostones always presents as laminas together with evaporated signatures, its REE patterns and ΣREE are all close to that of the finely crystalline limestone. This kind of dolomite probably experienced relatively low fluid-rock ratio during diagenesis was formed in hypersaline and oxidizing environment and involved fast dolomitization process. It was dolomitized by evaporated seawater in sabkha environment.The main primary fabrics of algal lamination in algal laminated dolomite (ALD) can still be identified and its ΣREE (21.37) is very close to that of algae. This reveals that ALD was dolomitized during early diagenesis and algae possibly played an important role. The ALD was formed under mediation of organic matter and Mg2+ were supplied by magnesium concentrated algal laminites and sea water. Prophyritic dolostones presents mainly as patchy occurrence and yield the lowest δ13C and Z value. Its ΣREE is much less than that of the finely crystalline limestone. These characteristics reveal that the cloudy cores were dolomitized in shallow early diagenetic environments by pore fluids riched in Mg2+. Whereas the clear rims were likely formed in subsequent burial into deeper subsurface environments, and the Mg2+ needed for further dolomitization possibly was supplied by the transformations of clay minerals. Neomorphic dolostones consist of coarse, turbid crystals and exhibits sucrosic and mosaic textures. It has highest Fe2+ contents and average homogeneous temperature (110.2℃). Collectively, these characteristics demonstrate that the neomorphic dolostones was likely formed by recrystallization of pre-existing dolomites during deep burial. The ΣREE of the four types of dolostone distinctly differentiates from each other. However, their REE patterns are all enriched in LREE, depleted in HREE and have Eu negative anomalies. Its ΣREE 13.64 ppm, less than 1/4 of finely crystalline limestone, and ranks the lowest in the 4 types.These characteristics are comparable to those of finely crystalline limestone, and are mainly infuenced by the sea water. These four types of dolostone show similar REE mobility behaviour and no significant fractionation, althouth they have been subjected to evidently different diageneses. Seven main pore types are identified in the dolostones , which are fenestral, moldic, intercrystal, dissolved,breccia, dissolved breccia and stylolite pores. Fenestral pores are primary and the others are secondary. The dissolved pores and intercrystal pores are the most important reservoir spaces and followed by breccias and dissolved breccia pores, and the moldic and fenestral pores are less important. Stylolites can enhance permeability of reservoir rocks in one hand, for the other hand, the capacity of reservoir and permeability are enhanced and then better reservoir rocks can be formed when they are combined with patchy dolostones. The relationship between porosity and the type of dolostones is that the dissolved neomorphic dolostones have the highest porosity of 3.65%, than followed by dissolved Mud-silt-sized dolostones of 3.35%. The mud-silt-sized dolostones without dissolution have the lowest porosity of 0.90%. Moreover, the porosity of prophyritic dolostones and the neomorphic dolostones without dissolution are lower, respectively 1.675% and 1.41%. Although algal laminated dolostones consist of euhedral crystals and riched in intercrystal pores, its porosity just yields 1.20%. The relationship between permeability and the type of dolostones is that that algal laminated dolostones have the highest permeability of 0.462mD and followed by 0.065mD of prophyritic dolostones. Dissolution have no significant influence on the permeability of neomorphic dolostones and this presented by the permeability of dissolved and non-dissolved are very close, respectively 0.043mD and 0.062mD. No matter dissolved or not, mud-silt-sized dolostones are much less permeable. The permeability of non-dissolved and dissolved are 0.051mD and 0.016mD. Collectively, in the study area, neomorphic dolostones can form high quality reservoir.
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As powerful tools to study the lithosphere dynamics, the effective elastic thickness (Te) as well as the envelope of yielding stress of lithosphere have been attracted great attention of geoscientists in the past thirty years. The oceanic lithosphere, contrary to the continental lithosphere, has more fruits for its simple structures and evolution process. In continent, the lithosphere commonly is complex and variable in the rheological, thermal structures, and has a complicated history. Therefore, the application of the effective elastic thickness in continent is still a subject to learn in a long time. Te, with the definition of the thickness of an elastic plate in theory flexured by the equal benging of the real stress in the lithosphere plate (Turcotte, 1982), marks the depth of transition between elastic and fluid behaviors of rocks subjected to stress exceeding 100 MPa over the geological timescales (McNutt, 1990). There are three methods often adapted: admittance or isostatic response function, coherence and forwarding. In principle, the models of Te consist of thermal-rheological, non-linear Maxwell, non-linear work hardening and rheological layered models. There is a tentative knowledge of Te that it is affected by the following factors: crustal thickness, crust-mantle decoupling, plate bending, boundary conditions of plate (end forces and bending moments), stress state, sedimentary layer, faulting effect, variation in the mountain belts' strike, foreland basin, inheritance of tectonic evolution, convection of mantle, seismic depth and lithosphere strength. In this thesis, the author introduces the geological sketch of the Dabie collisional orogenic belt and the Hefei Basin. The Dabie Mts. is famous for the ultra-high pressure metamorphism. The crustal materials subducted down to the depth of at least 100 km and exhumed. So that the front subjects arise such as the deeply subduction of continent, and the post-collisional crust-mantle interaction. In a geological journey at June of 1999, the author found the rarely variolitic basaltic andesite in the Dabie Mts. It occurs in Susong Group, near Zhifenghe Countryside, Susong County, Anhui Province. It is just to the south of the boundary between the high-grade Susong melange and the ultra-high grade South Dabie melange. It has a noticeable knobby or pitted appearance in the surface. The size of the varioles is about 1-4 mm. In hand-specimen and under microscope, there are distinct contacts between the varioles and the matrice. The mineralogy of the varioles is primarily radiate plagioclase, with little pyroxene, hornblende and quartz. The pyroxene, hornblende and quartz are in the interstices between plagioclase. The matrix is consisted of glass, and micro-crystals of chlorite, epidote and zoisite. It is clearly subjected and extensive alteration. The andesite has an uncommon chemical composition. The SiO_2 content is about 56.8%, TiO_2 = 0.9%, MgO = 6.4%, (Fe_2O_3)_(Total) = 6.7% ~ 7.6%, 100 Mg/(Mg+Fe) = 64.1 ~ 66.2. Mg# is significantly high. The andesite has higher abundances of large-lithophile trace elements (e.g. K, Ba, Sr, LREE), e.g. La/Nd = 5.56-6.07, low abundances of high-strength-field elements (HFSE, e.g. Ta, Nb, P, Ti), particularly Ta and Nb strongly depleted. These are consistent with the characteristics of subducted-related magmas (Pearcce, 1982; Sun and McDonaugh, 1989). In the spider diagram of trace elements, from Ce to right hand, the abundances of elements decrease quickly, showing a characteristic of the continental margins (Pearce, 1982). There has a strongly enrichment of light-rare-earth elements, with a significant diffraction of REEs (the mean value of (La/Yb)_N is 32.84). No Eu anomaly, but there are anomaly high (La/Yb)_N = 28.63-36.74, (La/Y)_N = 70.33 - 82.84. The elements Y and Yb depleted greatly, Y < 20 ppm, Y_N = 2.74-2.84, Yb_N = 2.18 - 2.35. From the La-(La/Sm) diagram, the andesite is derived from partial melting. But the epsilone value of Nd is -18.7 ~ -19.2, so that the material source may be the mantle materials affected by the crustal materials. The Nd model age is 1.9 Ga indicating that the basaltic andesite was resulted from the post-collisional crust-mantle interaction between the subducted Yangze carton and the mantle of Sino-Korea carton. To obtain the Te of the lithosphere beneath the Dabie Mts. and the Hefei Basin, the author applies the coherence method in this thesis. The author makes two topography-gravity profiles (profiles 7~(th) and 9~(th)) across the Dabie Mts. and the Hefei Basin, and calculates the auto-coherence, across coherence, power spectrum, across power spectrum of the topography and gravity of the two profiles. From the relationships between the coherence and the wave-number of profiles. From the relationships between the coherence and the wave-number of profiles 7~(th) and 9~(th), it is obtained that the characteristic wavelengths respectively are 157 km and 126 km. Consequently the values of effective elastic thickness are 6.5 km and 4.8 km, respectively. However, the Te values merely are the minimum value of the lithosphere because the coherencemethod in a relative small region will generate a systemic underestimation. Why there is a so low Te value? In order to check the strength of the lithosphere beneath the Dabie Mts., the authore tries to outline the yielding-stress envelope of the lithosphere. It is suggested that the elastic layers in the crust and upper mantle are 18 km and 35 km, respectively. Since there exist a low viscosity layer about 3-5 km thickness, so it is reasonable that the decoupling between the crust and mantle occurred. So the effective thickness of the lithosphere can be estimated from the two elastic layers. Te is about 34 km. This is the maximum strength of the lithosphere. We can make an approximately estimation about the strength of the lithosphere beneath the Dabie Mts.: Te is about 20-30 km. The author believes that the following factors should be responsible for the low Te value: (1) the Dabie Mts. has elevated strongly since K_3-J_1. The north part of the Dabie Mts. elevates faster than the south part today; (2) there occur large active striking faults in this area. And in the east, the huge Tan-Lu striking fault anyway tends to decrease the lithosphere strength; (3) the lithosphere beneath the Dabie Mts. is heter-homogeneous in spatio-temporal; (4) the study area just locates in the adjacent region between the eastern China where the lithosphere thickness is significantly reduced and the normal western China. These factors will decrease the lithosphere strength.
Resumo:
The Tiezhai intrusive complex is located in the north of the Luxi block, Shandong province, eastern China. It lies ~30 km west of the Tanlu fault, and is at the cross of the Wujing and Jiushan faults. The Tiezhai complex was formed about 120~130 Ma, when large-scale magmatism was active in eastern part of North China. This paper carries out petrochemical and geochemical study on the Tiezhai intrusive complex, and discusses its genesis in detail. The Tiezhai intrusive complex can be subdivided into three rock series. The first is the gabbro-diorite series formed in early stage. Its composition variation shows 01 and Cpx fractional crystallization trend. The second is the porphyritic diorite and monzonite series, showing dominating Hb fractional differentiation. Their composition variation shows Hb fractional crystallization trend. The third is the porphyritic quartz monzonite with K-feldspar megacrysts, showing weakly Hb and Bi fractional crystallization trend. All types of rocks in the Tiezhai complex are belonging to the high-K cac-alkaline series. They have elevated Sr (450-1660 ppm), Ba (210-1780 ppm) and relatively low Rb (30-100 ppm). For the gabbro-dioritic rocks in the early stage, the abundances of Ni (20-250 ppm), Cr (50-350 ppm), V(l30-250 ppm) and Co (20-40 ppm) are high, indicating a mantle origin. All rocks have negative anormalies of Nb, Ta, Ti and P, and enriched LREE and strong differentiated REE patterns. The porphyritic monzonites and quartz monzonites have very low HREE, Yb and Y contents and positive Eu anormalies, similar to adakite. Most rocks have lowε_(Nd)(t) of-1.5~-10.9, and high (~(87)Sr/~(86)Sr)_i of 0.704~0.709. The data have characters of enriched lithosphere mantle (EMI). In summary, the Tiezhai intrusive complex was inferred to be generated by a mantle derived magma through fractional crystallization. When the primary magma gathered in some place between crust and mantle, the crystallization started and causing magma evolution. The remaining / evolved magma ascended and emplaced again and again in the upper crust in Tiezhai area. Then Tiezhai complex formed. The porphyritic monzonites and quartz monzonites have major and trace element characters of typical adakite, but they are likely to be generated by Hb fractional crystallization.