Authigenesis of vivianite as influenced by methane-induced sulfidization in cold-seep sediments off southwestern Taiwan

Authigenesis of iron-rich phosphate nodules occurs in iron-rich cold-seep sediments (MD052911 core) at Yung-An Ridge offshore southwestern Taiwan. Raman, FTIR, and quantitative X-ray energy-dispersive spectroscopic analyses indicate that the phosphate mineral is vivianite (or barićite) and shows Fe/Mg molar ratios spanning from ca. 0.6 to 4.0 and a general down core trend of increasing Fe/Mg ratios. The formation of vivianite is limited to a depth interval of 13–17 mbsf (meters below seafloor) and is most prominent at ∼16 mbsf in association with high dissolved iron concentrations and depleted dissolved sulfide below a peak sulfidization zone (enriched in mackinawite and greigite). Alternate growths of vivianite and iron monosulfides and compositional zoning with Mg enriched towards the peripheries of individual nodules occur in the transition from the zone of vivianite mineralization to the sulfidization zone. The crystallization of vivianite below the sulfidization front could have been favored by scavenging of downward diffusive dissolved sulfide from pore waters in the sulfidization zone. Alternate growths and overlapping of the zones of iron monosulfides and vivianite can be attributed to fluctuations of the sulfidization front and methane flux. The discovery of vivianite in the Yung-An Ridge sediments implies that authigenic vivianite can be an important sink for phosphorus burial in cold-seep sediments that have high reactive-iron contents and high sedimentation rates.     

旅游活动对黄龙景区磷酸盐浓度和水藻生长的影响

由于其独特的钙华景观,黄龙风景区从1992年被联合国教科文组织列入世界自然遗产名录以来,每年吸引数以十万甚至百万计的国内外游客前来游览;然而,可能由于旅游活动的影响,近年来黄龙钙华景观出现了诸多形式的退化,水藻加速生长钙华黑化即是其表现形式之一。为了阐明这一退化现象是否与旅游活动有关,从2010年5月底到11月初的丰水时段,采用野外自动监测和室内分析相结合的方法,对溪流水藻叶绿素含量和水中的磷酸盐浓度变化进行了研究。结果发现,随着景区游客人数的增减,水中磷酸盐浓度呈现出与之一致的变动趋势;同时,叶绿素与磷酸盐间也呈现出明显一致的变动趋势。因此,我们认为,旅游活动增加了黄龙景区的磷酸盐浓度,并促进了水藻的生长,这很可能是黄龙水藻近年来加速生长的重要原因,值得引起有关方面的高度关注。     

较低稀释比熔片制样X射线荧光光谱法测定磷矿石中12种主次痕量组分

当前应用X射线荧光光谱熔片制样技术分析测定较低含量、低荧光产额氟组分时,准确度较低,精密度较差、检出限较高。本文运用5:1较低稀释比熔样制片技术,采用波长色散X射线荧光光谱法测定磷矿石中12个主次量组分(F、Na₂O、MgO、Al₂O₃、SiO₂、P₂O₅、K₂O、CaO、TiO₂、MnO、TFe₂O₃和痕量SrO)。采用磷矿石、岩石国家一级标准物质、磷矿石管理样品和人工配制标准样品校准,经验系数法进行基体校正,结果表明12个组分分析方法的精密度和准确度较好,检出限较低,未知样品的分析结果比较满意;氟的精密度、准确度和检出限均好于文献中10:1熔样稀释比得出的结果。该方法解决了压片制样测定氟组分,熔片制样测定其他主次量组分的技术问题,同时也降低了熔片制样技术测定氟的检出限。     

贵州省磷矿品位-吨位模型的建立及其地质意义

利用2009年贵州省矿产资源利用现状调查磷矿成果数据库,以核查块段为基础,通过块段品位和块段资源储量数据对全省磷矿核查矿区平均品位统计,掌握了全省核查矿区高中低品位磷矿石的分布,并对块段品位数据区间分段统计吨位频率,建立了寒武系磷矿层和震旦系磷矿层品位-吨位模型。统计结果表明,寒武系磷矿层的矿区平均品位总体较低,震旦系磷矿层矿区平均品位总体较高,全省磷矿吨位频率服从正态分布,寒武系磷矿层吨位峰值区间较窄,震旦系磷矿层吨位峰值区间较宽。综合研究表明,开阳-息烽片区和瓮安-福泉片区震旦系磷矿层高品位矿石资源储量多,矿石质量好,可作为全省磷矿资源开发利用布局的重点地区,铜仁-松桃片区和清镇-织金片区寒武系磷矿层品位低、贫矿石资源储量多,矿石质量差,应加强低品位矿石和贫矿石的选矿技术研究。     

贵州省织金县新华含稀土磷矿矿床地质特征及成因探讨

贵州织金新华含稀土磷矿床产于早寒武世梅树村阶底部含磷岩系中(上磷矿层),磷矿伴生的稀土REO含量达333.45×10-6～974.15×10-6,平均640×10-6,为含稀土磷块岩沉积矿床。通过对新华含稀土磷矿矿床的成矿地质背景、地质特征的研究,从岩相古地理、生物成矿基本特征、稀土元素物质来源、成矿作用、成矿模式等矿床成因进行的探讨,初步认为织金新华含稀土磷矿床严格受地层、岩相古地理的控制。     

不同温度下脉冲式磷酸盐输入对裸甲藻生长的影响

脉冲式输入营养盐是陆源向海洋输入营养盐的一种重要方式。本文在实验室条件下,模拟脉冲式磷酸盐输入的方法,研究不同温度下磷酸盐脉冲输入对裸甲藻(Gymnodinium sp.)生长的影响。结果发现:10℃低温条件下,低质量浓度磷酸盐脉冲试验中,每天输入一次的脉冲方式下裸甲藻的长势在一段时间段内占据优势,但整体来看,差异并不显著;高质量浓度磷酸盐脉冲试验中,每8天输入一次的脉冲方式下藻的长势占据明显优势,差异显著(P0.05)。而在25℃常温条件下,无论是低质量浓度脉冲组还是高质量浓度脉冲组,基本表现为1天输入一次的脉冲方式下的裸甲藻藻密度都占有较明显优势(低质量浓度组P0.01;高质量浓度组P0.01)。不管在低温或常温下,在所有实验组中,脉冲频率对裸甲藻的影响基本表现为:在中等频率的磷酸盐脉冲下,藻密度最低。     

Response of Microbial Community to Petroleum Stress and Phosphate Dosage in Sediments of Jiaozhou Bay,China

The dynamic microcosms were used to evaluate the effect of oil spills on microbial ecological system in marine sedi- ment and the enhancement of nutrient on the oil removal. The function and structure of microbial community caused by the oil pollu-tion and phosphate dosage were simultaneously monitored by dehydrogenase activity assay and PCR-denaturing gradient gel elec- trophoresis （DGGE） techniques. The results indicated that the amount of total bacteria in all dynamic microcosms declined rapidly with incubation time. The number of petroleum-degrading bacteria and the activity of sediment dehydrogenase were gradually en-hanced by petroleum in the oil-treated microcosms, while they both showed no obvious response to phosphate dosage. In comparison, phosphate spiked heterotrophic bacteria and they showed a significant increase in amount. DGGE profiles indicated that petroleum dosage greatly changed community structure, and the bacteria belonged to class Deltaproteobacteria, and phyla Bacteroidetes and Chlorobi were enriched. This study demonstrated that petroleum input greatly impacted the microbial community structure and con- sequently the marine sediment petroleum-degrading activity was enhanced. Phosphate dosage would multiply heterotrophic bacteria but not significantly enhance the petroleum degradation.     

Dissolved Nutrient Distributions in Groundwater in the Mediterranean Coastal Plains – the Case of Silifke,Turkey

Total carbon, nitrogen, and phosphate parameters were studied for the first time in the groundwater in the Silifke coastal plain, which is a RAMSAR site in Turkey. Seasonal variations of these parameters in the plain were examined based on groundwater data collected from 21 wells during the winter, spring, summer, and fall seasons. Total dissolved organic carbon (DOC), inorganic carbon (DIC), inorganic phosphate (DIP), inorganic nitrogen (DIN), and total alkalinity (TAlk) average values in the groundwater were low in all seasons (<2.2 mg/L for DOC; <54 mg/L for DIC; <0.06 mg/L for DIP; <1.5 mg/L for DIN; <232 mg/L for TAlk). The results showed a strong relationship between DIC and as expected. The results indicate that the content of these parameters in the groundwater of Silifke coastal plain pose no or little risk at present. However, computed Langelier Saturation Index (LSI) values indicated that the groundwater has a tendency to form scale and CaCO₃ precipitation may occur.     

磷酸铝结合剂改性绿松石的结构特征

疏松绿松石经磷酸铝结合剂浸胶充填处理后,宝石学参数、力学和工艺性质均得到明显改善,与天然绿松石相仿.为查明这类改性绿松石的结构和探讨磷酸铝无机结合剂对绿松石的改善机理,采用环境扫描显微镜(ESEM)、差热分析(TG-DSC)、红外吸收光谱(IR)和X射线粉晶衍射分析方法(XRD),对此类浸胶充填处理后的绿松石结构、物相及热性质等特征进行了研究.结果显示充填入的磷酸铝结合剂呈凝胶状分布在绿松石微孔隙间,处理后绿松石的分子结构和矿物组构与处理前一致,但产生了一定程度的非晶质化,与磷酸铝结合剂的填充作用有关,即磷酸铝结合剂在固化过程中生成氢,结合形成无机网络高分子结构;处理后绿松石的热反应温度较处理前普遍有所降低,主要是由于添加入的磷酸铝结合剂具有较低的吸热反应温度所致.      

The inhibitory degree between Skeletonema costatum and dinoflagllate Prorocentrum donghaiense at different concentrations of phosphate and nitrate/phosphate ratios

Interactions between Skeletonema costatum (S. costatum) and Prorocentrum donghaiense (P. donghaiiense) were inves-tigated using bi-algal cultures at different concentrations of phosphate (PO4-P) and nitrate/phosphate (N/P) ratios. Experiments were conducted under P-limited conditions and the Lotka-Volterra mathematical model was used to simulate the growth of S. costatum and P. donghaiense in the bi-algal cultures. Both of these two species were inhibited significantly in bi-algal culture. The results of the simulation showed that the inhibitory degree of S. costaum by P. donghaiense was high when the concentration of PO4-P was low (0.1μmolL-1/2 d), but that of P. donghaiense by S. costaum was high with increased PO4-P supply (0.6μmolL-1/2 d). At low concen-tration of PO4-P (0.1μmolL-1/2 d), or high concentration of PO4-P (0.6μmolL-1/2 d) with high N/P ratio (160), the interactions be-tween S. costatum and P. donghaiense were dependent on the initial cell densities of both species. At high concentration of PO4-P (0.6μmolL-1/2 d) with low N/P ratio (25 or 80), S. costatum exhibited a survival strategy superior to that of P. donghaiense. The de-gree of inhibition of P. donghaiense by S. costaum increased with elevated N/P ratio when the medium was supplemented with con-centration 0.1μmolL-1/2 d of PO4-P. The degree of inhibition to P. donghaiense by S. costaum increased with elevated N/P ratio at low concentration of PO4-P (0.1 μmolL-1/2 d). This trend was conversed at high concentration of PO4-P (0.6μmolL-1/2 d). However, the degree of inhibition of S. costaum by P. donghaiense increased with the increased N/P ratio at different PO4-P concentrations (0.1μmolL-1/2 d and 0.6μmolL-1/2 d). These results suggested that both phosphate concentration and N/P ratio affected the competition between S. costaum and P. donghaiense: P. donghaiense is more competitive in environments with low phosphate or high N/P ratio and the influence of N/P ratio on the competition was more significant with lower phosphate concentration.