Combined effects of light intensity and NH^＋4-enrichment on growth,pigmentation, and photosynthetic performance of Ulva prolifera （Chlorophyta）

The aim of this study was to investigate the effects of light intensity and enhanced nitrogen supply on the growth and photosynthesis of the green-tide macroalga, Ulva prolifera. Thalli of U. prolifera were grown in natural or NH 4 +-enriched seawater under two different light intensities for 7 days, and then the growth rate, pigmentation, and photosynthetic performance of the thalli were evaluated. The results show that the relative growth rate(RGR) was markedly higher under the high light level than under the low light level. Enrichment with NH 4 + enhanced the RGR under high light intensity, but did not affect RGR under low light intensity. In low light conditions, NH 4 +-enrichment resulted in a marked decrease in the maximal photosynthetic rate( P m) and the maximum carbon fixation rate( V max), but it did not affect the half saturation constant for carbon( K 0.5) or the ratio of V max to K 0.5, which reflects the carbon acquisition efficiency. In high light conditions, P m, K 0.5, and the dark respiration rate( R d) increased under NH 4 + enrichment, but V max and the V max / K 0.5 ratio decreased. Regardless of the light intensity, NH 4 +-enrichment did not affect the apparent photosynthetic efficiency( α), which refl ects the ability of the alga to use light energy at low light levels. Under both low and high light intensities, the chlorophyll a(Chl a), chlorophyll b(Chl b), and carotenoids(Car) contents in thalli were higher in NH 4 +-enriched than in natural seawater, except that there was a decrease in the Chl b content of thalli in NH 4 +-enriched seawater under low light intensity. Therefore, NH 4 + enrichment improved the growth and photosynthetic performance of U. prolifera under high light intensity, but not under low light intensity. We discuss the possible mechanisms underlying these physiological responses.     

Evaluation of the biological toxicity of fluorine in Antarctic krill

Antarctic krill is a potentially nutritious food source for humans, but fluorine(F) toxicity is a matter of concern. To evaluate the toxicity of F in Antarctic krill, 30 Wistar rats were divided into three groups with different dietary regimens: a control group, a krill treatment group(150 mg·kg-1 F), and a sodium fluoride(NaF) treatment group(150 mg·kg-1 F). After three months, F concentrations in feces, plasma, and bone were determined, and the degree of dental and skeletal fluorosis was assessed. The F concentrations in plasma and bone from the krill treatment group were 0.167 0±0.020 4 mg.L-1 and 2 709.8±301.9 mg·kg-1, respectively, compared with 0.043 8±0.005 5 mg·L-1 and 442.4±60.7 mg·kg-1, respectively, in samples from the control group. Concentrations of F in plasma and bone in the krill treatment group were higher than in the control group, but lower than in the NaF treatment group. The degree of dental fluorosis in the krill treatment group was moderate, compared with severe in the NaF treatment group and normal in the control group. The degree of skeletal fluorosis did not change significantly in any group. These results showed that the toxicity of F in Antarctic krill was lower than for an equivalent concentration of F in NaF, but it was toxic for rats consuming krill in large quantities. To conclude, we discuss possible reasons for the reduced toxicity of F in Antarctic krill. The present study provides a direct toxicological reference for the consideration of Antarctic krill for human consumption.     

Are assemblages of the fireworm Hermodice carunculata enhanced in sediments beneath offshore fish cages?

Abundances of the fireworm Hermodice carunculata were counted through a monitoring assessment study of fish cages in Barranco Hondo（NE Tenerife）. Seven campaigns were conducted from November 2007 to June 2010 and temporal variations were found, as well as differences among sampling stations. The polychaete H. carunculata obtained its highest abundance in sediments beneath fish cages throughout the study period. Thus, the assemblages of this omnivorous species were favoured by the presence of fish cages.     

Distribution and sources of heavy metals in the sediment of Xiangshan Bay

Heavy metals in the surface sediments and sediment core from the Xiangshan Bay, a mariculture base on the coast of the East China Sea, were determined by inductively coupled plasma mass spectrometry(ICP–MS) in order to evaluate their levels and sources. The results showed that the levels of Cu, Pb, Zn, and Cr in the sediments of the bay have been generally influenced by anthropogenic inputs since the founding of the People's Republic of China. In particular, Cu and Zn were polluted to some extent, as evidenced by high enrichment factors. Organic matter, grain size, wastewater discharge, and low energy hydrodynamic environment played dominant roles in the heavy metal enrichment in the sediments. The ratio of terrigenous source to marine biogenic deposit of trace metals in the sediments was calculated, revealing that terrigenous inputs were the main source of Cu, Pb, and Zn, while biological pellets contributed much more to the enrichment of Cr and Cd. Considering the influence of biological sources on the enrichment of Cd and Cr, and the fact that the sediment has been polluted by Cu and Zn, the development of mariculture and discharge of wastewater into the Bay should be restricted.     

张家口市坝下山区岩溶水的富集规律研究

张家口市坝下地区位于河北省西北部,水文地质情况较复杂,区内碳酸盐岩地层分布较广,地下裂隙岩溶水资源较丰富。根据相关水文地质资料,分析总结了可溶岩地层的厚度、岩性及岩性组合、分布面积、地质构造及地形条件等因素对岩溶水富集规律的影响和控制,阐明了区内岩溶水的供水意义。     

太平洋富钴结壳中碲元素的地球化学特征及其富集机制探讨

文章通过对采自太平洋海域不同海山上68个结壳样品中Te元素地球化学特征的研究,探讨了富钴结壳中控制Te元素富集的古海洋氧化还原环境及其富集机制。分析表明,太平洋海域中大多数结壳的w（Te）变化于13.4×10^-6~115.8×10^-6,平均50×10^-6,是海水w（Te）的10⁹倍;结壳中w（Te）与Mn/Fe比值呈正相关,相关系数为0.51;与Fe呈负相关,相关系数为-0.61,显示结壳中Te与Co有类似的地球化学特征。古海水氧化还原环境的改变是控制结壳中Te元素含量变化的重要因素;能反映古海水氧化还原环境的Ce异常与结壳中Te含量基本呈同步变化趋势,Te含量具有随古海水氧化程度减弱而降低的特征。结壳中Te元素的富集主要受控于其内的Mn/Fe比值。Te元素的富集机制除被海水中带微弱正电荷的FeOOH胶体以库伦静电吸附外,还可能与δ-MnO₂表面上以一种表面络合物方式的富集机制有关。Te进入结壳的存在形式及其在不同古海洋环境中的富集机制还有待进一步研究和探讨。     

马超营断裂带地质及地球化学特征

根据对马超营断裂带系统进行的地质—地球化学剖面研究，探讨了该带断裂构造活动及其元素地球化学迁移富集规律与构造地球化学分异之间的关系；分析了蚀变、矿化与成矿的关系，认为早期面型蚀变伴有成矿元素的活化和迁移，但无矿化富集，后期带状蚀变伴有金的富集成矿且以硅化、绢云母化为主要标志。从而，为马超营断裂带这一重要的以金为主成矿带的进一步工作、研究，提供了地球化学方面的依据。     

贵州盘州米妥勘查区煤层顶底板Ga矿富集特征及成因

为查清贵州盘州米妥勘查区煤层顶底板及煤中Ga的赋存状况,开展钻孔勘探工作,采集煤层顶底板泥化样品39件,煤样品25件,使用电感耦合等离子体发射光谱法测定Ga含量,根据样品中Ga含量的实测结果,结合勘查区聚煤时期的古地理环境及煤层顶底板沉积物源等特征,分析上二叠统煤层顶底板中Ga矿的富集特征及成因。结果表明：米妥勘查区煤中Ga富集程度低,25件煤样品中Ga的平均含量为7.90 μg/g,远低于边界品位;煤层顶底板中Ga富集程度高,21件顶板样品中Ga含量为31.8～46.2 μg/g,平均值为39.6 μg/g,18件底板样品中Ga含量为31.1～51.4 μg/g,平均值为41.3 μg/g,底板中Ga含量均值略高于顶板。顶底板中Ga的含量达到我国煤中伴生矿的工业指标,该区域煤层顶底板及围岩具有稀散金属矿找矿前景。分析沉积的古地理环境特征及沉积物源,认为聚煤时期古地理环境多为陆相及海陆交互相,导致煤层顶底板多为泥岩及泥质砂岩,陆源碎屑物为Ga沉积提供了很好的来源,流水、风力等搬运作用为Ga提供了很好的富集方式。     

我国陆相中高熟页岩油富集条件与分布特征

我国相继在多个盆地陆相页岩油勘探中获得突破,展示了良好的发展前景。基于现阶段勘探认识,本文认为陆相页岩油富集主要条件是：(1)稳定且有规模和适宜热成熟度的富有机质页岩是重要物质基础,以TOC含量>2%,最佳为3%～4%、母质类型Ⅰ和Ⅱ₁型为主,R_o>0.9%或更高(咸化环境0.8%);(2)有一定容积规模的微纳米孔隙且具脆性的多类储层是重要条件,页岩储层有效孔隙度宜>3%～6%;成岩阶段偏低时,纯页岩段不是中高熟页岩油富集段,致密砂岩和混积岩黏土含量宜<20%;成岩阶段高时,页岩黏土含量可高至40%左右;(3)滞留烃数量大且品质好是重要保证,以S₁>2 mg/g为门限,最佳>4～6 mg/g;气油比>80 m³/m³,最佳150～300 m³/m³;(4)顶底板具封闭性保持超压且滞留足够多轻-中组分烃类。陆相页岩油分布特征是：(1)有外物质注入的深-半深湖相是页岩油主要富集区;(2)具备“四高...     

钒矿床研究进展与展望

钒是工业国家重点关注和争夺的资源,已被部分国家列为关键金属。本文对矿床类型、地质特征、时空分布以及成矿机制等方面进行了系统总结和分析,以期丰富钒成矿理论研究,为提高钒资源的预测和勘查效率提供支撑,为钒资源储备提供保障。研究发现,钒矿床主要分为岩浆型和沉积型,其中岩浆型钒矿床（主要指钒钛磁铁矿床）成矿与铁镁质–超铁镁质岩及部分斜长岩侵位密切相关,成矿年龄与成岩年龄一致,钒可能来自上地幔并在岩浆演化过程中结晶析出赋存于含钒钛磁铁矿中;沉积型钒矿床多形成于黑色岩系及部分砂岩中,成矿多集中于上寒武世,钒可能来自海水和赋矿围岩,由于氧化还原电位降低,以吸附和类质同象等形式赋存于有机质和硅酸盐矿物中。同时,钒矿床的成因研究存在较多问题,如成矿物质钒的来源、迁移过程、赋存形式及富集条件等。笔者建议在今后研究中通过分析钒化学行为、围岩沉积物理–化学–生物条件及岩浆演化的地质动力背景来解析钒矿床成因机制。