磷化氢在海水中的转化及其影响因素研究

通过室内模拟实验,研究了磷化氢在海水中的转化过程,分析了光照条件、氧化条件、通入方式等环境因子对磷化氢转化的影响。结果表明,在日光照射条件下,磷化氢在海水中可部分转化为磷酸盐,但转化率相对较低,转化过程复杂;环境因子在磷化氢转化过程中起重要作用,日光照射、紫外光照射、氧化条件等均能促进海水中磷化氢向磷酸盐和总磷的转化,在紫外光照射条件下检测到磷化氢向磷酸盐的最大转化率为66.6%。本研究对探索磷化氢在海洋环境生物地球化学循环中的作用具有重要意义。     

The main phosphorous sources in the Changjiang estuary

Analysis using historical data on the phosphate sources in Changjiang （Yangtze River） estuary show that phosphate was supplied equally from the east, south, west and north of the estuary. These sources include the Changjiang River, the Taiwan Warm Current （TWC）, a cyclone-type eddy, and the 32°N Upwelling, supplying different phosphates in different times, ways and intensities. The magnitude of their supplying phosphate concentration was related with the size in the order of the Changjiang River 〈 the TWC 〈 the 32°N Upwelling 〈 the cyclone-type eddy, and the duration of the supplying was： the Changjiang River 〉 the TWC 〉 the cyclone-type eddy 〉 the 32°N Upwelling. The four sources supplied a great deal of phosphate so that the phosphate concentration in the estuary was kept above 0.2 pmol/L in previous years, satisfying the phytoplankton growth. The horizontal and vertical distribution of the phosphate concentration showed that near shallow marine areas at 122°E/31°N, the TWC in low nutrient concentration became an upwelling through sea bottom and brought up nutrients from sea bottom to marine surface. In addition, horizontal distribution of phosphate concentration was consistent with that of algae： Rhizosolenia robusta, Rhizosolenia calcaravis and Skeletonema, which showed that no matter during high water or low water of Changjiang River, these species brought by the TWC became predominant species. Therefore, the authors believe that the TWC flowed from south to north along the coast and played a role in deflecting the Changjiang River flow from the southern side.     

DIETARY PHOSPHORUS REQUIREMENT OF YOUNG ABALONE, HALIOTIS DISCUS HANNAI INO

An experiment was performed to determine the dietary phosphorus requirement of the young abalone,Haliotis discus hannai. Five semi-purified diets were formulated to provide a series of graded levels of dietary total phosphorus (0.23%–1.98) from monobasic potassium phosphate (KH2P04). The brown alga,Laminaria japonica, was used as a control diet. Similar size abalone were distributed in a single-pass, flow-through system using a completely randomized design with six treatments and three replicates each treatment. The abalone were hand-fed to satiation with appropriate diets in excess, once daily at 17:00. The feeding trial was run for 120-d. Survival rate and soft-body to shell ratio (SB/S) were constantly maintained regardless of dietary treatment. However, the weight gain rate (WGR), daily increment in shell length (DISL), muscle RNA to DNA ratio (RNA/DNA), carcass levels of lipid and protein, soft-body alkaline phosphatase (SBAKP), and phosphorus concentrations of whole body (WB) and soft body (SB) were significantly (ANOVA, P<0.05) affected by the dietary phosphorus level. The dietary phosphorus requirements of the abalone were evaluated from the WGR, DISL, and RNA/DNA ratio respectively, by using second-order polynomial regression analysis. Based on these criteria, about 1.0%–1.2% total dietary phosphorus, i.e. 0.9%–1.1% dietary available phosphorus is recommended for the maximum growth of the abalone. Project 39670572 supported by the NSFC.     

秦岭及邻区磷矿成矿问题研讨

秦岭及其邻区地处华北地台南缘、秦岭地槽、松潘 甘孜地块、扬子地台北缘 ,可划分皖鄂、鄂西、陕南、什 (邡 )绵 (竹 )等 4个磷矿密集区。成矿时代自元古宙至泥盆纪 ,以震旦纪、寒武纪为高峰期。矿床以沉积型为主 ,次为沉积变质型及岩浆型。特大型、大型矿床成矿受海盆地控制 ,中、小型矿床则受海沟、海槽或海湾制约。区内可归纳出 3级成矿远景区 ,8个成矿域     

Modelling sediment and total phosphorus export from a lowland catchment: comparing sediment routing methods

Bank erosion is the main source of suspended sediment (SS) and diffuse total phosphorus (TP) in many lowland catchments. This study compared a physically based sediment routing method (Physical method), which distinguishes between stream bed and bank erosion, with the original sediment routing method (Original method) within the Soil and Water Assessment Tool (SWAT) version 2009, for simulating SS and TP losses from a lowland catchment. A SWAT model was set up for the lowland River Odense catchment in Denmark and calibrated against observed stream flow and phosphate (PO₄) loads. On the basis of an initial calibration of hydrological and PO₄ parameters, the SWAT model with the Original method (Original model) and the SWAT model with the Physical method (Physical model) were calibrated separately against observed SS and TP loads. The SWAT model simulated daily stream flow well but underestimated PO₄ loads. The Physical model simulated daily SS and TP better than the Original model. The simulated contribution of bank erosion to SS in the Physical model (99%) was close to the estimated contribution from in situ erosion measurements (90–94%). Compared with the Original method, the Physical method is not only more conceptually correct but also improves model performance. Copyright © 2014 John Wiley & Sons, Ltd.     

海水溶解磷酸盐氧同位素组成的测定

生物磷酸盐和水分子间的氧同位素分馏主要受温度和生物活动控制, 因此磷酸盐氧同位素组成既可以测量古温度又可以示踪磷循环。近年来磷酸盐氧同位素研究受到较多关注, 除了传统的生物体磷灰石古温度测量外, 这些研究大多是关于磷循环的。磷酸盐的氧同位素组成可以示踪海洋中磷的源区和生物对磷的利用效率。由于海水的组成十分复杂, 测量前必须对样品进行富集、分离和纯化处理。目前, 加州大学(Santa Cruz)Paytan教授和耶鲁大学Blake教授的实验室已建立了海水溶解磷酸盐氧同位素的测量方法, 二者各有优缺点。我们结合了这两种方法的优点, 并对一些步骤进行了改进, 建立了海水溶解磷酸盐氧同位素组成的测量方法。通过向海水样品中加入NaOH, 形成Mg(OH)2来富集海水中的PO43-, 也可同时除去部分杂质离子和溶解有机质; 通过将PO43-转化为CePO4沉淀来进一步除去杂质离子, 然后用阳离子交换树脂除Ce3+, 再通过阴离子交换树脂柱来除溶解有机质。最后将磷酸盐转换为Ag3PO4沉淀, 在1350℃裂解Ag3PO4, 产生的O2和石墨反应形成CO用IRMS测定。结果显示富集、分离和纯化过程可以获得纯的Ag3PO4颗粒, 不会产生PO43-的氧同位素分馏。测量Ag3PO4用量仅为0.3 mg, 标准偏差在±0.2‰~±0.3‰之间。     

电感耦合等离子体发射光谱法测定磷矿石中常量元素硅磷硫钙镁铝铁钛锰

以粒状氢氧化钠作熔剂,样品在银坩锅中700℃熔融,热水浸取后用盐酸酸化,溶液冷却定容后直接用电感耦合等离子体发射法测定磷矿石中硅、磷、硫、钙、镁、铝、铁、钛、锰9种常量元素,采用基体匹配和离峰扣背景等方式有效消除了测定的干扰。对样品分解条件、试剂用量、元素分析谱线的选择、干扰的影响及消除等进行了优化处理和讨论。方法精密度(RSD)为0.28%～1.85%(n=12),回收率为97.92%～107.1%,具有快捷、成本低等特点。经国家一级标准物质分析验证,结果满意,适用于磷矿石中常量元素的快速分析。     

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。     

摩尔配比和矿物掺合料对盐湖提锂镁渣制作磷酸钾镁水泥性能影响的研究

使用盐湖提锂镁渣和矿物掺合料,如粉煤灰、硅灰和矿渣等,与磷酸二氢钾反应,制作磷酸钾镁水泥(Magnesium Potassium Phosphate Cement,MKPC)。研究了MgO/KH₂PO₄摩尔配比(M/K)和矿物掺合料对MKPC凝结时间、抗压强度和水化放热速率的影响,并使用X射线衍射(X-ray diffraction,XRD)和低真空扫描电子显微镜(Scanning Electron Microscopy,SEM)分析MKPC的水化产物。研究表明,M/K对MKPC抗压强度影响显著,最佳M/K为4~6。M/K为5时,MKPC在各龄期的抗压强度值均较高,28d抗压强度高达98MPa。掺加矿物掺合料会降低MKPC的抗压强度,当粉煤灰、硅灰和矿渣的掺量分别为水泥质量的20%,10%和20%时,28d抗压强度可以分别达到45.9MPa、33.3MPa和36.7MPa。凝结时间超过20min,能够满足快速修复的要求。在不考虑Mg₃B₂O₆的影响下,掺加矿物掺合料会延缓MKPC凝结时间和降低放热速率。