Henry's law constant and hydrolysis of peroxyacetyl nitrate (PAN)

The effect of temperature on the solubility of PAN and on its hydrolysis rate in near-neutral and slightly acidic water were studied in a bubble column apparatus. The results obtained are a Henry's law coefficient H=10^–9.04±0.6 exp[(6513±376)/T] M atm^–1, and a first-order hydrolysis rate constant k=10^6.60±1.0 exp[(–6612±662)/T] s^-1, which was independent of pH in the range 3.2pH6.7. The products formed are nitrite and nitrate in approximately equal proportions under near-neutral conditions. At a pH<4, nitrite is oxidized in a secondary reaction, and nitrate becomes the only product at low pH. Previously measured deposition velocities of PAN on stagnant water surfaces are shown to be hydrolysis rate limited.     

Alkyl nitrates and bifunctional nitrates of atmospheric interest: Henry's law constants and their temperature dependencies

Henry's law coefficients of 15 alkyl nitrates, keto-, hydroxy-, and dinitrates of atmospheric interest have been measured, mostly over the temperature range 1–25°C. The compounds are stable in aqueous solution. Where literature data were available, Henry's law coefficients are in very good agreement. It is concluded that dissolution in cloud and rain water is not an important loss process for alkyl mononitrates in the atmosphere. The residence times of the more soluble bifunctional organic nitrates, however, are significantly affected or even controlled by washout and rainout. Gas chromatographic analysis of bifunctional nitrates in preconcentrated atmospheric samples may be adversely affected by the adsorptive properties of these compounds.     

卧龙饮用含硅矿泉水化学成分的成因

地下水是一种化学成分复杂的物理化学体系。本文从化学热力学和元素地球化学的角度出发,对卧龙饮用含硅矿泉水的化学成分的成因及锶的来源进行了探讨。     

Characterization of soil humin by acid hydrolysis

Studies were conducted to characterize soil humin by acid hydrolysis.Two humin samples collected from two different types of soil,namely chernozem and laterite,which are widespread over a vast area from the north to south of China,were hyrolyzed under reflux with 0.5M H2SO4or 3M H2SO4for 4h.The results showed that 25%-29% of organic carbon and 46%-54%of organic nitrogen could be hydrolyzed by 0.5M H2SO4;36%-40%of organic carbon and 93%-97% of organic nitrogen hydrolyzed by 3M H2SO4.The C/N ration in hydrolyzed organic matter is lower than that in soil humin and that in organic matter hydrolyzed by 3M H2SO4 is lower than that in organic matter hydrolyzed by 0.5M H2SO4.The proportion of nitrogen hydrolyzed from humin is markedly larger than that from the original soil and also markedly larger than that from humic acid fraction.Only 3%-7% of nitrogen in humin exists in a relatively stable from,which is not easy to hydrolyze.There in little nitrogen that occurs in the form of heterocyclic rings in humin.Incubation experiments showed that the newly formed organic matter can be hydrolyzed more easily.     

酶法制备几丁寡糖和壳糖研究现状与进展

对用酶法制备几丁寡糖和壳寡糖研究现状与进展进行了综述。几丁质酶、壳聚糖酶、溶菌酶和 N-乙酰葡萄糖胺酶等专一性的水解酶及糖酶、蛋白酶、脂肪酶等水解酶对几丁质和壳聚糖都具有部分或完全非专一性水解作用。介绍了这些酶类的作用机理及相关微生物的种类和作用条件     

云贵高原湖泊沉积物中的色氨酸及其地球化学行为

利用碱性水解—高效液相色谱联用技术测定了云贵高原四个湖泊沉积物中色氨酸的含量。讨论了色氧酸的早期成岩作用并与其它氨基酸进行比较。利用优化的碱性水解条件(120℃、4．2MNaOH溶液中水解20h)分析沉积物中的色氧酸含量,回收率达93％。实验结果显示,在所研究的四个湖泊沉积物中,色氨酸只是一种微量氨基酸组分,浓度为0．15～2．66μmol／g,占总可水解态氨基酸的0．17％～9．18%。色氨酸的相对摩尔百分含量随沉积深度的增加呈上升趋势,与其它两种芳香性氨基酸酪氨酸和苯丙氨酸的变化趋势相反,揭示了芳香性氨基酸在早期成岩过程中的地球化学行为。研究结果还表明,色氨酸在沉枳物早期成岩过程中被硅藻细胞壁选择性保存。     

Alkaline phosphatase activity of water column fractions and seagrass in a tropical carbonate estuary, Florida Bay

Few phosphorus-depleted coastal ecosystems have been examined for their ability to hydrolyze phosphomonoesters. We examined seasonal (August 2006–April 2007) alkaline phosphatase activity in Florida Bay, a phosphorus-limited shallow estuary, using fluorescent substrate at low concentrations (≤2.0 μM). In situ dissolved inorganic and organic phosphorus levels and phosphomonoester concentrations were also determined. Water column alkaline phosphatase activity was partitioned into two particulate size fractions (>1.2 and 0.2–1.2 μm) and freely dissolved enzymes (<0.2 μm). Water column alkaline phosphatase activity was also compared to leaf and epiphyte activity of the dominant tropical seagrass Thalassia testudinum. Our results indicate: (1) potential alkaline phosphatase activity in Florida Bay is high compared to other marine ecosystems, resulting in rapid phosphomonoester turnover times (2 h). (2) Water column alkaline phosphatase activity dominates, and is split equally between particulate and dissolved fractions. (3) Alkaline phosphatase activity was highest during cyanobacterial blooms, but not when normalized to chl a. These results suggest that dissolved, heterotrophic and autotrophic alkaline phosphatase activity is stimulated by phytoplankton blooms. (4) The dissolved alkaline phosphatase activity is relatively constant, while the particulate activity is seasonally and spatially dynamic, typically associated with phytoplankton blooms. (5) Phosphomonoester concentrations throughout the bay are low, even though potential hydrolysis rates are high. We propose that bioavailable dissolved organic P is hydrolyzed by dissolved and microbial alkaline phosphatase enzymes in Florida Bay. High alkaline phosphatase activity in the bay is also promoted by long hydraulic residence times. This background activity is primarily driven by carbon and phosphorus limitation of microorganisms, and regeneration of enzymes associated with cell lysis. Pulses of inorganic phosphorus and labile organic phosphorus and nitrogen may stimulate autotrophs, particularly cyanobacteria, which in turn promote biological activity that increase alkaline phosphatase activity of both autotrophs and heterotrophs in the bay.     

6-O-羧甲基氨基葡萄糖的制备及其结构分析

采用酶降解和酸降解相结合的工艺,将大分子量的6-O-羧甲基甲壳素降解成单分子的6-O-羧甲基氨基葡萄糖,经906型弱碱性阴离子交换树脂柱吸附层析分离,制得羧甲基化氨基糖。对该单糖进行了HPLC、高效薄层、比旋光度、熔点和红外光谱等方面的分析研究。结果表明,该单糖在C6连有羧基,C2连有氨基,具有特定的比旋光度和熔点特征,与报道的结果相一致。     

酶解蓝圆鲹鱼肉蛋白制备小分子肽的工艺研究

以蓝圆鲹为原料,酶解蓝圆鲹鱼肉蛋白制备小分子肽。运用响应面试验设计优化蓝圆鲹蛋白酶解的工艺条件,探讨了酶种类和添加量、液固比、酶解温度、酶解时间对多肽提取率的影响。结果表明:选用木瓜蛋白酶,添加量为0.10%,液固比2∶1,酶解温度54.4℃,酶解时间3.18 h下,多肽提取率为32.35%。     

广域电磁法在洞庭盆地北部生物气勘探中应用及远景靶区预测

洞庭盆地地处湘西古生界边缘,经历了中生代晚白垩世盆地基本成型和新生代断块运动为主的两期构造旋回,为终成于燕山(中生代)延续于喜马拉雅(新生代)的断陷盆地。盆内局部凹陷白垩系之上存在着持续砂泥岩沉积及第四纪河流湖泊相现代沉积,具备了形成一定规模生物气藏的地质条件。2013-2015年笔者通过洞庭盆地浅层沉积物系统地球化学勘探,基本搞清了盆地内渗漏甲烷气体异常的分布状况。根据各指标地球化学异常特征,发现洞庭盆地北部沅江凹陷北部斜坡、青树嘴-河坝镇一带是洞庭盆地内生物气资源最有可能突破的远景区。为了追索渗漏甲烷气体来源,深化地球化学异常解释评价以及浅层生物气系统研究,2015-2016年在发现的生物气远景区,部署完成5条广域电磁测深和两条汞气测量剖面。本研究旨在通过实测地球物理和地球化学综合剖面的对比研究,揭示本区第四系构造分布和地球化学异常机制,为洞庭盆地生物气资源远景和气藏靶区的预测划分提供科学依据,也为勘探第四系生物气资源方法技术的选择提供了建议。勘探成果表明：(1)本区第四系能够满足生物气系统“生储盖”条件,具有生物气资源潜力;(2)沉积物游离烃甲烷地球化学异常是下伏第四系内气体聚集沿断裂带或沉积层向表层渗漏运移所致。酸解烃指标是识别有利于生物气体生储环境的敏感因子之一;(3)洞庭盆地工区西北部,P2剖面南段和P2线北部与P3、P4剖面交汇区域,具有良好的“自生自储”型生物气藏资源远景,是本区勘探生物资源天然气最有希望的靶区;(4)洞庭湖北部工区东部,P6测线南部接近沅江凹陷中心的四季红一带,是本区寻找 “自生自储”和“下生上储”型气藏的有利地带和资源远景区;(5)浅层沉积物地球化学勘探,有利于发现与生物气有关的气体渗漏、评价下伏沉积体系特性、缩小地球物理勘探靶区。地球化学与广域电磁剖面测量的结合是勘探生物成因天然气经济快速的方法技术。