An Examination of the Oxidation of Elemental Mercury in the Presence of Halide Surfaces

Recent field investigations in polar regions, and over the ocean, have suggested that elemental mercury (Hg⁰) can be photochemically oxidized in the presence of reactive halogen species that are formed in the presence of salt particles, typically through a reactive catalytic cycle involving ozone destruction. Furthermore, these studies have suggested that the Hg⁰ oxidation reaction involves the reaction with reactive bromine species such as Br, BrO, and Br₂. To investigate these reactions in more detail, we performed experiments using a quartz reactive chamber so that the oxidation of Hg⁰, and the formation of ionic Hg products, could be examined in detail under different reaction scenarios, but at realistic levels of Hg. To examine if the reactions were enhanced by the presence of deliquescent salt surfaces, as has been postulated to be the case for the formation of reactive halogens, one surface of the cell was coated with either NaCl or NaBr for some experiments. In addition to laboratory experiments with a Xenon lamp, outdoor experiments under natural light were also conducted. The results of these studies showed that oxidation of Hg⁰ did not occur in the dark, except in the presence of a deliquescent NaBr salt surface. The rate of oxidation was slow in the absence of salt surfaces, and in the absence of low wavelength light (<324 nm). In the presence of NaCl surfaces, oxidation rates were at least two orders of magnitude faster, but the rate was further increased in the presence of NaBr, by a further factor of 25. With outdoor light, while the rates of oxidation were lower, the results were similar overall. The results are discussed in terms of the reactions occurring and the mechanisms of Hg⁰ oxidation. Finally, the implications of these reactions to the overall global Hg cycle are discussed.     

等离子体发射光谱法测定重晶石中钡铁和硅

重晶石经Ｎａ２ＣＯ３熔融,水浸取,过滤。沉淀经ＨＣｌ溶解后,用电感耦合等离子体发射光谱法同时测定主成分ＢａＳＯ４和次量成分Ｆｅ２Ｏ３以及滤液中的ＳｉＯ２,结果与部颁标准方法符合。方法精密度好,主量组分ＢａＳＯ４测定的ＲＳＤ（ｎ＝６）为０．２４％,次量组分Ｆｅ２Ｏ３和ＳｉＯ２的ＲＳＤ（ｎ＝６）分别是３．６９％和１．４５％。     

沈阳市方形广场地下通道工程施工技术

通过地下通道施工实例,介绍了小导管超前注浆预加固的施工及注浆材料、注浆参数的确定方法。     

硅肥在黄河冲积土上的水稻肥效试验研究

试验研究结果表明：无论以炼铁水淬渣还是以赤泥为基料生产的硅肥,在河南省黄河冲积平原水稻上施用均获得１５％以上的增产效果,尤以赤泥的基本原料生产的硅肥增产效果最佳。     

新疆康古尔塔格金矿成矿反应体系及动力学分析

对康古尔塔格剪切带型金矿成矿体系地质地球化学特征研究后认为：①康古尔塔格金矿形成于脆韧性剪切变形和脆性变形阶段;②热液成矿反应体系包括成矿反应、控制反应及缓冲控制反应３类;③容矿构造活动方式有脆韧性缓冲转换作用、脆性破裂作用两种,前者构造环境有利于形成蚀变岩型矿化,后者则有利于形成石英脉状矿化;④成矿反应热力学性质和反应进行的程度——矿石品位受所处的地质环境和构造动力学条件的制约。     

石墨炉原子吸收法测定铝矾土中的硅

通过对照硅在热解石墨管、涂钼及涂钨石墨管中的原子化行为，选用涂钼石墨管和Ｌａ做基体改进剂，石墨炉原子吸收法测定铝矾土中的硅。经铝矾土管理样分析验证，方法可靠。实际样品分析结果与重量法和钼蓝法相符，对质量分数ｗ（ＳｉＯ２）在４％水平的铝矾土进行分析（ｎ＝５），其ＲＳＤ在１２％～１７％。     

Reach-Scale Cation Exchange Controls on Major Ion Chemistry of an Antarctic Glacial Meltwater Stream

McMurdo dry valleys of Antarctica represent the largest of the ice-free areas on the Antarctic continent, containing glaciers, meltwater streams, and closed basin lakes. Previous geochemical studies of dry valley streams and lakes have addressed chemical weathering reactions of hyporheic substrate and geochemical evolution of dry valley surface waters. We examine cation transport and exchange reactions during a stream tracer experiment in a dry valley glacial meltwater stream. The injection solution was composed of dissolved Li⁺, Na⁺, K⁺, and Cl^-. Chloride behaved conservatively in this stream, but Li⁺, Na⁺, and K⁺ were reactive to varying degrees. Mass balance analysis indicates that relative to Cl^-, Li⁺ and K⁺ were taken up in downstream transport and Na⁺ was released. Simulations of conservative and reactive (first-order uptake or generation) solute transport were made with the OTIS (one-dimensional solute transport with inflow and storage) model. Among the four experimental reaches of Green Creek, solute transport simulations reveal that Li⁺ was removed from stream water in all four reaches, K⁺ was released in two reaches, taken up in one reach, and Na⁺ was released in all four reaches. Hyporheic sediments appear to be variable with uptake of Li⁺ in two reaches, uptake of K⁺ in one reach, release of K⁺ in two reaches, and uptake of Na⁺ in one reach. Mass balances of the conservative and reactive simulations show that from 1.05 to 2.19 moles of Li⁺ was adsorbed per reach, but less than 0.3 moles of K⁺ and less than 0.9 moles of Na⁺ were released per reach. This suggests that either (1) exchange of another ion which was not analyzed in this experiment or (2) that both ion exchange and sorption control inorganic solute transport. The elevated cation concentrations introduced during the experiment are typical of initial flows in each flow season, which flush accumulated dry salts from the streambed. We propose that the bed sediments (which compose the hyporheic zone) modulate the flushing of these salts during initial flows each season, due to ion exchange and sorption reactions.     

盐渍土冬小麦施用硅肥效应的试验研究

通过对盐渍土施用硅肥后土壤及作物中氮、磷、钾、硅等营养元素的分析，发现施硅肥后土壤中的碱解氮、速效磷、速效钾和有效硅含量都有明显提高，小麦茎杆和籽粒中的氮、磷、钾、硅的含量也比对照处理的含量高，小麦抗逆性、光合作用等都有明显改进，增产幅度达22．7％；最后简要说明了硅肥对盐渍土的改良作用。     

湖北清江榨洞石笋中可溶硅的测定及其古气候意义研究

洞穴石笋蕴含着丰富的古气候信息，其正确解译有赖于各类古气候替代指标的开发，应用改进的硅钼兰分光光度法测定湖北清江榨洞石笋中痕量可溶硅，探讨其古气候指示意义。结果表明，石笋中可溶硅含量记录了岩溶地下水的硅酸组成，后进反映了气候控制下土壤的化学风化作用。因而，石笋可溶硅是一个潜在的古气候（特别是古湿度）替代指标。     

硅肥在杂交水稻上的肥效研究

水稻是喜硅作物，许多国家把硅称为水稻的第四大营养元素，通过在北亚热带地区河南省信阳地区潴育性水稻土上试验表明，在杂交水稻上施用硅肥，不仅可改善水稻的株高，有效穗数，穗粒数，实粒数，千粒重等生物学性状，而且施用硅肥还可增强杂交水稻抗旱，抗病虫害能力，从而提高稻谷产量19．8％－24．7％，同时，硅肥的施用能够使杂交水稻提早成熟，试验结果表明，在杂交水稻上，硅肥与氮磷肥配合施用比单独施用硅肥的增产效果和经济效益好，少量分次施用比一次性底施效果好。