成岩作用中的地下水碳酸体系与方解石溶解度

方解石在沉积岩成岩环境中的溶解度与地下水化学特征、温度等有着极为密切的关系。地下水碳酸体系中各碳酸组分的比例是溶液pH值的函数,可溶性CO2、HCO3-和CO32-分别在pH≤pK1的酸性介质、pK1≤pH≤pK2的弱酸至中性介质和pH≥pK2的碱性介质中具有绝对数量。而地下水体系中碳酸总量及各组分的变化受到pH值、气相CO2分压PCO2及固相方解石的溶解-沉淀效应的控制。通过限定溶液中离子的电价平衡和质量守恒约束条件可以确定各种温压环境中的地下水组成及方解石的溶解度特征。溶液pH值和温度是方解石溶解度的最直接的控制因素,且方解石的溶解随pH值不同分别在强酸、弱酸和碱性介质中表现出不同的反应方式。基于质量守恒条件,溶液中初始[ΣCO2]-[Ca2+]值对中性至碱性介质中的方解石溶解度带来很大的影响,当[ΣCO2]0<[ca2+]0有利于方解石的溶解,当[σco2]0>[Ca2+]0时有利于方解石的沉淀。如果CO2—H2O—CaCO3体系同时受到电价平衡和质量守恒条件的约束,则方解石只在酸性介质中溶解,碱性介质中沉淀。新疆塔里木盆地库车坳陷克拉2气田及相关储层中方解石分布特征表明,该区碎屑岩储层中方解石的大量沉淀发生于重碳酸钠型地下水环境中,而孔隙度极好、次生孔隙发育的储集段则出现于氯化型的地下水环境,从而验证了成岩作用中地下水类型对方解石溶解—沉淀的控制机制。      

雅砻江锦屏水电工程区岩溶水化学特征探讨

探讨了雅砻江锦屏水电工程区岩溶水中的宏量元素、微量元素和碳氧同位素的特征。得出如下结论: ( 1)左岸的砂板岩裂隙水,水类型为SO4- HCO3 - Mg型;右岸的大理岩岩溶- 裂隙水,水类型为HCO3 - Ca 型及HCO3 - Mg- Ca 型。( 2)岩溶水形成受两种形成机制控制,即碳酸作用型和硫酸作用型。      

西南岩溶环境中典型植物适应机制的初步研究

岩溶生态系统是受岩溶环境制约的生态系统,中国西南7省1市岩溶环境中存在石漠化趋势。植被的恢复和生态重建具有非常重要的意义。土壤微生物和植物的碳酸酐酶(carbonic anhydrase,简称CA)在生物岩溶作用中扮演重要角色,对岩溶生态系统的良性演化具有重要作用。从元素迁移的生物地球化学特性和植物、微生物的碳酸酐酶等生理生化指标出发,考察西南岩溶环境中典型植物可能的适应机制,即植物适应偏碱性逆境、高钙逆境、土壤贫瘠逆境、干旱逆境的机制。根据典型植物在西南岩溶环境中的适应机制和植被演替规律,从改善立地条件入手,先草后灌木、乔木来进行石漠化治理。与非岩溶区植物相比,西南岩溶区植物的铝含量较低,重金属(如铅、汞)的含量较低,是一种较优良的绿色植物。由于岩溶区土壤含水量较低等原因导致植物脯氨酸含量的显著增加,脯氨酸具有抗氧化活性,螯合金属离子减少其毒性等特性,可以开发富含脯氨酸的特种食品。这表明在岩溶环境中经济植物的地域性开发意义重大。     

乙酸和碳酸对粘土土工性状影响的试验

对加入不同浓度乙酸和碳酸的土样做室内土工试验,并进行机理分析。试验结果表明:乙酸根、碳酸根通过改变粘土颗粒双电层的厚度、极性水分子的吸附量,使土的结构发生凝聚或分散,引起压实粘土的塑性、渗透性等变化。其中,乙酸根是通过溶解粘土矿物中的铝,提高了粘土的渗透系数和塑性指数;而碳酸根是以其与金属离子发生化学反应生成难溶性碳酸盐的方式,降低了粘土的渗透系数。这为判断垃圾堆放场粘土衬垫工程的稳定性提供了依据。     

乌江流域上游段土地利用类型对水体碳酸酐酶活性的影响及其生态意义

在乌江流域上游段选取来自不同土地利用类型的34个地表水采样点和27个地下水采样点,比较研究不同土地利用类型对地表水及地下水水体碳酸酐酶（CA）活性的影响。结果表明,在乌江流域上游段来自不同土地利用类型的所有采样点的地表水及地下水中均能检测出CA活性。比较来自不同土地利用类型的地下水及地表水平均CA活性,总体而言,平均CA活性从高到低均依次为：乔木林地、灌木林地、灌草丛地、农业用地和居民区,而且,来自乔木林地、灌木林地和灌草丛地的地下水平均水体CA活性显著高于地表水。相关性分析结果表明,地表水和地下水中水体CA活性与HCO3-浓度均呈正相关。本研究结果表明水体CA对流域岩溶碳汇潜力的贡献值得进行广泛而深入的研究。     

Carbon isotopic fractionation in macroalgae from Cádiz Bay (Southern Spain): Comparison with other bio-geographic regions

The ¹³C signature of forty-five macroalgal species from intertidal zones at Cádiz Bay was analysed in order to research the extension of diffusive vs. non-diffusive utilisation of dissolved inorganic carbon (DIC) and to perform a comparison with data published for other bio-geographic regions. The ∂¹³C values ranged from −6.8‰ to −33‰, although the span of variation was different depending on the taxa. Thus, ∂¹³C for Chlorophyta varied from −7‰ (Codium adhaerens) to −29.6‰ (Flabellia petiolata), while all the Phaeophyceae (excepting Padina pavonica with ∂¹³C higher than −10‰) had values between −10‰, and −20‰. The widest variation range was recorded in Rhodophyta, from values above −10‰ (Liagora viscida) to values lower than −30‰ obtained in three species belonging to the subclass Rhodymeniophycidae. Accordingly, the mean ∂¹³C value calculated for red algae (−20.2‰) was significantly lower than that for brown (−15.9‰) and green algae (−15.6‰). Most of the analysed red algae were species inhabiting crevices and the low intertidal fringe which explains that, on average, the shaded-habitat species had a ∂¹³C value lower than those growing fully exposed to sun (i.e. in rockpools or at the upper intertidal zone). The comparison between the capacity for non-diffusive use of DIC (i.e. active or facilitated transport of HCO₃⁻ and/or CO₂) and the ∂¹³C values reveals that values more negative than −30‰ indicate that photosynthesis is dependent on CO₂ diffusive entry, whereas values above this threshold would not indicate necessary the operation of a non-diffusive DIC transport mechanism. Furthermore, external carbonic anhydrase activity (_extCA) and ∂¹³C values were negatively correlated indicating that the higher the dependence of the photosynthesis on the CO₂ supplied from HCO₃⁻ via _extCA, the lower the ∂¹³C in the algal material. The comparison between the ∂¹³C values obtained for the analysed species and those published for species inhabiting other bio-geographic areas (warm-temperate, cold and polar) suggests that globally (at least for the red and brown algae) the non-diffusive entry of DIC is more widely spread among the species from Cádiz Bay than among those of polar regions. If it is assumed that non-diffusive use of DIC implies saturation of photosynthesis at the present-day CO₂ concentration in seawater, our data indicate that the potential impact of the acidification on photosynthesis in the seaweed communities will be different depending on the latitude.     

温度对水中碳酸平衡的影响浅析

本文通过理论分析和计算探讨了0～100℃范围内不同温度下的碳酸平衡问题,分析了H2CO3*、HCO3-和CO32-三种碳酸在不同温度和pH条件下的水中所占比例及分布规律。认为0～100℃范围内pH0在8.60～8.22之间变化,变化范围较小;三种碳酸在不同温度下随pH变化过程中所占比例存在差异,但差异也不大;在0～100℃范围内不管温度高低,均表现出酸性水中H2CO3*占优势,碱性水中CO32-占优势,偏酸、偏碱及中性水中HCO3-占优势;在较低pH下由于水中CO32-含量很少,因此用常规方法一般是难以检测到的。      

Stable Isotope Ratios and the Evolution of Acidulous Ground Water

Ground waters in North Hesse (Germany) are conspicuous by high amounts of dissolved inorganic carbon (DIC) at low pH. The DIC is received from the uptake of soil CO₂ and CO₂ of volcanic origin and the subsequent dissolution ofTriassic and Permian limestone and dolomites. The volcanic CO₂ is related to Miocene basaltic magma which has liberated gaseous CO₂ during thebreakthrough to Triassic and Permian sediments. The volcanic CO₂ (-6 < ¹³CCO₂ < -3, PDB) was trapped within pore spacesand intra- and intergranulares of Permian evaporites and Triassic sandstones and was stored within such reservoirs until recent times. The uptake of volcanic CO₂ occurs as ground water migrates through such reservoirs. The ¹³ C/¹² C-signatures of the DIC indicate mixture of soil-CO₂and CO₂ of volcanic origin for the dissolution of marine limestone and dolomites. The obtained two types for CO₂ of volcanic origin with ¹³C_{CO 2}-values of -10 ± 3 and +2 ± 2 can be explained by diffusion of CO₂ through micropores, faults, and interfacesof solids. This mobilisation of CO₂ is accompanied with a kinetic fractionation of -9. ¹³ C-depleted CO₂ is liberated from the reservoir,whereas ¹³ CO₂ is accumulated in the residue     

喀斯特地区碳酸酐酶与环境的关系及意义

本文综述了喀斯特地区碳酸酐酶及其与环境的关系和地球化学意义。碳循环通过碳酸酐酶影响水生生态系统。碳酸酐酶是水体碳循环的一个重要因子，是生物地球化学作用的一个重要标志。不同环境条件如水、光、pH值、无机和有机离子等可对碳酸酐酶活性造成不同程度的影响。对于不同岩溶生态系统，植被覆盖率低的土壤碳酸酐酶活性低于植被种类丰富的土壤碳酸酐酶活性。同一类型岩溶生态系统不同岩溶地形的土壤碳酸酐酶活性也不同。研究岩溶地区土壤碳酸酐酶的地球化学作用，可以为岩溶生态系统碳循环的研究提供新的途径和方法，并为岩溶地区石漠化的防治提供理论依据。     

岩溶区和非岩溶区玉米光合作用与锌含量和碳酸酐酶关系的对比研究

采用田间试验方法对比研究岩溶区和非岩溶区玉米叶片光合作用与锌含量和碳酸酐酶活性的关系, 结果表明: 岩溶区施加有机肥的土壤有效锌和玉米叶片锌含量均高于非岩溶区,岩溶区和非岩溶区的玉米叶片的锌含量分别为47. 85mg /kg 和43. 35 mg /kg ;岩溶区玉米叶片的碳酸酐酶活性和光合作用也高于非岩溶区,岩溶区的碳酸酐酶活性平均为5. 622U,非岩溶区的碳酸酐酶活性平均为3. 485U;碳酸酐酶活性随玉米叶片的锌含量增加而提高,而玉米光合作用效率随碳酸酐酶活性增加而提高,反映了土壤锌含量对玉米叶片锌含量、碳酸酐酶活性和光合作用的控制。