成都市冬季不同粒径大气颗粒物水溶性无机离子的变化特征

利用Anderson冲击式分级采样器,在2010年冬季采集了成都市城东区不同粒径的大气颗粒物样品,分析了9种水溶性离子(SO42-、NO3-、Cl-、F-、NH4+、Ca2+、Mg2+、K+、Na+)的含量,并探讨其分布变化特征.SO42-、NO3-、NH4+、Cl-、K+、Na+等离子主要集中在粒径为3.3～0.65μm的细颗粒物中,而Ca2+、Mg2+则集中在粒径为11 ～4.7μm的粗颗粒物中.SO42-、NO3-、NH4+、Ca2+是主要的无机离子;在不同天气条件下,5O42-、NO3-的质量浓度按雾天、阴天、雨天递减,且雾天较阴天高2.5倍左右,较雨天高5倍左右,而其他离子也高出2倍左右;在不同粒径颗粒物中[NO3-]/[SO42-]比值均较小(＜1),说明成都市目前仍然以固定(燃煤)污染源为主,移动污染源(汽车尾气)的影响正逐步增强.     

广州流溪河降水化学成分及其海洋源分析

通过2006年6月～2008年5月在广州流溪河地区采集的106次降雨水样(雨量范围0.7～268.6 mm)及其化学测试,论述了几类主要离子在降水中的含量特征、季节变化、物质的海洋来源以及雨水中离子平衡等.结果显示:(1)流溪河周边没有明显的点污染源,但酸雨降水量占总降水量的69.5%,说明降水中的污染物来自该地南部和北部污染区的中距离传输;如夏季和秋季时,台风等海洋气流把珠三角南部更多的NOx传输至该地,使得雨水中NO-3含量在夏季和秋季最大.(2)降水中的年平均F-、Cl-、NO-2、NO-3、PO3-4、SO2-4、NH+4、Ca2+、Mg2+、K+、Na+和Al3+离子浓度分别为3.76、22.80、0.45、25.22、0.86、62 9、41.5、35.77、2.93、5.45、14.8和0.943 μeq·L-1;且单个降水事件中的离子浓度大小与降水量呈负相关.(3)流溪河雨水酸度主要来自SO2-4、NO-3和Cl-1,且主要靠中和因子较大的NH+4、Ca2+、K+等阳离子起缓冲作用;该地降水沉降中的强酸酸量为2 053 keq hm-2 a-1,NH+4、Ca2+、K+、Mg2+、Al3+的缓冲量分别为0.865、0.745、0.114、0.061、0.020 keq hm-2 a-1.(4)降水化学的月和季节波动明显,酸雨主要集中于雨季,而旱季雨水酸度较低,这和重庆及北京的情况相反.(5)在雨水中化学成分Na+全部来源海洋的假设前提下,分析得出:绝大部分Mg2+和部分Cl-(80.07%)、SO2-4(2.91%)、Ca2+(1.86%)、K+(6.19%)来自于海洋,而F-、NO-3来自海洋的贡献率非常小,可以忽略不计.     

茂兰喀斯特地区森林降水分配的水化学特征

于2007年9月—2009年8月对中国西南茂兰喀斯特地区亚热带常绿落叶阔叶混交林大气降水、林冠穿透雨和树干茎流进行观测,分析了各降水分配中的养分离子(Ca2+、Mg2+、K+、Na+、NH4+、SO42-、NO3-、Cl-)浓度动态变化规律及年养分元素输入量。结果表明:7—9月,林外雨、林冠穿透雨和树干茎流中各养分离子浓度相对较低,12月—翌年2月,各降水分配中各养分离子浓度相对较高;降水通过林冠或树干后,除了Na+浓度无显著变化外,NH4+浓度表现下降趋势,Ca2+、Mg2+、K+、Cl-、NO3-和SO42-均表现增加趋势;林外雨的养分元素输入量顺序为Ca2+SO42--SNH4+-NCl-K+Na+Mg2+NO3--N。在林冠穿透雨+树干茎流中的养分元素输入量顺序为K+Ca2+Cl-SO42--SMg2+NH4+-NNO3--NNa+。与非喀斯特地区相比,林外雨中的各养分离子浓度较低,林冠穿透雨、树干茎流中的K+、Ca2+、Mg2+增加幅度较大。总体来看,独特的立地特征决定了该地区Ca2+、Mg2+的积极参与生态系统养分循环和K+高效循环的特征。     

模拟酸沉降对鼎湖山季风常绿阔叶林地表径流水化学特征的影响

通过模拟酸沉降实验,研究了旱季期间(10-3月份)鼎湖山季风常绿阔叶林在4种不同pH模拟酸雨处理(对照、pH 4.0、pH 3.5、pH 3.0)下地表径流水化学输出特征.结果显示:(1)地表径流pH随酸处理强度增强呈“U”型变化模式,酸沉降对地表径流pH的影响不显著(P＞0.05),表明模拟酸沉降尚未引起地表水的酸化.(2)地表径流中NO3-、SO24-浓度随酸处理强度增强略有增加;HCO3-浓度的变化模式与地表径流pH类似.酸根离子浓度与地表径流pH相关性分析表明,SO24-、HCO3-有助于提高地表水抗酸化能力而NO3-则有助于促进地表水酸化.(3)地表径流中盐基离子对酸沉降的响应不尽相同.pH 3.0处理显著提高地表径流中Ca2+、Na+浓度;Mg2+浓度具有随酸处理梯度增强而增加的趋势;K+受模拟酸度的影响小.表明强酸(pH3.0)处理将导致土壤Na+、Ca2+、Mg2+盐基离子流失.(4)酸沉降具有诱发土壤可溶性有机碳(DOC)流失的倾向,增加地表水受有机污染的风险.     

电子受体和光照对土壤CH4排放相关微生物功能基因丰度的影响

为探究光照条件下添加不同电子受体对土壤甲烷排放的影响及微生物的响应,本研究在土壤中添加3种电子受体(Fe3+、NO3-、SO42-)共设计8个处理,即黑暗+ Fe3+(DF)、黑暗+NO3-(DN)、黑暗+SO42-(DS)、黑暗+蒸馏水(DCK)、光照+Fe3+(LF)、光照+NO3-(LN)、光照+SO42-(LS...     

模拟酸雨胁迫下钙对龙眼光合功能的调节作用

以福建省主栽品种乌龙岭龙眼为材料研究了模拟酸雨胁迫下钙对龙眼光合功能的调节作用 .结果表明 ,叶绿体的反应介质中Ca2 + 浓度在 0～ 5mmol·L-1范围内可增加其光还原活性 ,以 3 .5mmol·L-1的活性最高 ,比对照增加 41.90 % ;而 2mmol·L-1EGTA会使其活性下降 2 6 .0 6 % ;Mn2 + 和Mg2 + 对光还原活性均有抑制作用 .0～ 6mmol·L-1的Ca2 + 可提高叶绿体的光合磷酸化活性 ,最适的浓度为 4.5mmol·L-1;0～ 8mmol·L-1的Ca2 + 可提高叶绿体超氧物歧化酶 (SOD)活性 ,最适浓度为 6mmol·L-1.pH 3 .0的酸雨胁迫下 ,10mmol·L-1和 15mmol·L-1Ca(NO3) 2 均可减缓叶绿素的降解 ,稳定叶圆片的膜结构 ,降低膜透性 ,以 15mmol·L-1的效果较佳 ;Ca(NO3) 2 浓度超过 2 0mmol·L-1加剧了酸雨对叶片的伤害作用 .喷15mmol·L-1Ca(NO3) 2 可增加叶片光合速率 ,表现出模拟酸雨胁迫下钙对龙眼叶片的良好保护作用 .     

黄土区降水降尘输入农田土壤中的氮素评估

随着人类活动引起大气活性氮的急剧增加,大气氮沉降亦明显增加,由此引发的各生态系统的响应也逐渐表现出来.研究黄土区氮沉降,对农业生态系统的氮素循环与平衡提供一定的数据支持,同时为农民科学合理施肥提供依据,为研究氮沉降的环境生态效应和生物有效性提供科学支撑.用APS-2A型降水降尘自动采样器对陕西杨凌和洛川地区2006～2007年的降水降尘输入氮总量、月动态变化及各形态N的贡献率进行了监测与分析.结果显示杨凌点2006年总降雨量为507.8 mm,总N沉降通量为20.6 kg/(hm2·a),其中N湿沉降通量为19.1 kg/(hm2·a),占93%;降尘输入的N通量为1.5 kg/(hm2·a),占7%.总N沉降通量中NO-3-N为7.3 kg/(hm2·a),占36%.洛川点2006年6月～2007年5月总降雨量为579.5 mm,总N沉降通量为12.7 kg/(hm2·a),其中N湿沉降通量为11.4 kg/(hm2·a),占90%;降尘输入N的通量为1.2 kg/(hm2·a),占10% .总N沉降通量中NO-3-N为8.7kg/(hm2·a),占69%.两个点N沉降通量和氮素形态的差异在很大程度上反映了活性N主要来自人为活动,即农业生产排放的活性N.     

模拟酸雨对杉木幼苗-土壤复合体系土壤呼吸的短期效应

为了解酸雨对土壤碳释放的作用,选取对酸沉降敏感的杉木(Cunninghamia lanceolata)幼苗-土壤复合系统,分成重度酸雨(pH值2.5)、中度酸雨(pH值4.0)和对照(pH值5.6)3个处理区组,进行了2a模拟酸雨胁迫盆栽实验。通过分析酸雨短期作用下土壤酸化的状况以及土壤呼吸的变动,发现:(1)对照组土壤pH值虽有下降,但土壤缓冲体系无显著变化。重度酸雨组土壤pH值持续下降至3.71,土壤残留交换性Ca2+和Mg2+含量明显降低,土壤缓冲体系转成铝缓冲体系,土壤明显酸化。中度酸雨组土壤pH值略低于对照,土壤残留交换性Ca2+含量维持在40.15-42.76μg·g-1(烘干土),而交换性Mg2+含量下降,土壤缓冲体系无显著变化。(2)非模拟酸雨胁迫状况下(对照组),2007年和2008年年均土壤呼吸速率分别为1.41μmol·m-2·s-1和1.42μmol·m-2·s-1,土壤呼吸作用稳定。模拟酸雨短期内以抑制土壤呼吸为主。重度酸雨使土壤呼吸作用持续减弱,2007年和2008年年均土壤呼吸速率分别下降了14%和28%;中度酸雨虽未造成土壤的显著酸化,但该处理组年均土壤呼吸速率2007年增加了8%,2008年则降低了15%。模拟酸雨对土壤呼吸的影响随着酸雨的持续而加强。     

广州市酸雨成分及其相关分析

分析了2003年11月-2004年10月广州市龙洞79次降雨的化学组分及其各组分之间的相关关系。得出:(1)观测期间总降雨量1359.8,单次降雨的pH值在3.22-7.29之间,平均4.83;以pH<5.6为酸雨的临界值,则酸雨频率占降雨次数的77.2%或占降雨量的81.5%;(2)广州降水的化学组成以SO₄^2-、Cl^-和NO₃^-为主要阴离子,阳离子中以Ca²⁺、NH₄⁺、Na⁺所占比例较大;(3)广州地区酸雨属硫酸型,降雨中的SO₄^2-、NO₃^-、PO₄^3-、Cl^-、NH₄⁺、K⁺、Na⁺、Ca²⁺、Mg²⁺离子浓度分别为0.150,0.045,0.002,0.163,0.058,0.006,0.013,0.083和0.007mol·L^-1,单次降雨的SO₄^2-/NO₃^-比值在0.42-17.6之间,年平均为3.33,该值比西南地区相应值低许多,而且与同一地点5年前测定的结果相比较,SO₄^2-/NO₃^-比值有变小的趋势,说明广州地区NO_x排放量高逐渐增加;(4)广州地区酸雨有着明显的季节变化规律,春、夏、秋季酸雨比较严重,冬季酸雨较少出现,这与西南地区的重庆(冬季酸雨较春季严重)酸雨季节规律相反;(5)通过SPSS统计分析得出,雨量与各化学组分含量成负相关,说明雨量对大气污染物质的稀释作用;酸雨各化学成分之间存在着一定的相关性,如SO₄^2-与Ca²⁺,NO₃^-与NH₄⁺,K⁺与Na⁺、Mg²⁺离子,Na⁺与Mg²⁺等都存在显著的正相关,利用这种相关可以建立某些酸雨成分的预测模型。     

木麻黄幼苗对模拟酸雨胁迫的响应和Ca2+的调节作用

随着酸雨pH值的下降,木麻黄幼苗中超氧化物歧化酶(SOD)活性、叶绿素含量和叶绿素a/b值逐渐下降,过氧化物酶(POD)活性、可溶性蛋白质含量、丙二醛(MDA)含量和超氧阴离子自由基(O2-·)含量逐渐增加,过氧化氢酶(CAT)活性和脯氨酸含量先升后降.在同一强度酸雨胁迫下,经0.1和1 mmol·L-1Ca(NO3)2处理的SOD活性、CAT活性、叶绿素含量和叶绿素a/b值相对较高,POD活性、蛋白质含量、MDA含量、O2-·含量和脯氨酸含量相对较低,Ca2 可缓解酸雨对木麻黄幼苗的伤害.     

广州市森林土壤水化学和元素收支平衡研究

为了探讨酸沉降对森林生态系统的影响,于1998年4月至1999年3月对广州市3个不同林分试验点的降雨,林内穿透雨和土壤渗透水进行了物理量测定和化学分析,据此计划了元素的收支平衡,研究表明：（1）SO4^2-和Ca^2 是土壤水中最主要的阴,阳离子,土壤水中的主要组分浓度的变化与树冠和凋落物淋溶的贡献以及土壤中一系列物理化学过程（如硝化作用,吸附作用,阳离子交换反应）有关;（2）土壤水中H^ 和Al^3 浓度的增高是土壤酸化的重要指标,可能对森林植被构成潜在危害;（3）S－沉降（＞110kg/hm^2.a)可能不是目前土壤酸化的主要原因,也没引起土壤中碱性离子的大量淋失,由于研究区土壤有较强的吸附So4^2-的能力和容量,So4^2-和与之关系密切的Ca,Mg,K等元素在土壤中处于积累阶段;（4）过量的N沉降（＞20kg/hm^2.a)和NH4^ 的硝化 作用是广州市森林土壤进一步酸化的主要原因,由于该地区NOx排放量逐年上升,因此N沉降对森林生态系统的负面影响会进一步加剧。     

北京西山不同人工林枯落物层的水化学性质

通过采集降雨经枯落物后的水样,初步研究了北京西山地区油松林和栓皮栎林林下枯落物层的水化学性质.结果表明:大气降水经过林冠进入枯落物层后,油松林和栓皮栎林林下不同元素的浓度发生明显变化.枯落物水中K 、Na 、Ca2 、Mg2 、NH4 -N和NO3--N的浓度随时间的变化趋势基本一致.穿透雨经过枯落物层后,水中K 、Na 、Ca2 和Mg2 的平均浓度增加,而NH4 -N、NO3--N的平均浓度减小.其中,栓皮栎林和油松林中Ca2 浓度分别增加了7.54和5.27mg.L-1.栓皮栎林下枯落物层中K 、Na 、Ca2 、Mg2 的平均浓度高于油松林,而NH4 -N、NO3--N的平均浓度则低于油松林;经降水淋溶作用后,栓皮栎林和油松林林下枯落物归还林地的养分分别为41.59和58.12kg.hm-2,其中归还林地较多的是Ca2 ,其次是K .     

诺卡氏菌形放线菌β-甘露聚糖酶的纯化和性质

产β－１,４－Ｄ甘露聚糖酶的诺卡氏菌形放线菌（Ｎｏｃａｒｄｉｏｆｏｒｍ ａｃｔｉｎｏｍｙｃｅｔｅｓ）菌株ＮＡ３－５４０,发酵培养７２ｈ,发酵液离心去菌体,上清经硫酸铵沉淀,９５％乙醇沉淀,ＣＭ－Ｓｅｐｈａｄｅｘ Ａ５０柱层析、羟基磷灰石柱层析、ＤＥＡＥ－纤维素离子交换及Ｓｅｐｈａｄｅｘ Ｇ－１００分子凝胶过滤柱等步骤,β－甘露聚糖酶的比活提高了１３７倍,获得凝胶电泳均一的蛋白样品。经ＳＤＳ－ＰＡＧ     

The effect of stand age on throughfall chemistry in spruce stands in the Potok Dupniañski catchment in the Silesian Beskid Mountains, southern Poland

The chemical composition of throughfall depends on the age of the Norway spruce (Picea abies Karst) stands and season of the year. The pH of throughfall decreased and the amount of hydrogen ion in throughfall deposited to the soil increased with increasing age of spruce stands, especially in the winter season. Concentrations of K+, H+, SO4(2-), Mn2+, and NH4(+) in throughfall were higher than bulk precipitation for the whole year and K+, H+, and Mn2+ concentrations were higher in throughfall in winter and the growing season. This indicates that these ions were washed out or washed from the surface of needles and/or the bark, and that NO3(-), NH4(+), Ca2+, Mg2+, Fe2+, and Zn2+ were absorbed in the canopy. The effect of high nitrogen deposition, above critical loads, and an increase in the amount of sulfur and in the sum of the strong acids (S-SO4(2-) and N-NO3(-)) that reached the soil with throughfall may have implications for the vitality of spruce stands, especially in older age classes. The application of Principal Component Analysis (PCA) has led to identification of five factors responsible for the data structure ("mineral dust", "acidic emissions", "heavy metals-dust particles", "ammonium [NH4(+)]", and "H+"). They explain more than 60% of the total variance system. The strong positive correlation between stand age class and ionic concentrations in throughfall occurs for all year and the winter period for ions within the following categories: "acidic emissions", SO4(2-) + NO3(-); "heavy metals-dust particles", Fe2+ + Mn2+ + Zn2+; "mineral dust", Na+ + K+ + Ca2+ + Mg2+; "NH4(+)"; and "H+". The strength of the relationship decreases in the growing period, probably due to processes occurring in the canopy (adsorption, leaching, etc.).     

Method for determination of sodium, potassium, calcium, magnesium, chloride, and phosphate in the rat choroid plexus by flame atomic absorption and visible spectroscopy

A rapid simple technique for the measurement of Na+, K+, Mg2+, Ca2+, PO4(3-), and Cl- was developed to analyze ion contents in the choroid plexus of the rat. The technique involves digestion in piperidine, precipitation of proteins with HClO4, and analysis of Na+, K+, Ca2+, and Mg2+ by atomic absorption spectroscopy and Cl- and PO4(3-) by visible spectroscopy. The coefficient of variation for the measurement of eight replicates was 1-3% for all ions. Analysis of choroid plexuses from eight rats yielded coefficients of variation of about 6% and the values for Na+, K+, and Cl- compared favorably to previous works. The analytical procedure described in this paper allows the determination of six major physiologic ions in rat choroid plexus (4 mg wet wt).     

Gill (Na+ + K+)- and Na+-stimulated Mg2+-dependent ATPase activities in the gilthead bream (Sparus auratus L.)

1. Gilthead gill 10(-3) M ouabain-inhibited (Na+ + K+)-ATPase and 10(-2) M ouabain-insensitive Na+-ATPase require the optimal conditions of pH 7.0, 160 mM Na+, 20 mM K+, 5 mM MgATP and pH 4.8-5.2, 75 mM Na+, 2.5 mM Mg2+, 1.0 mM ATP, respectively. 2. The main distinctive features between the two activities are confirmed to be optimal pH, the ouabain-sensitivity and the monovalent cation requirement, Na+ plus another cationic species (K+, Rb+, Cs+, NH4+) in the (Na+ + K+)-ATPase and only one species (Na+, K+, Li+, Rb+, Cs+, NH4+ or choline+) in the Na+-ATPase. 3. The aspecific Na+-ATPase activation by monovalent cations, as well as by nucleotide triphosphates, opposed to the (Na+ + K+)-ATPase specificity for ATP and Na+, relates gilthead gill ATPases to lower organism ATPases and differentiates them from mammalian ones. 4. The discrimination between the two activities by the sensitivity to ethacrynic acid, vanadate, furosemide and Ca2+ only partially agrees with the literature. 5. Present findings are viewed on the basis of the ATPase's presumptive physiological role(s) and mutual relationship.     

Isolation and biochemical characterization of delta-aminolevulinic acid dehydratase from Streptomyces yokosukanensis ATCC 25520

In this study, delta-aminolevulinic acid dehydratase from Streptomyces yokosukanensis ATCC 25520, producer of an unusual purine riboside antibiotic called nebularine, was purified and characterized. Purification procedures involved with ammonium sulphate precipitation and gel filtration techniques by use of Sephacryl S-200. After gel filtration a 90.76-fold purification was obtained. The maximum enzymic activity was observed in the supernatant after 100% precipitation. According to the data obtained from investigation, the enzyme was found to be a single polypeptide having molecular mass around 34.8 kDa. This was determined by SDS-PAGE. Its optimal temperature around 45 degrees C, and optimal pH was found to be 8.0. Some heavy metals, Pb2+, Zn2+, Fe3+, Co2+, Mn2+, Mg2+ inhibited its activity between 20-51%, Ni2+ increased its activity up to 15%.     

Functional association between K+-Cl- cotransporter-4 and H+,K+-ATPase in the apical canalicular membrane of gastric parietal cells

We studied whether K+-Cl(-) cotransporters (KCCs) are involved in gastric HCl secretion. We found that KCC4 is expressed in the gastric parietal cells more abundantly at the luminal region of the gland than at the basal region. KCC4 was found in the stimulation-associated vesicles (SAV) derived from the apical canalicular membrane but not in the intracellular tubulovesicles, whereas H+,K+-ATPase was expressed in both of them. In contrast, KCC1, KCC2, and KCC3 were not found in either SAV or tubulovesicles. KCC4 coimmunoprecipitated with H+,K+-ATPase in the lysate of SAV. Interestingly the MgATP-dependent uptake of (36)Cl(-) into the SAV was suppressed by either the H+,K+-ATPase inhibitor (SCH28080) or the KCC inhibitor ((R)-(+)-[(2-n-butyl-6,7-dichloro-2-cyclopentyl-2,3-dihydro-1-oxo-1H-inden-5-yl)oxy]acetic acid). The KCC inhibitor suppressed the H+ uptake into SAV and the H+,K+-ATPase activity of SAV, but the inhibitor had no effects on these activities in the freeze-dried leaky SAV. These results indicate that the K+-Cl(-) cotransport by KCC4 is tightly coupled with H+/K+ antiport by H+,K+-ATPase, resulting in HCl accumulation in SAV. In the tetracycline-regulated expression system of KCC4 in the HEK293 cells stably expressing gastric H+,K+-ATPase, KCC4 was coimmunoprecipitated with H+,K+-ATPase. The rate of recovery of intracellular pH in the KCC4-expressing cells after acid loading through an ammonium pulse was significantly faster than that in the KCC4-non-expressing cells. Our results suggest that KCC4 and H+,K+-ATPase are the main machineries for basal HCl secretion in the apical canalicular membrane of the resting parietal cell. They also may contribute in part to massive acid secretion in the stimulated state.     

The effects of monovalent cations Li+, Na+, K+, NH4+, Rb+ and Cs+ on the solid and solution structures of the nucleic acid components. Metal ion binding and sugar conformation.

The interactions of the monovalent ions Li+, Na+, K+, NH4+, Rb+ and Cs+ with adenosine-5'-monophosphoric acid (H2-AMP), guanosine-5'-monophosphoric acid (H2-GMP) and deoxyguanosine-5'-monophosphoric acid (H2-dGMP) were investigated in aqueous solution at physiological pH. The crystalline salts M2-nucleotide.nH2O, where M = Li+, Na+, K+ NH4+, Rb+ and Cs+, nucleotide = AMP, GMP and dGMP anions and n = 2-4 were isolated and characterized by Fourier Transform infrared (FTIR) and 1H-NMR spectroscopy. Spectroscopic evidence showed that these ions are in the form of M(H2O)n+ with no direct metal-nucleotide interaction, in aqueous solution. In the solid state, Li+ ions bind to the base N-7 site and the phosphate group (inner-sphere), while the NH4+ cations are in the vicinity of the N-7 position and the phosphate group, through hydrogen bonding systems. The Na-nucleotides and K-nucleotides are structurally similar. The Na+ ions bind to the phosphate group of the AMP through metal hydration shell (outer-sphere), whereas in the Na2-GMP, the hydrated metal ions bind to the base N-7 or the ribose hydroxyl groups (inner-sphere). The Na2-dGMP contains hydrated metal-carbonyl and metal-phosphate bindings (inner-sphere). The Rb+ and Cs+ ions are directly bonded to the phosphate groups and indirectly to the base moieties (via H2O). The ribose moiety shows C2'-endo/anti conformation for the free AMP acid and its alkali metal ion salts. In the free GMP acid, the ribose ring exhibits C3'-endo/anti conformer, while a C2'-endo/anti sugar pucker was found in the Na2-GMP and K2-GMP salts and a C3'-endo/anti conformation for the Li+, NH4+, Rb+ and Cs+ salts. The deoxyribose has C3'-endo/anti conformation in the free dGMP acid and O4'-endo/anti in the Na2-dGMP, K2-dGMP and a C3'-endo/anti for the Li+, NH4+, Rb+ and Cs+ salts. An equilibrium mixture of the C2'-endo/anti and C3'-endo/anti sugar puckers was found for these metal-nucleotide salts in aqueous solution.