138 resultados para [Nle(4), D-Phe(7)]alpha-MSH
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对渔塘坝硒矿床中高硒的碳质硅质岩和碳质页岩样品进行了硒同位素测定. 测定结果显示, 其δ82/76SeNIST范围从-12.77‰ ~ 4.93‰, 总变化为17.7‰. 这是迄今所发现的自然界中最大的同位素分馏, 同时样品Ytb-5(高硒碳质页岩)的d 82/76SeNIST为-12.77‰, 也是目前所发现的自然界中最富硒轻同位素的样品. 根据硒同位素的分布特征, 结合其他地质证据和地球化学指标, 认为“氧化-还原模式”是对矿床中自然硒大量出现的合理解释. 同时, 硒同位素在自然界中较大的分馏效应也证明其作为一种新的地球化学示踪剂有其独特的应用潜力.
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喀斯特石漠化是我国喀斯特地区所面临的严峻生态问题,目前对石漠化发生机制的研究主要集中在宏观调查与状态的描述,因此所提出的是总体的生态恢复治理模式。但石漠化的发生发展在喀斯特地区存在着显著的内部差异性,需缩小石漠化研究的空间范围,考虑石漠化发生的不同背景,发现差异存在的规律性,才能有针对性地找到石漠化治理的普遍适用的模式。 本文以遥感与地理信息系统相结合的研究手段,从全省到小流域的不同研究尺度下,以景观生态学的研究方法为思路,深入分析了不同自然条件下石漠化景观的生态分异规律,并以此提出喀斯特地区小流域生态治理的不同对策。 在研究中取得了以下几点认识: (1)贵州省景观在空间上存在地域分异,整体景观退化,其中西部和西南部地区的退化更严重,黔东区和黔北区生态环境最好;类型上以林地退化差异较大、草地退化较一致。全省景观在时间上体现出波动特征,类型间转换关系复杂,景观具有不稳定性;生态系统服务功能价值总体下降,生态退化在局部地区加重。 (2)连续性碳酸盐岩地区一致性表现为以灌木林地为优势景观、林地和草地以次生景观为主,景观中大多数为偏小斑块,斑块形状趋于规则,人为干扰大的景观中斑块的破碎化更加明显。与连续性白云岩相比,连续性石灰岩地区空间异质性强、分割破碎、稳定性差、水资源利用率低下、抗干扰能力弱 ,退化更严重、更易发生逆向演替。 (3)连续性碳酸盐岩地区中灌木林地也是最不稳定的类型,并同时存在正向和逆向的双向演替。此外,连续性白云岩地区的中覆盖度荒草地、连续性石灰岩地区的疏林地为易受干扰景观。连续性石灰岩地区的景观变化率高于连续性白云岩地区,变化幅度较大,变化类型集中。 (4)连续性白云岩小流域中石漠化形成的人为作用明显,带有低坡度特征。斜坡区石漠化景观发生频率高且强度大,处于不稳定状态;峡谷区石漠化面积虽大但不严重;高原区景观稳定,生态环境最优。连续性石灰岩小流域的生态环境对地貌区带变化敏感,随着高原区到峡谷区的过渡,石漠化发生愈频繁兼强度加大,但主要驱动力的人为因素逐渐减少、自然营力作用逐步加强。 (5)通过研究区域间在相同岩性和地貌条件下的坡向和石漠化的对比,可以认为坡向对石漠化的发生并无直接影响。 (6)在高程因子的作用下,连续性碳酸盐岩地区的石漠化发生既有差异性又有着一定的相似性。连续性白云岩的峡谷区中随着高程的增加,石漠化发生面积愈大。连续性石灰岩小流域的较高海拔上高原区和峡谷区的强度石漠化较易发生,且石漠化现象较普遍。其它的情况下,强度石漠化在偏低海拔上较易发生;在流域中部的海拔范围内石漠化的发生总体上以轻度、中度石漠化为主。 (7)在石漠化小流域恢复中提出了以空间地域分异为指导的分级治理原则。首先以岩性作为分级指标,连续性石灰岩优先于连续性白云岩地区。石灰岩地区中以高原区为生态恢复的首选,其次是峡谷区。白云岩的斜坡区是治理重点,高原区随后。
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本研究以西南喀斯特地区的王家寨小流域为研究对象,以植物叶片δ13C值为植物水分利用效率的指示值,结合利用氢氧同位素对植物的水分来源进行确认,通过研究小流域中不同土壤类型石漠化样地、不同季节、不同等级石漠化样地及喀斯特不同小生境中常见植物种水分利用效率及水分来源的差异,旨在从小生境、植物种、植物群落等不同尺度上探讨石漠化发生过程对植物长期水分利用的影响,了解不同水源的利用对植物水分利用效率的影响,了解喀斯特生态系统特有生境中植物对水分的竞争和利用策略,以加深对生态系统水分平衡的认识。通过研究,得出了以下几点认识:
1 喀斯特石漠化区植物叶片δ13C值的时空变化
(1)在本研究区,不同土壤类型区域植物群落δ13C值均随着石漠化的进行趋正,方差分析结果显示黄壤序列植物群落叶片δ13C值存在显著差异(F(3,80)0.01=2.72
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氮循环是水生生态系统中重要的营养循环,对它的研究能够为水环境评价以及解决日益严重的湖泊富营养化问题中的氮治理提供理论依据。水体中的有机质分为颗粒态有机质(POM)和溶解态有机质(DOM)两部分,它们在水体中与无机氮相互转化、相互作用,共同控制着整个水生生态系统内部的氮循环过程。稳定氮同位素技术作为有效的地球化学工具能够被用于追溯水生生态系统中的物质来源以及指示相关的生物地球化学循环作用。因此对有机质稳定氮同位素比值的测定有利用帮助我们了解它在水生生态系统中所扮演的角色,尤其是得到有机质参与的地球化学循环作用的直接证据,从而进一步完善对水生生态系统内部整个氮循环过程的研究。 本研究首先从根本上解决了限制溶解有机氮(dissolved organic nitrogen,DON)稳定氮同位素比值应用的测定技术上的难题。然后选择贵州高原湖泊―红枫湖和百花湖作为研究对象,测定了2003~2004年两湖水体中颗粒态有机氮同位素比值(δ15NPON)的季节及剖面变化,探讨了两湖季节性变化存在差异的原因以及红枫湖纵向水体剖面上δ15NPON的变化规律及影响因素。最后,在前人对红枫湖研究的基础上重点选择了2006~2007年间湖泊热分层不同时期具有代表性的几个月份进行了剖面采样。测定了不同月份纵向水体剖面上的DON、PON与NO3-三种氮形态的含量、δ15N值以及其它水化学参数,揭示了水体内部氮循环过程中的相关生物地球化学作用。同时,结合冬季湖泊枯水期外源输入河流以及湖泊水体横向剖面上的DON、PON与NO3-三种氮形态的含量及其δ15N值的变化,追溯了湖泊水体中各种氮形态的来源以及外源输入河流对湖泊水体的贡献。本研究得到以下几点结论: 1. δ15NPON值的季节性变化可以用于评价水生生态系统的营养状况,指示外源人为活动产生的工业废水和生活污水的影响。对2003~2004年间红枫湖和百花湖两湖表层湖泊水体中PON的δ15N季节性变化研究表明,红枫湖表层颗粒态有机质δ15NPON的变化范围为+3.7~+14.9‰;百花湖颗粒态有机质δ15NPON的变化范围为+1.3~+8.7‰。其季节性变化趋势不同。红枫湖表现为冬季(2月)和夏末秋初(9月)出现高值;冬季高值的出现主要受外源输入的工业废水中富含15N的无机氮源和有机颗粒的影响。百花湖在冬季(2月)出现最低值,夏末秋初(9月)出现高值;冬季最低值的出现则可能归功于生活污水中富含14N的有机颗粒的贡献。 2. 首次从整体角度得到了δ15NDON值变化区间的信息。红枫湖2006~2007年不同采样月份水体内部的δ15NDON测定结果显示,δ15NDON的变化范围为+1.0~+12.3‰,它与δ15NNO3-的变化范围:5.9~+22‰和δ15NPON变化范围:+2.8~+16.8‰接近。同时,研究还发现在浮游植物生长季节,表层水体不同形态氮的同位素比值普遍存在下述规律:δ15NNO3->δ15NPON>δ15NDON。原因是此时浮游植物是PON的主要组成部分,且吸收利用NO3-的过程是δ15NPON变化的主要控制因素,浮游植物通过分泌细胞外液等方式分解产生了的富含14N的DON,从而使得三种形态的氮同位素具有一定的继承关系。 3. 三种氮形态δ15N值的季节性变化趋势能够反映其来源的差异。纵向剖面水体中,2007年1月的δ15NNO3-最大,湖泊受外源河流携带的高δ15N及高含量NO3-的影响。2006年4月和2007年3月的δ15NNO3-较小,水体内部发生的强烈的硝化作用产生了大量富含14N的NO3-,是湖泊水体NO3-的重要内源。δ15NDON值表现为:除2007年3月表现异常外(出现异常高值),浮游植物生长季节(2006年4月和2006年7月)的 δ15NDON普遍小于其余月份,且纵向水体剖面上变化幅度均不太大,这与浮游植物生长季节DON主要来源于浮游植物分泌等作用产生的富含14N的组分有关。δ15NPON值表现为冬季(2007年1月)具有最高值,受外源输入河流中富含15N的有机颗粒的影响。 4. PON降解方式的不同可能引起生成的δ15NDON存在差异。PON在有氧条件下发生硝化降解时,由于富含14N的组分优先被释放,因此生成的DON组分的δ15N值较小,如2006年4月10m以上水体和2006年7月10m以上水体;而当PON在厌氧条件下发生反硝化降解时,富含15N的组分则优先被释放,从而使得生成的DON其δ15N较大,如2006年4月18m以下水体和2006年7月10m以下水体。 5. 纵向水体剖面上δ15NPON的显著变化来源于其组成的变化,并且不论是硝化细菌还是反硝化细菌,当它们作为PON的主要组分时均会造成δ15NPON的减小,如2006年7月和2007年3月中下部水体。 6. 三种氮形态同位素比值的结合能够更加有效地示踪有机质来源的变化。如2007年1月纵向水体剖面,整个水体剖面氮含量无明显变化,而氮同位素比值则有显著变化。20m处δ15NPON、δ15NNO3-和δ15NDON均在此发生转折,显示20m可能是外源输入与内部水体的分界层。此时,横向水体剖面上,采样点4处NO3-显著增加,而δ15NNO3-保持不变;δ15NDON显著减小。说明采样点4处可能有新的氮源出现。初步估计是由于先前网箱养鱼的积累影响还有高含量的NO3-,低δ15N值的DON输出。 以上的研究结果充分证实了有机质的稳定氮同位素比值的变化能够更加直接地用于追溯有机质的来源以及追踪有机质在湖泊水体中参与的生物地球化学循环作用。
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该论文在贵州及其相邻湖南吉首地区选取了十多个有代表性的碳酸盐红色风化壳,在野外仔细观察的基础上,运用矿物学、土壤物理学及地球化学等研究方法,首次较为系统地阐述了它们的物质来源及成因、矿物学及地球演化特征、稀土元素的超常富集及分异、稀土元素赋存状态等.取得了如下几点认识:1.系统论述了贵州岩溶区红色风化壳的主要物质来源,证实了碳酸盐岩上覆红色风化壳主要物质来源于碳酸盐岩中的酸不溶物,是碳酸盐岩风化后酸不溶物原地残余堆积的结果.2.系统阐述了碳酸盐岩风化壳形成过程中的矿物学与主量元素的演化特征,发现风化作用主要集中于岩-土界面附近进行.3.分析了导致剖面风化强度均匀的原因.4.提出了碳酸盐岩风化壳正反层序的判别方法.5.明确了碳酸盐岩风化壳发育的两阶段模式.6.详细研究了碳酸盐岩风化前缘地球化学碱性障的形成机理.7.初步揭示了岩-土界面稀土元素超常富集和Ce强烈亏损的地球化学机理.8.查明了稀土超常富集层中及剖面中上部稀土元素的赋存状态.9.风化前缘MREE富集现象及其形成机理.
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氟是煤中含量较高的微量元素,大多在20-500mg/kg,平均值为150mg/kg左右。煤在燃烧时,其中的氟化物将发生分解,大部分以日F、SiF_4等气态污染物形式排入大气,不仅严重腐蚀锅炉和烟气净化设备,而且造成大气氟污染和生态环境的破坏。氟是人体所必需的微量元素,但摄入过量则会催患氟斑牙和氟骨症。燃煤污染型氟中毒为我国所独有,导致了近1500万患者,这是人类有史以来最严重的环境污染导致的健康危害事件。因此,根据目前国内外对煤咔l氟的研究进展,研究中国煤中氟的含量、分布及其影响因素;燃煤型氟中毒的环境地球化学特征;选煤脱氟的机理;粮食中氟的分析方法既有理论意义又有现实价值。通过本文的研究,得出以下几点认识:1、通过在全国有计划的系统取样。统一采用当前最有效的分析方法-高温热水解-离子选择性电极法来获得中国煤炭的平均氟含量。与世界煤相比,中国煤含氟量正常,绝大部分(90%)煤的含氟范围为47~347mg/kg,全国煤 氟平均含量为136mg/kg。澄清了长期以来关于中国煤炭高氟的错误认识,为正确计算燃煤的氟排放通量并评价其环境影响提供了较准确的基础资料。2、中国煤中氟含量与灰分显著正相关,表明煤中氟主要以无机矿物形式赋存。3、在本批样品中按变质程度的不同,煤含氟量由低到高依次为贫煤、长焰煤、无烟煤、气煤、焦煤、肥煤、瘦煤和褐煤。煤中的氟主要赋存于无机矿物中,以无机形态赋存的氟不受煤变质程度的影响。从褐煤到无烟煤,煤中的氟含量和煤变质程度之间没有必然的关系,在讨论煤氟含量与变质程度的关系时要考虑氟的赋存形态的影响,以统计分析的方法来研究其间的相互关系时要慎下结论,某些变化趋势不一定就是必然的规律。4、在本批样品中按地质时代的不同,煤中氟含量由低到高依次为早石炭世、中侏罗世、早侏罗世、早二叠世、晚石炭世、中石炭一世、晚侏罗世、第三纪和晚三叠世。煤中的氟含量受物质来源、成煤环境、后期地质地球化学作用等多种因素的影响,而我国幅员辽阔、成煤期多、煤田分布广,而且同地质时代的不同煤矿区(或者地质单元)可以具有相同条件,也可具有不同条件,致使影响含氟量的各种因素大多只具有局部性,造成成煤时代等单一因素的作用可能为其它各种因素的作用所掩盖,对此有必要进行更深入具体的研究。5、拌煤的粘土取自土壤的淀积层,其氟含量非常高。中国煤氟的含量不高,远低于淀积层粘土的氟含量。在燃煤型氟中毒病区通常用粉煤与粘土加水搅拌制成湿的煤泥在无烟囱的炉灶内燃烧。使用烟煤和无烟煤的燃煤型氟病区的氟主要来自于拌煤的粘土。我们突破了长期以来关于氟源是高氟煤的错误认识,这为正确、有效地防治燃煤型地氟病提供了新的思路。6、在石煤污染型氟病区石煤的风化淋溶对水环境、粮食作物的含氟量影响不大,但其燃烧后释放出的的气态、气溶胶态和尘态氟会污染室内空气、粮食、蔬菜和饮水从而导致人体摄氟过量而中毒。改良炉灶,改变在厨房烘烤、存放辣椒的陋习,经常清扫室内,尤其是室内上部灰尘,防止灰尘坠落污染食物、饮水等,对.预防氟中毒有重要意义。7、选煤可降低灰分、硫分,同时还能有效脱除煤中的氟及其他有害微量元素,从而可减少运输成本,降低粉煤灰的收集、处理和处置与有害微量元素的排放控制费用,提高燃烧热效率,符合以预防为主的国家环保政策,要大力倡导。8、我们采集的病区玉米第二次酸浸时浸出液含氟量低于检测限;而辣椒由于含油较多,辣椒油阻碍了氟的浸出,这导致浸泡两、三次后在浸出液中还能检测出氟。在地氟病区采用酸浸一离子选择性电极法测定氟含量时,玉米浸泡一次即可满足研究需要,而对于辣椒则宜进行多次浸泡。一次或多次未浸出的氟含量基本为一个定值,在研究地氟病时不用对此作太多考虑,但在制订粮食的含氟量及人体的摄氟量标准时要将这一部分氟考虑进去。
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贵阳市位于贵州省中部云贵高原东斜坡地带,地处东经106°07′至107°17′,北纬262°11′,至272°22′之间,属东部平原向西部高原的过渡地带,地形地貌多样,海拔高,纬度低,具有亚热带湿润温和型气候的特点,资源丰富,能源充足,自然环境得天独厚。本论文详细研究了贵阳市8046平方公里面积内表层土壤中砷、福、铬、铜、汞、镍、铅、锌8种重金属污染元素的环境地球化学特征,确定了土壤环境地球化学基线,并建立了判别自然的和人为的环境影响的地球化学指标,进而计算污染参数:重金属累计指数和污染程度,在此基础上进行了土壤重金属污染来源分析。取得认识如下:1、贵阳市表层土壤中重金属污染元素的均值、标准差、极值、主要含量区间分别是:砷18·ogmg/kg、11·57 mg/kg、79.30mg/kg、AS95.9%<40mg/kg;福0.302mg/kg、0.363mg/kg、2.620mg/lcg、Cd95.7%<1.000mg/kg;铬75.3mg/kg、37.3mg/kg、271.0mg/kg、Cr95.9%<150.0mg/1cg;铜43.lmg/kg、30.3mg/kg、213.0mg瓜g,Cu94.6o/<100mg/kg;铅43.2mg/kg、31.3mg/kg、318.9mg/kg,Pb95.5%<100.0mg/kg;汞0.222mg/kg、0.531mg/kg、7.030mg/kg,Hg98.2%<1.00Omg/kg;镍38.3mg/kg、14.9mg/kg、102.5mh/kg,Ni95.8%<70mg/kg;锌84.7mkg、49.8mg/kg、385.0mg/kg,Zn93.4%<150.0mg/kg。2、利用相对累计总量分析方法和相对累计频率分析方法确定贵阳市表层土壤中重金属元素的基线值和受人为影响的下限:砷为9.04mk和29.0mg/kg;福为0.068mg/kg和1 .OIOms/kg;铬为44.0mg/kg和100.2mg/kg;铜为18.8mg/kg和68.4mg/kg;铅为14.8mg/kg和70.lmg/kg;汞为0.045mg/kg和0.530mkg;镍为17.0mg/kg和57.0mg/kg;锌46.3mg/kg和112.0mg/kg。3、对贵阳市表层土壤重金属含量进行地质累计指数分析,结果显示贵阳市的表层土壤中:41%未受砷污染,43%的在无污染到中度污染之间,14%的中度污染,只有2%的介于中度污染到强污染之间;40%未受福污染,19%无污染到中度污染之间,14%的中度污染,19%的介于中度污染到强污染之间,7%的强污染,1%的表层土壤强污染到极强污染之间;46%未受铬污染,47%在无污染到中度污染之间,6.8%的中度污染,0.2%介于中度污染到强污染之间;38%未受铜污染,38%在无污染到中度污染之间,22%的中度污染,2%的介于中度污染到强污染之间;18%未受铅污染,47%在无污染到中度污染之间,28%的中度污染,3%介于中度污染到强污染之间;12%未受元素汞污染,37%在无污染到中度污染之间,36%的中度污染,11%介于中度污染到强污染之间,2%的强污染,1%的介于强污染与极强污染之间,1%的极强污染;19.2%未受镍污染,63.7%在无污染到中度污染之间,16.8%的中度污染,0.3%介于中度污染到强污染之间;41%未受锌污染,50%在无污染到中度污染之间,7%的中度污染,2%介于中度污染到强污染之间。4、贵阳市表层土壤中重金属元素含量的污染程度计算显示:砷的污染程度最大为4,27,50.2%的表层土壤未受污染,97%的表层土壤污染程度小于2,总污染程度略大于O,即受到轻微污染;蝠的污染程度最大为12.1,57.9%的表层土壤未受污染,%%的表层土壤污染程度小于4,总污染程度大于。,即受到污染;铬的污染程度最大为2.01,69%的表层土壤未受到重金属元素铬的污染,30.6%的表层土壤受到轻微污染,总污染程度小于O,即未受到污染;铜的污染程度最大为5.09,53.2%的表层土壤未受到重金属元素铜的污染,总污染程度略大于0,即受到轻微污染;铅的污染程度最大为8.11,49.9%的表层土壤未受到重金属元素铅的污染,总污染程度略大于0,即受到轻微污染;汞的污染程度最大为45.87,56.1%的表层土壤未受到重金属元 素汞的污染。总污染程度大于0,即受到污染;镍的污染程度最大为1.56,64%的表层土壤未受到重金属元素镍的污染,总污染程度小于O,即未受到污染;锌的污染程度最大为2.85,77.8%的表层土壤未受到重金属元素锌的污染,总污染程度小于0,即未受到污染。综合考虑8种重金属污染元素,贵阳市40.2%的表层土壤无重金属元素污染,巧%的表层土壤在无污染到轻微污染之间,36.1的表层土壤轻微污染,7.2%的中度污染,1.4%的表层土壤严重污染。5、福和镍只存在较少的污染区域,其余六种元素都存在局部的重金属含量受人为因素影响。砷的污染区域主要集中在筑东部的马场和西部清镇的暗流、王家院等地;铬的污染区域主要集中筑南部的花溪马林、西部的暗流一酒坪等地;铜的污染区域则主要集中在筑南部的燕楼马林处;汞的污染区域分布在筑北开阳双流、筑西北六广以及筑中扎佐三片;铅的污染区域分布在筑东北的宅吉、城关;筑西麦格等处;而锌的污染区则集中在筑东北面的开阳花梨和城关。总体来说,镍、铜的含量是处于最安全的位置,而汞、铅的警戒区域面积很大,几乎函盖了全部研究区域,福次之,砷、锌、铬适中。6、贵阳市表层土壤中重金属污染元素的含量主要与矿山、长期的农业措施和燃煤带来的污染有关。所有重金属含量超标区几乎都对应于矿区,其污染可能来自于母岩,也可能来自矿区生产而导致的“三废”污染。汞、铅、镉的“警戒”区域面积较大,主要是由长期的农业污染造成,特别是磷肥和含污染元素的农药、除草剂等的施用,汞、隔“警戒”区域面积较大的原因还与燃煤后重金属的大气沉降有关。另外砷的污染也和燃煤后大气沉降有关。贵阳市表层土壤没有受到重金属污染元镍的污染。7、在本研究区域内,重金属含量呈现不同含量等级的土类是由于长时间受人为影响的结果,而重金属含量处于单一等级区间的土类则受人为因素影响较小,其含量区间反映了背景值含量范围。在贵阳市的表层土壤中,黄壤、石灰土、水稻土受人为影响较多,石质土、粗骨土、紫色土、黄棕壤受人为影响适中,沼泽土和山地草甸土受人为影响较少。8、本文建议:(1)在乌当区金华镇三铺村、修文县久长镇新隆村、白云区牛场乡小山村、修文县扎佐镇丁官村、修文县大石乡天桥村、开阳县双流镇凉水井村、修文县六广镇滨江村这几个综合污染较为严重的区域采取政府宏观调控手段,指导当地农户进行绿化苗木、花卉等不进入食物链的植物,或者在合适的地方,进行退耕还林,种植生态林。同时建议有关部门在这些区域开展土壤重金属治理工作;(2)在清镇市的暗流一卫城、王家院、水塘以及开阳县马场一哨上等砷含量较高区域种植旱生禾谷类食用籽粒的作物,如小麦、玉米、高粱等,不能种植水生作物和叶菜类作物;在北部开阳双流片、西北部修文六广一大石片、筑中扎佐一牛场片汞含量较高区域推广竺麻的种植;在东北部开阳花梨一城关锌含量较高区域建议农户种植玉米;在开阳的宅吉一龙水、城关和清镇的麦格片区铅含量较高区域,大力发展烟草的种植;在修文久长、大石、开阳城关一马场、清镇麦格、乌当水田一新堡等搞含量较高地区推荐种植豆科食用籽粒作物。9、综合考虑国家《土壤环境质量标准(GB15618一1995)》中规定监测的8种重金属污染元素,污染程度(Cd)的判别指标可以定量化为:Cd≤O:无污染;O<Cd燕1无污染到轻微污染;1<Cd≤5:轻微污染:5<Cd≤10中度污染;Cd>10:严重污染。
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稳定碳同位素作为环境替代指标己经在不同的载体上得到了广泛运用,例如树轮。泥炭、碳酸盐岩等。目前岩溶学者也逐渐开始运用洞穴次生化学沉积物中的稳定碳同位素探讨古气候环境的变迁史,例如植被的更替、大气CO。的浓度变化等。然而由于缺乏该指标在岩溶洞穴系统中形成机理的研究,使得该环境替代指标的运用非常有限。本论文在贵州岩溶地区选择了上覆植被分别为原始森林。灌丛草坡、草坡和石漠化的凉风洞、七星们、犀牛洞、将军们作为研究对象,对岩溶洞穴系统稳定碳同位素的时空演化规律进行了详细的分析,得出以下几点认识:一.洞穴系统稳定碳同位素对地表气候环境的响应通过对4个不同生境洞穴系统的研究,认为洞穴系统稳定碳同位素可以很好地将原始森林植被同其它植被类型区分开;但是不能很好地区分植被退化的过渡类型如灌丛、草坡以及石漠化等。表明石笋的δ13C值在一定情况下可以用来探讨地表植被的变化。但要做更精确的反演需要在加深机理方面的研究。通过同一洞穴不同滴水点的对比研究,发现不同滴水点沉积物的稳定碳同位素存在差异,并且差异还比较大。表明用石笋的δ13C值对古气候环境进行重建时需要慎重考虑滴水点的详细情况。在这种情况下,应该对稳定碳同位素的地球化学过程进行详细研究,尤其应该结合水化学数据对水的运移途径进行深入研究,才能合理地运用稳定碳同位素对洞顶的植被情况进行正确的反演。洞穴滴水和塘中水DICδ13C值和月累积降雨量成相反的变化趋势;地表泉水、土壤水DICδ13C值。土壤CO2、土壤呼吸δ13C值和月累积降雨量的变化在多数时候具有一致的变化趋势。总体而言,洞穴系统水样DICδ13C值对月平均气温的响应不是很明显。只有洞穴塘中水DICδ13C值和月平均气温成相反的变化规律;土壤呼吸CO2δ13C值对月均温响应较为明显:月平均温度越高,土壤呼吸CO2δ13C值越偏轻,反映了温度较高的时候土壤层中的生物活动较强烈。二.岩溶洞穴系统稳定碳同位素的时间演化犀牛洞、将军洞。七星洞10月份植被δ13C值样品的δ13C值比7月份样品的δ13C值偏重。犀牛洞和将军洞土壤空气CO。的δ13C值在8月份出现了一个峰值,以前在清镇红枫湖生态站草地土壤剖面所作的工作8月份的值也同样偏重。在6月份时,凉风洞和七星洞存在一个较为明显的低值,与微生物和植物的强烈呼吸作用有关。土壤呼吸气CO2的δ13C值在6月份出现了明显的低值,和土壤CO。的变化趋势一致。4个洞穴空气CO2的δ13C值在8、9月份有一个低值。七星洞和外界的连通性最好,其洞穴空气CO2δ13C值随时间的变化最不明显,而凉风洞与夕十界的连通性最差,洞穴空气CO2δ13C值的变化幅度最大。土壤水DIC的δ13C值8月份存在一个峰值,在9月份的时候存在一个低值。七星洞地表泉水DIC的δ13C值自6月份开始有逐渐偏重的趋势,到8月份达到一个不甚明显的峰,这个峰值在凉风洞的表层泉中也略有体现。和土壤水比较,地表泉水的不同点在于低值不出现在9月份,而是出现在10月份,相对而言滞后1个月。原因可能是表层泉水所到达的深度比土壤水深;土壤强烈呼吸作用的响应要比土壤水慢。各个洞穴的滴7RDICδ13C值随时间退推移出现了不同的变化规律,可能与滴水的来源和途径不同有关。4个洞穴塘中水DIC的δ13C值统一在7月份达到了最低值;之后DIC的δ13C值逐渐偏重。三.岩溶洞穴系统稳定碳同位素的空间演化植被样不同部位的δ13C值总体上逐渐偏重的顺序是皮一叶一枝一根~干,说明植物不同部位的稳定碳同位素存在差异。随着凉风洞一七星洞一犀牛4同一将军洞的顺序,植被δ13C值逐渐变重;反映了地表植被由C3植物向C3+C4植物的过渡,指示了生态环境由原始森林→石漠化方向的退化。土壤有机碳的δ13C值基本继承地表植物δ13C值的特征。没有发生植被更替上壤剖面上有机碳的δ13C值随着深度的增加逐渐偏重;植被发生了变化的土壤剖面则可能出现与正常规律相反的变化情况。土壤剖面上CO2的δ13C值自地表;句下逐渐变轻,在一定深度后大致趋于稳定;土壤呼吸CO2δ13C值位于土壤CO2δ13C值的变化范围;土壤呼吸CO2δ13C值的变化规律和植被δ13C值的变化在空间上具有一致性。土壤水DIC的δ13C值比土壤CO2值偏重;泉水DIC的δ13C值比土壤水DIC的δ13C值偏重,原因是泉水可能己经渗入到基岩层之后再出露到地表,已经混入了部分基岩无机碳的成分。四个研究洞穴系统盖板基岩的δ13C值变化范围大约在2-3‰之间。凉风洞和犀牛洞不同滴水点滴水的δ13C值相对比较稳定,七星们和将军洞的变化比较大。洞穴塘中水DIC的δ13C值和洞穴滴水相比明显偏重,原因为洞穴塘中水经历了强烈的蒸发作用;满后水比滴前水整体偏重。从洞日往内洞穴空气CO2的δ13C值逐渐偏轻,并且洞穴空气CO2δ13C值继承了洞穴水样DICδ13C值的变化趋势。洞穴化学次生沉积物的δ13值:同一个洞穴中不同滴水点化学沉积物的δ13C值存在差异,但是和滴水DIC的δ13C值相对应,反映了沉积物δ13C值对洞穴滴水DICδ13C值的继承,沉积物δ13C值比滴水DICδ13C值偏重。最新鲜沉积物和比较老的沉积物之间的对比偏轻1-2‰,沉积物中的δ13C值有可能发生沉积期后的变化。
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本文研究范围包括西华山、荡坪半边山、木梓园、大龙山和漂塘五个钨矿床,研究内容着重于花岗岩外接触带微量元素的地球化学特点,试图把内外接触带的研究结合起来,完善本地区的成岩矿理论,并为进一步找矿提供依据。1. 西华山—漂塘地区内外接触带的成矿物质主要来自花岗岩浆。2. 在岩化浆演化过程中,存在着对流分异作用,对流分异作用促使成矿元素向岩体顶部(或边部)富集。3. 角岩化带由隆起的花岗岩体所形成。花岗岩浆和围岩直接的物质交换很少,物质交换主要通过石英脉贯入围岩裂隙,并对围岩扩散交代。4. 在花岗岩或围岩中,石英脉中钨等元素向脉旁运移,而铁、锰质从脉旁向脉中运移,当条件适当时,在脉中沉淀出钨锰铁矿。5. 无论是岩石的矿物含量、结构和构造,还是元素含量,外接触带都没有出现明显分带,其原因主要是受石英脉成分和形态的影响。6. 在本区成矿作用中,氟与钨、锡关系密切,可能氟是主要的矿化剂。7. 外接触带矿床的富贫与相对于花岗岩体的位置有关,花岗岩体上方(或边缘位置较高)的变质岩中含矿较多,相对于花岗岩体位置较低的变质岩中含矿较少。
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为了阐明陨石的冲击压缩效应,我们主要做了以下工作。1、试图从地球物理方面给下地幔物质类似于H群球粒陨石硅酸盐高压相提供证据,并准确标定吉林陨石冲击加载压力和计算冲击温度、残留温度,我们对吉林陨石进行了冲击压缩线的测量和状态方程的研究。2、为了建立显微冲击特征与冲击加载压力之间的对应关系,选用吉林陨石在二级轻气炮上进行人工冲击回收实验。天然样品和每个冲击样品均制作了光薄片,在反光和透光显微镜下进行金相学和岩石学研究。3、为了揭示冲击加热对金属矿物的退火效应,测定了不同加载压力下铁纹石的显微硬度。4、为了查明冲击加载对陨石矿物化学组成的影响,选择了几个有代表性的冲击样品进行铁纹石、镍纹石、陨硫铁、橄榄石和斜方辉石的电子探针分析。5、为了查明某些矿物结构对冲击加载的响应,测试了不同加载压力下冲击样品的红外光谱。6、为了查明冲击加载对普通球粒陨石热释光性质的影响及其程度,测量了几个有代表性冲击样品的天然与诱导热释光。7、为了揭示冲击加载对微量元素含量的影响,用仪器中子活化分析对几个有代表性冲击样品进行了15个微量元素含量的测定。8、最后,根据我们修正的陨石中各种主要显微冲击特征的压标,并利用各种陨石与陨石类似物的冲击压缩曲线,求出了形成这些冲击特征的最小碰撞速度。上述研究内容比较全面地揭示了陨石冲击变质的岩石学、物理和化学效应。表1.1简要地列出了本论文工作的主要内容。
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The aim of this research is to explore the tendency of needs and its influential factors in counselors at present time.Three studies were carried out: study 1 was to find out the tendency of needs and the structure of needs in counselors. Study 2 was to compare the needs between counselors and non-counselors, in which 64 subjects were students majored in psychology but they don’t want to counsel.Study 3 was to initially explore the relationships between the tendency of needs and its influential factors. Studies of the 1 and 3 selected 123 counselors. It was found that: 1. The results of EPPS in counselors: according to comparison between original marks, the number of subjects who range first from high to low was: introspection,change,dominance,nurse,order,succor,affinity=autonomy,achievement,endurance,heterosexuality,deference,aggression=exhibition=abasement ; according to means of original marks, the tendency of needs from high to low was: introspection,achievement,nurse,autonomy,change,succor,endurance,dominance,order,affinity,aggression,exhibition,deference,abasement,heterosexuality. The lower one of the counselors were needs of aggression, exhibition,deference,abasement and heterosexuality,the high one are introspection,nurse and change.The most difference was achievement need. 2. Dilemmas had no significantly different effect on the needs of counselors, but sexuality and age affect them in some factors. There were significant differences in the factors of deference, exhibition and nurse among different ages. Counselors married had higher tendency of obedience, autonomy, introspection, nurse and endurance than those unmarried. 3. The results of EPPS in non-counselors: according to comparison between original marks, the number of subjects who range first from high to low was: endurance,order,change=dominance,autonomy= introspection=nurse,affinity,succor,aggression,achievement,heterosexuality,exhibition=abasement,deference; according to original marks’means, the tendency of needs from high to low was: nurse,endurance,achievement,order,introspection,change,autonomy,dominance,affinity,succor,aggression,exhibition,abasement,deference,heterosexuality. The lower one of the counselors were needs of aggression, exhibition,deference,abasement and heterosexuality,the high one were introspection,nurse and change.The most difference was achievement need. 4. There were significant differences in the needs of abasement and introspection between counselors and non-counselors. Male counselors and non-counselors had significant differences in the factor of abasement. Female counselors had higher tendency of succor needs. 5. The differences of childhood traumas and positive life events were not significant. The positive and negative life events themselves had no significant differences, but negative life events had marginal significant difference between the two groups. 6. The marks of counselors were lower than non-counselors in the factors of neuroticism. 7. Counselors and trainees had no significant differences among other needs、childhood traumas、life events、personality and coping styles except in the deference need. 8. The result of multiple estimation of EPQ , CTQ and EPPS were related.Many specific life events were related with the tendency of many needs. As shown in the research, children’s traumas, characteristic and life events may affect needs chiefly. 9. There were close relation between characteristic and childhood traumas in counselors. Especially the subjects with more childhood traumas had higher tendency of psychoticism, neuroticism and introvision. There were few persons with much high scores on the Childhood traumas in the subjects.Their personality characteristics indicate high extrovision and low psychoticism.Their childhood traumas may affect the shape of sound personality. Conclusion: 1. The most important tendency of needs were introspection,nurse and change. 2. The differences of childhood traumas and life events were not significant between counselors and non-counselors. The marks of counselors were higher than non-counselors in the factors of introspection, but lower in the factor of neuroticism. 3. The main influential factors in counselors of needs were childhood traumas、characteristic and life events.
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The aim of this research is to explore the characteristics of family functioning,personality and their relation to anxiety and depression in high school students. A total of 914 high school students were assessed with The Chinese Family Assessment Instrument and Five -factor Personality Questionnaire and Mental Health Test and Middle School Students Depression Questionnaire. The result indicates, 1. The family functioning and Personality were all significant difference to school, gender, mother’s education and father’s education. 2. There were school, gender, mother’s education and father’s education differences in anxiety of students. 3. There were school, mother’s education and father’s education differences in depression of students. 4. Family functioning were predictive factor directly to anxiety of students, personality serves in part as medium between family functioning and anxiety of students. 5. Family functioning were predictive factor directly to the high school students’ depression, personality serves in part as medium between family functioning and depression of students. 6. The different schools had special features in relation models between family functioning, personality and anxiety of students. 7. The different schools had special features in relation models between family functioning, personality and depression of students.
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In order to analyze the test anxiety of Beijing's high school students, relevant factors affecting test anxiety and how those factors have effect on the test anxiety of those high school students, a cross-sectional study had been conducted among 2,089 students randomly selected from 15 high schools in Beijing, using the Test Anxiety Scale(TAS), Parenting Style Scale (PSS) and Academic Aggregate Graphic (AAG). Five months later, 194 students from one of those high schools were retested with TAS with students remaining anonymous. In the retest, the classes and birth dates of those students were strictly matched. This paper is composed of three parts to examine the issue. The first part examines the test anxiety among high school students in Beijing and establishes the model; the second part conducts a comparative study of issues related to test anxiety and academic performance; the third part examines the factors affecting test anxiety and establishes the model. Results showed that: 1. The reliability and validity of TAS are satisfied and can meet survey requirement. The 25-item version of TAS turned out to have equal or even better performance compared with the original 37-item version. 2. Incidence of test anxiety in high schools of Beijing: 57.9 percent of samples have an overall score at or higher 15. 55 percent of male student samples have a score at or higher than 15 while that for female student samples is 61 percent. A score of 20 refers to fairly serious test anxiety and 31.9 percent of samples have a score over 20. 28.1 percent of the male student samples have a score of over 20 while that for female student samples is 35.9 percent. 3. The effect of grade and sex and the interaction between the two factors are statistically significant. Female students have higher test anxiety than male students and the level of test anxiety varies from grade to grade. 4. Samples are divided into two groups, one with test anxiety and the other without. The academic performance gap between the two groups is very significant. There is a significant negative correlation between academic score and test anxiety. 5. There is a negative correlation between test anxiety and mastery goal orientation and a positive correlation between test anxiety and performance goal orientation. Students with higher academic self-efficiency have lower test anxiety. The more one thinks study is valuable, the lower his/her test anxiety is. Those whose parents communicate smoothly with them have lower test anxiety. Those whose parents have an inconsistent communication style have higher test anxiety. 6. Achievement goal is mediate variable for the effect of lack of values on test anxiety. 7. The indirect effect of introduction of achievement goal and parenting style, including communication, monitoring and communication consistence, on test anxiety is significant. Key words: Test anxiety,reliability, validity, self-efficiency,parenting style,achievement goal orientation, academic values, academic score
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In the period of college, an individual matures rapidly in all aspects. College engineering students are the important parts of undergraduates. The state of an individual’s mental health may affect and even decide his future life and work. The level of the student’s self-concept and the kind of coping styles the students adopt are directly related to their mental health. So, it is significant to study the psychological stress, coping and self-concept of college engineering students for the mental health education and research of college engineering students. Based on overviews of former research, with the China College Student Psychological Stress Scale, the Coping Styles Scale and the Tennessee Self-Concept Scale, 559 college engineering students were investigated to explore the characteristics of and the relationship between the psychological stress, coping styles and self-concept of college engineering students. The results showed: 1. The stresses of learning, living and daily hassles were the main psychological stresses of college engineering students. There were significant differences in psychological stress between students from the countryside and those from urban areas, between needy students and non-needy students, between single-parent students and non-single-parent students, among students from different grades, with different academic achievements and of different postgraduate targets, between student party members and non-party members, between student cadres and non-cadres. However, there were no significant differences between male and female, between those from single-child families and from multiple-child families. 2. The coping styles of solving problem, seeking help and rationalization were the main coping styles of college engineering students. There were significant differences in the coping styles between needy students and non-needy students, among students from different grades, with different academic achievements and of different postgraduate targets, between student party members and non-party members, between student cadres and non-cadres. However, there were no significant differences between students from the countryside and from urban areas, between male and female, between single-parent students and non-single-parent students, between those from single-child families and from multiple-child families. 3. The self-concept of college engineering students was positive in general. There were significant differences in self-concept between students from the countryside and those from urban areas, between male and female, between needy students and non-needy students, between single-parent students and non-single-parent students, among students from different grades, with different academic achievements and of different postgraduate targets, between student party members and non-party members, between student cadres and non-cadres. However, there were no significant differences between those from single-child families and from multiple-child families. 4. The psychological stress had significantly negative correlation to the immature coping styles, and had partial correlation to the mature coping styles. Coping style has significant predictability on psychological stress. 5. The positive factors of the self-concept had significantly negative correlation to psychological stress, but self-criticism had positive correlation to psychological stress. There are significant differences between high self-concept students and low self-concept students for psychological stress. Self-concept has significant predictability on psychological stress. 6. The positive factors of the self-concept had significantly negative correlation to the coping styles of self-blame, illusion, avoidance, and rationalization, but had significantly positive correlation to the coping style of solving problem and seeking help. Self-criticism had significantly negative correlation to the coping styles of self-blame, illusion, avoidance, and rationalization. There are significant differences between high self-concept students and low self-concept students for coping styles. Self-concept has significant predictability on coping styles. 7. The self-concept of college engineering students had an effect on psychological stress by coping styles. However, the effect by the immature coping styles was higher than that to the mental health directly, and the effect by the mature and mixed coping styles was slighter than that to the mental health directly. According to the results, improving the college engineering students’ self-concept level and establishing right self-concept, developing the middle school student’ active coping styles and overcoming the negative coping styles are essential and important to the college engineering students’ mental health and provide useful clues for the psychological education of the college engineering students.
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心理学对演绎推理机制的研究仍有争议,存在心理模型理论和心理逻辑理论之争,因此,从不同角度探查演绎推理的过程显得十分必要。本研究以小学儿童为研究对象从时间序列关系推理的角度来阐释推理是基于心理模型的还是基于心理逻辑的,从而为时间序列关系推理机制的研究提供更多的实验证据。 本研究采用实验法系统探查了8-12岁儿童对时间序列关系的推理能力,以推理的正确率和策略为研究指标,探查了在计算机和纸笔条件下儿童推理能力发展的一般过程及其特点,并试图揭示含有不同关系词的前提、推理前提数量以及问题类型(有确定答案的传递问题、有确定答案的非传递问题、无确定答案的非传递问题)对儿童推理能力发展的影响。 主要研究结果如下: (1)总体而言,儿童时间序列关系推理能力随年龄而发展。 计算机条件下,儿童对有确定答案的传递问题的推理能力的发展趋势因实验任务而异:8岁组与10岁组儿童对含有不同关系词前提的推理能力差异显著;8岁组与12岁组儿童在不同推理前提数量下的推理能力差异显著。8岁组与10岁组儿童对无确定答案的非传递问题的推理能力差异显著。 纸笔条件下,8岁组与10岁组儿童对有确定答案的传递问题、有确定答案的非传递问题的推理能力差异显著,对无确定答案的非传递问题的推理能力在12岁时仍处于较低水平。 (2)推理的前提数量对儿童时间序列关系推理能力发展的影响因问题类型而异。有确定答案的传递问题下,前提数量不是影响推理成绩的主要因素;有确定答案的非传递问题下,儿童对4前提的推理成绩显著高于对5前提的推理成绩。 (3)含有不同关系词的前提对儿童时间序列关系推理能力的发展有影响。儿童对含有“在……之后”前提的推理成绩高于对兼含“在……之前”和“在……之后”前提的推理成绩,二者均高于对含有“在……之前”前提的推理成绩。 (4)推理的问题类型对儿童时间序列关系推理能力的发展有影响。儿童对有确定答案的传递问题的推理成绩高于对有确定答案的非传递问题的推理成绩,对有确定答案的非传递问题的推理成绩高于对无确定答案的非传递问题的推理成绩。 (5)儿童采用自身经验策略、位置序列策略、逻辑排序策略和模型建构策略等4类策略来进行时间序列关系推理。逻辑排序策略和模型建构策略是儿童在3类问题上均使用的策略。 (6)计算机和纸笔条件下儿童的推理能力以及推理策略类型的使用无显著差异,两种测验条件下儿童推理能力的发展表现出大体相同的趋势。 (7)儿童对不同类型问题推理成绩的差异符合心理模型理论关于推理难度的预期。但是,推理的心理模型理论不能完全解释儿童的推理过程。