纵向岭谷区公路沿线土壤表层重金属空间分异特征

以纵向岭谷区内云南省境内的丽江～景洪公路沿线作为案例研究区,根据路段所处的地理位置、公路等级、修建的时段,将其分为北段、中段和南段。通过公路沿线94个样点的土壤表层重金属全量分析,研究了土壤重金属沿公路的纵向、横向和垂向分异特征性。在纵向上,Cu,Zn,Pb,Cr,Cd,As,Mg和Mn等8种重金属全量存在北段高于中段和南段的特征;相关性分析结果表明公路建设对铅、镉、锌的纵向差异存在一定影响。横向空间分异性显示,虽然在不同的土壤种类和利用方式下,土壤重金属含量值差异很大,但公路沿线重金属与公路距离之间存在显著相关关系,表明公路对横向的空间分异性存在决定性影响,影响带宽度约为50m垂向分析结果表明,自然土壤中重金属的垂向分异性不如横向分异明显,仅显示在近公路处有重金属富集现象;而在公路施工区,受人工护坡等工程的局部影响,垂向分异性不显著。     

205国道两侧农田土壤和水稻叶片及糙米中重金属含量的空间分布特征

对205国道无林带典型路段东西两侧200 m范围内的农田表层土壤、稻(Oryza sativa L. )叶及糙米中Al、Cd、Cr、Cu、Fe、Ni、Pb、Zn和As的含量及空间分布规律进行了分析研究.结果表明,205国道两侧农田表层土壤中Cd、Cr、Cu、Ni、Pb和Zn的含量达到土壤环境质量一级标准(GB15618-1995),As含量超过土壤环境质量三级标准.西侧表层土壤中的Al、Cr、Fe、Ni、Zn和As含量,稻叶中的Al、Cd、Cr、Fe和Ni含量及糙米中的Al、Cd、Cr、Cu、Fe和Ni含量均比东侧高,表明路西侧受汽车尾气扩散沉降影响比东侧明显,并与该路段主风向为偏东风有关;西侧表层土壤中的Ni和Zn含量及东侧表层土壤中的Cd含量、西侧稻叶中的Al和Zn含量、西侧糙米中的Fe含量和东侧糙米中的Al含量均有随路侧距离增加而显著递减的规律,负相关关系显著或极显著;稻叶和糙米中某些重金属的含量有明显的峰值区域,均位于路侧10～20 m区域内,并与土壤中的含量有显著或极显著的正相关关系;在糙米中未检出As,且Al、Cd、Cr、Cu和Zn含量均未超出国家食品卫生标准,但部分样本Ni和Pb含量略有超标.主成分分析结果显示,稻叶中的Pb主要来源于土壤,而稻叶中其他重金属含量明显受到公路环境污染物扩散沉降影响.研究结果显示,重金属元素已在205国道两侧的农田表层土壤中显著累积,其中As的积累最严重;稻叶和糙米中重金属的含量水平明显受到公路汽车尾气扩散沉降的影响,且扩散沉降集中在距离公路边缘10～20 m的区域内.     

大兴安岭森林土壤重金属含量空间变异与污染评价

重金属是危害森林生态健康的主要污染物之一,迄今有关大兴安岭森林土壤重金属含量、空间变异和污染程度鲜见报道。本文通过野外调查采样,应用GIS空间分析技术,结合经典重金属污染评价方法,分析了大兴安岭森林土壤Cd、Cr、Pb、Cu、Zn、Ni、Hg及As含量的空间变异与污染程度。结果表明:(1)研究区8种重金属含量具有中等空间异质性,变异系数在16.67%~35.39%。Cd、Cr、Pb、Zn、Hg、As的块金值/基台值[C0/(C0+C)]25%,其空间变异主要由母质、地形等结构性变异引起,Cu和Ni的C0/(C0+C)在25%~75%,即非结构性因素人类活动对二者的影响较大。土壤重金属含量呈斑块状、条带状和岛状分布。(2)大兴安岭森林土壤8种重金属含量主要表现为累积的特征。8种重金属含量的平均值与最大值均未超过《国家土壤环境质量标准》(GB 15618—1995)二级标准限值,其中Cu、Zn、As的最大值超过一级标准,而其他5种元素的最大值均未超过一级标准。(3)地积累指数表明,土壤Cr、Pb、Ni无污染风险,其他5种元素污染风险较低。内梅罗综合污染指数表明,土壤整体质量已经处于轻污染状态。单因子潜在生态风险指数分析表明,Cu、Ni、Pb、Cr、Zn、As不具有潜在生态风险,Hg、Cd的部分样点的单因子生态风险指数Eri值存在生态风险,其中Hg的个别特征点已经达到Ⅲ级(中等风险)水平;潜在生态风险指数表明,研究区80%的样点无潜在生态风险,20%样点处于一般生态风险水平。     

横断山区草本沼泽湿地水体氮含量空间分布特征

草本沼泽是横断山区重要的湿地类型,为探明横断山区草本沼泽湿地水体中总氮、硝氮和氨氮的空间分布特征及其控制因素,于2014—2017年在横断山区对典型草本沼泽湿地开展水样采集和分析工作,同时收集降水量、地表大气温度、水温、水深、人口数量、GDP、家畜数量等环境数据。结果表明：1）横断山区草本沼泽湿地水体中总氮含量表现出明显的纬向地带性和垂直地带性：总氮含量随纬度和海拔增加而下降,水温是控制这种地带性特征的主要因素。同时,随经度增加,水体中总氮含量也显著增加,社会经济发展因素是导致这种分布特征的主要原因;2）横断山区沼泽湿地水体中硝氮和氨氮含量在海拔梯度上的变化趋势不明显;3）随经度和纬度增加,沼泽湿地水体中硝氮含量逐渐增加,导致这种现象的主要原因是水深和水温;4）随经度增加,沼泽湿地水体中氨氮的含量逐渐增加,但氨氮含量与自然环境因素和社会经济发展因素均无显著相关性。     

海河低平原区农田重金属含量的空间变异性——以河北省肥乡县为例

随着工业和农业的快速发展,农田受到重金属污染的压力越来越大,其土壤环境质量的及时监测和掌握重金属在其空间的变异规律对农业生产具有十分重要的意义。利用地统计学和GIS技术对海河低平原区（肥乡县）农田土壤耕层（0—20Cm）8种重金属含量空间变异性进行了研究。结果表明：去除异常值后,8种重金属含量都符合正态分布,且其含量算术平均值未超过国家土壤环境质量二级标准。通过变异函数分析,Ph和Cr具有纯块金效应,Cu和Zn符合指数模型,Ni和Cd符合球状模型,地和As符合带基台值的线性模型。在该地区以2．0km为取样间距较大,以后调查时应该缩小间隔。Zn和Cd的空间变异性受人为因素影响较小,而Cu、Ni、Hg和As的空间变异性受人为因素影响较大,Ph和Cr在整个研究尺度上具有恒定的变异。Cu、Zn、Ni、Hg、As和Cd的变程差异较大,在2．5—13．7km之间。通过普通kriging法局部插值,Cu、Zn、Ni和As含量由西南部向东北部含量逐步升高,但是Hg却表现出相反的分布趋势。这将为当地正在开展的优势农产品区域布局规划提供理论依据。     

围垦对辽东湾北部滨海湿地土壤重金属含量的影响及生态风险评价

围垦历史与围垦方式被认为是人类对滨海湿地生态系统干扰的主要因素。选取辽东湾北部区作为研究区,采集129个表层土壤样品（0-20 cm）,测定土壤理化性质（盐分、pH、土壤颗粒组成、土壤有机碳、硝态氮、速效磷）和重金属元素（Fe、Mn、Cu、Cr、Cd、Ni、Zn、Pb）含量;运用多元统计和反距离权重插值方法揭示研究区土壤重金属元素的来源与空间分布特征,最后利用Hakanson潜在生态风险指数法对重金属的潜在生态风险进行评价。结果表明：①6种重金属表现为彼此的显著正相关（P<0.01）。除Pb外,Cd、Cr、Cu、Ni和Zn的浓度与土壤有机碳、黏粒、粉粒含量呈极显著正相关（P<0.01）,而与砂含量呈极显著负相关（P<0.01）。②化工、造纸、石油开采及加工等工业活动可能引起Cr、Cu、Ni和Zn的富集,持续的农业施肥和农药使用可能会增加土壤中Cd、Pb的含量。③围垦初期（1990s）,土壤侵蚀和淋洗脱盐对土壤重金属分布具有显著影响。随着开垦年限的延长（1960s）,持续的农业施肥、工业活动（如造纸、石油开采）和城市扩建,都大大增加了土壤重金属含量的累积。④不同的围垦方式影响下,除Fe标准化的Cd和Pb在水产养殖区有较高的浓度外,Fe标准化的Cr、Ni、Cu和Zn的浓度均在自然区域（滩地和芦苇）高于人类活动区域（水产养殖、耕地、建设用地）。⑤综合潜在生态风险指数平均值为325.69,表现为极强的生态风险程度,其中Cd表现为极高生态风险的采样点比例为46.51%,是造成区域重金属污染的主要贡献元素,特别是在水产养殖和农业地区。     

基于Hyperion影像植被光谱的土壤重金属含量空间分布反演——以青海省玉树县为例

本研究主要探讨了利用Hyperion影像植被光谱估算土壤重金属含量的可行性.以野外采集的三江源区玉树县48个表层土壤样品As、Pb、Zn、Cd实验室测定含量值,以及从两景Hyperion影像提取的48个土壤样本点相应的176个植被光谱反射率波段及构建的5种植被指数为数据源,利用偏最小二乘回归方法(PLSR)建立土壤各重金属含量与上述两套Hyperion影像上提取的变量之间的估算模型.模型分别为176个植被光谱反射率波段与土壤各重金属含量间的估算模型(植被光谱反射率模型),和以5种植被指数作为自变量,与土壤各重金属含量建立的估算模型(综合植被指数模型).运用验证样本的4种重金属元素实测含量值的标准差与均方根误差的比值(RPD)作为检验标准,As、Pb两种模型RPD均小于1.4,不具备粗略估算能力;Zn、Cd两种模型RPD分别为1.53、1.46与1.46、1.42,均具备粗略估算能力.根据上述结果将Zn的光谱反射率估算模型与Hyperion影像相结合反演得到土壤重金属Zn含量的空间分布,Zn含量在214国道、308省道和乡镇附近偏高,主要受到较强的人类活动影响.表明运用Hyperion高光谱影像植被光谱反射率可以间接估算土壤Zn、Cd元素含量.     

尖叶走灯藓(Plagiomnium cuspidatum ) 叶绿素荧光对复合重金属胁迫的响应

利用快速叶绿素荧光动力学技术研究了Cu^2＋、Zn^2＋、Cd^2＋、Pb^2＋四种重金属离子复合污染下尖叶走灯藓Plagiomnium cuspidatum（Hedw.）T.Kop.叶绿素荧光动力学以及叶绿素含量的变化。结果显示,重金属胁迫导致尖叶走灯藓PSII反应中心的最大光化学效率（Fv/Fm）、光合机构电子传递的量子产额（ETo/ABS）、捕获的激子将电子传递到电子传递链中超过QA的其它电子受体的概率（ETo/TRo）、单位叶面积的反应中心的数量（RC/CSo）降低。重金属胁迫也显著降低尖叶走灯藓植物体叶绿素a、叶绿素b、总叶绿素含量以及Chla/b的值,降低的程度与重金属浓度和胁迫时间有关。尖叶走灯藓可以耐受10μmol/L浓度的复合重金属污染,在10μmol/L浓度范围内,尖叶走灯藓PSII最大光化学效率Fv/Fm、单位面积有活性反应中心的数目RC/CSO、捕获的激子将电子传递到超过QA的其它电子受体的概率ETO/TRO以及用于电子传递的量子产额ETO/ABS等与对照相比均无明显变化,表明在此浓度范围内,重金属不会对尖叶走灯藓的光合器官造成伤害。50μmol/L和100μmol/L浓度的重金属则造成光合系统的不可逆损伤。     

雪松松针多糖超声波酶法提取及其抗氧化性

为优化雪松松针多糖超声波酶法的提取工艺,并研究多糖结构及其抗氧化性。通过响应面法分析确定最佳提取参数为:3. 0 g松针粉末,液料比20∶1(m L∶g),提取温度80℃,超声功率560 W,超声时间47 min,纤维素酶用量12 FPU/g原料,提取两次,多糖得率高达10. 39%。采用高效液相色谱、红外光谱和核磁共振光谱等对松针多糖进行了结构表征,松针多糖以β-糖苷键为主要连接方式,并由葡萄糖、果糖、阿拉伯糖和半乳糖等单糖组成。体外抗氧化性研究结果表明:松针粗多糖对羟基自由基(·OH)和1,1-二苯基-2-三硝基苯肼自由基(DPPH·)的清除能力远高于纯化多糖,呈现出良好的量效关系,粗多糖对·OH和DPPH·的半抑制浓度IC50分别为0. 47 g/L和0. 076 g/L。     

Pollen production,microsporangium dehiscence and pollen flow in Himalayan cedar (Cedrus deodara Roxb. ex d. Don)

Microsporangium dehiscence, pollen production and dispersal were studied in Himalayan cedar (Cedrus deodara) during 1998 and 1999. Microsporangium dehiscence showed diurnal periodicity and was found to be related to air temperature and relative air humidity, with a strobilus taking 2 d to dehisce completely in warmer conditions and 3 d in cooler ones. The frequency of flowering in C. deodara was highly variable during the two successive years; however, cyclical production of pollen grains was observed in 50% of the trees. The maximum concentration of pollen grains in the air was found between 1200 and 1600 h, and this period was also noted to be the best time for pollination. Studying migration of pollen grains from isolated single trees in three directions showed that migration was not uniform in all directions. Long-distance transport of pollen grains was observed in the downhill direction. However, in the uphill and horizontal directions grains could travel only up to 97.5 and l95.1 m, respectively, and the frequency of pollen grains to the source frequency at these distances was only 1.9 and 2-5%, respectively. The results suggest that an isolation barrier of 190 m may be considered as a minimum for the management of deodar seed orchards.     

迁安市农田重金属含量空间变异性

利用地统计学和GIS相结合的方法,对河北省迁安市农田土壤耕层（0～20 cm)8种重金属含量的空间变异性进行了研究.结果表明,农田中8种重金属含量均值未超过土壤环境质量(GB15618-1995)二级标准,属于中等变异.Cu、Zn、Ni、Cr和As含量的变异函数理论模型符合指数模型,空间相关程度强;Hg和Cd含量的变异函数理论模型符合球状模型,空间相关程度中等;Pb含量具有纯块金效应,空间相关程度弱.在整个研究尺度上,Pb含量具有恒定的变异,其余7种重金属含量由空间自相关部分引起的空间变异性起主要作用,空间相关距离为11～20 km.用普通Kriging方法对Cu、Zn、Ni、Cr、Hg、As和Cd含量空间局部插值表明,北部山地重金属含量较高,而中部盆地重金属含量较低.     

Resistance characteristics of Cedrus deodara and Sabina chinensis to heavy metal accumulation under different atmospheric conditions

Cedrus deodara and Sabina chinensis are widely planted in North China. The needles of C. deodara and S. chinensis were sampled in the urban, suburban, and rural districts of Tianjin where the atmospheric conditions are significantly different according to the environmental monitoring results. The Cu, Mn, Zn, and Pb concentrations in the samples were examined via ICP. The resistance indexes, and the malonic aldehyde (MDA), soluble sugar, and free proline levels were also determined. The Pearson coefficients between the resistance indexes and the heavy metal contents were analyzed to compare the two plants abilities to accumulate heavy metal and their resistance characteristics. The results indicated that the heavy metal concentrations had the following significant trend: urban areas > suburban areas > rural areas. In urban areas, the Mn, Zn, and Pb concentrations in C. deodara were as high as 2024.77 mg·kg^? 1, 2397.07 mg·kg^? 1, and 130.07 mg·kg^? 1, significantly higher than in S. chinensis. The Mn, Zn, and Pb concentrations in C. deodara were extremely significantly positively correlated (P < 0.01), but no significant correlations were noted in S. chinensis. The MDA, soluble sugar, and free proline concentrations in C. deodara increased as the heavy metal contents rose along the urban–rural gradient, and were positively correlated with the plant heavy metal contents. They were much higher than the contents in S. chinensis where no differences were noted among the sampling sites. In conclusion, the heavy metal resistance methods used by C. deodara and S. chinensis are different. C. deodara could absorb and accumulate many heavy metals, mainly through increased physiological resistance to stress. In contrast, S. chinensis resistance relied on avoiding contact with the metals and by reducing absorption. These differences are associated with the biological characteristics of C. deodara and S. chinensis, and are closely connected with their coniferous and morphological differences.     

Spatial variability in nutrient concentration and biofilm nutrient limitation in an urban watershed

Nutrient enrichment threatens river ecosystem health in urban watersheds, but the influence of urbanization on spatial variation in nutrient concentrations and nutrient limitation of biofilm activity are infrequently measured simultaneously. In summer 2009, we used synoptic sampling to measure spatial patterns of nitrate (NO₃ ⁻), ammonium (NH₄ ⁺), and soluble reactive phosphorus (SRP) concentration, flux, and instantaneous yield throughout the Bronx River watershed within New York City and adjacent suburbs. We also quantified biofilm response to addition of NO₃ ⁻, phosphate (PO₄ ³⁻), and NO₃ ⁻ + PO₄ ³⁻ on organic and inorganic surfaces in the river mainstem and tributaries. Longitudinal variation in NO₃ ⁻ was low and related to impervious surface cover across sub-watersheds, but spatial variation in NH₄ ⁺ and SRP was higher and unrelated to sub-watershed land-use. Biofilm respiration on organic surfaces was frequently limited by PO₄ ³⁻ or NO₃ ⁻ + PO₄ ³⁻, while primary production on organic and inorganic surfaces was nutrient-limited at just one site. Infrequent NO₃ ⁻ limitation and low spatial variability of NO₃ ⁻ throughout the watershed suggested saturation of biological N demand. For P, both higher biological demand and point-sources contributed to greater spatial variability. Finally, a comparison of our data to synoptic studies of forested, temperate watersheds showed lower spatial variation of N and P in urban watersheds. Reduced spatial variation in nutrients as a result of biological saturation may represent an overlooked effect of urbanization on watershed ecology, and may influence urban stream biota and downstream environments.     

Age-related drought sensitivity of Atlas cedar (Cedrus atlantica) in the Moroccan Middle Atlas forests

Age-related tree responses to climate change are still poorly understood at the individual tree level. In this paper, we seek to disentangle the relative contribution of tree age to growth decline and growth–climate relationships in Atlas cedar (Cedrus atlantica Manetti) trees at the Middle Atlas Mountains, northern Morocco. Dendrochronological methods were applied to quantify growth–climate relationships using tree-ring width indices (TRWi) calculated for cedars of two contrasting age groups (old trees, age ≥150 years; young trees, age <150 years). TRWi–climate relationships were assessed at the site and tree levels by using response functions and linear mixed-effects models, respectively. Growth of the studied Atlas cedars was negatively affected by recurrent droughts and by the steep temperature rise since the 1970s. Response functions and mixed-effects models indicated that the decline in tree growth was mainly explained by diminishing precipitation. The negative association between cedar growth and temperature was stronger in old than in young trees. Vulnerability to temperature-induced drought stress in old cedar trees may lead to an impending growth decline. We argue that the age dependence of growth sensitivity to drought must be quantified and considered at the individual tree level when predicting the future dynamics and persistence of cedar forests in the Moroccan Middle Atlas.     

沈阳城市土壤全钾和碱解氮的空间变异性

采用地统计学和地理信息系统（GIS）相结合的方法研究了沈阳城市土壤全钾、碱解氮2种土壤养分的空间变异性.结果表明：全钾的最佳拟合模型为指数模型,碱解氮的最佳拟合模型为高斯模型;其块金值/基台值［C₀/(C₀+C)］分别为10.65%和17.96%,说明沈阳城市土壤全钾和碱解氮的空间相关性较强,其空间变异主要是由结构性因素引起的.通过克立格插值对沈阳城市土壤全钾和碱解氮的空间分布特征进行分析发现：全钾的空间分布没有明显的规律性;碱解氮的空间分布则为周边高、城区中部低.     

Effects of endogenous ABA levels and temperature on cedar (Cedrus libani Loudon) bud dormancy in vitro

Axillary and apical buds of in-vitro-propagated cuttings of Cedrus libani are unable to burst at 24 °C, but this inhibition was overcome at 30 °C. Here we have used cedar microcuttings to investigate whether the levels of endogenous hormones vary with bud dormancy and temperature. We analysed the levels of abscisic acid, indole-3-acetic acid, zeatin, isopentenyladenine and their major metabolites using HPLC purification and fractionation of the samples coupled to an ELISA method for hormonal quantitation involving several antibodies elicited against each hormonal family. Abscisic acid levels in microcuttings with dormant buds were higher than those in microcuttings with growing buds. At 24 °C, needles accumulated more abscisic acid than at 30 °C. In addition, when needles were removed, but growth release was achieved at 24 °C. Abscisic acid supplied at 30 °C induced the formation of dormant buds. These results suggest that abscisic acid accumulation in the needles can explain the bud dormancy of cedar microcuttings at 24 °C. Received: 14 November 1997 / Revision received: 16 January 1998 / Accepted: 5 May 1998     

基于GIS和地统计学的稻田土壤养分与重金属空间变异

以湖南省长沙县北山镇3.56 hm²的水稻田为研究区域,基于网格法(25 m×25 m)等距离取样,采用GIS和地统计学相结合的方法,对研究区土壤耕作层(0～20 cm)的pH值、有机质、全氮、速效磷、阳离子交换量(CEC)与3种典型重金属元素Cd、As、Pb的空间变异特征进行了定量分析.结果表明: 研究区内土壤pH值和Pb含量表现为弱变异,其他各项指标均表现出中等强度变异,变异顺序的大小为:速效磷＞Cd＞全氮＞有机质＞CEC＞As＞Pb＞pH.半方差检验结果表明,有机质、速效磷、As的半方差函数的最佳拟合模型为指数模型;pH、全氮、CEC、Cd和Pb的最佳拟合模型为球状模型;除CEC呈中等空间相关外,其余指标均表现出强烈的空间相关.克里格插值分析表明: pH、全氮、CEC、Pb呈斑块状分布;有机质、速效磷、Cd、As呈块状和带状分布.植被、地形和人类活动是造成研究区土壤养分与重金属格局差异的主要因素.相关性分析表明,部分土壤养分与重金属含量的相关性达到显著水平,其中pH与有机质、Cd与Pb的相关性达到了极显著相关水平.     

Phytophthora spp. associated with the decline of Cedrus deodara in Nanjing,China

Recently, 3-year-old seedlings of Cedrus deodara in Nanjing, China developed root rot, crown rot, chlorosis and defoliation, often resulting in death. Two species of Phytophthora were isolated. One was identified as A2 mating type of P. cinnamomi Rands while the other failed to produce sex organs in single or dual cultures and was tentatively assigned to P. drechsleh Tucker. Their pathogenicity was confirmed by re-inoculation and re-isolation.