物种和基物偏好对河北太行山区六种地衣的元素含量的影响

为了解物种和基物偏好对地衣元素水平的影响,测定了采集于河北太行山区6个地点的6种地衣体内的16种元素（Al、Ba、Cd、Cr、Cu、Fe、Mn、Mo、Na、P、S、Sc、Sr、Ti、V和Zn）的含量。这6种地衣包括3种石生地衣（鸡冠胶衣Collema cristatum、中国石黄衣Xanthoria mandschurica和淡腹黄梅Xanthoparmelia mexicana）,2种土生地衣（莲座石蕊Cladonia pocillum和石果衣Endocarpon pusillum）,及1种树生地衣（毛边黑蜈蚣衣Phaeophyscia hispidula）。主成分分析（PCA）和费里德曼双向秩方差分析（Friedman检验）结果显示,物种和基物偏好对地衣体内元素含量的影响显著,而地点的影响不显著。树生地衣累积的大气源元素（P、S和Zn）高于土生和石生地衣。土生地衣体内的地壳源元素（Al、Ba、Fe、Mn、Mo、Na、Sc、Sr、Ti和V）和大气源元素Cr的含量最高。石生地衣的大气源元素（P、S和Zn）含量近于土生地衣,但地壳源元素含量较低;3种石生地衣在这些元素的含量方面差异不大。这些结果表明以地衣化学组成监测大气元素沉降的研究需慎重考虑物种及基物偏好的影响。     

山西太行山区两种地衣——中国石黄衣和黄烛衣的元素含量差异

地衣在大气元素沉降的生物监测研究中应用广泛,但地衣物种之间的元素组成差异会对元素的环境输入评估产生干扰。为摸清元素含量在2种叶状地衣(石生的中国石黄衣Xanthoria mandschurica,XM;树生的黄烛衣Candelaria fibrosa,CAF)之间的差异及其可能的生态学原因,用电感耦合等离子体质谱法(inductively coupled plasma mass spectrometry,ICP-MS)测试了采自山西太行山区长治盆地及其周边共3个地点的地衣样品中的51种元素。结果显示,40种元素的含量在地衣间差异较大,其中36种元素(Al、Ba、Be、Bi、Ca、Ce、Cs、Dy、Er、Eu、Fe、Gd、Ge、Ho、La、Li、Lu、Mn、Na、Nb、Nd、Ni、Pb、Pr、Sc、Si、Sm、Sr、Tb、Th、Ti、Tm、U、V、Y和Yb)在XM中含量较高,可能归因于其受大气干沉降更大且更易受本地岩石地球化学的影响,而CAF受冠层截留作用的影响更大;其中4种元素(K、P、S和Zn)在CAF中含量较高,可能与冠层淋溶作用有关。另外11种元素(As、B、Cd、Co、Cu、Hg、Mg、Rb、Sb、Se、Tl)在2种地衣之间的含量差异较小。大气元素沉降的地衣监测法需考虑地衣物种、基物的地球化学特征和植被的影响。     

三种石黄衣的共生菌化学多样性及其系统生物学意义

本文对丽石黄衣(Xanthoria elegans)、中国石黄衣(X.mandschurica)和刺盘石黄衣(X.alfredi)的共生菌,尤其是刺盘石黄衣共生菌的分离培养物进行了首次研究。对于上述三种地衣体及其共生菌的化学物质进行了比较分析。研究与分析结果表明,三种石黄衣地衣体化学物质,即蒽醌类化合物完全一致。此外,Lindblom从15种北美石黄衣地衣体中检测出了彼此一致的5种葸醌类化合物。因此,该作者认为石黄衣属的蒽醌类化合物不具有种级分类学意义。本文的实验结果也证实了这一观点。但是,本文对于通过子囊孢子释放法获得的中国三种石黄衣共生菌的化学物质进行了检测和分析,其结果呈现出比较丰富的多样性。其中刺盘石黄衣共生菌化学物质与丽石黄衣和中国石黄衣共生菌所含的化学物质存在明显差异。因而,刺盘石黄衣共生菌化学物质在该种地衣的鉴定中具有重要的参考价值。此外,文章亦检测和分析了丽石黄衣的10株共生菌化学物质。供试菌株均在相同培养条件和培养时间下获得。其化学物质的TLC图谱,除Nos．5,7,及10稍有差异外,几乎完全一致。由此看来,它们稳定性也是比较明显的。上述结果提示我们,在地衣系统生物学研究中,除了对于地衣体化学物质进行常规检测与分析之外,对于分离培养的各种地衣共生真菌化学物质的检测与分析也是必不可少的。因为,地衣系统生物学归根结底是地衣型真菌的系统生物学。在上述三种石黄衣共生菌化学物质以及其地衣体化学物质的比较研究中,并未发现丽石黄衣和中国石黄衣之间的明显差异。因此,有理由怀疑,这两种地衣究竟是不同的物种,抑或是同一物种的多态型？对此,我们将在今后研究中作进一步探讨。     

山西省太岳山区有害元素大气污染的地衣(丽石黄衣)监测

山西太岳山区大气元素沉降研究较少。为摸清该区域大气污染水平及其受盆地的可能影响,以ICP-MS法测定采自15个样点的丽石黄衣(Xanthoria elegans)地衣体内7种常见有害元素(As、Cd、Cu、Pb、S、Sb和Zn)的含量,并进行相关性分析、方差分析和聚类分析。结果显示:该区域元素含量一般高于"清洁区",但低于"严重污染区"的相应数据,表明太岳山区具有一定程度的大气污染。聚类分析将15个样点分为两类,两类样点在距盆地距离(distance from the nearest basin, DFNB)和多数元素的含量方面均差异显著,近盆地区(DFNB=13.7±7.987 km)中的6种元素(As、Cd、Cu、Pb、Sb和Zn)含量均显著高于远盆地区(DFNB=32.5±6.062 km), 5种元素(As、Cu、Pb、Sb和Zn)的含量与DFNB之间的负相关关系显著(r≤-0.59; P≤0.02),表明山区内部的大气质量受盆地地区的大气污染物传输的影响。S含量的空间异质性低(变异系数CV10%),和DFNB的相关性及在近盆地区和远盆地区之间的差异均不显著(P0.05),但仍随DFNB增加呈下降趋势,表明盆地人类活动所释放的S可能主要是以更易于扩散的气态形式向山区传输的。本研究结果表明丽石黄衣是太岳山区大气有害元素污染的良好监测生物。     

三种石黄衣的共生菌化学多样性及其系统生物学意义

本文对丽石黄衣(Xanthoria elegans)、中国石黄衣(X. mandschurica)和刺盘石黄衣(X. alfredi)的共生菌,尤其是刺盘石黄衣共生菌的分离培养物进行了首次研究。对于上述三种地衣体及其共生菌的化学物质进行了比较分析。研究与分析结果表明,三种石黄衣地衣体化学物质,即蒽醌类化合物完全一致。此外, Lindblom从15种北美石黄衣地衣体中检测出了彼此一致的5种蒽醌类化合物。因此,该作者认为石黄衣属的蒽醌类化合物不具有种级分类学意义。本文的实验结果也证实了这一观点。但是,本文对于通过子囊孢子释放法获得的中国三种石黄衣共生菌的化学物质进行了检测和分析,其结果呈现出比较丰富的多样性。其中刺盘石黄衣共生菌化学物质与丽石黄衣和中国石黄衣共生菌所含的化学物质存在明显差异。因而,刺盘石黄衣共生菌化学物质在该种地衣的鉴定中具有重要的参考价值。 此外,文章亦检测和分析了丽石黄衣的10株共生菌化学物质。供试菌株均在相同培养条件和培养时间下获得。其化学物质的TLC图谱,除Nos. 5, 7, 及10稍有差异外,几乎完全一致。由此看来,它们稳定性也是比较明显的。 上述结果提示我们,在地衣系统生物学研究中,除了对于地衣体化学物质进行常规检测与分析之外,对于分离培养的各种地衣共生真菌化学物质的检测与分     

托木尔峰国家级自然保护区岩生地衣群落生态位研究

为了查明托木尔峰国家级自然保护区岩面生地衣对资源的利用和环境梯度分布规律, 采用样方法进行不同资源位群落调查, 利用生态位宽度、生态位相似性和生态位重叠指数测试了12 个岩面生地衣优势种群的生态位。结果表明, 丽石黄衣(B_i=0.6057; B_a=0.5804)、包氏微孢衣(B_i=0.5488;B_a=0.5374)、硬袋衣(B_i=0.4825;B_a=0.3825)、双缘衣(B_i=0.4615;B_a=0.3756)、皮果衣(B_i=0.4302;B_a=0.2682)等5 个种群的Shannon-Wiener 和Levins 生态位宽度最大, 广泛的分布在托木尔峰国家级自然保护区不同海拔的各个样点, 地衣种群的生态位相似性随着生态位宽度的增加而上升。从生态位重叠指数可知, 优势种群间生态位重叠现象较普遍, 但重叠值较低。说明在托木尔峰国家级然保护区岩面生地衣优势种群间因利用相同资源而产生的种间竞争较低, 群落稳定性较高。     

五种石黄衣中次生代谢产物的高压液相色谱分析*

对于五种石黄衣Xanthoria中的次生代谢产物进行了高压液相色谱(HPLC)分析。它们是刺盘石黄衣Xanthoria alfredi、拟石黄衣X. fallax、丽石黄衣X. elegans、粉芽石黄衣X. sorediata和中国石黄衣X. mandschurica。分析结果表明,按照石黄酮(parietin)对拟石黄醛(fallacinal)与黄枝醇(teloschistin)在石黄衣中的相对含量百分比之商将五种石黄衣划分为E组 (Q>14) 和F组 (Q<1.20)。 其中丽石黄衣和粉芽石黄衣属于E组,裂片通常较狭窄,无假根;刺盘石黄衣和拟石黄衣属于F组,裂片通常较宽,具有假根。中国石黄衣中既有E组个体,又有F组个体。对于中国石黄衣的特殊现象仍需要进一步研究。此外,一份拟石黄衣标本的HPLC图谱亦显示了种内化学多样性。     

新疆托木尔峰国家级自然保护区岩面生地衣群落数量分类及其与环境相关性

采用样地法对新疆托木尔峰国家级自然保护区岩面生地衣群落的种类组成进行调查和统计,并以各种类的盖度为指标、应用双向指示种分析( TWINSPAN)和除趋势对应分析( DCA)对岩面生地衣群落进行数量分类;采用S?rensen相似性系数分析各群丛的物种相似性;此外,应用典范对应分析( CCA)探讨了岩面生地衣种类分布与环境因子间的关系。结果表明：该保护区岩面生地衣群落共包含58种地衣,隶属于6目18科35属;优势科有5个,包含的属、种数量分别占该保护区岩面生地衣属、种总数的42.86%和62.07%。依据TWINSPAN和DCA分析结果并结合生境特征,可将该保护区岩面生地衣群落划分为5个群丛：群丛 A,包氏微孢衣+双缘衣群丛( Assoc. Acarospora bohlinii+Diploschistes scruposus);群丛 B,油黄茶渍+亚白平茶渍+柔扁枝衣群丛( Assoc. Candelariella oleifera+Aspicilia subalbicans+Evernia divaricata);群丛C ,斑纹网衣+旱梅衣+淡肤根石耳群丛( Assoc. Lecidea tessellata+Parmelia vegans+Umbilicaria verginis);群丛D,丽石黄衣+白泡鳞衣群丛( Assoc. Xanthoria elegans+Toninia candida);群丛E,皮果衣+硬袋衣群丛( Assoc. Dermatocarpon miniatum+Hypogymnia austerodes)。相似性分析结果表明：群丛A与群丛B、群丛C与群丛D间的物种相似性较高,相似性系数分别为0.615和0.733;群丛B与群丛C间的物种相似性次之,相似性系数为0.363;其他群丛间的物种相似性均较低。 CCA分析结果显示：该保护区岩面生地衣群落的物种分布受到海拔、光照强度、岩面pH值和相对湿度的影响。     

中国新疆博格达山周边地区大型地衣物种多样性及分布特征

本研究对中国新疆博格达山周边地区大型地衣进行地衣分类学和生态学结合的综合研究,通过分析大型地衣物种多样性和分布特征,探讨影响地衣分布的环境变量与生态因子。研究结果表明:(1)分布在博格达山周边地区的大型地衣共有43种,隶属于6目、11科、15属,其中茶渍目和黄枝衣目大型地衣占优势,分别占该地区大型地衣科、属、种总数的55%、67%、81%。(2)博格达山周边地区的大型地衣组成5个样点组,分别是蓝灰蜈蚣衣+裂片石黄衣组、细片石黄衣+亚灰大孢蜈蚣衣组、长缘毛蜈蚣衣+菊叶黄梅组、地卷+暗裂芽黑蜈蚣衣组、黑蜈蚣衣+枪石蕊组,样点组的分布与环境因子密切相关。(3)在影响大型地衣分布的环境因素中海拔对地衣种类分布的影响较显著。本研究为更准确地确定博格达山区大型地衣分布规律提供科学依据。     

新疆博格达山岩面生地衣群落结构特征

根据对新疆博格达山岩面生地衣群落20个样点(20m×20m)调查的数据,以各地衣种的盖度为指标结合双向指示种分析方法(TWINSPAN)和除趋势对应分析法(DCA)对博格达山岩面生地衣群落进行数量分类并分析了群落结构特征及其多样性和相似性。采用典范对应分析法(CCA)对各群落的物种分布格局与环境因子的关系进行研究。结果表明,TWINSPAN分析和DCA排序将分布在博格达山的37种岩面生地衣分为以下5个群丛。群丛1:斑纹网衣(Lecidea tessellate Florke)+粉芽盾衣(Peltula euploca(Ach.)Poelt)+杜瑞氏黄梅(Xanthoparmelia durietzii Hale)群丛,有25个种,总覆盖度为30.145%,多样性为4.025;群丛2:袋衣(Hypogymnia physodes(L.)Nyl.)+白边平茶渍(Aspicilia sublaqueata(H.Magn.)J.C.Wei)+砖孢胶衣(Collema subconveniens Nyl.)群丛,有17个种,地衣总盖度为15.885%,多样性为3.196;群丛3:聚茶渍(Lecanora accumulate H.Magn.)+丽石黄衣(Xanthoria elegans(Link)Th.Fr.)+亚洲平茶渍(Aspicilia asiatica(H.Magn.)Yoshim.)群丛,有30个种,地衣总盖度为37.87%,多样性为4.357;群丛4:中华石果衣(Endocarpon sinense H.Magn.)+伴藓大孢蜈蚣衣(Physconia muscigena(Ach.)Poelt.)+垫脐鳞衣(Rhizoplaca melanophthalma(DC.)LeuckertPoelt)群丛,有24个种,地衣总盖度为30.458%,多样性为3.912;群丛5:石胶衣(Collema flaccidum(Ach.)Ach.)+短绒皮果衣(Dermatocarpon vellereum Zschacke)+绿黑地图衣(Rhizocarpon viridiatrum(Wulfen)Korber.)群丛,有18个种,地衣总盖度为19.331%,多样性为3.515。CCA排序结果反映,该地区岩面生地衣的分布与海拔高度、光照强度、岩石pH和人为干扰有关,其中影响最大的因素是海拔高度,其次为光照强度和干扰。坡向和岩石大小对地衣种类分布的影响不显著。     

The significance of precipitation and substrate chemistry for epiphytic lichen diversity in spruce-fir forests of the Salish Mountains, northwestern Montana

The relevance of chemical site factors for the abundance of epiphytic lichens was studied in Picea engelmannii-Abies lasiocarpa forests of the Salish Mountains, northwestern Montana, USA. The Salish Mountains are an area with relatively low atmospheric pollutant load and low precipitation. Canonical correspondence analysis (CCA) suggests that cover of several lichen species was limited by high Mn concentrations of bark or by high ratios of Mn to Ca, Mg and Fe. Mn in the bark is known primarily to derive from the soil. An effect of Mn concentration or Mn/Ca and Mn/Mg ratios was not found on A. lasiocarpa. This suggests that A. lasiocarpa deposits Mn in the bark in a physiologically inactive form as already known from A. balsamea. Precipitation chemistry was apparently less relevant for epiphytic lichen distribution in the Salish Mountains, as no correlations between element concentrations in stemflow and cover values were found and as amounts of stemflow were small. However, precipitation in the study year was less than average. The lacking significance of precipitation chemistry is probably the cause why epiphytic lichen vegetation differed less between living and dead trees in the Salish Mountains than in highly polluted coniferous forests studied by our group in Germany; in Germany, the difference between living and dead trees was attributed to reduced interception of pollutants from the atmosphere by trees with reduced crown surface. The result of the present study that small-scale variation of epiphytic lichen abundance is only partly explainable by chemical parameters gives rise to the assumption that microclimate (e.g., moisture), which has not been systematically explored, could be an important site factor for epiphytic lichens in the Salish Mountains. Furthermore, tree age was identified by CCA as a relevant site factor for lichens on P. engelmannii.     

Insight into the pattern of heavy-metal accumulation in lichen thalli

BackgroundHeavy metals that pass through the plasmalemma are expected to influence on lichen metabolic processes; however, lichens may tolerate high concentrations of metals by sequestrating them extracellularly. Heavy metal accumulation level fundamentally determine the success of lichens in the colonisation of polluted sites; however, the proportions between extra- and intracellular metal concentrations in lichen thalli are still poorly recognized. In this study metal accumulation patterns of selected toxic trace elements, i.e. Pb, Cd, and micronutrients, i.e. Zn, Cu and Ni, in Cladonia cariosa thalli were recognised in relation to extra- and intracellular fractions.MethodsThe intracellular and total concentrations of Zn, Pb, Cd, Cu and Ni in lichen thalli collected from eleven variously polluted sites were determined by means of atomic absorption spectrometry. Additionally, organic carbon and total nitrogen contents as well as pH of soil substrate were measured.ResultsThe accumulation patterns differed between studied metal elements; the major part of Zn, Pb and Cd loads was accumulated extracellularly, whereas Cu and Ni accumulation was mostly intracellular. Like toxic trace elements, Zn was accumulated mainly extracellularly at high polluted sites. The non-linear models most reliably reflect relationships between intracellular and extracellular metal contents in C. cariosa thalli. The intracellular contents of Zn, Pb, Cd and Cu increased slower at higher than at lower extracellular concentrations. Moreover, at higher total concentrations of elements in the thalli, their extracellular proportions were markedly increased.ConclusionThe results suggest that in the face of extreme Zn-enrichment, lichens demonstrate the ability to accumulate the excess of Zn outside the cells. Therefore, it can be concluded that metal accumulation depend not only on the element but also on its abundance in the environment and direct availability for lichens. The studied species showed a defence against excessive intracellular accumulation when a given element is in excess. Such capability may facilitate the colonization of extremely polluted sites by certain pioneer lichens.     

LICHEN HERBIVORE PREFERENCE: A TEST OF TWO HYPOTHESES

Field data from a saxicolous lichen community in Shenandoah National Park, Virginia, suggested that the slug Pallifera varia grazed more frequently on certain lichen species than would be expected if it fed randomly. Two hypotheses might explain this grazing pattern. The preference hypothesis, that slugs select lichens of highest quality, was tested by measuring the concentration of essential elements in lichens eliciting high and low preference by slugs. Lichens with the highest element contents were assumed to be of the highest quality to herbivores. The avoidance hypothesis, that preference by slugs actually results from the rejection of unpalatable species, was tested by offering slugs choices of baited filter-paper disks impregnated with secondary products of the lichen species in question. Results suggested that preferred lichens had significantly lower concentrations of N, P, and Ca, and that avoided lichens produced secondary products that effectively inhibited Pallifera grazing activity. These results suggested that the avoidance hypothesis was the better explanation for nonrandom Pallifera grazing patterns. Furthermore, they suggested that lichens with the highest concentrations of essential elements are most likely to produce defense compounds, an observation that supports predictions to explain patterns of chemical defense in vascular plants.     

东北大小兴安岭地区梅衣科岛衣类和袋衣类地衣物种多样性

东北大小兴安岭地区是中国地衣的重要分布地之一, 蕴藏着丰富的地衣生物多样性。本研究基于259份标本馆馆藏及采集自东北大小兴安岭31个保护区的新鲜地衣标本, 结合形态学、解剖学、化学和DNA片段的综合分析, 鉴定并报道了该地区梅衣科岛衣类和袋衣类地衣11属31种, 包括环北极成分13种, 东亚成分11种, 世界广布成分3种, 中国特有成分3种, 欧亚成分1种。与之前记录和报道的该地区同类地衣物种组成进行对比, 结果显示隶属于2属的6种地衣在该地区未被重新发现, 表明这些地衣在该地区的分布可能大大萎缩乃至消失, 尤其是属于东亚成分的袋衣属2种: 粉袋衣(Hypogymnia farinacea)和日光山袋衣(H. nikkoensis), 自最初以东北大小兴安岭标本为凭证在中国报道分布后, 30余年未再新增任何标本信息, 日光山袋衣在近期中国大型真菌红色名录评估中被推测处于易危状态。     

To eat or not to eat—relationship of lichen herbivory by snails with secondary compounds and field frequency of lichens

Aims The biochemical defense of lichens against herbivores and its relationship to lichen frequency are poorly understood. Therefore, we tested whether chemical compounds in lichens act as feeding defense or rather as stimulus for snail herbivory among lichens and whether experimental feeding by snails is related to lichen frequency in the field.Methods In a no-choice feeding experiment, we fed 24 lichen species to snails of two taxa from the Clausilidae and Enidae families and compared untreated lichens and lichens with compounds removed by acetone rinsing. Then, we related experimental lichen consumption with the frequency of lichen species among 158 forest plots in the field (Schw?bische Alb, Germany), where we had also sampled snail and lichen species.Important findings In five lichen species, snails preferred treated samples over untreated controls, indicating chemical feeding defense, and vice versa in two species, indicating chemical feeding stimulus. Interestingly, compared with less frequent lichen species, snails consumed more of untreated and less of treated samples of more frequent lichen species. Removing one outlier species resulted in the loss of a significant positive relationship when untreated samples were analyzed separately. However, the interaction between treatment and lichen frequency remained significant when excluding single species or including snail genus instead of taxa, indicating that our results were robust and that lumping the species to two taxa was justified. Our results imply lichen-feeding snails to prefer frequent lichens and avoid less frequent ones because of secondary compound recognition. This supports the idea that consumers adapt to the most abundant food source.     

Chemical variation within and between individuals of the lichenized ascomycete Tephromela atra

HPLC-analysis was used to determine the concentrations of the lichen compounds alectoronic acid (depsidon), -collatolic acid (depsidon) and atranorin (depsid) in the lichenized ascomycete Tephromela atra (syn. Lecanon atra) (Hudson) Hafeliner from limestone walls on the Baltic island of Öland, Sweden. In 24 individuals of T. atra sampled on a stone wall, the pre-reproductive and reproductive tissue did not differ in the concentrations of alectoronic acid, collatolic acid and atranorin. The concentrations of the three lichen compounds were inter-correlated in the reproductive tissue, but not in the pre-reproductive tissue. Single individuals of T. atra ranged in area covered from 10.1 to 147.4 cm² (mean: 38.5 cm²; N=24); 38.6% of this area was pre-reproductive tissue. However, the concentrations of the three lichen compounds were correlated neither with the total area covered by the lichen nor with the percentage of pre-reproductive tissue. This suggests that the concentrations of the lichen compounds do not change with increasing size (age) of the lichen. Analysis of specimens of T. atra from eight localities revealed a significant variation in lichen compounds (range between localities: alectoronic acid 0.60–3.26 μg/mg lichen dry weight (DW); collatolic acid 2.14–11.59 μg/mg lichen DW; atranorin 0.58–4.16 μg/mg lichen DW). The level of grazing observed in the lichens differed significantly among localities. However, no correlations between the concentrations of the three lichen compounds and the grazing damage to the lichens were found.     

亚热带山地森林附生地衣的移植生长及其对环境变化的响应

本研究选取云南哀牢山亚热带森林系统6种常见的附生大型地衣进行为期2年的移植实验,分析其在原生林林外、林缘以及林内3种生境下的生物量增长速率和健康率等的差异,并探讨其生长对环境因子变化的响应。结果显示,网肺衣Lobaria retigera和平滑牛皮叶Sticta nylanderiana在林缘处生物量增长最快;而槽枝Sulcaria sulcata、多花松萝Usnea florida、皮革肾岛衣Nephromopsis pallescens、针芽肺衣Lobaria isidiophora 4种地衣则都是在林外光照更强、湿度更低的条件下生长得最好,林内最差。除网肺衣外,所有地衣的健康率均在林外较好,林缘次之,林内最差。非参数相关分析表明,6种地衣的生长速率和光照以及温度呈正相关,与大气湿度呈负相关;温度和光照是影响地衣生长最主要的生境因子。     

Assessment of the uncertainty of trace metal and nitrogen concentrations in mosses due to sampling,sample preparation and chemical analysis based on the French contribution to ICP-Vegetation

Moss bio-monitoring is a convenient tool for establishing specific or large-scale exposure to atmospheric trace metals and nitrogen pollution. However, the uncertainty associated with sampling, sample preparation and chemical analysis of bio-monitors has been poorly documented, with the exception of one study dealing with lichens; thus, the uncertainty associated with moss bio-monitoring has never been assessed. Here, we propose following the Eurachem guidelines to determine the uncertainties associated with the concentrations of elements measured in mosses during the sampling survey across France in 2011. In addition, we assess the analytical method used in four surveys from 1996 to 2011. Uncertainties were expressed as linear functions of the element concentrations, with minimum and maximum slopes of 14 and 61%, corresponding to nitrogen and chromium, and a median of 32%. Although the data reveal that some steps of the protocol should be performed carefully, they also indicate that the protocol was executed properly and is reproducible. The chemical analyses contribute to a small proportion of the uncertainty associated with the protocol, except for the analysis of chromium. The sampling period, and intra-site variability largely contribute to this uncertainty. The moss species did not introduce additional uncertainty. This integrative assessment of measurement uncertainty will help improve the protocol for future surveys. Such studies could be useful for developing a standard operating procedure and could be used to improve comparisons between countries and to identify temporal trends across Europe.     

Biomonitoring Atmospheric Heavy Metals with Lichens: Theory and Application

Recent records of environmental contamination noted a moderate decrease of SO2 pollution, whereas the burden of atmospheric heavy metals is still considerable. The present review refers to the entrapment, uptake, and accumulation of heavy metals by lichen thalli, made apparent by parameters of lichen vitality and stress. The particulate nature of airborne heavy metals is made evident by parameters referring to the entrapment of heavy-metal containing particles by lichen thalli. The mechanism of uptake of heavy metals, investigated by means of controlled experiments, refers to extracellular and intracellular uptake. The rate of absorption and the accumulation of heavy metals is dependent on morphological features of lichen thalli in addition to kind and intensity of emission sources and to nonanthropogenic factors such as climate and topography. The role of lichens as biomonitors is demonstrated by the case of lead. In contrast to data obtained by retrospective studies, using lichens as biomonitors of heavy metal pollution, performed in the 1970s, which indicated an increase of Pb as a result of the massive use of leaded gasoline, the subsequent disuse of this additive led to a decrease detected in later studies. The disparity of emission sources is illustrated by the case of Hg. Mercury is a product of anthropogenic activity in addition to its natural derivation. The dominance of the anthropogenic factors is made obvious by high levels of Hg recorded near chlor alkali plants and other industrial sites. The role of the substrate in the uptake and accumulation of heavy metals was investigated to detect its relative share. Airborne metals were, however, determinant factors in the metal content of lichen thalli. The interaction of contaminants and biomonitors has a definite physiological impact on the vitality of the biomonitors. Physiological processes of disintegration investigated in this context are degradation of cell membranes and chlorophyll, decrease of the quantum yield of photosynthesis, decrease of the photosynthetic rate, increase of stress-ethylene production, and severe ultrastructural change. Lichens exposed to heavy metal pollution exhibit changes of the spectral reflectance response, an increase of malondialdehyde (MDA), a decrease of ATP, and injury to enzymatic activities. A comparative analysis of data referring to the accumulation of airborne elements in lichens and of data referring to alterations in physiological parameters of lichen viability substantiates the validity of assessments of environmental quality.