矿山环境中锑的表生地球化学研究—以贵州半坡锑矿区为例

锑(antimony，Sb)是一种典型的毒害重金属元素。我国作为世界上最主要的锑生产国，有关锑的表生地球化学及锑污染防治研究还很薄弱。贵州省位于我国西南低温成矿域中心，具有高Sb地球化学背景值，是我国重要的锑工业基地，境内分布着大量Sb矿床，锑矿储量居全国第四位。贵州又地处我国西南喀斯特中心区域，岩溶地貌极其发育，生态环境脆弱。由于大规模锑矿资源的开采利用，锑矿区土壤和水体中Sb污染十分突出，并通过水体或食物链对矿区及流域居民健康形成潜在威胁。因此，研究矿山环境中Sb的表生地球化学对于认识Sb污染的环境效应和寻求Sb污染修复方式具有至关重要的意义。 本文以贵州半坡大型锑矿区为研究对象，系统研究了Sb在矿区岩石、固体废弃物、土壤、水体和植物体等表生环境介质中的分布、迁移、富集规律与赋存机制，阐明了矿区Sb的表生地球化学过程规律，评价了矿区围岩、（废）矿石和尾矿砂等样品的产酸潜力，筛选出新的锑潜在超富集植物和超耐受性植物，并获得以下主要认识： （1） 独山半坡锑矿区是典型高锑地质地球化学背景区，不仅矿石中Sb含量很高，而且围岩中Sb含量也远高于上地壳Sb的平均含量。辉锑矿是锑的主要载体和释放源。 （2） 在固体废弃物中，冶炼废渣中Sb含量最高，其次为废石堆和尾砂库。废石中元素特征基本与围岩一致，继承了围岩的元素特征，而尾矿砂由于破碎、浮选过程的改造，其元素含量特征与围岩存在差异。尾砂砂中Sb以中层最富，底层和表层依次降低，与Fe、Al矿物的分布特征相似，这种分布模式主要受氧化还原条件、雨水淋滤、Fe/Al矿物吸附机制等因素控制。尾矿砂中不同相态的锑含量依次为残渣态>碳酸盐结合态>有机物结合态>可交换态>铁锰氧化物结合态，其中生物易利用态Sb的空间分布特征与总Sb分布特征一致。 （3） 所有的（废）矿石样品都具有潜在产酸能力，需要采取必要的措施抑制酸性矿山排水的产生。尾矿砂没有产酸潜力，这与矿石在选冶过程中加入石灰处理和S含量过低等原因有关，这种碱性环境可能有利于锑的表生地球化学活化和迁移。 （4） 研究区土壤受到严重锑污染，土壤中Sb含量高达51~7369 mg/kg，且随深度增加而逐渐降低，底层含量与对照区相近。这种高含量的Sb可能是与锑矿化有关的裸露岩石和土壤的自然风化淋滤过程和采矿、冶炼活动等造成的。研究区土壤中不同相态的Sb含量依次为残渣态>铁/锰氧化物结合态>碳酸盐结合态>有机物/硫化物结合态>可交换态。土壤中Sb的生物有效性很低。土壤中Sb的迁移与As密切相关。 （5） 研究区水体为SO4/HCO3-Ca型，水体中的Sb以溶解态、悬浮态和沉积物形式存在，并通过吸附-解吸附和水流推移方式进行迁移。洪水期和枯水期水体中Sb的扩散迁移机制存在差异，洪水期研究区内水体对岔河下游水体污染危害更大。在枯水期，岔河水体中溶解态Sb含量和沉积物中Sb含量存在显著正相关关系，表明枯水期沉积物和水体界面间达到物质交换平衡。水体的氧化还原条件和pH值控制着水体中Sb的存在形态。沉积物中不同相态Sb含量依次为残渣态>碳酸盐结合态，铁锰氧化物结合态>可交换态，有机物/硫化物结合态。研究区水体中Sb主要受矿区采矿、选冶活动的强烈影响。水体中硫同位素示踪研究发现，岔河下游水体中59%的S来自于矿山硫源的贡献，表明矿山活动严重影响到岔河下游水体水质。 （6） 植物对土壤中Sb的吸收与植物部位和种类有关。大体上地下部分>地上部分，且根>叶片>茎。在农作物中，白菜>甘蓝>辣椒和稻谷。研究发现，土荆芥(Chenopodium ambrosioides Linn.)是新的Sb潜在超富集植物，鬼针草(Bidens pilosa Linn.)、一年蓬(Erigeron annuus (Linn.) Pers.)、佛甲草(Sedum lineare Thun)、凹叶景天(Sedum emarginatum Migo)、灰灰菜(Chenopodium album Linn.)和鼠麹草(Gnaphalium affine D. Don)也能大量富集Sb，并有很强耐受性。 （7） 研究区这种特殊的高Sb地质环境和人为活动的影响，导致表生环境中Sb的高度富集，造成农作物、水体中Sb含量极高，通过食物链和水体严重影响当地居民的身体健康。

Contribution to the knowlegde of Galician xenoflora (NW Iberian Peninsula, Spain).

Information on 12 exotic plants of diverse interest for the Galician flora are presented. All of them were collected in Ribeira council (SW of the A Coruña province). The total includes 8 novelties at a regional level (Aeonium haworthii, Aloe mitriformis, Brugmansia × candida, Nephrolepis cordifolia, Osteospermum ecklonis, Pelargonium capitatum, Sedum mexicanum, Sparaxis tricolor), and 2 provincial novelties. In addition, information on two taxa hardly mentioned in the literature on Galician vascular flora is also included. All the cited specimens are deposited at the SANT Herbarium.

De plantis carpetanis notulae systematicae, I

Se describe una nueva subespecie de Jasione laevis Lam., J. laevis subsp. gredensis RivasMartines & Sancho. Se propone un nuevo tratamiento y una clave para las especies ibéricas del grupo Sedum villosum L. Se aporta la distribución conocida del grupo en la Peninsula.

Tetti verdi: Analisi sperimentale e Modellazione numerica

I tetti verdi rappresentano, sempre più frequentemente, una tecnologia idonea alla mitigazione alle problematiche connesse all’ urbanizzazione, tuttavia la conoscenza delle prestazioni dei GR estensivi in clima sub-Mediterraneo è ancora limitata. La presente ricerca è supportata da 15 mesi di analisi sperimentali su due GR situati presso la Scuola di Ingegneria di Bologna. Inizialmente vengono comparate, tra loro e rispetto a una superficie di riferimento (RR), le prestazioni idrologiche ed energetiche dei due GR, caratterizzati da vegetazione a Sedum (SR) e a erbe native perenni (NR). Entrambi riducono i volumi defluiti e le temperature superficiali. Il NR si dimostra migliore del SR sia in campo idrologico che termico, la fisiologia della vegetazione del NR determina l'apertura diurna degli stomi e conseguentemente una maggiore evapotraspirazione (ET). Successivamente si sono studiate la variazioni giornaliere di umidità nel substrato del SR riscontrando che la loro ampiezza è influenzata dalla temperatura, dall’umidità iniziale e dalla fase vegetativa. Queste sono state simulate mediante un modello idrologico basato sull'equazione di bilancio idrico e su due modelli convenzionali per la stima della ET potenziale combinati con una funzione di estrazione dell’ umidità dal suolo. Sono stati proposti dei coefficienti di correzione, ottenuti per calibrazione, per considerare le differenze tra la coltura di riferimento e le colture nei GR durante le fasi di crescita. Infine, con l’ausilio di un modello implementato in SWMM 5.1. 007 utilizzando il modulo Low Impact Development (LID) durante simulazioni in continuo (12 mesi) si sono valutate le prestazioni in termini di ritenzione dei plot SR e RR. Il modello, calibrato e validato, mostra di essere in grado di riprodurre in modo soddisfacente i volumi defluiti dai due plot. Il modello, a seguito di una dettagliata calibrazione, potrebbe supportare Ingegneri e Amministrazioni nella valutazioni dei vantaggi derivanti dall'utilizzo dei GR.

Mitigazione dell'isola di calore attraverso i tetti verdi: il caso di studio di Via Terracini a Bologna

Con il termine “tetti verdi” si intendono vere e proprie coperture vegetate, che fungono da valida alterativa alle tipologie convenzionali a coppi oppure in guaina impermeabilizzante. Per quanto questi possano essere considerati una soluzione moderna relativa alle diverse Best Management Practices (BMP), in realtà sono stati realizzati e sfruttati fin dall'antichità. Dagli anni Settanta ad oggi hanno preso sempre più piede in Europa e negli altri continenti a causa dei molteplici benefici che li accompagnano a livello ambientale. All'interno di questo studio ci si pone l‟obiettivo di valutarne i vantaggi, principalmente a livello energetico ed idraulico, riscontrati in letteratura, direttamente sul campo, grazie al sito di studio presso la sede di Ingegneria di via Terracini, Bologna. Sulle coperture del LAGIRN (Laboratorio di Geoingegneria e Risorse Naturali), infatti, nell‟estate 2013 sono stati realizzati due tetti verdi (uno a Sedum, che sarà indicato con la sigla GR, e uno con piante autoctone, identificato con la sigla NA). Tramite il confronto tra le temperature registrate grazie a diversi tipi di strumentazione, è stato possibile quantificare i comportamenti delle coperture su scala annuale, non solo l‟una rispetto l‟altra, ma anche in rapporto a una porzione di tetto lasciata a guaina bituminosa (indicato con la sigla RR). Considerando il ruolo della vegetazione come strumento per la mitigazione del fenomeno d‟isola di calore urbana, infine, con l‟ausilio del software CFD denominato ENVI-met si è modellata l‟intera area del Lazzaretto e si sono simulati tre diversi scenari: 1) Lo stato attuale 2) Una situazione ipotetica con tutte coperture a Sedum 3) Una situazione ipotetica con tutte coperture con specie autoctone per la giornata estiva più calda e per un comune giorno di Ottobre, a seguito di una minuziosa calibrazione. Il confronto tra la situazione reale e quelle supposte dimostra la validità dei green roofs nella lotta al riscaldamento delle grandi città.

Pollen and macrofossils profiles and age determination from three cores in Northeastern Kansas, U.S.A.

Two marshes near Muscotah and Arrington, Atchison County, northeastern Kansas, yielded a pollen sequence covering the last 25,000 yrs of vegetation development. The earliest pollen spectra are comparable with surface pollen spectra from southern Saskatchewan and southeastern Manitoba and might indicate a rather open vegetation but with some pine, spruce, and birch as the most important tree species, with local stands of alder and willow. This type of vegetation changed about 23,000 yrs ago to a spruce forest, which prevailed in the region until at least 15,000 yrs ago. Because of a hiatus, the vegetation changes resulting in the spread of a mixed deciduous forest and prairie, which was present in the region from 11,000 to 9,000 yrs ago, remain unknown. Prairie vegetation, with perhaps a few trees along the valleys, covered the region until about 5,000 yrs ago, when a re-expansion of deciduous trees began in the lowlands.

Palynology on sediment profile Tso Kar in Ladakh

Palynological investigation of a 410 cm long core section from Tso Kar (33°10'N, 78°E, 4527 m a.s.l.), an alpine lake situated in the arid Ladakh area of NW India at the limit of the present-day Indian summer monsoon, was performed in order to reconstruct post-glacial regional vegetation and climate dynamics. The area was covered with alpine desert vegetation from ca. 15.2 to 14 kyr BP (1 kyr=1000 cal. years), reflecting dry and cold conditions. High influx values of long-distance transported Pinus sylvestris type pollen suggest prevailing air flow from the west and northwest. The spread of alpine meadow communities and local aquatic vegetation is a weak sign of climate amelioration after ca. 14 kyr BP. Pollen data (e.g. influx values of Pinus roxburghii type and Quercus) suggest that this was due to a strengthening of the summer monsoon and the reduced activity of westerly winds. The further spread of Artemisia and species-rich meadows occurred in response to improved moisture conditions between ca. 12.9 and 12.5 kyr BP. The subsequent change towards drier desert-steppe vegetation likely indicates more frequent westerly disturbances and associated snowfalls, which favoured the persistence of alpine meadows on edaphically moist sites. The spread of Chenopodiaceae-dominated vegetation associated with an extremely weak monsoon occurred at ca. 12.2-11.8 kyr BP during the Younger Dryas interstadial. A major increase in humidity is inferred from the development of Artemisia-dominated steppe and wet alpine meadows with Gentianaceae after the late glacial/early Holocene transition in response to the strengthening of the summer monsoon. Monsoonal influence reached maximum activity in the Tso Kar region between ca. 10.9 and 9.2 kyr BP. The subsequent development of the alpine meadow, steppe and desert-steppe vegetation points to a moderate reduction in the moisture supply, which can be linked to the weaker summer monsoon and the accompanying enhancement of the winter westerly flow from ca. 9.2 to 4.8 kyr BP. The highest water levels of Tso Kar around 8 kyr BP probably reflect combined effect of both monsoonal and westerly influence in the region. An abrupt shift towards aridity in the Tso Kar region occurred after ca. 4.8 kyr BP, as evidenced by an expansion of Chenopodiaceae-dominated desert-steppe. Low pollen influx values registered ca. 2.8-1.3 kyr BP suggest scarce vegetation cover and unfavourable growing conditions likely associated with a further weakening of the Indian Monsoon.

Pollen record and calculated holocene vegetation and climate dynamics from Sihailongwan Maar Lake, NE China

High-resolution palynological analysis on annually laminated sediments of Sihailongwan Maar Lake (SHL) provides new insights into the Holocene vegetation and climate dynamics of NE China. The robust chronology of the presented record is based on varve counting and AMS radiocarbon dates from terrestrial plant macro-remains. In addition to the qualitative interpretation of the pollen data, we provide quantitative reconstructions of vegetation and climate based on the method of biomization and weighted averaging partial least squares regression (WA-PLS) technique, respectively. Power spectra were computed to investigate the frequency domain distribution of proxy signals and potential natural periodicities. Pollen assemblages, pollen-derived biome scores and climate variables as well as the cyclicity pattern indicate that NE China experienced significant changes in temperature and moisture conditions during the Holocene. Within the earliest phase of the Holocene, a large-scale reorganization of vegetation occurred, reflecting the reconstructed shift towards higher temperatures and precipitation values and the initial Holocene strengthening and northward expansion of the East Asian summer monsoon (EASM). Afterwards, summer temperatures remain at a high level, whereas the reconstructed precipitation shows an increasing trend until approximately 4000 cal. yr BP. Since 3500 cal. yr BP, temperature and precipitation values decline, indicating moderate cooling and weakening of the EASM. A distinct periodicity of 550-600 years and evidence of a Mid-Holocene transition from a temperature-triggered to a predominantly moisture-triggered climate regime are derived from the power spectra analysis. The results obtained from SHL are largely consistent with other palaeoenvironmental records from NE China, substantiating the regional nature of the reconstructed vegetation and climate patterns. However, the reconstructed climate changes contrast with the moisture evolution recorded in S China and the mid-latitude (semi-)arid regions of N China. Whereas a clear insolation-related trend of monsoon intensity over the Holocene is lacking from the SHL record, variations in the coupled atmosphere-Pacific Ocean system can largely explain the reconstructed changes in NE China.

Pollen profile and age determination of sediment core Schwanengrabenrinne, Brandenburg, Germany

In der Döberitzer Heide nördlich von Potsdam wurden vegetationsgeschichtliche Untersuchungen durchgeführt. Das Untersuchungsgebiet befindet sich im östlichen Teil der Nauener Platte, die bisher vegetationsgeschichtlich weitgehend unerforscht war. In sechs verschiedenen Mooren wurden acht Bohrungen niedergebracht. Die Bohrkerne wurden stratigraphisch und pollenanalytisch untersucht und für die Radiocarbondatierung beprobt. Die Pollendiagramme ermöglichen die Rekonstruktion der Vegetationsentwicklung der terrestrischen Standorte und der Moore in der Döberitzer Heide in den letzten 14.000 Jahren. Neben einer Revision der Gliederungsprinzipien der spätglazialen Vegetationsentwicklung Brandenburgs und einer vergleichenden Betrachtung der Moorentwicklung in der Döberitzer Heide wurde besonderes Augenmerk auf die Geschichte des Döberitzer Lindenwaldes gerichtet, der einen Sonderfall in der brandenburgischen Vegetation darstellt. Die Untersuchungen boten die Möglichkeit, die Ursachen seiner Entstehung zu klären, Aussagen zu den Perspektiven seiner Entwicklung zu treffen und mögliche Entwicklungspotentiale von Lindenwäldern im Land Brandenburg aufzuzeigen.

Pollen profiles from three former lakes in the Lake Garda area

1. Late glacial and postglacial sediments from three former lakes in the Lake Garda area (Southern Alps) were investigated. 2. The pollen diagram from Bondone (1550 m) shows an older phase rich in NAP. A younger one corresponds with the Younger Dryas time according to two radiocarbon determinations. In the Preboreal no climatic deterioration could be found. 3. At first plants, which are nowadays typical for snow-ground, pioneer and dwarf shrub associations, immigrated into the surroundings of Bondone. In Alleröd times larch and pine appeared as the first trees. At the beginning of the Preboreal dense forest existed in that region. During the Alleröd timber line was at about 1500 m. 4. In the pollen diagrams from Saltarino (194 m) and Fiavè (654 m) an oldest period rich in NAP is followed by two stadial and two interstadial phases. Tree birches and larches immigrated during the oldest interstadial phase. 5. In the case of Saltarino and Fiavè only a preliminary dating could be made. A correlation seems to be possible with diagrams published by Zoller as well as with the diagram of Bondone. Discrepances in dating, which arise then, are discussed. According to the two possibilities of dating the youngest stadial is synchronous either with the so-called Piottino stadial or the Younger Dryas time. Consequently the oldest interstadial phase of Saltarino corresponds either with the Bölling or with a pre-Bölling interstadial. The last possibility seems to be more probable. 6. In the southern part of the Lake Garda area reforestation was preceded by a long shrub phase mainly with Juniperus. At about 650 m there was a period with Pinus mugo and only with a small amount of Juniperus before reforestation. A phase with Betula nana well known from areas north of the Alps could nowhere be found. 7. In the area under study larch appeared as the first tree. Lateron it has been the most important constituent of the forests near timber line. Birch, which plays an important role as a pioneer tree in Denmark - for instance at the transition of the pollen zones III/IV - as well as in Southern Germany during Bölling time, was of less importance at the southern border of the Alps. In that area the spreading of Pinus occurred very early causing dense forests. 8. During the last stadial phase (probably Younger Dryas time) dense forests with Pinus and Larix existed at 650 m. In the lower part of the Lake Garda area, however, both thermophilous trees as Quercus and herbs frequently occurred. This leads to the conclusion that during this time tree growth was limited by dryness in lower altitudes of the border of the Southern Alps. Pinus and Juniperus, however, do not show higher values in this period, a fact which cannot yet be explained. 9. A list of plants, which were found in the sediments, is compiled. Helodium lanatum, Dictamnus albus, Mercurialis cf. ovata, Buxus, Cerinthe cf. minor, Onosma, Anthericum and Asphodelus albus are findings, which are of special interest for the history of the flora of that region.

Pollen and non-pollen palynomorph records of the Holocene part of the composite sediment core TMD from lake Tso Moriri (NW India) and of modern surface samples from the Tso Moriri region

The high-altitude lake Tso Moriri (32°55'46'' N, 78°19'24'' E; 4522 m a.s.l.) is situated at the margin of the ISM and westerly influences in the Trans-Himalayan region of Ladakh. Human settlements are rare and domestic and wild animals are concentrating at the alpine meadows. A set of modern surface samples and fossil pollen from deep-water TMD core was evaluated with a focus on indicator types revealing human impact, grazing activities and lake system development during the last ca. 12 cal ka BP. Furthermore, the non-pollen palynomorph (NPP) record, comprising remains of limnic algae and invertebrates as well as fungal spores and charred plant tissue fragments, were examined in order to attest palaeolimnic phases and human impact, respectively. Changes in the early and middle Holocene limnic environment are mainly influenced by regional climatic conditions and glacier-fed meltwater flow in the catchment area. The NPP record indicates low lake productivity with high influx of freshwater between ca. 11.5 and 4.5 cal ka BP which is in agreement with the regional monsoon dynamics and published climate reconstructions. Geomorphologic observations suggest that during this period of enhanced precipitation the lake had a regular outflow and contributed large amounts of water to the Sutlej River, the lower reaches of which were integral part of the Indus Civilization area. The inferred minimum fresh water input and maximum lake productivity between ca. 4.5-1.8 cal ka BP coincides with the reconstruction of greatest aridity and glaciation in the Korzong valley resulting in significantly reduced or even ceased outflow. We suggest that lowered lake levels and river discharge on a larger regional scale may have caused irrigation problems and harvest losses in the Indus valley and lowlands occupied by sedentary agricultural communities. This scenario, in turn, supports the theory that, Mature Harappan urbanism (ca. 4.5-3.9 cal ka BP) emerged in order to facilitate storage, protection, administration, and redistribution of crop yields and secondly, the eventual collapse of the Harappan Culture (ca. 3.5-3 cal ka BP) was promoted by prolonged aridity. There is no clear evidence for human impact around Tso Moriri prior to ca. 3.7 cal ka BP, with a more distinct record since ca. 2.7 cal ka BP. This suggests that the sedimentary record from Tso Moriri primarily archives the regional climate history.

Age determination and pollen profile of sediment core Voulkaria 1966, Greece

Lake Voulkaria is situated in northwestern Greece in the Prefecture of Etoloakarnania, 6 km SW of the city of Vonitsa and 10 km east of the northern tip of the island of Levkás (Leukás, Lefkada). The lake is separated from the Ionian Sea on the West by a narrow limestone ridge ca 10 m high and has a size of 940 ha. An almost continuous fringe of Phragmites surrounds the open water. This reed bank is up to 500 m wide along the southern shore of the lake. Water depth is low, predominantly less than 2 m. In the south-eastern part of the lake a maximum depth of 3.1 m was measured in September 1997.