Influence of climatic conditions and industrial emissions on spruce tree-ring Pb isotopes analyzed at ppb concentrations in the Athabasca oil sands region

This study investigates Pb isotope ratios at low concentrations (parts per billion; ppb) in tree rings and soils in the Northern Athabasca Oil Sands Region (NAOSR), western Canada, to evaluate if: (1) climatic conditions influence on tree-ring Pb assimilation; and (2) such low Pb content allows inferring the regional Pb depositional history.Our results reflect the influence of winter snow cover and the importance of minimum temperature and precipitation in spring and summer on the bioavailability of Pb and its passive assimilation by trees in sub-arctic semi-humid climatic conditions. Winter conditions can influence the state of root systems that subsequently impacts the following growth period, while spring and summer conditions likely control microbial processes and water source, and may thus impact Pb assimilation by trees. Thus, the results of tree-ring Pb concentrations show interesting correlation with cumulated snow from November of the previous year to February (ρ = 0.53; P < 0.01; n = 36). Likewise, the ²⁰⁶Pb/²⁰⁷Pb ratios inversely correlate with minimum temperature from April to September (ρ = −0.67; P < 0.01; n = 40) and precipitation from May to August (ρ = −0.42; P < 0.01; n = 36). The isotopic results also suggest that the effects of climatic variations are superimposed by regional industrial Pb deposition: Western North American Aerosols (WNAA) and fugitive dust from the oil sands mining operations appear to be the most likely sources.Importantly, this study suggests that even at low Pb concentrations, tree-ring Pb isotopes are modulated by climatic conditions and potential input of regional and long-range transport of airborne Pb. These interpretations open the possibility of using Pb isotopes as an environmental tool for inferring the pollution history in remote regions, and improving our understanding of its natural cycle through the forest environment.     

Effects of hydrology and river management on the distribution,abundance and persistence of cyanobacterial blooms in the Murray River,Australia

Major cyanobacterial blooms (biovolume > 4 mm³ L⁻¹) occurred in the main water reservoirs on the upper Murray River, Australia during February and March 2010. Cyanobacterial-infested water was released and contaminated rivers downstream. River flow velocities were sufficiently high that in-stream bloom development was unlikely. The location has a temperate climate but experienced drought in 2010, causing river flows that were well below the long-term median values. This coupled with very low bed gradients meant turbulence was insufficient to destroy the cyanobacteria in-stream. Blooms in the upper 500 km of the Murray and Edward Rivers persisted for 5 weeks, but in the mid and lower Murray blooms were confined to a small package of water that moved progressively downstream for another 650 km. Anabaena circinalis was the dominant species present, confirmed by 16S rRNA gene sequencing, but other potentially toxic species were also present in smaller amounts. Saxitoxin (sxtA), microcystin (mcyE) and cylindrospermopsin (aoaA) biosynthesis genes were also detected, although water sample analysis rarely detected these toxins. River water temperature and nutrient concentrations were optimal for bloom survival. The operational design of weirs and retention times within weir pools, as well as tributary inflows to and diversions from the Murray River all influenced the distribution and persistence of the blooms. Similar flow, water quality and river regulation factors were underlying causes of another bloom in these rivers in 2009. Global climate change is likely to promote future blooms in this and other lowland rivers.     

Lead,zinc, cadmium hyperaccumulation and growth stimulation in Arabis paniculata Franch

Metal hyperaccumulation is of great interest in recent years because of its potential application for phytoremediation of heavy metal contaminated soils. In this study, a field survey and a hydroponic experiment were conducted to study the accumulation characteristics of lead (Pb), zinc (Zn) and cadmium (Cd) in Arabis paniculata Franch., which was found in Yunnan Province, China. The field survey showed that the wild population of A. paniculata was hyper-tolerant to extremely high concentrations of Pb, Zn and Cd, and could accumulate in shoots an average level of 2300 mg kg^?1 dry weight (DW) Pb, 20,800 mg kg^?1 Zn and 434 mg kg^?1 Cd, with their translocation factors (TFs) all above one. Under the hydroponic culture, stimulatory effects of Pb, Zn and Cd on shoot dry biomass were noted from 24 to 193 μM Pb, 9 to 178 μM Cd and all Zn supply levels in nutrient solution, while the effects were not obvious in the roots. Chlorophyll concentrations in Pb, Zn and Cd treatments showed an inverted U-shaped pattern, consistent with the change of plant biomass. Pb, Zn and Cd concentrations in the shoots and roots increased sharply with increasing Pb, Zn and Cd supply levels. They reached > 1000 mg kg^?1 Pb, 10,000 mg kg^?1 Zn and 100 mg kg^?1 Cd DW in the 24 μM Pb, 1223 μM Zn and 9 μM Cd treatment, respectively, in which the plants grew healthy and did not show any symptoms of phytotoxicity. The TFs of Zn were basically higher than one and the amount of Zn taken by shoots ranged from 78.7 to 90.4% of the total Zn. However, the TFs of Pb and Cd were well below one, and 55.0–67.5% of total Pb and 57.8–83.5% of total Cd was accumulated in the shoots. These results indicate that A. paniculata has a strong ability to tolerate and hyperaccumulate Pb, Zn and Cd. Meanwhile, suitable levels of Pb, Zn and Cd could stimulate the biomass production and chlorophyll concentrations of A. paniculata. Thus, it provides a new plant material for understanding the mechanisms of stimulatory effect and co-hyperaccumulation of multiple heavy metals.     

Ichthyotoxicity of four species of gymnodinioid dinoflagellates (Kareniaceae,Dinophyta) and purified karlotoxins to larval sheepshead minnow

Two species of Kareniaceae, Karlodinium veneficum (Swan and Huon River isolates) and Karlodinium conicum, and their respective purified karlotoxins (KmTx), were investigated for ichthyotoxicity on larval sheepshead minnow. Two non-karlotoxin producing species, Karenia mikimotoi and Karlodinium ballantinum were also tested. Algal treatments included live and lysed cells (homogenized and CuSO₄ treated) with fish mortalities observed from lysed Ka. veneficum and Ka. conicum but none observed from K. mikimotoi and Ka. ballantinum. The variance in ichthyotoxicity between live and lysed cells of Ka. veneficum (Swan and Huon River) and Ka. conicum (Southern Ocean) confirm that toxin is cell bound and ichthyotoxicity increases upon lysis. Ichthyotoxic blooms of Ka. veneficum in situ in the Swan River, Western Australia and Chesapeake Bay, Maryland, USA are unrelated to algal cell density as mortality was observed with low densities. In laboratory treatments, no fish mortalities were observed upon exposure to live intact cells of all four species at algal concentrations up to 2.5 × 10⁵ cells/mL in replete nutrient growth conditions. Lysed low density (3 × 10⁴ cells/mL) Ka. veneficum (Swan and Huon River) grown under P-limited nutrients caused quicker fish mortality than those cultured in replete nutrient conditions. Pure toxin isolated from Ka. veneficum (Swan and Huon River) and Ka. conicum (Southern Ocean) were toxic to sheepshead minnow larvae, with the lethal dose lowest for Km^HuonTx 2 (508.2 ng/mL), followed by Km^SwanTx 2-1 (563.2 ng/mL), and Km_conicumTx (762.4 ng/mL).     

New insights into the chemical and isotopic composition of human-body biominerals. I: Cholesterol gallstones from England and Greece

We have analyzed gallstones from four patients of Europe and particularly from England (including samples from a mother and a daughter) and Greece. According to the XRD, FTIR, NMR and laser micro-Raman results the studied materials correspond to typical cholesterol monohydrate (ChM). The micro-morphology of cholesterol microcrystals was investigated by means of SEM–EDS. The XRF results revealed that Ca is the dominant non-organic metal in all gallstones (up to ～1.95 wt.%) together with Fe, Cu, Pb and Ni (up to ～19 ppm for each metal). Gallstones from England contain additional Mn (up to ～87 ppm) and Zn (up to ～6 ppm) while the sample of the mother contains negligible Zn and Mn, compared to that of her daughter, but significant As (～4.5 ppm). All cholesterol gallstones examined are well enriched in potentially toxic metals (Pb, as well as Ni in one case) and metalloids (As also in one case) as compared to the global average. The position of Zn, which is a characteristic biometal, in the structure of cholesterol, was investigated by molecular simulation using the Accelrys Materials Studio^® software. On the basis of IRMS results, all gallstones examined exhibit a very light δ¹³C signature (average δ¹³C ～?24‰ PDB). Gamma-ray spectrometry measurements indicate the presence of ²¹⁴Pb and ²¹⁴Bi natural radionuclides due to the ²³⁸U series as well as an additional amount of ⁴⁰K.     

A standardised approach to calculating floodplain tree condition to support environmental watering decisions

Ground-based visual assessment of crown condition is a cornerstone of tree condition assessment globally, and numerous condition assessment approaches have evolved to address the needs and perspectives of different users. In Australia’s iconic Murray–Darling Basin (MDB), stands of floodplain eucalypts are increasingly vulnerable to a range of interacting stressors related to climate change and over-extraction of water for consumptive and agricultural use. A standardised approach developed in 2008 for assessing floodplain trees within the MDB provides extensive guidance to ensure field data is collected consistently. However, there is minimal instruction on how to interpret data, and consequently a range of evaluation approaches have evolved. The lack of a standardised reporting framework generated by these different approaches makes it difficult for floodplain managers and environmental water holders to make repeatable, robust decisions for prioritising water allocations across competing locations. To provide improved lines of evidence to support decision making, this paper describes a ‘best-practise’ approach to calculating a tree condition score from field data. Within, we document existing approaches in the southern Murray–Darling Basin, and recommend a method that meets the needs of floodplain managers as a pragmatic reporting, communication and decision support tool that does not require statistical analysis. Case studies and a revised conceptual model of tree decline and recovery are provided to demonstrate the validity of the recommended approach.

     

Stress responses and specific metal exclusion on mine soils based on germination and growth studies by Australian golden wattle

We reported the Australian golden wattle as a copper stabilizer in abandoned copper mine soils earlier. Here we investigate to confirm this plant’s suitability to grow on metal contaminated mine soils based on stress indication. The seeds of Acacia pycnantha collected from mining area were germinated after heat and no heat treatment on two types of irrigation. The daily irrigated and heat treated seeds gave up to 85% germination on sandy soil. The A. pycnantha was grown under greenhouse condition in six different soils collected from abandoned copper mine at Kapunda in South Australia. Among the six soil samples, soil-1 with the highest copper concentration produced 2.05 mmol g⁻¹ tissue of proline. Proline expression was prominent in more saline soils (1, 5 and 6) having electrical conductivity (EC) 1184, 1364 and 1256 μS, respectively. Chlorophyll a, b and carotenoid levels in plants showed a gradually decreasing trend in all the soils as experiment progressed. The plants grown on soil sample-1, containing 4083 ± 103 mg kg⁻¹ of copper resulted in 18 ± 2 mg kg⁻¹ accumulation in its leaf. The calcium accumulation was significant up to 11648 ± 1209 mg kg⁻¹ in leaf. Although pore water samples showed higher Cu concentration in soils, an increased mobility of arsenic and lead was observed in all the soil samples. Our experiment points out the need for proper monitoring of revegetation processes to avoid revegetation and reclamation failure.     

Surface-water cooling and salinity decrease during the Middle Miocene climate transition at Southern Ocean ODP Site 747 (Kerguelen Plateau)

Paleoceanographic variability at southern high latitude Ocean Drilling Program (ODP) Site 747 was investigated in this study through the interval which spans the Middle Miocene Climate Transition (MMCT). Between 15.0 and 12.2 million years ago (Ma), foraminiferal δ¹⁸O records derived from both benthic (Cibicidoides spp.) and planktonic taxa (Globorotalia praescitula and Globigerina bulloides) reveal a history of changes in water column thermal and salinity structure and a strong imprint of seasonality. Prior to the MMCT, in the interval between 14.35 and 13.9 Ma, G. bulloides displays relatively high δ¹⁸O values similar to those of G. praescitula, interpreted to indicate weakening of the thermocline and/or increased seasonality with cooler early-spring and/or late-fall temperatures. Following this interval, G. bulloides δ¹⁸O values diverge significantly from benthic and G. praescitula values, with G. bulloides values remaining relatively low for at least 600 kyr following the benthic foraminiferal δ¹⁸O shift during the MMCT at ~ 13.9 Ma. This divergence in δ¹⁸O records occurs in direct association with the Mi3 cooling and glaciation event and may suggest: (1) a strengthening of the vertical temperature gradient, with greater cooling of deep waters than surface waters, (2) changes in the depth habitat of G. bulloides, (3) changes in the dominant season of G. bulloides calcification, (4) modification of surface-water δ¹⁸O values in association with enhanced sea-ice formation, (5) increased surface-water carbonate ion concentration, and/or (6) a significant decrease in surface-water salinity across the MMCT. The first of these possible scenarios is not likely, particularly in light of recent Mg/Ca evidence for significant surface-water cooling in the Southern Ocean associated with the MMCT. Of the remaining possibilities, we favor a change in surface salinity to explain the observed trends in δ¹⁸O values and hypothesize that surface salinity may have decreased by up to 2 salinity units at ~ 13.9 Ma. In this scenario, the development of a lower-salinity Antarctic surface layer coincided with regional cooling of both surface and deep waters of the Southern Ocean during the Mi3 glaciation of East Antarctica, and contributed into the dominance of Neogloboquadrina spp. between 13.8 and 13.2 Ma. Additionally, the distinct patterns observed in planktonic foraminiferal δ¹⁸O records spanning the MMCT correspond with changes in the vertical δ¹³C gradient between planktonic and benthic foraminiferal records and major changes in planktonic foraminiferal assemblages at Site 747, providing further evidence of the environmental significance of this climatic transition.     

Description of Massilia rubra sp. nov., Massilia aquatica sp. nov., Massilia mucilaginosa sp. nov., Massilia frigida sp. nov., and one Massilia genomospecies isolated from Antarctic streams,lakes and regoliths

Bacteria of the genus Massilia often colonize extreme ecosystems, however, a detailed study of the massilias from the Antarctic environment has not yet been performed. Here, sixty-four Gram-stain-negative, aerobic, motile rods isolated from different environmental samples on James Ross Island (Antarctica) were subjected to a polyphasic taxonomic study. The psychrophilic isolates exhibited slowly growing, moderately slimy colonies revealing bold pink-red pigmentation on R2A agar. The set of strains exhibited the highest 16S rRNA gene sequence similarities (99.5–99.9%) to Massilia violaceinigra B2^T and Massilia atriviolacea SOD^T and formed several phylogenetic groups based on the analysis of gyrB and lepA genes. Phenotypic characteristics allowed four of them to be distinguished from each other and from their closest relatives. Compared to the nearest phylogenetic neighbours the set of six genome-sequenced representatives exhibited considerable phylogenetic distance at the whole-genome level. Bioinformatic analysis of the genomic sequences revealed a high number of putative genes involved in oxidative stress response, heavy-metal resistance, bacteriocin production, the presence of putative genes involved in nitrogen metabolism and auxin biosynthesis. The identification of putative genes encoding aromatic dioxygenases suggests the biotechnology potential of the strains. Based on these results four novel species and one genomospecies of the genus Massilia are described and named Massilia rubra sp. nov. (P3094^T = CCM 8692^T = LMG 31213^T), Massilia aquatica sp. nov. (P3165^T = CCM 8693^T = LMG 31211^T), Massilia mucilaginosa sp. nov. (P5902^T = CCM 8733^T = LMG 31210^T), and Massilia frigida sp. nov. (P5534^T = CCM 8695^T = LMG 31212^T).     

Population genetic structure and conservation implications of Ceriops decandra in Malay Peninsula and North Australia

Comprehensive information of mangrove genetic resources is requisite for developing strategies for their effective conservation and sustainable use. Genetic diversity within and among populations of a widespread viviparous mangrove Ceriops decandra was determined using inter-simple sequence repeat (ISSR). Ten natural populations were collected from Malay Peninsula and North Australia. At the species level, high genetic variation was detected (P = 72%, H_E = 0.253, and I = 0.379). The estimate of G_ST was 0.882, indicating a high level of genetic differentiation among populations. When populations were grouped according to geographic regions, i.e., East Malaya, West Malaya, Southmost Malaya, and North Australia, AMOVA suggested that most of the total variation (87%) was accounted for by differentiation between regions, with only 4% accounting for variation among populations within regions, and a further 9% partitioned among individuals within a population. A UPGMA dendrogram based on genetic distance revealed a deep split between populations from the eastern Indian Ocean and all others from the western Pacific Ocean, which may result from the historical lowering of sea level at these regions during the recent Pleistocene glaciations. An understanding of the genetic structure of C. decandra provides insight for the conservation and management of this species.     

Mapping riparian condition indicators in a sub-tropical savanna environment from discrete return LiDAR data using object-based image analysis

Mapping, monitoring and managing the environmental condition of riparian zones are major focus areas for local and state governments in Australia. New remotely sensed data techniques that can provide the required mapping accuracies, complete spatial coverage and processing and mapping transferability are currently being developed for use over large spatial extents. The research objective was to develop and apply an approach for mapping riparian condition indicators using object-based image analysis of airborne Light Detection and Ranging (LiDAR) data. The indicators assessed were: streambed width; riparian zone width; plant projective cover (PPC); longitudinal continuity; coverage of large trees; vegetation overhang; and stream bank stability. LiDAR data were captured on 15 July 2007 for two 5 km stretches along Mimosa Creek in Central Queensland, Australia. Field measurements of riparian vegetation structural and landform parameters were obtained between 28 May and 5 June 2007. Object-based approaches were developed for mapping each riparian condition indicator from the LiDAR data. The validation and empirical modelling results showed that the object-based approach could be used to accurately map the riparian condition indicators (R² = 0.99 for streambed width, R² = 0.82 for riparian zone width, R² = 0.89 for PPC, R² = 0.40 for bank stability). These research findings will be used in a 26,000 km mapping project assessing riparian vegetation and physical form indicators from LiDAR data in Victoria, Australia.     

From water to edible fish. Transfer of metals and metalloids in the San Roque Reservoir (Córdoba,Argentina). Implications associated with fish consumption

The concentration of Mn, Fe, Zn, Cu, Cd, Cr, Ni, Ag, Mo, Nd, Al, Ce, As, Sr, Pb, Pt and Hg was analysed in water, sediments, and aquatic organisms from the San Roque Reservoir (Córdoba-Argentina), sampled during the wet and dry season, to evaluate their transfer through the food web. Stable nitrogen (δ¹⁵N) isotopes were used to investigate trophic interactions. According to this, samples were divided into three trophic groups: plankton, shrimp (Palaemonetes argentinus) and fish (Silverside, Odontesthes bonariensis). Liver and gills are the main heavy metal storage tissues in fish. Hg and As concentrations in the muscle of O. bonariensis exceed the Oral Reference doses for metals established by USEPA (2009). Trophic magnification factors (TMFs) for each element were determined from the slope of the regression between trace element concentrations and δ¹⁵N. Calculated TMFs showed fundamental differences in the trophodynamics of the studied elements during the wet and dry season in the San Roque Reservoir. Concentrations of Ni, Cd, Cr, Al, Mn, Fe, Mo, Ce, Nd, Pt and Pb during both seasons, and Sr during the dry season, showed statistically significant decreases (TMF < 1) with increasing trophic levels. Thus these elements were trophically diluted in the San Roque food chain. Conversely, Cu, Ag and As (dry season) showed no significant relationships with trophic levels. Among the elements studied, Hg in the wet season, and Zn in the dry season were the only ones showing a statistically significant increase (TMF > 1) in concentration with trophic level. Current results trigger the need for further studies to establish differential behaviour with different species within the aquatic web, particularly when evaluating the transfer of toxic elements to edible organisms, which could pose health risks to humans.     

Constraints on Miocene oceanography and climate in the Western and Central Paratethys: O-, Sr-, and Nd-isotope compositions of marine fish and mammal remains

The Paratethys evolved as a marginal sea during the Alpine–Himalayan orogeny in the Oligo-Miocene. Sediments from the northern Alpine Molasse Basin, the Vienna, and the Pannonian Basins located in the western and central part of the Paratethys thus provide unique information on regional changes in climate and oceanography during a period of active Alpine uplift. Oxygen isotope compositions of well-preserved phosphatic fossils recovered from the sediments support deposition under sub-tropical to warm-temperate climate with water temperatures of 14 to 28 °C for the Miocene. δ¹⁸O values of fossil shark teeth are similar to those reported for other Miocene marine sections and, using the best available estimates of their biostratigraphic age, show a variation until the end of the Badenian similar to that reported for composite global record. The ⁸⁷Sr/⁸⁶Sr isotope ratios of the fossils follow the global Miocene seawater trend, albeit with a much larger scatter. The deviations of ⁸⁷Sr/⁸⁶Sr in the samples from the well-constrained seawater curve are interpreted as due to local input of terrestrially-derived Sr. Contribution of local sources is also reflected in the ε_Nd values, consistent with input from ancient crystalline rocks (e.g., Bohemian Massif) and/or Mesozoic sediments with ε_Nd < ? 9. On the other hand, there is evidence for input from areas with Neogene volcanism as suggested by samples with elevated ε_Nd values > ? 7. Excluding samples showing local influence on the water column, an average ε_Nd value of ? 7.9 ± 0.5 may be inferred for the Miocene Paratethys. This value is indistinguishable from the ε_Nd value of the contemporaneous Indian Ocean, supporting a dominant role of this ocean in the Western and Central Paratethys.     

A 1700-year Athrotaxis selaginoides tree-ring width chronology from southeastern Australia

Few Southern Hemisphere tree-ring chronologies exceed 1000 years in length. We present a ca. 1700 years of indexed values for the long-lived conifer Athrotaxis selaginoides at Cradle Mt in southeastern Australia and compare it with the only other published millennial-plus length tree-ring chronology for Australia: the nearby Mt Read Lagarostrobos franklinii. We use simple correlation function and pointer year analyses to compare the climate responses of the two species (temperature, precipitation and growing degree days). Both chronologies show accelerated growth at their modern ends, but this growth acceleration is not synchronous, beginning approximately a quarter of a century earlier at the Cradle Mt site. This discrepancy may highlight the relevance of chronology composition and/or physiological differences in the species. Although the seasonality of the climatic responses of the two species is similar, that of A. selaginoides is generally weaker than that of L. franklinii. Somewhat paradoxically, the only pointer years in common between the chronologies are 1898 and 1908 CE. The periods from 600 to 900 CE and ∼1200–1450 CE are conspicuous for their absence of positive pointer years while no negative pointer years occur for either site from ∼1200–1350 CE. It is possible that differing patterns of pointer years can be partially explained by a peak in establishment from ∼1150–1850 CE at the Mt Read L. franklinii site compared to continuous establishment at Cradle Mt. Although statistically significant and time-stable climate responses for the A. selaginoides chronology are too weak to base a single-chronology climate reconstruction on, the long chronology will likely make an important contribution to future multi-proxy temperature reconstructions for southeastern Australia.     

Neutralization and neoformation: Analogous processes in the atmosphere and in lichen thalli—A review

The present review discusses the concept of mineral neoformation which describes the formation of gypsum as the end-product of analogous processes occurring in the atmosphere, in the lichen thallus and on lithic substrates colonized by lichens. The formation of gypsum occurs as a result of H₂SO₄ reacting with CaCO₃. Climate change, e.g. global warming and desertification led to an increasing number of annual dust storms originating in North African deserts, from 5 days in 1958 to 30 days in 2006, i.e. sixfold in 48 years. Calcium is a major constituent of desert dust. The enlarged dust load in the Eastern Mediterranean coincides with the amount of calcium accumulated in lichens: from 6300 μg g⁻¹ in 1978 to 36,603 ± 7563 μg g⁻¹ in 2002, i.e. about sixfold in 24 years. Desert dust carrying Ca-containing particles reacts with sulfuric acid produced in the atmosphere following both volcanic and anthropogenic activities. Gypsum produced via neoformation in the atmosphere, precipitates in varying formations, e.g. iberulites. A process of neutralization leads to the formation of biominerals. CaCO₃-containing particles entrapped in the lichen thallus react with sulfuric acid to produce gypsum as its end-product, detected in the form of crystals on the outer surface of the thallus. The formation of biogenic gypsum occurs also via the reaction of intra- and extracellular Ca²⁺ cations with SO₄²⁻ anions, penetrating into, or found inside thallial cells. The catalytic capability of lichens is evident in the process of neoformation of gypsum on lithic substrates, e.g. granite.     

Holocene environmental changes as recorded by mineral magnetism of sediments from Anguli-nuur Lake,southeastern Inner Mongolia Plateau,China

Two cores, one 1141-cm long (An-S) and the other 885-cm long (An-A), were retrieved from Anguli-nuur Lake (41°18′–24′N, 114°20′–27′E, ～ 1315 masl), one of the largest lakes in the transition zone between a semi-humid and semi-arid climate parallel to the present limit of the southeast monsoon along the southeastern Inner Mongolia Plateau in north China. Mineral-magnetic parameters (χ_lf, ARM, IRM_300mT, SIRM and IRM_? 300mT) were measured on An-S and two additional parameters (χ_ARM and HIRM) and four inter-parametric ratios (χ_ARM/SIRM, IRM_300mT/SIRM, IRM_? 300mT/SIRM and SIRM/χ_lf) were calculated. Potential sources of these lake sediments (catchment soils and dune materials close to the lake and in a distant sand plain) were sampled, and the magnetic properties of the surface-material specimens were measured. A chronological model was developed for An-S by comparing and combining AMS¹⁴C dates of An-S with ¹³⁷Cs, ²¹⁰Pb and AMS¹⁴C dates of An-A. With the help of surface-material magnetism, the magnetic data of An-S in combination with particle size, TOC and C/N and pollen analyses indicate the environmental changes during the last ～ 10,000 years around this lake. Conditions began to ameliorate at 10,900 cal. yr BP (9600 ¹⁴C yr BP) and thus relatively wet and warm environments prevailed during 10,900–8900 cal. yr BP (9600–8000 ¹⁴C yr BP). The Holocene optimum or the wettest and warmest conditions, was during 8900–7400 cal. yr BP (8000–6500 ¹⁴C yr BP). The environment began to deteriorate from 7400 cal. yr BP (6500 ¹⁴C yr BP) and the driest and coolest conditions occurred during 2200–480 cal. yr BP. There may have been a minor amelioration after 480 cal. yr BP. The inferred changes in palaeoenvironmental conditions around Anguli-nuur Lake are broadly in agreement with those around most other sites on the Inner Mongolia Plateau.     

δ15N and δ13C diet–tissue discrimination factors for large sharks under semi-controlled conditions

Stable isotopes (δ¹⁵N and δ¹³C) are being widely applied in ecological research but there has been a call for ecologists to determine species- and tissue-specific diet discrimination factors (?¹³C and ?¹⁵N) for their study animals. For large sharks stable isotopes may provide an important tool to elucidate aspects of their ecological roles in marine systems, but laboratory based controlled feeding experiments are impractical. By utilizing commercial aquaria, we estimated ?¹⁵N and ?¹³C of muscle, liver, vertebral cartilage and a number of organs of three large sand tiger (Carcharias taurus) and one large lemon shark (Negaprion brevirostris) under a controlled feeding regime. For all sharks mean ± SD for ?¹⁵N and ?¹³C in lipid extracted muscle using lipid extracted prey data were 2.29‰ ± 0.22 and 0.90‰ ± 0.33, respectively. The use of non-lipid extracted muscle and prey resulted in very similar ?¹⁵N and ?¹³C values but mixing of lipid and non-lipid extracted data produced variable estimates. Values of ?¹⁵N and ?¹³C in lipid extracted liver and prey were 1.50‰ ± 0.54 and 0.22‰ ± 1.18, respectively. Non-lipid extracted diet discrimination factors in liver were highly influenced by lipid content and studies that examine stable isotopes in shark liver, and likely any high lipid tissue, should strive to remove lipid effects through standardising C:N ratios, prior to isotope analysis. Mean vertebral cartilage ?¹⁵N and ?¹³C values were 1.45‰ ± 0.61 and 3.75‰ ± 0.44, respectively. Organ ?¹⁵N and ?¹³C values were more variable among individual sharks but heart tissue was consistently enriched by ~ 1–2.5‰. Minimal variability in muscle and liver δ¹⁵N and δ¹³C sampled at different intervals along the length of individual sharks and between liver lobes suggests that stable isotope values are consistent within tissues of individual animals. To our knowledge, these are the first reported diet–tissue discrimination factors for large sharks under semi-controlled conditions, and are lower than those reported for teleost fish.     

Monsoonal and other climatic influences on radiolarian species abundance over the last 35 ka,as recorded in core FR10/95-GC17, off North West Cape (Western Australia)

Species abundance counts from 46 surface sediment samples have been used to develop transfer functions for the reconstruction of salinity, and dissolved nitrates in the eastern Indian Ocean. Application of the functions to samples from deep-sea core FR10/95-GC17 [22° 07.74′ S, 113° 30.11′ E] shows that, offshore North West Cape, Western Australia, regional changes in salinity and the availability of dissolved nitrates were more significant in determining radiolarian species distributions over the last 35 ka than temperature. In addition, variations in the reconstructed data have been shown to reflect changes in marine currents and terrestrial rainfall over the study period.     

Diversity and heavy metal tolerance of endophytic fungi from six dominant plant species in a Pb–Zn mine wasteland in China

The diversity and metal tolerance of endophytic fungi from six dominant plant species in a Pb–Zn mine wasteland in Yunnan, China were investigated. Four hundred and ninety-five endophytic fungi were isolated from 690 tissue segments. The endophytic fungal colonization extent and isolation extent ranged from 59 % to 75 %, and 0.42–0.93, respectively, and a positive correlation was detected between them. Stems harboured more endophytic fungi than leaves in each plant species, and the average colonization extent of stems was 82 %, being significantly higher than that of leaves (47 %) (P ≤ 0.001, chi-square test). The fungi were identified to 20 taxa in which Phoma, Alternaria and Peyronellaea were the dominant genera and the relative frequencies of them were 39.6 %, 19.0 % and 20.4 %, respectively. Metal tolerance test showed that 3.6 mM Pb²⁺ or 11.5 mM Zn²⁺ exhibited the greatest toxicity to some isolates and they did not grow on the metal-amended media. In contrast, some isolates were growth stimulated in the presence of tested metals. The isolates of Phoma were more sensitive to Zn²⁺ than the isolates of Alternaria and Peyronellaea. However, the sensitivity of isolates to Pb²⁺ was not significantly different among Phoma, Alternaria, Peyronellaea and other taxa (P > 0.05, chi-square test). Our results suggested that fungal endophyte colonization in Pb–Zn polluted plants is moderately abundant and some isolates have a marked adaptation to Pb²⁺ and Zn²⁺ metals, which has a potential application in phytoremediation in this area.     

Genetic differentiation in Pyrenophora teres populations measured with AFLP markers

The genetic structure and occurrence of mating types and forms of Pyrenophora teres, the causal agent of net blotch on barley, was studied among 278 isolates collected from the northern hemisphere and from Australia. Genetic differentiation was high (F_CT 0.238, P = 0.002) between P. teres f. teres (PTT) isolates originating from Northern Europe, North America, Russia and Australia. The P. teres population in Australia was clearly divided into two subgroups (F_CT 0.793, P < 0.001) according to the form identity: PTT and P. teres f. maculata (PTM), with the PTT samples showing a greater degree of differentiation (F_ST 0.573, P < 0.001) among Australian states than the PTM samples (F_CT 0.219, P < 0.001). No differentiation was found among locations within Australian states. Both mating types (MAT1 and MAT2) were equally common (1:1) in several locations in Australia and in Finland. The only exception was Krasnodar, Russia, where only MAT2 was identified. Our results show that the prevalence of sexual reproduction, occurrence of forms of P. teres, and genetic differentiation between geographical regions are highly variable. The paper discusses the various effects and outcomes of population selection in Australia and in the northern barley growing regions.