A versatile pump-sampler for live zooplankton

The sampler consists of a readily interchangeable nylon-mesh sleeve mounted on the suction of a submersible pump. The unit is compact and robust, with the mesh totally protected from external damage. Although designed primarily for use in the intakes and outfalls of power stations, this sampler and the variants described could find more general application. The incorporation of a submersible pump circumvents both the suction lift restriction and the problems associated with plankton travel through long lengths of hose that are inherent in previous designs. Less than 3% of the members of estuarine/inshore zooplankton so collected showed damage or had died within 48 hours of capture.     

Preservation/exhumation of ultrahigh-pressure subduction complexes

Ultrahigh-pressure (UHP) metamorphic terranes reflect subduction of continental crust to depths of 90–140 km in Phanerozoic contractional orogens. Rocks are intensely overprinted by lower pressure mineral assemblages; traces of relict UHP phases are preserved only under kinetically inhibiting circumstances. Most UHP complexes present in the upper crust are thin, imbricate sheets consisting chiefly of felsic units ± serpentinites; dense mafic and peridotitic rocks make up less than  10% of each exhumed subduction complex. Roundtrip prograde–retrograde P–T paths are completed in 10–20 Myr, and rates of ascent to mid-crustal levels approximate descent velocities. Late-stage domical uplifts typify many UHP complexes.

Sialic crust may be deeply subducted, reflecting profound underflow of an oceanic plate prior to collisional suturing. Exhumation involves decompression through the P–T stability fields of lower pressure metamorphic facies. Scattered UHP relics are retained in strong, refractory, watertight host minerals (e.g., zircon, pyroxene, garnet) typified by low rates of intracrystalline diffusion. Isolation of such inclusions from the recrystallizing rock matrix impedes back reaction. Thin-aspect ratio, ductile-deformed nappes are formed in the subduction zone; heat is conducted away from UHP complexes as they rise along the subduction channel. The low aggregate density of continental crust is much less than that of the mantle it displaces during underflow; its rapid ascent to mid-crustal levels is driven by buoyancy. Return to shallow levels does not require removal of the overlying mantle wedge. Late-stage underplating, structural contraction, tectonic aneurysms and/or plate shallowing convey mid-crustal UHP décollements surfaceward in domical uplifts where they are exposed by erosion. Unless these situations are mutually satisfied, UHP complexes are completely transformed to low-pressure assemblages, obliterating all evidence of profound subduction.     

恒载作用下损伤梁的弯矩重分布研究

根据等效刚度原理定义损伤程度,对损伤采用损伤位置、损伤程度和损伤长度三个参数来描述,从材料力学平面弯曲理论出发,运用小变形的平面弯曲挠曲线近似微分方程,并引入损伤程度的定义,推导出恒载作用下两端固定损伤梁弯矩方程的隐含表达式。对恒载作用下两端固定损伤梁进行了各种损伤情况下弯矩重分布的对比分析,总结出了其弯矩重分布规律。本研究的目的是期望为桥梁的健康检测、损伤识别理论研究奠定基础。     

Paleoceanographic Setting and Preservation of Buried Manganese Deposits in DSDP/ODP Cores

Abstract. The occurrence, lithology, and stratigraphic setting of buried manganese deposits and associated host sediments in cores obtained on Legs 123–210 of the Ocean Drilling Program (ODP) are examined in order to establish the formative environment and conditions of preservation. Fossil manganese nodule and crusts are found to have formed or deposited throughout the period from 100 Ma to the present, with an additional example of formation near 137 Ma, suggesting that the deep-sea environment has been oxic and suitable for the formation of manganese nodules and crusts since the Cretaceous. Many manganese nodules and crusts occur on horizons corresponding to hiatuses in sedimentation or periods of slow sedimentation, consistent with the environment in which modern nodules form (sedimentation rate less than 10 m/m.y.). Sediments overlying the fossil nodules and crusts are oozes or biogenic sediments with sedimentation rates of 1–18 m/m.y. Low total organic carbon (<0.1 wt%) in the overlying sediments and high sulfate content (>25 mM) in interstitial water around the manganese horizon suggest that no strong reduction occurred within the overlying sediments. Coverage by biogenic sediments containing only small amounts of organic matter is therefore considered important for the preservation of manganese nodules and crusts. Manganese carbonate occurs sporadically as nodules, concretions or thin layers in various host sediments, including clay, calcareous ooze and siliceous ooze with sedimentation rates of 6–125 m/m.y. Hiatuses are rare around the host sediments of manganese carbonate. Higher total organic carbon (0.2–1.8 wt%) in the host sediments and lower sulfate content (0–25 mM) in interstitial water around the manganese carbonate horizon suggest that reduction in association with decomposition of organic matter would have proceeded in the host sediments.     

西昌盆地五峰组—龙马溪组页岩气保存条件研究

保存条件是影响页岩气富集高产的关键因素。本文综合利用地质、钻井等资料,分析了西昌盆地五峰组-龙马溪组的顶底板条件、构造特征、地层压力特征和气体组分,从宏观和微观两个方面对影响页岩气保存的主要指标进行了研究,在此基础上开展了西昌盆地保存条件综合评价。结果表明：盆地各凹陷主要由走滑-冲断带相隔,凹陷内地层缓倾,构造样式表现为宽缓-开阔褶皱,由于受到盆缘断裂冲断作用的影响,盆缘褶皱常表现为紧闭-闭合褶皱,地层近于直立,局部发生倒转;西昌盆地内部构造缩短量较少,缩短率均<20%,指示整个盆地内部构造变形强度较弱;盆地南部布拖区域,龙马溪组页岩可形成典型压力封存箱式地质结构,箱内与箱外存在一定压力系数差,箱内地层压力稳定,保存条件好;综合多期构造作用下的断裂和裂缝发育状况、隆升剥蚀、构造变形条件等因素,在西昌盆地东缘优选出昭觉和布拖两个页岩气有利区。     

A physical model for the transport and sorting of fine-grained sediment by turbidity currents

Turbidite muds in cores from the outer Scotian continental margin, off eastern Canada, contain abundant thin silt laminae. Graded laminated units are recognized in parts of this sequence. These represent single depositional events, and show a regular decrease in modal grain size and thickness of the silt laminae through the unit. A similar fining trend is shown by both silt and mud layers over hundreds of kilometres downslope. Textural analysis of individual laminae allows the construction of a dynamically consistent physical model for transport and sorting in muddy turbidity currents. Hydraulic sorting aggregates finer material to the top and tail regions of a large turbidity flow which then overspills its channel banks. Downslope lateral sorting occurs with preferential deposition of coarser silt grains and larger mud flocs. Depositional sorting by increased shear in the boundary layer separates clay flocs from silt grains and results in a regular mud/silt lamination. Estimates can be made of the physical parameters of the turbidity flows involved. They are a minimum of several hundreds of metres thick, have low concentrations (of the order of 10^?3 or 2500 mg 1^?1), and move downslope at velocities of 10-20 cm s^?1. A 5 mm thick, coarse silt lamina takes about 10 h to deposit, and the subsequent mud layer ‘blankets’ very rapidly over this. A complete unit is deposited in 2-6 days which is the time it takes for the turbidity flow to pass a particular point. These thick, dilute, low-velocity flows are significantly different from the ‘classical’ turbidity current. However, there is mounting evidence in support of the new concept from laboratory observations and direct field measurements.     

Grain sorting in gravel-bed streams and the choice of particle sizes for flow-competence evaluations

Flow-competence assessments of floods have been based on the largest particle sizes transported, and yield either the mean flow stress, mean velocity, or discharge per unit flow width. The use of extreme particle sizes has potential problems in that they may have been transported by debris flows rather than by the flood, it may be difficult to locate the largest particles within the flood deposits, and there are questions concerning how representative one or a few large particles might be of the transported sediments and therefore of the flood hydraulics. Such problems would be eliminated for the most part if competence evaluations are based on median grain sizes of transported sediments, or perhaps on some coarse percentile that is established by a reasonable number of grains. In order to examine such issues, the gravel-transport data of Milhous from Oak Creek, Oregon, and of Carling from Great Eggleshope Beck, England, have been analysed in terms of changing grain-size percentiles with varying flow stresses. A comparison between these two data sets is of added interest because the bed material in Oak Creek is segregated into well-developed pavement and subpavement layers, while such a layering of bed materials is largely absent in Great Eggleshope Beck. The analyses show that the trend of increasing sizes of the largest particles in the bedload samples (diameter D_m) with increasing flow stresses is consistent with similar dependencies based on sieve percentiles ranging from the medians (D₅₀) to the 95th percentiles (D₉₅). This indicates that the largest particles are an integral part of the overall distributions of bedload grain sizes, and respond to changing flow hydraulics along with the rest of the size distribution. In Oak Creek, the median grain size shows the largest change with increasing flow stresses, followed by D₆₀, and so on to D₉₅ which shows the smallest change. The variations in D_m continue this trend, and are similar to those for D₉₅. This systematic variation of grain-size percentiles in Oak Creek is consistent with changes in the overall distributions which tend to be symmetrical and Gaussian for low discharges, but become skewed Rosin distributions for high discharges. In contrast, in Great Eggleshope Beck the several percentiles and D_m show the same rate of shift to coarser sizes as flow stresses increase. This results in part from differences in sampling techniques wherein the bedload samples from Great Eggleshope Beck represent a complete flood event, while shorterterm samples at a specific flow stage were obtained in Oak Creek. As a result of the integrated sampling in Great Eggleshope Beck, the bedload grain-size distributions are more complex, commonly with a bimodal pattern. However, after accounting for differences in sampling schemes in the two streams, contrasting patterns in changing grain-size distributions remain, and these are concluded to reflect grain sorting differences as the bedload grain-size distributions approach the distributions of the bed materials. It is surprising that if criteria commonly employed to demonstrate the equal mobility of different grain sizes are used in the comparison, then Great Eggleshope Beck is far closer to this condition in spite of its minimal development of a pavement. It is concluded that the respective shapes of the bed-material grain-size distributions, in particular their degrees of skewness, are more important to the observed sorting patterns than are the effects of a pavement layer regulating grain entrapment to produce an equal mobility of different grain sizes. Therefore, the comparison has established that flow-competence relationships will differ from one stream to another, depending on the pattern of grain sorting which is a function of the bedmaterial grain-size distribution.     

Acid-base activity of live bacteria: Implications for quantifying cell wall charge

To distinguish the buffering capacity associated with functional groups in the cell wall from that resulting from metabolic processes, base or acid consumption by live and dead cells of the Gram-negative bacterium Shewanella putrefaciens was measured in a pH stat system. Live cells exhibited fast consumption of acid (pH 4) or base (pH 7, 8, 9, and 10) during the first few minutes of the experiments. At pH 5.5, no acid or base was required to maintain the initial pH constant. The initial amounts of acid or base consumed by the live cells at pH 4, 8, and 10 were of comparable magnitudes as those neutralized at the same pHs by intact cells killed by exposure to gamma radiation or ethanol. Cells disrupted in a French press required higher amounts of acid or base, due to additional buffering by intracellular constituents. At pH 4, acid neutralization by suspensions of live cells stopped after 50 min, because of loss of viability. In contrast, under neutral and alkaline conditions, base consumption continued for the entire duration of the experiments (5 h). This long-term base neutralization was, at least partly, due to active respiration by the cells, as indicated by the build-up of succinate in solution. Qualitatively, the acid-base activity of live cells of the Gram-positive bacterium Bacillus subtilis resembled that of S. putrefaciens. The pH-dependent charging of ionizable functional groups in the cell walls of the live bacteria was estimated from the initial amounts of acid or base consumed in the pH stat experiments. From pH 4 to 10, the cell wall charge increased from near-zero values to about −4 × 10⁻¹⁶ mol cell⁻¹ and −6.5 × 10⁻¹⁶ mol cell⁻¹ for S. putrefaciens and B. subtilis, respectively. The similar cell wall charging of the two bacterial strains is consistent with the inferred low contribution of lipopolysaccharides to the buffering capacity of the Gram-negative cell wall (of the order of 10%).     

The use of sorting curves in studying K2O alteration in interbedded greywacke and argillite

The chemical composition of unaltered greywacke-argillite sequences varies both abruptly and gradationally across short distances of a few centimeters to meters. These original variations are sufficient to mask changes in K₂O (and other oxides) resulting from hydrothermal alteration. Sorting curves for unaltered samples present K₂O contents in terms of two relatively immobile oxides SiO₂ and Al₂O₃. This allows an estimated of the original pre-alteration K₂O content of altered samples, from which gains and losses can then be calculated.     

Preservation of water samples for arsenic(III/V) determinations: an evaluation of the literature and new analytical results

Published literature on preservation procedures for stabilizing aqueous inorganic As(III/V) redox species contains discrepancies. This study critically evaluates published reports on As redox preservation and explains discrepancies in the literature. Synthetic laboratory preservation experiments and time stability experiments were conducted for natural water samples from several field sites. Any field collection procedure that filters out microorganisms, adds a reagent that prevents dissolved Fe and Mn oxidation and precipitation, and isolates the sample from solar radiation will preserve the As(III/V) ratio. Reagents that prevent Fe and Mn oxidation and precipitation include HCl, H₂SO₄, and EDTA, although extremely high concentrations of EDTA are necessary for some water samples high in Fe. Photo-catalyzed Fe(III) reduction causes As(III) oxidation; however, storing the sample in the dark prevents photochemical reactions. Furthermore, the presence of Fe(II) or SO₄ inhibits the oxidation of As(III) by Fe(III) because of complexation reactions and competing reactions with free radicals. Consequently, fast abiotic As(III) oxidation reactions observed in the laboratory are not observed in natural water samples for one or more of the following reasons: (1) the As redox species have already stabilized, (2) most natural waters contain very low dissolved Fe(III) concentrations, (3) the As(III) oxidation caused by Fe(III) photoreduction is inhibited by Fe(II) or SO₄.     

我国耕地保护经济补偿机制实践分析

对我国部分地区试行耕地保护经济补偿机制的实践作了初步总结,从补偿对象、补偿标准、资金来源、资金使用等方面分析了各自特点,依据资金来源和补偿对象阐述了补偿实践中的不同模式。结合上海实际,提出了完善新增建设用地土地有偿使用费使用、落实基本农田保护基金、加强土地管理基础业务工作,以进一步促进耕地和基本农田保护补偿机制完善的建议。     

天山山脉剥露程度与矿产保存关系初探

成矿后含矿地质体的剥露程度与矿体的保存关系是矿床学研究的疑难问题之一.利用中酸性侵入岩体的出露程度, 结合磷灰石裂变径迹测试结果及现今发现的矿产展布特征, 探讨天山山脉剥露程度与内生金属矿产保存之间的关系, 进而为区域找矿提供理论指导.统计结果表明, 北天山西段的依连哈比尕尔山、中段的博格达山和西南天山山脉皆缺乏大面积分布的深成侵入岩, 已经发现的内生金属矿产较少, 且以中低温的矿床为主; 北天山南部的觉罗塔格地区、中天山和南天山东段都大面积出露中酸性岩体, 已经发现了大量大型-超大型规模内生金属矿床, 以中高温成矿为特征; 综合分析已有的磷灰石裂变径迹测年结果统计显示, 北天山西段的依连哈比尕山、中段的博格达山和西南天山中生代晚期开始隆升, 新生代25 Ma以来隆升强烈; 北天山南部、中天山以及南天山东段山脉从侏罗纪早期就已经开始隆升而接受剥蚀, 新生代隆升较弱.结合现今山脉的地质背景、内生金属矿产展布特征、山脉隆升时间及其现今地貌特征推测, 北天山西段的依连哈比尕山、中段的博格达山和西南天山山脉由于剥蚀时间短, 因而其剥蚀程度相对较低, 地表仍出露表壳的沉积-火山岩系, 以中酸性侵入岩体为代表的深成岩体由于剥蚀量不够而还没有出露于地表, 地表出露低温的内生金属矿产; 北天山南部、中天山以及南天山东段山脉开始隆升时间早, 新生代隆升弱, 因而总体上剥蚀量、剥蚀程度大, 表壳岩系已经剥蚀殆尽, 广泛出露深成侵入岩体, 与中酸性岩体侵位有关的中高温矿产广泛展布.为此, 进一步指出了在天山山脉不同构造分区内应该着重寻找不同类型、不同成矿温度的内生金属矿产, 推测西南天山具有较好的找矿远景空间, 并认为山体剥露程度的差异是造成所谓"大矿不过国界"的主要原因之一.      

中国南方海相含油气保存单元的层次划分与综合评价

以最近十年中国南方的海相新区油气勘探评价成果为依托 ,以油气成藏和整体封闭保存体系评价为核心 ,在渝东—湘鄂西、中下扬子和滇黔桂三大区域划分出 9个有利区块 5 1个含油气保存单元 ,并将其归纳为四个层次。综合评价认为 ,方西和石柱保存单元具有较好的整体封存体系 ,属持续性含油气保存单元 ,为首选勘探目标 ;江汉盆地南部、句容—海安区块、南鄱阳坳陷、楚雄盆地东北部具备或基本具备整体封存条件 ,属于沉积重建型含油气保存单元 ,通过精细勘探可望获得商业性油气流 ;楚雄盆地西北部、南盘江坳陷、十万大山盆地和渝东—湘鄂西地区利川复向斜由于晚期强烈构造改造而仅存在部分封存体系 ,需要攻关探索 ;思茅、渝东—湘鄂西地区的花果坪和桑植—石门地区已失去整体封闭保存条件 ,仅局部存在封存体系 ,地质条件高度复杂 ,勘探风险甚高。     

基于重砂鉴定技术的火山岩锆石精选与测年方法关系探讨

针对中浅变质沉凝灰岩锆石U-Pb同位素年龄分散幅度较大的现状,在湘中地区碧溪长安组底部凝灰岩几次采集样品测年不成功的情况下再次取样,通过室内重砂样品加工分选等工序,利用立体显微镜和偏光显微镜对锆石进行详细的矿物学特征对比分析,确定样品是否有来自不同时代、不同成因或不同地质背景的锆石.将精选出的锆石进行再次分选,分离成两组样品送往测年,采用LA-ICP-MS U-Pb法测得同沉积期的火山岩岩浆成因锆石年龄751±5 Ma和构造岩浆热事件年龄431.3± 4.3 Ma,两组年龄数据与区域地质事实吻合.由此认为对此类样品的锆石进行成因、形态与光学性质等方面的综合分析研究,将混合锆石进行分组,有助于同位素测年数据的有效集中,保证测年数据精度.本文研究表明重砂精细分析鉴定是同位素精准定年的基础.     

U-Th dating of Lake Lisan (late Pleistocene dead sea) aragonite and implications for glacial east Mediterranean climate change

U-series dating can be an effective means to obtain accurate and precise ages on Quaternary carbonates. However, most samples require a correction for U and Th in admixed detritus. This complication is often addressed through generation of U-Th isochrons, requiring analyses of several coeval samples. In addition, presence of water-derived (hydrogenous) Th in the carbonate can cause inaccuracies in isochron ages.This study reports a high-resolution U-series chronology of sediments deposited by Lake Lisan, the last glacial precursor of the Dead Sea. The strategy employed combines multiple measurements from a few stratigraphic heights and fewer analyses from many heights in a single described and measured section. The resulting chronology is based on ages at 22 heights in a ∼40-m-thick section covering the interval of ∼70-14 calendar ka BP. The effects of admixed detritus are evaluated using trace elements. Nearly pure aragonite samples, indicated by very low abundances of insoluble elements such as Nb and Zr, were found to contain hydrogenous Th, which causes the uncorrected U-²³⁰Th age of a modern sample to be ∼2.5 ka. Nevertheless, accurate ages have been obtained by correcting for the detrital and aqueous interferences. The resulting ages are in stratigraphic order, and their accuracy is evidenced by consistency of Lisan Formation U-series and ¹⁴C ages with the coral-based calendar-radiocarbon age calibration.The U-Th ages provide a context to unravel the limnological history of Lake Lisan. Boundaries between the Lower, Middle, and Upper stratigraphic units correspond to the MIS 4/3 and 3/2 transitions, respectively. During MIS 2 and 4 the lake generally showed a stable two-layer configuration and a positive fresh-water balance, reflected by deposition of laminated aragonite-detritus. Dry intervals during MIS 2 and 4 are indicated by thick gypsum layers and an inferred depositional hiatus, which are temporally associated with Heinrich events H1 at ∼17 ka and H6 at ∼65 ka, respectively. During MIS 3 the lake level was unstable with intermittent dry periods indicated by abundant clastic layers and a significant hiatus between ∼43-49 ka. Clastic layers are associated with Dansgaard-Oeschger events during MIS 3, and indicate lake level declines during abrupt Northern Hemisphere warmings. Overall, the climate of the Eastern Mediterranean region shows a strong linkage to the Northern Hemisphere climate, with increasing lake size and stability during cold periods, and fluctuations and dessication during warmings and Heinrich events.     

中国南方海相地层油气保存条件综合评价技术体系探讨

中国南方海相地层的油气藏分别在加里东、印支和燕山期经历了多期多阶段的演变过程,被构造活动改造的强度大。油气保存条件破坏严重,且缺乏有效的评价方法。本文试图通过研究地下流体的化学-动力学行为规律,从动态和演化的角度分析剥蚀作用、断裂-破碎作用、大气水下渗作用等对油气藏破坏的程度、方式,综合评价油气的成藏、保存条件,探索针对南方海相地层油气保存条件评价的技术体系。     

Preservation of thermophilic mixed culture for anaerobic palm oil mill effluent treatment by convective drying methods

The generation of huge amount of liquid waste known as palm oil mill effluent is a major problem in oil palm industry. Meanwhile, anaerobic biodegradation of such organic effluent at thermophilic condition is a promising treatment technology due to its high efficiency. However, storage and transportation of thermophilic mixed culture sludge are challenging due to constant biogas generation and heating requirement. Hence, drying of thermophilic sludge was conducted to obtain dormant thermophiles and thus enables easier handling. In this study, thermophilic sludge was dried using heat pump at 22 and 32 °C as well as hot air oven at 40, 50, 60, and 70 °C. Subsequently, quality of dried sludge was examined based on most probable number enumeration, chemical oxygen demand, and methane yield. Average drying rate was found to increase from 3.21 to 17.84 g H₂O/m² min as drying temperatures increases while average moisture diffusivity values ranges from 5.07 × 10^?9 to 4.34 × 10^?8 m²/s. Oven drying of thermophilic mixed culture resulted in highest chemical oxygen demand removal and lowest log reduction of anaerobes at 53.41% and 2.16, respectively, while heat pump drying resulted in the highest methane yield and lowest log reduction of methanogens at 53.4 ml CH₄/g COD and 2.09, respectively. To conclude, heat pump at 22 °C was most suitable drying technique for thermophilic mixed culture as the original methane-producing capability was largely retained after drying, at a slightly lower yet still comparable chemical oxygen demand removal when palm oil mill effluent was treated with the rehydrated culture.     

Lower Crustal Magma Genesis and Preservation: a Stochastic Framework for the Evaluation of Basalt-Crust Interaction

We present a quantitative assessment of the thermal and dynamicresponse of an amphibolitic lower crust to the intrusion ofbasaltic dike swarms in an arc setting. We consider the effectof variable intrusion geometry, depth of intrusion, and basaltflux on the production, persistence, and interaction of basalticand crustal melt in a stochastic computational framework. Distinctmelting and mixing environments are predicted as a result ofthe crustal thickness and age of the arc system. Shallow crustal(30 km) environments and arc settings with low fluxes of mantle-derivedbasalt are likely repositories of isolated pods of mantle andcrustal melts in the lower crust, both converging on daciticto rhyodacitic composition. These may be preferentially rejuvenatedin subsequent intrusive episodes. Mature arc systems with thickercrust (50 km) produce higher crustal and residual basaltic meltfractions, reaching 0·4 for geologically reasonable basaltfluxes. The basaltic to basaltic andesite composition of bothcrustal and mantle melts will facilitate mixing as the networkof dikes collapses, and Reynolds numbers reach 10^–4–1·0in the interiors of dikes that have been breached by ascendingcrustal melts. This may provide one mechanism for melting, assimilation,storage and homogenization (MASH)-like processes. Residual mineralassemblages of crust thickened by repeated intrusion are predictedto be garnet pyroxenitic, which are denser than mantle peridotiteand also generate convective instabilities where some of thecrustal material is lost to the mantle. This reconciles thethinner than predicted crust in regions that have undergonea large flux of mantle basalt for a prolonged period of time,and helps explain the enrichment of incompatible elements suchas K₂O, typical of mature arc settings, without the associatedmass balance problem. KEY WORDS: crustal anatexis; delamination; lower crust; magma mixing; thermal model     

Preservation strategies for avoidance of salt crystallisation in El Paular Monastery cloister, Madrid, Spain

El Paular Monastery (eleventh century) is one of the most important Carthusian monasteries in Spain and is highly affected by crystallisation of Mg-sulphates, together with chlorides and nitrates. Urgent remediation of the decay process is needed to guarantee the stability of the building materials from the cloister and to make their hallways suitable for the exhibition of an important collection of seventeenth century paintings. This paper aims to characterise the building materials, salts and their interaction to suggest preservation strategies to minimise the impact of salts both in the short and the long term. These strategies include architectural solutions (such as a ventilation system to avoid increasing dampness and hence the dissolution, mobilisation and crystallisation of salts), petrophysical-based solutions (i.e. exploiting the porosity differences between building materials and poultices to maximise salt reduction) and strategies based on the physicochemical behaviour of salts and relative humidity transfer through the stone (to determine the most suitable environmental conditions to prevent crystallisation of the most harmful salt species). This research represents both a practical and experimental exercise that is useful for conservation scientists and restorers involved in the field of preservation of monuments, and for environmental control to avoid salt crystallisation.     

In the footsteps of Alexander the Great: searching for the origins of ancient zooplankton on the wild steppe of Central Asia

Rising above the modern town of Nurata, in Navoiy Province, eastern Uzbekistan is the ancient fortress of Alexander the Great, built as part of Alexander's campaigns to subjugate the Persian‐speaking Sogdian peoples that lived in this province of the Persian Empire in the 4th Century bc . Alexander passed this way in 327 bc , marching his ancient army through this beautiful but desolate landscape, and conquering all before him. His fortress was built in a strategic place at the boundary between fertile agricultural lands and a dry and uncompromising vastness of steppe that lies to the east. From Nurata, about one hour drive by car along a road that cuts eastwards across the desert, is the sleepy town of Jo'sh. In the mountains beyond Jo'sh sits the hamlet of Kanda, a few mud‐brick houses nestling at the head of a small valley where a spring emerges miraculously from a bone‐dry landscape. Hereabouts are telltale signs of ancient marine deposits yielding graptolites from rocks of the Silurian system. And in these rocks are the fossils of tiny arthropods that mark a fundamental shift in the marine arthropod zooplankton 425 million years ago. It is these fossils that we have chased halfway across the world to the steppe of Central Asia.