Glacial–interglacial productivity and environmental changes in Lake Biwa,Japan: A sediment core study of organic carbon,chlorins and biomarkers

Temporal changes in paleoproductivity of Lake Biwa (Japan) over the past 32 kyr have been studied by analyzing bulk organic carbon and photosynthetic pigments (chlorins) in the BIW95-5 core. Primary productivity was estimated on the assumption of C/N_org values of 8 for autochthonous organic matter (OM) and 25 for allochthonous OM and using an equation developed for the marine environment. The estimate indicates that primary productivity ranges from 50 to 90 g C m^?2 yr^?1 in the Holocene, while it is ～60 g C m^?2 yr^?1 on average in the last glacial. Pheophytin a and pheophorbide a are the major chlorins. A downcore profile of chlorin concentration normalized to autochthonous organic carbon (OC) shows a decreasing trend. Chlorin productivity was corrected by removal of the effect of post-burial chlorin degradation. The temporal profile of chlorin productivity thereby obtained resembles that from autochthonous OC.The difference in primary productivity between the Holocene and the glacial for the lake is markedly smaller than that for Lake Baikal situated in the boreal zone. This difference between the two lakes is probably caused by the difference in their climatic conditions, such as temperature and precipitation. Precipitation at Lake Biwa is relatively large during the glacial and the Holocene because of the continuous influence of the East Asian monsoon. Lake Baikal precipitation is generally small as a result of control by the continental (Siberia) climate regime. In addition, a significant difference in productivity between the glacial and the Holocene for Lake Baikal may be essentially controlled by the hydrodynamic systems in the lake.Lake Biwa terrigenous OM input events occurred at least five times over the period 11–32 kyr BP, suggesting enhanced monsoon activity. Molecular examination of the layer with a large input of terrigenous OM during the Younger Dryas indicates that concentrations of terrigenous biomarkers such as n-C₂₇–C₃₁ alkanes, lignin phenols, cutin acids, ω-hydroxy acids and C₂₉ sterols are high, suggesting that soil OM with peat-like material entered the lake as a result of flooding. An enhanced sedimentation rate in the last 3000 years might have been partially caused by agricultural activity around the lake.     

A 200–300 year cyclicity in sediment deposition in the Gotland Basin,Baltic Sea,as deduced from geochemical evidence

During the EU funded project BASYS (Baltic Sea System Study) short (Niemistö-type) and long (box and piston cores) sediment cores were taken which cover sedimentation during the past 8 ka. The uppermost part of the sedimentary sequence was chosen for a detailed geochemical study and freeze dried samples were analysed for about 20 elements but only the elements Mn and Ca are discussed. An age model was constructed using radiometric dating results by ²¹⁰Pb/¹³⁷Cs and ¹⁴C AMS. Significant correlation exists along the cores between very high Mn and moderately high Ca due to occrrences of the mineral rhodochrosite (kuthnahorite), a complex Mn(Ca) carbonate. This mineral is thought to be produced when salt water meets the pool of dissolved Mn at the bottom of the Gotland Basin. During favourable hydrographic conditions, e.g. strong northwesterly winds, salt water from the North Sea invades even the deepest parts of the central Baltic. Mn²⁺ which is produced mainly by the dissolution of ferromanganse oxides/oxyhydroxides in the water colum and in the course of destruction of organic matter in the sediments, combines with HCO₃^2- and Ca²⁺ in the seawater to form rhodochrosite. After burial, this mineral stays in the sediment and is seen as light-coloured layers. A certain cyclicity in the upper 1.5 m of the cores was observed in that about 200–300 a periods of elevated Mn–Ca are followed by periods with lower Mn–Ca of similar duration. An explanation for the observed cyclicity may be sea level variations: during rising sea level (transgression) more and more saline water is pushed into the deep basin of the Baltic Sea and if conditions are favourable (high dissolved Mn) the mineral rhodochrosite is precipitated.     

Halogens and noble gases in sedimentary formation waters and Zn–Pb deposits: A case study from the Lennard Shelf,Australia

Halogen ratios (Br/Cl and I/Cl) and concentrations provide important information about how sedimentary formation waters acquire their salinity, but the possible influence of organic Br derived from sedimentary wall-rocks is rarely quantified. Here, it is demonstrated that Br/Cl versus I/Cl mixing diagrams can be used to deconvolve organic Br contributions; that organic matter has a limited range of Br/I ratios; and that organic Br is a more significant component in Zn–Pb deposit ore fluids than previously recognised. The significance of these findings is illustrated for the Lennard Shelf Zn–Pb deposits of Western Australia.Fluid inclusions related to Lennard Shelf Zn–Pb mineralisation have variable salinity and hydrocarbon contents. The halogen data from these fluid inclusions require mixing of three fluid end-members: (1) an evaporated seawater bittern brine (30 wt.% NaCl equiv.) with greater than seawater Br/Cl ratio; (2) a lower salinity pore fluid (?5 wt.% NaCl equiv.) with moderately elevated Br/Cl and I/Cl; and (3) fluids with Br/Cl ratios of ～5 times seawater and extremely elevated I/Cl ratios of ～11,500 times seawater. The first two fluids have ⁴⁰Ar/³⁶Ar of 300–400 and greater than air saturated water ³⁶Ar concentrations that are typical of fluid inclusions related to Zn–Pb mineralisation. The third ‘organic-rich’ fluid has the highest ⁴⁰Ar/³⁶Ar ratio of up to 1500 and a depleted ³⁶Ar concentration.Mineralisation is interpreted to have resulted from mixing of Zn-rich evaporitic brines and H₂S present in hydrocarbons. It is suggested that aqueous fluids acquired organic Br and I from hydrocarbons, and that hydrocarbons exsolving from the aqueous fluid removed noble gases from solution. Interaction of variably saline brines and hydrocarbons could account for the variable Br/Cl and I/Cl composition, and ³⁶Ar concentrations, recorded by Lennard Shelf fluid inclusions. The distinct ⁴⁰Ar/³⁶Ar signature of the fluid with the highest I/Cl ratio suggests the hydrocarbons and brines were sourced independently from different parts of the sedimentary basin. These data indicate the complementary nature of halogen and noble gas analysis and provide new constraints on important mixing processes during sediment-hosted Zn–Pb mineralisation.     

Metallogenic efficiency from deposit to region–A case study in western Zhejiang Province,southeastern China

Metallogenic (ore) efficiency can be defined as the ratio of metal reserves to its total supply, and we expanded a typical efficiency-calculation model available at the single mineral scale to the regional scale. A new cell-based model was developed by analogy and by taking some other influences into account: i) a thicker sedimentary cover; ii) regional ore- and rock-controlling structures and their intersections; iii) the crustal heterogeneity unrelated and related to ores; and iv) metallic geochemical anomalies. Finally, a regional contour map of weighted efficiency, which is essential to metallogenic prediction, was obtained. It shows that the efficiency anomalies can provide a much better target area for ore-positioning than do metallic content anomalies, and greater ore efficiency may indicate the likelihood of occurrence of mineral deposits that are larger in size (reserves). Taking northwestern Zhejiang province as a case study, in which the geochemistry of Mesozoic porphyries plausibly show considerable mineralized potential, we found that due to the lower magmatic temperature, delayed exsolution of the hydrothermal solution, and very thick sedimentary cover, the Cu-polymetal ore efficiency associated with granitic plutons in this area is generally low; the relatively higher ore-productivity (efficiency) appears mainly in and around small rock bodies, rock margins, and the contacting zone between different lithologies. Most ore spots, no matter their size, fall into areas with nonzero efficiency values. There seems to be no interdependence between most ore spots of smaller size and ore efficiency, whereas efficiency is essential to regional small- and medium-scaled metallogensis.     

A study of outburst activity of Z and in 2000–2010

We present the results of our study of the classical symbiotic star Z And during its period of activity in 2000–2010. In this period, the system experienced a series of six outbursts, for three of which high-resolution spectra were obtained and analyzed. These observations provided information about the system’s behavior during the entire activity period, rather than during an individual outburst. In particular, we found a fundamental difference between the first outburst, which initiated the activity period, and subsequent outbursts, namely, the presence of bipolar collimated optical outflows for some of the outbursts. We propose a model that can explain all the spectroscopic phenomena observed during this series of outbursts, as well as previous series of outbursts of Z And, and suggest that similar scenarios may be valid for other classical symbiotic stars.     

Cattle-based livelihoods,changes in the taskscape,and human–bear conflict in the Ecuadorian Andes

Cattle-raising, especially for dairy, has expanded in the Ecuadorian Andes since the late 1990s as smallholding farmers have shifted their livelihood activities away from crop-based agriculture due to changes in climate, market conditions, and rural out-migration. Non-migrants constructing cattle-based livelihoods are turning to cattle as the basis for “viable” livelihoods in order to remain in depopulating rural parishes. Non-migrant farmers express ideals such as autonomy and tranquility as reasons for their attachment to rural places. In turn, their livelihood activities remake these places materially. Drawing on Tim Ingold’s conceptualization of taskscape and landscape, I argue that cattle-based livelihoods create a taskscape prone to human–wildlife conflict. Since 2009, residents have reported dozens of Andean bear attacks on cattle. Cattle are vulnerable capital assets. They represent both an investment with daily and weekly dividends over many years, in the form of milk, and a long-term form of wealth storage. The turn to cattle-based livelihoods in this region has thus heightened human–bear conflict. The phenomenon of the human–bear conflict is therefore a product of shifting livelihoods and accompanying changes in the taskscape. This analysis demonstrates the importance of listening to narratives of place attachment and accounting for the cultural logics of livelihood choices when considering interventions to address human–wildlife conflict.     

Delineation of fresh aquifers in tannery belt for sustainable development — A case study from southern India

The tannery effluents discharged by the existing units on either side of the Palar river at Ambur town (known for tannery industry), has resulted in vertical and lateral spread of pollution. The study area of 55.3 km² is situated on a granitic terrain of Archaean age with undulating topography and hillocks. The shallow aquifers, in flood plain and valley fills of the river are highly polluted (with EC: 15340 μS/cm) by tannery effluents making groundwater unfit for any use, hence the local population (20000) face health hazards and shortage of potable water. Hydrogeological, geophysical and in-situ groundwater quality measurement were carried out to demarcate fresh groundwater zones and to delineate lateral and vertical extent of pollution. The results show, brackish aquifer was characterized by low order of resistivity (<20 Ω-m) with a thickness of 8.5 to 28 m located in the flood plains, valley fills, and partially in hard rock formations, whereas the fresh water aquifer resistivity varying from 23 to 216 Ω-m in hard rock. Further, these results were correlated with the water quality data and Ground Penetrating Radar (GPR) signals. The integrated studies revealed that pollution due to tannery effluents has spread over an area of 33.4 km² (60.4 %) on either side of the river and only a small area of 21.9 km² (39.6 %) was identified as fresh groundwater zone, which has to be conserved and exploited in sustainable manner for future generations.     

Understanding regional development mechanisms in Greater Beijing Area,China, 1995–2001, from a spatial–temporal perspective

Due to its rapid economic gains in recent decades, studies of China’s regional development have recently attracted scholarly attentions. Multi-scalar and multi-mechanism are proposed as crucial approaches in China’s regional studies. More advanced methodological development in GIS and spatial analysis also lends power to in-depth understanding of China’s regional development. This study examines the development mechanisms from a spatial–temporal perspective in Greater Beijing Area (GBA), China. In particular, with panel data of GBA from 1995 to 2001 at county level, the study intends to apply a spatial panel regression analysis to study the well identified regional development mechanisms, namely, institutional factors, globalization and urbanization. Based on the panel data analysis, a tentative geographically and temporally weighted regression (GTWR) is also proposed to explore the potentially varying relationships between economic development and its mechanisms from a space–time standpoint. Results from the analyses are quite interesting. First, when urbanization seems to hinder regional development in GBA with cross-sectional analysis, the spatial panel analysis indicates that urbanization contributes to GBA’s development in the 7 years span. Second, per capita foreign investment, which was usually deemed one of the major factors of globalization and a financial engine for regional development in the reform China, turns out to be a negligible mechanism in GBA’s development. Third, among all the development mechanisms, the government’s financial capability seems to dominate the regional development in GBA. GTWR analysis further revealed potential non-stationary relationships among the modeled variables, indicating that the functions of regional development mechanisms are inherently heterogeneous both spatially and temporally in GBA.     

The role of tectonic shear strain on the illitization mechanism of mixed-layers illite–smectite. A case study from a fault zone in the Northern Apennines,Italy

The influence of tectonic strain on the diagenetic degree and illitization process of mixed-layers illite–smectite at shallow crustal conditions was studied. For this purpose, the modal composition of clay fraction and illite FWHM parameters of argillites deformed by a regional-scale fault zone were studied in detail by XRD, chemical analyses and by SEM observations. Analyses were performed on deformed samples of the fault rock and compared with the non-deformed rocks off the fault zone. In addition, this paper reports a detailed comparative analysis of deformed (shear surfaces and cleavage domains) and non-deformed domains (lithon cores) of a scaly fabric in the fault rock. A systematic increase in illite concentration, a decrease of Kübler index and FWHM₍₀₀₂₎ values, and an enrichment of K⁺ ions were observed in cleavage domains with respect to the non-deformed sediments off the fault zone and the lithon cores within the fault rock. Migration of K⁺-rich fluids along scaly cleavage domains causes progressive conversion of smectite-rich I–S to illite-rich I–S and thickening of illite crystallites along the c-direction. Changes in mineralogical and crystallographic parameters, therefore, seem to be strongly controlled by shear plane development in highly sheared rocks.     

Long-term groundwater storage changes and land subsidence development in the North China Plain (1971–2015)

The North China Plain (NCP) has been suffering from groundwater storage (GWS) depletion and land subsidence for a long period. This paper collects data on GWS changes and land subsidence from in situ groundwater-level measurements, literature, and satellite observations to provide an overview of the evolution of the aquifer system during 1971–2015 with a focus on the sub-regional variations. It is found that the GWS showed a prolonged declining rate of ?17.8?±?0.1 mm/yr during 1971–2015, with a negative correlation to groundwater abstraction before year ~2000 and a positive correlation after ~2000. Statistical correlations between subsidence rate and the GWS anomaly (GWSA), groundwater abstraction, and annual precipitation show that the land subsidence in three sub-regions (Beijing, Tianjin, and Hebei) represents different temporal variations due to varying driver factors. Continuous drought caused intensive GWS depletion (?76.1?±?6.5 mm/yr) and land subsidence in Beijing during 1999–2012. Negative correlations between total groundwater abstraction and land subsidence exhibited after the 1980s indicate that it may be questionable to infer subsidence from regional abstraction data. Instead, the GWSA generally provides a reliable correlation with subsidence. This study highlights the spatio-temporal variabilities of GWS depletion and land subsidence in the NCP under natural and anthropogenic impacts, and the importance of GWS changes for understanding land subsidence development.     

A smoothed particle hydrodynamics modelling of soil–water mixing and resulting changes in average strength

Soil–water interaction is a pivotal process in many underwater geohazards such as underwater landslides where soil sediments gradually evolve into turbidity currents after interactions with ambient water. Due to the large deformations, multiphase interactions and phase changes this involves, investigations from numerical modelling of the transition process have been limited so far. This study explores a simple numerical replication of such soil–water mixing with respect to changes in average strength using smoothed particle hydrodynamics (SPH). A uniform viscoplastic model is used for both the solid-like and fluid-like SPH particles. The proposed numerical solution scheme is verified by single-phase dam break tests and multiphase simple shear tests. SPH combinations of solid-like and fluid-like particles can replicate the clay–water mixture as long as the liquidity index of the solid-like particles is larger than unity. The proposed numerical scheme is shown to capture key features of an underwater landslide such as hydroplaning, water entrainment and wave generation and thus shows promise as a tool to simulate the whole process of subaquatic geohazards involving solid–fluid transition during mass transport.     

Spatial–temporal changes in meteorological and agricultural droughts in Northeast China: change patterns,response relationships and causes

Natural Hazards - Under the background of climate warming, drought events occur frequently. Generally, meteorological drought leads to agricultural drought. Understanding the spatiotemporal...     

The Water Framework Directive: Can more information be extracted from groundwater data? A case study of Seewinkel,Burgenland, eastern Austria

Water protection is one of the most important goals in environmental protection. The Clean Water Act in the USA and the Water Framework Directive (WFD) in Europe are the legal frameworks to facilitate the achievement of this goal. The question is raised of whether more information can be extracted from WFD-related groundwater data. To answer it, a methodology has been developed that is easy to use and could be implemented into official practice. A case study is presented in which the groundwater data of a sodic area in Austria (Seewinkel) is assessed. Eighteen parameters in groundwater sampled from 23 wells (1991–2011) were analyzed. With basic statistics, trend-, cluster-, Wilks’ λ and spatial sampling density analysis, local phosphorus and boron phenomena were described, along with the determining role of sulphate, groundwater flow, and the oxygen gradient in the area. As a final step, the spatial sampling density was determined. Regarding the current set of parameters, all the sampling sites are necessary and only in the case of certain parameters (Ca²⁺, Mg²⁺, K⁺, NO₃ ^?, pH) could one sampling site be abandoned. The methodology applied brings a new perspective to exploring groundwater data collected according to the requirements of the WFD.     

Ion microprobe U–Th–Pb geochronology and study of micro-inclusions in zircon from the Himalayan high- and ultrahigh-pressure eclogites,Kaghan Valley of Pakistan

We report ion microprobe U–Th–Pb geochronology of in situ zircon from the Himalayan high- and ultrahigh-pressure eclogites, Kaghan Valley of Pakistan. Combined with the textural features, mineral inclusions, cathodoluminescence image information and the U–Th–Pb isotope geochronology, two types of zircons were recognized in Group I and II eclogites. Zircons in Group I eclogites are of considerably large size (>100 μm up to 500 μm). A few grains are euhederal and prismatic, show oscillatory zoning with distinct core–rim luminescence pattern. Several other grains show irregular morphology, mitamictization, embayment and boundary truncations. They contain micro-inclusions such as muscovite, biotite, quartz and albite. Core or middle portions of zircons from Group I eclogites yielded concordant U–Th–Pb age of 267.6 ± 2.4 Ma (MSWD = 8.5), have higher U and Th contents with a Th/U ratio > 1, indicating typical magmatic core domains. Middle and rim or outer portions of these zircons contain inclusions of garnet, omphacite, phengite and these portions show no clear zonation. They yielded discordant values ranging between 210 and 71 Ma, indicating several thermal or Pb-loss events during their growth and recrystalization prior to or during the Himalayan eclogite-facies metamorphism. Zircons in Group II eclogites are smaller in size, prismatic to oval, display patchy or sector zoning and contain abundant inclusions of garnet, omphacite, phengite, quartz, rutile and carbonates. They yielded concordant U–Th–Pb age of 44.9 ± 1.2 Ma (MSWD = 4.9). The lower U and Th contents and a lower Th/U ratio (<0.05) in these zircons suggest their formation from the recrystallization of the older zircons during the Himalayan high and ultrahigh-pressure eclogite-facies metamorphism.     

A structural,magnetic, and Mössbauer spectral study of several Na–Mn–Fe-bearing alluaudites

The synthesis and the chemical, structural, magnetic, and Mössbauer spectral characterization of three synthetic alluaudites, Na₂Mn₂Fe(PO₄)₃, NaMn Fe₂(PO₄)₃ and Na₂MnFe^IIFe^III(PO₄)₃, and a natural sample with the nominal composition of NaMn Fe₂(PO₄)₃, collected in the Buranga pegmatite, Rwanda, are reported. All four compounds have the expected alluaudite monoclinic C2/c structure with the general formula [A(2)A(2)][A(1)A(1)A(1)₂]M(1)M(2)₂(PO₄)₃ in which manganese(II) is on the M(1) site and manganese(II), iron(III) and, in some cases, iron(II) on the M(2) site. The X-ray structure of Na₂Mn₂Fe(PO₄)₃ also indicates a partially disordered distribution of Na^I and Mn^II on the M(1) and A(1) crystallographic sites. All four compounds are paramagnetic above 40 K and antiferromagnetically ordered below. Above 40 K the effective magnetic moments of NaMnFe₂(PO₄)₃ and Na₂MnFe^IIFe^III(PO₄)₃ are those expected of high-spin manganese(II) and iron(III) with the ⁶A_1g electronic ground state and high-spin iron(II) with the ⁵T_2g electronic ground state. In contrast, the effective magnetic moment of Na₂Mn₂Fe(PO₄)₃ is lower than expected as a result of enhanced antiferromagnetic exchange coupling by the manganese(II) on the M(2) site. The Mössbauer spectra of all four compounds have been measured from 4.2 to 295 K and have been found to be magnetically ordered below 40 K for Na₂Mn₂Fe(PO₄)₃ and 35 K for the remaining compounds. The Mössbauer spectra of Na₂Mn₂Fe(PO₄)₃ exhibit the two expected iron(III) quadrupole doublets and/or magnetic sextets expected for a random distribution of manganese(II) and iron(III) ions on the M(2) site. Further, the Mössbauer spectra of Na₂MnFe^IIFe^III(PO₄)₃ exhibit the two iron(II) and two iron(III) quadrupole doublets and/or magnetic sextets expected for a random distribution of iron(II) and iron(III) on the M(2) site. Surprisingly, the synthetic and natural samples of NaMnFe₂(PO₄)₃ have 19 and 10% of iron(II) on the M(2) site; apparently the presence of some iron(II) stabilizes the alluaudite structure through the reduction of iron(III)–iron(III) repulsion. The temperature dependence of the iron(II) quadrupole splitting yields a 440 to 600 cm^–1 low-symmetry component to the octahedral crystal field splitting at the M(2) site. The iron(II) and iron(III) hyperfine fields observed at 4.2 K are consistent with the presence of antiferromagnetic ordering at low temperatures in all four compounds.     

A petrologic, geochemical and Sr–Nd isotopic study on contact metamorphism and degassing of Devonian evaporites in the Norilsk aureoles, Siberia

Devonian evaporites and associated sedimentary rocks in the Norilsk region were contact metamorphosed during emplacement of mafic sills that form part of the end-Permian (~252 Ma) Siberian Traps. We present mineralogical, geochemical and Sr–Nd isotopic data on sedimentary rocks unaffected by metamorphism, and meta-sedimentary rocks from selected contact aureoles at Norilsk, to examine the mechanisms responsible for magma-evaporite interaction and its relation to the end-Permian environmental crisis. The sedimentary rocks include massive anhydrite, rock salt, dolostone, calcareous siltstones and shale, and the meta-sedimentary rocks comprise calcareous hornfels, siliceous hornfels and minor meta-anhydrite and meta-sandstone. Contact metamorphism took place at low pressure and at maximum temperatures corresponding to the phlogopite-diopside stability field. Calcareous hornfels have high CaO, MgO, CΟ₂, SΟ₃, low SiO₂ and initial Sr isotopic ratios of 0.7079–0.7092, features indicative of calcareous siltstone protoliths. Siliceous hornfels, in contrast, have high SiO₂, Al₂O₃, Na₂O, low in other major element oxides and initial Sr isotopic ratios of 0.7083–0.7152, consistent with pelitic or shaley protoliths. Loss of CO₂ in a subset of calcareous hornfels can be explained by decarbonation reactions during metamorphism, but release of SO₂ from evaporites cannot be accounted for by a similar mechanism. Occurrences of wollastonite and a variety of hydrous minerals in the calcareous hornfels are consistent with equilibration with hydrous fluid, which was capable of leaching large quantities of anhydrite in the presence of dissolved NaCl. In this way, substantial sediment-derived sulfur could have been mobilized, incorporated into the magmatic system and released to the atmosphere. The release of CO₂ and SO₂ from Siberian evaporites added to the variety of toxic gases generated during metamorphism of organic matter, coal and rock salt, contributing to the end-Permian environmental crisis.     

A comparison study of the C–A and S–A models with singularity analysis to identify geochemical anomalies in covered areas

Fractal/multifractal modeling of geochemical data is an interesting topic in the field of applied geochemistry. Identification of weak anomalies for mineral exploration in covered areas is one of the most challenging tasks for utilization of geochemical data. In this study, three fractal models, consisting of the concentration–area (C–A), spectrum–area (S–A) and singularity index models were applied to identify geochemical anomalies in the covered area located in the Chaobuleng Fe polymetallic district, Inner Mongolia (China). The results show that (1) the grassland cover weakens the concentrations of geochemical elements; (2) the C–A model has a limitation to identify weak anomalies in covered areas; (3) the S–A model is a powerful tool to decompose mixed geochemical patterns into a geochemical anomaly map and a varied geochemical background map but suffers edge effects in an irregular shaped study area; and (4) the singularity index is a useful tool to identify weak geochemical anomalies.