scholarly journals The unique Abramovka REE-rich mineralization is a potential source of REE for the Pavlovsk coals deposit (Primorsky Krai, Russia)

2019 ◽  
Vol 98 ◽  
pp. 01007
Author(s):  
Igor Chekryzhov ◽  
Irina Tarasenko ◽  
Elena Vakh ◽  
Sergey Vysotsky
Keyword(s):  
Surface Waters ◽  
Volcanic Rocks ◽  
Geochemical Data ◽  
Similar Distribution ◽  
Humic Matter ◽  
Primorsky Krai ◽  
Peat Accumulation ◽  
Near Surface ◽  
Ree Mineralization ◽  
Potential Source

The unique REE mineralization of the Abramovka ore occurrence, associated near-surface waters, and REE-rich coals of the Pavlovka basin were studied. The authors, on the base of new isotope-geochemical data and K-Ar dating, suggest that the Abramovka REE minerals (hydrocarbonates, hydrophosphates and hydroxides) formed as a result of interaction of the Palaeozoic metasedimentary and Mesozoic volcanic rocks with near-surface waters. In the Pavlovka metalliferous coals, REE are concentrated predominantly in a humic matter that sorbed REE from water solutions during the peat accumulation stage. A similar distribution of REE in the Abramovka ores, associated near-surface waters, and metalliferous coals of the Pavlovka basin suggest that the Abramovka-type mineralization might be a major source of REE enrichment in the Pavlovka coals.

Phosphorus Leaching Under Cut Grassland

1999 ◽  
Vol 39 (12) ◽  
pp. 63-67 ◽  
Author(s):  
B. L. Turner ◽  
P. M. Haygarth
Keyword(s):  
Surface Waters ◽  
Large Scale ◽  
Agricultural Land ◽  
Algal Growth ◽  
Soil Types ◽  
P Fractions ◽  
Inorganic P ◽  
Potential Source ◽  
Significant Mechanism ◽  
Total P

Phosphorus (P) transfer from agricultural land to surface waters can contribute to eutrophication, excess algal growth and associated water quality problems. Grasslands have a high potential for P transfer, as they receive P inputs as mineral fertiliser and concentrates cycled through livestock manures. The transfer of P can occur through surface and subsurface pathways, although the capacity of most soils to fix inorganic P has meant that subsurface P transfer by leaching mechanisms has often been perceived as negligible. We investigated this using large-scale monolith lysimeters (135 cm deep, 80 cm diameter) to monitor leachate P under four grassland soil types. Leachate was collected during the 1997–98 drainage year and analysed for a range of P fractions. Mean concentrations of total P routinely exceeded 100 μg l−1 from all soil types and, therefore, exceeded P concentrations above which eutrophication and algal growth can occur. The majority of the leachate P was in algal-available Mo-reactive (inorganic) forms, although a large proportion occurred in unreactive (organic) forms. We suggest that subsurface transfer by leaching can represent a significant mechanism for agricultural P transfer from some soils and must be given greater consideration as a potential source of diffuse P pollution to surface waters.

scholarly journals Leaching Rate of Polychlorinated Biphenyls (PCBs) from Marine Paint Chips

2021 ◽  
Author(s):  
Allen D. Uhler ◽  
Jeffery H. Hardenstine ◽  
Deborah A. Edwards ◽  
Guilherme R. Lotufo
Keyword(s):  
Polychlorinated Biphenyls ◽  
Surface Waters ◽  
Leaching Rate ◽  
Short Term ◽  
Aroclor 1254 ◽  
Maintenance And Repair ◽  
Potential Source ◽  
Vessel Bottom ◽  
Dissolved Phase ◽  
Over Time

AbstractPolychlorinated biphenyls (PCBs) were added to certain marine vessel bottom paints as a plasticizer to improve the adhesion and durability of the paint. The most common PCB formulation used to amend such paints was Aroclor 1254. Fugitive Aroclor-containing paint chips generated from vessel maintenance and repair operations represent a potential source of PCB contamination to sediments. Limited published studies indicate that Aroclor-containing paint is largely inert and exhibits low PCB leaching into water; however, the rate and degree of leaching of PCBs from paint chips have not been directly studied. This laboratory-based study evaluated the rate and extent of leaching of PCBs from paint chips into freshwater. The results of this investigation demonstrate that the rate of PCB dissolution from paint chips decreased rapidly and exponentially over time. Based on this study, it is estimated that the rate of leaching of PCBs from paint chips would cease after approximately 3 years of exposure to water. When all leachable PCBs were exhausted, it is estimated that less than 1% of the mass of PCBs in the paint chips was amenable to dissolution. The results of this experiment suggest that Aroclor-containing paint chips found in sediments are likely short-term sources of dissolved-phase PCB to pore or surface waters and that the majority of the PCBs in paint chips remain in the paint matrix and unavailable for partitioning into water. Graphic Abstract

Early Cretaceous crust–mantle interaction linked to rollback of the Palaeo-Pacific flat-subducting slab: constraints from the intermediate–felsic volcanic rocks of the northern Great Xing’an Range, NE China

2021 ◽  
pp. 1-22
Author(s):  
Jia-Hao Jing ◽  
Hao Yang ◽  
Wen-Chun Ge ◽  
Yu Dong ◽  
Zheng Ji ◽  
...  
Keyword(s):  
Early Cretaceous ◽  
Volcanic Rocks ◽  
Geochemical Data ◽  
Calc Alkaline ◽  
Ne China ◽  
Asthenospheric Mantle ◽  
High K ◽  
Wide Range ◽  
Great Xing’An Range ◽  
Subducting Slab

Abstract Late Mesozoic igneous rocks are important for deciphering the Mesozoic tectonic setting of NE China. In this paper, we present whole-rock geochemical data, zircon U–Pb ages and Lu–Hf isotope data for Early Cretaceous volcanic rocks from the Tulihe area of the northern Great Xing’an Range (GXR), with the aim of evaluating the petrogenesis and genetic relationships of these rocks, inferring crust–mantle interactions and better constraining extension-related geodynamic processes in the GXR. Zircon U–Pb ages indicate that the rhyolites and trachytic volcanic rocks formed during late Early Cretaceous time (c. 130–126 Ma). Geochemically, the highly fractionated I-type rhyolites exhibit high-K calc-alkaline, metaluminous to weakly peraluminous characteristics. They are enriched in light rare earth elements (LREEs) and large-ion lithophile elements (LILEs) but depleted in high-field-strength elements (HFSEs), with their magmatic zircons ϵHf(t) values ranging from +4.1 to +9.0. These features suggest that the rhyolites were derived from the partial melting of a dominantly juvenile, K-rich basaltic lower crust. The trachytic volcanic rocks are high-K calc-alkaline series and exhibit metaluminous characteristics. They have a wide range of zircon ϵHf(t) values (−17.8 to +12.9), indicating that these trachytic volcanic rocks originated from a dominantly lithospheric-mantle source with the involvement of asthenospheric mantle materials, and subsequently underwent extensive assimilation and fractional crystallization processes. Combining our results and the spatiotemporal migration of the late Early Cretaceous magmatic events, we propose that intense Early Cretaceous crust–mantle interaction took place within the northern GXR, and possibly the whole of NE China, and that it was related to the upwelling of asthenospheric mantle induced by rollback of the Palaeo-Pacific flat-subducting slab.

scholarly journals Comparison of dry and wet deposition of particulate matter in near-surface waters during summer

PLoS ONE ◽  
2018 ◽  
Vol 13 (6) ◽  
pp. e0199241 ◽  
Author(s):  
Yanan Wu ◽  
Jiakai Liu ◽  
Jiexiu Zhai ◽  
Ling Cong ◽  
Yu Wang ◽  
...  
Keyword(s):  
Particulate Matter ◽  
Surface Waters ◽  
Wet Deposition ◽  
Near Surface ◽  
Dry And Wet Deposition

scholarly journals Formation environments and mechanisms of multistage paleokarst of Ordovician carbonates in Southern North China Basin

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Haitao Zhang ◽  
Guangquan Xu ◽  
Mancai Liu ◽  
Minhua Wang
Keyword(s):  
Carbonate Rocks ◽  
North China ◽  
Oil And Gas ◽  
Carbonate Reservoir ◽  
Carbonate Reservoirs ◽  
Geochemical Data ◽  
Near Surface ◽  
Oil And Gas Exploration ◽  
Pore Types ◽  
North China Basin

AbstractWith the reduction of oil and gas reserves and the increase of mining difficulty in Northern China, the carbonate rocks in Southern North China Basin are becoming a significant exploration target for carbonate reservoirs. However, the development characteristics, formation stages, formation environments and mechanisms of the carbonate reservoirs in Southern North China Basin are still unclear, which caused the failures of many oil and gas exploration wells. This study focused on addressing this unsolved issue from the Ordovician carbonate paleokarst in the Huai-Fu Basin, which is located in the southeast of Southern North China Basin and one of the key areas for oil and gas exploration. Based on petrology, mineralogy and geochemical data, pore types, distribution characteristics, and formation stages of the Ordovician paleokarst were analyzed. Then, in attempt to define the origins of porosity development, the formation environments and mechanisms were illustrated. The results of this study showed that pore types of the Ordovician carbonates in the Huai-Fu Basin are mainly composed of intragranular pores, intercrystalline (intergranular) pores, dissolution pores (vugs), fractures, channels, and caves, which are usually in fault and fold zones and paleoweathering crust. Furthermore, five stages and five formation environments of the Ordovician paleokarst were identified. Syngenetic karst, eogenetic karst, and paleoweathering crust karst were all developed in a relatively open near-surface environment, and their formations are mainly related to meteoric water dissolution. Mesogenetic karst was developed in a closed buried environment, and its formation is mainly related to the diagenesis of organic matters and thermochemical sulfate reduction in the Permian-Carboniferous strata. Hydrothermal (water) karst was developed in a deep-buried and high-temperature environment, where hydrothermal fluids (waters) migrated upward through structures such as faults and fractures to dissolve carbonate rocks and simultaneously deposited hydrothermal minerals and calcites. Lastly, a paleokarst evolution model, combined with the related porosity evolution processes, nicely revealed the Ordovician carbonate reservoir development. This study provides insights and guidance for further oil and gas exploration in the Southern North China Basin, and also advances our understanding of the genesis of carbonate paleokarst around the world.

Three stages of arc migration in the Carboniferous-Triassic in northern Qiangtang, central Tibet, China: Ridge subduction and asynchronous slab rollback of the Jinsha Paleotethys

2021 ◽  
Author(s):  
Yin Liu ◽  
Wenjiao Xiao ◽  
Brian F. Windley ◽  
Kefa Zhou ◽  
Rongshe Li ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Volcanic Rocks ◽  
Late Triassic ◽  
Geochemical Data ◽  
The Tibetan Plateau ◽  
Ridge Subduction ◽  
Temporal Relationships ◽  
Slab Rollback ◽  
Geodynamic Processes ◽  
Central Tibet

Carboniferous-Triassic magmatism in northern Qiangtang, central Tibet, China, played a key role in the evolution of the Tibetan Plateau yet remains a subject of intense debate. New geochronological and geochemical data from adakitic, Nb-enriched, and normal arc magmatic rocks, integrated with results from previous studies, enable us to determine the Carboniferous-Triassic (312−205 Ma), arc-related, plutonic-volcanic rocks in northern Qiangtang. Spatial-temporal relationships reveal three periods of younging including southward (312−252 Ma), rapid northward (249−237 Ma), and normal northward (234−205 Ma) migrations that correspond to distinct slab geodynamic processes including continentward slab shallowing, rapid trenchward slab rollback, and normal trenchward rollback of the Jinsha Paleotethys rather than the Longmuco-Shuanghu Paleotethys, respectively. Moreover, varying degrees of coexistence of adakites/High-Mg andesites (HMAs)/Nb-enriched basalt-andesites (NEBs) and intraplate basalts in the above-mentioned stages is consistent with the magmatic effects of slab window triggered by ridge subduction, which probably started since the Late Carboniferous and continued into the Late Triassic. The Carboniferous-Triassic multiple magmatic migrations and ridge-subduction scenarios provide new insight into the geodynamic processes of the Jinsha Paleotethys and the growth mechanism of the Tibetan Plateau.

scholarly journals Environmental control on the variability of DMS and DMSP in the Mauritanian upwelling region

2012 ◽  
Vol 9 (3) ◽  
pp. 1041-1051 ◽  
Author(s):  
C. Zindler ◽  
I. Peeken ◽  
C. A. Marandino ◽  
H. W. Bange
Keyword(s):  
Surface Waters ◽  
Coastal Upwelling ◽  
Environmental Control ◽  
Hot Spot ◽  
Local Source ◽  
Surface Seawater ◽  
Near Surface ◽  
Northwest Africa ◽  
N:P Ratios ◽  
A Minor

Abstract. Dimethylsulphide (DMS) and dissolved and particulate dimethylsulfoniopropionate (DMSPd, DMSPp) were measured in near-surface waters along the Mauritanian coast, Northwest Africa, during the upwelling season in February 2008. DMS, DMSPd and DMSPp surface concentrations of up to 10 nmol L−1, 15 nmol L−1 and 990 nmol L−1, respectively, were measured. However, the DMS concentrations measured are in the low range compared to other upwelling regions. The maximum DMSPp concentration is the highest reported from upwelling regions so far, which might indicate that the Mauritanian upwelling is a hot spot for DMSP. Within the phytoplankton groups, dinoflagellates were identified as important contributors to DMS concentrations, while other algae seemed to have only a minor or no influence on DMS and DMSP concentrations. A pronounced switch from high DMSP to high DMS concentrations was observed when the nitrogen to phosphorus ratio (N:P) was below 7. The high DMS/DMSP ratios at N:P ratios <7 indicate that nitrogen limitation presumably triggered a switch from DMSP to DMS independent of the species composition. Our results underline the importance of coastal upwelling regions as a local source for surface seawater sulphur.

scholarly journals Radiocesium in the Taiwan Strait and the Kuroshio east of Taiwan from 2018 to 2019

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Wei-Jen Huang ◽  
Ming-Ta Lee ◽  
Kuei-Chen Huang ◽  
Kai-Jung Kao ◽  
Ming-An Lee ◽  
...  
Keyword(s):  
Water Column ◽  
Surface Waters ◽  
Half Life ◽  
North Pacific Ocean ◽  
Taiwan Strait ◽  
Depth Range ◽  
Near Surface ◽  
Activity Concentrations ◽  
The Taiwan Strait ◽  
The Kuroshio

AbstractThe release of anthropogenic radiocesium to the North Pacific Ocean (NPO) has occurred in the past 60 years. Factors controlling 137Cs (half-life, 30.2 year) and 134Cs (half-life, 2.06 year) activity concentrations in the Kuroshio east of Taiwan and the Taiwan Strait (latitude 20° N–27° N, longitude 116° E–123° E) remain unclear. This study collected seawater samples throughout this region and analyzed 134Cs and 137Cs activity concentrations between 2018 and 2019. A principal component analysis (PCA) was performed to analyze the controlling factors of radiocesium. Results of all 134Cs activity concentrations were below the detection limit (0.5 Bq m−3). Analyses of water column 137Cs profiles revealed a primary concentration peak (2.1–2.2 Bq m−3) at a depth range of 200–400 m (potential density σθ: 25.3 to 26.1 kg m−3). The PCA result suggests that this primary peak was related to density layers in the water column. A secondary 137Cs peak (1.90 Bq m−3) was observed in the near-surface waters (σθ = 18.8 to 21.4 kg m−3) and was possibly related to upwelling and river-to-sea mixing on the shelf. In the Taiwan Strait, 137Cs activity concentrations in the near-surface waters were higher in the summer than in the winter. We suggest that upwelling facilitates the vertical transport of 137Cs at the shelf break of the western NPO.

scholarly journals Petrographic and geochemical data for Cenozoic volcanic rocks of the Bodie Hills, California and Nevada

Data Series ◽  
10.3133/ds764 ◽  
2013 ◽  
Author(s):  
Edward A. du Bray ◽  
David A. John ◽  
Stephen E. Box ◽  
Peter G. Vikre ◽  
Robert J. Fleck ◽  
...  
Keyword(s):  
Volcanic Rocks ◽  
Geochemical Data

scholarly journals Geochemical features and formation conditions of Early-Devonian cherty-argillaceous shales and the underlying basalts in the Ishkildino section (eastern slope of the Southern Urals)

LITOSFERA ◽  
2019 ◽  
pp. 30-47
Author(s):  
A. M. Fazliakhmetov
Keyword(s):  
Volcanic Rocks ◽  
Southern Urals ◽  
Geochemical Data ◽  
Upper Ordovician ◽  
The Southern Urals ◽  
Geochemical Composition ◽  
Early Devonian ◽  
Ocean Ridges ◽  
Clay Shales ◽  
Conodont Zone

Research subject.The West Magnitogorsk zone of the Southern Urals in the vicinity of the Ishkildino village features a subaerially exposed basaltic sequence superposed by cherts and siliceous-clay shales. The basalts and the overlying shales are assumed to have formed during the Ordovician and Silurian (?)–Early Devonian (up to the conodont zone excavates inclusive) periods, respectively. The aim of this research was to reconstruct, using geochemical data, the conditions under which the rocks present in this geological location were formed.Materials and methods. Five samples of the basalts (XRD and ICP-MS methods), 27 samples of the siliceous-clay shales and 10 samples of the cherts (XRD and ICP-AES methods) were analyzed.Results.According to the ratio of SiO2, Na2O and K2O, the volcanic rocks from the lower part of the section are represented by basalts and trachybasalts. Their geochemical composition corresponds to the N-MORB and is established to be similar to that of the basalts in the Polyakovskaya formation (the Middle–Upper Ordovician). In terms of main elements, the shales under study consist of quartz and illite with a slight admixture of organic matter, goethite, quartzfeldspar fragments, etc. The degree of the sedimentary material weathering according to the CIA, CIW and ICV index values is shown to be moderate. The values of Strakhov’s and Boström’s moduli correspond to sediments without the admixture of underwater hydrothermal vent products. The values of Cr/Al, V/Al and Zr/Al correspond to those characteristic of deposits in deep-water zones remote from the coasts of passive and active continental margins, basalt islands and areas adjacent to mid-ocean ridges. For most samples, the values of Ni/Co, V/Cr, Mo/Mn are typical of deposits formed under oxidative conditions. However, several samples from the upper part of the section, which is comparable to the kitabicus and excavatus conodont zones, demonstrate the Ni/Co, V/Cr, and Mo/Mn values corresponding to deposits formed under reducing atmospheres. An assumption is made that the existence of these deposits can be associated with the Bazal Zlichov event.Conclusion.The investigated pre-Emsian shales have shown no signs of volcanic activity in the adjacent areas. The studied deposits are established to correspond to the central part of the Ural Paleoocean.

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