Changxun Yu

Changxun Yu
Linnaeus University | lnu · Department of Biology and Environmental Science

PhD

About

77
Publications
17,389
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Introduction
My research mainly focuses on biogeochemical processes of Fe and Mn as well as their (i) impacts on mobility, transport and environmental fate of potentially toxic or biologically critical trace elements (e.g., U, As, REEs, and Ni); and (ii) links to cycling of carbon, silicon, and macronutrients (e.g., P and S).
Additional affiliations
January 2015 - December 2018
Linnaeus University
Position
  • Postdoc
July 2010 - December 2014
Linnaeus University
Position
  • PhD Student

Publications

Publications (77)
Article
Underground repository in crystalline bedrock is a widely-accepted solution for long-term disposal of spent nuclear fuels. During future deglaciations, meltwater will intrude via bedrock fractures to the depths of future repositories where O2 left in the meltwater could corrode metal-canisters and enhance the migration of redox-sensitive radionucli...
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Coastal wetlands host large and dynamic reservoirs of organic carbon (C) and are also biogeochemical hotspots for a wide range of Fe (hydr-)oxides with different chemical reactivities, properties, and functions. The cycling of these iron (hydr-)oxides is closely coupled to that of organic C, which in turn strongly influences the magnitude and dynam...
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As critical transition zones between the land and the sea, estuaries are not only hotspots of hydrogeochemical and microbial processes/reactions, but also play a vital role in processing and transferring terrestrial fluxes of metals and nutrients to the sea. This study focused on three estuaries in the Gulf of Bothnia. All of them experience freque...
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In a boreal acidic sulfate-rich subsoil (pH 3–4) developing on sulfidic and organic-rich sediments over the past 70 years, extensive brownish-to-yellowish layers have formed on macropores. Our data reveal that these layers (“macropore surfaces”) are strongly enriched in 1 M HCl-extractable reactive iron (2–7% dry weight), largely bound to schwertma...
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This study exposes U(VI)-sorbed schwertmannite and jarosite to biotic reductive incubations under field-relevant conditions and examines the changes in aqueous and solid-phase speciation of U, Fe, and S as well as associated microbial communities over 180 days. The chemical, X-ray absorption spectroscopy, X-ray diffraction, and microscopic data dem...
Article
Desert riparian ecosystems play a critical role in carbon cycling in arid regions. As a natural barrier between deserts and oases, riparian vegetation reduces the wind’s erosive effect on the soil through its leaves and branches, while its roots stabilize soil nutrients. However, the relative importance of plant- and microbial-derived carbon (C) fo...
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Fine‐grained hypermonosulfidic sediments are widespread on the coastal plains of the northern Baltic Sea that when drained, cause the formation and dispersion of acid and toxic‐metal species. In this study, a 30‐month laboratory oxidation experiment with such a sediment was performed in incubation cells. To minimize or prevent acidification, limest...
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Biogenic silica (biogenic Si) is a bioactive component crucial for the biogeochemical cycling of Si in terrestrial and aquatic ecosystems. Its formation and dissolution dynamics are intricately linked to carbon (C) cycling. However, knowledge about the source, composition, and factors controlling the distribution of biogenic Si in coastal wetland s...
Article
Coastal wetlands play a vital role in carbon (C) sequestration, named ‘blue carbon’. The review aims to disentangle the processes and influencing factors, including elevated atmospheric CO2, global climate warming, sea level rise and anthropogenic activities. Firstly, we provided an overview of C processes, including input, output, and deposition,...
Article
Coastal wetlands are key players in mitigating global climate change by sequestering soil organic matter. Soil organic matter consists of less stable particulate organic matter (POM) and more stable mineral-associated organic matter (MAOM). The distribution and drivers of MAOM and POM in coastal wetlands have received little attention, despite the...
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Aims Previous studies have shown that silicon (Si) can affect plant growth and yield by regulating the availability of other nutrients. However, the mechanisms by which Si affects plant biomass accumulation in coastal wetlands are not well explored. Methods We conducted a sampling campaign across the whole growing season of Phragmites australis un...
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Copper (Cu) is a bio-essential element and a potentially toxic pollutant in the plant–soil systems. Analysis of stable Cu isotopes can be a powerful tool for tracing the biogeochemical cycling of Cu in plant–soil systems. In this review, we examined the analysis method of stable Cu isotope ratios in plants and soils, and discussed the biogeochemica...
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Coastal wetlands contribute to the mitigation of climate change through the sequestration of “blue carbon”. Microbial necromass, lignin, and glycoproteins (i.e., glomalin-related soil proteins (GRSP)), as important components of soil organic carbon (SOC), are sensitive to environmental change. However, their contributions to blue carbon formation a...
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Acid sulfate soils are sulfide-rich soils with notable associated environmental risks. The low pH of these soils mobilizes metals from the soil minerals, which will lead to both acidification and metal contamination of the surrounding environment. This paper presents the results of a geochemical study of 66 profiles of acid sulfate soils collected...
Article
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Copper (Cu) isotopes are utilized to track Cu geochemical cycling in weathered gleysols of tropical zones. A significant isotope fractionation of Cu in these soils is primarily redox‐controlled; however, it is rarely reported how the frequency of redox fluctuations affects the soil Cu isotope signature. This study investigated the variations of Cu...
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Acid sulfate soils are sulfide-rich soils that pose a notable environmental risk as their strong acidity and low pH mobilizes metals from soil minerals leading to both acidification and metal contamination of the surrounding environment. In this study a rapid and cost-efficient approach was developed to resolve the main distribution patterns and ge...
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Aims The natural abundances of stable carbon (C) and nitrogen (N) isotopes (δ¹³C and δ¹⁵N) are extensively used to indicate the C and N biogeochemical cycles at large spatial scales. However, the spatial patterns of δ¹³C and δ¹⁵N in plant-soil systems of grasslands in northern China and their main driving factors across regional climatic gradient a...
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Acid sulfate soils discharge large amounts of sulfuric acid along with toxic metals, deteriorating water quality and ecosystem health of recipient waterbodies. There is thus an urgent need to develop cost-effective and sustainable measures to mitigate the negative effects of these soils. In this study, we flushed aseptically-prepared MQ water (refe...
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The presence of high levels of carcinogenic metalloid arsenic (As) in the groundwater system of Bangladesh has been considered as one of the major environmental disasters in this region. Many parts of Bangladesh have extensively reported the presence of high levels of arsenic in the groundwater due to both geological and anthropogenic activities. I...
Article
Soil organic carbon (SOC) in coastal wetlands, also known as ‘blue C’, is an essential component of the global C cycles. To gain a detailed insight into blue C storage and controlling factors, we studied 142 sites across ca. 5000 km of coastal wetlands, covering temperate, subtropical and tropical climates in China. The wetlands represented 6 veget...
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To bring life back to anoxic coastal and sea basins, reoxygenation of anoxic/hypoxic zones has been proposed. This research focuses on the metals released during the oxidization of sediments from two locations in the anoxic Eastern Gotland Basin under a laboratory-scale study. Triplicate experimental cores and reference cores were collected from th...
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PurposeThe karst region in southwestern China is undergoing soil erosion and rocky desertification. The different silicon (Si) fractions along the hillslopes in this mountainous region could benefit plant growth and alleviate the ecological deterioration. However, extensive distribution of carbonate rocks may lead to limited plant available Si. The...
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This study explores the reuse of spent coffee-grounds (SCGs) and the use of dissolved humic acid (DHA) to remediate acid sulfate (AS) soil drainage using adsorption and precipitation experiments, with changing pH, weight/volume, and concentrations (mg/L of dissolved organic carbon). In addition, this study aims to extend the usability of the SCGs,...
Article
Phytolith carbon (C) sequestration plays a key role in mitigating global climate change at a centennial to millennial time scale. However, previous estimates of phytolith-occluded carbon (PhytOC) storage and potential in China's grasslands have large uncertainties mainly due to multiple data sources. This contributes to the uncertainty in predictin...
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This study re-assess the environmental impacts of the Dexing copper mine (the largest open-pit copper mine in Asia) on the Lean river and its two tributaries (the Dawu river and Jishui river) in the Jiangxi province, China, with particular focus on metal pollution as well as the effectiveness and side-effects of remediation activities. Results show...
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Extensive red/brown precipitates of unknown origin and composition have caused ecological degradation of a wetland nature reserve (the Water Kingdom Biosphere Reserve) in the hemiboreal zone in south Sweden. Chemical analyses of samples containing the precipitates showed strong dominates of Fe and elevated levels of rare earth elements (REEs), Be,...
Preprint
Full-text available
Aims The natural abundances of stable carbon (C) and nitrogen (N) isotopes (δ¹³C and δ¹⁵N) are extensively used to indicate the C and N biogeochemical cycles at large spatial scales. However, the spatial patterns of δ¹³C and δ¹⁵N in plant-soil system of grasslands in northern China and their main driving factors are still not well understood. Metho...
Article
Silicon (Si) is beneficial for rice health and production by alleviating various biotic and abiotic stresses. However, the continual export of grain off-farm may result in Si deficiency for rice plants. The current levels of plant available Si (PASi) in rice paddies in China remain unclear, as do the factors that control PASi content in these soils...
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All files excluding the SRA datafiles are provided at the following figshare: 10.6084/m9.figshare.16574222 Qiime2 installation wget https://data.qiime2.org/distro/core/
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Manganese oxides occur in a wide range of environmental settings either as coatings on rocks, sediment, and soil particles, or as discrete grains. Although the production of biologically mediated Mn oxides is well established, relatively little is known about microbial-specific strategies for utilizing Mn in the environment and how these affect the...
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To understand the past carbon accumulation of forest-steppe ecotone and to identify the main drivers of the long-term carbon dynamics, we selected Huangqihai Lake and analyzed the sediment records. We measured the organic carbon content (TOC; %) of sedimentary samples and quantified the carbon accumulation rate (CAR; g C m −2 yr −1). Furthermore, t...
Article
Black shales are characterized by a high content of organic carbon (C). Few studies have focused on the influence of land use on soil organic C (SOC) fractions from soils derived from black shale (black shale soils). The objective of this study was to elucidate the influence of land use on SOC fractions in black shale soils combining chemical deter...
Article
Despite increasing recognition of the critical role of coastal wetlands in mitigating climate change, sea-level rise and salinity increase, soil organic carbon (SOC) sequestration mechanisms in estuarine wetlands remain poorly understood. Here, we present new results on the source, decomposition and storage of SOC in estuarine wetlands with four ve...
Article
Despite increasing recognition of the critical role of coastal wetlands in mitigating climate change, sea-level rise and salinity increase, soil organic carbon (SOC) sequestration mechanisms in estuarine wetlands remain poorly understood. Here, we present new results on the source, decomposition and storage of SOC in estuarine wetlands with four ve...
Article
Despite increasing recognition of the critical role of coastal wetlands in mitigating climate change, sea‐level rise and salinity increase, soil organic carbon (SOC) sequestration mechanisms in estuarine wetlands remain poorly understood. Here, we present new results on the source, decomposition and storage of SOC in estuarine wetlands with four ve...
Article
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The concentrations, loads and speciation of rare earth elements (REEs) were studied in a 3.5 m thick mud depositional succession from an estuary in the Gulf of Bothnia. The uppermost 182.5 cm of the mud, estimated to have deposited from the early 1970s to 2011 (sampling year), had very high REE concentrations (596−1456 ppm) and accumulation rates (...
Article
The soil stable carbon (C) and nitrogen (N) isotopes are widely used to indicate C 3 /C 4 vegetation history, N sources and transformation processes, respectively. However, land use change, particularly converting forest into farm land, alters soil organic matter (SOM) sources and processes in soils, resulting in a hard understanding of soil C and...
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Background and aimsSilicon (Si) deficiency is a major constraint on rice production. The objective of this study was to evaluate the long-term influence of phytolith-rich straw return and groundwater table management on labile Si fractions in paddy soil and subsequent plant Si uptake.MethodsA field experiment was conducted over 36 years in subtropi...
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Silicon (Si) plays an important role in improving soil nutrient availability and plant carbon (C) accumulation and may therefore impact the biogeochemical cycles of C, nitrogen (N), and phosphorus (P) in terrestrial ecosystems profoundly. However, research on this process in grassland ecosystems is scarce, despite the fact that these ecosystems are...
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Changes in climate and land use are causing grasslands to suffer increasingly from abiotic stresses, including soil salinization. Silicon (Si) amendment has been frequently proposed to improve plant resistance to multiple biotic and abiotic stresses and increase ecosystem productivity while controlling the biogeochemical carbon (C) cycle. However,...
Article
Carbon (C) present in lake sediments is an important global sink for CO2; however, an in-depth understanding of the impact of climate variability and the associated changes in vegetation on sediment C dynamics is still lacking. A total of 13 lakes were studied to quantify the influence of climate and vegetation on the reconstructed Holocene C accum...
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Purpose: Phytolith-occluded carbon (PhytOC) is mainly derived from the products of photosynthesis, which can be preserved in soils and sediments for hundreds-to-thousands of years due to the resilient nature of the amorphous phytolith silica. Therefore, stable and radioactive carbon (C) isotopes of phytoliths can be effectively utilized in paleoeco...
Article
Silicon (Si) is one of the most abundant elements in the Earth’s crust but its role in governing the biogeochemical cycling of other elements remains poor understood. There is a paucity of information on the role of Si in wetland plants, and how this may alter wetland C production and storage. Therefore, this study investigated Si distribution, nut...
Article
Due to land uplift after the last ice age, previously stable Baltic Sea sulfidic sediments are becoming dry land. When these sediments are drained, the sulfide minerals are exposed to air and can release large amounts of metals and acid into the environment. This can cause severe ecological damage such as fish kills in rivers feeding the northern B...
Article
This study assessed Fe-isotope ratio (56Fe/54Fe, expressed as δ56Fe relative to the IRMM-014 standard) variability and controls in pyrite that has among the largest reported S-isotope variability (maximum δ34S: 140‰). The pyrite occurs as fine-grained secondary crystals in fractures throughout the upper kilometer of granitoids of the Baltic Shield,...
Article
The weathering of U and/or Th rich granite plutons, which occurs worldwide, may serve as a potentially important, but as yet poorly defined source for U and Th in (sub-)surface environments. Here, we assessed the impact of an outcrop of such granite (5 km in diameter) and its erosional products on the distribution of U and Th in four nemo-boreal ca...
Article
Grassland ecosystems play an important role in the global terrestrial silicon (Si) cycle, and Si is a beneficial element and structural constituent for the growth of grasses. In previous decades, grasslands have been degraded to different degrees because of the drying climate and intense human disturbance. However, the impact of grassland degradati...
Article
Crop harvesting and residue removal from croplands often result in imbalanced biogeochemical cycles of carbon and nutrients in croplands, putting forward an austere challenge to sustainable agricultural production. As a beneficial element, silicon (Si) has multiple eco-physiological functions, which could help crops to acclimatize their unfavorable...
Article
Beryllium (Be) sources, transport and sinks were studied in a coastal landscape where acidic soils (acid sulfate soils) have developed after drainage of fine-grained sulfide-bearing sediments. The study included the determination of total abundance and speciation of Be in a variety of solid and aqueous materials in both the terrestrial and estuarin...
Article
This study investigated interfacial reactions between aqueous Ce(III) and two synthetic nanosized Mn (hydr-) oxides (manganite: γ-MnOOH, and vernadite: δ-MnO2) in the absence and presence of Nordic Lake fulvic acid (NLFA) at circumneutral pH by batch experiments and cryogenic X-ray photoelectron spectroscopy (XPS). The surfaces of manganite and ver...
Article
This study focuses on the mechanisms of Ce sequestration and accumulation in the fracture network of the upper kilometer of the granitoid bedrock of the Baltic Shield in southeast Sweden (Laxemar area, Sweden). The material includes 81 specimens of bulk secondary mineral precipitates (“fracture coatings”) collected on fracture walls identified in 1...
Article
This study focuses on fluorine (F) concentrations and solid-phase speciation in Quaternary deposits, including till, sorted sediments (gravel, sand, clay/silt) and organic-rich soil types, in an area in southeast Sweden underlain by 1.8 Ga granites and quartz monzodiorites with moderate F concentrations (0.11–0.13 wt%) and an outcrop (5 km in diame...
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This study examines the spatial and temporal distribution patterns of arsenic (As) in solid and aqueous materials along the mixing zone of an estuary, located in the south-eastern part of the Bothnian Bay and fed by a creek running through an acid sulfate (AS) soil landscape. The concentrations of As in solution form (< 1 kDa) increase steadily fro...
Article
Dissolved (<1 kDa) and colloidal (1 kDa-0.45 μm) size fractions of sulfate, organic carbon (OC), phosphate and 17 metals/metalloids were investigated in the acidic Vörå River and its estuary in Western Finland. In addition, geochemical modelling was used to predict the formation of free ions and complexes in these waters. The sampling was carried o...
Article
This paper reports a geochemical study on the major and trace elements and Pb-Sr isotopes of a weathering profile developed in the Lower Cambrian black shales in central Hunan (China). Six weathering horizons were identified and sampled vertically throughout the profile. The chemical composition of the profile consists of variable concentrations of...
Article
The dispersion of acidic solutions with high levels of metals/metalloids, as a result of oxidative weathering of pyritic geomaterials, is a major environmental problem in areas where these materials are widely distributed and/or were historically mined. In this study, four types of materials encountered in an old black-shale mining area (unweathere...
Article
The geochemistry of major and trace elements (including heavy metals and rare earth elements) of the fresh and weathered black shales, and the soils derived from black shales in the Ganziping mine area in western Hunan province (China) were studied using the following techniques: X-ray fluorescence (XRF), inductively coupled plasma mass spectromete...
Article
This paper reports a geochemical study on major and trace elements in maize grown on the black shale soils in Dongping and Yanxi areas of the Anhua County, central Hunan Province, China. Contents of elements in mazie were analyzed using ICP-MS techniques. The results show that, although the enrichment and the assemblage of elements in the soils of...
Article
This paper reports a geochemical study of trace metals and Pb isotopes of sediments from the lowermost Xiangjiang River, Hunan province (P. R. China). Trace metals Ba, Bi, Sc, V, Cr, Mn, Co, Ni, Cu, Zn, Mo, Cd, Sn, Sb, Pb, Tl, Th, U, Zr, Hf, Nb and Ta were analyzed using ICP-MS, and Pb isotopes of the bulk sediments were measured by MC-ICP-MS. The...
Article
This paper examines the geochemical features of 8 soil profiles developed on metalliferous black shales distributed in the central parts of the South China black shale horizon. The concentrations of 21 trace elements and 8 major elements were determined using ICP-MS and XRF, respectively, and weathering intensity (W) was calculated according to a n...
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We conducted geochemical analysis on soils derived from the Lower-Cambrian black shales in Dongping and Yanxi areas of the Anhua County, central Hunan (China) by sampling six soil profiles. Concentrations of major and trace elements (including heavy metals and rare earth elements) of the soil samples and relative parent rocks were measured using IC...
Article
The acid mine drainage (AMD) discharged from the Hejiacun uranium mine in central Hunan (China) was sampled and analyzed using ICP-MS techniques. The analyzing results show that the AMD is characterized by the major ions FeTotal, Mn, Al and Si, and is concentrated with heavy metals and metalloids including Cd, Co, Ni, Zn, U, Cu, Pb, Tl, V, Cr, Se,...
Article
This study carried out a geochemical approach on heavy-metal contamination of soils derived from black shale (balck-shale soils) from the HJC uranium mine in central Hunan, China. Four soil profiles numbered as A, B, C and D were surveyed and sampled. The concentrations of major elements, heavy metals, and other trace elements as well as rare earth...
Article
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Using electronic microprobe, the mineralogical study of samples from level 29 of V3 vein of the Woxi deposit in western Hunan province shows that the ore minerals include major native gold, stibnite, sphalerite and Sb-Pb mineral phase. The mineralogical assemblage of the deep ore is more complicated than those of the shallow levels. The native gold...
Article
The concentrations of heavy metals in black shale and soils derived from the black shale in central Hunan Province, China, were measured using ICP-MS technique. The relationship between characteristics of the black shale and the heavy metal contaminations of its overlaid soil was investigated in this study. The results showed that the black shale w...
Article
The mineralogy and geochemistry of the waste rocks distributed at Taojiang Mn-ore deposit, central Hunan province, China, were studied using X-ray powder diffraction (XRD), electron microprobe analysis (EMPA) fitted with energy dispersive spectrometer (EDS) and inductively coupled plasma mass spectrum (atomic emission spectra) ICP-MS (AES), with th...