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Examines the effects of rare-earth elements on physiological and chemical responses of wheat acid rain stress. Decrease of chlorophyll content and chlorophyll values; Correlation of chlorophyll values with the hydrogen ion concentration value of acid rain; Increase of chlorophyll decomposition.

Provides information on a study which examined the biological effect of rare-earth elements (REE) on antioxidation enzymes of wheat under acid rain stress. Background on the two protective enzymes, superoxide dismutase and catalase; Materials and methods; Results and discussion.

Glomalin-related soil protein (GRSP) derived from arbuscular mycorrhizal fungi can be transported from land to sea and captured in mangrove wetlands, thereby contributing to soil C and N pools. However, the stable isotope signatures of GRSP and the key influencing factors that affect its isotope values in coastal wetlands remain unknown. In this study, the results showed that total-GRSP (T-GRSP) was a significant contributor of C and N content to mangrove soil. We first compared stable isotope (δ13C and δ15N) values and C/N ratios of GRSP with those of other blue carbon sources in a typical mangrove wetland. The isotope fingerprints of T-GRSP, mangrove soils, mangrove plants, and tidal waters were identified. Unlike those of the conventional sources, the δ13C and δ15N values of T-GRSP were −25.04‰ to −22.83‰ and 3.22‰ to 7.24‰, respectively, and the mean C/N ratio was 12.95 in the mangrove cover sites. These findings indicated that T-GRSP is a novel blue carbon source mainly originating from terrestrial ecosystems. Moreover, the δ13C and δ15N values of T-GRSP in mangrove wetlands were affected by vegetation interception and soil properties. Redundancy analysis results indicated that pH, moisture, depth, and salinity were key factors influencing the T-GRSP isotope fingerprints in mangrove wetlands. Additionally, the simultaneous changes in T-GRSP content, isotope values, and C/N ratios among mangrove cover sites, a mudflat, and tidal waters suggested that this protein is a sensitive tracer between land and sea. Overall, the isotope signatures of GRSP captured by mangroves were identified for the first time, which will have important implications for the estimation of the blue carbon budget and identification of the blue carbon sources in global coastal regions. Unlabelled Image • GRSP is an important terrestrial carbon source that efficiently stores blue carbon. • δ13C and δ15N values of T-GRSP differed from those of other mangrove SOM sources. • The stable isotope values and C/N ratios of T-GRSP revealed its terrestrial origin. • T-GRSP content was significantly positively correlated with soil OC and TN content. • The simultaneous changes in characteristics showed that GRSP is a sensitive tracer. [ABSTRACT FROM AUTHOR]

Simple Summary: Tetrabromobisphenol A has been used extensively in fire-resistant materials in recent decades, and scientists have extensively investigated its toxic effects on organisms and humans. The present study aims to investigate the distribution characteristic of tetrabromobisphenol A in three mangrove swamps; analyze the associated microbial community structure involved in the tetrabromobisphenol A degradation; and explore the relationships between the microbial community and environmental factors. The results indicated mangrove sediments from the Zhangjiang Estuary, Jiulongjiang Estuary, and Quanzhou Bay in Southeast China contained high levels of tetrabromobisphenol A. Correlation analysis revealed that total organic carbon plays a critical impact on tetrabromobisphenol A distribution in the mangrove sediments. The microbial community structures of the three mangrove sediments were similar, while the taxonomic profile of their sensitive responders differed markedly. The genus Anaerolinea was dominant in the mangrove sediment and may be responsible for the in situ dissipation of tetrabromobisphenol A. Redundancy analysis indicates that combining tetrabromobisphenol A, total nitrogen, and total organic carbon would induce a shift in the microbial community structure of mangrove sediments. This work provided insight into the endogenous microbial community diversity of different mangrove sediments which may be one of the factors contributing to the different tetrabromobisphenol A concentrations. The occurrence and distribution characteristics of tetrabromobisphenol A (TBBPA) and its relationship with microbial community diversity in different mangrove sediments need further investigation. The results of this study indicated levels of TBBPA in mangrove sediments from the Zhangjiang Estuary (ZJ), Jiulongjiang Estuary (JLJ), and Quanzhou Bay (QZ) in Southeast China ranging from 1.80 to 20.46, 3.47 to 40.77, and 2.37 to 19.83 ng/g dry weight (dw), respectively. Mangrove sediments from JLJ contained higher levels of TBBPA, possibly due to agricultural pollution. A correlation analysis revealed a significant correlation between total organic carbon (TOC), total nitrogen (TN), and TBBPA distribution in ZJ and JLJ mangrove sediments, but not in QZ mangrove sediments. TOC significantly affected the distribution of TBBPA in mangrove sediments, but pH had no effect. High-throughput 16S rRNA gene sequencing showed that Pseudomonadota dominated the sediment bacteria followed by Chloroflexota, Actinobacteota, Bacillota, Acidobacteriota, Bacteroidota, and Aminicenantes in mangrove sediments. Although the microbial community structure of the ZJ, JLJ, and QZ mangrove sediments was similar, the taxonomic profile of their sensitive responders differed markedly. The genus Anaerolinea was dominant in the mangrove sediments and was responsible for the in situ dissipation of TBBPA. Based on redundancy analysis, there was a correlation between TBBPA, TOC, TN, C/N, pH, and microbial community structure at the genus level. Combining TBBPA, TN, and TOC may induce variations in the microbial community of mangrove sediments. [ABSTRACT FROM AUTHOR]

Iron‐bound soil organic carbon (Fe‐bound SOC) and microbial residues are vital for SOC preservation, a process crucial for drawdown of anthropogenic carbon. However, the relative importance of Fe‐bound SOC in coastal wetlands, and its interaction with microbial residues remain poorly understood. Here, we used glomalin as a proxy for microbial residues, with the goal of determining microbial residues binding to Fe and Fe‐bound SOC across a 1000 km coastline of China including seven typical mangrove wetlands. As hypothesized, it was found that the glomalin fraction was strongly associated with and likely bound to Fe‐bound SOC complexes, which accounted for 21.4% ± 1.6% of mangrove SOC. Mean level of Fe‐bound glomalin was 1.2 ± 0.1 mg cm−3, accounting for 40.6% ± 1.5% of total glomalin and 35.4% ± 3.2% of Fe‐bound SOC in the top 10 cm mangrove soil layer at regional scale. Due to the growing realization that Fe may be a crucial factor of glomalin cycling, we performed multiple chemical characterization techniques to identify the association between Fe and glomalin. Our results suggested that association to Fe was a main stabilization mechanism of glomalin in soils, and glomalin served as organic ligands in the formation of Fe‐bound SOC. We also found that the bulk glomalin extracts were a glomalin–Fe–OC ternary complex, which constituted an important proportion of mangrove SOC. These findings highlight the important effect of glomalin bound to Fe as a major mechanism of SOC persistence in coastal wetlands. [ABSTRACT FROM AUTHOR]

Glomalin-related soil protein (GRSP) is a significant component in the sequestration of heavy metal in soils, but its mechanisms for metal adsorption are poorly known. This study combined spectroscopic data with molecular docking simulations to reveal metal adsorption onto GRSP's surface functional groups at the molecular level. The EXAFS combined with FTIR and XPS analyses indicated that the adsorption of Cd(II), Sr(II), and Ni(II) by GRSP occurred mainly through the coordination of –OH and –COOH groups with the metal. The –COOH and –OH groups bound to the metal as electron donors and the electron density of the oxygen atom decreased, suggesting that electrostatic attraction might be involved in the adsorption process. Two-dimensional correlation spectroscopy revealed that preferential adsorption occurred on GRSP for the metal in sequential order of –COOH groups followed by –OH groups. The presence of the Ni–C shell in the Ni EXAFS spectrum suggested that Ni formed organometallic complexes with the GRSP surface. However, Sr–C and Cd–C were absent in the second shell of the Sr and Cd spectra, which was attributed to the adsorption of Sr and Cd ions with large hydration ion radius by GRSP to form outer-sphere complexes. Through molecular docking simulations, negatively charged residues such as ASP151 and ASP472 in GRSP were found to provide electrostatic attraction and ligand combination for the metal adsorption, which was consistent with the spectroscopic analyses. Overall, these findings provided new insights into the interaction mechanisms between GRSP and metals, which will help deepen our understanding of the ecological functions of GRSP in metal sequestration. [Display omitted] • Spectral data combined with molecular docking reveal adsorption mechanism of GRSP. • Metal is mainly immobilized on the GRSP surface through –OH and –COOH groups. • Preferential adsorption on GRSP for metal in sequential order of –COOH > –OH group. • ASP151 and ASP472 residues in GRSP provide coordination sites for metal adsorption. • Ni with smaller hydrated ionic radii forms organometallic complexes with GRSP. [ABSTRACT FROM AUTHOR]

Mesh-structured films formed by the post-processing of microfibers improves their permeability and dexterity, such as disposable masks. However, the aging behavior and potential risks of mesh-structured microfibers (MS-MFs) in landfill leachate remain poorly understood. Herein, the aging behavior and mechanisms of MS-MFs and ordinary polypropylene-films (PP-films) microplastics, as well as their leaching concerning dissolved organic matter (DOM) in landfill leachate were investigated. Results revealed that MS-MFs underwent more significant physicochemical changes than PP-films during the aging process in landfill leachate, due to their rich porous habitats. An important factor in the photoaging of MS-MFs was related to reactive oxygen species produced by DOM, and this process was promoted by photoelectrons under UV irradiation. Compared with PP-films, MS-MFs released more DOM and nano-plastics fragments into landfill leachate, altering the composition and molecular weight of DOM. Aged MS-MFs-DOM generated new components, and humus-like substances produced by photochemistry showed the largest increase. Correlation analysis revealed that leached DOM was positively correlated with oxygen-containing groups accumulated in aged MS-MFs. Overall, MS-MFs will bring higher environmental risks and become a new long-term source of DOM contaminants in landfill leachate. This study provides new insights into the impact of novel microfibers on landfill leachate carbon dynamics. [Display omitted] • UV light promotes the aging of MS-MFs than that of PP-films in landfills. • MS-MFs release more photoinduced humic-like DOM than PP-films into leachate. • Leached DOM is positively related with O-containing groups in aged MS-MFs. • DOM promote ROS generation, thus accelerating the aging of MS-MFs. • Aged MS-MFs aggravate the complexity of DOM in landfill leachate. [ABSTRACT FROM AUTHOR]

Dibutyl phthalate (DBP) as a plasticizer has been widely used in the processing of plastic products. Nevertheless, these DBP additives have the potential to be released into the environment throughout the entire life cycle of plastic products. Herein, the leaching behavior of DBP from PVC microplastics (MPs) in freshwater and seawater and its potential risks were investigated. The results show that the plasticizer content, UV irradiation, and hydrochemical conditions have a great influence on the leaching of DBP from the MPs. The release of DBP into the environment increases proportionally with higher concentrations of additive DBP in MPs, particularly when it exceeds 15 %. The surface of MPs undergoes accelerated oxidation and increased hydrophilicity under UV radiation, thereby facilitating the leaching of DBP. Through 30 continuous leaching experiments, the leaching of DBP from MPs in freshwater and seawater can reach up to 12.28 and 5.42 mg g-1, respectively, indicating that MPs are a continuous source of DBP pollution in the aquatic environment. Moreover, phthalate pollution index (PPI) indicates that MPs can significantly increase DBP pollution in marine environment through land and sea transport processes. Therefore, we advocate that the management of MPs waste containing DBP be prioritized in coastal sustainable development. [Display omitted] • More DBP is released from MPs with the higher concentration of DBP in MPs. • UV radiation increases the oxidation of MPs, thus promoting the leaching of DBP. • The hydrophilicity of MPs' surface can indicate their leaching capacity to DBP. • The leaching of DBP from MPs is primarily controlled by intraparticle diffusion. • MPs may be a long-term source of DBP contaminants in both freshwater and seawater. [ABSTRACT FROM AUTHOR]

• SO 4 2− can help to mitigate As mobility in flooded As-contaminated mangrove sediment. • Sulfate-modified As release variations are always accompanied by Fe/Al release. • Arsenic release was promoted at pH 11, while sulfate decreased arsenic release. • Sulfate alters As form distribution, and strongly adsorbed As increases significantly. Fragile mangrove wetlands are threatened by sea level rise, which results in the introduction of increased sulfate concentrations into mangrove sediment. Mangroves are also susceptible to heavy metal contamination, such as arsenic (As) contamination. However, little is known about whether sulfate affects the bioavailability of As in mangrove sediment. This study focuses on the effects of sulfate on arsenic mobilization and transformation in As-contaminated mangrove sediment, and modeled changes in sulfate concentration, As contamination levels, and pH conditions. The As release from sediment treated with sulfate (30 mM) significantly decreased (P < 0.05). In the moderate arsenic-contaminated sediment, the mean arsenic release was 181.95 ± 33.05 μg kg−1 without sulfate and 157.55 ± 40.98 μg kg−1 with sulfate. In addition, the release of As was affected by both pH and sulfate when pH conditions were changed. Arsenic release was promoted at pH 11 (P < 0.05), but sulfate still mitigating As release at this pH value (P < 0.001). Furthermore, the release of As after sulfate input was always accompanied by the release of iron (Fe) and aluminum (Al). Sulfate altered the distribution of forms of As in the sediment, with a significant increase in the proportion of strongly adsorbed As and silicate-bound states of As. Overall, sulfate intrusion mitigates As release, but it also increases the bioavailability of As in the sediment. This fact makes the toxic element most susceptible to long-term mobilization via biological processes. Therefore, the effect of persistent sulfate intrusion caused by sea level rise on toxic elements in mangrove sediment deserves long-term attention. The significance of this study is that it contributes to understanding the behavior of heavy metals in coastal wetland ecosystems affected by sea level rise. [ABSTRACT FROM AUTHOR]

Glomalin-related soil protein (GRSP) is a stable iron-organic carbon mixture that can enhance heavy metal sequestration in soils. However, the roles of GRSP in the transformation and fate of Cr(VI) have been rarely reported. Herein, we investigated the electrochemical and photocatalytic properties of GRSP and its mechanisms in Cr(VI) adsorption and reduction. Results showed that GRSP had a stronger ability for Cr(VI) adsorption and reduction than other biomaterials, with the highest adsorption amount of up to 0.126 mmol/g. The removal efficiency of Cr(VI) by GRSP was enhanced (4–7%) by ultraviolet irradiation due to the hydrated electrons produced by GRSP. Fe(II) ions, persistent free radicals, and oxygen-containing functional groups on the GRSP surface as electron donors participated in the reduction of Cr(VI) under dark condition. Moreover, Cr(III) was mainly adsorbed on the –COOH groups of GRSP via electrostatic interactions. Based on 2D correlation spectroscopy, the preferential adsorption occurred on the GRSP surface for Cr(VI) in the sequential order of C O → COO– → O–H → C–O. This work provides new insights into the Cr(VI) adsorption and reduction mechanism by GRSP. Overall, GRSP can serve as a natural iron-organic carbon for the photo-reduction of Cr(VI) pollution in environments. [Display omitted] • GRSP was able to remove nearly 100% of 1 mM Cr(VI) under acidic conditions. • Photoelectrochemical reduction of Cr(VI) to GRSP-Cr(III) complexes was exhibited. • UV promoted GRSP to produce more photoactive substances like electrons and e aq −. • Cr(III) in GRSP-Cr(III) complexes didn't occur reoxidation under ideal conditions. • Fe(II) and carbon-oxygen functional groups on GRSP could reduce Cr(VI) to Cr(III). [ABSTRACT FROM AUTHOR]

Pollution by magnetic particles is a rising environmental issue with possible adverse health effects such as the Alzheimer's disease. Magnetic particles in urban dust originate from traffic-related activities, industrial products and detrital minerals, yet distribution of magnetic particles in cities is poorly known. Here, we measured magnetic properties of surface roadside dust and topsoils by low-frequency magnetic susceptibility (χLF), saturation isothermal remanent magnetization (SIRM), anhysteretic remanent magnetization (χARM) and advanced rock-magnetic methods. Results show that χLF, SIRM and χARM of roadside dust are much higher than topsoil values. Roadside dusts had much lower percent frequency-dependent susceptibility of 1.83 ± 0.12% than topsoil of 2.96 ± 0.14%. Findings also demonstrate a minor contribution of fine pedogenic grains to the elevated χLF. The high values of dust χLF, SIRM and χARM are explained by the contribution of local, exogenous magnetite-like materials. [ABSTRACT FROM AUTHOR]

Iron (Fe) plaques in coastal wetlands are widely recognized because of their strong adsorption affinity for natural particles, but their interaction behaviors and mechanisms with plastics remain unknown. Through laboratory incubation experiments, paired with multiple characterization methods and microbial analysis, this work focused on the characteristics of Fe plaques on low-density polyethylene plastic surfaces and their relationship with environmental factors in coastal wetlands (Mangrove and Spartina alterniflora soil). The results showed that iron plaques increased the adhesive force of the plastic surface from 65.25 to 300 nN and promoted the oxidation of the plastic surface. Fe plaque formation was stimulated by salinity, anaerobic conditions, natural organic matter, and a weak alkaline scenario (pH 8.0–8.3). The Fe content showed a stable positive correlation with heavy metals loading (i.e., As, Mn, Co, Cr, Pb, and Zn). Furthermore, we revealed that Fe plaque was positively regulated by Nitrospirae through 16S rRNA high-throughput sequencing analysis. Meanwhile, Verrucomicrobia and Kiritimatiellaeota. may act as depressants by consuming salt. This work illustrated that iron plaques could enhance the role of plastics in contaminant migration by altering their adsorption performance, providing new insights into plastic interface behavior and potential ecological effects in coastal wetlands. [Display omitted] • Linkage between plastics/microplastics and iron plaques has been revealed. • Salinity, pH, and oxygen affect the formation of Fe plaque on plastic surfaces. • The dominant Nitrospirae is associated with forming iron plaque on plastics. • Fe plaques on the LDPE surface enhance heavy metal adsorption. • Fe plaques promote the oxidation of plastic surfaces. [ABSTRACT FROM AUTHOR]

Estuarine sedimentation is an important historical record of potentially toxic metal (PTM) emissions from human activities that can be used to improve environmental management. However, the contribution of different human activities to PTM deposition has not been accurately estimated, and their coupled relationship with riverine organic matter is typically not considered. In this study, we reconstruct the century-scale PTM depositional history of sediment cores from the Yangtze Grand Delta. Eight potential metal sources (PMSs) were identified using positive matrix factorization, and the results of lagged correlation determined the PMSs associated with the riverine discharge of the Yangtze River. Riverine PTMs were predominantly composed of Cr (79.0%), Ni (77.3%), and Pb (64.1%) but were deprived in Cu (34.9%). Glomalin-related soil protein (GRSP), which is a typical terrestrial refractory carbon, has a strong affinity for Cu, and contributed to 2.82–22.6% Cu deposition. The change in the PMS is mainly related to power generation, whereas the GRSP-bound PTM is mainly related to road construction and transportation. We advocate for responsible management of human activities in river catchments, particularly on coal-based power generation and road transportation, to maintain ecological security and promote the overall achievement of the Sustainable Development Goals. [Display omitted] • A century-scale metal deposition history of the Yangtze Delta were reconstructed. • Trends in potential metal sources with presumed changing points were identified. • Metal deposition carried by terrestrial recalcitrant organic matter was quantified. • Linkage between socio-economic indicators and metal deposition was revealed. [ABSTRACT FROM AUTHOR]

Deciphering the mobility and transfer of heavy metals in transition buffers is vital to understanding their behavior in mangrove forests. As one of the most redox-sensitive metals, the geochemical fractionation of sediment Chromium in mangrove forests and its health risks to the coastal fishermen folk is not clearly understood. This study investigated the current levels, enrichment, geochemical fractionation, and eco-toxicity on organisms of sediment Chromium from three mangrove forests in southeast China. A health risk assessment for different exposure pathways were also determined with Monte Carlo simulations technique. The results revealed that the concentration of sediment Chromium ranged from 30.75 mg kg−1 to 99.28 mg kg−1. The geochemical fractionations of sediment Chromium were mainly associated with amorphous Fe fraction, crystalline Fe fraction and residual fraction. Notably, 83.12% of samples analyzed in the residual phases of Chromium exceeded the background value of 40.7 mg kg−1. Adverse effect index revealed a considerably negative effect on benthos occurrence in the mangroves. Values of non-carcinogenic risks were below unity at all samples, whereas the cancer risks associated with Cr(VI) exposure via fish consumption at median were close to 1.73 × 10 − 5 . A sensitivity analysis indicated that sediment Cr(VI) concentration and exposure frequency were the most relevant variables in the risk model. As the first attempt to provide information on the human health risks of sediment Chromium in mangrove forests in China, findings from this study can help track potential adverse effects and avoid risks from sediment Chromium. • Chromium were mainly associated with residual phases. • Total carcinogenic risk of Cr(VI) followed the order of CR fish > CR oral > CR derm. • Cr(VI) concentration and exposure frequency were the most influential parameter in calculating CR fish. [ABSTRACT FROM AUTHOR]

Understanding bioavailable metal behaviour in situ is critical for pollution evaluation and contaminant management in mangrove wetland. Here, the diffusive gradients in thin films technique (DGT) was used for characterizing the (bio)available portions of Cr, Zn, Pb, Cu, Fe and Mn in two mangrove wetlands affected by industrial waste discharges (Jiulong Estuary) and domestic discharges (Zhangjiang Estuary), in Fujian Province, China. In addition, fluorescence excitation emission matrices-parallel factor analysis (EEM-PARAFAC) was applied for characterizing the occurrence and behaviour of dissolved organic matter (DOM) in soil solution, as well as their feasibility for assessing behaviours of metals. The results demonstrated that the combination of DGT and EEM, which are well suitable for studying DOM impacted metal behaviors in mangrove sediments. Discharge of difference wastewater into the mangrove wetlands of Jiulong and Zhangjiang Estuaries, gave rise to the DGT-labile metal concentration of Zn > Cu > Cr > Pb and Zn > Cr > Pb > Cu, respectively. A variety of humic-like fluorescent components was characterized here, providing valuable insights into the chemical composition of DOM in rhizosphere and bulk sediment. Terrestrial humic-like compounds indicated a different binding affinity for heavy metals in mangrove sediments. These findings are useful for the future understanding of the metal speciation and molecular binding mechanisms in such mangrove wetlands. Image 1 • DGT was combined with EEM-PARAFAC method to study metal behaviour. • Humic-like substances were found higher in rhizosphere for metal binding. • Humic substances played a key role in controlling the binding of metals. • Mobility and speciation of metals were related to DOM composition. [ABSTRACT FROM AUTHOR]

• Cu/ZnSOD , FeSOD and MnSOD genes were identified from Kandelia obovata. • KoFSD2 and KoCSD3 were highly expressed in cadmium treated roots. • KoFSD2 overexpression enhance Cd tolerance of the transgenic tobacco plants. Superoxide dismutase (SOD) plays a central function in the antioxidant systems of plants. Expression of SOD family members in plants is reciprocally regulated in response to various abiotic stresses as well as to moderate cadmium (Cd) stress. The mangrove plant, Kandelia obovata , has a high tolerance to Cd. Characterization of mechanisms that control expression of K. obovata SOD (KoSOD) genes in response to heavy metal stress would provide new insight into the physiological and genetic tolerance mechanisms of mangrove plants in contaminated estuaries. Here, seven KoSOD genes belonging to three phylogenetic clusters were identified from K. obovata , as were exon deletions, intron retention, and alternative polyadenylation events that generated diverse KoSOD gene transcripts. Phylogenetic analysis and expression pattern assays in different K. obovata tissues suggested that KoFSD2 and KoCSD3 could be critical for Cd stress responses. Furthermore, KoFSD2 and KoCSD3 overexpressed individually in Nicotiana benthamiana promoted root elongation and higher SOD activity after Cd treatment of transgenic plants relative to wild type plants. The KoFSD2 lines maintained lower O 2 ·− and H 2 O 2 levels under both control and high Cd conditions, whereas KoCSD3 transgenic lines had higher O 2 ·− and H 2 O 2 content in the presence of high Cd. Our findings provide novel insight into reactive oxygen metabolism and genetic mechanisms of K. obovata Cd tolerance in contaminated estuaries. [ABSTRACT FROM AUTHOR]

Abstract Glomalin-related soil protein (GRSP) is a widespread glycoprotein found to have strong ability of sequestering heavy metals in soils. However, the underlying mechanism for metal and metalloid removal as well as water quality improvement and the ecological role played by GRSP are still not well documented. This study was initiated to investigate the interconnection of metal loading in GRSP between sediments and suspended solids, focusing on the mobilization mechanisms of GRSP in the coastal mangrove wetland. Combined indicators of nine heavy metals were significantly positively correlated with GRSP concentration by Principal Component Analysis, indicating that GRSP could act as an indicator of contamination level in the mangrove wetlands. Large distribution of GRSP in sediments and suspended solids elevated sequestration potential of heavy metals (Fe, Mn, Cr, Cu, Zn, Ni, Cd, Pb) and metalloid arsenic in the mangrove aquatic ecosystem. GRSP mobilized and sequestered heavy metals in sediment profiles, which reduced the bioavailability of heavy metals. GRSP was also a significant contributor for suspended solids to adsorb heavy metals, enhancing suspended solids deposition and burial process in sediments. This new finding provided insights into the ecological functions of GRSP and the heavy metal cycling in wetland environments. Graphical abstract Image 1 Highlights • Metals were sequestered by GRSP in mangrove wetlands. • GRSP-bound arsenic was found to be only associated with elevated Fe in GRSP. • GRSP-bound metals were buried in sediments and their mobility was reduced. • GRSP in suspended solids has higher metal sequestration potential than in sediment. • GRSP in suspended solids contributed to heavy metal transport and deposition. [ABSTRACT FROM AUTHOR]

Glomalin-related soil protein (GRSP), a particular terrigenous-derived carbon (C), is transported to the coastal oceans, where it accumulates in sediments. We hypothesized that terrigenous C (GRSP) accumulation could enhance marine C sequestration, and sediment fertility would increase the C stock in the marine ecosystem. In this study, we tested GRSP contribution to marine sediment C, nitrogen (N) and iron (Fe), and explored whether GRSP deposition varied with sediment fertility levels in the Old Yellow River delta. The mean concentration of total GRSP was 1.10 ± 0.04 mg g − 1 (0.24 Mg C ha − 1 ), accounting for 6.41 ± 0.17% of total organic C and 3.75 ± 0.13% of total N in the 0–10 cm marine sediments, indicating that the coastal marine system is an important sink of GRSP. GRSP also contained 1.46 ± 0.06% Fe (20.7 kg Fe ha − 1 ), accounting for 0.058 ± 0.003% of total Fe in marine sediments. Meanwhile, Fe-content in GRSP significantly decreased with distance from the shore, indicating that Fe was released with GRSP transfer and thus GRSP was a new natural Fe fertilization in marine environment. Furthermore, GRSP enhanced marine C sequestration by its rapid deposition and Fe contribution. Combined indicators of sediment fertility (factor 1) were significantly positively correlated with GRSP concentrations by Principal Component Analysis. Co-deposited with nutrient elements, GRSP fractions were accumulated more in more fertile sediments but less in less fertile sediments. GRSP, a mixture of co-existent multiple elements, can be used as a nutrient controlled-release agent in the marine ecosystem. GRSP fractions were responsive to marine sediment fertility levels and the understanding of their function in sediment C sequestration will provide new insights into the importance of terrestrial-marine linkages. [ABSTRACT FROM AUTHOR]

Mangroves are known for sequestering and storing large quantities of phosphorus (P) within their sediments. In the present study, the sediment P cycle (including phosphatase activity intensity, total sedimentary P, P fractions distinguished by a sequential extraction method, as well as diffusion-adsorption processes) in a mangrove swamp in a subtropical estuary in China was studied. In the spring, the acid phosphatase activity varied between 1.3 and 1.9 units in the four sites in the estuary. The activity of alkaline phosphatase varied from 0.8 to 1.4 units. The total sedimentary P ranged from 821 to 1689 mg kg −1 with a dominance of redox-sensitive (Fe/Al bound) P. In the autumn, activities of both phosphatases and the total sediment P amount increased, probably due to enhanced inputs of organic matter and Fe oxides. In addition to seasonal variation, P in the mangrove sediment was influenced by anthropogenic activities. In particular, redox-sensitive P decreased significantly while phosphatase activity increased in the site that was flushed with aquaculture pond effluents. In contrast, sediment P enrichment was observed in the site that received domestic sewage. Both sources of anthropogenic P increased the eutrophication risk of the mangrove sediment because of a decrease in the amount of P adsorption and an enhancement of P release via diffusion. Diesel contamination due to the presence of a dock depressed phosphatase activity in the surficial sediment. The overlap between seasonal rhythm and human influences may introduce significant variations in P cycling, which warrants further attention from coastal management. [ABSTRACT FROM AUTHOR]

Mangrove ecosystems receive substantial polycyclic aromatic hydrocarbons (PAHs) from human activities. The mechanism of transport and translocation of PAHs within mangrove sediment is not well understood. In the present study, the mobility of pyrene in two typical mangrove sediments was studied using soil thin layer chromatography (TLC). The mobility of pyrene in the sediments displayed an inverse trend with organic carbon ( f oc ) content. As one of the important fraction in sediment organic matter pool, the influence of root exudates on adsorption of pyrene within the tested sediments was also evaluated. In particular, root exudates significantly enhanced the bioavailability and mobility of pyrene in the sediments. The effectiveness of root exudates in promotion of pyrene mobility follows an order: citric acid > oxalic acid > malic acid > artificial root exudates (ARE). In addition, mobility factors of pyrene from root exudate treatments were significantly higher than the value determined in the control, and the magnitude of mobility factor (R f ) showed a positive correlation with root exudate concentrations. Results of this study could promote our understanding of the mobility of PAHs in contaminated mangrove sediments. [ABSTRACT FROM AUTHOR]

The uptake and distribution of phenanthrene, a typical polycyclic aromatic hydrocarbon, in plant tissues of Aegiceras corniculatum and Avicennia marina and the relationship with nutrient (nitrate, ammonium, and soluble reactive phosphorus) availability were investigated. After 12 h of exposure, enhancements in the concentration of nitrate and soluble reactive phosphorus markedly decreased the residual level of phenanthrene in roots, while the addition of ammonium significantly increased the residual concentration. Due to the similar enzymatic degradation potential between treatment groups, the variation of phenanthrene concentration in mangrove roots may result from the H+/phenanthrene cotransport at the root surface that was influenced by nutrient uptake. Moreover, both nitrate and soluble reactive phosphorus amendments significantly increased translocation of phenanthrene from roots to leaves, which likely resulted from the change of hydraulic conductivity in mangrove plants triggered by different nutrient availability. [ABSTRACT FROM AUTHOR]

Arbuscular mycorrhizal (AM) fungi produce a recalcitrant glycoprotein, (glomalin-related soil protein (GRSP)), which can contribute to soil carbon sequestration. Here we made a first study to characterize the spatial distribution of GRSP fractions in a mangrove forest at Zhangjiang Estuary, Southeastern China and to explore potential contributions of GRSP to sediment organic carbon (SOC) in this forest. We identified GRSP fractions in surface sediments, as well as those at a depth of 50 cm. The contents of easily extractable GRSP (EE-GRSP), total GRSP (T-GRSP), GRSP in particulate organic matter (POM-GRSP) and GRSP in pore water (PW-GRSP) ranged between 1.20–2.22 mg g − 1 , 1.38–2.61 mg g − 1 , 1.45–10.78 mg g − 1 and 10.35–39.65 mg L − 1 respectively, and these four GRSPs are significantly affected by sample sites and sediment layers. Carbon in GRSP accounted for 2.8–5.9% of SOC and its contributions can far exceed that of microbial biomass carbon (0.21–0.73%) in the 0–50 cm sediment layers. Our data indicate that GRSP could be transported by pore water and accumulated in sediment profiles. The non-linear regression analysis revealed that as SOC and particulate organic carbon (POC) contents decrease, GRSP proportions increase, indicating the increase of the recalcitrant carbon offsetting the effects of mangrove carbon loss, especially labile C. Regression and ordination analyses indicated that GRSP fractions were mainly positively correlated with sediment carbon fractions and spore density but were negatively correlated with sand, pH. Strikingly, the unfavorable environmental factors for microbial organisms, especially AM fungi, prove to be able to promote the production or accumulation of GRSP. We propose that there are two different pathways for affecting the pool size of GRSP in mangrove ecosystems: (i) directly via indigenous AM fungi propagules; (ii) or via the GRSP transport and deposition by pore water and tides. [ABSTRACT FROM AUTHOR]

The oceans are the largest carbon pools on Earth, and play the role of a 'buffer' in climate change. Blue carbon, the carbon (mainly organic carbon) captured by marine ecosystems, is one of the important mechanisms of marine carbon storage. Blue carbon was initially recognized only in the form of visible coastal plant carbon sequestration. In fact, microorganisms (phytoplankton, bacteria, archaea, viruses, and protozoa), which did not receive much attention in the past, account for more than 90% of the total marine biomass and are the main contributors to blue carbon. Chinese coastal seas, equivalent to 1/3 of China's total land area, have a huge carbon sink potential needing urgently research and development. In this paper, we focus on the processes and mechanisms of coastal ocean's carbon sequestration and the approaches for increasing that sequestration. We discuss the structures of coastal ecosystems, the processes of carbon cycle, and the mechanisms of carbon sequestration. Using the evolution of coastal ocean's carbon sinks in sedimentary records over geologic times, we also discuss the possible effects of natural processes and anthropogenic activities on marine carbon sinks. Finally, we discuss the prospect of using carbon sequestration engineering for increasing coastal ocean's carbon storage capacity. [ABSTRACT FROM AUTHOR]

• HBCD inherent in PS MPs greatly promotes the metals' adsorption. • log K MeOH can be used as an indicator parameter for the adsorption affinity. • The –O and –Br groups of HBCD/PS MPs are involved in the metals' adsorption. • HBCD enhances the long-range transfer of the metals via MPs. Microplastics (MPs) are known to act as carriers of heavy metals; however, little is known about the intrinsic chemical additives of MPs, such as hexabromocyclododecane (HBCD), in terms of the adsorption behaviors and migration risks of heavy metals on MPs. Here, we reported the potential mechanisms and risks of HBCD inherent in polystyrene (PS) MPs with Cu(II), Ni(II), and Zn(II) adsorption/desorption. A comparison of the adsorption capacity of the metals onto HBCD/PS composites (HBCD/PS) MPs (10.31–20.76 μmol/g), pure MPs (0–3.60 μmol/g), and natural minerals (0.11–13.88 μmol/g) showed that the addition of HBCD significantly promoted the metals adsorption onto the HBCD/PS MPs, and even exceeded that of natural particles. Isotherms and thermodynamic data suggested that the adsorption process of the metals onto the HBCD/PS MPs was spontaneous and endothermic, and that the adsorption was a mainly multi-ion process with an inclined direction. Furthermore, the results of SEM-EDS, FTIR, and XPS analyses, as well as density functional theory well explained that the metals were mainly adsorbed on the –O and –Br groups of the HBCD/PS MPs via electrostatic interactions and surface complexation. More importantly, by comparing the desorption activity with natural river water and seawater, HBCD inherent in MPs can enhance the long-range transfer of metals carried by the HBCD/PS MPs from contamination sources to potential sink like oceans. Thus, the HBCD/PS MPs with high loading of Cu(II), Ni(II), and Zn(II) could be potential secondary sources of these metals in seawater. Overall, these findings revealed the potential risks of flame retardant in MPs associated with metal migration, and advocated that flame retardant-related waste MPs should be included in coastal sustainable development. [Display omitted] [ABSTRACT FROM AUTHOR]

Phenols exert a great influence on the dynamic process of Cd in the soil-plant interface. We investigated the influence of phenols on the biogeochemical behavior of cadmium in the rhizosphere of Avicennia marina (Forsk) Vierh. All combinations of four levels of cadmium (0, 1, 2 and 4 mg/kg DW) and two levels of phenol (0 and 15 mg/kg DW) were included in the experimental design. We found that phenols facilitated increasing concentrations of exchangeable cadmium (Ex-Cd), acid volatile sulfide (AVS) and reactive solid-phase Fe (II) in sediments, and iron in plants, but inhibited Cd accumulation in iron plaque and roots. The concentrations of AVS and reactive solid-phase Fe (II) were significantly positively correlated with Cd treatment. As for the biogeochemical behavior of Cd in mangrove sediments, this research revealed that phenols facilitated activation and mobility of Cd. They disturbed the “source-sink” balance of Cd and turned it into a “source”, whilst decreasing Cd absorption in A. marina . Additionally, phenols facilitated iron absorption in the plant and alleviated the Fe limit for mangrove plant growth. [ABSTRACT FROM AUTHOR]

In this study, mangrove seedlings (Kandelia obovata(S. L.)) were cultivated in rhizo-boxes, which contain sediments collected from natural mangrove forest and modified with different rates of sulphate and phosphate. The fraction distributions of Zn, Cd, Cu, Ni and Pb in rhizosphere and non-rhizosphere sediments were studied by using a sequential extraction method. Metal concentrations in plant tissues and iron plaque on root surface were also determined to reveal migration variation of heavy metals in the plant-sediment system. The results showed that the activities ofK. obovataroots enhance the reducible metals while reducing acid-extractable and oxidisable metals; sulphur amendment benefits the combination of metal ions with S2–and therefore reduces the bioavailability of metal pollutants; addition of sulphur also improves the content of iron plaque on the root surface, which plays an important role in metal accumulation byK. obovataroot tissue; the addition of sulphur markedly reduces the concentration of Cd in roots, but significantly enhanced the concentrations of Cu, Zn, Ni and Pb in roots. The results indicate that sulphur and phosphorus content in mangrove sediment, and the growth of mangrove plant can significantly influence the migration of heavy metals in the mangrove wetland ecosystem. [ABSTRACT FROM AUTHOR]

[Display omitted] • Disposable face masks (DFMs) can act as carriers of Pb(Ⅱ), Cd(Ⅱ), and Sr(Ⅱ) ions. • Aging enhances the DMFs' adsorption capacity with metals. • Adsorption affinity for DFMs with metals is related to electronegativity of metals. • Salinity and pH both influence the metals' adsorption process. • The adsorption process is dominated by electrostatic and complexation interactions. The demand for disposable face masks (DFMs) increased sharply in response to the COVID-19 pandemic. However, information regarding the underlying roles of the largely discarded DFMs in the environment is extremely lacking. This study focused on the pristine and UV-aged DFMs as vectors of metal ions (Pb(Ⅱ), Cd(Ⅱ), and Sr(Ⅱ)). Further, the aging mechanism of DFMs with UV radiation as well as the interaction mechanisms between DFMs and metal ions were investigated. Results revealed that the aging process would help to promote more metal ions adsorbed onto DFMs, which was mainly attributed to the presence of oxygen-containing groups on the aged DFMs. The adsorption affinity of pristine and aged DFMs for the metal ions followed Pb(Ⅱ) > Cd(Ⅱ) > Sr(Ⅱ), which was positively corrected with the electronegativity of the metals. Interestingly, we found that even if DFMs were not disrupted, DFMs had similar or even higher adsorption affinity for metals compared with other existing microplastics. Besides, regarding environmental factors, including salinity and solution pH played a crucial role in the adsorption processes, with greater adsorption capacities for pristine and aged DFMs at higher pH values and low salinity. Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and density functional theory further confirmed that the pristine DFMs interacted with the metals mainly through electrostatic interaction, while electrostatic interaction and surface complexation jointly regulated the adsorption of the metals onto aged DFMs. Overall, these findings would help to evaluate environmental behaviors and risks of DFMs associated with metals. [ABSTRACT FROM AUTHOR]

Highlights: [•] We studied dual effects of AMF and KH2PO4 supply on the growth and nutrient uptake of K. obovata. [•] AMF inoculation and KH2PO4 supply increased plant biomass, root vitality and P uptake. [•] AMF inoculation alleviated soil ACP and ALP activities reduction caused by KH2PO4 supply. [•] AMF inoculation alleviated P limitation in K. obovata growth. [Copyright &y& Elsevier]

Highlights: [•] Image analysis allowed us to detect the distribution of metals in K. obovata tissue. [•] Cell wall binding was involved in metal tolerance of K. obovata. [•] The root epidermis provided a major barrier to the transport of metals in K. obovata. [•] Metal detoxification was influenced by the sub-cellular fractions. [ABSTRACT FROM AUTHOR]

Mangrove wetlands are subjected to pollution due to anthropogenic activities. Mangrove fitness is mainly determined by root exudates and microorganisms activities belowground, but the mechanisms are not yet well known. Rhizospheric interactions among mangrove sediments, microorganisms and root exudates were simulated. In particular, low-molecular-weight organic acids (LMWOA), were examined to explore the metal(loid)s rhizospheric dynamics via batch experiments. Using a combination of comparative sterilised and unsterilised sediments, LMWOA extracts and sediments constituents were examined. Factors such as the solution pH, dissolved organic carbon (DOC), arsenic and iron species and metal(loid)s in the aqueous phase were evaluated. The results show that on an average, the As decreased by 68.3 % and 42.1 % under citric and malic acid treatments, respectively, after sterilisation. In contrast, the As content increased by 29.6 % under oxalic acid treatment. Microorganisms probably facilitate sediment As release in the presence of citric and malic acids but suppress As mobilisation in the presence of oxalic acid. Fe, Mn and Al were significantly (p < 0.05) positively correlated with the trace metal(loid)s (Zn, Pb, Ni, Cu, Cr, Co, Ba, Cd and As). The solution pH was negatively correlated with the solution As. Both DOC and pH reach the peaks at the end of all treatments. The As absorption–desorption dynamics are closely linked to proton consumption, Fe-Mn-Al sedimentation of ageing performance and organic ligand complexation. The study provides an insight into the rhizospheric processes of microbial involvement and gives an enlightening understanding of the metal(loid)s redeployment for plant adaptation in mangrove wetlands. [Display omitted] • Microbes facilitated As extraction of citric and malic acid positively under laboratory conditions. • Under the action of microorganisms, citric acid from root exudates promotes the release of As in mangrove sediments. • Inorganic As species put a potential exposure risk extracted from sediments via LMWOAs. • Desorption-absorption dynamics of As synchronized with sedimentation and ageing processes of Fe, Mn, and Al via STEM-EDAX. [ABSTRACT FROM AUTHOR]

[Display omitted] • We proposed a new framework based on distinct coastal soil textures. • Coastal soil texture explained variation in C:N:P stoichiometry and SOC storages. • SOC stabilization mechanism was revealed by multiple chemical characterizations. • Glomalin-related soil protein contributed to the stability of mangrove SOC. Mangroves are among the most carbon-rich forests in the tropics, but the spatial variation in soil organic carbon (SOC) storage and the mechanisms controlling their stability remain contentious. Here, we proposed a new framework based on distinct coastal soil textures (muddy, sandy, and mud-sand mixed soil) and found that coastal soil texture exhibits regional-scale variations in mangrove soil C:N:P stoichiometry and SOC storage. Using this soil texture classification framework, we identified the important role of mud-sand mixed soil, which functions as a blue carbon hotspot in coastal wetlands. We showed that mangrove SOC storage was underestimated by approximately 37% in mud-sand mixed soil and overestimated by approximately 54% in muddy soil. We further revealed that the chemical composition of SOC and clay mineralogy are responsible for SOC stability by combining physical and chemical characterizations. As a microbial-derived C, glomalin-related soil protein (GRSP) contained higher alkyl C (∼58%) and lower O-alkyl C (∼17%) than mangrove soils, indicating that GRSP contributes to the stable SOC pool by its recalcitrant structure. We further found that the C:N:P stoichiometric signature of GRSP can capture variations in mangrove SOC storage compatible with distinct coastal soil textures. These results highlight the role of GRSP in regulating SOC stabilization mechanisms, potentially attenuating coastal blue carbon-climate feedback. Regional-scale variation in SOC linked to coastal soil textures can provide more robust estimates of the contribution of mangrove SOC to global C dynamics. [ABSTRACT FROM AUTHOR]

Abstract: A greenhouse experiment was conducted to evaluate degradation gradient of spiked phenanthrene (Ph, 10mgkg−1) and pyrene (Py, 10mgkg−1) in rhizosphere of mangrove Kandelia candel (L.) Druce. Rhizosphere model system was set up using a self-design laminar rhizoboxes which divided into eight separate compartments at various distances from the root surface. After 60 days of plant growth, presence of the plant significantly enhanced the dissipation of Ph (47.7%) and Py (37.6%) from contaminated sediment. Higher degradation rates of the PAHs were observed at 3mm from the root zone (56.8% Ph and 47.7% Py). The degradation gradient followed the order: near rhizosphere>root compartment>far-rhizosphere soil zones for both contaminants where mangrove was grown. Contribution of direct plant uptake and accumulation of Ph and Py were very low compared to the plant enhanced dissipation. By contrast, plant-promoted biodegradation was the predominant contribution to the remediation enhancement. The correlation analysis indicates a negative relation between biological activities (microbial biomass carbon, dehydrogenase, urease, and phosphatase activity) and residual concentrations of Ph and Py in planted soils. Our results suggested that mangrove rhizosphere was effective in promoting the depletion of aromatic hydrocarbons in contaminated sediments. [Copyright &y& Elsevier]

Abstract: Four transects including sixteen stations were established in the Fugong mangrove (117°54′-117°55′E, 24°22′-24°24′N) of the Jiulong River Estuary, Fujian, China. Besides geochemical characterization and estimation of bacterial abundances, the distribution of α- and β-glucosidase activity was studied to explore the degradation of carbohydrates which can be expected to occur in high quantities in mangrove systems. The distribution pattern of microbial α-glucosidase and β-glucosidase activities was investigated using a fluorogenic model substrate (FMS) technique in order to allow better understanding of in situ enzyme activities, as well as their relation to bacterial biomass, metabolic activity and environmental factors in mangrove sediments. The results showed that the enzyme activities of α-glucosidase (10.83~100.86 µmol g-1 h-1) and β-glucosidase (39.60~222.75 µmol g-1 h-1) varied among the different stations, and the enzyme activities of β-glucosidase were higher than those of α-glucosidase at all stations. The extracellular enzyme activities were positively related to organic C, organic matter and bacterial abundance. In addition, the use of the FMS technique to measure extracellular enzyme activities of mangrove sediments could help us to evaluate their catabolic behavior in situ and so lead to a better understanding of the bacterial role in material cycle of mangrove swamp ecosystems. [Copyright &y& Elsevier]

Aquaculture effluent discharge containing heavy metals affects estuarine mangrove wetlands. Glomalin-related soil protein (GRSP) is recalcitrant organic matter that can be trapped in mangrove wetlands and is critical to metal sequestration. However, studies on the effects of long-term aquaculture effluents on metal pollution in adjacent mangrove wetlands and the ecological role of GRSP are lacking. For the first time, we revealed the effects of discharge histories (0, 8, and 14 years) of shrimp pond effluents on metals (As, Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn), including the entire process from feed to metals binding with GRSP in mangrove soils. Results showed that mangrove soils receiving the effluents generally had higher or similar metal loadings compared to the control, and long-term effluent discharge increased the potential toxicity of the metals. Aquaculture feed could be a main source of metal input. Redundancy analysis indicated that 14-year effluent discharge increased the pH, bulk density, total nitrogen, and total phosphorus of mangrove soils, reducing the potential of GRSP-bound metals. Scanning electron microscopy and infrared spectroscopy characterisation revealed that effluent disturbances changed the surface morphology and functional group contents of GRSP. This study provides insights into using GRSP as an aquaculture pollution bioindicator. [Display omitted] • Shrimp pond effluents affected the loading and toxicity of metals in wetlands. • The bioavailable metals increased with increasing effluent discharge histories. • Feed is a main metal pollution source in shrimp ponds and aquatic ecosystems. • The 14-year effluent discharge decreased the contents of GRSP and GRSP-bound metals. • GRSP could be a new indicator of aquaculture disturbance based on SEM and FTIR. [ABSTRACT FROM AUTHOR]

Dissolved organic matter (DOM) can be transported from mangrove wetlands to the ocean, as a key link in the global carbon cycle. The continuum between mangrove creeks and the ocean is a prime location for facilitating reactions between DOM and sunlight or microbes. Yet, little is known about the sources, transformation, and fate of DOM in the transport continuum at the critical land-to-sea zone. Here, water samples were collected in the estuary of southeastern China along mangrove creeks. We found that DOC concentrations ranged from 6.65 to 110.48 mg/L along the creek-to-estuary continuum. The high accumulation of DOC can be due to the high residence time of seawater and more sensitivity to environmental disturbance. 1.75 times higher DOC concentrations were showed in the lower area than the upper area of the transporting continuum. DOM materials in mangrove creeks were characterized by mostly labile, highly degradable proteins. Terrestrial index (TI) and marine-derived index (MI) were respectively used to described allochthonous and autochthonous characteristics of DOM. The DOM showed a high TI and low MI in the upper area and low TI and high MI in the lower area of outputting continuum. DOM quality along the mangrove to estuary continuum corresponded with environmental heterogeneity. Biodegradation and photo-biodegradation experiments were conducted on DOM samples over 20-days. A rapid 40–65% decrease was observed in DOC concentration in response to biodegradation. About 45% decrease of DOC concentration in photodegradation, afterward less loss in photo-biodegradation than was examined with biodegradation alone. Chromophoric dissolved organic matter (CDOM) concentrations of the continuum were in fluctuating changes during biodegradation. CDOM was preferentially removed 60–90% then increased significantly in photo-biodegradation. Photo-mediated protein-like substances were demonstrated in strong reactions during biodegradation. Compared to biodegradation alone, DOM quality can be distinctly altered during photo-biodegradation. This study demonstrates that DOM quality was gradually homogenized due to interaction with sunlight and microbes during transport from the mangrove creek to the ocean. [Display omitted] • DOC concentrations range in the threshold regulated by sunlight and microbes. • Photo-altered or highly bioavailable CDOM can be pooled from mangroves to estuary. • DOC, CDOM and FDOM were degraded in similar rules yet distinct levels. • Photo-biodegradation altered DOM much more effectively than biodegradation. • DOM quality was homogenized by sunlight and microbes from mangroves to estuary. [ABSTRACT FROM AUTHOR]

Summary: The Sec14 protein (Sec14p) and its homologs are involved in the transfer of phosphatidylinositol/phosphatidylcholine phospholipids in eukaryotic cells. In the completely sequenced genome of Arabidopsis thaliana, multiple genes encoding putative Sec14p homologs have been predicted based on bioinformatic analysis. Here we report the identification of two yeast Sec14-like genes (designated as AtSFH3 and AtSFH12, respectively) that are predominately transcribed in Arabidopsis flowers. The deduced amino acid sequences of AtSfh3p and AtSfh12p exhibited high similarity to that of Sec14p. Ectopic expression of AtSfh3p or AtSfh12p corrected the high temperature sensitive phenotype caused by Sec14p functional deficiency in Saccharomyces cerevisiae, indicating that the two plant homologs are functional in the intracellular environment. AtSFH3 transcripts were detected in flowers, stems and immature siliques but not roots and leaves, with a relatively higher transcript level in the flowers. In contrast, AtSFH12 transcripts were only detectable in the flowers. Based on histochemical staining of β-glucuronidase (GUS) activities in the transgenic Arabidopsis plants harboring promoter∷GUS constructs, AtSFH3 transcription was first detected in the stigma papillae of the flowers at stage 11, and then in the pollen grains before and after fertilization. On the other hand, AtSFH12 transcription was only found in the mature and germinating pollen grains. The information from this study may provide useful clue for further analysis of the function of plant Sec14p homologs in the development of the male gametic cells and/or the fertilization process in higher plants. [Copyright &y& Elsevier]

Articulated fossil brachiopod shells have been used extensively to extract primary chemical information of Phanerozoic seawater. Despite the selection of well-preserved shells using trace element, microstructure and cathodoluminescence criteria, there are still concerns as to whether the selected brachiopod shells do indeed contain original seawater signals. Analyzed in-situ by Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry (LAICPMS), Sr, Na, Mg, Mn, B and Ba distribute symmetrically in shell transects of the modern brachiopods Magellania flavescens and Terebratulina septentrionalis. Symmetry of the trace element distribution pattern is considered an intrinsic and original ontogenetic property of the brachiopod shell chemistry. The trace element distribution is symmetrical in a well-preserved shell of the Devonian brachiopod Independatrypa lemma, indicating that the selected shell by the conventional criteria has preserved its original seawater signal for 400 Ma. In another specimen of I. lemma that is considered diagenetically altered, trace element concentrations are asymmetrically distributed in the shell. The agreement between the distribution criteria and the conventional methods indicates the latter can be used to select brachiopod shells with original seawater chemistry. The average element concentration in the whole shell of unaltered brachiopods should be a reflection of the seawater chemistry, while its change in different part of a shell reflects ontogenetic effect, and its high frequent fluctuations in a transect are results of changes in environmental parameters with seasonal or annual characteristics. [Copyright &y& Elsevier]

• Ancient river management created a 12.4 × 103 km2 area with elevated heavy metals. • Geographical factors related to previous estuary determine the pattern of Cd/Zn. • Rare taxa determined the prokaryotic diversity under the influence of heavy metals. • "Overlapping micro-niche" model could explain the increasing prokaryotic diversity. River management, both modern and historical, have dramatically modified offshore environments. While numerous studies have described the modern impacts, very few have evaluated the legacies remaining from hundreds of years ago. Herein, we show trace metal enrichment in the surface sediment of the abandoned Yellow River Delta, hypothesized to be associated with ancient river management. Essentially, anthropogenic modification caused the river to shift, creating a 12.4×103 km2 area with elevated trace metals; characterized by clear metal deposition gradients. Geographical factors related to the ancient river mouth had the most significant influences on Zn (explained by distance to the river mouth, DTM) and Cd (DTM and sediment salinity), while the sediment absorptive capacity was associated with the reallocation of Cu (clay, silt, and iron), Ni (clay and iron), and Pb (silt and iron). Trace metal legacies showed stronger influences on prokaryotic diversity than on micro-eukaryotic diversity, with the former best described by changes in rare, rather than dominant families and classes, and explainable by an "overlapping micro-niche" model. The ancient river's legacies provide evidence of longer-term human disturbance over hundreds of years; as its impacts on associated benthic microbiomes have led to lessons for modern-day waterway management of benthic ecosystems. [ABSTRACT FROM AUTHOR]