Effects of Biochar on Plant Growth and Cadmium Uptake: Case Studies on Asian Lotus (Nelumbo nucifera) and Chinese Sage (Salvia miltiorrhiza)

Application of biochar has many benefits in agriculture, to understand benefits of biochar in crop production and remediation of heavy metal pollution, Asian lotus (Nelumbo nucifera) as an aquatic crop and Chinese sage (Salvia miltiorrhiza) as a traditional medicinal herb were used to evaluate biochar’s effects on plant growth and cadmium (Cd) accumulation in plants in the artificially Cd-polluted condition in containers. In both cases, adding biochar (4% to 32% in soil mix) significantly increased plant biomass. However, its impact on plant physiological traits were unclear. In Asian lotus, the Cd content in rhizomes, petioles, and leaves significantly increased by 69%, 81% and 55%, respectively as 32% biochar added. Meanwhile, a maximum reduction (71%) showed on bioaccumulation coefficient of Cd, and an up to 1.3 folds increase occurred on Cd transfer coefficient of underground to aboveground tissues, which indicated that biochar effectively prevented Cd uptake in major edible parts. In Chinese sage, adding 32% biochar significantly decreased Cd content in leaves and roots by 52.81% and 43.63%, respectively. Therefore, as a valuable soil amendment of improving plant growth and reducing heavy metal uptake, biochar has a huge potential in green agriculture production and remediation of heavy-metal polluted environment

Tracing and trapping micro- and nanoplastics: untapped mitigation potential of aquatic plants?

Micro- and nanoplastics are emerging concerns due to their environmental ubiquity and currently largely unknown ecological impacts. Leveraging on a recently developed method using europium-doped polystyrene particles (PS-Eu), our present work aimed to accurately trace the uptake and transport of micro- and nanoplastics in aquatic plants and shed insights into the potential of different aquatic plants for trapping and removal of plastics from water environment. Seedlings of Vallisneria denseserrulata Makino (submerged plant), Iris tectorum Maxim (emergent plant), and Eichhornia crassipes Solms (floating plant) were exposed to 100 nm and 2 μm PS-Eu in freshwater (5 μg/mL) or sediments (5 μg/g) for 8 weeks. Fluorescence imaging clearly evidenced that PS-Eu mainly accumulated in the intercellular space and were transported from roots to leaves via the apoplastic path and vascular bundle. Mass spectrum analysis demonstrated that up to 6250 μg/g nanoplastics were trapped in aquatic plants (mainly in roots) with a bioconcentration factor of 306.5, depending on exposure routes and plant species. Owing to their excellent capture capability and high tolerance to plastic exposures, floating plants like E. crassipes are promising for immobilizing and removing fine plastics from the water environment.Environmental Biolog

Spatial and Seasonal Patterns of Nutrients and Heavy Metals in Twenty-Seven Rivers Draining into the South China Sea

Due to the acceleration of industrialization and urbanization in recent decades, the majority of coastal rivers and estuaries in China have been moderately or severely contaminated by a variety of pollutants. We investigated the spatial and seasonal variations of water nutrients (permanganate index, chemical oxygen demand, biochemical oxygen demand, ammonium, nitrate, total nitrogen, and total phosphorus) and heavy metals (Hg, Pb, Cu, Zn, Se, As, Cd, Cr, Fe, and Mn) in 27 subtropical rivers draining into the South China Sea. Our results indicated that the average concentrations of all water quality parameters except ammonium, total nitrogen, and total phosphorus satisfied the requirements for grade III of the surface water quality standard of China. The concentrations of both nutrients and heavy metals showed a strong spatial variation. Cluster analysis classified the 27 rivers into three spatial clusters corresponding to low, moderate, and high pollution levels. In terms of seasonal variation, the values of chemical oxygen demand and biochemical oxygen demand in wet seasons were significantly lower than those in dry seasons. Multivariate statistical analyses demonstrated that river nutrients might mainly originate from domestic, industrial, and agricultural wastewaters, while heavy metals likely came from industrial activities and natural weathering processes. The findings of this study suggest that for reducing the pollution of subtropical rivers draining into the South China Sea, further efforts should be made to control nitrogen and phosphorus export from catchments

A Comparative Study on the Uptake of Polycyclic Aromatic Hydrocarbons by Anodonta Californiensis

Uptake of polycyclic aromatic hydrocarbons (PAHs) by the freshwater bivalve mollusc Anodonta californiensis was examined in the presence and absence of surfactant in order to gain further insight into mixture toxicity and to predict whether certain mixtures have negative and/or positive effects on aquatic organisms. In the presence of surfactant, the uptake of anthracene or chrysene was higher than that of naphthalene, given the same concentration in the solution. In the absence of surfactant, the trend was similar, but the uptakes were increased by approximately 100% compared to those in the presence of surfactant. On the uptake of naphthalene, the presence of anthracene showed only minor influence. The uptake of anthracene was affected by both naphthalene and chrysene. The uptake of chrysene was influenced by neither naphthalene nor anthracene. There was no observable displacement of divalent cations from the surface of the gill membrane by any of the PAHs studied

Spatial and Seasonal Dynamics of Water Quality, Sediment Properties and Submerged Vegetation in a Eutrophic Lake after Ten Years of Ecological Restoration

Eutrophication has caused many serious environmental issues in lakes. Submerged vegetation, which plays a key role in maintaining the clear water state of shallow lakes, is strongly influenced by water quality and sediment properties. In this study, we seasonally investigated the water quality, sediment properties and submerged plant communities in 18 sites in Lake Honghu of China, an internationally important wetland under the Ramsar Convention. Results indicated that most of the water quality parameters and sediment properties showed no significant difference among the three site types (i.e., perennially vegetated, seasonally vegetated and unvegetated). However, the Secchi depth in perennially and seasonally vegetated sites was significantly higher that in unvegetated sites. By contrast, season had a strong effect on most of the water quality parameters and sediment properties (e.g., water chlorophyll-a concentration). For submerged vegetation, species richness and biomass showed significant spatial but not seasonal differences, with higher richness and biomass in perennially vegetated sites. Canonical correspondence analysis indicated that the distribution of submerged plants was mainly determined by water NH4+ concentration and water depth. Our findings suggest that restoration of submerged vegetation in Chinese eutrophic lakes may be a feasible method for improving water environments and enhancing ecological functions

ELMOD3-Rab1A-Flotillin2 cascade regulates lumen formation via vesicle trafficking in Ciona notochord

Lumen development is a crucial phase in tubulogenesis, although its molecular mechanisms are largely unknown. In this study, we discovered an ELMO domain-containing 3 (ELMOD3), which belongs to ADP-ribosylation factor GTPase-activating protein family, was necessary to form the notochord lumen in Ciona larvae. We demonstrated that ELMOD3 interacted with lipid raft protein Flotillin2 and regulated its subcellular localization. The loss-of-function of Flotillin2 prevented notochord lumen formation. Furthermore, we found that ELMOD3 also interacted with Rab1A, which is the regulatory GTPase for vesicle trafficking and located at the notochord cell surface. Rab1A mutations arrested the lumen formation, phenocopying the loss-of-function of ELMOD3 and Flotillin2. Our findings further suggested that Rab1A interactions influenced Flotillin2 localization. We thus identified a unique pathway in which ELMOD3 interacted with Rab1A, which controlled the Flotillin2-mediated vesicle trafficking from cytoplasm to apical membrane, required for Ciona notochord lumen formation

Soil aggregate-associated heavy metals subjected to different types of land use in subtropical China

Heavy metal distribution in soils is strongly influenced by soil aggregate size. In this study, we collected surface soil samples from farmlands (FL), woodlands (WL), and bare lands (BL). Air-dried soils were sieved into four size fractions (>3, 1-3, 0.25-1, and 0.25 mm) was significantly higher than that of microaggregates (3 mm) showed an order of FL > ML > BL, while the proportion of microaggregates (<0.25 mm) showed an order of FL < ML < BL. The soil Cd and Pb levels in woodlands were significantly higher than those in farmlands and bare lands. In addition, the concentrations of soil Cu and Zn were elevated in farmlands compared to woodlands and bare lands. For the aggregate-associated heavy metal, contents of most metal elements (except As) in soil aggregates slightly decreased with increasing size class in farmlands. Heavy metals were generally depleted in the larger aggregates but enriched in the smaller aggregates. Interestingly, soil organic matter content was positively related to soil Cd, Cr, Ni, and Pb concentrations, but negatively correlated with soil Cu and As levels. The findings suggest that land use changes can affect the concentrations of soil aggregate-associated heavy metals, and these effects vary among different metals. (C) 2018 The Authors. Published by Elsevier B.V

Synthesis, crystal structure, and characterization of Na2SrV4O12: A low‐firing dielectric vanadate

In this work, cyclotetravanadate Na2SrV4O12 was synthesized at a relatively low sintering temperature of ∼ 500 ° C using a solid-state reaction method. X-ray diffraction and transmission electron microscope characterization featured a tetragonal structure that was built by a 3D frame of isolated tetracyclic (V4O12)4−. Dielectric measurements demonstrated strong dependence on frequency and temperature. A low relative permittivity of εr ∼ 8 ± 0.2 and a dielectric (loss tanδ) ∼ 0.4 ± 0.01 was achieved at a frequency of 10 kHz and room temperature. ac impedance and conductivity analysis revealed a thermally activated migration behavior of charge carriers with a short-range hopping feature. XPS analysis validated the existence of oxygen vacancy and reduction in vanadium (from V5+ to V4+), which gave rise to charged lattice defects. The migration or hopping of such charged defects was responsible for the observed electrical behaviors. Owing to the simple composition, inexpensive raw materials, and low density (2.99 g/cm3) make Na2SrV4O12 ceramic a potential candidate for lightweight devices and in photocatalytic degradation and all-solid-state ion batteries