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In this study, soil samples were collected to a depth of 100 cm from different land-uses, including maize field (MZ), wheat field (WT), paddy field (PD), apple orchard (OC), grassland (GL) and wetland (WL) in the Ili River Valley in northwest China, to investigate the effects of land-use on vertical distributions of soil carbon (C) and nitrogen (N) fractions, and examine whether such effects were different between topsoil (0–40 cm) and subsoil (40–100 cm). The results showed that soil organic C, water-extractable organic C, microbial biomass C, total N and microbial biomass N of croplands (MZ, WT, PD and OC) were significantly lower than those of natural lands (GL and WL) in both topsoil and subsoil, indicating that contents of soil C and N fractions can be reduced by agricultural land-uses, and the reductions are not limited to topsoil. However, the contents of soil ammonium N and nitrate N showed complex trends under different land-uses, possibly due to that the plant species and agricultural practices (e.g. application rate of fertiliser and irrigation) are considerably different among land-uses. Therefore, we suggest that more nutrient inputs should be applied to croplands to improve soil fertility in the Ili River Valley. [ABSTRACT FROM AUTHOR]

Bosten Lake, the largest inland lake in China, has been contaminated with arsenic (As) due to anthropogenic activities. Salinity of the lake water has been increasing due to the extremely dry climate and salt drainage from the farmland. Effects of the increasing salinity on the geochemical behavior of arsenic in sediment are still unclear. In this study, vertical variation of geochemical fractions of As in sediment and arsenic concentration in porewater along the salinity gradient of Bosten Lake was studied. Effects of salinity and ions and anions in porewater on arsenic concentration were also examined. Arsenic content in the five Tessier fractions followed the decreasing order of residual ≫ exchangeable > Fe and Mn oxides > organic > carbonate. The ecological risk of arsenic in the sediment was at low or medium levels, indicated by the low percentage of exchangeable and carbonate bound fractions. Contrary to the decreasing electrical conductivity of porewater with depth, arsenic concentration in porewater showed an increasing trend with depth. Arsenic concentration in porewater increased from around zero at the surface layer of sediment to over 600 μg L in deeper layers of some sites. Arsenic concentration inversely correlated with electrical conductivity in porewater. Arsenic concentration generally decreased with increasing concentrations of SO, Ca, Mg and Na but showed no clear relation with concentrations of K and Cl. This study implies that increase of salinity may decrease the release of arsenic from sediment and its ecological risk. [ABSTRACT FROM AUTHOR]

Highlights: [ • ] Core–shell structured nanocomposite was designed for Hg(II) sensing and removal. [•] The emission of the nanocomposite showed “Off-On” effect towards Hg(II). [•] It owned high sensitivity, good selectivity and fast response towards Hg(II). [•] It was recyclable for practical application. [ABSTRACT FROM AUTHOR]

Root exudates are considered to have an important role in mobility and bioavailability of heavy metals. High molecular weight (HMW) substances are the main components of root exudates, however, knowledge about their interactions with heavy metals is lacking. In the present study, Pb(II) complexation of the HMW fluorescent fractions in root exudates from Salicornia europaea L. was investigated using excitation emission matrix (EEM) fluorescence spectroscopy. Two protein-like fluorescence peaks were identified in the EEM spectrum of root exudates. The fluorescence of both peaks was clearly quenched by Pb(II). The values of conditional stability constants, log Ka, for these two protein-like fluorescence peaks were 4.14 and 3.79. This indicates that the fluorescent substances are strong Pb(II) complexing organic ligands. [ABSTRACT FROM AUTHOR]

In this study, Alhagisparsifolia Shap. was used to test the hypothesis that leaf economic and hydraulic traits are coupled in plants in a hyper-arid region. Five economic traits and six hydraulic traits were examined to explore the relationship. Results showed that the stomatal density (SD) on both surfaces was coupled with maximum stomatal conductance to water vapor (gwmax) and leaf tissue density (TD). SD on adaxial surface (SDaba) was significantly positively related to vein density (VD) but negatively related to leaf thickness (LT) and stomatal length on adaxial surface (SLada). Nitrogen concentration based on mass (Nmass) was significantly negatively correlated with leaf mass per area (LMA), LT, and VD, whereas nitrogen concentration based on area (Narea) was significantly positively related to LMA and TD. Mean annual precipitation (MAP) contributed the most to the changes in LT and stomatal length (SL). Soil salt contributed the most to TD, SD, and gwmax. Soli nutrients influenced the most of LMA and VD. Mean annual temperature contributed the most to Nmass and Narea. In conclusion, the economics of leaves coupled with their hydraulic traits provides an economical and efficient strategy to adapt to the harsh environment in hyper-arid regions. [ABSTRACT FROM AUTHOR]

Background The halophyte Suaeda aralocaspica performs complete C4 photosynthesis within individual cells (SCC4), which is distinct from typical C4 plants, which require the collaboration of 2 types of photosynthetic cells. However, despite SCC4 plants having features that are valuable in engineering higher photosynthetic efficiencies in agriculturally important C3 species such as rice, there are no reported sequenced SCC4 plant genomes, limiting our understanding of the mechanisms involved in, and evolution of, SCC4 photosynthesis. Findings Using Illumina and Pacific Biosciences sequencing platforms, we generated ∼202 Gb of clean genomic DNA sequences having a 433-fold coverage based on the 467 Mb estimated genome size of S. aralocaspica. The final genome assembly was 452 Mb, consisting of 4,033 scaffolds, with a scaffold N50 length of 1.83 Mb. We annotated 29,604 protein-coding genes using Evidence Modeler based on the gene information from ab initio predictions, homology levels with known genes, and RNA sequencing–based transcriptome evidence. We also annotated noncoding genes, including 1,651 long noncoding RNAs, 21 microRNAs, 382 transfer RNAs, 88 small nuclear RNAs, and 325 ribosomal RNAs. A complete (circular with no gaps) chloroplast genome of S. aralocaspica 146,654 bp in length was also assembled. Conclusions We have presented the genome sequence of the SCC4 plant S. aralocaspica. Knowledge of the genome of S. aralocaspica should increase our understanding of the evolution of SCC4 photosynthesis and contribute to the engineering of C4 photosynthesis into economically important C3 crops. [ABSTRACT FROM AUTHOR]

Based on water sampling of the upper reaches of the Syr River and its tributaries from the parts of Aral Sea Basin in Kyrgyzstan, the chemical compositions of river waters were systematically analyzed for revealing the hydrochemical characteristics and evaluating the water quality. Research indicates that there are some differences in ion concentration between the low-flow season (LFS) and high-flow season (HFS), but the hydrochemical classification reflected that all water samples fall in the calcium bicarbonate category, except that only three samples fall in the not dominant category during the LFS. The water quality classification shows that the water samples fall in the excellent to good categories for irrigation use. The analysis shows that the main ions of river waters come from the weathering of rocks, and the dissolution of carbonates is higher than that of silicates. Human activities have had an impact on the waterbody, especially inferred from the indicators of NH4-N and fecal coliform (FC). FC groups were detected in some rivers, in which the detection rate at the high-water level increased. The contents of potentially toxic elements are lower than international drinking water standards, but there are clustering differences between the LFS and HFS. There may be anthropogenic intrusions of Cu, Pb, and Zn during the LFS period and of Cu, Pb, Zn, and Cd during the HFS period. The results fill the gaps in the study of the hydrochemical composition and water quality assessment in the Aral Sea Basin and will also provide a basis for water resource management and for the study of water quality evolution in the future. [ABSTRACT FROM AUTHOR]

The exploitation of a new adsorbent with a high adsorption performance and recyclability is of great practical significance for the treatment of wastewater containing mercury ions. In this study, a novel membrane adsorbent was fabricated by blending MoS 2 nanosheets into a PVDF polymer matrix (P-PVDF/MoS 2 ) followed by non-solvent-induced phase conversion. This material was able to bind mercury ions and was not affected by the solution ionic strength, co-existing anions, or interfering heavy metal ions. The optimal pH range for mercury ion elimination was 4.5-6.0, and P-PVDF/MoS 2 exhibited a maximum adsorption capacity of 578 mg g -1 . The pseudo-second-order adsorption kinetics and Langmuir isotherm models best described the adsorption process. The adsorption mechanism was mainly monolayer chemisorption, for which the S groups were the major active sites. Furthermore, the membrane could be removed from the aqueous solution easily using tweezers, and the removal efficiency of mercury ions remained over 90% after ten cycles. This study suggests that the inexpensive and recyclable P-PVDF/MoS 2 membranes can be used for the efficient removal of heavy metal ions from wastewater at a large scale., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)