The contributions of individual countries and regions to the global radiative forcing.

Knowing the historical relative contribution of greenhouse gases (GHGs) and short-lived climate forcers (SLCFs) to global radiative forcing (RF) at the regional level can help understand how future GHGs emission reductions and associated or independent reductions in SLCFs will affect the ultimate purpose of the Paris Agreement. In this study, we use a compact Earth system model to quantify the global RF and attribute global RF to individual countries and regions. As our evaluation, the United States, the first 15 European Union members, and China are the top three contributors, accounting for 21.9 ± 3.1%, 13.7 ± 1.6%, and 8.6 ± 7.0% of global RF in 2014, respectively. We also find a contrast between developed countries where GHGs dominate the RF and developing countries where SLCFs including aerosols and ozone are more dominant. In developing countries, negative RF caused by aerosols largely masks the positive RF from GHGs. As developing countries take measures to improve the air quality, their negative contributions from aerosols will likely be reduced in the future, which will in turn enhance global warming. This underlines the importance of reducing GHG emissions in parallel to avoid any detrimental consequences from air quality policies.

Pseudomonas guangdongensis sp. nov., isolated from an electroactive biofilm, and emended description of the genus Pseudomonas Migula 1894.

A Gram-negative, straight to slightly curved rod-shaped bacterium, motile with peritrichous flagella, designated SgZ-6(T), was isolated from an electroactive biofilm and was characterized by means of a polyphasic approach. Growth occurred with 0-5.0 % (w/v) NaCl (optimum 1 %), at pH 6.0-10.0 (optimum pH 7.0) and at 10-42 °C (optimum 30 °C) in trypticase soya broth. Phylogenetic analyses based on the 16S rRNA and gyrB genes identified the isolate as a member of a novel species of the genus Pseudomonas. Strain SgZ-6(T) exhibited the highest 16S rRNA gene sequence similarity to 'Pseudomonas linyingensis' CGMCC 1.10701 (97.5 %), followed by Pseudomonas sagittaria JCM 18195(T) (97.4 %), P. oleovorans subsp. lubricantis DSM 21016(T) (96.6 %), P. tuomuerensis JCM 14085(T) (96.5 %) and P. alcaliphila JCM 10630(T) (96.4 %). Strain SgZ-6(T) showed the highest gyrB gene sequence similarity of 93.7 % to 'P. linyingensis' CGMCC 1.10701 among all type strains of genus Pseudomonas. DNA-DNA pairing studies showed that strain SgZ-6(T) displayed 47.1 and 40.3 % relatedness to 'P. linyingensis' CGMCC 1.10701 and P. sagittaria JCM 18195(T), respectively. The major isoprenoid quinone was ubiquinone 9 (Q-9). The whole-cell fatty acids consisted mainly of summed feature 3 (C16 : 1ω6c and/or C16 : 1ω7c), C16 : 0 and summed feature 8 (C18 : 1ω6c and/or C18 : 1ω7c). The DNA G+C content of the genomic DNA was 68.1 mol%. On the basis of phenotypic, chemotaxonomic and phylogenetic data, strain SgZ-6(T) is proposed to represent a novel species of the genus Pseudomonas, for which the name Pseudomonas guangdongensis sp. nov. is proposed. The type strain is SgZ-6(T) ( = CCTCC AB 2012022(T) = KACC 16606(T)). An emended description of the genus Pseudomonas is also proposed.

Azospirillum humicireducens sp. nov., a nitrogen-fixing bacterium isolated from a microbial fuel cell.

A Gram-negative, facultative anaerobic, motile, spiral, straight-to-slightly curved rod-shaped and nitrogen-fixing strain, designated SgZ-5(T), was isolated from a microbial fuel cell (MFC) and was characterized by means of a polyphasic approach. Growth occurred with 0-1 % (w/v) NaCl (optimum 1 %) and at pH 5.5-8.5 (optimum pH 7.2) and at 25-37 °C (optimum 30 °C) in nutrient broth (NB). The strain had the ability to grow under anaerobic conditions via the oxidation of various organic compounds coupled to the reduction of anthraquione-2,6-disulfonate (AQDS). Chemotaxonomic characteristics (main ubiquinone Q-10, major fatty acid C18 : 1ω7c/C18 : 1ω6c and DNA G+C content 67.7 mol%) were similar to those of members of the genus Azospirillum. According to the results of phylogenetic analyses, strain SgZ-5(T) belonged to the genus Azospirillum within the family Rhodospirillaceae of the class Alphaproteobacteria, and was related most closely to the type strains of Azospirillum lipoferum, Azospirillum thiophilum and Azospirillum oryzae (98.0, 97.6 and 97.1 % 16S rRNA gene sequence similarity, respectively). DNA-DNA pairing studies showed that the unidentified organism displayed reassociation values of 36.7 ± 3.7, 24.1 ± 2.2 and 22.3 ± 2.4 % to the type strains of A. lipoferum, A. thiophilum and A. oryzae, respectively. Similarities between nifH gene sequences of strain SgZ-5(T) and members of the genus Azospirillum ranged from 94.0 to 97.0 %. A combination of phenotypic, chemotaxonomic, phylogenetic and genotypic data clearly indicated that strain SgZ-5(T) represents a novel species, for which the name Azospirillum humicireducens sp. nov. is proposed. The type strain is SgZ-5(T) ( = CCTCC AB 2012021(T) = KACC 16605(T)).

Bacillus thermocopriae sp. nov., isolated from a compost.

A Gram-reaction-positive, facultatively anaerobic, motile, endospore-forming, rod-shaped strain, designated SgZ-7(T), was isolated from a windrow compost pile and was characterized by means of a polyphasic approach. Growth occurred with 0-3 % (w/v) NaCl (optimum 1 %), at pH 6.0-10.0 (optimum pH 7.2) and at 40-60 °C (optimum 50 °C). The main respiratory quinone was MK-7. The predominant polar lipids were phosphatidylethanolamine, phosphatidylglycerol and diphosphatidylglycerol. The major fatty acids were iso-C15 : 0 and anteiso-C15 : 0. The DNA G+C content was 46.6 mol%. The phylogenetic analysis based on 16S rRNA gene sequence comparisons revealed that strain SgZ-7(T) should be assigned to the genus Bacillus and was related most closely to Bacillus drentensis LMG 21831(T) (sequence similarity 97.2 %). The result of the DNA-DNA hybridization experiment revealed a low relatedness (27.2 %) between the isolate and B. drentensis LMG 21831(T). The results of phenotypic, chemotaxonomic and genotypic analyses clearly indicated that strain SgZ-7(T) represents a novel species, for which the name Bacillus thermocopriae sp. nov. is proposed. The type strain is SgZ-7(T) (= CCTCC AB 2012030(T) = KACC 16700(T)).

Thauera humireducens sp. nov., a humus-reducing bacterium isolated from a microbial fuel cell.

A Gram-negative, rod-shaped, non-spore-forming bacterium, designated SgZ-1(T), was isolated from the anode biofilm of a microbial fuel cell. The strain had the ability to grow under anaerobic condition via the oxidation of various organic compounds coupled to the reduction of anthraquione-2,6-disulfonate (AQDS) to anthrahydroquinone-2,6-disulfonate (AHQDS). Growth occurred in TSB in the presence of 0-5.5 % (w/v) NaCl (optimum 0-1 %), at 10-45 °C (optimum 25-37 °C) and at pH 6.0-10.0 (optimum 8.0-8.5). Based on 16S rRNA gene sequence similarity, strain SgZ-1(T) belonged to the genus Thauera. The highest level of 16S rRNA gene sequences similarity (96.7 %) was found to be with Thauera aminoaromatica S2(T) and Thauera selenatis AX(T), and lower values were obtained when compared with other recognized Thauera species. Chemotaxonomic analysis revealed that strain SgZ-1(T) contained Q-8 as the predominant quinone, and putrescine and 2-hydroxyputrescine as the major polyamines. The major cellular fatty acids (>5 %) were C16 : 1ω6c and/or C16 : 1ω7c (44.6 %), C16 : 0 (18.8 %), and C18 : 1ω6c and/or C18 : 1ω7c (12.7 %). Based on its phenotypic and phylogenetic properties, chemotaxonomic analysis and the results of physiological and biochemical tests, strain SgZ-1(T) ( = KACC 16524(T) = CCTCC M 2011497(T)) was designated the type strain of a novel species of the genus Thauera, for which the name Thauera humireducens sp. nov. was proposed.

Bioaccumulation and emission of organophosphate esters in plants affecting the atmosphere's phosphorus cycle.

The imbalance of atmospheric, terrestrial and aquatic phosphorus budgets remains a research conundrum and global concern. In this work, the uptake, distribution, bioaccumulation and emission of organophosphate esters (OPEs) by clove trees (Syzygium aromaticum), lemon trees (Citrus limon) and cape jasmine trees (Gardenia jasminoides var. fortuniana) was investigated as conduits for phosphorus transfer or sinks and sources. The objective was to assess the role OPEs in soils play as atmospheric phosphorus sources through plant bioaccumulation and emission. Results demonstrated OPEs in experimental soil plots ranging from 0.01 to 81.0 ng g-1 dry weight, were absorbed and transported through plants to the atmosphere. The total emission of OPEs varied greatly from 0.2 to 588.9 pg g-1 L-1 h-1, with a mean of 47.6 pg g-1 L-1 h-1. There was a negative linear relationship between the concentrations of total phosphorus and four OPEs, tri-iso-butyl phosphate, tri-n-butyl phosphate, tris (2-chloroisopropyl) phosphate and tripentyl phosphate. Trimethyl phosphate levels were positively correlated with total nitrogen, and the concentrations of tri-iso-butyl phosphate, tri-n-butyl phosphate, tris (2-chloroisopropyl) phosphate and tripentyl phosphate decreased along with available potassium in leaves after 72 h. There was a significantly positive linear relationship between higher emission concentrations of OPEs and the emission factor of OPEs concentration (F = 4.2, P = 0.002), with lower emissions of OPEs and the bioaccumulation of OPEs in leaves (F = 4.8, P = 0.004). OPEs releases to the atmosphere were enriched in aerosols, and participate in atmospheric chemical reactions like photolysis, thereby affecting the phosphorus balance and cycling in the atmosphere.

Source identification of particulate phosphorus in the atmosphere in Beijing.

We tracked atmospheric phosphorus (P) in suspended particulate matter (PM) from a site in Beijing, China over a three-year period and found a new relationship between plants and atmospheric P. Concentrations of total phosphorus (TP) in the atmosphere during plant growing seasons were 2.5 times those observed in other months and levels of organic phosphorus (OP) were 3.9 times as high. TP and OP increases during growing seasons were much more significant in PM with diameters of over 2.5 µm (PM>2.5). PM collected during growing seasons included high levels of P but less nitrogen than that in primary biogenic aerosol particles (PBAPs) and differed from other emission sources such as combustion emissions and dust. A time series of OP concentrations in the atmosphere shows a time lag relative to Normalized Difference Vegetation Index (NDVI) data with high levels found during early growing periods and much lower levels found during flourishing periods. Thus, we find that plants contribute to atmospheric P and especially to OP rather than to PBAP levels.

Graphene oxide-induced formation of a boron-doped iron oxide shell on the surface of NZVI for enhancing nitrate removal.

The surface products have a significant influence on the reactivity of zero-valent iron-based materials. Although the enhancing effect of graphene on the reactivity of nanoscale zero-valent iron (NZVI)/graphene composites have been confirmed, the effect of graphene on the formation of surface products of NZVI is not well understood. In order to assess the effect of graphene on the structural of the outer iron oxide layers of NZVI, the NZVI was pre-oxidized by graphene oxide (ONZVI-GO). Compared with the NZVI oxidized by O2 (ONZVI-O2), ONZVI-GO was shown to be effective at NO3- removal with a high efficiency over a wide range of initial pH values. The results from characterization showed that GO could induce the formation of a tight iron oxide shell with dense spinel structures. The boron introduced during the preparation of NZVI was doped into iron oxides on the surface of ONZVI-GO. The B-O in adsorbed borate was transformed to B-B/B-Fe in the lattice structure of iron oxides, causing the formation of highly electron-deficient Lewis acid sites on the surface of ONZVI-GO, which could effectively gather NO3- and OH-, leading to the higher efficiency removal of NO3- than ONZVI-O2 over a wide range of initial pH values. This study provides new insight into the interaction between graphene and the surface species of NZVI.

Sustaining reactivity of Fe(0) for nitrate reduction via electron transfer between dissolved Fe(2+) and surface iron oxides.

The mechanism of the effects of Fe(2+)(aq) on the reduction of NO3(-) by Fe(0) was investigated. The effects of initial pH on the rate of NO3(-) reduction and the Fe(0) surface characteristics revealed Fe(2+)(aq) and the characteristics of minerals on the surface of Fe(0) played an important role in NO3(-) reduction. Both NO3(-) reduction and the decrease of Fe(2+)(aq) exhibited similar kinetics and were promoted by each other. This promotion was associated with the types of the surface iron oxides of Fe(0). Additionally, further reduction of NO3(-) produced more surface iron oxides, supplying more active sites for Fe(2+)(aq), resulting in more electron transfer between Fe(2+) and surface iron oxides and a higher reaction rate. Using the isotope specificity of (57)Fe Mossbauer spectroscopy, it was verified that the Fe(2+)(aq) was continuously converted into Fe(3+) oxides on the surface of Fe(0) and then converted into Fe3O4 via electron transfer between Fe(2+) and the pre-existing surface Fe(3+) oxides. Electrochemistry measurements confirmed that the spontaneous electron transfer between the Fe(2+) and structural Fe(3+) species accelerated the interfacial electron transfer between the Fe species and NO3(-). This study provides a new insight into the interaction between Fe species and contaminants and interface electron transfer.