We here report a spectroscopic identification of two new changing-look AGNs (CL-AGNs): SDSS J104705.16+544405.8 and SDSS J120447.91+170256.8 both with a "turn-off" type transition from type 1 to type 1.8/1.9. The identification is arrived by a follow-up spectroscopic observation of the five changing-look AGN (CL-AGN) candidates that are extracted from the sample recently released in Macleod et al. The candidates are extract by the authors from the Sloan Digit Sky Survey Data Release 7 spectroscopically confirmed quasars with large amplitude variability. By compiling a sample of 26 previously identified CL-AGNs, we confirm the claim in Macleod et al. that CL-AGNs tend to be biased against low Eddington ratio, and identify an overlap between the CL-AGNs at their dim state and the so-called intermediate-type AGNs. The overlap implies that there two populations of the intermediate-type AGNs with different origins. One is due to the torus orientation effect, and the another the intrinsic change of the accretion rate of the central supermassive blackholes.

Summary Long‐term application of fertilizers has a considerable effect on the accumulation of soil organic carbon (SOC), but the underlying processes remain unclear. We have examined the effects in the soil of two long‐term (> 20 years) field experiments of a double‐cropped maize (Zea mays L.)–wheat (Triticum aestivum L.) rotation on a Calcaric Fluvisol and paddy rice (Oryza sativa L) on a Hydragric Anthrosol. The chemical structures of the SOC were characterized with multiple cross‐polarization magic‐angle spinning 13C nuclear magnetic resonance spectroscopy. The treatments included organic fertilizer (OF) only, combined NPK (nitrogen, phosphorus and potassium) fertilizer with OF (NPKOF), mineral fertilizer pairings of NPK, NP and NK, and an unamended control. The continuous fertilizer treatments did not change the chemical composition of the Anthrosol SOC greatly except that the NPKOF treatment slightly enriched aromatic C and depleted O–alkyl C compared with the Control. All the treatments on the Anthrosol soil resulted in SOC accumulation, but to different extents. Principal component analysis of the Anthrosol and Fluvisol showed different relationships between the soil properties and functional groups. The Fluvisol SOC decreased in the order balanced fertilizer treatments (OF, NPKOF and NPK), NP, Control and NK treatments. The main structural changes of the Fluvisol SOC followed the same order with a decrease in the abundance of aromatic CO, aromatic C, anomeric C, O–alkyl C and OCH3/NCH, and an increase in COO/NCO and alkyl C, which led to an increase in alkyl–C/O–alkyl–C ratios and a decrease in aromaticity values. These results suggest that SOC accumulation with balanced fertilization on the Fluvisol can be attributed to less decomposition and more humification of the organic materials, whereas the smallest SOC content associated with P omission can be ascribed to more complete decomposition to gaseous end products. We consider that the chemical compositions of SOC may be altered by long‐term fertilizer treatments, depending on the soil type. Highlights How does soil organic carbon (SOC) change in response to long‐term fertilizer management? Improved understanding of SOC accumulation in Fluvisol and Anthrosol agricultural soils. Phosphorus omission in the Fluvisol retarded the accumulation and stimulated the decomposition of SOC. Fertilizer treatments affected chemical composition of SOC of the Fluvisol, but not the Anthrosol.

Rice paddy soils undergo several cycles of drying and wetting during a growing season. A laboratory study was conducted to determine the effect of soil moisture conditions on the distribution and kinetics of extractable and bound residues of 14C-metsulfuron-methyl in six Chinese paddy soils during 84 d of incubation at 15 degrees C with moisture contents varying from 20 to 50% of the field water-holding capacity. The amount of extractable residues consistently increased and bound residues decreased with increasing soil moisture content. At the end of the incubation experiments, extractable residues and bound residues accounted for 34.5 to 84.4% and 11.6 to 53.3% of applied radioactivity in soils, respectively. Soil pH and soil microbial biomass carbon were the most predominant factors affecting the formation and relative distribution of herbicide residues between extractable and bound residue forms. In high-pH soils, bound residues decreased and extractable residues increased, suggesting an increased leaching risk for metsulfuron-methyl in alkaline soils. High precipitation rates, along with the common practice of liming in southeastern China, may lead to enhanced herbicide leaching as well as phytotoxicity to rotation plants and should be considered in overall pest management practices.