Direct hydroxylation of benzene to phenol using molecular oxygen is a green route with high atom economy but still a great challenge when compared with the existing method of production. The activation of oxygen is necessary and reductive agents were used to activate dioxygen in a so-called “reductive activation” process. Here, nano vanadium oxides that consist mainly of low valence vanadium to activate dioxygen were prepared under different conditions via a hydrothermal method. Under the optimized conditions, an excellent phenol selectivity of 96.3% with benzene conversion of 4.2% was achieved over the VOC₂O₄–N-5 without reductive agents. Characterizations revealed that VOC₂O₄–N-5 was composed of a mesoporous nanosphere structure with medium strong acid sites and low valence vanadium species. A mechanism was proposed as follows: dioxygen was activated by low valence vanadium in VOC₂O₄–N-5 to produce the active oxygen species which oxidized acetic acid to peracetic acid. Then the active oxygen species was subsequently transferred from peracetic acid to benzene and inserted into the C–H bond to give phenol.

Expected changes in precipitation over large regions of the world under global climate change will have profound effects on terrestrial ecosystems in arid and semiarid regions. To explore how changes in the amount of precipitation in the growing season would affect soil nitrogen (N) availability in a semiarid ecosystem, we established rainout shelters and irrigation systems by simulating 30% reduced (DRY) and 30% increased precipitation (WET) relative to natural precipitation (Control) to measure some key soil process properties for two growing seasons in a nutrient-poor Mongolian pine (P. sylvestris var. mongolica) plantation. Both WET and DRY treatments significantly affected monthly soil inorganic nitrogen concentrations, which showed a higher inorganic N under DRY than Control in each month and lower in WET than Control. Monthly soil microbial biomass N content was reduced by DRY and raised by WET treatments. The results indicated the asynchrony of the availability of soil moisture and soil nutrients in Mongolian pine plantations at the Horqin Sandy Lands in Northeast China. Water limited plant growth in Mongolian pine plantations when precipitation decreased, and nitrogen limitation became increasingly important when precipitation increased. Accumulation of N in microbial biomass is an important mechanism for N cycling in this ecosystem. To effectively manage Mongolian pine plantations, it is advised that evapotranspiration is minimized when precipitation decreases and that there is an increase in soil N availability by protecting litterfall when precipitation increases.

To understand the relative importance of plant community composition and plant-induced soil properties on N transformations, the soil N mineralization, ammonification and nitrification characteristics of natural secondary forests (Quercus mongolica-Juglans mandshurica forest: QJF, and Quercus mongolica-Populus davidiana forest: QPF) and the adjacent larch plantations (Larix kaempferi forest: LF1 and LF2) were studied during the growing season. All of the forest types showed seasonal dynamics of N mineralization rates. The total cumulative N mineralization was significantly higher in QPF (73.51 kg hm⁻²) than in LF1 (65.64 kg hm⁻²) and LF2 (67.51 kg hm⁻²) (p < 0.05). The total cumulative nitrification from May to November was significantly higher in QJF (65.16 kg hm⁻²) and QPF (64.87 kg hm⁻²) than in LF1 (52.62 kg hm⁻²) and FL2 (54.17 kg hm⁻²) (p < 0.05). Based on the variation partitioning, independent soil properties were the primary determinants of the N transformations (13.5%). Independent climate conditions explained 5.6% of the variations, while plant variations explained 3.2% of the variations in N transformations. We concluded that different forest types with various plant community compositions have different influences on the litterfall quantity and quality and the nutrient availability, and these differences interact with seasonal climate conditions that in turn drive the differences in N mineralization.

Estimating regional nutrient criteria for streams and rivers is a key step toward protecting river water quality and restoring the health of aquatic ecosystems. Using a multivariable statistical analysis technique, nutrients were identified as the main factor influencing the degradation of the benthic macroinvertebrate community. Three chemical methods (the reference stream distribution approach, all-streams distribution approach and Y-intercept approach) and one biological method (the stress-response approach) were applied to evaluate the nutrient thresholds in the Qing River basin. The reference stream distribution approach and all-streams distribution approach were based on calculating a predetermined percentile of reference streams and all-streams water quality data set, respectively. The Y-intercept approach was based on determining the influence of human activity on water quality by linear regression models. The biological method was based on the response of the benthic macroinvertebrate community structure to changes in water quality. The chemical thresholds were 0.750–1.288 mg/L for total nitrogen (TN) and 0.035–0.046 mg/L for total phosphorus (TP); the biological thresholds were 1.050–1.655 for TN and 0.052–0.101 for TP. The results from the chemical approaches were verified using the biological method, resulting in preliminarily recommended thresholds of 1.000 mg/L TN and 0.040 mg/L TP in the Qing River system.