Drought and vegetation dynamics in the northern Xinjiang Uygur Autonomous Region of China (NXC), the centre of Asia with arid climate, were assessed using the standardized precipitation evapotranspiration index (SPEI) and the normalized difference vegetation index (NDVI). Analyses were performed through the use of Sen’s method and Spearman’s correlation to investigate variations in the NDVI and the impacts of drought on vegetation from 1998 to 2015. The severity of droughts in the NXC was assessed by the SPEI, which was revealed to increase over the last 60 years at a rate of 0.017 per decade. This indicates that an alleviating tendency of drought intensity occurred in the NXC. Specifically, the spatial pattern of drought intensity increased gradually from the north-western to south-eastern regions. The average yearly NDVI was 0.28 and increased slightly by 0.001 yr⁻¹ (r = 0.94, p = 3.64) between 1998 and 2015. Additionally, the NDVI showed an obviously spatial heterogeneity, with greater values in the west and small values in the east. Significantly, positive correlations between SPEI and NDVI were observed, while drought exerted a five-year lag effect on vegetation.

Biochar and nitrogen fertilizers are known to increase soil carbon storage and reduce soil nitrogen loss as amendments, suggesting a promising strategy for highly effectively increasing soil productivity. However, few studies have explored the mechanisms of their effects on crop yield in terms of active carbon fraction and enzyme activity, which ultimately limits the potential for the application of biochar in combination with nitrogen fertilizers. To evaluate the effect of biochar and nitrogen fertilizer on the improvement of black soils in northeast China, a field experiment was conducted in the black soil to compare and analyze the application methods on total organic carbon (TOC), total nitrogen (TN), enzyme activities, and maize yields. Biochar rates: CK, C1, C2, and C3 (0, 9.8, 19.6, and 29.4 Mg·ha⁻¹); N fertilizer rates: N1/2 and N (30 and 60 kg·ha⁻¹). Results indicated that biochar and N fertilizer amendments significantly ameliorated soil fertility, such as TOC and TN, compared to the unamended soil. The TOC levels in the C3 treatment increased by 35.18% and the TN levels by 23.95%. The improvement in TN is more significant when biochar is blended with N fertilizer. Biochar blended with N fertilizer increased maize cellulase, urease, and invertase activities by an average of 53.12%, 58.13%, and 16.54%, respectively. Redundancy analysis showed that TOC, TN, and MBN contributed 42%, 16.2%, and 22.2%, respectively, to the maize yield indicator. Principal component analysis showed that reduced N fertilizer was more effective in improving yields, with a maximum yield increase of 50.74%. Biochar blended with N fertilizer is an effective strategy to improve the fertility and productivity of black soils in northeast China, while nitrogen fertilizer reduction is feasible and necessary for maintaining grain yield.

Alpine mountain peatlands are valuable archives of climatic and anthropogenic impact. However, the impacts of human activities on the Altay peatlands are poorly documented. Therefore, studying heavy metal (HM) concentrations, evaluating HM pollution levels, and identifying the sources in the Altay Mountain peatlands are crucial for revealing the intensity of human activities. The present study was performed on two peatland profiles: Jiadengyu (JDY) and Heihu (HH). The contents of HM and ²¹⁰Pb and ¹³⁷Cs dating technologies were used to construct a profile of anthropogenic pollutant distributions in the peatlands. Furthermore, the enrichment factor (EF) and geo-accumulation index (Igeo) of selected HMs were used to evaluate the risk assessment of HMs. The association of metals and assignment of their probable sources were examined using principal component analysis (PCA) and a positive matrix factorization model (PMF). The results showed that the concentrations of elements Cu, Zn, Cr, Pb, Ni, and As were at high levels in the two peatlands of the Altay Mountains, while the elements Hg and Cd were in low concentrations. Moreover, the concentrations of Cu, Cd, Hg, and Sb were higher than the background values of local element and posed a high environmental risk to the ecosystem. Combined with the results of the chronology, the peatland records indicated considerable growth in HMs concentrations from 1970 to 1990 related to recent anthropogenic activities. Additionally, the main sources of HMs are mining activities, domestic waste, and traffic sources in the two peatlands. Due to the environmental protection policies implemented since 2010, the natural processes have been the primary origin of HMs in peatlands, while emissions of industrial, agricultural, and domestic waste were still fundamental sources. The results of this study describe the sedimentary features of HMs in alpine mountains, and the data provide an essential theoretical basis for the evolutionary process through the characteristics of HM deposition.

Managing carbon input from crop straw in cropland ecosystems could increase soil organic carbon (SOC) sequestration to achieve C neutrality and mitigate climate change. The complexity of the chemical structures of crop residue largely affects SOC sequestration. Fungi communities play an important role in the degradation of crop residues. However, the relationship between the fungal community composition and the chemical structures of crop residues remains unclear and requires further investigation. Therefore, a 120-day incubation experiment was conducted in Mollisols in Northeast China to investigate the decomposition processes and dynamics of maize straw stem (ST), leaf (LE) and sheath (SH) residues using ¹³C-NMR spectroscopy. Additionally, the microbiomes associated with these residues were analyzed through high-throughput sequencing to explore their relationship. Our results showed that the alkyl C contents in all treatments exhibited increases ranging from 15.1% to 49.1%, while the O-alkyl C contents decreased, ranging from 0.02% to 11.2%, with the incubation time. The A/OA ratios of ST, LE and SH treatments were increased by 23.7%, 43.4% and 49.3% with incubation time, respectively. During the early stages of straw decomposition, Ascomycota dominated, and in the later stage, Basidiomycota were predominant. The class of Sordariomycetes played a key role in the chemistry transformation of straw tissues during decomposition. The keystone taxa abundances, Fusarium_kyushuense, and Striatibotrys_eucylindrospora, showed strong negative correlations with di-O-alkyl C and carbonyl-C content and positive correlations with the β-glucosidase and peroxidase enzyme activity, respectively. In conclusion, our study demonstrated that the keystone taxa play a significant role in regulating the chemical structures of straw tissues, providing a better understanding of the influence of residue quality on SOC sequestration.

In the collection of dust, vacuum cleaners are used to clean everything inside the car, including floor/carpet, seat, console, etc. To investigate the characteristics, possible sources and carcinogenic risks of polycyclic aromatic hydrocarbons (PAHs) contamination in car dust, fourteen car dust samples were collected from commercial car washes in Changchun, Northeast China. The 16 priority PAHs were all detected in 100%, and PAHs were predominantly tetracyclic. The mean ∑16PAHs content was 9297.79 ± 5855.89 ng g⁻¹, ranging from 2940.03 to 23,174.51 ng g⁻¹. Black carbon, total carbon and PAHs were weakly correlated. The results of positive matrix factorization indicated that coal combustion contributed 30.03% of PAHs and biomass combustion contributed 24.70%. Vehicle exhaust from traffic emissions, mainly incomplete combustion of gasoline and diesel, contributed 45.27% of PAHs. The mean incremental lifetime cancer risk (ILCR) values for children and adults were 4.94 × 10⁻³ and 4.37 × 10⁻³, respectively, both above the threshold value of 10⁻⁴. This indicates that PAHs from car dust put both adults and children at high carcinogenic risk, and that children are exposed to a higher carcinogenic risk than adults. This study provides a basis for proposing targeted measures to control PAHs’ contamination from car dust.

In order to solve the problem of low and poor straw degradation in typical black soil areas of Northeast China, the present study was carried out to screen the potential of in situ strains with cellulose degradation ability from black soils of Northeast China to play a role in the resourceful utilization of straw and the development of sustainable agriculture. The straw degradation potential of the strains was evaluated by combining sodium carboxymethyl cellulose plate screening and cellulase viability assay; the species identification of the strains was carried out by morphology, physiology, biochemistry, and molecular biology; and the basic medium formulation of the strains was optimized by Box–Behnken response surface methodology. Ten cellulose-degrading strains were identified: ZL-5, ZL-69, ZL-88, ZL-95, ZL-111, ZL-137, ZL-139, ZL-140, ZL-187, and ZL-216, of which ZL-139 had the highest cellulase production capacity, with a cellulase secretion of 7.8781 U/mL in the enzyme-producing medium. ZL-139 was identified as Bacillus cereus; the optimized best formulation was glucose—4.284 g/L, yeast extract—1.454 g/L, MgSO₄—0.417 g/L, KH₂PO₄—0.5 g/L, KH₂PO₄—0.5 g/L, K₂HPO₄—1.5 g/L, and NaCl—1.0 g/L. In conclusion, strain ZL-139 has good potential for crop straw degradation and can be a candidate strain for a straw-rotting agent in northeast China, with promising prospects for development and utilization.