Effects of oil pollution on soil microbial diversity in the Loess hilly areas, China

Abstract Purpose Data support and theoretical basis for bioremediation and treatment of petroleum-contaminated soils in the Loess hills of Yan’an, northern Shaanxi. Methods The evolutionary characteristics of soil microbial diversity and community structure under different levels of oil pollution were studied by field sampling, indoor simulation experiments, and analyzed through assays, using the mine soils from Yan’an, Shaanxi Province, as the research object. Results Compared with clean soil, the microbial species in contaminated soil were significantly reduced, the dominant flora changed, and the flora capable of degrading petroleum pollutants increased significantly. The soil microbial diversity and community structure differed, although not significantly, between different pollution levels, but significantly from clean soil. In the uncontaminated soil (CK), the dominant soil microbial genera were mainly Pantoea, Sphingomonas, Thiothrix, and Nocardioides. The abundance of Pseudomonas, Pedobacter, Massilia, Nocardioides, and Acinetobacter in the soil increased after oil contamination, while Thiothrix, Sphingomonas, and Gemmatimonas decreased significantly. Conclusions After the soil was contaminated with petroleum, the microbial species in the soil decreased significantly, the dominant genera in the soil changed, and the relative abundance of bacteria groups capable of degrading petroleum pollutants increased. The genera that can degrade petroleum pollutants in the petroleum-contaminated soil in the study area mainly include Pseudomonas, Acinetobacter, Pedobacter, Acinetobacter, and Nocardioides, which provide a scientific basis for exploring It provides a scientific basis for exploring remediation methods suitable for petroleum-contaminated soil in this region

Effects of large-scale land consolidation projects on ecological environment quality: A case study of a land creation project in Yan'an, China

Large land consolidation projects modify the structures and functions of regional ecosystems through the reshaping of the territorial spatial pattern, thereby affecting the ecological environmental quality (EEQ). To investigate the effects of large-scale land consolidation projects on EEQ, this study takes the major land consolidation project of “bulldoze mountains to create land” (BMCL) in Yan'an City as a research object and evaluates the change of EEQ based on Remote Sensing Ecological Index (RSEI). The consolidated area and the control area were set up to comparatively analyze the EEQ change processes and spatial distribution characteristics of these two areas in the full life cycle of BMCL. According to the results, the mean RSEI of the consolidated area was 0.128 lower than that of the control area, and the EEQ of the consolidated area was always lower than that of the control area. BMCL had a strong negative impact on the EEQ grade of the consolidated area, especially in the early stage. However, the positive effect of BMCL on EEQ gradually emerged in the late stage of the large land consolidation project. The overall EEQ grade of the consolidated area has also improved. The results of the stepwise regression analysis indicated that the wetness component and the normalized differential vegetation index played key roles in improving the EEQ of the BMCL. Overall, the local BMCL strongly affected the EEQ of the consolidated area but would not cause the EEQ of the whole region to experience any dramatic, abrupt change in the short term. This study provided references for the evaluation and analysis of the ecological effects of land consolidation at the regional scale, offering a feasible way to evaluate the spatio-temporal change of EEQ in BMCL

Effects of climatic conditions and vegetation changes on actual evapotranspiration in Mu Us sandy land

Based on the MOD16A3GF data, spatial regression analysis was conducted to explore the trends of the annual change of AET and the characteristics of its spatial distribution in Mu Us Sandy Land between 2001 and 2020. Combined meteorological data and NDVI data to analyze its effects on AET by trend analysis and correlation coefficient. The results showed that (1) The AET exhibited significant regional differences in Mu Us Sandy Land, with an overall low northwest and high southeast distribution pattern; (2) The AET showed a rapid upward trend from 2001 to 2020, with an average rate of change of 5.68 mm·a-1; (3) The correlation coefficient between AET and precipitation was 0.74, and there was no obvious correlation with temperature; (4) AET was consistent with the NDVI spatial distribution and interannual variation curves. Under the combined influence of precipitation and NDVI, AET increased significantly in Mu Us Sandy Land from 2001 to 2020. Precipitation was the main factor affecting climatic conditions of AET, and NDVI was the dominant factor affecting AET in the same period. This provides a theoretical basis and scientific basis for the conservation and protection of ecological water source in Mu Us Sandy Land. HIGHLIGHTS Mu Us Sandy Land is a key area in China for implementing ecological engineering.; The spatial and temporal patterns of AET, hydrothermal conditions, and vegetation changes were studied.; The average annual water surface evaporation monitored at eight weather stations was counted.; The annual average NDVI and ET were divided into six levels.; The climatic conditions are not the main factor of AET variation.

Long-Term Moderate Oxidative Stress Decreased Ovarian Reproductive Function by Reducing Follicle Quality and Progesterone Production

<div><p>Ovarian aging is a long-term and complex process associated with a decrease in follicular quantity and quality. The damaging effects of reactive oxygen species (ROS) in ovarian aging and ovarian aging-associated disorders have received relatively little attention. Thus, we assessed if the oxidative stress induced by long-term (defined by the Environmental Protection Agency as at least 30 days in duration) moderate ozone inhalation reduced ovarian reserves, decreased ovarian function and induced ovarian aging-associated disorders. The expression of oxidative stress markers and antioxidant enzymes was used to determine the degree of oxidative stress. Ultrastructural changes in ovarian cells were examined via electron microscopy. The ovarian reserve was assessed by measuring multiple parameters, such as the size of the primordial follicle pool and anti-Müllerian hormone (AMH) expression. The estrous cycle, hormone levels and fertility status were investigated to assess ovarian function. To investigate ovarian aging-associated disorders, we utilized bone density and cardiovascular ultrasonography in mice. The levels of oxidized metabolites, such as 8-hydroxy-2´-deoxyguanosine (8-OHdG), 4-hydroxynonenal (4-HNE) and nitrotyrosine (NTY), significantly increased in ovarian cells in response to increased oxidative stress. The ultrastructural analysis indicated that lipid droplet formation and the proportion of mitochondria with damaged membranes in granulosa cells were markedly increased in ozone-exposed mice when compared with the control group. Ozone exposure did not change the size of the primordial follicle pool or anti-Müllerian hormone (AMH) expression. The estrogen concentration remained normal; however, progesterone and testosterone levels decreased. The mice exposed to ozone inhalation exhibited a substantial decrease in fertility and fecundity. No differences were revealed by the bone density or cardiovascular ultrasounds. These findings suggest that the decreased female reproductive function caused by long-term moderate oxidative damage may be due to a decrease in follicle quality and progesterone production.</p></div

Assessment of ovarian, endocrine and reproductive function.

<p>(A) The ovarian weights of both groups. (B) The estrous cycles of the OI mice were normal when compared with the NC mice. Using EIA kits, the concentrations of 17β-estradiol (C) progesterone (D) and testosterone (E) were determined in duplicate. The data are shown as the mean ± SEM obtained from 6 animals. The mean litter size (F) and the mean number of litters (H) during a 6-month period were calculated as previously described. The OI mice showed decreased litter sizes and less overall litters when compared with the NC group. The data are shown as the mean ± SEM. N = 6 per group. <i>*</i> P<0.05 when compared with the NC.</p

Picture and schematic representation of the ozone chamber and ozone generator.

<p>Note: 1. ozone generator; 2. interval timer; 3. exhaust fan; and 4. ozone chamber.</p

Effects of ozone inhalation on oxidative damage and antioxidant enzymes.

<p>(A) The immunostaining results (dark brown) for the oxidative damage in the interstitial cells and follicles in the ovaries of NC and OI mice, including oxidative DNA damage (8-OHdG), lipid peroxidation (4-HNE) and protein oxidation (NTY). (B-C) The percentage of positively-stained granulosa cells in healthy and atretic follicles. (D-E) The percentage of positively-stained theca cells in healthy and atretic follicles. (F) The percentage of positively-stained interstitial cells in the ovaries. (G) The protein expression of SOD2 was significantly increased following ozone exposure. Values represent the mean ± SEM, and the data were obtained from 3 independent experiments (*P<0.05 and **P<0.01 when compared with the NC group).</p

Body weight and exhausted swimming time for each group.

<p>(A) Representative images of mice in the NC and OI groups. (B) There was no significant difference in body weights between the two groups. (C) The exhausted swimming time of the OI mice was substantially decreased when compared with the control group (*P<0.05 when compared with the control group).</p