Dyerlangley5974

The trend of deposition rate was first increasing and then decreasing. After the year 1980, the deposition rate was substantially decreasing, which was consistent with the prohibition of PCBs production in the United States in 1979. Meanwhile, the analysis of sediment samples in the lake near bog showed that concentration and maximum deposition rate of the lake sediment were comparable to those of the nearby bog. The concentrations of Di- to Hepta-PCB congeners were evenly distributed along the sediment profile. Therefore, lake sediments could not be used to analyze the historical sedimentary model of low order PCBs. This study reconstructed temporal and spatial variation of PCBs in atmospheric environment in different historical periods, which could provide basic data for the evaluation of regional environmental quality.Bacillus laterosporus Bl13 has good antagonistic effect on the pathogen of tomato early blight (TEB) disease. A pot experiment was conducted to investigate the effect and mechanism of B. laterosporus Bl13 against TEB disease by measuring biological traits such as plant height, stem diameter, disease index of TEB, activity of plant defense enzyme in leaves, and microbial diversity and community composition in root area. The results showed that B. laterosporus Bl13 could significantly reduce the disease index of TEB disease incidence, increase the activity of defensive enzymes including polyphenol oxidase (PPO) and peroxidase (POD) in leaves, and reduce the effects of the disease on the aboveground and root growth of tomato. Meanwhile, B. laterosporus Bl13 improved soil microbial community structure in the root zone, by significantly increasing the relative abundance of plant growth-promoting bacteria (Bacillus and Pseudomonas) and decreasing that of Olpidium and Haematonectria. The results showed that B. laterosporus Bl13 could enhance plant resistance against TEB disease through improving the activity of defensive enzymes in tomato leaves and increasing the number of beneficial microbes in the root zone.Evapotranspiration is the key element of hydrological energy cycle and climate system. It is of great significance to estimate the spatiotemporal variation of evapotranspiration and its response to climate and land use changes for understanding the effects of water cycle and ecological processes in urban basins. Based on the three-temperature model and MODIS Image, we estimated and analyzed the spatiotemporal variation of evapotranspiration in Nanning City from 2001 to 2018, and examined the influence and driving mode of main climate factors and land use types on evapotranspiration. The results showed that the annual average evapotranspiration of Nanning City ranged from 495.7 to 781.1 mm during 2001-2018, with the inter annual relative variability ranging from -22.5% to 23.1%, showing an overall upward trend. The regional evapotranspiration showed a distribution pattern of high north-south and low middle, with the urban evapotranspiration being significantly lower than suburban area. The evapotranspiration had a significant multiple correlation with climate factors. The influence of temperature on the evapotranspiration was stronger than precipita-tion. Evapotranspiration was temperature driven in suburbs, but was driven by multiple factors in urban area. The average evapotranspiration of different land use types in Nanning was forests (823.4 mm) > grasslands (675.6 mm) > croplands (582.9 mm) > urban area (346.6 mm). selleck The change of land use type was the main underlying surface factor leading to the significant change of regional evapotranspiration.Based on grid sample method (20 m×20 m), spatial heterogeneity and distribution of soil water physical properties from 0 to 5 cm of the coal gangue pile in arid desert area were explored by using classical statistics and geostatistics methods. The results showed that the variation of soil bulk density, capillary porosity, capillary maximum moisture capacity, total porosity and saturated moisture contents were weak, while water content showed a moderate variation. The best fitting model of soil bulk density was Gaussian model, and exponential model was the best fitting model for other indices. The C0/(C0+C) values of soil bulk density and water content were low and had strong spatial autocorrelation. The capillary porosity, capillary maximum moisture capacity, total porosity and soil saturated moisture showed moderate spatial autocorrelation. Soil bulk density was negatively correlated with capillary porosity, capillary maximum moisture capacity, total porosity and water content, whereas there was no significaorm and suitable soil water physical conditions for vegetation restoration.Based on the runoff and sediment yield data from 59 erosive rainfall plots with different slope lengths (5, 10, 15, 20, 25 m) in Shiqiao small watershed of Guizhou Province from 2012 to 2014, we analyzed the relationship between runoff and sediment yield and slope length under diffe-rent rainfall conditions. The results showed that, with the increases of slope length, the runoff yield of slope showed a 'V-shape' pattern, the sediment yield of slope increased first and then decreased. According to rainfall amount, rainfall duration, and average rainfall intensity, the 59 erosive rainfall in the study area could be divided into three types, including type A with short duration, heavy rain intensity and small rainfall, type B with medium duration, light rain intensity and medium rainfall, and type C with long duration, medium rain intensity and large rainfall. The relationships between runoff and sediment yield and slope length were different under different rainfall patterns. There was about 20 m critical slope amount (P), the pro-duct of rainfall duration and maximum 30 min rainfall intensity (TI30), product of rainfall duration and average rainfall intensity (TI), product of rainfall amount and rainfall duration (PT) were significantly correlated with the runoff and sediment yield. Among those factors, P and TI had the strongest correlation with runoff. Further, the relationship between them and runoff under different slope lengths could be expressed by linear equation and S-curve. There was a good cubic function relationship between the sediment yield and its corresponding rainfall factors under different slope lengths.The rapid urbanization has greatly changed the spatial pattern and function of regional habitats, profoundly affected the material flow and energy flow between habitats, and also posed a serious threat to habitats and biodiversity. Here, we used InVEST model, landscape index and multiple linear regression to systematically analyze the spatial and temporal variation and influencing factors for the impacts of urbanization on habitat quality in the Loess Plateau and the densely populated areas from 1990 to 2018. The results showed that the urban expansion of Loess Plateau significantly affected habitat quality. Between 1990 and 2018, the area of construction land increased by 49.6%, resulting in a 5.2% reduction in the total area of habitat patch. After 2010, the urban patch area increased, but the patch density and fragmentation decreased, resulting in a spatial pattern of "high outside and low inside" for urban habitat quality. The rate of urban expansion in densely populated areas was significantly negatively correlated with the habitat quality. The average value of habitat quality in the region dropped by 2.7%, whereas the level of habitat degradation increased by 33.4%. The level of habitat quality was unstable, and patches with high-level habitats were easily converted to lower level. The conversion rates of Lanzhou, Xi'an-Xianyang and Taiyuan were 12.9%, 2.9% and 1.7%, respectively. There were eight influencing factors that could effectively explain the spatial variation of habitat quality (R2=68.7%). Among those factors, population density and distance to roads were the main factors for the fragmentation of habitats, while slope, GDP and precipitation had positive effects on the optimization of habitat spatial patterns.It is objective needs during utilization and management of regional cultivated land resource to use remote sensing to accurately and efficiently retrieve the status of cultivated land fertility at county level and realize the gradation of cultivated land rapidly. In this study, with Dongping County as a case, using Landsat TM satellite imagery and cultivated land fertility evaluation data, the moisture vegetation fertility index (MVFI) was constructed based on surface water capacity index (SWCI) and normalized difference vegetation index (NDVI), and then the optimal inversion model was optimized to obtain the best inversion model, which was further applied and verified at the county scale. The results showed that the correlation coefficient between MVFI and integrated fertility index (IFI) was -0.753, which could comprehensively reflect the growth of winter wheat, soil moisture and land fertility, and had clear biophysical significance. The best inversion model was the quadratic model, with high inversion accuracy. This model was suitable for the inversion of cultivated land fertility in the county. The spatial distribution and uniformity of the inversion results were similar to the results of soil fertility evaluation. The area differences between the high, medium and low grades were all less than 2.9%. This study provided a remote sensing inversion method of cultivated land fertility based on the feature space theory, which could effectively improve the evaluation efficiency and prediction accuracy of cultivated land fertility at the county scale.Multiple agrometeorological disaster (MAD) occurs simultaneously in maize production. In order to ascertain the occurrence regularity and characteristics of MAD of maize in Liaoning Pro-vince, we defined and classified MAD, identified MAD of 50 meteorological stations in the maize growing season of Liaoning Province from 1961 to 2017, and examined the effects of MAD on maize yield in typical years. The results showed that the occurrence range of MAD was higher in most years from 1961 to 2017 than that of single agrometeorological disaster (SAD), and that the occurrence frequency of MAD was higher in most areas than that of SAD. The major MAD in Liaoning Province was drought in multiple periods (M1-D), followed by the combination of drought and delayed cold damage (M2-DC). The occurrence range of M1-D showed an upward trend from 1961 to 2017, whereas other MAD types showed a downward trend. After analyzing the occurrence of MAD in the typical years of maize yield reduction, we found that the occurrence frequency of M1-D and M2-DC was higher.Strawberry variety 'Benihoppe' was used as the experimental material. The temperature treatments were set at 32 ℃/22 ℃, 35 ℃/25 ℃, 38 ℃/28 ℃ and 41 ℃/31 ℃ (daily maximum temperature/daily minimum temperature), and the stress days lasted for 2, 5, 8 and 11 d, with 28 ℃/18 ℃ as the control. We measured the photosynthetic characteristics, chlorophyll fluorescence characteristics, reactive oxygen species, protective enzyme activity and membrane lipid peroxidation of strawberry under different high temperature treatments. The key indices were extracted by principal component analysis. The high temperature stress index (Z) was defined to divide the high temperature stress grade. The results showed that 1) with the aggravation of high temperature stress and the extension of stress time, chlorophyll a (Chl a), chlorophyll b (Chl b), carotenoid (Car), light saturation point (LSP), maximum net photosynthetic rate (Pmax), apparent quantum efficiency (AQE) and maximum photochemical efficiency (Fv/Fm) decreased, while light compensation point (LCP) and dark respiration rate (Rd) increased.