Geostatistical analysis and risk assessment on soil total nitrogen and total soil phosphorus in the Dongting Lake plain area, China

Nonpoint-source pollution and water body eutrophication have become increasing concerns for scientists and policymakers. Nitrogen and phosphorus affect environmental pollution, especially lake eutrophication. To assess the environmental risk of soil total nitrogen (TN) and total phosphorus (TP) pollution, a typical ecological unit of Dongting Lake plain was selected as the experimental site. To verify the stationary of the data, a moving windows technique was adopted. Our results showed that Box-Cox transformation achieved normality in the data set and dampened the effect of outliers. The best theoretical model for semivariogram of TN and TP was a spherical model. The ordinary kriging estimates of TN and TP concentrations were mapped. The integrative comparisons of semivariogram parameters with different trends to the kriging prediction errors of TN and TP indicated that the two-order trend is preferable. Kriging SDs provided valuable information that will increase the accuracy of TN and TP mapping. The probability kriging method is useful to assess the risk of N and P pollution by providing the conditional probability of N and P concentrations exceeding the threshold concentrations of 3.2 and 1.05 g/kg, respectively. The probability distribution of TN and TP at different levels will be helpful to conduct risk assessment, optimize fertilization, and control the pollution of N and P.     

Methane oxidation in freely and poorly drained grassland soils and effects of cattle urine application

A sink for atmospheric methane (CH4) is microbial oxidation in soils. We report CH4 oxidation rates in freely and poorly drained soils on an intensively managed dairy farm. Following cattle urine application to half the plots (650 kg of nitrogen [N] ha(-1)) 31 chamber measurements were made over 100 d during autumn and winter. In the control plots, the freely and poorly drained soils' integrated CH4 oxidation rates averaged 1.8+/-0.2 and 0.6+/-0.1 kg CH4 ha(-1) yr(-1), respectively. In the poorly drained soil, the highest CH4 oxidation rates occurred when water-filled pore space (WFPS)<56% and CH4 oxidation rate declined by ninefold to near zero as WFPS increased from 56 to 68%. Urine application induced the freely and poorly drained soils' CH4 oxidation rates to decline for up to 2 mo by 0.7+/-0.2 and 0.4+/-0.1 kg CH4 ha(-1) yr(-1), respectively. The two soils' responses were thus not significantly different. After urine application, soil pore space CH4 concentration profiles suggested a simultaneous inhibition of bacteria that were CH4 oxidizers and stimulation of CH4 producers.     

Biofilm-overproducing Bacillus subtilis B12ΔYwcc decreases Cd uptake in Chinese cabbage through increasing Cd-immobilizing related gene abundance and root surface colonization

Biofilm-producing bacteria can decrease Cd uptake in vegetables, but mechanisms underlying this effect are poorly characterized. In this study, two mutant strains B12ΔYwcc and B12ΔSlrR were constructed from a biofilm-producing Bacillus subtilis strain B12. Then, the impacts of strain B12 and its high biofilm-producing mutant strain B12ΔYwcc and low biofilm-producing mutant strain B12ΔSlrR on Cd availability and uptake in Chinese cabbage and the related mechanisms were investigated in the Cd-polluted soil. Strain B12 and its mutants B12ΔYwcc and B12ΔSlrR increased the dry biomasses of edible tissues by 54%–130% compared with the controls. Strain B12 and its mutant B12ΔYwcc reduced the soil available Cd content by 36%–50% and root and edible tissue Cd contents by 23%–50% compared with the controls. Furthermore, the mutant strain B12ΔYwcc reduced the edible tissue Cd content by 40% and increased the polysaccharide content by 23%, invertase activity by 139%, and gene copies of the cumA by 4.5-fold, epsA by 7.1-fold, and cadA by 4.3-fold, which were involved in Cd adsorption in the rhizosphere soils, respectively, compared with strain B12. The polysaccharide content and cumA, epsA, and cadA gene copy numbers showed significantly reverse correlations with the available Cd content. Notably, the mutant strain B12ΔYwcc showed better ability to colonize the vegetable root surface than strain B12. These findings demonstrated that the biofilm-overproducing mutant strain B12ΔYwcc increased the polysaccharide production and Cd-immobilizing related cumA, epsA, and cadA gene copies, resulting in lower Cd availability and accumulation in Chinese cabbage in the Cd-polluted soil.     

Chemical characterization and source identification of PM2.5 in Luoyang after the clean air actions

Luoyang is a typical heavy industrial city in China, with a coal-dominated energy structure and serious air pollution. Following the implementation of the clean air actions, the physicochemical characteristics and sources of PM_2.5 have changed. A comprehensive study of PM_2.5 was conducted from October 16, 2019 to January 23, 2020 to evaluate the effectiveness of previous control measures and further to provide theory basis for more effective policies in the future. Results showed that the aerosol pollution in Luoyang in autumn and winter is still serious with the average concentration of 91.1 μg/m³, although a large reduction (46.9%) since 2014. With the contribution of nitrate increased from 12.5% to 25.1% and sulfate decreased from 16.7% to 11.2%, aerosol pollution has changed from sulfate-dominate to nitrate-dominate. High NO₃⁻/SO₄²⁻ ratio and the increasing of NO₃⁻/SO₄²⁻ ratio with the aggravation of pollution indicating vehicle exhaust playing an increasingly important role in PM_2.5 pollution in Luoyang, especially in the haze processes. Secondary inorganic ions contributed significantly to the enhancement of PM_2.5 during the pollution period. The high value of Cl⁻/Na⁺ and EC concentration indicate coal combustion in Luoyang is still serious. The top three contributor sources were secondary inorganic aerosols (33.3%), coal combustion (13.6%), and industrial emissions (13.4%). Close-range transport from the western and northeastern directions were more important factors in air pollution in Luoyang during the sampling period. It is necessary to strengthen the control of coal combustion and reduce vehicle emissions in future policies.     

不同施肥措施下长江经济带地区农田土壤有机碳含量的变化分析

收集整理1992年1月至2022年5月长江经济带地区长期定位施肥试验文献,提取并整合了其中农田土壤有机碳的资料.采用归一化处理和变化速率的分析方法,研究长期不同施肥措施下长江经济带地区农田土壤有机碳含量的总体变化,并比较3种耕作模式及不同土壤类型下土壤有机碳含量的变化差异,判断分析试验持续年限长短对土壤有机碳动态的影响.结果表明,在长期不同施肥措施下,我国长江经济带地区农田土壤有机碳含量整体呈上升趋势,无机氮肥磷肥配施(NP)、无机氮磷钾肥配施(NPK)、单独施用有机肥(O)和有机无机肥配施(NPKO)处理均能增加农田土壤的有机碳含量,其中以NPKO处理为最大,而单独施用无机氮肥(N)则会降低土壤有机碳含量.旱田、水田和水旱轮作农田土壤有机碳含量变化速率分别为0.22、 0.24和0.16g·(kg·a)^-1,3种耕作模式在土壤固碳效果方面并无显著性差异.O和NPKO处理下所带来的有机碳相对快速增加效应在旱田土壤中的持续年限最高不超过28 a,而在水田及水旱轮作土壤中依然可以持续到28 a以上.在不同的土壤类型下,土壤有机碳含量的变化速率存在着一定的差异,平均有机...     

用常规净水工艺处理含盐矿井水的试验研究

本文对含放射性、氟化物、苯并(α)芘、硫酸盐、铁锰等超标复杂矿井水进行了试验研究,得出:在一定条件下用曝气、配水、混凝沉淀、过滤消毒等常规净水措施处理生活饮用水达标是可行的。     

《地震学刊》的刊徽设计

提出了刊徽设计的原则和要求。所设计的《地震学刊》的刊徽是个由经纬网格所构成的公转着的地球。经纬网格由ＳＪ两个字母和两条细线所组成。ＳＪ为《地震学刊》英文名和江苏的汉语拼音名的缩写。Ｓ表示大地震所激发的地球自由振动的一阶振型；两条细线既表示经线，又表示地球自由振动的基振型。     

Operating condition influences on PCDD/Fs emissions from sinter pot tests with hot flue gas recycling

This study was designed to clarify the influence of operating conditions on the formation and emissions of polychlorinated-pdibenzodioxins and dibenzofurans (PCDD/Fs) from a sintering process with hot flue gas recycling. A pilot scale sinter pot with simulated flue gas recycling was developed, and four key operational parameters, including temperature, oxygen content of the simulated waste flue gas, the coke rate of the sintering mixture, and the quicklime quality, were selected for exploring PCDD/Fs formation. The results showed that the temperature of the recycled flue gas had a major affect on PCDD/Fs formation, and a high temperature could significantly increase their formation during sintering. A clear linear correlation between the temperature of recycling flue gas and PCDD/Fs emission (r = 0.93) was found. PCDD/Fs could be reduced to a certain extent by decreasing the level of oxygen in the recycled flue gas, while sintering quality was unchanged. The coke rate had no significant influence on the formation of PCDD/Fs, but the quality of quicklime used in the sintering mixture could affect not only the amount of PCDD/Fs emissions but also the sintering productivity. Compared with a benchmark sinter pot test, PCDD/Fs emissions markedly decreased with improvements to quicklime quality. However, the reduction in PCDD/Fs emissions realized by using high-quality quicklime was limited by the temperature of the inlet gas. The highest reduction achieved was 51% compared with conventional quicklime when the temperature of the inlet gas was 150°C.     

Soil warming effect on net ecosystem exchange of carbon dioxide during the transition from winter carbon source to spring carbon sink in a temperate urban lawn

The significant warming in urban environment caused by the combined effects of global warming and heat island has stimulated widely development of urban vegetations. However, it is less known of the climate feedback of urban lawn in warmed environment. Soil warming effect on net ecosystem exchange (NEE) of carbon dioxide during the transition period from winter to spring was investigated in a temperate urban lawn in Beijing, China. The NEE (negative for uptake) under soil warming treatment (temperature was about 5℃ higher than the ambient treatment as a control) was -0.71 μmol/(m².sec), the ecosytem was a CO₂ sink under soil warming treatment, the lawn ecosystem under the control was a CO₂ source (0.13 μmol/(m².sec)), indicating that the lawn ecosystem would provide a negative feedback to global warming. There was no significant effect of soil warming on nocturnal NEE (i.e., ecosystem respiration), although the soil temperature sensitivity (Q₁₀) of ecosystem respiration under soil warming treatment was 3.86, much lower than that in the control (7.03). The CO₂ uptake was significantly increased by soil warming treatment that was attributed to about 100% increase of α (apparent quantum yield) and A_max (maximum rate of photosynthesis). Our results indicated that the response of photosynthesis in urban lawn is much more sensitive to global warming than respiration in the transition period.