Review on the Effects of Combined Pollution of Lead and Chromium on Soil Microorganisms and Treatment Methods

Heavy metals—Pb and Cr are important causes of environmental pollution, and they often coexist in nature. At present, the effects of Pb and Cr toxicity on soil microorganisms have been less studied, in soil environment which is extremely complex. Simulating soil environment and studying microbial reaction under various heavy metal conditions are of great significance for revealing microbial tolerance to heavy metals. In this paper, firstly, the related concepts of soil rechecking pollution are discussed, and the physical and chemical properties and forms of lead and chromium are introduced accordingly. Secondly, the effects of combined pollution of lead and chromium on soil microbial biomass, soil microbial community structure and soil microbial activity were discussed. Finally, the relevant treatment methods of heavy metal contaminated soil were put forward.

Automatic Satisfaction Analysis in Call Centers Considering Global Features of Emotion and Duration

Analysis of customers＇ satisfaction provides a guarantee to improve the service quality in call centers.In this paper,a novel satisfaction recognition framework is introduced to analyze the customers＇ satisfaction.In natural conversations,the interaction between a customer and its agent take place more than once.One of the difficulties insatisfaction analysis at call centers is that not all conversation turns exhibit customer satisfaction or dissatisfaction. To solve this problem,an intelligent system is proposed that utilizes acoustic features to recognize customers＇ emotion and utilizes the global features of emotion and duration to analyze the satisfaction. Experiments on real-call data show that the proposed system offers a significantly higher accuracy in analyzing the satisfaction than the baseline system. The average F value is improved to 0. 701 from 0. 664.

Volatile organic compounds in wintertime North China Plain:Insights from measurements of proton transfer reaction time-of-flight mass spectrometer(PTR-ToF-MS)

The characteristics of wintertime volatile organic compounds(VOCs)in the North China Plain(NCP)region are complicated and remain obscure.VOC measurements were conducted by a proton transfer reaction time-of-flight mass spectrometer(PTR-ToF-MS)at a rural site in the NCP from November to December 2018.Uncalibrated ions measured by PTRToF-MS were quantified and the overall VOC compositions were investigated by combining the measurements of PTR-ToF-MS and gas chromatography-mass spectrometer/flame ionization detector(GC-MS/FID).The measurement showed that although atmospheric VOCs concentrations are often dominated by primary emissions,the secondary formation of oxygenated VOCs(OVOCs)is non-negligible in the wintertime,i.e.,OVOCs accounts for 42%±7%in the total VOCs(151.3±75.6 ppbV).We demonstrated that PTR-MS measurements for isoprene are substantially overestimated due to the interferences of cycloalkanes.The chemical changes of organic carbon in a pollution accumulation period were investigated,which suggests an essential role of fragmentation reactions for large,chemically reduced compounds during the heavy-polluted stage in wintertime pollution.The changes of emission ratios of VOCs between winter 2011 and winter 2018 in the NCP support the positive effect of“coal to gas”strategies in curbing air pollutants.The high abundances of some key species(e.g.oxygenated aromatics)indicate the strong emissions of coal combustion in wintertime of NCP.The ratio of naphthalene to C8 aromatics was proposed as a potential indicator of the influence of coal combustion on VOCs.