In this study, radon-222 concentrations were measured within 34 houses distributed in the northern, southern, and central areas of the city of Querétaro in 2007. The objective of this study was to establish the s...In this study, radon-222 concentrations were measured within 34 houses distributed in the northern, southern, and central areas of the city of Querétaro in 2007. The objective of this study was to establish the spatial distribution of radon with respect to geological faults and its relation to certain environmental variables. For each sampling site, the radon-222 concentration was analyzed as a function of various climate variables, relative humidity, temperature, and atmospheric pressure, in addition to the ventilation of the house and distance of each site from any geological faults in the area. A multivariate statistical technique was used to analyze these variables based on two components. For component 1, the relative humidity and temperature had the greatest weight, 0.677 and 0.492, respectively, while for component 2, the greatest weights corresponded to radon and the temperature with 0.693 and 0.609, respectively. The average radon concentration across the entire sampling period was 38.92 Bq/m3, the minimum detected value was 6.01 Bq/m3?for site 91GAG0607, and the maximum detected value was 225.95 Bq/m3?for site 91CAM20907. This last value is outside the standards permitted by the Environmental Protection Agency of the United Stated, which is 148 Bq/m3?for indoor environments. With respect to geological faults and their relationship to radon-222, the concentrations for the sampling sites had no relationship to the closeness or distance to these faults.展开更多
Anaerobic oxidation of methane(AOM)can contribute to reducing methane emissions in landfills;however,the AOM rates vary depending on the inoculum source.This study addressed the capacity of AOM of a fermentative micro...Anaerobic oxidation of methane(AOM)can contribute to reducing methane emissions in landfills;however,the AOM rates vary depending on the inoculum source.This study addressed the capacity of AOM of a fermentative microbial community derived from a reactor treatingmunicipal solidwastes.First,the inoculum’s autotrophic capacitywas verified using a gasmixture of 75% CO_(2) and 25% H_(2).Results demonstrated that the fermentative microbial community reached amaximum CO_(2) consumption rate of 22.5±1.2 g CO_(2)/(m^(3)·h),obtaining acetate as the main product.Then,the inoculum was grown on a gas mixture of 50%CH_(4),35%CO_(2),and 15%N_(2),using iron(Fe^(3+))as the electron acceptor.The AOM rates increased over time and peaked at 3.1±0.9 g CH_(4)/(m^(3)·h)by 456 h with the simultaneous consumption of CO_(2).Acetate was the main product,with amaximum concentration of 180±9mg/L.By 408 h,a bacterial cluster of indicator species correlated with the AOM rates,including to Rhodobactereceae(r=0.80),Oceanicola(r=0.80),Propionicicella(r=0.77),Christensenellaceae(r=0.58),Oscillospiraceae(r=0.53),Mobilitalea(r=0.66),Hungateiclostridiaceae(r=0.46),and Izemoplasmatales(r=0.77).Methanosarcina,Methanobacterium,and Methanoculleus correlated with the AOM and CO_(2) consumption rates.A co-occurrence network analysis showed that Methanosarcina positively interacted with syntrophic bacteria like Christensenellaceae and Acinetobacter and diverse heterotrophic bacteria.This study demonstrated the feasibility of obtaining a CH_(4)-oxidizing microbial community in 16 days,exhibiting AOM rates higher than those reported for soils.展开更多
The combined application of organic manure and chemical fertilizers is an effective way to enhance soil organic carbon(SOC)sequestration through its influences on organic carbon(OC)input and the stability of SOC fract...The combined application of organic manure and chemical fertilizers is an effective way to enhance soil organic carbon(SOC)sequestration through its influences on organic carbon(OC)input and the stability of SOC fractions.However,there is limited information on the carbon sequestration efficiency(CSE)of chemically separated SOC fractions and its response to OC input under long-term fertilization regimes,especially at different sites.This study used three long-term fertilization experiments in Gongzhuling,Zhengzhou and Qiyang spanning 20 years to compare the stocks and CSE in four different OC fractions(very labile OC,labile OC,less labile OC,and non-labile OC)and their relationships with annual OC input.Three treatments of no fertilization(CK),chemical nitrogen,phosphorous,and potassium fertilizers(NPK),and chemical NPK combined with manure(NPKM)were employed.The results showed that compared with CK,NPKM resulted in enhanced SOC stocks and sequestration rates as well as CSE levels of all fractions irrespective of experimental site.Specifically for the very labile and non-labile OC fractions,NPKM significantly increased the SOC stocks by 43 and 83%,77 and 86%,and 73 and 82%in Gongzhuling,Qiyang,and Zhengzhou relative to CK,respectively.However,the greatest changes in SOC stock relative to the initial value were associated with non-labile OC fractions in Gongzhuling,Zhengzhou,and Qiyang,which reached 6.65,7.16,and 7.35 Mg ha^(-1) under NPKM.Similarly,the highest CSE was noted for non-labile OC fractions under NPKM followed sequentially by the very labile OC,labile OC,and less-labile OC fractions,however a CSE of 8.56%in the non-labile OC fraction for Gongzhuling was higher than the values of 6.10 and 4.61%in Zhengzhou and Qiyang,respectively.In addition,the CSE for the passive pool(very labile+labile OC fractions)was higher than the active pool(less-labile+non-labile OC fractions),with the highest value in Gongzhuling.The redundancy analysis revealed that the CSEs of fractions and pools were negatively influenced by annual OC input,mean annual precipitation and temperature,but positively influenced by the initial SOC and total nitrogen contents.This suggests that differential stability of sequestered OC is further governed by indigenous site characteristics and variable amounts of annual OC input.展开更多
This paper reviews the importance of visibility in public deliberation in the theoretical construction of political communication. Political communication is the area that study social and political interactions of ac...This paper reviews the importance of visibility in public deliberation in the theoretical construction of political communication. Political communication is the area that study social and political interactions of actors through discourses and practices within the public sphere. The social and political actors manage their public appearances in an exercise of visibility, allowing deliberation of public affairs. In recent years, Mexico has been a relevant case of study for understanding the opening of media into the public discussion of governmental affairs. As an example, this paper presents an analysis of public deliberation in the city of Quer6taro, Mexico. This study analyses political participation and openness of media, based on the concepts visibility, public sphere and citizenship. The analysis was built on the idea that the press concentrates most of the issues of public interest and that it reflects actors and arguments given for deliberation. In a qualitative approximation, we analyzed the discourses published in four journals and developed an analytical framework that illustrates the levels of access and visibility of a variety of political and social actors. This exercise demonstrates the importance of the concept of visibility in public deliberation and the media as managers in the current configuration of political communication.展开更多
基金partially supported by Dirección General de Asuntos Académicos,Universidad Nacional Autónoma de México,Projects PAPIIT IN114806 and PAPIIT IN120808.
文摘In this study, radon-222 concentrations were measured within 34 houses distributed in the northern, southern, and central areas of the city of Querétaro in 2007. The objective of this study was to establish the spatial distribution of radon with respect to geological faults and its relation to certain environmental variables. For each sampling site, the radon-222 concentration was analyzed as a function of various climate variables, relative humidity, temperature, and atmospheric pressure, in addition to the ventilation of the house and distance of each site from any geological faults in the area. A multivariate statistical technique was used to analyze these variables based on two components. For component 1, the relative humidity and temperature had the greatest weight, 0.677 and 0.492, respectively, while for component 2, the greatest weights corresponded to radon and the temperature with 0.693 and 0.609, respectively. The average radon concentration across the entire sampling period was 38.92 Bq/m3, the minimum detected value was 6.01 Bq/m3?for site 91GAG0607, and the maximum detected value was 225.95 Bq/m3?for site 91CAM20907. This last value is outside the standards permitted by the Environmental Protection Agency of the United Stated, which is 148 Bq/m3?for indoor environments. With respect to geological faults and their relationship to radon-222, the concentrations for the sampling sites had no relationship to the closeness or distance to these faults.
基金This work was supported by the DGAPA-UNAM(PAPIIT project,No.IN102721)the support from CONAHCYT through the Investigadoras e Investigadores por Mexico program(Researcher ID 6407,Project 265).
文摘Anaerobic oxidation of methane(AOM)can contribute to reducing methane emissions in landfills;however,the AOM rates vary depending on the inoculum source.This study addressed the capacity of AOM of a fermentative microbial community derived from a reactor treatingmunicipal solidwastes.First,the inoculum’s autotrophic capacitywas verified using a gasmixture of 75% CO_(2) and 25% H_(2).Results demonstrated that the fermentative microbial community reached amaximum CO_(2) consumption rate of 22.5±1.2 g CO_(2)/(m^(3)·h),obtaining acetate as the main product.Then,the inoculum was grown on a gas mixture of 50%CH_(4),35%CO_(2),and 15%N_(2),using iron(Fe^(3+))as the electron acceptor.The AOM rates increased over time and peaked at 3.1±0.9 g CH_(4)/(m^(3)·h)by 456 h with the simultaneous consumption of CO_(2).Acetate was the main product,with amaximum concentration of 180±9mg/L.By 408 h,a bacterial cluster of indicator species correlated with the AOM rates,including to Rhodobactereceae(r=0.80),Oceanicola(r=0.80),Propionicicella(r=0.77),Christensenellaceae(r=0.58),Oscillospiraceae(r=0.53),Mobilitalea(r=0.66),Hungateiclostridiaceae(r=0.46),and Izemoplasmatales(r=0.77).Methanosarcina,Methanobacterium,and Methanoculleus correlated with the AOM and CO_(2) consumption rates.A co-occurrence network analysis showed that Methanosarcina positively interacted with syntrophic bacteria like Christensenellaceae and Acinetobacter and diverse heterotrophic bacteria.This study demonstrated the feasibility of obtaining a CH_(4)-oxidizing microbial community in 16 days,exhibiting AOM rates higher than those reported for soils.
基金support from the National Natural Science Foundation of China(42177341)is highly acknowledged。
文摘The combined application of organic manure and chemical fertilizers is an effective way to enhance soil organic carbon(SOC)sequestration through its influences on organic carbon(OC)input and the stability of SOC fractions.However,there is limited information on the carbon sequestration efficiency(CSE)of chemically separated SOC fractions and its response to OC input under long-term fertilization regimes,especially at different sites.This study used three long-term fertilization experiments in Gongzhuling,Zhengzhou and Qiyang spanning 20 years to compare the stocks and CSE in four different OC fractions(very labile OC,labile OC,less labile OC,and non-labile OC)and their relationships with annual OC input.Three treatments of no fertilization(CK),chemical nitrogen,phosphorous,and potassium fertilizers(NPK),and chemical NPK combined with manure(NPKM)were employed.The results showed that compared with CK,NPKM resulted in enhanced SOC stocks and sequestration rates as well as CSE levels of all fractions irrespective of experimental site.Specifically for the very labile and non-labile OC fractions,NPKM significantly increased the SOC stocks by 43 and 83%,77 and 86%,and 73 and 82%in Gongzhuling,Qiyang,and Zhengzhou relative to CK,respectively.However,the greatest changes in SOC stock relative to the initial value were associated with non-labile OC fractions in Gongzhuling,Zhengzhou,and Qiyang,which reached 6.65,7.16,and 7.35 Mg ha^(-1) under NPKM.Similarly,the highest CSE was noted for non-labile OC fractions under NPKM followed sequentially by the very labile OC,labile OC,and less-labile OC fractions,however a CSE of 8.56%in the non-labile OC fraction for Gongzhuling was higher than the values of 6.10 and 4.61%in Zhengzhou and Qiyang,respectively.In addition,the CSE for the passive pool(very labile+labile OC fractions)was higher than the active pool(less-labile+non-labile OC fractions),with the highest value in Gongzhuling.The redundancy analysis revealed that the CSEs of fractions and pools were negatively influenced by annual OC input,mean annual precipitation and temperature,but positively influenced by the initial SOC and total nitrogen contents.This suggests that differential stability of sequestered OC is further governed by indigenous site characteristics and variable amounts of annual OC input.
文摘This paper reviews the importance of visibility in public deliberation in the theoretical construction of political communication. Political communication is the area that study social and political interactions of actors through discourses and practices within the public sphere. The social and political actors manage their public appearances in an exercise of visibility, allowing deliberation of public affairs. In recent years, Mexico has been a relevant case of study for understanding the opening of media into the public discussion of governmental affairs. As an example, this paper presents an analysis of public deliberation in the city of Quer6taro, Mexico. This study analyses political participation and openness of media, based on the concepts visibility, public sphere and citizenship. The analysis was built on the idea that the press concentrates most of the issues of public interest and that it reflects actors and arguments given for deliberation. In a qualitative approximation, we analyzed the discourses published in four journals and developed an analytical framework that illustrates the levels of access and visibility of a variety of political and social actors. This exercise demonstrates the importance of the concept of visibility in public deliberation and the media as managers in the current configuration of political communication.
