Conversion Margins for the Major Uses of Agricultural Land and Their Variations in Shandong Province, China

It is of practical significance for the decision-making on country food security and farmland protection to analyze the conversion margins for the major uses of agricultural land and their variations. Based on the panel data of wheat, corn, vegetable, fruit, and forests productions from 520 investigated farmer households of 13 investigated villages in Shandong Province from 2003 to 2009, and using Cobb-Douglas production function, the revenue conversion margins can be obtained separately, between different grain-crops (wheat, corn) and different non-grain crops (vegetable, fruit, forests), and the conversion relationship between growing grain( wheat, corn) and going out for non-farm work. The results show that from 2003 to 2009, growing wheat and corn are more economically and reasonably for farmers, compared with growing vegetable, but growing wheat and corn are becoming less economically and less reasonably day by day, compared with planting forests. Moreover, the conversion margin between wheat and fruit shows obvious scissors difference. Just from 2007, farmers’ growing fruit became economically and reasonably, but until 2009, compared with going out to work after abandoning farm8land, growing wheat had no economic rationality. From 2003 to 2009, farmers’ growing corn is more profitable than growing fruit and going out for non-farm work after abandoning farmland. The subsidies for wheat and corn have increased farmers’ comparative income from food production remarkably, but the subsidies cannot change the general tendency that farmers transform food (wheat, corn) production into non-food (especially forests) production. The revenue difference between growing wheat, corn and vegetable and growing fruit and forests is being pulled ceaselessly bigger, and the tendency that farmers transform wheat, corn and vegetable growing lands into fruit and forests growing lands has become increasingly apparent.     

坡耕地与林地价值比较研究--兼论退耕还林的效益

本文从坡耕地与林地价值差异入手，认识和界定耕地与林地的价值，运用经济学理论分析评价退耕土地的前后价值变化，探讨退耕还林工程产生的生态、经济和社会效益，为国家制定退耕还林政策提供一些建议。     

某生活垃圾卫生填埋场填埋作业区覆膜抽气除臭试验研究

本文采用三种不同的覆膜抽气模式对填埋场作业面进行除臭试验研究,结果表明:覆膜1.0mm+3台负压车、2条负压管比单层覆膜0.3mm+1台负压抽气车、2条临负压管或覆膜0.3mm+3台负压车对氨气、硫化氢和臭气浓度的去除效果都要更好;但覆膜抽气法对总挥发性有机物(Total Volatile Organic Compounds,TVOC)的去除效果较之前更差,这主要是由于TVOC主要为分子量较大的有机物,扩散较慢,且垃圾堆体在厌氧条件下产生的TVOC浓度更高。     

Ammonia in urban atmosphere can be substantially reduced by vehicle emission control: A case study in Shanghai, China

To investigate the impact of emission controls on ammonia (NH₃) pollution in urban atmosphere, observation on NH₃ (1 hr interval) was performed in Shanghai before, during and after the 2019 China International Import Expo (CIIE) event, along with measurements on inorganic ions, organic tracers and stable nitrogen isotope compositions of ammonium in PM_2.5. NH₃ during the CIIE period was 6.5±1.0 µg/m³, which is 41% and 32% lower than that before and after the event, respectively. Such a decrease was largely ascribed to the emission controls in nonagricultural sources, of which contribution for measured NH₃ in control phase abated by ∼20% compared to that during uncontrol period. Molecular compositions of PAHs and hopanes further suggested a dominant role of the reduced vehicle emissions in the urban NH₃ abatement during the CIIE period. Our results revealed that vehicle exhaust emission control is an effective way to mitigate NH₃ pollution and improve air quality in Chinese urban areas.     

地表水中氨氮和总氮的相关性分析

为了解地表水中氨氮和总氮之间的相关关系,通过2010年濮阳市6个监测点位地表水的氨氮和总氮的监测数据,分析了氨氮和总氮之间的相关性,结果表明:地表水氨氮和总氮两个监测因子之间的相关关系为冬季最好R为0.9270,春、秋其次R分别为0.8980和0.8695,最后是夏季为0.6780。氨氮和总氮之间的比例系数波动范围较大为0.040～1.138,各不同季节的平均值为0.38。     

Ammonia volatilization from a Chinese cabbage field under different nitrogen treatments in the Taihu Lake Basin, China

Ammonia(NH_3) volatilization is a major pathway of nitrogen(N) loss from soil-crop systems.As vegetable cultivation is one of the most important agricultural land uses worldwide,a deeper understanding of NH_3 volatilization is necessary in vegetable production systems.We therefore conducted a 3-year(2010–2012) field experiment to characterize NH_3 volatilization and evaluate the effect of different N fertilizer treatments on this process during the growth period of Chinese cabbage.Ammonia volatilization rate,rainfall,soil water content,p H,and soil NH_4~+were measured during the growth period.The results showed that NH_3 volatilization was significantly and positively correlated to topsoil p H and NH4+concentration.Climate factors and fertilization method also significantly affected NH_3 volatilization.Specifically,organic fertilizer(OF) increased NH_3 volatilization by 11.77%–18.46%,compared to conventional fertilizer(CF,urea),while organic–inorganic compound fertilizer(OIF) reduced NH_3 volatilization by 8.82%–12.67% compared to CF.Furthermore,slow-release fertilizers had significantly positive effects on controlling NH_3 volatilization,with a 60.73%–68.80% reduction for sulfur-coated urea(SCU),a 71.85%–78.97% reduction for biological Carbon Power~#174; urea(BCU),and a 77.66%–83.12% reduction for bulk-blend controlled-release fertilizer(BBCRF)relative to CF.This study provides much needed baseline information,which will help in fertilizer choice and management practices to reduce NH_3 volatilization and encourage the development of new strategies for vegetable planting.     

微藻热化学转化制取生物质油催化剂的研究进展

微藻生物质能源被认为是可以有效解决能源危机的第三代生物质能源。以微藻为原料,通过热化学转化的方法制取生物质油是微藻能源利用的研究热点。综述了微藻热化学转化中催化剂的研究进展,包括碱金属盐催化剂、分子筛催化剂、过渡金属催化剂等,并提出了该研究的发展方向。     

MMT对汽油机催化前后微粒排放的影响

在一台自然吸气式PFI汽油机上,开展了甲基环戊二烯三羰基锰(MMT)汽油添加剂对发动机催化前后微粒数量浓度分布、粒径分布和质量浓度分布影响的试验,并研究了不同MMT含量对催化器催化效率的影响.结果表明,随着汽油添加剂MMT含量的增加,催化前后核态和积聚态的数量浓度均增加,MMT含量为12.5 mg·L-1和17.5 mg·L-1的燃油增加显著,相对于超细微粒,经催化器后细微粒和大微粒降幅比较明显.催化前后核膜态峰值粒径基本不变,催化后的积聚态峰值粒径明显大于催化前.随着MMT含量的增加,催化后积聚态峰值粒径向催化前移动.相比于基础油,随着MMT含量的增加,催化器对总数量浓度的催化效率有所降低,但MMT的增加大幅度提高了催化器对微粒总质量浓度的催化效率.     

Can further mitigation of ammonia emissions reduce exceedances of particulate matter air quality standards?

Several studies point out the importance of agricultural emissions to particulate matter (PM) concentrations, and particularly of NH₃ emissions to PM_2.5. Our study used three different chemical transport models (CHIMERE, EMEP and LOTOS-EUROS) to quantify the reductions of PM_2.5 and PM₁₀ concentrations due to reductions of NH₃ emissions beyond the Gothenburg Protocol (GP), as well as due to the GP alone compared to 2009. Simulations of PM_2.5 and PM₁₀ concentrations using 2009 meteorology were undertaken for five emission scenarios: 2009 emissions (as the reference simulation), GP emissions in 2020, and further 10%, 20% and 30% NH₃ emission reductions in EU27 beyond the GP. The modelling results for the scenarios with further 10%, 20% and 30% NH₃ agriculture emission reductions in EU27 beyond the GP show that the reduction achieved in PM concentrations is not linear with the emission reductions. In fact, the results from the study show that the impact of ammonia emissions reduction is significantly more efficient when the emission reduction rises. Moreover, based on the evaluation on 2009, the modelling study shows that the expected impact of ammonia emissions on the formation of particulate ammonium was underestimated by all models. This would imply that the role of ammonia on PM concentration and exceedances of PM_2.5 and PM₁₀ limit values is likely to be even larger than quantified in this study. This study shows that the implementation of the emission reductions imposed by the revised GP for 2020 will not suffice to achieve compliance with PM limit values everywhere in Europe; hence further European and local measures may be considered. NH₃ emissions from agriculture can be further reduced with the implementation of proven and feasible measures (substitution of fertilizers, improved storage of manure, way fertilizer injections, etc., …), in order to reduce PM concentrations and their impacts on human health across Europe.