Role of illumination intensity in microcystin development using Microcystis aeruginosa as the model algae

Environmental Science and Pollution Research - Microcystis aeruginosa (M. aeruginosa) is one of the most common genera of cyanobacteria in algal blooms. In the present work, the impact of the...     

Factors influencing farmers’ decisions on nitrogen fertilizer application in the Liangzihu Lake basin,Central China

Overuse of nitrogen (N) fertilizers in agriculture activities has caused severe water pollution in China. The lack of data at producer level hampers decision makers in the development and implementation of efficient policies to curb excessive N-fertilizer use. In a survey of 300 farm households in the Liangzihu Lake basin, we identified factors associated with farmers’ decisions on N-fertilizer use and application rate. Household survey and multiple linear regression models indicate that the average application rate in the study region is 229 kg N ha^?1, which exceeds the recommended rate for maximum profit for cereal crops (maize, wheat, and rice) in China of 150–180 kg N ha^?1. High N-application rates are associated with low farmland productivity (coefficient = ?15.66, p = 0.02), a high share of off-farm income (coefficient = 27.14, p = 0.003), and a low education level of the household head (coefficient = ?10.83, p = 0.039). Neither physical infrastructure nor access to input markets appears to be related to N-application rates. It may be concluded that excessive use of N in agriculture of Central China is mainly a problem of insufficient awareness and high share of off-farm income.     

NOx emission calculations for bulk carriers by using engine power probabilities as weighting factors

An important marine pollution issue identified by the International Maritime Organization (IMO) is NO_x emissions; however, the stipulated method for determining the NO_x certification value does not reflect the actual high emission factors of slow-speed two-stroke diesel engines over long-term slow steaming. In this study, an accurate method is presented for calculating the NO_x emission factors and total amount of NO_x emissions by using the actual power probabilities of the diesel engines in four types of bulk carriers. The proposed method is suitable for all types and purposes of diesel engines, is not restricted to any operating modes, and is highly accurate. Moreover, it is recommended that the IMO-stipulated certification value calculation method be modified accordingly to genuinely reduce the amount of NO_x emissions. The successful achievement of this level of reduction will help improve the air quality, especially in coastal and port areas, and the health of local residents.

Implications: As per the IMO, the NO_x emission certification value of marine diesel engines having a rated power over 130 kW must be obtained using specified weighting factor (WF)-based calculation. However, this calculation fails to represent the current actual situation. Effective emission reductions of 6.91% (at sea) and 31.9% (in ports) were achieved using a mathematical model of power probability functions. Thus, we strongly recommend amending the certification value of NO_x Technical Code 2008 (NTC 2008) by removing the WF constraints, such that the NO_x emissions of diesel engines is lower than the Tier-limits at any load level to obtain genuine NO_x emission reductions.     

锰铜铈氧化物催化剂氧化NO性能及动力学研究

实验以TiO2为载体采用浸渍法制备CuOx/TiO2、CeOx/TiO2、CuCeOx/TiO2和MnCuCeOx/TiO2催化剂,考察这些催化剂氧化NO活性,探究Cu、Ce摩尔比和添加Mn元素对CuCeOx/TiO2催化剂氧化NO活性的影响,使用扫描电镜观察催化剂表面结构。研究发现,Cu、Ce元素配合后的CuCeOx/TiO2催化剂氧化活性明显好于单独含Cu、Ce的催化剂,当Cu、Ce摩尔比为Cu:Ce=1∶2时,CuCeOx/TiO2催化剂氧化活性最好,在NO浓度500×10-6,O210%,空速为24 000 h-1,350℃时,NO氧化度为0.62;添加Mn元素可以提高CuCeOx/TiO2催化剂低温氧化活性,250℃时,MnCuCe/Ti-3和MnCuCe/Ti-5催化剂氧化度为0.53和0.69,300℃时,MnCuCe/Ti-3和MnCuCe/Ti-5催化剂氧化度均为0.76;此外,实验还研究了NO在MnCuCe/Ti-3催化剂上反应的动力学方程。     

DO浓度对间歇曝气单级自养脱氮系统N2O排放的影响

以单级自养脱氮系统为研究对象,采用有效容积为15 L的SBBR反应器,系统进水NH+4-N浓度约为360 mg/L,控制温度为(30±2)℃,采用间歇曝气方式运行,曝气段DO浓度从2.4~2.6 mg/L逐渐下降到0.9~1.1 mg/L,研究了单级自养脱氮系统的脱氮性能与N2O排放情况。结果表明,反应器曝气段DO浓度从2.4~2.6 mg/L下降到0.9~1.1mg/L,系统TN去除率均达到80%,但在相同运行时间内的TN去除率依次降低,NH+4-N平均反应速率从0.19 mg/(L·min)降低至0.05 mg/(L·min),NO-3-N累计产生量稳定于14.9~16.5 mg/L,NO-2-N浓度在反应器内未产生明显的积累。随着曝气段DO浓度的下降,最大N2O释放速率逐渐降低,N2O累计释放量从73.8 mg下降到61.0 mg,N2O转化率介于2.4%~2.9%。     

Impacts of climate change in rapidly urbanizing region-a case study in Hangzhou(China)

Climate change is expected to be a major driving force of landscape in the coming decades.It will have a multitude of potential impacts that vary in intensity and effect according to region and sector.In the context of global warming,the climate of China has changed significantly in the recent 100 years.The reason for climate change in China is mainly due to irrational land use caused by human activities,which chiefly results in the rapid industrialization and urbanization process.Based on an assessment model,this research represents a picture of the impacts of climate change in six districts of Hangzhou region.The aim of this paper is to conclude,on the one hand,some of Hangzhou sensitivities in relation to the primary effects of climate change.On the other hand,a reflection is made on a methodology to formulate preconditions on a scientific basis for further research by design of integrated adaptation options for the future spatial developments in function to upgrade Hangzhou resilience in relation to climate change challenges.     

Generation of solid wastes in typhoon disasters and their emergent cleaning and treatment means

In Taiwan, typhoons usually result in a large amount of waste that needs to be removed in a short time from July to October. This study reviewed the relevant regulations on the clean-up of typhoon waste, including emergency response regulations, organizations and information systems; and we also discuss different typhoon waste clean-up and disposal methods. The results indicate that the parameters other than the maximum wind speed, such as the maximum accumulated rainfall, flooded area, waste output, sludge output, disinfected area and government dispatched attendance reached statistical significance (p < 0.05). Waste, tree branches and bird carcasses were primarily incinerated, while silt and building materials were buried, and pig and cattle carcasses were placed in a landfill with the tertiary treatment of wastewater. This study also reports on the relevant regulations for prevention of epidemics among personnel working in disaster areas. The results can provide important references for the disposal of typhoon waste in developing countries. As Asian countries have similar life styles and are often attacked by typhoons, the results of this study provide Asian countries with the operating experience of Taiwan in emergency treatment of solid waste resulting from typhoons as a reference for them to plan response systems and operation.     

Concentration and health risk evaluation of heavy metals in market-sold vegetables and fishes based on questionnaires in Beijing,China

Concentrations of heavy metals (As, Cd, Pb, Cu, Ni, Fe, Mn, and Zn) in market vegetables and fishes in Beijing, China, are investigated, and their health risk to local consumers is evaluated by calculating the target hazard quotient (THQ). The heavy metal concentrations in vegetables and fishes ranged from not detectable (ND) to 0.21 mg/kg fresh weight (f.w.) (As), ND to 0.10 mg/kg f.w. (Cd), and n.d to 0.57 mg/kg f.w. (Pb), with average concentrations of 0.17, 0.04, and 0.24 mg/kg f.w., respectively. The measured concentrations of As, Cd, Pb, Cu, Ni, Fe, Mn, and Zn are generally lower than the safety limits given by the Chinese regulation safety and quality standards of agriculture products (GB2762-2012). As, Cd, and Pb contaminations are found in vegetables and fishes. The exceeding standard rates are 19 % for As, 3 % for Cd, and 25 % for Pb. Pb contaminations are found quite focused on the fish samples from traditional agri-product markets. The paper further analyzed the health risk of heavy metals in vegetables and fishes respectively from supermarkets and traditional agri-product markets; the results showed that the fishes of traditional agri-product markets have higher health risk, while the supermarkets have vegetables of higher heavy metal risk, and the supervision should be strengthened in the fish supply channels in traditional agri-product markets.     

铁碳微电解-Fenton法预处理苯胺基乙腈生产废水的动力学研究

通过采用铁碳微电解-Fenton法预处理苯胺基乙腈生产废水的实验研究,分析了处理过程的COD降解动力学;同时研究了单纯活性炭吸附和微电解过程中COD去除率的变化。结果表明,铁碳微电解的初期COD降解过程近似符合一级反应动力学,并且得到微电解与活性炭吸附对铁碳微电解降解COD的关系式;Fenton反应中通过研究有机物浓度和过氧化氢初始浓度与反应进程的关系,建立了反应动力学模型;单纯吸附实验COD去除率在24h内快速下降,而微电解在相应时间内COD去除率波动较小,为实际应用提供了数据经验和理论依据。     

基于白碳黑的水化硅酸钙制备及其磷回收特性简

以白碳黑、硅灰、硅藻土和硅胶筛选硅质原料,并与钙质原料电石渣制备了水化硅酸钙。借助XRF、BET、FTIR等表征手段,通过多次重复除磷实验,研究了硅质原料特性对水化硅酸钙回收磷性能的影响。结果表明,白碳黑具有极高的反应活性,因此可作为制备具有磷回收特性的水化硅酸钙的硅质原料。结合XRD等表征发现,白碳黑的有效利用率是影响水化硅酸钙回收磷性能的关键,该利用率取决于白碳黑与电石渣的摩尔配比以及水热反应温度。当电石渣与白碳黑的摩尔比为1.6：1,反应温度为170℃时,白碳黑具有最佳的利用效率。该条件制备的水化硅酸钙可作为晶种,在其表面结晶形成羟基磷灰石,从而达到磷回收的目的,磷回收后固体物质中的磷含量为19.05%。