Real-world in-use activity, fuel use, and emissions for nonroad construction vehicles: a case study for excavators

A study design was developed and demonstrated for deployment of a portable emission measurement system (PEMS) for excavators. Excavators are among the most commonly used vehicles in construction activities. The PEMS measured nitric oxide, carbon monoxide, hydrocarbons, carbon dioxide, and opacity-based particulate matter. Data collection, screening, processing, and analysis protocols were developed to assure data quality and to quantify variability in vehicle fuel consumption and emissions rates. The development of data collection procedures was based on securing the PEMS while avoiding disruption to normal vehicle operations. As a result of quality assurance, approximately 90% of the attempted measurements resulted in valid data. On the basis of field data collected for three excavators, an average of 50% of the total nitric oxide emissions was associated with 29% of the time of operation, during which the average engine speed and manifold absolute pressure were significantly higher than corresponding averages for all data. Mass per time emission rates during non-idle modes (i.e., moving and using bucket) were on average 7 times greater than for the idle mode. Differences in normalized average rates were influenced more by intercycle differences than intervehicle differences. This study demonstrates the importance of accounting for intercycle variability in real-world in-use emissions to develop more accurate emission inventories. The data collection and analysis methodology demonstrated here is recommended for application to more vehicles to better characterize real-world vehicle activity, fuel use, and emissions for nonroad construction equipment.     

Characterization of real-world activity, fuel use, and emissions for selected motor graders fueled with petroleum diesel and B20 biodiesel

Motor graders are a common type of nonroad vehicle used in many road construction and maintenance applications. In-use activity, fuel use, and emissions were measured for six selected motor graders using a portable emission measurement system. Each motor grader was tested with petroleum diesel and B20 biodiesel. Duty cycles were quantified in terms of the empirical cumulative distribution function of manifold absolute pressure (MAP), which is an indicator of engine load. The motor graders were operated under normal duty cycles for road maintenance and repair at various locations in Wake and Nash Counties in North Carolina. Approximately 3 hr of quality-assured, second-by-second data were obtained during each test. An empirical modal-based model of vehicle fuel use and emissions was developed, based on stratifying the data with respect to ranges of normalized MAP, to enable comparisons between duty cycles, motor graders, and fuels. Time-based emission factors were found to increase monotonically with MAP. Fuel-based emission factors were mainly sensitive to differences between idle and non-idle engine operation. Cycle average emission factors were estimated for road "resurfacing," "roading," and "shouldering" activities. On average, the use of B20 instead of petroleum diesel leads to a negligible decrease of 1.6% in nitric oxide emission rate, and decreases of 19-22% in emission rates of carbon monoxide, hydrocarbons, and particulate matter. Emission rates decrease significantly when comparing newer engine tier vehicles to older ones. Significant reductions in tailpipe emissions accrue especially from the use of B20 and adoption of newer vehicles.     

Estimation of septic tank setback distances based on transport of E. coli and F-RNA phages

Setback distances between septic tank systems and the shorelines of Lake Okareka, New Zealand were determined from model simulations for a worst-case scenario, using the highest hydraulic conductivity and gradient measured in the field, removal rates of the microbial indicators (Escherichia coli and F-RNA phages) determined from a column experiment, and maximum values of the design criteria for the disposal system, and assuming an absence of an unsaturated zone, a continuous discharge of the raw effluent from a failed or non-complying treatment system (both indicators at concentrations of 1x10(7) counts/100 ml) into the groundwater and no sorption of pathogens in the aquifer. Modelling results suggest that the minimal setback distances were 16 m to satisfy the New Zealand Recreational Water Quality Guidelines for E. coli <126 per 100 ml (Ministry for the Environment, 1999) and 48 m to meet the Drinking-Water Standards for New Zealand 2000 for enteric virus <1 per 100 l (Ministry of Health, 2000). These distances may be applicable for other lakeshores in pumice sand aquifers with groundwater velocities <7 m/day. Findings of laboratory column and batch experiments provided an insight into the microbial attenuation and transport processes in pumice sand aquifers. Bacterial removal was predominately through filtration (87-88%) and partially by die-off (12-13%), while viral removal was by both die-off (45%) and filtration (55%). In addition, microbial die-off in groundwater without aquifer material (i.e., free microbes) was much lower than die-off in groundwater with aquifer material (i.e., sorbed microbes) and contributed only 2-6% to the total removal. This implies that the setback distances estimated from die-off rates for the free microbes, determined in the laboratory without considering aquifer media and other removal processes, which are often reported in the literature, could be larger than necessary.     

中国降水量高度效应及全球升温对它的影响

利用中国气象中心160站点的实际观察资料,对中国半个世纪的降水变化进行了系统分析,发现中国的夏季降水量与海拔高度存在着很好的反相关关系;同时,全球升温使得降水量的高度效应增强,主要表现为高海拔降水量海拔效应明显增强,这主要是由全球升温引起环流系统增强所引起的.     

二级UASB厌氧工艺在制药废水中的应用

抗菌素制药污水复杂,其CODCr高达39000mgL,硫酸盐的浓度在6500mgL左右,常规工艺很难处理,山东某制药厂采用了二级厌氧工艺处理此类废水,取得了良好的处理效果和经济效益。     

基于Kaya方法的四个直辖市碳效率评价与比较

应用Kaya恒等式的计算方法对我国4个直辖市2005-2009年的碳效率进行了评价和比较分析,结果显示:4个直辖市碳效率的排序在2005-2009年间没有发生变化,4个城市的碳效率都处于上升态势。     

Linking China’s emissions trading pilot schemes

All seven emissions trading pilots in China operate independently. One challenge facing most of them is the low inclusion thresholds for enterprises and the few total covered emissions, which negatively influences the effects of the emissions trading systems (ETSs). Some pilot sites, such as Guangdong, Hubei, Tianjin and Beijing, have indicated their willingness to link their schemes with others. ETS linking could expand scheme coverages and therefore help to reduce the overall costs of achieving the linked schemes’ emissions control targets. Linking could also help to address the issues of carbon leakage and reduce price fluctuations. The potential benefits and feasibility of linking different pilot systems are analyzed in this article. The seven pilot regions are at different stages of social and economic development, with significant differences in total emissions and emissions structures as well as carbon abatement potentials and costs. Through linking, more-developed regions such as Beijing, Shanghai and Shenzhen, which are typically considered to face higher mitigation costs, will have the opportunity to achieve their emissions control targets by purchasing carbon units from less-developed regions, which will earn financial revenues from selling the units. To realize this win-win result, a series of policy and technical barriers at both the central government and pilot government levels needs to be overcome. Establishing a unified national emissions trading market would appear to be the ideal solution to these challenges, but it will take considerable time and will not be the short-term solution. In the absence of a unified national scheme, it is recommended that the central government encourage pilot schemes to link, that it develops corresponding national policies to support the linking efforts and that the pilot schemes that are intended to be linked coordinate on certain design elements. Based on the coordinating need, the major elements of an ETS can be divided into four categories: elements that need mutual recognition (cap setting and allowance allocation methods); elements that should be completely identical (compliance mechanisms, price containment measures, banking and borrowing rules, and offset mechanisms); technical elements that are preferably identical and easy to coordinate (MRV standards, technical registry standards); and elements that require no coordination (coverages and scopes).     

Application of hinokitiol potassium salt for wood preservative

The decay of wood and other cellulosic materials by fungi cause significant economic loss. The widely used chromated copper arsenate was prohibited for the environmental impact and safety of arsenic and chromium. It was found that natural product hinokitiol (HK) had fungicidal and insecticidal activities, and its toxicity was bearable for the environment. We described the practical synthesis of HK-K salt. According to the GB/T18261-2000 and LY/T1283-1998, wood preservative performance of HK-K salt was tested. The results showed that the best inhibitory concentration of HK-K salt was 50 mg/L, for which the prevention effectiveness on mold is better, the killed value is between 0 and 1, and the corrosion-resistant for wood-rotting fungi is grade A.     

A critical review on the application of biochar in environmental pollution remediation: Role of persistent free radicals (PFRs)

Biochar as an emerging carbonaceous material has exhibited a great potential in environmental application for its perfect adsorption ability. However, there are abundant persistent free radicals (PFRs) in biochar, so the direct and indirect PFRs-mediated removal of organic and inorganic contaminants by biochar was widely reported. In order to comprehend deeply the formation of PFRs in biochar and their interactions with contaminants, this paper reviews the formation mechanisms of PFRs in biochar and the PFRs-mediated environmental applications of biochar in recent years. Finally, future challenges in this field are also proposed. This review provides a more comprehensive understanding on the emerging applications of biochar from the viewpoint of the catalytic role of PFRs.