Predicting environmental impacts is essential when performing an environmental assessment on urban transport planning. System dynamics (SD) is usually used to solve complex nonlinear problems. In this study, we utilized system dynamics (SD) to evaluate the environmental impacts associated with urban transport planning in Jilin City, China with respect to the local economy, society, transport, the environment and resources. To accomplish this, we generated simulation models comprising interrelated subsystems designed to utilize changes in the economy, society, road construction, changes in the number of vehicles, the capacity of the road network capacity, nitrogen oxides emission, traffic noise, land used for road construction and fuel consumption associated with traffic to estimate dynamic trends in the environmental impacts associated with Jilin's transport planning. Two simulation scenarios were then analyzed comparatively. The results of this study indicated that implementation of Jilin transport planning would improve the current urban traffic conditions and boost the local economy and development while benefiting the environment in Jilin City. In addition, comparative analysis of the two scenarios provided additional information that can be used to aid in scientific decision-making regarding which aspects of the transport planning to implement in Jilin City. This study demonstrates that our application of the SD method, which is referred to as the Strategic Environmental Assessment (SEA), is feasible for use in urban transport planning. 相似文献
In this study the frequencies of PM10 (as key urban pollutant) in 14 key environmental protection cities in northern China were analyzed. It follows that the PM10 concentration in the high-frequency period is higher with an extent 0.009–0.066 mg m−3 than in the low-frequency period of 2001–2002. Further the impacts of three kinds of dust events on the PM10 concentration in four cities (Beijing, Hohhot, Xi’an and Lanzhou) were explored. The results showed that different kinds of dust events have different influences on variation of PM10 concentration in these four cities. In Lanzhou and Hohhot, which are near the source areas of dust events, the contribution degree of these three dust events to the PM10 is: floating dust>dust storm>blowing dust. Whereas, in Beijing and Xi’an situated in dust event passing areas, the mean value of PM10 concentration is higher in blowing dust than in floating dust (no dust storm). In addition, the influences of dust events on PM10 concentration are different in the cities on different dust event paths. In Beijing and Hohhot (on the northern path), the high PM10 concentration is usually caused by blowing dust. But in both Lanzhou and Xi’an (on the western/northwestern path) the high PM10 pollution concentration is usually caused by floating dust. 相似文献
Municipal Solid Waste (MSW) management in China has been transitioning from a mixed collection and treatment system to a separated collection and treatment system. The continuous rise of MSW treatment capacity and the optimization of technology structure provided basic facility support for China to promote MSW separation at source. China preferred a four-type separation system. Regulated recycling should be enhanced to improve the efficiency and sustainability of recycling industry. As food waste is the main composition of MSW in China, 20%–30% of the food waste diversion and land application could maximize the comprehensive environmental performance. Incineration is to be the pillar technology in MSW separated treatment system in China. 相似文献
In smelting processes, a large amount of off-gas emission is often generated, which can cause serious environmental and plant hygiene problems if not properly treated. Off-gas cleaning systems extract and treat the hazardous emissions, and ensure that the smelter operation is in accordance with environmental and industrial hygiene regulations. To this end, it is paramount that a well-designed control structure be incorporated into the system. In this work a plantwide control design procedure is applied to an industrial nickel smelter furnace off-gas cleaning system. We first approach the problem by conducting a steady-state analysis based on a nonlinear model of the process, where the objective is to determine how to achieve safe, clean and economic operation in terms of energy consumption. Results reveal that a large amount of energy can be saved by controlling the temperature in the furnace freeboard at its upper bound (active constraint). For the same reason, the temperatures in the two louvers (active constraints) should be controlled at their respective upper bounds so to minimize air intake into the system. The selection of the “unconstrained” variable to be controlled is found by applying the self-optimizing control technique, and the results indicate that a small loss is acceptable when one of the manipulated variables is fixed at its nominal optimal operating point, a highly desirable choice from an operational viewpoint. The bottleneck of the system is identified as the fans' discharge pressures when we allow the feed rate as a degree of freedom. Furthermore, a design change consisting of the installation of an auxiliary air intake in the smelter furnace shows to be a very effective economic alternative to minimize energy consumption. A control structure is then designed where the issue is to keep pressures in the system well within the negative region by determining the configuration of the regulatory and supervisory control layers such that acceptable dynamic performance in face of known, deterministic disturbance is achieved. Nonlinear dynamic simulations are performed to validate the suggested control structure for both modes of operation in the original system and in the proposed design change. The results showed that both regulatory and supervisory designs should make use of the simplicity of decentralized PI control schemes associated with some cascaded configurations so as to boost the disturbance rejection capabilities of the system. 相似文献
Antibiotic resistance genes (ARGs) in urban rivers are a serious public health concern in regions with poorly planned, rapid development. To gain insights into the predominant factors affecting the fate of ARGs in a highly polluted urban river in eastern China, a total of 285 ARGs, microbial communities, and 20 physicochemical parameters were analyzed for 17 sites. A total of 258 unique ARGs were detected using high-throughput qPCR, and the absolute abundance of total ARGs was positively correlated with total organic carbon and total dissolved nitrogen concentrations (P < 0.01). ARG abundance and diversity were greatly altered by microbial community structure. Variation partitioning analysis showed that the combined effects of multiple factors contributed to the profile and dissemination of ARGs, and variation of microbial communities was the major factor affecting the distribution of ARGs. The disparate distribution of some bacteria, including Bacteroides from mammalian gastrointestinal flora, Burkholderia from zoonotic infectious diseases, and Zoogloea from wastewater treatment, indicates that the urban river was strongly influenced by point-source pollution. Results imply that microbial community shifts caused by changes in water quality may lead to the spread of ARGs, and point-source pollution in urban rivers requires greater attention to control the transfer of ARGs between environmental bacteria and pathogens.