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Microcystis development in most temperate lakes shows an annual cycle that is mainly triggered by water temperature and includes four stages. This study aims to identify the optimum growth temperature and the temperature thresholds for recruitment and overwintering in Microcystis in Lake Taihu, based on field data and experiments at the cellular and genetic level on Microcystis under a simulated temperature condition. The field investigation showed that the cyanobacterial biomass began to increase at 11-15 °C in spring, reached a peak at 20-30 °C and remained at a low level after the water temperature declined below 6 °C. The simulation experiment found that the recovery of gene expression, photosynthesis and growth in Microcystis cells occurred at 11-14 °C and increased to an appreciable level after the temperature exceeded 20 °C. Microcystis cells stopped growing and maintained low photosynthetic activity and gene expression when the temperature declined to 10 °C or lower. These results suggest that Microcystis in Lake Taihu begin recruitment at 11-14 °C in spring and grow vigorously at 20-30 °C, then overwinter at 10 °C or lower in winter.

Abstract Methane is responsible for 20% of the global warming resulting from greenhouse gas emissions. Municipal solid waste (MSW) landfills are the third largest anthropogenic source of methane and are thus important to estimating the global methane budget and evaluating its contribution to global greenhouse gas emissions. Based on the greenhouse gas inventory guidelines from the Intergovernmental Panel on Climate Change (IPCC) and the first-order decay method used to estimate emissions from MSW landfills – and in line with MSW management in various regions – we calculated methane emissions from MSW landfills in various Chinese provinces from 2003 to 2013. During this period, methane emissions from MSW landfills increased from 1141.10 Gg to 1858.98 Gg, representing a mean annual increase of 71.79 Gg. MSW emissions tended to increase more in the northern and western provinces than in the southern and eastern provinces, as methane emissions strongly and positively correlated with population and socioeconomic demographics. MSW decontamination is growing rapidly in China, and landfills predominate in all MSW treatments; moreover, incineration has also dramatically increased in recent years.

Hot flue gas evaporation technology is an effective strategy for zero liquid discharge of desulfurization wastewater. However, there is a potential risk that heavy metals such as Hg may be released from the wastewater during evaporation, disrupting the original balance of the power plant or even exceeding the Hg emission standard. Wastewater evaporation and Hg release behavior were obtained using a single droplet drying system. At an evaporation temperature of 300 °C, approximately 18.5% of Hg was released in the constant wet-bulb temperature period, and the remaining was released in the following evaporation periods. Furthermore, a fixed-bed experiment, in combination with density functional theory calculations, was used to investigate the possible migration mechanisms of released Hg. The results revealed that high HCl concentration, introduced fly ash, and precipitated evaporation products play a crucial role in the fate of Hg, and 85.3% of Hg finally turned into less harmful particulate-bound Hg. This study provides a new and effective strategy for evaluating the migration process of pollutants in wastewater treatment. Moreover, it will serve as an essential reference for advanced wastewater treatment and heavy metals control technologies in the future.

Abstract A waste heat air drying system, including a top closed air drying cycle and a bottom organic Rankine cycle (ORC), is proposed, considering the temperature matches during the humid air sensible heat and latent heat recovery processes. In the top air cycle, the waste heat is used as heat source. In the bottom ORC, the sensible heat and latent heat in the humid air of the top cycle are recovered to generate power and get rid of the moisture. The results showed two key parameters, including the working composition and the evaporating pressure of the bottom ORC, influence thermal matching of the humid air waste heat recovering process, and then on overall energy saving performance of the proposed system significantly. Using the zeotropic mixtures as working fluids of the bottom ORC is a better way with the air relative moisture content lower than 0.2, compared to that of using pure working fluids. While, using the pure working fluid is better with the air relative moisture content over 0.2. The optimal evaporating pressure of the bottom ORC is obtained, to achieve the maximal specific net power output and total thermal efficiency of the drying system.

Abstract Detailed estimates of carbon dioxide emissions at fine spatial scales are critical to both modelers and decision makers dealing with global warming and climate change. Globally, traffic-related emissions of carbon dioxide are growing rapidly. This paper presents a new method based on a multiple linear regression model to disaggregate traffic-related CO2 emission estimates from the parish-level scale to a 1 × 1 km grid scale. Considering the allocation factors (population density, urban area, income, road density) together, we used a correlation and regression analysis to determine the relationship between these factors and traffic-related CO2 emissions, and developed the best-fit model. The method was applied to downscale the traffic-related CO2 emission values by parish (i.e. county) for the State of Louisiana into 1-km2 grid cells. In the four highest parishes in traffic-related CO2 emissions, the biggest area that has above average CO2 emissions is found in East Baton Rouge, and the smallest area with no CO2 emissions is also in East Baton Rouge, but Orleans has the most CO2 emissions per unit area. The result reveals that high CO2 emissions are concentrated in dense road network of urban areas with high population density and low CO2 emissions are distributed in rural areas with low population density, sparse road network. The proposed method can be used to identify the emission “hot spots” at fine scale and is considered more accurate and less time-consuming than the previous methods.

Abstract As the state is vigorously promoting the construction of new urbanization in China, it is of great practical significance to study the interaction between urbanization, economic growth, and environmental pollution in three directions for the scientific planning of urbanization. Based on panel data of 30 provinces and cities in China during 2006–2015, we built the “Urbanization economic growth model” and a “simultaneous equation model.” The results show that urbanization promotes economic growth through the accumulation of physical capital, knowledge capital, and human capital; that the relationship between economic growth and urbanization is a benign interaction; that environmental pollution has a significant inhibitory effect on urbanization; and that there is an environmental Kuznets inverted U curve between economic growth and environmental pollution, and between urbanization and environmental pollution. On this basis, this paper puts forward some policy suggestions on how to enhance the positive interaction between urbanization and economic growth and promote the construction of new green urbanization.

Abstract Widespread adoption of electric vehicles is limited by their mileage, which is severely shortened by the positive temperature coefficient (PTC) heater in cold weather. To alleviate this difficulty, an electric vehicle thermal management system (EVTMS) with waste heat recovery from motor and controller unit is presented in this study. Utilizing a simulation model, the performances of EVTMS are investigated from the aspects of energy, exergy, and thermo-economy. In addition, the effects of waste heat amount and condensation temperature on EVTMS performances are exposed and discussed. It is indicated that increasing waste heat amount and decreasing condensation temperature would contribute to EVTMS performance improvement. Results show that the EVTMS with waste heat recovery leads to, in the best case, the coefficient of performance (COP) increase of 13.2%, the exergy destruction reduction of 20.01%, and the driving mileage improvement of 33.64%. With the waste heat varying in 0–2 kW and condensation temperature varying in 30–45 °C, the COP ranges from 2.05 to 4.71 and the system exergy efficiency varies in 28.63%~40.05%. Compared with the PTC heater, EVTMS with waste heat recovery could save the annual operation cost of 162.31–249.44 €. Base on the operation cost savings, the payback period of EVTMS ranges from 4.57 to 6.77 years.

The emission of condensable particulate matter (CPM) and its environmental impacts are arousing concern in China with the effective control of filter particulate matter (FPM). This study established an up-to-date and unit-based CPM emission inventory for industrial sectors and systematically evaluated the effects of CPM on primary and secondary PM2.5 in China. In 2020, the national CPM emissions total for industrial sectors was estimated to be 0.98 Tg with uncertainty from -49% to 66%, including 0.62 Tg of organic CPM (CPMorg) and 0.36 Tg of inorganic CPM (CPMin). Totals of 62%, 23% and 8% CPM were emitted from coal-fired power plants, coal-fired industrial boilers and sinter plants, respectively. By filling CPM emissions in PM2.5 simulation, the normalized mean bias (NMB) of model to observation was improved from -27% to -14% in East, North and Central China. The 4 μg/m3 PM2.5 concentration was attributed to CPM emissions in this region, accounting for 10% of observations. On "polluted" days (PM2.5>75 μg/m3), industrial CPM emissions can contribute 7 μg/m3 PM2.5 in North China. Therefore, China should focus on controlling CPM from coal combustion to ensure continuous air quality improvement.

The aim of this study was to investigate the dissolution behaviour of nitride fuels in nitric acid. One problem in employing nitrides as fuels is the formation of radiotoxic 14C upon irradiation of natural nitrogen. The use of 15N-enriched fuels would avoid this drawback. Using 15N-enriched uranium nitrides or 15N-enriched nitric acid, two methods were developed to measure the influence of the dissolution parameters, nitric acid temperature and concentration, on the 15N/14N ratios of the nitrogen, nitrogen oxides and ammonium ions utilizing a coupled gas chromatograph/mass spectrometer. This work confirms that the first dissolution step is the oxidation of UN with HNO3 to form NH4+ and HNO2 and that HNO2 has a catalytic role in the dissolution to form other products. Ammonium is the only species which contains nitrogen with the same isotopic composition as the uranium nitride.