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Based on the estimation of carbon emissions (CE) from the power sector throughout China’s 30 administrative regions in the period of 2003 to 2013, this study investigated the space-time evolution characteristic and its determinants using spatial autocorrelation test and the spatial Durbin model (SDM). The main results are as follows: (1) The CE from power sector increased from 1.58 billion tons to 3.88 billion tons, with an average annual growth rate of 9.54%, while obvious imbalance existed among different regions. (2) According to spatial analysis, the global Moran’s I values of CE from the power sector are significantly positive during the sample period, meaning that the CE has an obvious clustering effect. The local spatial autocorrelation index confirms the imbalance of spatial distribution of the power sector’s CE. (3) Results of the spatial Durbin model show that the urbanization rate, per capita GDP, and fee-based environmental regulations have a spatial spillover effect. Based on the above findings, several policy suggestions are presented in this article.
Exploring building energy demands under the conditions of climate change can provide a basis for promoting building energy efficiency. The heating and cooling loads of commercial and residential buildings with different energy-saving standards from 1961-2009 in a large city in northern China were simulated and their responses to climate change and variability were analyzed. The results showed that the heating load for commercial buildings significantly decreased from 1961 to 2009 (P<0.01), whereas the cooling load weakly but not significantly increased over these 49 years (P>0.05). This may indicate that continuous rising temperatures in the future may apparently decrease heating load, but not largely increase energy load for cooling. The heating loads in all types of residential buildings showed a large and significant decrease from 1961 to 2009 (P < 0.01). However, decreasing rate gradually decreased from the first- to the third-stage energy-saving buildings, indicating decreasing sensitivity to climate change with enhancement of energy-saving standards. The variations of heating loads are dominantly controlled by the mean air temperature, which can explain up to 90% of the heating load. The climate change influence on the cooling load of a commercial building is dependent on month. Cooling load is dominantly related to air temperature in June and September, whereas it relates to the combination of humidity and temperature in July and August. These results may indicate that improvement of energy efficiency for building cooling should be considered by the combined effects of humidity and temperature rather than a single temperature.
The aim in this study was to assess relationships between men exposure to lead and semen-quality parameters in an environmental pollution site. We recruited 95 men through the pollution area and two controls. We measured semen quality using computer-aided semen quality analysis, and lead levels in seminal plasma using graphite gurnace atomic absorption spectroscopy. The results showed that the semen quality of men from the pollution area was lower than those of other control districts. The mean of seminal plasma lead value in the pollution area were higher than reference values for controls. Seminal plasma lead values displayed a significant negative correlation with norm morph sperm rates. Male reproductive health may be threatened by environmental pollution, and it may be influenced by local population diathesis.
In order to achieve the influence of different pretreatment methods on heat pump dried tilapia fillets, the effects of trehalose, ultrasound-assisted and freeze-thaw cycle assisted osmotic dehydration on the color, rehydration, texture and Ca2+-ATPase activity were investigated. Tilapia fi llets (100 mm length × 50 mm width × 5 mm height) were first osmoconcentrated in a trehalose solution combined with 4°C under atmospheric pressure for 1 h, different power of ultrasound and freeze-thawing respectively, then heat pump dried. The results showed that under the same drying method, the comprehensive score of ultrasound in 400 Watt was best, compared to freeze-thaw, the ultrasound pretreatment had a significant (p<0.05) effect on the color and Ca2+-ATPase activity, but had no significant (p>0.05) effect on the rehydration and texture. However, both of them significantly (p<0.05) affected the quality in comparison to that of osmosis at 4°C. It indicates that suitable ultrasonic pretreatment conditions improve the quality of dried products effectively and the conclusion of this research provides reference for heat pump dried similar products.
The dynamics of soil organic carbon (SOC) under different land uses can be beneficial for accurately assessing carbon sequestration to deal with global climate change. The aim of this study was to quantify the SOC content in various fractions under different land uses. Soil samples were collected from the top 0.1 m and 0.1-0.3 m of cropland, grassland, and forest in Huachi County of Gansu Province, China. Significant differences in physical fractions were found in the top 0.1-m layer, with cropland having the highest proportion of micro-aggregates (<250 μm), forest having the highest proportion of small macro-aggregates (250-2000 μm), and grassland tending to form large macro-aggregates (>2000 μm). SOC values were 6.9, 11.3, and 10.3 g kg⁻¹ in the top 0.1-m layer for cropland, grassland, and forest, respectively. The difference in δ¹³C between the light and heavy fraction in small macro-aggregates was smaller than that in both large macro-aggregates and micro-aggregates. These results indicated that small macro-aggregates conserved SOC relative to micro-aggregates and large macro-aggregates. The differences in δ¹³C between the light and heavy fraction in all aggregate size fractions of grassland were much larger than in forest, indicating that there was higher microbial decomposition in grasslands. Overall, our results suggested that the accumulation of SOC in grassland was derived from the abundant carbon input, but the protection of SOC from small macro-aggregates was important to forest soil.
Waterlogging is related to rainfall intensity as well as drainage network design. In previous studies, rainfall intensity was dominantly considered, while the design return period with the lowest total social investment of drainage networks was generally neglected. In this study, Guangkai Street in Tianjin in northern China was selected as a case study to determine the optimal design return period of drainage networks. According to the drainage networks for different design return periods, the depth of waterlogging was simulated based on the FloodArea model under the conditions of the rainfall exceeding the design return period. Furthermore, traffic losses due to waterlogging were determined by using the traffic loss model. When the sum of traffic losses and drainage network investment is smallest (i.e., the lowest total social investment), the corresponding return period is considered as the optimal design return period of drainage networks. By comparing the simulated depths of waterlogging and observations of 17 waterlogging monitoring points, we found that the FloodArea model has efficient simulation in most areas. Accordingly, the FloodArea model was used to simulate the depths of waterlogging with different return periods in Guangkai Street. The results show that the total social investment, including traffic losses and initial investment of drainage networks, is the lowest with the return period of the drainage networks in the selected area being designed as 5 years. This suggests that the design return period of the drainage networks in Guangkai Street should be upgraded to 5 years. The approach in this study is based on high-precision simulation (1 m GIS data) and actual waterlogging depth to ensure the accuracy of simulation. The optimal design return period is calculated in combination with traffic losses and initial investment of drainage networks, providing reference for the design of drainage networks in specific areas.
The hot convective drying of fresh tilapia fillets was evaluated in a heat pump dryer. The influence of the drying temperature (35, 45 and 55°C), hot air velocity (1.50, 2.50 and 3.50 m/s) and thickness (3, 5 and 7 mm) of the tilapia fillets on the moisture ratio and drying rate has been studied. It shows that drying process took place in falling rate periods. The experimental drying data of fresh tilapia fillets under different conditions was fitted to nine different commonly used thin-layer drying models by nonlinear fitting methods and all the models were compared according to three statistical parameters, i.e. coefficient of determination, the reduced chi-square and the root mean square error. It was found that the coefficient of determination values of Page were higher than 0.99254, and the corresponding reduced chi-square and the root mean square error values were lower than 0.000632219 and 0.023854, respectively, indicating that the Page model is the best to describe drying curves of fresh tilapia fillets among them. Effective moisture diffusivity ranged from 6.55×10–10 to 1.23×10–9 m2/s calculated using the Fick’s second law. With the increase of the drying temperature and the hot air velocity, the effective moisture diffusivities Deff increased. The value of drying activation energy of tilapia fillets with thickness of 3 mm at hot air velocity 2.50 m/s was 17.66 kJ/mol, as determined from the slope of the Arrhenius plot, ln(Deff) versus 1/Ta.
Nutrients may be mobilized from senescing leaves and transported to other plant tissues, enabling plants to conserve them and reuse. Nitrogen and phosphorus are two dominant nutrients related to photosynthetic capacity and limiting plant growth. In this study, we examined the effect of canopy height on nutrient use by analyzing N and P concentrations of green and senescent leaves collected from different canopy heights of Abies georgei var. smithii (Viguie et Gaussen) Cheng growing at the alpine timberline in Sergyemla Mt. (4 350 m a.s.l), southeastern Tibetan Plateau. The results showed that N and P concentrations per unit needle mass decreased significantly with needle age, but no significant difference was found among upper, middle and lower canopy. However, area-based N and P concentrations increased with the height of canopy. The leaf level nutrient resorption and use efficiency varied in the order: upper canopy> middle canopy >lower canopy for both N and P. The higher nutrient resorption efficiency had significant relationship with leaf level nutrient use efficiency, that is, higher leaf level nutrient use efficiency was partly due to the high resorption from senescent needles. Additionally, the higher nutrient resorption was related to high current nutrient concentration. Vertical variations of leaf level nutrient use efficiency in this study reflected the strategy of alpine trees to respond to imbalance between light availability and soil nutrients.
The native alpine plant Saussurea superba is widely distributed in Qinghai–Tibetan Plateau regions. The leaves of S. superba grow in whorled rosettes, and are horizontally oriented to maximize sunlight exposure. Experiments were conducted in an alpine Kobresia humilis meadow near Haibei Alpine Meadow Ecosystem Research Station (37º29'–37º45'N, 101º12'–101º33'E; alt. 3200 m). Leaf growth, photosynthetic pigments and chlorophyll fluorescence parameters were measured in expanding leaves of S. superba. The results indicate that leaf area increased progressively from inner younger leaves to outside fully expanded ones, and then slightly decreased in nearly senescent leaves, due to early unfavorable environmental conditions, deviating from the ordinary growth pattern. The specific leaf area decreased before leaves were fully expanded, and the leaf thickness was largest in mature leaves. There were no significant changes in the content of chlorophylls (Chl) and carotenoids (Car), but the ratios of Chl a/b and Car/Chl declined after full expansion of the leaves. The variation of Chl a/b coincided well with changes in photochemical quenching (qP) and the fraction of open PSII reaction centers (qL). The maximum quantum efficiency of PSII photochemistry after 5 min dark relaxation (F(v)/F(m)) continuously increased from younger leaves to fully mature leaves, suggesting that mature leaves could recover more quickly from photoinhibition than younger leaves. The light-harvesting capacity was relatively steady during leaf expansion, as indicated by the maximum quantum efficiency of open PSII centers (F'v/F'm). UV-absorbing compounds could effectively screen harmful solar radiation, and are a main protection way on the photosynthetic apparatus. The decline of qP and qL during maturation, together with limitation of quantum efficiency of PSII reaction centers (L(PFD)), shows a decrease of oxidation state of QA in PSII reaction centers under natural sunlight. Furthermore, light-induced (ΦNPQ) and non-light-induced quenching (ΦNO) were consistent with variation of L(PFD). It is concluded that the leaves of S. superba could be classified into four functional groups: young, fully expanded, mature, and senescent. Quick recovery from photoinhibition was correlated with protection by screening pigments, and high level of light energy trapping was correlated with preservation of photosynthetic pigments. Increasing of ΦNPQ and ΦNO during leaves maturation indicates that both thermal dissipation of excessive excitation energy in safety and potential threat to photosynthetic apparatus were strengthened due to the declination of qP and qL, and enhancement of L(PFD).
Distribution of 18S-26S rDNA on the chromosomes of Dendranthema nankingense and its two close-related species D. nankingense and D. lavendulifolium was studied by fluorescent in situ hybridization with a JHD 2-15A DNA clone: Six rDNA loci were found in D. nankingense, eight in D. lavendulifolium, and twelve in D. indicum. The rDNA loci number and pattern were applied to analyze the phylogenetic relationship of the three closely related species.
In recent years, biochar, a new environmentally functional material, has received widespread attention as a soil amendment for its special structures and characteristics, such as improving soil texture and increasing crop yield. However, controversies still exist for the effects of biochar addition to soil nitrogen(N) cycles. This study focuses on the influences of 350ºC peanut biochar application on N mineralization in abandoned orchard soil during a 46-day incubation. The treatments contained control (CK), 1% biochar (BC), and 3% biochar (BC). Results showed that 350ºC peanut biochar increased soil pH and EC, but decreased soil urease activities significantly. Biochar decreased soil net-mineralized N significantly, and a higher biochar addition content resulted in lower soil mineralized N concentration. NO3–-N content accounted for more than 94% of soil inorganic N for all three treatments during the entire incubation time, while the presence of biochar did not change this characteristic. Conclusions indicated that the addition of 350ºC peanut biochar significantly inhibited orchard soil N mineralization in a short time by altering soil physical and chemical properties.
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