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Wang X.,Tongji University | Wang X.,Georgia Institute of Technology | Zhao J.,Tongji University | Song J.,Tongji University | And 4 more authors.
Applied Catalysis B: Environmental | Year: 2017

In recent years, harmful algal blooms (HABs) frequently occur in eutrophic lakes all over the world. It causes the accumulation of microcystin-LR (MC-LR) in water, thus giving a great threat to aquatic animals and human beings. In this paper, a facile sol-carbonization method was used to synthesize N, P co-doped TiO2/expanded graphite by carbon layer (NPT-EGC) floating photocatalysts, which are designed for in situ photocatalytic degradation of MC-LR. XRD, N2 adsorption/desorption, FESEM/EDS, TEM, FTIR, XPS, UV–vis DRS and the PL spectrum were used to investigate the physicochemical and photoelectricity properties of the NPT-EGC photocatalysts. The results showed that NPT-EGC has a worm-like structure with N, P co-doped TiO2 particles distributed on the surface. The calcination temperatures have influences on the forming of TiO2 and carbon layer, specific surface area and photocatalytic activity. Among the different NPT-EGC photocatalysts, the photocatalyst calcined at 450 °C (NPT-EGC450) exhibited the strongest photo-absorption and the lowest recombination rate of photo-generated charge carrier. As a result, NPT-EGC450 achieved the highest removal rate of MC-LR (99.4%) following 9 h of irradiation, which is mostly attributed to photocatalytic degradation. LC–MS analysis showed most MC-LR molecules have been mineralized into small molecules. After three consecutive cycles, the NPT-EGC floating photocatalyst exhibited excellent reusability and stability, which indicates the floating photocatalysis is a promising technique for MC-LR degradation in the future. © 2017 Elsevier B.V.

Zhang J.P.,Peking University | Zhu T.,Peking University | Zhang Q.H.,Peking University | Li C.C.,Peking University | And 6 more authors.
Atmospheric Chemistry and Physics | Year: 2012

This study investigated the air pollution characteristics of synoptic-scale circulation in the Beijing megacity, and provided quantitative evaluation of the impacts of circulation patterns on air quality during the 2008 Beijing Summer Olympics. Nine weather circulation types (CTs) were objectively identified over the North China region during 2000-2009, using obliquely rotated T-mode principal component analysis (PCA). The resulting CTs were examined in relation to the local meteorology, regional transport pathways, and air quality parameters, respectively. The FLEXPART-WRF model was used to calculate 48-h backward plume trajectories for each CT. Each CT was characterized with distinct local meteorology and air mass origin. CT 1 (high pressure to the west with a strong pressure gradient) was characterized by a northwestern air mass origin, with the smallest local and southeasterly air mass sources, and CT 6 (high pressure to the northwest) had air mass sources mostly from the north and east. On the contrary, CTs 5, 8, and 9 (weak pressure field, high pressure to the east, and low pressure to the northwest, respectively) were characterized by southern and southeastern trajectories, which indicated a greater influence of high pollutant emission sources. In turn, poor air quality in Beijing (high loadings of PM 10, BC, SO 2, NO 2, NO x, O 3, AOD, and low visibility) was associated with these CTs. Good air quality in Beijing was associated with CTs 1 and 6. The average visibilities (with ±1α) in Beijing for CTs 1 and 6 during 2000-2009 were 18.5 ± 8.3 km and 14.3 ± 8.5 km, respectively. In contrast, low visibility values of 6.0 ± 3.5 km, 6.6 ± 3.7 km, and 6.7 ± 3.6 km were found in CTs 5, 8, and 9, respectively. The mean concentrations of PM10 for CTs 1, 6, 5, 8, and 9 during 2005-2009 were 90.3 ± 76.3 μg m -3, 111.7 ± 89.6 μg m -3, 173.4 ± 105.8 μg m -3, 158.4 ± 90.0 μg m -3, and 151.2 ± 93.1 μg m -3, respectively.

Analysis of the relationship between circulation pattern and air quality during the emission control period suggests that CTs are the primary drivers of day-to-day variations in pollutant concentrations over Beijing and its vicinity. During the Olympics period, the frequency of CT 6 was twice that of the mean in August from 2000 to 2009. This CT had northerly transport pathways and favorable meteorological conditions (e.g. frequent precipitation) for clean air during the Olympics. Assuming that relationships between CTs and air quality parameters in the same season are fixed in different years, the relative contributions of synoptic circulation to decreases in PM10, BC, SO2, NO2, NOx, CO, and horizontal light extinction during the Olympics were estimated as 19 ± 14%, 18 ± 13%, 41 ± 36%, 12 ± 7%, 10 ± 5%, 19 ± 11%, and 54 ± 25%, respectively. © 2012 Author(s).

Che X.,Shenzhen Academy of Environmental Science | English A.,Victoria University | Lu J.,Shenzhen Urban Planning and Research Center | Chen Y.D.,Chinese University of Hong Kong
Environmental Impact Assessment Review | Year: 2011

The enactment and implementation of the 2003 EIA Law in China institutionalised the role of plan environmental impact assessment (PEIA). While the philosophy, methodology and mechanisms of PEIA have gradually permeated through the various levels of government with a positive effect on the process and outcome of urban planning, only a few cities in China have so far carried out PEIA as a Strategic Environmental Assessment (SEA)-type procedure. One such case is the southern city of Shenzhen. During the past three decades, Shenzhen has grown from a small town to a large and booming city as China has successfully and rapidly developed its economy by adopting the "reform and open door" policy. In response to the challenges arising from the generally divergent processes of rapid urbanisation, economic transformation and environment protection, Shenzhen has incrementally adopted the SEA concept in developing the city's Master Urban Plan. As such, this paper reviews the effectiveness of PEIA in three ways: •as a tool and process for achieving more sustainable and strategic planning;•to determine the level of integration of SEA within the planning system; and,•its effectiveness vis-à-vis implementation.The implementation of PEIA within Shenzhen's Master Urban Plan offers important insights into the emergence of innovative practices in undertaking PEIA as well as theoretical contributions to the field, especially in exploring the relationship between PEIA and SEA and highlighting the central role of local governing institutions in SEA development. © 2010 Elsevier Inc.

PubMed | Beijing Normal University, Shenzhen Academy of Environmental science, Hunan University of Technology and Kunming University of Science and Technology
Type: | Journal: The Science of the total environment | Year: 2016

Understanding the relationships between land use patterns and water quality in low-order streams is useful for effective landscape planning to protect downstream water quality. A clear understanding of these relationships remains elusive due to the heterogeneity of land use patterns and scale effects. To better assess land use influences, we developed empirical models relating land use patterns to the water quality of low-order streams at different geomorphic regions across multi-scales in the Dongjiang River basin using multivariate statistical analyses. The land use pattern was quantified in terms of the composition, configuration and hydrological distance of land use types at the reach buffer, riparian corridor and catchment scales. Water was sampled under summer base flow at 56 low-order catchments, which were classified into two homogenous geomorphic groups. The results indicated that the water quality of low-order streams was most strongly affected by the configuration metrics of land use. Poorer water quality was associated with higher patch densities of cropland, orchards and grassland in the mountain catchments, whereas it was associated with a higher value for the largest patch index of urban land use in the plain catchments. The overall water quality variation was explained better by catchment scale than by riparian- or reach-scale land use, whereas the spatial scale over which land use influenced water quality also varied across specific water parameters and the geomorphic basis. Our study suggests that watershed management should adopt better landscape planning and multi-scale measures to improve water quality.

Ye Y.,Shenzhen Academy of Environmental Science | Ye Y.,Sun Yat Sen University | Peng S.,Sun Yat Sen University
Shengtai Xuebao/ Acta Ecologica Sinica | Year: 2011

Dew is one of the important water resources on the earth and is beneficial to the survival, growth and development of the plants based on the arid and semiarid environment. The disputed effects of dew on plants, beneficial and harmful, were reviewed in this study. The beneficial effects mainly consist of five aspects: (1) Supplying important water resource. In the arid and semiarid regions or in the dry season, dew is the main or the only water resource because of its higher frequency and sustaining time comparing with the precipitation, which keeps the organic synthesis and metabolism, accelerates the increase of biomass in plants. (2) Regulating inner water of plants. The function of dew on regulating inner water of plants includes the following several aspects based on related studies: helping plant to rapidly activate photosynthetic activity during desiccation and rehydration; supplying a moisture environment in repairing embryo DNA of seeds, maintaining seed viability under harsh desert conditions; regulating the transpiration pressure and helping the wilting plant arrive a higher steady restoration state; etc. (3) Improving water balance of soil. There is an indirect effect of dew on plant through improving water balance of soil. On one hand, dew forms on the soil surface or drops into the soil from the nearby plants, becoming an importing water resource. On the other hand, the soil evaporation decreases along with dew event appears, leading a mitigation of soil water tension to some extent. (4) Regulating growing environment of forest plants. The regulation effect appears on canopy firstly, and then into the forest. Dew deposition increases the water resource of forest, improves its water cycle. Along with the dew deposition and evaporation, the forest micro-climate changes, especially the wind speed, moisture and heat. Dew, as a medium, is concerned with the water-heat exchange process of the forest. (5) Dew was used widely in the performing process of foliage dressing, defoliant and pesticide for its characteristics including small dew amount, long time sustaining on objects, leading an accreting of long time, extending the time of sterilization. The harmful effects mainly consist of two aspects: (1) Inducing plant disease. The pathogen of fungus and bacteria releases spores and infects the host plant under a moisture condition, and induces plant disease easily, thus dew supplies opportunities for pathogen. The infection intensity differs from the differences of dew quantity and sustaining time. (2) Reducing output and quality of crops. The influence on the output and quality of crops is related to the quantity, sustaining time, acidification level of dew. The plant stomata movement was inhibited and the route of pollen diffusing was discouraged when the quantity and sustaining time of dew arrive at a higher level. Acid dew could lead to a degradation of vegetation for the decreasing of CO2 assimilation efficiency. Furthermore, the black spot disease of fruit could be induced by dew. The main problems in related researches were also pointed out in present paper. For example, the information of dew action effect on plants was absent; few documents referred to the changing environment, such as urban heat island and the polluted atmosphere etc; researches of dew on plant diversity and the use on biological control were lack. Future studies were recommended to (1) researches of the action effect and mechanisms of dew on plants; (2) researches on the interactions of dew and plants based on the interferential factors including acid dew and the urban heat island effect; (3) researches of the influence of dew on the plant diversity; (4) applied researches on controlling harmful plants using dew.

Liu W.,Chinese Research Academy of Environmental Sciences | Zhang L.,Chinese Research Academy of Environmental Sciences | Ye Y.,Shenzhen Academy of Environmental Science | Zou J.,Shenzhen Academy of Environmental Science
Advanced Materials Research | Year: 2011

The effects of terrestrial carbon cycle caused by Land use change on are obvious. Urbanization is an important reason of land use change. Based on the soil and plant data that field sampled, five remote sensing data of 1979, 1989, 1995, 2000 and 2003, the effects on ecosystem organic carbon pool from1979 to 2003 caused by land use change in Shenzhen city are analyzed. The land use changes are mainly occurred between the following 8 land types, farmland, wood land, grass land and construction land. The results show that form 1979 to 2003 carbon emissions caused by land use change in Shenzhen City totally reduced by 337.24 × 104Mg C (1Mg C = 1 × 106g C). The average annual carbon emissions arrive up to 24.09 × 104Mg C. Among them, the emissions caused by the reductions of farmland and forest area are respectively 252.26 × 104Mg C and 111.73 × 10 4Mg C. The organic carbon increment caused by garden land increase is 47.37 × 104Mg C. The results show that Urbanization process totally is a carbon sink process. The study is valuable for assessing the relations between carbon effects and land development and ecological restoration planning in the process of rapid urbanization. © (2011) Trans Tech Publications.

Zheng J.,South China University of Technology | Zheng J.,Pearl River Delta Atmospheric Environmental Research Joint Laboratory | Che W.,South China University of Technology | Che W.,Pearl River Delta Atmospheric Environmental Research Joint Laboratory | And 4 more authors.
Aerosol and Air Quality Research | Year: 2013

Characterizing spatial and temporal variations of PM pollution is critical for a thorough understanding of its formation, transport and accumulation in the atmosphere. In this study, Aerosol Optical Thickness (AOT) data retrieved from a Moderate Resolution Imaging Spectroradiometer (MODIS) were used to investigate the spatial and temporal variations of PM10 (particles with aerodynamic diameters of less than 10 μm) pollution in the Pearl River Delta (PRD) region. Seasonal linear regression models between 1-km retrieved MODIS AOT data and ground PM10 measurements were developed for the PRD region with meteorological corrections, and were subjected to a validation against observations from the regional air monitoring network in this region from 2006 to 2008, with an overall error of less than 50%. Consistent with ground observations, the estimated PM10 concentrations from the regression models appeared to be highest in winter, lower in autumn and spring, and lowest in summer. A high PM10 concentration band was detected over the inner part of the PRD region, where heavy industries and dense populations are located. The shape and concentration levels of this band exhibit significant seasonal variations, which shift with synoptic wind direction, indicating different source regions and their contributions to the PM10 pollution in the PRD region. Several discrete "hot spots" were found in the southwest of the PRD region during spring and other seasons, where no ground measurements are available. The reasons for the formation of these hot spots are unclear, and further investigations are needed. Despite the limitations of this work, the results demonstrate the effectiveness of retrieving remote sensing data for characterizing regional aerosol pollution, together with ground measurements. The combination of satellite data and ground monitoring presented in this work can help in better understanding the sources, formation mechanisms and transport process of particulate matters on a regional scale. © Taiwan Association for Aerosol Research.

Hosseini Bai S.,Griffith University | Hosseini Bai S.,University of The Sunshine Coast | Sun F.,Shenzhen Academy of Environmental science | Xu Z.,Griffith University | Blumfield T.J.,Griffith University
Journal of Soils and Sediments | Year: 2013

Purpose: Understorey Acacia spp. plays an important role in post-fire restoration because these understorey plants are tolerant to stress conditions. We investigated how the ecophysiological status of two species of understorey, Acacia leiocalyx and Acacia disparrima, varied depending on the plant growth stage after prescribed burning. Materials and methods: Plants were grouped in different size classes, namely seedlings, small and medium sizes, and physiological variables such as foliar gas exchange, water use efficiency and light dependency were measured at two experimental sites subjected to prescribed burning. Results and discussion: A. leiocalyx showed higher symbiotic N2 fixation and photosynthetic capacity compared to A. disparrima regardless of plant-size classes at both experimental sites. This could explain the greater relative growth rate of A. leiocalyx than that of A. disparrima. However, A. disparrima is more tolerant to shady conditions than A. leiocalyx. Conclusions: This finding may be an indication of how well these two species recover after fire, although A. leiocalyx may have faster regrowth, as it is fixing more N. © 2013 Springer-Verlag Berlin Heidelberg.

Cheng G.,Shenzhen Academy of Environmental science | Sun L.,Huazhong University of Science and Technology | Jiao L.,Huazhong University of Science and Technology | Peng L.-X.,Shenzhen Academy of Environmental science | And 3 more authors.
Desalination and Water Treatment | Year: 2013

The potential of residue biochar derived from copyrolysis of dewatered sewage sludge (80% of moisture content) and pine sawdust for the adsorption of methylene blue (MB) from aqueous solution was studied. The biochar was characterized by scanning electron microscope, X-ray fluorescence, and Brunauer-Emmet-Teller (BET). Adsorption experiments were carried out to investigate effects of various parameters on MB adsorption and evaluate the batch adsorption kinetics and isotherms. The results showed that the biochar had a BET surface area of 168.27 m2/g and the maximum adsorption capacity of 16.75 mg/g for MB at 35°C. The adsorption process was followed the second-order kinetic equation, suggesting that the adsorption might be a chemisorption process. The experimental adsorption isotherm data were well fitted with both Langmuir model and Freundlich model. © 2013 Balaban Desalination Publications.

PubMed | Georgia Institute of Technology, Shenzhen Academy of Environmental science and Auburn University
Type: | Journal: BioMed research international | Year: 2015

The photo-Fenton reaction is a promising method to treat organic contaminants in water. In this paper, a Fenton reagent enhanced by microwave electrodeless ultraviolet (MWEUV/Fenton) method was proposed for advanced treatment of nonbiodegradable organic substance in pesticide-containing biotreated wastewater. MWEUV lamp was found to be more effective for chemical oxygen demand (COD) removal than commercial mercury lamps in the Fenton process. The pseudo-first order kinetic model can well describe COD removal from pesticide-containing wastewater by MWEUV/Fenton, and the apparent rate constant (k) was 0.0125min(-1). The optimal conditions for MWEUV/Fenton process were determined as initial pH of 5, Fe(2+) dosage of 0.8mmol/L, and H2O2 dosage of 100mmol/L. Under the optimal conditions, the reaction exhibited high mineralization degrees of organics, where COD and dissolved organic carbon (DOC) concentration decreased from 183.2mg/L to 36.9mg/L and 43.5mg/L to 27.8mg/L, respectively. Three main pesticides in the wastewater, as Dimethoate, Triazophos, and Malathion, were completely removed by the MWEUV/Fenton process within 120min. The high degree of pesticides decomposition and mineralization was proved by the detected inorganic anions.

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