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Highlights: [•] Contents of 47 POPs in 17 vegetables in Huizhou were examined. [•] Daily intakes of 47 pollutants by consumption of vegetables were estimated. [•] Organochlorine pesticides were the major contributors to residents’ health risks. [•] Health risks from leafy vegetables exceeded those for gourd and fruit vegetables. [•] Health risks from single pollutants were low but from total pollutants were high. [ABSTRACT FROM AUTHOR] more...

It has been found thatSauropusandrogynushas a strong adaptive capacity in multiple heavy-metal-contaminated soils. Field trials in highly heavy-metal-contaminated soils were conducted to investigate the extraction efficiency of Cd, Cu, Pb, and Zn byS. androgynus. The yield ofS. androgynuscould reach 10.01 t ha−1, and the amount of Cd, Cu, Pb, and Zn extracted by the plant was 57.36, 218.57, 2078.11, and 19.64 g ha−1, respectively.S. androgynusremoved 0.35%, 0.01%, 0.03%, and 1.37% of the total soil Cd, Cu, Pb, and Zn in one growing season, respectively. By comparing the extracting capability and yield with some hyperaccumulators reported in the literature,S. androgynuswas considered to be a highly effective plant to extract heavy metals (Cd, Cu, Pb, and Zn). The plant should be useful for phytoextraction of soils contaminated by the heavy metals. [ABSTRACT FROM PUBLISHER] more...

Abstract: Vegetative riparian buffers are considered as key zones in providing natural regulation functions for water quality aimed at intercepting non-point source (NPS) nutrients from upslope areas to surface water. The function for reducing NPS nutrients may perform better in some locations than in others because not all factors affecting nutrient mitigation are equal in all locations. This paper intended to develop a spatial multi-criteria planning scheme involving nutrient export and buffer characteristics to evaluate the buffer restoration priorities. The Liuxihe River basin, located in central Guangdong Province, was used as a case study area for this research. Six indicators, including total nitrogen export, total phosphorous export, mean buffer width, buffer gap ratio, vegetation vigor and soil erodibility, were all integrated to assess priority. The Soil and Water Assessment Tool (SWAT) model was applied to simulate total nitrogen export and total phosphorous export traveling from upslope areas to the buffer. Other indicators representing the buffer mitigation potential of NPS nutrients were calculated with the help of the Geographic Information System (GIS). To reduce redundancy and objectively discriminate the importance among indicators, a principle component weighting method was used to ascribe weights to each indicator. Total nitrogen export and total phosphorous export, which quantified the NPS nutrients export, were assigned the highest weights of 3.30 and 3.16, respectively. The aggregation result of the multi-criteria analysis generated a distribution map ranking the buffer restoration priorities. The results suggested that restoring the riparian buffers in sub-basins located in the lower reaches of Liuxihe River basin should be a priority. This planning strategy can be applied as a useful supporting tool for water quality management on watershed scale. [Copyright &y& Elsevier] more...

Abstract: Soil heavy metal contamination is a major environmental concern, and the ecological risk associated with heavy metals is increasing. In this paper, we investigated heavy metal contamination near Dabaoshan Mine by: using sequential indicator simulation to delineate the spatial patterns of soil data; fitting multiple linear regression models for heavy metal uptake by crops; interpreting land uses from remote sensing images and integrating the spatial patterns, uptake models and land uses into a dose–response model for human health risks from heavy metals. The areas with elevated soil heavy metal concentrations are mainly located at the Dabaoshan Mine site and in the watershed basins of the Hengshi, Tielong and Chuandu rivers. The average concentrations of Cu, Zn, Cd and Pb in soil in the study area are all above the natural soil background levels, but Cd is the major contributor to human health risk in the area. Areas of low soil pH are also found throughout the watershed basins of the Hengshi, Tielong and Chuandu rivers. Of the different land use types in the study area, agricultural and residential land uses have the highest human health risk because ingestion is the dominant exposure pathway for heavy metals. The spatial patterns of the heavy metal concentrations and soil pH indicate that the areas with the highest human health risk regions do not directly coincide with the areas of highest heavy metal concentrations, but do coincide with the areas of lower soil pH. The contamination with high concentrations of heavy metals provides the risk source, but the combination of high heavy metal concentrations, low pH and agricultural or residential land use is required for human health risks to be present. The spatial pattern of the hazard quotients indicates that Cd is the most important pollutant contributing to the human health risk. [Copyright &y& Elsevier] more...

Abstract: It is crucial to separate the soil geochemical background concentrations from anthropogenic anomalies and to provide a realistic environmental geochemical map honoring the fluctuations in original data. This study was carried out in the Hengshi River watershed, north of Guangdong, China and the method proposed combined exploratory data analysis (EDA), sequential indicator co-simulation (SIcS) and the ratio of isothermal remnant magnetization (S 100 =−IRM−100mT/SIRM). The results showed that this is robust procedure for defining and mapping soil geochemical background concentrations in mineralized regions. The rock magnetic parameter helps to improve the mapping process by distinguishing anthropogenic influences. In this study, the geochemical backgrounds for four potentially toxic heavy metals (copper 200mg/kg; zinc 230mg/kg; lead 190mg/kg and cadmium 1.85mg/kg) Cu, Zn and Cd exceeded the soil Grade II limits (for pH<6.5) from the Chinese Environmental Quality Standard for Soils (GB 15618-1995) (EQSS) which are 100, 200, 250 and 0.3mg/kg for Cu, Zn, Pb and Cd, respectively. In particular, the geochemical background level for Cd exceeds standard six times. Results suggest that local public health is at high-risk along the riparian region of the Hengshi River, although the watershed ecosystem has not been severely disturbed. [Copyright &y& Elsevier] more...

The extent of microbial community diversity in two similar sandy surface soils from Virginia and Delaware (USA) was analysed with a culture-independent small subunit ribosomal RNA (SSU rRNA) gene-based cloning approach with about 400–700 SSU rDNA clones obtained from each sample. While there were no operational taxonomic units (OTUs) having more than three individuals, about 96–99% of the OTUs had only a single individual. The clones showing less than 85% similarity to the sequences in the current databases were fully sequenced. The majority of the clones (55%) had sequences that were more than 20% different from those in the current databases. About 37% of the clones differed by 15–20% in sequence from the database, 16% of the clones differed by 10–15%, and 5% of the clones differed by only 1–10%. Phylogenetic analysis indicated that these sequences fell into 10 of the 35–40 known phylogenetic divisions. Many of the clones were affiliated with Acidobacterium (35%). While a substantial portion of the clones belong to alpha (24%) and beta (12%) Proteobacteria, a few of them were affiliated with delta (6%) and gamma (3%) Proteobacteria. About 6% of the clones belong to Planctomycetes, and 4% of the clones were related to gram-positive bacteria. About 4% of clones were related to other bacterial divisions, including Cytophaga, Green sulfur bacteria, Nitrospira, OP10, and Verrucomicrobia. Eight sequences had no specific association with any of the known divisions or candidate divisions and were phylogenetically divided into three novel division level groups, named AD1, AD2 and AD3. Candidate division AD1 represented by six clones (4%) was found in both sites and consisted of two subdivisions. The community structures were similar between these two widely separated, sandy, oligotrophic, surface soils under grass vegetation in a temperate, humid climate but somewhat dissimilar to community structures revealed in similar studies in other types of soil habitats. [Copyright &y& Elsevier] more...

Examines the structure of soil microbial communities. Extraction of DNA from different soil samples; Use of amplification ribosomal DNA restriction analysis; Application of the spatial isolation hypothesis. more...

There is a significant challenge in resource management: the perceived trade-off between economic growth and ecosystem conservation. In this study, we integrate a variety of quantitative research methods and models, such as the ecosystem service value (ESV), interval parameter planning (IPP), Dyna-CLUE, and Monte Carlo methods, in an attempt to balance the ESV and economic benefits. The highest system benefits can be obtained, and uncertainty in the ecosystem assessment is considered. Taking the Pearl River Delta as the study area, the results show that when the GDP growth rate is less than 6%, the ESV in 2025 will be higher than the ESV in 2017. An interval approach (upper and lower bounds) is used. For a scenario with a 5% GDP growth rate, the ESV is RMB¥ [1.85, 20.79] × 109, which is more than the ESV of the scenario with a 9% GDP growth rate. When the GDP growth rates are 5% and 9%, the proportions of forestland are [61.5%, 61.7%] and [58%, 58.2%], respectively. Furthermore, spatialization was performed using the Dyna-CLUE model. In 2025, the simulated area of farmland is larger in some small regions with 9% GDP growth rate than it is in regions with 5% GDP growth rate, thus achieving a balance between occupation and compensation of regional farmland. By comparing ecosystem planning under different GDP growth rates, an optimized land-use allocation method can help decision makers balance system benefits and ecological risks, which can provide multiple options and specific locations for decision. Image 1 • A model was built to balance ecosystem services (ES) and economic benefits. • An evaluation system was built to assess the ESV in the lower and upper bounds. • Spatial differences in both ESV and land-use efficiency are considered. • An interval parameter planning (IPP) method and Dyna-CLUE model are integrated. • Decision makers are supported to balance system benefits and ecological risks. [ABSTRACT FROM AUTHOR] more...

Heavy metal contamination of agricultural lands may give rise to health risks by cultivation and consumption of food crops from such lands, as well as result in economic loss. Phytoremediation is an eco-friendly and cost-effective approach to restore contaminated soil. However, the restoration process is slow and its sustainability is difficult to maintain. Bioenergy crops may provide alternative economic benefits to agriculture sector and reduce the risks associated with transfering heavy metals into food webs. In this study, a field experiment was carried out to determine the level of reclamation that would be attained in severely heavy metal-contaminated land by planting cassava (Manihot esculenta), a bioenergy crop. The results showed that cassava could grow well on the derelict land, with a fresh tuber yield of 23.13–26.22 t ha−1 in one growing season, which could potentially produce 3680–4160 L ha−1 bioethanol. The economic income of the cassava was estimated to be 11.6–13.1 × 103 CNY ha−1. Among the cassava tissues, metal concentrations were lowest in the tuber. The soil fertility and acidity were ameliorated after cassava plantation, and the mobile and bioavailable metal fractions in the soils were decreased. The cultivation of cassava as a renewable energy crop appears applicable for sustainable utilization and reclamation of heavy metal-contaminated land. [ABSTRACT FROM AUTHOR] more...

• ESDA was applied to estimate the pattern of ecological security (ES) in PRD, China. • Hot and cold spots for the spatial distribution of ES were identified. • Optimal management was proposed from three categories for each municipality. • The main factors influencing ES distribution were explored using semivariance. The ecological security (ES) pattern in China is gaining considerable attention worldwide due to intensifying urban development and human activities that threaten ecosystem structures and ecological processes. The Pearl River Delta (PRD) has experienced intense economic development for nearly 40 years; however, the ES pattern in the PRD is poorly understood. In this paper, we used a multisource data approach to assess ES, performed downscaling to a 1 × 1 km2 grid size, and applied spatial statistics to analyze the ES pattern in the PRD. We found three natural "ecological buffers," namely, nature reserves and forest patches covering several municipalities in the delta, thus guaranteeing the socio-economic development of this highly urbanized area. The spatial autocorrelation results indicated that the ES pattern is significantly spatially correlative (p = 0.001), with a Moran's I of 0.7766. We identified several hot and cold spots for the ES spatial distribution that occupied 58.49% of the PRD's total area. Moreover, a semivariance analysis showed that structural factors are dominant in the ES spatial distribution. Based on the ES area proportions, the 9 municipalities of the PRD can be grouped into three categories: optimized development zones, comprehensive development zones, and ecological conservation development areas. Zhaoqing, Huizhou and Jiangmen are key areas for improving ES conservation in the PRD. In this study, we explore an ES assessment model coupled with a spatial heterogeneity analysis to provide insights into ecological conservation efforts in urban agglomerations. [ABSTRACT FROM AUTHOR] more...

Urban green infrastructures (GIs) are proved to effectively mitigate urban warming associated with urbanization, and beneficial to the thermal comfort and energy consumption. Quantifying the impacts of urbanization on microclimate and delineating possible urban GIs strategies to maximize their thermal benefits and energy saving potential are thus of importance. This study examined the impacts of the urban growth in Kwai Chung (a fast-developing urban area in Shenzhen, China) on the local microclimate and thermal comfort by conducting the field measurements inside and outside this area. The contribution of urban warming to the daytime mean Ta was up to 4.9 °C in the warm period, which profoundly exacerbated the heat stress. Using a validated ENVI-met model, numerical simulations were conducted to evaluate the thermal benefits and energy saving potentials of the current trees (mainly located in an urban park) and three designed urban GIs (greenway, green roof and grove) in a high-density residential neighborhood. The results revealed that urban park is capable of regulating the hot and cold environment in adjacent urban zones, resulting in improvements of thermal comfort and 3D energy savings of 24.7 and 40.0 kW per day, respectively in the warm and cool periods. Among the designed urban GIs, greenway manifested the best performance on microclimate regulation and energy saving. This research helps the decision-makers and urban planners to delineate the possible urban GIs strategies to optimize the environmental benefit for achieving 'smart' urban growth. • Thermal impacts of urbanization in a fast-developing city was determined. • Thermal benefit and energy saving of 3 designed green infrastructure were evaluated. • Urbanization exacerbated urban heat stress with increment of 4.9 °C daytime mean Ta. • Urban park potentially saved energy of 24.7 kW in summer and 40.0 kW in winter. • Greenway performed best in microclimate regulation and energy saving. [ABSTRACT FROM AUTHOR] more...

Blue-green infrastructures, including reservoirs, lakes, forests and green spaces, play important roles in the microclimate environment. This study investigated the effects of blue-green infrastructures on the surface temperature adjacent to 12 reservoirs in the Pearl River Delta area, China. The temperature of each reservoir and its surrounding environment was retrieved by Landsat Thematic Mapper (TM) remote sensing imagery. The relationship between the temperature fields around the reservoir and the influencing factors was analyzed with statistical analysis. The results showed that distance (D), underlying surface type, and reservoir capacity (V) had significant effects on the temperature fields around the reservoirs. The temperatures across distances of 0–100 m and 0–200 m away from the reservoir boundary had a linear relationship with distance. The effect of the reservoir on temperature gradually declined when the distance exceeded 200 m. In the 0–300 m range, a quadratic equation with an intercept best fitted the relationship between temperature and distance. Four types of underlying surfaces, including built-up land, bare land, sparse forest land and forest land, were quantified by the normalized difference vegetation index (NDVI). Subsequently, a quadratic model expressing the correlation between temperature and the NDVI was obtained. Moreover, the surface temperature at the reservoir edge was negatively correlated to V. Finally, a multiple nonlinear regression equation was found to effectively describe the influence of D, NDVI and V on temperature fields around reservoirs. The influence of reservoir and vegetation (i.e., NDVI) on the field and their contributions were calculated by mathematical methods. The effects of the reservoir and vegetation on the peripheral temperature interacted with each other; the influence of the reservoir and the vegetation on temperature declined and increased, respectively, as distance increased. By addressing the influence of reservoirs and forests on temperature fields and cooling contribution rates, this study provides more insight into the role of blue-green infrastructure in the urban thermal environment. [ABSTRACT FROM AUTHOR] more...

Dissolved organic matter (DOM) was leached from leaves of two trees commonly grown in subtropical regions, Pinus elliottii (commonly known as slash pine) and Schima superba (S. superba) , and its degradation pattern and potential for forming disinfection byproducts (DBPs) were evaluated. The leaves were exposed in the field for up to one year before leaching. The DOM leached from slash pine litter contained on average 10.4 mg of dissolved organic carbon (DOC) per gram of dry weight; for S. superba the average was 37.2 mg-DOC/g-dry weight. Ultraviolet and visible light absorbance, fluorescence, and molecular weight analysis indicated that more aromatic/humic and higher molecular weight compounds are formed as leaf litter ages. A 4-component parallel factor analysis of the fluorescence data showed that the intensity of peaks related with protein-like components decreased gradually during biodegradation, while that of peaks attributed to humic-acid-like components increased continuously. Fresh slash pine leachates formed on average 40.0 μg of trihalomethane (THM) per milligram of DOC, while S. superba leachates formed 45.6 μg. THM formation showed peak values of 55.7 μg/mg DOC for slash pine and 74.9 μg/mg DOC for S. superba after 8 months of aging. The formation of haloacetonitrile (HAN) and trichloronitromethane (TCNM) increased with increasing leaf age, while chloral hydrate (CH) formation did not show such a trend. Specific UV absorbance showed some positive correlation with DBPs, but humic-acid-like and protein-like absorbance peaks correlated with CH and TCNM yields in only some leaf samples. [ABSTRACT FROM AUTHOR] more...

With rapid economic development and increasing population, the urbanization process is accelerated, and serious air pollution threatens human health. Urban green infrastructure (UGI) planning has proven effective in improving air quality. However, how to improve air quality through UGI planning in different urban forms remains unclear. Therefore, based on the local climate zone (LCZ) of Guangzhou, this study used the i-Tree Eco model to evaluate the removal efficiency of air pollutants under different UGI designs. The results showed that from 2013 to 2019, the Built Type LCZ gradually replaced the Land Cover Type in Guangzhou, indicating the rapid urbanization process. The air pollution of the Built Type LCZs was more serious than that of the Land Cover Type. Roadside green space was more effective for air quality improvement when applied on a larger scale with the more addable area, while applying city park green space was an alternative at a local scale with limited area. The optimal designs of UGI varied within different LCZs. Adding street trees and shrubs by 20% in the urban expansion area was the optimal design for LCZ 6. For LCZ 4, adding 20% of city park trees in the urban expansion area and 5% of overall shrubs were optimal. This study proposed a practical approach for colligating the LCZ concept and i-Tree Eco simulation for air quality improvement. [ABSTRACT FROM AUTHOR] more...

The Pearl River Delta region has experienced rapid urbanization and economic development during the past 20 years. To investigate the impacts of urbanization on regional climate, the Advanced Research core of the Weather Research and Forecasting (ARW-WRF) model is used to conduct a pair of 1-yr simulations with two different representations of urbanization. Results show that the reduction in vegetated and irrigated cropland due to urban expansion significantly modifies the near-surface temperature, humidity, wind speed, and regional precipitation, which are obtained based on the significance t test of the differences between two simulations with different urbanization representations at the 95% level. Urbanization causes the mean 2-m temperature over urbanized areas to increase in all seasons (from spring to winter: 1.7° ± 0.7°C, 1.4° ± 0.3°C, 1.3° ± 0.3°, and 0.9° ± 0.4°C, respectively) and the urban diurnal temperature range decreases in three seasons and increases in one (from spring to winter: −0.5° ± 0.3°C, +0.6° ± 0.3°C, −0.4° ± 0.2°C, and −0.8° ± 0.2°C, respectively). Urbanization reduces near-surface water vapor (1.5 g kg−1 in summer and 0.4 g kg−1 in winter), 10-m wind speed (37% independent of season), and annual total precipitation days (approximately 6-14 days). However, the total rainfall amount increases by approximately 30%, since the decrease in the number of days with light rain (8-12) is overcome by the increase in the number of days of heavy or extreme rain (3-6), suggesting that urbanization induces more heavy rain events over the urban areas. Overall, the effect of urbanization on regional climate in the Pearl River Delta is found to be significant and must be considered in any broader regional climate assessment. [ABSTRACT FROM AUTHOR] more...

Abstract: Hourly measurements of O3, NO, NO2, PAN, HNO3 and NO y concentrations, and eddy-covariance fluxes of O3 and NO y over a temperate deciduous forest from June to November, 2000 were used to evaluate the dry deposition velocities (V d) estimated by the WRF-Chem dry deposition module (WDDM), which adopted scheme for surface resistance (R c), and the Noah land surface model coupled with a photosynthesis-based Gas-exchange Evapotranspiration Model (Noah-GEM). Noah-GEM produced better V d(O3) variations due to its more realistically simulated stomatal resistance (R s) than WDDM. V d(O3) is very sensitive to the minimum canopy stomatal resistance (R i) which is specified for each seasonal category assigned in WDDM. Treating Sep-Oct as autumn in WDDM for this deciduous forest site caused a large underprediction of V d(O3) due to the leafless assumption in ‘autumn’ seasonal category for which an infinite R i was assigned. Reducing R i to a value of 70sm−1, the same as the default value for the summer season category, the modeled and measured V d(O3) agreed reasonably well. HNO3 was found to dominate the NO y flux during the measurement period; thus the modeled V d(NO y ) was mainly controlled by the aerodynamic and quasi-laminar sublayer resistances (R a and R b), both being sensitive to the surface roughness length (z 0). Using an appropriate value for z 0 (10% of canopy height), WDDM and Noah-GEM agreed well with the observed daytime V d(NO y ). The differences in V d(HNO3) between WDDM and Noah-GEM were small due to the small differences in the calculated R a and R b between the two models; however, the differences in R c of NO2 and PAN between the two models reached a factor of 1.1–1.5, which in turn caused a factor of 1.1–1.3 differences for V d. Combining the measured concentrations and modeled V d, NO x , PAN and HNO3 accounted for 19%, 4%, and 70% of the measured NO y fluxes, respectively. [Copyright &y& Elsevier] more...

This study intended to provide 4-km gridded, hourly, year-long, regional estimates of terpenoid emissions in the Pearl River Delta (PRD), China. It combined Thematic Mapper images and local-survey data to characterize plant functional types, and used observed emission potential of biogenic volatile organic compounds (BVOC) from local plant species and high-resolution meteorological outputs from the MM5 model to constrain the MEGAN BVOC-emission model. The estimated annual emissions for isoprene, monoterpene and sesquiterpene are 95.55 × 10 kg C, 117.35 × 10 kg C and 9.77 × 10 kg C, respectively. The results show strong variabilities of terpenoid emissions spanning diurnal and seasonal time scales, which are mainly distributed in the remote areas (with more vegetation and less economic development) in PRD. Using MODIS PFTs data reduced terpenoid emissions by 27% in remote areas. Using MEGAN-model default emission factors led to a 24% increase in BVOC emission. The model errors of temperature and radiation in MM5 output were used to assess impacts of uncertainties in meteorological forcing on emissions: increasing (decreasing) temperature and downward shortwave radiation produces more (less) terpenoid emissions for July and January. Strong temporal variability of terpenoid emissions leads to enhanced ozone formation during midday in rural areas where the anthropogenic VOC emissions are limited. [ABSTRACT FROM AUTHOR] more...

• Effects of water matrices on 36 micropollutants degradation by UV/NH 2 Cl were investigated. • Linear function was found between RCS and RNS activity and Hammett Σσ+ constant. • Cl− enhanced Cl 2 •– formation, leading to increased removal of some micropollutants. • Br− inhibited micropollutant degradation due to lower reactivity of RBS than RCS. • I− produced HOI and RIS, facilitating the degradation of phenols and sulfonamides. The UV/monochloramine (UV/NH 2 Cl) process has attracted increasing attention in water treatment, in which hydroxyl radicals (HO•), reactive chlorine species (RCS) and reactive nitrogen species (RNS) are produced. This study investigated the effects of water matrices including halides, natural organic matter (NOM), alkalinity and pH, on the degradation kinetic of a variety of micropollutants and radical chemistry in the UV/NH 2 Cl process. The presence of chloride blunted HO• and Cl• impacts, but enhanced Cl 2 •– effect on micropollutants reactive toward Cl 2 •–. The presence of 30 μM bromide led to an 82% decrease in the specific pseudo-first-order rate constants (k ′) by HO• (k HO• ′), and significantly diminished RCS efficacy. Reactive bromine species (RBS) were formed in the presence of bromide, while the contribution could not compensate for the decrease of HO• and RCS due to their lower reactivity toward micropollutants. Iodide rapidly transformed to HOI via reacting with NH 2 Cl, which resulted in a 59% decrease of k HO• ′ and 12% ∼ 100% decreases of k ′ by reactive halogen species (RHS) and RNS (k RHS + RNS ′) for most micropollutants. Nevertheless, k ′ of phenolic compounds, such as paracetamol, bisphenol A and salbutamol, increased in the presence of iodide by 78%, 360% and 130%, respectively, due to the roles of HOI and reactive iodine species (RIS). Bicarbonate decreased the contributions of HO• and RCS, but enhanced that of CO 3 •− for micropollutants reactive toward CO 3 •−. The presence of 1 mg/L NOM scavenged over half the amount of HO•, and also consumed RCS and RNS, resulting in significantly decreased removal of micropollutants. High pH value witnessed enhanced degradation for those micropollutants reactive toward RCS and RNS through deprotonation. The degradation of most micropollutants was inhibited in real drinking water and in the coexistence of halides. This study provides a better understanding of radical chemistry in the UV/NH 2 Cl process under a practical water treatment condition. [Display omitted] [ABSTRACT FROM AUTHOR] more...

Analyzing the distribution of air pollution and its influencing factors is critical for regional air pollution prevention and control. This study takes the Pearl River Delta (PRD) as a study area, analyzes the spatial-temporal changes in air pollution (including sulfur dioxide (SO 2), nitrogen dioxide (NO 2), ozone (O 3), carbon monoxide (CO), and particles with an aerodynamic diameter less than 10 μm (PM 10) and less than 2.5 μm (PM 2.5)) from 2006 to 2019, and explores the relationship between air pollution and meteorological factors. The results showed that (1) most air pollutant concentrations decreased from 2006 to 2019, with the most obvious change being the decrease in the SO 2 concentration from 52.4 μg/m3 to 7.8 μg/m3. The O 3 concentration increased, with a Sen's slope of 0.649 μg m−3·year−1. Air pollution was lower in coastal areas (Shenzhen and Huizhou) than in inland areas (Foshan and Zhaoqing), affected by ocean atmospheric transmission, and coastal areas had the cleanest air quality. (2) Air pollutants had high correlations with air pressure, relative humidity, precipitation, and temperature. The most serious air pollution was found in winter, which was partially due to the meteorological conditions in winter that were more unfavorable for pollutant dispersion and dilution than were the conditions in other seasons. (3) Through the wavelet coherence method, an interesting finding revealed that other air pollution and meteorological factors exhibited complex period-dependent characteristics that were significantly related to PM 2.5. Areas with less air pollution were more susceptible to meteorological factors. (4) The overlapping area of the PM 2.5 distribution hotspot and nighttime light hotspot was mainly in Foshan and Guangzhou, representing approximately 12.1% of the study area. Our work contributes to the literature by considering seasonal and timescale-dependent characteristics of meteorological factors affecting air pollutant emissions, and it provides new insights into recognizing regions that need to prioritize urban air pollution control based on hotspot analysis. [Display omitted] • The mean SO 2 concentration decreased from 52.4 μg/m3 in 2006 to 7.8 μg/m3 in 2019. • The O 3 concentration increased with a Sen's slope of 0.649 μg m−3·year−1. • The time-frequency relationship between PM 2.5 and meteorological factors was explored by wavelet coherence. • Higher air pollution was detected in regions with higher night-time brightness. [ABSTRACT FROM AUTHOR] more...

[Display omitted] • Ecological sources were identified using morphological spatial pattern analysis. • Resistance surface was developed from ecosystem service value. • Ecological corridors were identified using minimum cumulative resistance model. • The ecological network was optimized by similarity search. Ecological infrastructure is a popular framework for conservation planning. In this paper, one of the most urbanized regions of China-Shenzhen was chosen as the study area. Ecological infrastructure with different configurations and functions were identified and combined to form the urban ecological network. The ecological sources were identified using morphological spatial pattern analysis (MSPA) and landscape connectivity analysis. The ecological resistance surface developed from ecosystem service value was modified basing on ecological sensitivity and landscape connectivity. The ecological network was constructed by minimum cumulative resistance (MCR) model and then optimized and accessed. The results show that: (1) the ecological network consists of 25 ecological sources distributed mainly in the southeast and west. Twenty-nine ecological corridors were extracted and 36 ecological nodes identified. (2) In the optimized ecological network, 10 new ecological sources were added, and 46 ecological corridors and 59 ecological nodes were identified. It would promote the connectivity of the ecological sources and the stability of ecological functioning process. (3) The ecological network took ecosystem service value and ecological sensitivity into consideration and lays emphasis on improving landscape connectivity, providing an approach to optimizing urban ecological network and contributing to urban planning. [ABSTRACT FROM AUTHOR] more...

Energy consumption, water use and carbon emission targets are important for promoting sustainable development. This study presents a multi-goal analytical framework based on an environmental input-output analysis, structural path analysis and correspondence analysis to identify the key sectors for energy, water and carbon footprints. Using Guangdong Province as a case study, the energy, water and carbon footprints are modelled from production-based, consumption-based and network (betweenness)-based perspectives. The results show that (1) the construction sector is a key sector for energy use/water use/carbon emissions from the three perspectives. The electricity and heat power production and supply sector emitted the most production-based CO 2 (283.4 Mt), accounting for 52.3% of the total CO 2 emissions. (2) The key sectors in terms of energy, water and carbon differ. The transport, storage and post sector is an important sector for energy consumption, and the agriculture sector and food and tobacco sector are important sectors for freshwater withdrawal. (3) The key sectors differ according to the three perspectives. For example, the energy production sector ranked first in production-based CO 2 emissions (286.2 Mt), but heavy manufacturing ranked first in consumption-based CO 2 emissions (146.3 Mt). This study recommends paying more attention to the abovementioned sectors, specifically concerning the transmission role of light manufacturing in freshwater withdrawal, and reducing energy consumption-intensive but low value-added exports (such as metal smelting and pressing). The findings highlight the need to consider multiple angles and elements to identify the key sectors and help decision makers better understand the relationships and flows among the industries. Unlabelled Image • Key sectors identified from production-, consumption- and network-based views. • Flows of energy consumption, freshwater withdrawal and CO 2 emissions are mapped. • The CO 2 transfer path from the energy sector to heavy manufacturing is highlighted. • Export-oriented products with high resource use but low value-added must decrease. [ABSTRACT FROM AUTHOR] more...

With the rapid economic development and tremendous urban expansion, cities frequently experience overheating problem. Urban green infrastructure (UGI) has proved effective in alleviating urban warming and enhancing thermal comfort. However, few research has been conducted to determine the proper UGI strategy across scales. Here, we propose a sustainable strategy for UGI planning by synthesizing the local climate zone (LCZ) concept and microclimate simulation, with the goal of ameliorating surface urban heat island (SUHI) and improving thermal comfort in cities. The LCZ map of Guangzhou showed that the major 'built-up land types' concentrated in the central area with high land surface temperature (LST) and intensities of SUHI. The circles (1-km diameter) identified as LCZ 2, 3, and 8 were recognized as planning areas by considering the intensities of SUHI and practicability. Afterward, the simulations of the UGI strategy scenarios at three randomly selected sample sites in LCZ 2, 3, and 8 were carried out using the ENVI-met model. The case study results in Guangzhou showed that increasing the green cover to 10% by adding grove and street trees could be the best adaptation strategy to ameliorate overheating, whereas adding extensive green roofs aggravated SUHI to a certain extent and showed minimal impacts on the thermal comfort at a pedestrian level. We show that it is promising to combine the LCZ concept and ENVI-met simulation in optimizing UGI toward urban overheating mitigation. • Multi-scale & discipline UGI strategy is needed to mitigate urban overheating. • A practical approach synthesizing LCZ concept and ENVI-met simulation was proposed. • Major built types concentrated in the central area with high intensities of SUHI. • Adding grove and street trees was the best adaptation strategy. • Application value of adopted approach was underlined for subsequent UGI studies. [ABSTRACT FROM AUTHOR] more...

Local microclimate and human thermal comfort are very sensitive to urban form. This study proposes an integrated strategy for urban infrastructures in different urban forms to investigate the importance of green-blue-grey infrastructure design in passive cooling and improving thermal comfort. Field measurements and model simulations have been conducted in three urban functional areas (i.e., a cultural square, park, and residential district) in Guangzhou. Twelve scenarios in two categories (i.e., adding and replacing) were investigated. The results show that, with the lowest coverage ratio of green infrastructure, the cultural square had a higher air temperature, which was 0.9 °C and 1.3 °C higher than the air temperatures in Ershadao park and the residential area, respectively. After removing the trees, the proportion of "extremely hot" thermal sensations in the park and residential area increased by 12.0% and 10.4%, respectively. Additionally, the types of infrastructures suitable for different urban forms are site specific. Specifically, in terms of cooling, the grey infrastructures performed better in the square and park, while the green infrastructures were most suitable for residential districts. The integrated scenarios (adding grey infrastructures and replacing green with grey infrastructures) revealed that the daily average air temperature in the square and park could be reduced by 0.63 °C and 0.26 °C, respectively, yet replacing the current green infrastructures with blue and grey infrastructures would aggravate heat stress in the residential area. The results of this study suggest that, in urban design, various infrastructures should be integrated and coordinated based on the characteristics of the specific urban form. This study can also assist urban designers in designing and planning green-blue-grey infrastructures that are more effective in maximizing thermal comfort in different urban functional areas. Image 1 • Cooling effects of blue, green and grey infrastructures were analyzed. • Optimal designs of infrastructures for different functional areas were proposed. • Grey infrastructure showed better cooling performance in square and park. • Green infrastructure was the most suitable type for residential district. • Integrated design of infrastructures should be applied in different functional areas. [ABSTRACT FROM AUTHOR] more...

Urban green infrastructures have been well recognized for their roles in providing ecosystem services in cities. However, their environmental performances have not been fully understood from a life-cycle perspective. In this study, we evaluated the life-cycle environmental performances and energy efficiencies of three types of green infrastructure, i.e. green roof, greenway, and grove that are increasingly built in cities. Our analysis covered all phases of the life-cycle including extraction and construction, use and maintenance, end-of-life, and transportation. Results confirm the environmental improvements of the green roof, greenway, and grove in most of the addressed impact categories. The energy saving in the use and maintenance phase contributed a significant part to these improvements, while the construction material in the extraction and construction phase had a dominant share in the environmental impacts. The grove and greenway showed better environmental performances than the green roof. The extensive use of compost for the greenway and grove could release toxic substances to the environment, and offset environmental improvements or even resulted in a negative consequence to EP of the greenway. The utilization of substrate and waste disposal for the green roof caused relatively high impacts on the environment. Sensitivity analysis shows a 50% reduction of the energy saving weakened the environmental improvements of the green roof, greenway and grove in all categories, and particularly exacerbated the environmental impacts on EP and CADP for the green roof, AP for the greenway and EP for the grove; and an increased waste recycling and reuse rates will greatly enhance the environmental improvements of the green roof. • Life-cycle environmental performances of three UGIs were evaluated and compared. • Robustness of results and impact of uncertainty factors were examined. • Grove and greenway showed better environmental performances than green roof. • 50% energy saving reduction weakened environmental improvements in all categories. • Increasing recycling and reuse rates improved green roof's environmental performance. [ABSTRACT FROM AUTHOR] more...