Algal blooms caused by high concentrations of nutrients (especially phosphorus) limit the use of recycled water (RW) for replenishing landscape ponds in the context of global water scarcity. Previous ...studies have demonstrated that alum sludge is a low cost phosphorus sorption medium, which could potentially be applied in constructed wetlands and sewage treatment plants. However, whether alum sludge can be used for algae inhibition in reclaimed water urban landscape ponds (RWULPs) should be explored. In this study, phosphorus removal and algae inhibition by alum sludge were investigated in a RWULP in China. The results highlight that there is a serious risk of algal blooms in RWULPs. The algal density was found to be 1.58 × 105 cell·mL−1, which is 6.84 times higher than that of the surface water ponds. The algal blooms presented a Cyanophyta–Chlorophyta–Bacillariophyta-type, and the dominant algae species were Microcystis flos-aquae (Wittr.) Kirchner, Chlorella vulgaris, and Scenedesmus quadricauda. Moreover, the removal rate of phosphorus by alum sludge was as high as 98% and eventually leads to phosphorus stress, which has an important effect on algae growth and algae inhibition rate of 80%. In addition, the proportion of phosphorus and nitrogen in the adsorbed alum sludge increased by 3.12% and 0.32%, respectively, and Al3+ was reduced by only 2.18%. Alum sludge is a potential inhibitor of algae in RWULPs that does not negatively impact the environment. These results are of great importance in algal bloom control of RWULPs and may help alleviate the problem of urban water resource scarcity.
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•Algal bloom in reclaimed water urban landscape ponds (RWULPs).•Alum sludge was first used to control algal blooms in RWULPs.•Algae growth was inhibited by phosphorus stress.•Provide solutions for alleviating urban water shortage.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Residents’ sentiments are a quantitative indicator of human feelings, which is useful for optimizing urban residential environments. Little is known about the spatiotemporal variations and potential ...drivers of sentiment based on big data. A total of 221,104 Weibo social media data were used to quantify daily sentiment in the Beijing metropolitan area during the COVID-19 pandemic from January 1, 2021 to March 8, 2022. Deep-learning natural language processing was used to extract this dataset to investigate the spatiotemporal sentiment patterns. The density of roads and buildings, normalized difference vegetation index (NDVI), population, sky visibility factor, daily land surface temperature (LST), daily precipitation, and daily air pollution concentrations (CO, NO2, PM2.5, SO2, and O3) were explored as potential drivers of sentiment. Results show that (1) the holiday sentiment was 1.31% higher than on weekends and 4.61% higher than on weekdays. Extreme precipitation, air pollution, and COVID-19 lockdown measures have reduced sentiment. (2) The sentiment in spring was found to be the highest. The numbers of functional zones with high sentiment values (>0.8) in spring were 13.59%, in summer 34.48%, and in autumn 14.71%. (3) Sentiment was highest under conditions of moderate greenness (0.4<NDVI<0.6) and comfortable daily temperature (25 °C < LST<30 °C). (4) Sentiment was negatively associated with daily air pollutants, such as PM2.5, NO2, and CO. This paper presents the effectiveness of sentiment quantification based on social media data and deep-learning techniques. The results provide practical implications and support decisions for sustainable urban health development.
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•Residents' sentiments were quantified by deep learning and social media data.•Holiday's sentiments were 1.31% higher than weekend's and 4.61% higher than weekday's.•Moderate greenness and comfortable temperature can enhance sentiments.•PM2.5, NO2, and CO can decrease the sentiments significantly.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Urban park patronage is intimately linked to the thermal comfort level perceived by visitors. This study quantified the effects of nine park-design and urban-landscape parameters on air temperature ...and relative humidity in summer by deploying 100 sensors in 14 urban parks in Hong Kong. The field data were compared with a reference weather station and analysed with multiple regression. The sampled parks were on average 0.2 °C warmer and 1.7% less humid than the reference. A notable temperature reduction (mean = 0.6 °C and max. = 4.9 °C) was only observed in the largest park in Hong Kong. The daily variations in cooling and humidifying magnitudes were strongly dependent on background temperature. The distance from sea, shrub cover, tree cover and sky view factor were significant parameters that controlled temperature and relative humidity. Mean temperature could be predicted to cool by 0.6 °C if the park was 1 km closer to the sea. For every 10% increase in shrub and tree covers, mean temperature would drop by 0.07 and 0.04 °C respectively. Larger parks with good coverage of woody vegetation should be developed to improve urban microclimate within parks and mediate the warming effect of nearby built-up areas.
•Fourteen urban parks in Hong Kong were on average 0.2 °C warmer than reference site.•The largest park produced a mean and max. cooling of 0.6 and 4.6 °C respectively.•Temperature and RH in parks were strongly controlled by background weather.•Proximity to sea, shrub cover, tree cover and SVF significantly affect temperature.•Temperature could be cooled by 0.6 °C if the park was 1 km closer to the sea.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Urban landscape lakes (ULLs) are important environmental elements in most cities. In order to understand the current situation of ULLs in China and formulate proper strategies to improve their ...landscape quality to meet public desire for water-front enjoyment, a study was conducted of 189 ULLs widely distributed in 26 provinces of China, based on existing data and field surveys. These ULLs were firstly categorized according to their topographic features, climatic zones, and water replenishment sources. Lake water quality was evaluated considering both single factors and a comprehensive pollution index (CPI). Results show that if the Chinese Surface Water Quality Standard was used as the sole criteria, about 60% of the ULLs investigated could not meet the lowest requirement. Excessive total nitrogen (TN) concentration was the most limiting factor especially when reclaimed water was the replenishment source. The differences in topographic and climatic conditions to a certain extent affected the availability of replenishment water sources but no significant correlation was identified with the single water quality factors or CPI. However, when public satisfaction was introduced in the evaluation of the ULLs' landscape effect, it was found that the water transparency in terms of Secchi Depth (SD) correlated well with people's appreciation of water landscape.
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•189 urban landscape lakes (ULLs) in 26 provinces over China were investigated.•These ULLs were diagnosed according to replenishment condition and water quality.•Several indices were compared for characterizing landscape water quality.•Water transparency (SD) was found to correlate well with public perception.•SD was evidenced as suitable indicator for characterizing the quality of ULLs.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Although PM2.5 poses a serious threat to public health, the role of urban form in influencing concentrations of this air pollutant is unresolved. Ridge regression was employed to investigate ...relationships between satellite-derived estimates of PM2.5 concentrations and the urban form of 350 cities in the rapidly urbanizing Yangtze River Delta (YRD) of eastern China. The cities were stratified by population into small (<500,000), medium-sized (500,000–1,000,000), and large (>1,000,000), and urban circularity, fragmentation, and compactness were measured from 1998 to 2015. Circularity was not a statistically significant predictor of PM2.5 concentrations, except for maxima in large cities. Although fragmentation was strongly negatively correlated with mean and maximum PM2.5 concentrations for all cities, compactness was positively associated with mean and maximum PM2.5 concentrations only in small and medium-sized cities. Urban form thus had a relatively stronger impact on PM2.5 concentrations in cities that were not yet large. After controlling for population, land area, and climate, more sprawled cities had lower PM2.5 concentrations than their more spatially compact counterparts. These findings indicate that planning agencies in the YRD should encourage moderately scattered and polycentric urban development rather than compact, monocentric growth.
•We measured urban form by “circularity”, “fragmentation”, and “compactness”.•We quantified the impact of urban form on PM2.5 for different-sized cities in the YRD.•We compared the impact of urban form on air quality in China and the US.•We proposed optimized urban form characteristics to mitigate PM2.5 pollution.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Bacteria play a critical role in environmental and ecological processes in river ecosystems. We studied the bacterial community in the Ganjiang River, a major tributary of the Yangtze River, as it ...flowed through Nanchang, the largest city in the Ganjiang River basin. Water was sampled at five sites monthly during the wet season, and the bacterial community was characterized using Illumina high-throughput sequencing. A total of 811 operational taxonomic units (OTUs) were observed for all samples, ranging from 321 to 519 for each sample. The bacterial communities were maintained by a core of OTUs that persisted longitudinally and monthly. Actinobacteria (41.17% of total sequences) and Proteobacteria (31.80%) were the dominant phyla, while Firmicutes (mostly genus Lactococcus) became most abundant during flooding. Temperature and flow rate, rather than water chemistry, were the main factors influencing the bacterial community in river water. Temperature was the best individual parameter explaining the variations in OTU abundance, while flow rate was the best individual parameter explaining the variations in phylum abundance. Except for Proteobacteria, the relative abundance of bacterial phyla did not differ significantly between sites, and the degrees of influence of urban landscape on the bacterial community were estimated to be 17%–34%.
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•Actinobacteria and Proteobacteria are the dominant phyla in river water.•Firmicutes (mostly genus Lactococcus) is the dominant phylum during flooding.•Temperature and runoff are the main influencing factors of bacterial community.•The influence of urban landscape on the bacterial community is about 17%–34%.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Lawns have long been a primary feature of residential landscapes in the United States. However, as population growth in urban areas continues to rise, water conservation is becoming a key priority ...for many municipalities. In recent years, some municipalities have begun to offer rebate programs which incentivize removal of turfgrass areas and conversion to alternative ‘water-efficient’ landscapes, with the goal of reducing outdoor water use. The environmental impacts and changes to ecosystem services associated with such landscape alterations are not well understood. Therefore, a 2-year continuous research project was conducted at the Urban Landscape Runoff Research Facility at Texas A&M University to evaluate rainfall capture and runoff volumes associated with several commonly used residential landscape types (including, St. Augustine grass Lawn, Xeriscaping, Mulch, Artificial Turf, and Sand-capped Lawn) and to characterize the flow dynamics of surface runoff in relation to rainfall intensity for each landscape. The results demonstrate that runoff dynamics differ between landscapes, but also change over time as the newly converted landscapes become established. Following the initial months of establishment, the effects of landscape type on runoff volumes were significant, with Artificial Turf and Xeriscaping generating greater runoff volumes than Mulch and St. Augustine grass Lawns for most runoff events, which is partially due to the low infiltration rate of such landscapes. Overall, Artificial Turf and Xeriscaping showed the greatest cumulative runoff volumes (>400 L m−2), whereas Water Efficient- Mulch, Sand-capped Lawn and St. Augustine grass Lawn had a significantly lower cumulative runoff volumes, ranging from 180 to 290 L m−2. Information from this research should be useful to municipalities, water purveyors, and homeowner associations as they weigh the long-term hydrological impacts of lawn removal and landscape conversion programs.
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•Pressure to save water has caused a shift from lawns to water-efficient landscapes.•Runoff volumes were affected by landscape, rainfall, and age of the landscape.•Grass lawns showed greater runoff control than artificial turf and xeriscaping.•Sand-capped lawn further enhanced control of runoff.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Gaseous carbon exchange at the water–air interface of rivers and lakes is an essential process for regional and global carbon cycle assessments. Many studies have shown that rivers surrounding urban ...landscapes can be hotspots for greenhouse gas (GHG) emissions. Here we investigated the variability of diffusive GHG (methane CH4 and carbon dioxide CO2) emissions from rivers in different landscapes (i.e., urban, agricultural and mixed) and from lakes in Suzhou, a highly urbanized region in eastern China. GHG emissions in the Suzhou metropolitan water network followed a typical seasonal pattern, with the highest fluxes in summer, and were primarily influenced by temperature and dissolved oxygen concentration. Surprisingly, lakes were emission hotspots, with mean CH4 and CO2 fluxes of 2.80 and 128.89 mg m−2 h−1, respectively, translating to a total CO2-equivalent flux of 0.21 g CO2-eq m−2 d−1. The global warming potential of urban and mixed rivers (0.19 g CO2-eq m−2 d−1) was comparable to that for lakes, but about twice the value for agricultural rivers (0.10 g CO2-eq m−2 d−1). Factors related to the high GHG emissions in lakes included hypoxic water conditions and an adequate nutrient supply. Riverine CH4 emissions were primarily associated with the concentrations of total dissolved solids (TDS), ammonia‑nitrogen and chlorophyll a. CO2 emissions in rivers were mainly closely related to TDS, with suitable conditions allowing rapid organic matter decomposition. Compared with other types of rivers, urban rivers had more available organic matter and therefore higher CO2 emissions. Overall, this study emphasizes the need for a deeper understanding of the impact of GHG emissions from different water types on global warming in rapidly urbanizing regions. Flexible management measures are urgently needed to mitigate CO2 and CH4 emissions more effectively in the context of the shrinking gap between urban and rural areas with growing socio-economic development.
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•CH4 and CO2 emissions in the urbanized water network showed a typical seasonal pattern with less spatial variability.•An adequate nutrient supply was a key factor in high greenhouse gas emissions from water bodies in urbanized areas.•Lakes were more likely to be hotspots for greenhouse gas emissions than rivers in metropolitan water networks.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Previous archaeological mapping work on the successive medieval capitals of the Khmer Empire located at Angkor, in northwest Cambodia (∼9th to 15th centuries in the Common Era, C.E.), has identified ...it as the largest settlement complex of the preindustrial world, and yet crucial areas have remained unmapped, in particular the ceremonial centers and their surroundings, where dense forest obscures the traces of the civilization that typically remain in evidence in surface topography. Here we describe the use of airborne laser scanning (lidar) technology to create high-precision digital elevation models of the ground surface beneath the vegetation cover. We identify an entire, previously undocumented, formally planned urban landscape into which the major temples such as Angkor Wat were integrated. Beyond these newly identified urban landscapes, the lidar data reveal anthropogenic changes to the landscape on a vast scale and lend further weight to an emerging consensus that infrastructural complexity, unsustainable modes of subsistence, and climate variation were crucial factors in the decline of the classical Khmer civilization.
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BFBNIB, NMLJ, NUK, PNG, SAZU, UL, UM, UPUK
Besides the increase of mobile communication services and providers in Peru, base stations (BS) have grown greatly without considering their visual impact. The characterization and evaluation of the ...visual impact from base stations to urban landscapes was carried out in the district of San Miguel, located in Lima, Peru. This district has a number of base stations suitable to conduct a pilot study. National and international regulations in force were reviewed, and the Manual for Camouflage of Radio Stations from Bogota DC, Colombia, was chosen as the basis for the visual impact evaluation. Then, a field study of mobile base stations located in the district of San Miguel was accomplished. After that, the matrices for evaluating the visual impact to each of the BS were applied. According to the evaluation, 12 BS (20.3 %) have a low visual impact, 42 BS (71.2 %) have a medium visual impact, and 5 BS (8.5 %) have a high visual impact. So, more than 90 % of the BS in San Miguel has low or medium visual impact.
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