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Quantitative assessment of sediment delivery and retention in four watersheds in the Godavari River Basin, India, using InVEST model — an aquatic ecosystem services perspective Full text
2022
Kantharajan, Ganesan | Govindakrishnan, Panamanna Mahadevan | Singh, Rajeev K. | Estrada-Carmona, Natalia | Jones, Sarah K. | Singh, Achal | Mohindra, Vindhya | Kumar, Nallur Kothanda Raman Krishna | Rana, Jai C. | Jena, Joy Krushna | Lal, Kuldeep Kumar
Impact of urbanisation (trends) on runoff behaviour of Pampulha watersheds (Brazil) Full text
2019
Seidl, Martin | Hadrich, Bilel | Palmier, Luiz | Petrucci, Guido | Nascimento, Nilo | Laboratoire Eau Environnement et Systèmes Urbains (LEESU) ; AgroParisTech-École nationale des ponts et chaussées (ENPC)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12) | Hydraulic and water resource engineering department (EHR) ; Universidade Federal de Minas Gerais = Federal University of Minas Gerais [Belo Horizonte, Brazil] (UFMG) | Finep Brazil | UFMG Brazil / ENPC France
International audience | The paper presents an analysis of runoff behaviour of four urban catchments between the municipalities of Belo Horizonte and Contagem in Brazil, linked to their land use. Two years of online measurement of flow data, combined with spatial analysis, was linked through runoff modelisation with EPA SWMM. The coefficients of Nash obtained varying between 0.75 and 0.87 demonstrated an adequate modelling approach. A 1-year rain series was applied to evaluate the runoff behaviour of actual land cover and that of 2002. The peak flows normalised to watershed surfaces revealed as the most urbanised (85%) watershed Ressaca with 178 L/ha/s, three times more runoff intensive than the least urbanised (41%) Mergulhão with 67 L/ha/s. Statistical analysis of land cover data and modelling results on watershed and sub-watershed level showed main correlations between hydrological parameters such as peak flow, average event flow and restitution time, but also between land cover and runoff coefficient. This approach gave a linear relation between runoff and green surface, with a runoff coefficient of 0.86 for fully urbanised zone and 0.43 for full “green” cover. Prospective simulation with actual urbanisation rates varying from 4 to 34 ha/year suggested an increase between 6 and 18% of the flows and a possible end of urbanisation within the next two to three decades. These findings should contribute to a better understanding of hydrological impact of Belo Horizonte urbanisation and to the restauration of its Lake Pampulha.
Show more [+] Less [-]Microplastics in freshwater: A global review of factors affecting spatial and temporal variations Full text
2022
Talbot, Rebecca | Chang, Heejun
Microplastics are a pollutant of growing concern, capable of harming aquatic organisms and entering the food web. While freshwater microplastic research has expanded in recent years, much remains unknown regarding the sources and delivery pathways of microplastics in these environments. This review aims to address the scientific literature regarding the spatial and temporal factors affecting global freshwater microplastic distributions and abundances. A total of 75 papers, published through June 2021 and containing an earliest publication date of October 2014, was identified by a Web of Science database search. Microplastic spatial distributions are heavily influenced by anthropogenic factors, with higher concentrations reported in regions characterized by urban land cover, high population density, and wastewater treatment plant effluent. Spatial distributions may also be affected by physical watershed characteristics such as slope and elevation (positive and negative correlations with microplastic concentrations, respectively), although few studies address these factors. Temporal variables of influence include precipitation and stormwater runoff (positive correlations) and water flow/discharge (negative correlations). Despite these overarching trends, variations in study results may be due to differing scales or contributing area delineations. Thus, more rigorous and standardized spatial analytical methods are needed. Future research could simultaneously evaluate both spatial and temporal factors and incorporate finer temporal resolutions into sampling campaigns.
Show more [+] Less [-]Exploring common factors influencing PM2.5 and O3 concentrations in the Pearl River Delta: Tradeoffs and synergies Full text
2021
Wu, Jiansheng | Wang, Yuan | Liang, Jingtian | Yao, Fei
Particulate matter with an aerodynamic equivalent dimeter less than 2.5 μm (PM₂.₅) and ozone (O₃) are major air pollutants, with coupled and complex relationships. The control of both PM₂.₅ and O₃ pollution requires the identification of their common influencing factors, which has rarely been attempted. In this study, land use regression (LUR) models based on the least absolute shrinkage and selection operator were developed to estimate PM₂.₅ and O₃ concentrations in China's Pearl River Delta region during 2019. The common factors in the tradeoffs between the two air pollutants and their synergistic effects were analyzed. The model inputs included spatial coordinates, remote sensing observations, meteorological conditions, population density, road density, land cover, and landscape metrics. The LUR models performed well, capturing 54–89% and 42–83% of the variations in annual and seasonal PM₂.₅ and O₃ concentrations, respectively, as shown by the 10-fold cross validation. The overlap of variables between the PM₂.₅ and O₃ models indicated that longitude, aerosol optical depth, O₃ column number density, tropospheric NO₂ column number density, relative humidity, sunshine duration, population density, the percentage cover of forest, grass, impervious surfaces, and bare land, and perimeter-area fractal dimension had opposing effects on PM₂.₅ and O₃. The tropospheric formaldehyde column number density, wind speed, road density, and area-weighted mean fractal dimension index had complementary effects on PM₂.₅ and O₃ concentrations. This study has improved our understanding of the tradeoff and synergistic factors involved in PM₂.₅ and O₃ pollution, and the results can be used to develop joint control policies for both pollutants.
Show more [+] Less [-]Estimation of nitrate pollution sources and transformations in groundwater of an intensive livestock-agricultural area (Comarca Lagunera), combining major ions, stable isotopes and MixSIAR model Full text
2021
Torres Martínez, Juan Antonio | Mora, Abrahan | Mahlknecht, Jürgen | Daesslé, Luis W. | Cervantes-Avilés, Pabel A. | Ledesma-Ruiz, Rogelio
The identification of nitrate (NO₃⁻) sources and biogeochemical transformations is critical for understanding the different nitrogen (N) pathways, and thus, for controlling diffuse pollution in groundwater affected by livestock and agricultural activities. This study combines chemical data, including environmental isotopes (δ²HH₂O, δ¹⁸OH₂O, δ¹⁵NNO₃, and δ¹⁸ONO₃), with land use/land cover data and a Bayesian isotope mixing model, with the aim of reducing the uncertainty when estimating the contributions of different pollution sources. Sampling was taken from 53 groundwater sites in Comarca Lagunera, northern Mexico, during 2018. The results revealed that the NO₃⁻ (as N) concentration ranged from 0.01 to 109 mg/L, with more than 32% of the sites exceeding the safe limit for drinking water quality established by the World Health Organization (10 mg/L). Moreover, according to the groundwater flow path, different biogeochemical transformations were observed throughout the study area: microbial nitrification was dominant in the groundwater recharge areas with elevated NO₃⁻ concentrations; in the transition zones a mixing of different transformations, such as nitrification, denitrification, and/or volatilization, were identified, associated to moderate NO₃⁻ concentrations; whereas in the discharge area the main process affecting NO₃⁻ concentrations was denitrification, resulting in low NO₃⁻ concentrations. The results of the MixSIAR isotope mixing model revealed that the application of manure from concentrated animal-feeding operations (∼48%) and urban sewage (∼43%) were the primary contributors of NO₃⁻ pollution, whereas synthetic fertilizers (∼5%), soil organic nitrogen (∼4%), and atmospheric deposition played a less important role. Finally, an estimation of an uncertainty index (UI90) of the isotope mixing results indicated that the uncertainties associated with atmospheric deposition and NO₃⁻−fertilizers were the lowest (0.05 and 0.07, respectively), while those associated with manure and sewage were the highest (0.24 and 0.20, respectively).
Show more [+] Less [-]Land use associated with Cryptosporidium sp. and Giardia sp.in surface water supply in the state of São Paulo, Brazil Full text
2020
Breternitz, Bruna Suellen | Barbosa da Veiga, Denise Piccirillo | Pepe Razzolini, Maria Tereza | Nardocci, Adelaide Cássia
Land use/Land cover (LULC) associated with Cryptosporidium sp. and Giardia sp. quantification and distribution can provide identification of the environmental circulation patterns of these parasites. The aim of this research was to relate the occurrence and circulation of these parasites to the LULC watershed with poor sanitation infrastructure and livestock as important economic activity. The study involved 11 municipalities in the state of São Paulo, located in southeastern Brazil. Sampling was carried out at the catchment sites of each water supply on a monthly basis, starting in December 2014 and lasting until November 2015, totalizing 128 samples. Protozoans were quantified according to the 1623.1 US. EPA Method. For watershed delimitation, the hydrographic network was extracted from the hydrology tool of ArcGIS 10.1. The frequency of occurrence of these pathogens and the high concentrations were evidenced in the municipality with the largest urban area (16.2%) and intense livestock activity (39%) near the catchment site. The municipality that showed the lowest frequency of occurrence presented the smallest urban area (0.87%) and absence of livestock activity near the catchment site. The high concentration of pathogens suggests a correlation between the impact on water supply networks and river basin degradation caused by urban activity and livestock.
Show more [+] Less [-]Urbanization significantly impacts the connectivity of soil microbes involved in nitrogen dynamics at a watershed scale Full text
2020
Zhang, Yan | Ji, Guodong | Wu, Tong | Qiu, Jiangxiao
As one of the most dominant ecosystems of urban green space, turfgrasses provide a wide range of ecosystem services. However, little is known about the interactions of microbial communities in turfgrass soils and how these interactions respond to expanding development of impervious surfaces during watershed urbanization. In this study, we analyzed bacterial communities and their co-occurrence patterns in turfgrass soils along an urbanization gradient as measured by the proportion of impervious surfaces in Jiulong River watershed in Fujian, China. Results show that the diversity and network size of bacterial communities negatively associated with impervious surfaces. The bacterial communities showed non-random co-occurrence patterns, with more intra-module connections observed for urbanized networks. The co-occurrence network with distinct modules of soil samples with contrasting land cover imperviousness suggested different functional organizations with altered microbial nitrogen processes. Structural equation modelling revealed that watershed impervious surfaces had indirect impacts on microbial connectivity by altering soil properties, including pH, temperature, moisture, C/N and nitrate (NO₃⁻). Moreover, impervious surfaces affected microbial connectivity far more than human population density. Our study highlights the significance of human disturbances in affecting microbial interactions and assemblies in turfgrass ecosystems through impervious surfaces and provides benefits for sustainable urban planning and management at a watershed scale.
Show more [+] Less [-]Comparing and modeling sedimentary profiles of elemental carbon and polycyclic aromatic hydrocarbons between early- and newly-urbanized areas in Shanghai Full text
2019
Yang, Jing | Yang, Yi | Liu, Min | Meng, Xiang-Zhou | Huang, Yan-Ping | Zhang, Xi | Ma, Fen-Qiong
Rapid urbanization created unique urban environment with a characteristic of dramatic modification of land cover, consequently causing profound perturbations in the transport and fate of pollutants in urban ecosystem. Taking a hyper-urbanization city (Shanghai) as an example to reveal the influence of urbanization development on pollutant footprint, this study reconstructed and compared historical evolutions of elemental carbon (EC) and polycyclic aromatic hydrocarbons (PAHs) based on two lake sediment cores (DSL: Dianshan Lake; LXL: Luxun Lake) from early- and newly-urbanized areas, respectively. Historical fluxes of EC and total PAH (Σ₁₆PAHs) showed similar and sharply fluctuant increases occurring after the 1950s in the DSL core later than the LXL core after the 1900s. In modern times (after 2000), the mean fluxes of EC and Σ₁₆PAHs in the LXL core were 2.68- and 1.38-fold greater than those in the DSL core, respectively, indicating the stronger influence from more intensive human activities and longer industrial history in early urbanized area. Based on the significant correlations among socioeconomic factors with EC and Σ₁₆PAH fluxes, the extended STIRPAT (stochastic impacts by regression on population, affluence and technology) models were successfully constructed, revealing that significance of these driving factors were in the order of population > the proportion of heavy industry > coal consumption > gross domestic product (GDP) per capita > vehicle amount. In general, the obvious discrepancy in historical stage and intensity of sedimentary EC and PAH accumulations implied that some newly fast-developing cities still have a chance to adjust urban development strategy to avoid more serious pollution.
Show more [+] Less [-]Environmental fate and behavior of persistent organic pollutants in Shergyla Mountain, southeast of the Tibetan Plateau of China Full text
2014
Zhu, Nali | Schramm, Karl-Werner | Wang, Thanh | Henkelmann, Bernhard | Zheng, Xiaoyan | Fu, Jianjie | Gao, Yan | Wang, Yawei | Jiang, Guibin
Pristine mountains are ideal settings to study transport and behavior of persistent organic pollutants (POPs) along gradients of climate and land cover. The present work investigated the concentrations and patterns of 28 organochlorine pesticides (OCPs), 25 polychlorinated biphenyl (PCBs), 13 polybrominated diphenyl ethers (PBDEs), and 3 hexabromocyclododecane (HBCDs) isomers in the air of the Shergyla Mountain, southeastern Tibetan Plateau. Endosulfan І, hexachlorobenzene, pentachlorobenzene, hexachlorocyclohexanes and dichlorodibenzotrichloroethane and its degradation products (DDTs) were the predominant compounds while PBDEs and HBCDs showed the lowest background concentrations. Most of the target POPs had significantly higher concentrations in summer than those in winter. Increasing trends of the concentrations of DDTs and endosulfan were found with increasing altitude on the western slope in the Shergyla Mountain. Potential forest filter effect was observed based on the lower air concentrations of the target POPs in the forest than the ones out of the forest.
Show more [+] Less [-]Tools for determining critical levels of atmospheric ammonia under the influence of multiple disturbances Full text
2014
Pinho, P. | Llop, E. | Ribeiro, M.C. | Cruz, C. | Soares, A. | Pereira, M.J. | Branquinho, C.
Critical levels (CLEs) of atmospheric ammonia based on biodiversity changes have been mostly calculated using small-scale single-source approaches, to avoid interference by other factors, which also influence biodiversity. Thus, it is questionable whether these CLEs are valid at larger spatial scales, in a multi- disturbances context. To test so, we sampled lichen diversity and ammonia at 80 sites across a region with a complex land-cover including industrial and urban areas. At a regional scale, confounding factors such as industrial pollutants prevailed, masking the CLEs. We propose and use a new tool to calculate CLEs by stratifying ammonia concentrations into classes, and focusing on the highest diversity values. Based on the significant correlations between ammonia and biodiversity, we found the CLE of ammonia for Mediterranean evergreen woodlands to be 0.69 μg m−3, below the previously accepted value of 1.9 μg m−3, and below the currently accepted pan-European CLE of 1.0 μg m−3.
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