The fate of phosphorus in groundwater needs to be understood because phosphorus-rich groundwater is discharged into surface water bodies, which causes eutrophication, especially in urbanized areas. ...The present study investigated the spatial distributions and driving forces related to the groundwater phosphate levels in various aquifers in the Pearl River Delta (PRD), which has undergone three decades of urbanization, as well as the relationship between groundwater phosphate and arsenic was also discussed. The results showed that most of the high-phosphate (>1.53 mg/L) groundwater occurred in granular aquifers. The proportion of high-phosphate groundwater in granular aquifers was more than four times that in fissured aquifers, whereas high-phosphate groundwater was not observed in karst aquifers in the PRD. High-phosphate groundwater primarily occurred in urbanized areas in the PRD, and the proportion of high-phosphate groundwater had a significant positive correlation with the urbanization level. In granular aquifers, reductive environment and alkalization led to enrichment of the groundwater with phosphate. Anthropogenic sources such as wastewater from township-village enterprises (TVE) and animal wastes were the main sources of high-phosphate groundwater in urbanized areas, and the external input of phosphate enriched the groundwater arsenic levels in urbanized areas. By contrast, geogenic sources such as the release of phosphate from the reduction of Fe/Mn (hydr)oxides and the seawater intrusion accompanied by the release of phosphate from secondary minerals were mainly responsible for the occurrence of high-phosphate groundwater in peri-urban and non-urbanized areas, respectively. The high concentrations of both phosphate and arsenic in groundwater in fissured aquifers were mainly attributed to the infiltration of wastewater from TVEs. In contrast to the granular aquifers, the groundwater Eh and pH conditions were not conductive to the occurrence of high-phosphate groundwater in fissured aquifers.
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•Mostly high-phosphate groundwater occurs in granular aquifers in the PRD.•High-phosphate groundwater is positive correlation with the urbanization level.•Low Eh values and alkalization enhance groundwater phosphate in granular aquifers.•TVE wastewater and animal wastes are the main sources for high-phosphate groundwater.•External input of phosphate enhance groundwater arsenic enrichment in urbanized areas.
Township–village enterprises wastewater and animal wastes were the main sources of high-phosphate groundwater in study area. Low Eh and high pH enhanced groundwater phosphate in granular aquifers.
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•100%, 90.9%, and 78.2% drinkable groundwater in karst, fissured, and granular aquifer.•Groundwater quality in non-urbanized areas was much better than those in other ...areas.•Industrialization, one main driving force for groundwater quality in peri-urban areas.•Urbanization, one main driving force for groundwater quality in fissured aquifers.•Geologic forces control groundwater quality in non-urbanized areas.
Industrialization and urbanization expansion may change the groundwater quality in the Pearl River Delta (PRD). The aims of this study were to evaluate the groundwater quality in various aquifers and areas with different urbanization levels in the PRD, to extract the main impact indicators, and to discuss the driving forces for the groundwater quality. Nearly 400 groundwater samples were collected and 23 indicators were analyzed. In the PRD, 83% groundwater was drinkable (good-quality) by using a fuzzy synthetic evaluation method. Groundwater in karst aquifers was drinkable, and its quality was better than those in granular and fissured aquifers. In the latter two aquifer types, groundwater quality in non-urbanized areas was much better than those in peri-urban and urbanized areas. In granular aquifers, Mn + Fe, I− + Ni + Mn, and Mn + As + I− were the main impact indicators for poor-quality groundwater in urbanized areas, peri-urban areas, and non-urbanized areas, respectively. Correspondingly, reductive dissolution of Fe/Mn (oxy)hydroxides, infiltration of industrial wastewater and reductive dissolution of I− and Mn, and reductive dissolution of Mn, As, and I− were likely responsible for poor-quality groundwater in these areas, respectively. By contrast, in fissured aquifers, NO3−, NO3− + Pb, and I− were the main impact indicators for poor-quality groundwater in urbanized areas, peri-urban areas, and non-urbanized areas, respectively. Correspondingly, infiltration of domestic sewage, infiltration of domestic sewage and industrial wastewater, and mineralization of I-rich organic matter were probably responsible for poor-quality groundwater in these areas, respectively. Industrialization was one of the main driving forces for groundwater quality in granular and fissured aquifers in peri-urban areas, while urbanization was one of the main driving forces for groundwater quality in fissured aquifers in urbanized and peri-urban areas in the PRD.
Rare earth (RE) nanoparticles have attracted considerable attention due to their unique optical and magnetic properties associated with f‐electrons. The recent accomplishments in RE nanoparticle ...synthesis have aroused great interest of scientists to further explore their biomedical applications. This Research News summarizes recent achievements in controlled synthesis of magnetic and luminescent RE nanoparticles, surface modification, and toxicity studies of RE nanomaterials, and highlights state‐of‐the‐art in in vivo applications of RE nanoparticles.
Owing to the unique magnetic and optical properties associated with f‐electrons, rare earth (RE) nanoparticles show great potential for versatile in vivo applications, especially sensitive tumor imaging according to animal experiments. Recent achievements in the synthesis, surface modification, in vivo application, and toxicity of RE nanoparticles are summarized, and their perspectives for clinical applications are discussed.
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•Reveal geochemical process of PO4-rich groundwater based on natural background level.•Assessed NBL-PO4 in four groundwater units of the Pearl River Delta.•Groundwater NBL-PO4 in ...coastal-alluvial aquifer was >4 times that in other aquifers.•Co-release of PO4, HCO3, and Fe(II) accompanied with the elevated pH and decreased Eh.
Assessing natural background levels (NBLs) of groundwater chemical components is useful to the identification of geochemical factors controlling the origin of high levels of chemical components in groundwater. This study assessed the NBLs of phosphate in various groundwater units in the Pearl River Delta (PRD) where urbanization is a large-scale by the combination of a modified pre-selection method and Grubbs’ test, and discussed main geochemical processes controlling the origin of high levels of phosphate in groundwater. Here, the PRD is divided into four groundwater units according to its hydrogeological conditions. The modified pre-selection method consists of detected organic contaminants, the oxidation capacity, as well as the high levels of ammonium and nitrate in groundwater. Results showed that the NBL of phosphate in the coastal-alluvial aquifer was abnormal high (1.8 mg/L), and was >4 times that in other groundwater units. This is mainly attributed to the co-release of phosphate, bicarbonate, and Fe(II) accompanied with the elevated pH and decreased Eh, which resulted from the mineralization of organic matter accompanied with the reductive dissolution of Fe(III)-(hydr)oxides as well as the desorption of other secondary minerals such as aluminum oxyhydroxides in the overlaid marine stratum. Besides, unlike other groundwater units, the property of discharge area of the coastal-alluvial aquifer with more reducing environment also contributes the higher NBL of phosphate in the coastal-alluvial aquifer than in other groundwater units.
This paper proposes two schemes for indoor positioning by fusing Bluetooth beacons and a pedestrian dead reckoning (PDR) technique to provide meter-level positioning without additional ...infrastructure. As to the PDR approach, a more effective multi-threshold step detection algorithm is used to improve the positioning accuracy. According to pedestrians' different walking patterns such as walking or running, this paper makes a comparative analysis of multiple step length calculation models to determine a linear computation model and the relevant parameters. In consideration of the deviation between the real heading and the value of the orientation sensor, a heading estimation method with real-time compensation is proposed, which is based on a Kalman filter with map geometry information. The corrected heading can inhibit the positioning error accumulation and improve the positioning accuracy of PDR. Moreover, this paper has implemented two positioning approaches integrated with Bluetooth and PDR. One is the PDR-based positioning method based on map matching and position correction through Bluetooth. There will not be too much calculation work or too high maintenance costs using this method. The other method is a fusion calculation method based on the pedestrians' moving status (direct movement or making a turn) to determine adaptively the noise parameters in an Extended Kalman Filter (EKF) system. This method has worked very well in the elimination of various phenomena, including the "go and back" phenomenon caused by the instability of the Bluetooth-based positioning system and the "cross-wall" phenomenon due to the accumulative errors caused by the PDR algorithm. Experiments performed on the fourth floor of the School of Environmental Science and Spatial Informatics (SESSI) building in the China University of Mining and Technology (CUMT) campus showed that the proposed scheme can reliably achieve a 2-meter precision.
We report a disproportionation mechanism identified in the transformation of rod-like biicosahedral Au38(SCH2CH2Ph)24 to tetrahedral Au36(TBBT)24 nanoclusters. Time-dependent mass spectrometry and ...optical spectroscopy analyses unambiguously map out the detailed size-conversion pathway. The ligand exchange of Au38(SCH2CH2Ph)24 with bulkier 4-tert-butylbenzenethiol (TBBT) until a certain extent starts to trigger structural distortion of the initial biicosahedral Au38(SCH2CH2Ph)24 structure, leading to the release of two Au atoms and eventually the Au36(TBBT)24 nanocluster with a tetrahedral structure, in which process the number of ligands is interestingly preserved. The other product of the disproportionation process, i.e., Au40(TBBT)m+2(SCH2CH2Ph)24-m, was concurrently observed as an intermediate, which was the result of addition of two Au atoms and two TBBT ligands to Au38(TBBT)m(SCH2CH2Ph)24-m. The reaction kinetics on the Au38(SCH2CH2Ph)24 to Au36(TBBT)24 conversion process was also performed, and the activation energies of the structural distortion and disproportionation steps were estimated to be 76 and 94 kJ/mol, respectively. The optical absorption features of Au36(TBBT)24 are interpreted on the basis of density functional theory simulations.
Colorectal cancer (CRC) is the fourth leading cause of tumor-related deaths worldwide. In this study, we explored the in vivo effects of quercetin, a plant flavonol from the flavonoid group of ...polyphenols with antioxidant effects, on colon carcinogenesis induced by azoxymethane/dextran sodium sulfate (AOM/DSS). Thirty mice were randomly assigned into three groups: the control group, the AOM/DSS group, and the quercetin+AOM/DSS group. CRC was induced by AOM injection and a solution of 2% DSS in the drinking water. In the AOM/DSS-induced colon cancer mice model, quercetin treatment dramatically reduced the number and size of colon tumors. In addition, quercetin significantly restored the leukocyte counts by decreasing the inflammation caused by AOM/DSS. We also observed that the expression of oxidative stress markers, such as lipid peroxide (LPO), nitric oxide (NO), superoxide dismutase (SOD), glucose-6-phosphate (G6PD), and glutathione (GSH), could be reduced by quercetin, suggesting that the anti-inflammatory function of quercetin comes from its antioxidant effect. Moreover, potential biomarkers were identified with serum metabolite profiling. Increased levels of 2-hydroxybutyrate, 2-aminobutyrate, and 2-oxobutyrate and decreased levels of gentian violet, indole-3-methyl acetate, N-acetyl-5-hydroxytryptamine, indoxyl sulfate, and indoxyl were also found in the AOM/DSS-treated mice. However, quercetin treatment successfully decreased the levels of 2-hydroxybutyrate, 2-aminobutyrate, 2-oxobutyrate, endocannabinoids, and sphinganine and increased the levels of gentian violet, N-acetyl-5-hydroxytryptamine, indoxyl sulfate, and indoxyl. Together, our data demonstrated that quercetin could maintain relatively potent antitumor activities against colorectal cancer in vivo through its anti-inflammation effect.
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•Severe NO3− and NH4+contamination occur in granular and fissured aquifers.•Proportions of high-NO3− and high-NH4+: urbanized areas ≫ non-urbanized areas.•High-NO3− mainly from the ...leakage of township-village enterprises wastewater.•Housing construction enhanced NO3− contamination in newly urbanized areas.•High-NH4+ in urbanized areas mainly from mineralization of organic N in strata.
High nitrogen loading in aquifers is an important issue because of its harmful effects on human health; its origins are often complicated, especially in urbanized areas. This study aims to investigate the distributions of nitrate, nitrite, and ammonium in various aquifers in the Pearl River Delta, and to identify their main sources using hydrochemical and socioeconomic data and principal component analysis. The results show that groundwater with high nitrate (>20 mg/L as N), high nitrite (>1 mg/L as N), and high ammonium (>0.5 mg/L as N) appeared in 7.0%, 4.3%, and 20.5% of granular aquifers, and in 8.3%, 0.8%, and 5.3% of fissured aquifers, respectively, but did not appear in karst aquifers. The proportions of high-nitrate and high-ammonium groundwater in urbanized areas were nearly or more than twice those in non-urbanized areas. High nitrate levels in both granular and fissured aquifers originated mainly from the wastewater leakage of township-village enterprises during the industrialization. Urbanization accompanied by leakage of domestic sewage was another main driving force for high nitrate levels in fissured aquifers. Housing construction aggravated groundwater nitrate contamination in newly urbanized areas. Nitrate contamination in granular aquifers was reduced via denitrification in urbanized areas developed in 1988–1998, whereas that in fissured aquifers was increased by nitrification in urbanized areas developed before 1998. High ammonium levels in granular aquifers in urbanized areas originated mainly from mineralization of organic nitrogen in overlying aquitards, whereas that in peri-urban areas and non-urbanized areas originated mainly from urbanization accompanied by leakage of domestic sewage and irrigation using ammonium-rich river water, respectively. By contrast, high ammonium levels in fissured aquifers are attributed mainly to mineralization of organic nitrogen in carbon-rich strata, which was enhanced by urbanization accompanied by a relatively anoxic environment. Our study implies that nitrate and ammonium contaminations in this area will worsen in the future owing to a lack of effective control and treatment in these rapidly urbanized areas. Naturally originating high-ammonium groundwater in this area can be used as a nitrogen resource, for example, as a nitrogen fertilizer in agricultural irrigation.
A growing population accompanied by urbanization has increased groundwater resource demands in the Pearl River Delta (PRD) area, southern China, and a comprehensive understanding of the groundwater ...chemistry in the PRD is necessary. The aims of this study were to investigate the groundwater chemistry in various aquifers in the PRD on a regional scale and to discuss the factors that control the groundwater chemistries of different types of aquifers. In addition, the effect of the expansion of construction land on the groundwater chemistry was also taken into consideration in this study. Nearly 400 groundwater samples were collected and fourteen chemical parameters were investigated. The results show that natural factors, such as seawater intrusions, are mainly responsible for the higher concentrations of total dissolved solids, Na+, Mg2+, K+, and Cl−, in granular aquifers than those in fissured and karst aquifers. Similarly, higher concentrations of NH4+, Fe and Mn in granular aquifers than those in the other two types of aquifers are mainly ascribed to natural reduction. In contrast, human activities, such as the continuous irrigation of river water, upon granular aquifer are mainly responsible for the higher concentrations of Ca2+ and HCO3− in granular aquifers than those in other two types of aquifers. Urbanization and industrialization are the main driving forces for the frequently occurrences of NO3 and SO4 water types, respectively. Moreover, the number of water types in the PRD increased to 89 after the decades of urbanization. Factors that control groundwater chemistries in various aquifers were extracted. A four-factor model controlled the groundwater chemistry of granular aquifers, while two three-factor models controlled the groundwater chemistries of fissured and karst aquifers, respectively. The results of this study show that the expansion of construction land is a powerful driving force for the change of groundwater chemistry in the PRD.
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•Groundwater chemistry in the PRD after 3 decades of urbanization was investigated.•Emerge of NO3 and SO4 water types is driven by the urbanization and industrialization.•Quantity of water types was up to 89 after decades of urbanization.•Factors which control groundwater chemistry in various aquifers were extracted.
The purpose of the study is to investigate the relationships and potential impacts of environmental pollutants, human resources, GDP, sustainable power sources, financial assets, and SAARC countries ...from 1995 to 2022. Board cointegration tests, D-H causality, cross-sectional reliance (CSD), Saville and Holdsworth Restricted (SHL), and the DSK Appraisal Strategy were among the logical techniques employed to discover long-term connections between these components. Results demonstrate that GDP growth, renewable energy sources (REC), and environmental pollution (ENP) all contribute to SAARC countries' progress. However, future opportunities and HR are negatively impacted by increased ecological pollution. The results of the two-way causality test demonstrate a strong correlation between HR and future possibilities. Opportunities for the SAARC countries are closely related to the growth of total national output, the use of green electricity, and public support sources. Ideas for tackling future projects are presented in the paper's conclusion. These include facilitating financial development, reducing ecological pollution, financing the progress of human resources, and promoting the use of sustainable power sources.
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