The abandoned smelters have caused serious hazards to the surrounding environment and residents. Taking an abandoned zinc smelter in southern China as an example, a total of 245 soil samples were ...collected to study spatial heterogeneity, source apportionment, and source-derived risk assessment of heavy metal(loid)s (HMs) in the region. The results showed that the mean values of all HMs concentrations were higher than the local background values, with Zn, Cd, Pb, and As contamination being the most serious and their plume penetrating to the bottom layer. Four sources were identified by principal component analysis and positive matrix factorization, with their contributions to the HMs contents ranked as: surface runoff (F2, 63.2%) > surface solid waste (F1, 22.2%) > atmospheric deposition (F3, 8.5%) > parent material (F4, 6.1%). Among these, F1 was a determinant source of human health risk with a contribution rate of 60%. Therefore, F1 was considered to be the priority control factor, but it only accounted for 22.2% of HMs contents contribution. Hg dominated the ecological risk with a contribution of 91.1%. Pb (25.7%) and As (32.9%) accounted for the non-carcinogenic risk, while As (95%) dominated the carcinogenic effect. The spatial characteristics of human health risk values derived from F1 indicated that high-risk areas were mainly distributed in the casting finished products area, electrolysis area, leaching-concentration area, and fluidization roasting area. The findings highlight the significance of priority control factors (including HMs, pollution sources and functional areas) for consideration in the integrated management of this region, thus saving costs for effective soil remediation.
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•CA, PCA and PMF models were used to quantify the pollution sources precisely.•Surface solid waste sources are a priority control factor due to their significant contribution to health risks (60%).•The spatial patterns of HHR from surface solid waste sources were distributed in the CFPA, EA, LCA and FRA zones.
A study was carried out to examine effects of calcium ferrite slag on dephosphorization of hot metal in the steelmaking BOF, with aims to pick up the speed of slag-forming, increase the slag dumping ...rate. Laboratory tests using a resistance furnace were performed to examine melting characteristics of calcium ferrite pellets, designed with the optimum ratio of iron oxides (total Fe 55%) to CaO of 3:1. The pellets were put in crucibles with furnace temperature held in the range of 1250–1350 °C for 10 min. The results showed that the melting of pellets was nearly completed at 1250°C and main mineral phases, detected by XRD, in the melted samples were CaO•Fe2O3 and 2CaO•Fe2O3. Based on results of the laboratory tests, experiments of full scale were performed using a converter of 120t, charging the hot metal with C 3.46–6.81%, Si 0.1–1.16%, Mn 0.12–0.30%, P 0.10–0.18%, S 0.017–0.13% and temperature of 1234–1430 °C. For the 13 test heats with 6 min of oxygen blowing, the rate of dephosphorization and phosphorus distribution ratio reached to 50–60% and 55.9, respectively, when the calcium ferrite pellets were charged. Averaged slag basicity 1.5–2.0, slag melting point 1280–1310℃, slag viscosity 0.5 pa.s were obtained for the BOF heats adding the calcium ferrite pellet, which ensured the slag foaming height controlled at 2.5–3.0 m during the early stages of the blow. Using above smelting process has increased the rate of slag dumping controlled at 50–70% and enhanced the rate of hot metal dephosphorization over 90%.
Heavy metals (HMs) pollution is a universal and complex problem at lead smelting sites. Further understanding on the distribution, coexistence relationship and occurrence form of multi-metals in ...soils should be taken prior to restoration on the contaminated sites. In this study, 222 soil samples in a typical abandoned lead smelting site were investigated to understand the spatial distribution and geochemical partitioning of HMs. The results showed that soil quality was seriously threatened by As, Pb and Cd, which expressed high spatial heterogeneity. Integration of sequential extraction, X-ray photoelectron spectroscopy and mineral liberation analysers were employed to qualify the geochemical partitioning of HMs. The data showed that Pb and As were mainly partitioned in the reducible phase and residue phase, where the maximum of As were 18% and 79%, and the maximum of Pb were 31% and 64%, respectively, whilst Cd was mainly partitioned with residue phase (about 25%) and weakly acid soluble phase (about 18%). Paulmooreite was the major important mineral host for Pb and As, whereas Cd predominantly existed in willemite. These minerals containing HMs could usually with Fe reside in the octahedral layer of clay minerals such as montmorillonite, and may also reside in the interlayer. Quartz, montmorillonite and goethite were closely associated with HMs minerals in contaminated soils, which limited vertical migration of HMs and potential risks to groundwater. The results enhanced the understanding of spatial distribution and occurrence behavior of HMs, whilst providing potential benefits to heavy metal stabilization and risks control at abandoned non-ferrous metal smelting sites.
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•The spatial distribution characteristics of Pb and As are similar.•Paulmooreite was the major important mineral host for Pb and As.•Willemite was the major important mineral host for Cd.•Quartz montmorillonite and goethite were closely associated with HMs minerals.
Contaminated sites pose a significant risk to human health and the regional environment. A comprehensive study was dedicated to improving the understanding of the contamination condition of a ...smelting site by integrating multi-source information through 3D visualization techniques. The results showed that 3D visualization reveals excellent potential for application in the environmental studies to finely depict contamination in soils and establish relationships with geological features, hydrological conditions, and sources of contamination. The contamination plume model revealed that the soil environment at the site was seriously threatened by toxic metals, and dominated by multi-metal contamination, with contamination soil volume ranked as Cd > As > Pb> Zn > Hg. The stratigraphic model revealed the heterogeneous geological conditions of the site and identified the mixed fill layer as the primary remediation soil layer. The permeability model revealed that soil permeability significantly influenced contamination dispersion and contributed to delineate the contamination boundary accurately. The ecological hazard model targeted the high ecological hazard area and determined the high hazard contribution of Cd and Hg in the site soil. The outcomes can be directly applied to actual site remediation and provide a reference for the contaminated sites evaluation and restoration in the future.
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•Multi-source model establishes relationships between influences on site pollution.•3D visualization holds great potential for finely delineating soil pollution.•3D visualization of multi-metal composite pollution plumes was realized.
Toxic metal(loid) (TM) soil pollution at large-scale non-ferrous metal smelting contaminated sites is of great concern in China, but there are no detailed reports relating to them. A comprehensive ...study was conducted to determine contamination characteristics and horizontal and vertical spatial distribution patterns of soils at an abandoned zinc smelting site in Southern China. The spatial distribution of TMs revealed that soil environmental quality was seriously threatened, with Cd, Zn, As, Pb and Hg being the main contaminants present. The distribution of all TMs showed strong spatial heterogeneity and were expressed as a "patchy aggregation" pattern due to strong anthropogenic and production activities. Vertical migration of TMs indicated that the pollutants were mainly concentrated in the fill layers. Different contaminants had various migration depths, with migration occurring as: Cd > Hg > As > Zn > Pb> Cu> Mn> Sb. Analysis of their spatial variability showed that As, Pb, Cd and Hg had strong regional spatial variability. This research provides a new approach to comprehensively analyze TM pollution characteristics of non-ferrous smelting sites. It provides valuable information for guiding post-remediation strategies at abandoned non-ferrous metal smelting sites.
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•Multidimensional distribution pattern of TMs at smelting sites is described.•Variability of TM pollution is determined both horizontally and vertically.•TM distribution revealed "patchy aggregation" due to production activities.•TMs revealed varying migration depths, expressed as: Cd > Hg > As > Zn > Pb> Cu > Mn > Sb.
•A method to classify and quantify factors affecting site contamination is proposed.•Potential pollution source is key factor in determining the distribution of pollution.•Soil permeability is the ...dominant factor influencing the diffusion of heavy metals.
Smelting activities are the main pathway for the anthropogenic release of heavy metals (HMs) into the soil-groundwater environment. It is vital to identify the factors affecting HMs pollution to better prevent and manage soil pollution. The present study conducted a comprehensive investigation of HMs in soil from a large abandoned Zn smelting site. An integrated approach was proposed to classify and quantify the factors affecting HMs pollution in the site. Besides, the quantitative relationship between hydrogeological characteristics, pollution transmission pathways, smelting activities and HMs pollution was established. Results showed that the soils were highly contaminated by HMs with a pollution index trend of As > Zn > Cd > Pb > Hg. In identifying the pollution hotspots, we conclude that the pollution hotspots of Pb, As, Cd, and Hg present a concentrated distribution pattern. Geo-detector method results showed that the dominant driving factors for HMs distribution and accumulation were the potential pollution source and soil permeability. Additionally, the main drivers are variable for different HMs, and the interaction among factors also enhanced soil HMs contamination. Our analysis illustrates how the confounding influences from complex environmental factors can be distilled to identify key factors in pollution formation to guide future remediation strategies.
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Cantonese as a World Language Zeng, Jiaqing; Agha, Asif
Journal of student research (Houston, Tex.),
07/2021, Letnik:
10, Številka:
2
Journal Article
Recenzirano
In this paper, I will be comparing different registers of Cantonese from all around the world, mainly focusing on the Pearl River Delta region after the 1800s. Yet my larger purpose is to draw ...attention to how these different registers relate to the cultural values and social lives of the people living in those places. Max Weinreich, a pioneer sociolinguist and Yiddish scholar once said, “a language is a dialect with an army and a navy (Fishman).” Cantonese is no exception, and the state of this language has been dependent upon four factors: the geographic distribution of the Cantonese-speaking population, the economic development of Cantonese-speaking regions, official status, and international significance.
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•Predicting contaminant transport from a soil-groundwater system perspective.•To achieve the prediction of heavy metal pollution trends in the smelting site.•To implement the design ...of pollution prevention and control for the smelting site.•Expanding the application of numerical simulation in contaminated site research.
The spread of heavy metal contaminations originating from polluted industrial sites pose major environmental risks to surrounding areas. However, the migration of heavy metals in the subsurface is a very complex process that requires the coupling of geological, hydrological, solute transport and geochemical data to better understand and predict contaminant flow paths, plume movement in space and time. In this study, a three-dimensional (3D) variable saturated solute transport numerical model of soil-groundwater was developed to understand pollution risks in a large lead–zinc (Pb-Zn) smelting site. Using the calibrated numerical model, risk trends of heavy metal pollution were predicted, and the design and evaluation of a pollution control technology were proposed. The results showed that the risk of heavy metal spillover was extremely high. It could break through the geographical boundary of the site after 60 days and affect the downstream river on the 712th day. By using a permeable reactive barrier (PRB) based on zero-valent iron (ZVI) and bentonite, the time for the Cd pollution plume to reach the river could be effectively delayed by 225 days, and its diffusion range reduced to 10.2%. However, 31–42% of the contaminants continued to spread outwards through lateral flow pathways even with a PRB. Based on these results, a better remediation strategy for the smelting site is to first remove, passivate or solidify the existing pollution sources, and then use PRB technology to block the pollution transmission pathways. The research results have expanded the application of numerical simulation in the study of industrial pollution sites, providing guidance methods and technical support for pollution prevention and control and space utilization at polluted non-ferrous smelting sites.
Groundwater pollution is a recurrent problem in abandoned non-ferrous metal smelting sites, and its severity is influenced by topsoil contamination, hydrogeological characteristics, and ...hydrogeochemical conditions. In such unique areas, traditional methods for evaluating groundwater pollution risk are biased, as the long production history of these sites have led to highly polluted and heterogeneous soil and groundwater. Herein, based on a typical lead-zinc smelting site, As, Pb, Zn, Cd, Mn, and Ni were found to be the predominant heavy metal (loid)s in groundwater, with respective exceedance rates of 44.4%, 50.0%, 72.2%, 88.9%, 88.9%, and 61.1%. Combined with the groundwater pollution characteristics, the representative hydrogeochemical factors were screened out to optimize the following aquifer vulnerability evaluation using the AHP-DRASTICH method. A comprehensive evaluation model (DI-NCPI) for groundwater pollution risk was established by combining the DRASTICH index (DI) obtained after optimization and the Nemerow comprehensive contamination index (NCPI) of topsoil. The fit between DI-NCPI and groundwater heavy metal (loid) pollution index reached 0.956, which laterally confirms that the model has some reference value. In terms of distribution, the high-risk and very high-risk zones were mainly concentrated in the zinc smelting system, located in the southeastern and central-western parts of the site. These areas have relatively high levels of topsoil contamination and aquifer vulnerability and require focused attention in site remediation. This research highlights the importance of combining topsoil contamination and aquifer vulnerability to evaluate groundwater pollution risk in smelting areas. It provides a more targeted reference for groundwater remediation strategies in abandoned smelting sites, as well as severely polluted industrial areas.
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