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In the petroleum sector, the generation of oily sludge is an unavoidable byproduct, necessitating the development of efficient treatment strategies for both economic gain and the mitigation of negative environmental impacts. The intricate composition of oily sludge poses a formidable challenge, as existing treatment methodologies frequently fall short of achieving baseline disposal criteria. The processes of demulsification and dehydration are integral to diminishing the oil content and reclaiming valuable crude oil, thereby playing a critical role in the management of oily sludge. Among the myriad of treatment solutions, ultrasonic technology has emerged as a particularly effective physical method, celebrated for its diverse applications and lack of resultant secondary pollution. This comprehensive review delves into the underlying mechanisms and recent progress in the ultrasonic treatment of oily sludge, with a specific focus on its industrial implementations within China. Both isolated ultrasonic treatment and its combination with other technological approaches have proven successful in addressing oily sludge challenges. The adoption of industrial-scale systems that amalgamate ultrasound with multi-technological processes has shown marked enhancements in treatment efficacy. The fusion of ultrasonic technology with other cutting-edge methods holds considerable potential across a spectrum of applications. To fulfill the goals of resource recovery, reduction, and neutralization in oily sludge management, the industrial adoption and adept application of a variety of treatment technologies are imperative. [ABSTRACT FROM AUTHOR]

A study of two typical red soil profiles, Gumu (GM-limestone) and Sanjiacun (SJC-dolomite) was conducted at Yunnan–Guizhou Plateau, China. The study employed mineralogy, geochemical and elemental ratios to assess the mobilisation and distribution of elements during weathering and pedogenesis. The mineralogy results revealed similarity in distribution of secondary minerals in both profiles, with exception at the ferricrete layer. The results revealed inheritance relationship between red soils and their underlying bedrocks indicating that clay minerals were likely derived from in situ weathering products or metasomatic process rather than detrital process. During weathering and pedogenesis process, alkaline elements such as K and Rb behave similarly and were closely related. All lanthanide elements except for Ce shared similar transport trend with Y and Be; however, Be exhibited significant enrichment at ferricrete layer of the dolomite profile. Transitional elements such as Co and Mn behave similarly; while, the High Field Strength Elements (HFSE) were stable, except for Th and Sc which indicate depletion in upper soil layer of the dolomite profile. Our findings further revealed that both profiles have experienced intense chemical weathering with high Chemical Index of Alteration values (CIA: 83–93) and a constant Ba/Sr ratio > 2. Overall, both profiles experienced similar elemental behaviour with the accumulation of major elements, the leaching of alkaline earth elements and the fluctuation of trace elements including Rare earth elements (REEs). The elemental behaviour was primarily controlled by redox reaction, pH, water availability, ionic radii and the stability of secondary oxides/hydroxides. Our study further highlights the use of newly proposed geochemical proxy Fe/Na ratio, which revealed high correlation (R2 ≈ 0.90) with U, Ba, Zn, Cu, Mo, Ni, Sb and REEs of power functions. These findings indicate that Fe/Na ratio may be used to investigate the behaviour of trace elements including REEs in highly weathered soils. [ABSTRACT FROM AUTHOR]

Abstract Beijing experienced a period of severe atmospheric particulate pollution from 2015 to 2016. In order to acquire the characteristics of polycyclic aromatic hydrocarbons (PAHs) under heavy polluting status, one year sampling campaign was carried out. We selected PM2.5 samples which had the highest concentrations or suffered serious haze-fog weathers in each month. Through the analysis of data from heavily polluting phase, the mean concentrations of PM2.5 and PAHs in winter (369.63 μg m−3 and 223.60 ng m−3) were obviously higher than that in other seasons. The concentration of Σ 16 PAHs ranged from 3.22 to 297.01 ng m−3, with a mean value of 77.48 ng m−3. In winter, 4-ring PAH congeners (52.33%) contributed the most in PM2.5, followed by 5-rings (27.05%), 6-rings (11.55%) and 2∼3-rings (9.06%). Summertime measurements showed the highest decline in PAHs concentrations for 3∼5-ring congeners. The diagnostic ratios and PCA analysis manifest that vehicle and combustion emission were major sources and totally occupied 88.57% under heavy polluting stage. Moreover, exponential relationship between LWM/HWM (light/high weight molecule-PAHs) and combustion-derived PAHs, as well as linear relationship between BghiP and ∑PAHs verified that the pollution sources mentioned above affected local atmosphere environment as major sources. The highest total BaP equivalent concentration suggested that toxicity potency under heavy polluting phase was mainly attributed to 5-ring PAHs. Through analysis of carcinogenic-PAHs, potency risk to adults was significantly higher than that to children. BaP, BbF and DahA, which belong to 5-ring congeners, contributed the highest potency carcinogenic risk. BbF in winter, BaP in spring and winter may cause potential risk to local residents. Graphical abstract Image Highlights • Characteristics of PAHs under heavy polluting phase were studied in urban Beijing. • 4-ring PAH congeners (52.33%) contributed the most in PM2.5 in winter. • Diesel-fuelled vehicle emission and coal combustion were major sources under heavy polluting stage. • Toxicity potency was mainly influenced by 5-ring PAH congeners, such as BaP, BbF and DahA. • BbF in winter, BaP in spring and winter may cause potential risk to citizen. [ABSTRACT FROM AUTHOR]

The isotope ratios of Sr are useful tracers for studying parent material sources, weathering processes, and biogeochemical cycling. Mineralogical and geochemical investigations of two lateritic weathering covers, in an area close to the Tropic of Cancer (Guangxi Province, southern China), were undertaken to study the regional weathering processes and Sr isotopic sources. We found that weathering and decomposition of Rb- and Sr-bearing minerals change the Sr isotopic composition in weathering products (lateritic soils). Weathering of illite lowered the 87Sr/86Sr ratio whereas dissolving and leaching of carbonate minerals increased the 87Sr/86Sr ratio. An Fe nodular horizon is widely developed on the top of the weathering covers in the studied area and it differs from the lateritic soil horizon in mineral composition, construction, and elemental concentration. Furthermore, both Fe2O3 and P2O5 (concentrations) are negatively correlated with the 87Sr/86Sr ratios, suggesting fixation of apatite by Fe oxides is a controlling factor of the Sr isotopic composition in the Fe nodular horizon. The 87Sr/86Sr and Nb/Sr ratios imply the contents and proportions of Fe nodules and clay are critical in controlling the changes of Sr isotopic composition in the Fe nodular horizon. The two stages of the weathering process of carbonate rocks are revealed by the87Sr/86Sr versus Nb/Sr diagram. The 87Sr/86Sr and Rb/Sr ratios suggest that Sr isotopes in the weathering covers within the studied area are derived mainly from parent rock weathering and that the contributions from allothogenic Sr isotopes are limited. A comparison of Sr isotopic composition signatures in the weathering covers of the studied area and Guizhou Province provided insight into the Sr isotopic source and paleogeographic evolution of southern China. From the Permian to the Triassic, the continental fragment sources of the South China sedimentary basin changed significantly. In the Permian, Southern China presented the paleogeographic pattern that the north was higher (in elevation) than the south. [ABSTRACT FROM AUTHOR]

Electronic waste (e-waste) dismantling is a significant source of atmospheric pollutants, including volatile organic compounds (VOCs) and heavy metals (HMs), which may have adverse effects on the surrounding environment and residents. However, the organized emission inventories and emission characteristics of VOCs and HMs from e-waste dismantling are not well documented. In this study, the concentrations and components of VOCs and HMs were monitored at the exhaust gas treatment facility from two process areas of a typical e-waste dismantling park in southern China in 2021. Emission inventories of VOCs and HMs were established, with total emissions of 8.85 t/a and 18.3 kg/a for VOCs and HMs in this park, respectively. The cutting & crushing (CC) area was the largest emissions source, accounting for 82.6% of VOCs and 79.9% of HMs, respectively, while the baking plate (BP) area had higher emission factors. Additionally, the concentration and composition of VOCs and HMs in the park were also analyzed. For VOCs, the concentrations of halogenated hydrocarbons and aromatic hydrocarbons were comparable in the park, while m/p-xylene, o-xylene, and chlorobenzene were the key VOC species. The HM concentrations followed the order of Pb > Cu > Mn > Ni > As > Cd > Hg, with Pb and Cu being the main heavy metals released. This is the first VOC and HM emission inventory for the e-waste dismantling park, and our data will lay a solid ground for pollution control and management for the e-waste dismantling industry. [Display omitted] • VOCs and HMs emission inventories of an e-waste dismantling park were established. • The VOCs and HMs emissions were 8.85 t/a and 18.3 kg/a, respectively. • The emission factors of VOCs and HMs were 25.7 g/t and 65.7 mg/t, respectively. • The CC area was the main emission source and the BP area had higher emission factors. • Xylene and chlorobenzene, Pb and Cu were the key VOCs or HMs pollutants in the park. [ABSTRACT FROM AUTHOR]

The characterization of the concentration and chemical speciation of heavy metals in surface and vertical profile soils is a necessary for pollution monitoring and the potential risk assessment of the heavy metals (HMs) to animal and human health. Surface soil samples (n = 14) and vertical profile soil samples (n = 36) from selected sites (n = 6) were collected from coal-mine brownfield in the Qingshui River Basin, in which the concentrations and chemical speciation of HMs (Cd, Cr, Cu, Mn, Ni, Pb, Zn) in surface soils and HM concentrations in vertical profile soils were determined by ICP-OES and analyzed using methods of geo-accumulation index (I geo ), Tucker 3 model and health risk assessment. The chemical fractions of HMs were extracted by BCR-sequential extraction procedure. Results show that HMs in surface soils accumulate in descending order of Cd > Pb > Cu > Ni > Mn > Zn > Cr. All HMs are associated with residue fraction to different degrees. Manganese and Ni are closely related to extractable BCR fractions and turn to be the severer pollutants in some sites. The I geo values of HMs in vertical profile soils indicate ‘uncontaminated’. Whereas coal mining activities with long history increase HM concentrations in subsurface soils at the coal mine former site. The non-carcinogenic risk posed by HM extractable fractions to children and adults fall below the safe level of 1. Lead extractable fraction exhibits the highest risk value in the case of children. The levels of carcinogenic risk posed by Cr and Ni extractable fractions are above that of the United States Environmental Protection Agency (USEPA) acceptable level (1 × 10 − 6 ). Nickel extractable fraction exhibits the highest carcinogenic risk values for children with exceeding that of the maximum USEPA acceptable level (1 × 10 − 4 ). [ABSTRACT FROM AUTHOR]

Mining and smelting areas in Hezhang have generated a large amount of heavy metals into the environment. For that cause, an evaluative study on human exposure to heavy metals including Co, Ni, Cu, Zn, Cr, As, Cd, Pb, Sb, Bi, Be, and Hg in hair and urine was conducted for their concentrations and correlations. Daily exposure and non-carcinogenic and carcinogenic risk were estimated. Sixty-eight scalp hair and 66 urine samples were taken from participants of different ages (6-17, 18-40, 41-60, and ≥ 65 years) living in the vicinity of an agricultural soil near mine and smelting areas. The results compared to the earlier studies showed an elevated concentration of Pb, Be, Bi, Co, Cr, Ni, Sb, and Zn in hair and urine. These heavy metals were more elevated in mining than in smelting. Considering gender differences, females were likely to be more affected than male. By investigating age differences in this area, high heavy metal concentrations in male's hair and urine existed in age of 18-40 and ≥ 66, respectively. However, females did not present homogeneous age distribution. Hair and urine showed a different distribution of heavy metals in different age and gender. In some cases, significant correlation was found between heavy metals in hair and urine ( P > 0.05 and P > 0.01) in mining area. The estimated average daily intake of heavy metals in vegetables showed a great contribution compared to the soil and water. Non-carcinogenic and carcinogenic risk values of total pathways in mining and smelting areas were higher than 1 and exceeded the acceptable levels. Thus, the obtained data might be useful for further studies. They can serve as a basis of comparison and assessing the effect of simultaneous exposure from heavy metals in mining and smelting areas, and potential health risks from exposure to heavy metals in vegetables need more consideration. [ABSTRACT FROM AUTHOR]

Total arsenic (As) in suspended particulate matter (SPM) of lacustrine ecosystems has been extensively documented, but knowledge on the distribution of As between the particle and aqueous phases in freshwater lakes remains largely unknown. The present study employed a rapid method to determine the total and dissolved As and As in SPM at sites covering the entire areas of three large shallow lakes in China, e.g., Taihu, Chaohu, and Dianchi, to obtain a 'representative' mean value of the As concentration in various phases. The average concentrations of total and dissolved As were below 6.0 and 3.3 μg/L, respectively. Arsenic in SPM was much higher than that in waters, as ranging from 24.7 to 516 μg/g. Lake Taihu exhibited extensive seasonal variation both in total and dissolved As, while little difference was observed in SPM concentration, with an average value of 54.2 and 49.3 mg/L in winter and summer, respectively. Among the algae in the three lakes, Cyanophyta dominated in both cell abundance and biomass. Algae mass occupied significant parts of SPM, especially in Dianchi; the proportions of algae in the SPM fractions were measured as 10.4 and 7.1 % in Taihu in winter and summer, 4.5 % in Chaohu, and 53.3 % in Dianchi, both in summer season. The total As in SPM had a significant positive relationship with total As in water and a high distribution coefficient (Kd) between SPM and dissolved fraction of As at all three lakes. The high proportions of Algae, especially Cyanophyta in the composition of SPM in the three large shallow lakes, might play an important role in affecting the As distribution between the aqueous and particulate phases in aquatic ecosystem. [ABSTRACT FROM AUTHOR]

Mining has been carried out upstream of Miyun Reservoir, Beijing, for several decades, and has caused metal emissions to the environment, threatening human health. We conducted a soil survey to assess metal contamination in this area and to determine distribution of heavy metals in the particle size. We attempted to determine the possible sources of the metals and the significance of metals in the fine particle fractions to soil risk assessments. Thirty-four soil samples were collected, and eight samples were partitioned into seven size fractions. Most of the metal concentrations in the soils were higher than the background levels in Beijing, and the metal concentrations and total organic matter (TOC) contents generally increased as the particle size decreased. Each metal except Hg significantly positively correlated with the TOC. The metals in the coarse-grained soils were mainly derived from parent materials, but the metals in the fine fractions were mostly anthropogenic. Statistical analyses showed that there were three metal sources: Cd, Cu, Hg, Pb, and Zn had anthropogenic sources; Co, Cr, Ni, and V had mixed anthropogenic and natural sources; and As and Be had natural sources. The trace metals were primarily in the clay and fine silt fractions, and they might pose health risks through the inhalation of resuspended soil particles (PM10 and PM2.5). The elevated accumulation factors, enrichment factors, and ecological risk indices for the metals in the fine fractions suggest that risk assessments should be based on the fine particle size. [ABSTRACT FROM AUTHOR]

Abstract: In this study, geologic field observations and geochemical indicators of the types of representative bauxite deposits, terra rossa and underlying carbonate rocks in western Guangxi, southern China, were investigated. Their interrelations, material sources, formation and evolution processes were discussed. The results show an inherited relationship between terra rossa and its underlying limestone. The relevant parameter diagrams of trace and rare earth elements suggest that the two types of bauxite deposits probably possess identical material sources. Both bauxite deposits and terra rossa have close affinities with each other, implying that carbonate rocks similar to the underlying limestone might be a major material source for their formation. However, the eolian component represented by Chinese loess and igneous rock genesis with respect to Emeishan basalt plume may not contribute so much to the material source of bauxite deposits and terra rossa. In the process of leaching and pedogenesis, the mobile elements, such as Ca, Mg and Na, were preferentially dissolved and removed from parent rocks, and the less mobile elements Al, Fe, Ti and Si were accumulated and enriched. During the period of diagenesis and bauxitization, elements K and Si were largely removed from the system. Especially, in transformation from primary bauxite to secondary bauxite deposit, the contents of many “less mobile” elements, such as Fe and Ti, decreased. This finding is possibly due to the strongly acidic environment caused by decomposition of pyrite in primary sedimentation-type bauxite deposit. This study systematically analyzed the inherited relations and evolution processes among carbonate rock, terra rossa, and two types of bauxite deposits, and gave a guide for the bauxite deposit prospecting in western Guangxi. [Copyright &y& Elsevier]

In order to investigate the metal distribution, speciation, correlation and origin, risk assessment, 86 surface soil samples from the catchment area around the Miyun Reservoir, Beijing, including samples from gold and iron mine areas, were monitored for fractions of heavy metal and total contents. Most of the metal concentrations in the gold and iron mine soil samples exceeded the metal background levels in Beijing. The contents of most elements in the gold mine tailings were noticeably higher than those in the iron mine tailings. Geochemical speciation data of the metals showed that the residual fraction dominated most of the heavy metals in both mines. In both mine areas, Mn had the greatest the acid-soluble fraction (F1) per portion. The high secondary-phase fraction portion of Cd in gold mine samples indicated that there was a direct potential hazard to organisms in the tested areas. Multivariate analysis coupled with the contents of selected metals, showed that Hg, Pb, Cr, and Ni in gold mine areas represented anthropogenic sources; Cd, Pb, and Cr in iron mine areas represented industrial sources. There was moderate to high contamination of a few metals in the gold and iron soil samples, the contamination levels were relatively higher in gold mine than in iron mine soils. [ABSTRACT FROM AUTHOR]

Heavy metals concentrations in surface sediments from Miyun Reservoir were determined to evaluate the pollution and identify the sources. The average content of metals in sediments from Miyun Reservoir followed the order Al>Fe>Ti>Mn>V>Zn>Cr>Ni>Cu>Pb>As>Cd>Hg, and the most mean values were lower than the globe average shale. Heavy metals concentrations at the inflow area of Baihe were higher than those at the inflow area of Chaohe. Heavy metals pollution assessment was carried out by factor enrichment (EF), geoaccumulation index ( I), and potential ecological risk (RI). The EF values for all heavy metals except Hg, Cd, and Cr at several sites were lower than 3, suggesting low anthropogenic impact on the metals level. The I values of Pb indicated that half of the sites were unpolluted to moderately polluted and mainly located in the Baihe area of the reservoir. The RI showed that heavy metals of Miyun Reservoir were low potential risk, however, Hg approached or belonged to moderate ecological risk at sites of M5, M7, and M13. Correlation analysis and principal component suggested that Ni, Cu, V, Zn, Mn, Cr, Ti, and Pb were derived from soil erosion in upper reaches of the reservoir, while Fe, Cd, Hg, As, and partial Pb originated from anthropogenic sources, particularly industrial mining and gold tailings. [ABSTRACT FROM AUTHOR]

The carbon and nitrogen isotopes in the surface sediments, plants, and soil in the upper reaches of the Chaobai River have been researched. The results showed −27.75‰ - −21.58‰ and 1.32‰-6.74‰ for carbon and nitrogen isotopic ratios in the surface sediments, respectively. The sources of sedimentary organic matter in this area are soil organic matter, aquatic vascular plants, and riverine plankton, respectively, and a significant contributor to sediment in the Chaohe River, the Baihe River, and the Miyun Reservoir areas is soil organic matter. Furthermore, part of sedimentary organic matter in the Miyun Reservoir is attributed to the input from the Chaohe River and the Baihe River, the other is from C4 vegetation growing around individual point stations at the Miyun Reservoir. Compared with the situation in Hebei Province, the contribution of soil organic matter decreased significantly and river plankton and aquatic vascular plants increased significantly in Beijing municipal areas. This study reveals that the source of organic matter has a close relationship with the soil erosion. [ABSTRACT FROM AUTHOR]

Abstract: We analyzed dissolved major elements, δ13CDIC and δ34SSO4 in river waters from a karstic and a granitic terrain to examine weathering processes and the influence of basin geology on water quality and associated riverine alkalinity transport. Results show that waters from the karstic terrain have higher total dissolved solids (TDS), major ion concentrations and δ13CDIC values but lower K+, Na+ and Si concentration and δ34SSO4 values than that from the granitic terrain. The compositions of major ions and isotopes indicate that the solutes of the granitic terrain are controlled by processes of silicate and carbonate dissolution by carbonic acid. However, carbonate dissolution by both carbonic and sulfuric acid are dominant processes in karstic terrain. Total erosion rates, dissolved inorganic carbon (DIC) flux and CO2 uptake were 28.0tkm−2 yr−1, 2.9×105 molkm−2 yr−1 and 2.3×105 molkm−2 yr−1 for the granitic terrain and 70.2tkm−2 yr−1, 11.9×105 molkm−2 yr−1 and 6.4×105 molkm−2 yr−1 for the karstic terrain, respectively. These results indicated the karstic area plays an important role in uptake of CO2 and DIC flux along the Yangzte River Basin. Our results also revealed that CO2 uptake due to carbonate chemical weathering in both karstic and granitic terrain is very high and provide as much or more DIC flux than that from silicate chemical weathering. [Copyright &y& Elsevier]

Abstract: The watershed in the southern Jiangxi Province (Jiangxi Province is called simply Gan) (SGW) and the watershed in the central Guizhou Province (Guizhou Province is called simply Qian) (CQW) are two subtropical watersheds of the Yangtze River in China. Both watersheds have similar latitudes and climate, but distinct differences in basin lithology. These similarities and differences provide a good natural laboratory in which to investigate weathering processes and Sr end-members in river waters. This work aims to identify and contrast the sources, fluxes and controls on Sr isotopic composition in the river waters of these two areas. Results showed that the 87Sr/86Sr in the SGW waters ranged from 0.716501 to 0.724931, with dissolved Sr averaging 27μgl−1. Rhyolites and granites are two major sources for the dissolved Sr. The SGW waters receive 42% of their Sr from silicates weathering, 32% from carbonates and 3.2% from evaporites. 87Sr/86Sr in the CQW waters has a lesser variation from 0.707694 to 0.710039, but higher Sr contents (average of 208μgl−1). Dolomite, limestone and dolomitic limestone are major sources of Sr in the waters. The CQW waters receive 69% of their Sr from carbonates, 1.7% from silicates and 0.9% from evaporites. The chemical erosion rate and Sr flux in the CQW are 122tkm−2 a−1 and 0.079tkm−2 a−1, respectively, which are higher than those of the SGW (56tkm−2 a−1 and 0.021tkm−2 a−1, respectively). These data suggest that the intensive carbonates weathering occurred in the karstic area in the upper-reach of the Yangtze River exert great influence on the high Sr concentration and low Sr isotopic ratios in the River. [Copyright &y& Elsevier]

Rivers in metropolitan areas are often highly polluted with materials that pose a threat to a large number of residents. Human influences lead to contaminants in metropolitan rivers having more complex sources than those in rural rivers. This complexity results in contamination that is unstable and rapidly changing. Here, the contents and chemical fractionation patterns of eleven toxic elements (As, Cd, Co, Cu, Cr, Mn, Ni, Pb, Zn, Y, and Hg) were evaluated in 13 samples collected from along the Beiyunhe River in Beijing, China. The results revealed that the metal contents were unevenly distributed along the river, with higher levels being observed in the downriver sites and the rendezvous sites. Additionally, more than 80% of the metals were found to be in the residual phase. The organic and sulfide phases were the most important extractable phases of most metals, with Ni, Co, Cu, and Cr primarily being associated with these phases and As, Cd, and Zn having a strong association with the iron/manganese oxide and hydroxide phases. Additionally, Mn was associated with the exchangeable and carbonate phases, with the lowest concentrations being observed in the organic and sulfide phases. Conversely, the metal exchangeable and carbonate phases were uniformly distributed throughout the river. Analysis of the metal sources revealed that particles input from the atmosphere comprised a considerable amount of the metals in the Beiyunhe River. However, these metals likely do not enter the sediment via atmospheric deposition directly, but rather through rainwater runoff into the river. The methods used in the present study will be useful in other studies that require analysis of complex data. [ABSTRACT FROM AUTHOR]

• Soil profiles indicate clear inheritance from the underlying bedrock. • Heavier isotopes of δ30Si and δ7Li increased with changed in landform. • The weathering is different impacted by biological and physicochemical processes. • Si and Li isotopic systems are useful for origin and evolution of complex soils. Silicon and lithium isotopes are increasingly used to trace current and past weathering processes. Herein, four soil profiles (SL1, SL2, XNC, and DP) in the karst critical zone in southwest China were studied. The bedrock of the SL1, SL2, and XNC profiles are limestone, while the bedrock of the DP profile is shale. By analyzing their major elements, trace elements, and mineral compositions as well as using Si and Li isotope methods, we were able to identify the material source of the laterite in southwest China and study its element behavior and isotope fractionation characteristics during the weathering process. The results show that the δ30Si of the profiles overlying limestone (SL1, SL2, and XNC) range from −0.5‰ to 0.7‰, and those of the δ7Li range from 0.28‰ to 3.54‰, while the profile overlying shale (DP) has a large range of δ30Si variation (from −1.2‰ to 1.1‰). The results reveal a clear inheritance from the underlying bedrock, indicating that the profiles reflect in-situ weathering. Although no obvious relationship exists among the chemical index of alteration (CIA), the δ30Si, and the δ7Li, a significant correlation between δ30Si and δ7Li indicates that the isotope fractionation of the studied profiles is mainly affected by the dissolution and formation of minerals during the weathering process, and the biological effect is relatively small. Further, a diagram of Li/Al versus δ7Li shows a decrease in both Li/Al and δ7Li during weathering. [ABSTRACT FROM AUTHOR]

The chemical compositions and soil erosion characteristics of three soil profiles along a hillslope in karst area, southwest China were investigated. The material sources, element behavior and relationship between soil erosion and soil formation are discussed. Based on the 137Cs technique, the mean soil redistribution rates were found to be 11.88, −15.31 and −21.03 t ha−1 year−1 in the summit (DSD), shoulder (DSY) and toeslope (DSJ) profiles, respectively. The results show that the three profile soils are in situ weathering products of the underlying bedrocks and have inherited relationships. The Al, rare earth elements (REEs) and high field strength elements (HFSEs) contents increase with increasing clay content in DSY and DSJ profiles, indicating that these elements could be loss with clay particles via soil erosion. Coarse particles contained Si accumulates at the DSJ profile due to the migration of soil from upslope, resulting in Si enrichment. The REEs and HFSEs are mainly transported from the deposition profile DSD as solutes by chemical weathering and from the erosion profiles DSY and DSJ as particles by physical migration. The DSY profile has the thinnest soil layer and lowest clay contents, which facilitate the chemical reaction between minerals and soil water. Above all, we believe that at some intermediate soil erosion rate, that soils with the least input of fresh materials could experience the strongest chemical weathering, resulting in vast dissolution of minerals such as feldspar. These results suggested that soil texture, topographical features and vegetation coverage together affect the soil chemical weathering, physical erosion and element behaviors in karst hillslope. Unlabelled Image • Human activities can significantly accelerate soil erosion of the karst hillslopes. • Soil texture affects the behaviors and redistribution of soil elements. • Topographical features influence the soil provenance in small regions. • Deposition area loses REEs and HFSEs mainly due to chemical leaching. • Soils without input of fresh materials experience strong chemical weathering. [ABSTRACT FROM AUTHOR]

Soil erosion is a global environmental issue that can lead to the loss of nutrient-rich topsoil and even soil desertification, which is more severe in vulnerable and sensitive karst areas. Currently, it is imperative to explore the soil erosion mechanism and the weathering process to help prevent soil degradation in the karst area. In this study, we estimated the soil erosion rate of a representative karst slope in Shilin area of China by 137Cs tracer method. We also analyzed the changes of soil total organic carbon (TOC), total nitrogen (TN), and total phosphorus (TP) along the soil profiles. The results show that there is mild to moderate intensity erosion in this area, and erosion rates in different locations of slope are in the following order: hilltop > hillside > bottom. The 137Cs content has a certain correlation with TOC, TN and TP content in the soil profile, which indicates they may have similar loss pathways. Furthermore, the chemical index of alteration (CIA), Na/K value and their relation with soil erosion are analyzed and reveal that the studied area is seriously affected by physical erosion and chemical weathering under a hot and humid environment area. [ABSTRACT FROM AUTHOR]

Beijing, as the capital of China, is one of the most populous cities in the world. With the fine particulate matter pollution being increasingly serious, daily exposure to hazardous ingredients caused more and more attention. Current research concerning risk evaluation in Beijing was relative less. In November, 2013, samples were collected in seven different functional areas of Beijing, so as to better understand the risk to human health caused by particle matter pollution in this region. PM2.5 pollution in rural and urban Beijing was relative high under haze–fog days in comparison with non haze–fog value. Zn and Ba showed the highest concentration levels among non-carcinogenic metals. The non-carcinogenic metal concentration at all the sites ranged in the same order: Ce, Pb, Cu, V and Sb. Higher ring PAHs (with four to six rings) were the dominant species and constituted more than 90% of the Σ 14 PAHs. Pb (4.34 × 10 − 4 for men, 3.73 × 10 − 4 for women) presented the maximum risk level for non-carcinogenic heavy metals in the whole study area. While, risk levels of Cr at residential areas, schools, Olympic Park and rural countryside exceeded the limit for adults. In haze–fog days, the carcinogenic PAH risk level in each functional area ranged in the order: rural countryside > inner suburban district > Olympic Park > city central > schools > ecological reserve > residential areas. To some extent, benzo(a)pyrene may had a potential risk to adults, and other carcinogenic PAHs were all under average risk acceptance. [ABSTRACT FROM AUTHOR]

Bacteria within a metacommunity could be partitioned into different subcommunities ecological assemblages in light of potential importance for the community function. It is unknown how abundant and rare microbial subcommunities in urban river sediments respond to heavy metal pollutants. Using high-throughput sequencing, we analyzed these response patterns in the heavliy polluted (Beijing, China). We found that this river faces substantial ecological risks, owing to high rates of Cd and Hg pollution from urban activities. Surprisingly, abundant and rare subcommunity structures showed opposite responses to heavy metals. Abundant taxa, such as Crenarchaeota and Euryarchaeota, are resistant to heavy metal pollution through the synergistic of ammonia nitrogen (NH 4 + -N) and total phosphorus (TP). By contrast, rare taxa, such as Verrucomicrobia, Fibrobacteres, Berkelbacteria, and Euryarchaeota, had a high synergy with NH 4 + -N and TP with high a resilience to heavy metal pollution. However, the functions of both abundant and rare subcommunities showed a similar response to heavy metal pollutants, especially in denitrification processes. The abundant taxa responded to heavy metal pollution through methanogenesis by CO 2 reduction with H 2 , human pathogens nosocomia, sulfate respiration, photoheterotrophy, and dark sulfide oxidation synergy with NH 4 + -N and TP. The rare taxa responded to heavy metals through methanogenesis by CO 2 reduction with H 2 , cellulolysis, sulfate respiration, intracellular parasites, nitrate reduction and plant pathogen. We observed distinct patterns between the structural and functional responses of microbial subcommunities to heavy metal pollutants. Our findings support the concept that denitrification processes are sensitive to but not inhibited by high levels of heavy metals pollution. We propose that the structures and functions of the abundant and rare microbial subcommunities could inform the management of pollutants in heavily polluted urban river ecosystems at fine geographical scales., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Pb pollution in soils and sediments has adverse effects on human health and the environment. Identifying and quantifying the relative contribution of Pb pollution sources are key issues to control Pb pollution. In this study, U, Th and Pb concentration, Pb enrichment coefficient and Pb isotopic composition in the sediment and surface soil samples of the Miyun Reservoir and its upstream Chaohe, Baihe and Tanghe River were analysed to determine the source and relative contribution of Pb pollution. Results show a significant enrichment of Pb in the sediments of the Baihe River (2.7 ± 0.9). The enrichment of Pb in the soils in Baihe (8.0 ± 10.5) and Tanghe (313.3 ± 1139.4) is more obvious, and Pb is unevenly distributed in the soil in the Tanghe Basin. In general, soil is more seriously affected by human activities than sediment. The Pb isotope ratio indicates that mining activities and natural background are the main sources of Pb in soil and sediment. Based on the binary mixture model, the average contribution rate of mining activities to Pb pollution in the sediment is 21.5%, of which the contribution rates in the Miyun Reservoir, Chaohe, Baihe and Tanghe River are 14.86%, 17.20%, 41.03% and 26.32%, respectively. The average contribution rate of mining activities to soil Pb is 43.1%, among which the contribution rates in the Chaohe River Basin, Baihe River Basin and Tanghe River Basin are 58.79%, 60.98% and 36.24%, respectively. In summary, soils and sediments in the basin are affected by mining activities to varying degrees. Nevertheless, natural background is still the main source of Pb in the sediments in the basin and in soil in the Tanghe River. Mining activities are the main sources of Pb in soils in the Chaohe and Baihe River., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

To better understand the impacts of non-carbonic acid (NCAs, including sulfuric, nitric and organic acids) stress on DIC generation during chemical weathering, this study investigated the water chemistry and stable isotope composition ( δ 13 ) from a granitic-hosted watershed at Huangshan UNESCO Global Geopark, China. The results show that the dissolved loads of the watershed are dominated by both silicate and carbonate weathering. As a region with greatly distributed acid soil and high occurrence of acid rain, the evolution of the dissolved loads and DIC ) from a granitic-hosted watershed at Huangshan UNESCO Global Geopark, China. The results show that the dissolved loads of the watershed are dominated by both silicate and carbonate weathering. As a region with greatly distributed acid soil and high occurrence of acid rain, the evolution of the dissolved loads and δ 13 C DIC show that DIC generation in carbonate dissolution is promoted by H 2 SO 4 , reduced by HNO 3 and little disturbed by organic acids. The reduction is due to CO 2 release in carbonate weathering by strong nitric acid formed by nitrification in acid soil. New participating proportions of NCAs in rock weathering yielded by the multiple linear regressions between major ions, DIC and δ 13 C DIC are introduced into calculations of DIC yields. The overestimated DIC yields by silicate and carbonate weathering by NCAs account for about 34% of total DIC yields calculated with the assumption that all carbonates and silicates are dissolved by H 2 CO 3 alone during a year. The results imply that the modifications of DIC generation by NCAs, especially HNO 3 formed in acidic silicate soil, could consequently partly counterbalance the natural CO 2 sink in the granitic-host region.

Lead (Pb) isotopes have been widely used to identify and quantify Pb contamination in the environment. Here, the Pb isotopes, as well as the current contamination levels of Cu, Pb, Zn, Cr, Ni, Cd, As, and Hg, were investigated in soil and sediment from the historical gold mining area upstream of Miyun Reservoir, Beijing, China. The sediment had higher 206 Pb/ 207 Pb ratios (1.137 ± 0.0111) than unpolluted soil did (1.167 ± 0.0029), while the soil samples inside the mining area were much more variable (1.121 ± 0.0175). The mean concentrations (soil/sediment in mg·kg -1 ) of Pb (2470/42.5), Zn (181/113), Cu (199/36.7), Cr (117/68.8), Ni (40.4/28.9), Cd (0.791/0.336), As (8.52/5.10), and Hg (0.168/0.000343) characterized the soil/sediment of the studied area with mean I geo values of the potentially toxic element (PTE) ranging from -4.71 to 9.59 for soil and from -3.39 to 2.43 for sediment. Meanwhile, principal component analysis (PCA) and hierarchical cluster analysis (HCA) coupled with Pearson's correlation coefficient among PTEs indicated that the major source of the Cu, Zn, Pb, and Cd contamination was likely the mining activities. Evidence from Pb isotopic fingerprinting and a binary mixing model further confirmed that Pb contamination in soil and sediment came from mixed sources that are dominated by mining activity. These results highlight the persistence of PTE contamination in the historical mining site and the usefulness of Pb isotopes combined with multivariate statistical analysis to quantify contamination from mining activities.

A novel quantitative model of the relationship between diffused concentration changes and erosion rates using assessment of soil losses was developed. It derived from the analysis of surface soil (137)Cs flux variation under persistent erosion effect and based on the principle of geochemistry kinetics moving boundary. The new moving boundary model improves the basic simplified transport model (Zhang et al., 2008), and mainly applies to uniform rainfall areas which show a long-time soil erosion. The simulation results for this kind of erosion show under a long-time soil erosion, the influence of (137)Cs concentration will decrease exponentially with increasing depth. Using the new model fit to the measured (137)Cs depth distribution data in Zunyi site, Guizhou Province, China which has typical uniform rainfall provided a good fit with R(2) = 0.92. To compare the soil erosion rates calculated by the simple transport model and the new model, we take the Kaixian reference profile as example. The soil losses estimated by the previous simplified transport model are greater than those estimated by the new moving boundary model, which is consistent with our expectations., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Dual isotopes of nitrate ((15)N and (18)O) and carbon isotopes of dissolved inorganic carbon ((13)C) together with water chemistry were used to identify the sources and fate of nitrate in the upper stream of Chaobai River, north China. The results show that NO3(-) concentrations ranges from 0.03 mmol L(-1) to 0.80 mmol L(-1). Sampling sites from watershed with dominant forest land had higher NO3(-) concentrations and lower δ(15)N-NO3(-) (<10‰) in the wet season than in the dry season, while those from watershed with more anthropogenic activities had lower NO3(-) concentrations and higher δ(15)N-NO3(-) (>10‰) in the wet season. Compositions of isotopes and chemistry indicated that NO3(-) originated mainly from soil N, sewage and livestock wastes and atmospheric nitrogen. Furthermore, the mixing model suggested that soil N was the major NO3(-) source in the wet season, while the sewage and livestock wastes contributed the most in the dry season. Compared to rivers, the Miyun Reservoir had a higher contribution of atmospheric N and the N input from the upper rivers exerted significant influence over the reservoir. Mineralization and nitrification played an important role in N biogeochemistry based on the isotopes ((15)N and (18)O and (13)C) and chemical data. There appeared to be no significant denitrification in the watershed according to the three isotopes and chemical ions. The combined use of (15)N, (18)O and (13)C proved to be useful for further identification of the sources and fate of nitrate in watersheds with dominant forest land in the wet season.