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Adsorption of heavy metals on stream sediments has important implications for the fate and transport of contaminants in subsurface ecosystems. Lead (Pb) is a potentially hazardous heavy metal that is found in high amounts in anthropogenic environments, especially aquatic ecosystems. The key mechanisms for distributing this metal in the environment are adsorption and desorption in stream to sediment, and vice versa. Therefore, this work is mainly focused on the study of the influence of amorphous Fe/Al-oxyhydroxides and soil organic matter (SOM) on the adsorption of Pb onto natural stream sediment. Spiking adsorption experiments were carried out with four types of samples namely, untreated dried sediment, Fe/Al-oxyhydroxides depleted sediment, SOM depleted sediment and both Fe/Al as well as SOM depleted sediment in the pH range of 3.0 to 8.0. The results showed that Pb adsorption was reduced by up to 45% in amorphous Fe/Al-oxyhydroxide depleted sediment at pH 4.0 to 6.0, whereas a similar adsorption reduction was observed in SOM depleted sediment at pH 6.5 to 7.5. Maximum Pb adsorption was reduced by up to 75% in both amorphous Fe/Al-oxyhydroxides and SOM depleted sediment samples at pH ranges ranging from 3.0 to 7.0. Furthermore, it was shown that SOM was most significant at pH 6.5, while Fe/Al-oxyhydroxides were more important when pH was > 6.5 for the Pb adsorption in natural stream sediment. [ABSTRACT FROM AUTHOR]

The Ailaoshan Orogen in the southeastern Tibet Plateau, situated between the Yangtze and Simao blocks, underwent a complex structural, magmatic, and metamorphic evolution resulting in different tectonic subzones with varying structural lineaments and elemental concentrations. These elements can conceal or reduce anomalies due to the mutual effect between different anomaly areas. Dividing the whole zone into subzones based on tectonic settings, ore cluster areas, or sample catchment basins (Scb), geochemical and structural anomalies associated with gold (Au) mineralization have been identified utilizing mean plus twice standard deviations (Mean + 2STD), factor analysis (FA), concentration‐area (C‐A) modeling of stream sediment geochemical data, and lineament density in both the Ailaoshan Orogen and the individual subzones. The FA in the divided 98 Scbs with 6 Scbs containing Au deposits can roughly ascertain unknown rock types, identify specific element associations of known rocks and discern the porphyry or skarn‐type Au mineralization. Compared with methods of Mean + 2STD and C‐A model of data in the whole orogen, which mistake the anomalies as background or act the background as anomalies, the combined methods of FA and C‐A in the separate subzones or Scbs works well in regional metallogenic potential analysis. Mapping of lineament densities with a 10‐km circle diameter is not suitable to locate Au deposits because of the delineated large areas of medium‐high lineament density. In contrast, the use of circle diameters of 1.3 km or 1.7 km in the ore cluster scale delineates areas with a higher concentration of lineament density, consistent with the locations of known Au deposits. By analyzing the map of faults and Au anomalies, two potential prospecting targets, Scbs 1 and 63 with a sandstone as a potential host rock for Au, have been identified in the Ailaoshan Orogen. The use of combined methods in the divided subzones proved to be more effective in improving geological understanding and identifying mineralization anomalies associated with Au, rather than analyzing the entire large area. [ABSTRACT FROM AUTHOR]

Copyright of Geology & Resources is the property of Geology & Resources Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Chinese Journal of Inorganic Analytical Chemistry / Zhongguo Wuji Fenxi Huaxue is the property of Beijing Research Institute of Mining & Metallurgy Technology Group and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Exploration success relies heavily on the data obtained, but, significantly on the type of analytical methods deployed and the interpretation reached. A poorly analyzed data may obscure the true reflectivity of the data, and thus, compromised the decision made. A combined data processing approach of descriptive statistics, enrichment-depletion data normalization, geospatial elemental distribution, and stacked overlayed comparison of elements have been used in this study. The prime purpose was to demonstrate potential elemental anomalies, and predict areas of higher degree of confidence for subsequent exploration and mineral resource evaluation. One-hundred and sixty-six stream sediment samples from the Dodoma Region of the Tanzania Craton have been examined; to reveal potential elements or mineral commodity that warrant further exploration. Forty-three elements of target were examined, as this craton is globally known for its rich earth mineral commodity. Our result indicates an enrichment of transition metals (TMs) (Cu, Ni, Co, Cr, Mn and Zn), High Field Strength Elements (Y, Th, U, Zr, Nb, Hf, Ta and Pb), Large Ion Lithophile Elements (Ba and Rb) and Rare-Earth Elements (La and Ce), Platinum Group Element (Pd and Pt) and other metals (Au, As, Bi, W, Mo and Li).Obtained results point to a likely poly-metallic sources and processes; as the underlain geology is marked largely by pegmatite and migmatites, and moderate proportion of fine clastic sedimentary rocks, and minor volcanic rocks mostly to the northern domain. Theoretically, the Large Ion Lithophile Elements (LILEs), Rare-Earth Elements (REEs) and Platinum Group Elements (PGEs) are associated with felsic rocks or variable stages of plutonic granitization. Although, the TMs are often associated with mafic-ultramafic rocks, the linkage of such metals with organic-rich shales been reported elsewhere. These rocks may equally contribute to the occurrence of other metals as stated in this paper. Its intriguing to note a strong positive correlation of Li with TMs, possibility of Li control by mafic minerals in pegmatite bodies. This work proposes a polymetallic enrichment controlled by the area geology. To suggest an alluvial mining potential of the above elements in the area, resource evaluation is a requirement. The geospatial maps reveal areas worth focusing for subsequent exploration. The adopted geostatistical methods and other approach utilized in this research are effective, indicative of handling bulk exploration data for decision and subsequent exploration.

Stream sediment surveys support early-stage reconnaissance mineral exploration and regional assessment programmes, enhanced by recent improvements in analytical method detection limits, continuously improving mineral chemistry, and new approaches to the interpretation of geochemical data. Sediment surveys may be used to predict catchment basin lithology, mineralization type based on pathfinder geochemistry, and geological features based on indicator mineral chemistry. Sediment surveys that target a finer-fraction sediment sample led to the discovery of the La Colosa gold deposit, Colombia. The Batu Hijau porphyry Cu–Au deposit in Indonesia was discovered based on an anomalous clay-sized fraction sample 12 km downstream. In an arid region with poorly developed drainages and minor topographic relief, the Ag-base-metal Navidad District in Argentina was discovered with clay-fraction sediment geochemistry. Heavy mineral concentrate (HMC) sediment surveys that include mineral chemistry determinations have led to global diamond discoveries. HMC surveys contributed to discovery of the Ring of Fire Ni–Cu–PGE and chromite district, Ontario, Canada. Discoveries and geochemical mapping can assist advancement of the application of stream sediment geochemistry in those global areas for which lithologies and deposits are exposed. Stream sediment surveys continue to be one of the most cost-effective geochemical methods for covering large areas for mineral exploration. Thematic collection: This article is part of the Reviews in Exploration Geochemistry collection available at: https://www.lyellcollection.org/topic/collections/reviews-in-exploration-geochemistry [ABSTRACT FROM AUTHOR]

Conducted within the scope of geochemical exploration in eastern Thailand, this study aims to detect geochemical anomalies and potential mineral deposits. The objective was to interpret intricate spatial dispersion patterns and concentration levels of deposit pathfinder elements, specifically arsenic (As), copper (Cu), and zinc (Zn), using a comprehensive array of stream sediment geochemistry data. Methodologies involved integrating multifractal properties and traditional statistics, facilitated by the GeoDAS and ArcGIS platforms as instrumental analytical tools. In total, 5376 stream sediment samples were collected and evaluated, leading to the development of an in-depth geochemical map. The results indicated distinct geological units marked by substantially elevated average values of the aforementioned elements. Identification of geochemical anomalies was achieved through the spatial distribution method and the subsequent application of the spectrum-area (S-A) multifractal model. An intriguing link was found between high As concentrations and gold deposits in the area, suggesting As as a viable pathfinder element for gold mineralization. The anomaly maps, generated from the stream sediment data, spotlighted potential zones of interest, offering valuable guidance for future mineral exploration and geological inquiries. Nonetheless, it is vital to recognize that the increased values noted in these maps may be influenced by regional geological factors, emphasizing the necessity for a diverse set of analytical methods for accurate interpretation. This study's significance lies in its pioneering use of the S-A multifractal model in geochemical data analysis. This innovative approach has deepened our comprehension of geochemical dispersion patterns and improved the precision of mineral exploration. [ABSTRACT FROM AUTHOR]

BACKGROUND Rare earth elements were used as geochemical tracers usually to provide important information for revealing the genesis of rocks and minerals, geochemical conditions of diagenesis and mineralization, material sources and magmatic differentiation and evolution, due to their stable chemical properties and high degree of uniformity. Therefore, it was very important to develop a method for rapidly and accurately determining the contents of rare earth elements in geological samples. In addition, due to the complex matrix of geological samples, most samples needed to be acid-dissolved in pre-treatment, and the amount of acid-dissolved reagents was large. The acid mist generated in the process of sample dissolution was harmful to the experimental personnel and the labor intensity of batch sample pretreatment was high. OBJECTIVES To establish a rapid and accurate method for batch determination of rare earth elements in geological samples. METHODS A method was developed to measure 15 rare earth elements such as La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Y in soil and stream sediment by inductively coupled plasma-mass spectrometry with Rh and Re as the internal standard, in which the pre-treatment process of “acid addition—digestion—acid removal—constant volume—shaking” was controlled by software and completed with an automatic graphite digestion instrument. The digestion procedure, the effects of digestion mixed acid, precision, accuracy, and detection limit of the method were studied by soil and stream sediment reference materials including GBW07402, GBW07446, GBW07448, GBW07454, GBW07456, GBW07457, GBW07304a, GBW07307a, GBW07308, GBW07312, GBW07359 and GBW07361. RESULTS The results showed that the amount of mixed acids was 4mL consumed by soil and stream sediment digestion according to optimized digestion procedure. The absolute values of relative error and ΔlgC of rare earth elements were 0-6.67% and 0-0.028, respectively. Therefore, the measured values were consistent with certified values. The relative standard deviation (RSD) of rare earth elements was 0.97%-4.62%, which is lower than the RSD of the electric plate digestion method. CONCLUSIONS The precision, accuracy and detection limit of the method meet the requirements of the specification of testing quality management for geological laboratories-part 4 “Analysis methods for regional geochemical sample”. The precision of the method is better than electric plate digestion method. The amount of mixed acid used in the method is 4mL, which is much lower than that in the electric plate digestion method, the corresponding environmental pollution is also reduced. The detection limit of most rare earth elements in the method is lower than that in the standard method. The pre-processing of the automatic digestion method only requires the experimental personnel to weigh the sample and place it in the digestion tube in the automatic graphite digestion instrument and the whole process of dissolution is then automated. The automation degree is high, which guarantees the safety of experimental personnel to the greatest extent and can be applied to the testing of batch samples.

Several techniques, such as chemical methods and inductively coupled plasma mass spectrometry (ICP-MS), are available to accurately determine element content. However, they are time-consuming, labor-intensive, or expensive. Portable X-ray fluorescence spectrometry (pXRF) can be applied in various scenarios, with significantly higher efficiency and cost-effectiveness than laboratory methods. However, it also has limitations such as lower detection capability, relatively high detection limits, and lower accuracy than laboratory methods. In this study, we focused on applying pXRF to determine the elemental content of sediment samples and investigate its use in mineral exploration. A variety of factors influencing the results of pXRF analysis were analyzed. Our results showed that pXRF could detect more than 30 elements in stream sediments. The reliability of pXRF's measurements was affected by factors such as the kind of element, sediment particle size, sample grinding treatment, count time, averaged element content, standard deviation of content, and range of content variation. The combination of pXRF analysis and laboratory analysis of partial samples is adequate for establishing a multi-element content inference equation. With this equation, it is possible to effectively infer the content gradient of elements, which will provide valuable support for mineral resource exploration. [ABSTRACT FROM AUTHOR]

Copyright of Geology & Resources is the property of Geology & Resources Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The stream sediment (SS) records evolution information of the water system structure and sedimentary environment in specific regions during different geological periods, which is of great significance for studying the ancient planetary environment and the law of water system changes. Based on the SS of different geographical environments on Earth, remote laser-induced breakdown spectroscopy (remote-LIBS) technology combined with the multidimensional scaling-back propagation neural network (MDS-BPNN) algorithm was used to conduct an in-depth analysis of remote qualitative and quantitative detection of the elemental composition and content of SS. The results show that the detection system based on remote LIBS combined with an artificial neural network algorithm can achieve an ideal quantitative analysis of major and trace elements. The coefficients of determination (R2) of the test set for major elements is greater than 0.9996, and the root mean square error (RMSE) is less than 0.7325. The coefficients of determination (R2) of the test set for trace elements is greater than 0.9837, and the root mean square error is less than 42.21. In addition, for the application scenario of exploring extraterrestrial life, biominerals represented by stromatolite phosphorite (SP) are easy to form sand and enter into SS under weathering. Therefore, this paper discusses the feasibility of using remote-LIBS technology to detect and identify such minerals under the disappearance of SPs' macro- and micro-characteristics. From our research, we can find that remote-LIBS technology is the preferred candidate for discovering dust-covered biominerals. In geological environments rich in water system sedimentary rocks, such as Mars' ancient riverbeds, LIBS technology is crucial for deciphering the "life signals" hidden in the Martian sand. [ABSTRACT FROM AUTHOR]

Geochemical survey of stream sediments is an effective technology for mineral prospecting. The extraction of geochemical anomalies in stream sediments based on catchment basins has always been one of the research hotspots.The catchment basin analysis method is proposed based on Sample Catchment Basin Analysis (SCBA)in this paper, and it is used to identify geochemical anomalies in the Wulasitai region, East Kunlun Orogenic Belt in Qinghai Province.Catchment basins are divided by a high-precision DEM, and the Au, Ag, and Pb factor loadings of 1∶50000 stream sediments are measured by the catchment basin analysis. During the extraction process, a variety of geomorphic parameters such as main stream slope, relief ratio, catchment basin area, are used as the sediment delivery ratios for residual correction calculation, and the geochemical background and anomalies are separated by the C-A fractal modeling. The anomaly extraction results show that the area of the catchment basin is the most suitable parameter as the sediment delivery ratio to participate in the downstream attenuation correction. The catchment basin method can effectively identify and extract geochemical anomaly information.Anomalies correspond well to the spatial location of ore deposits, and can provide beneficial information for the next step of mineral prospecting.

In order to achieve a breakthrough in gold prospecting in Qixia area, 16 elements mainly including Au and Ag which were on the basic of the stream sediment survey in 1∶ 50 000 scale of the Biguo area was analyzed. The distribution characteristics, enrichment and dispersion characteristics and abnormal characteristics of elements were studied, and the R-type clustering analysis and factor analysis of each element were carried out. The results show that the anomalies of Au dominated metallogenic elements in the study area are of high intensity, large scale and good coincidence, which are mainly distributed in the main metallogenic and secondary fault zones in the area. In combination with the geological, geophysical and mineral characteristics in the area, five gold prospecting prediction areas are delineated. There is one deep and peripheral A-level prediction area of Hushan gold mine, One deep B-level prediction area of Taiqian gold mine,and three C-level prediction area in Suntuan daheya, sansukuang and Dahuayuan area. [ABSTRACT FROM AUTHOR]

BACKGROUND: Rare earth elements were used as geochemical tracers usually to provide important information for revealing the genesis of rocks and minerals, geochemical conditions of diagenesis and mineralization, material sources and magmatic differentiation and evolution, due to their stable chemical properties and high degree of uniformity. Therefore, it was very important to develop a method for rapidly and accurately determining the contents of rare earth elements in geological samples. In addition, due to the complex matrix of geological samples, most samples needed to be acid-dissolved in pre-treatment, and the amount of acid-dissolved reagents was large. The acid mist generated in the process of sample dissolution was harmful to the experimental personnel and the labor intensity of batch sample pretreatment was high. OBJECTIVES: To establish a rapid and accurate method for batch determination of rare earth elements in geological samples. METHODS: A method was developed to measure 15 rare earth elements such as La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Y in soil and stream sediment by inductively coupled plasma-mass spectrometry with Rh and Re as the internal standard, in which the pre-treatment process of “acid addition—digestion—acid removal—constant volume—shaking” was controlled by software and completed with an automatic graphite digestion instrument. The digestion procedure, the effects of digestion mixed acid, precision, accuracy, and detection limit of the method were studied by soil and stream sediment reference materials including GBW07402, GBW07446, GBW07448, GBW07454, GBW07456, GBW07457, GBW07304a, GBW07307a, GBW07308, GBW07312, GBW07359 and GBW07361. RESULTS: The results showed that the amount of mixed acids was 4mL consumed by soil and stream sediment digestion according to optimized digestion procedure. The absolute values of relative error and ΔlgC of rare earth elements were 0-6.67% and 0-0.028, respectively. Therefore, the measured values were consistent with certified values. The relative standard deviation (RSD) of rare earth elements was 0.97%-4.62%, which is lower than the RSD of the electric plate digestion method. CONCLUSIONS: The precision, accuracy and detection limit of the method meet the requirements of the specification of testing quality management for geological laboratories-part 4 “Analysis methods for regional geochemical sample”. The precision of the method is better than electric plate digestion method. The amount of mixed acid used in the method is 4mL, which is much lower than that in the electric plate digestion method, the corresponding environmental pollution is also reduced. The detection limit of most rare earth elements in the method is lower than that in the standard method. The pre-processing of the automatic digestion method only requires the experimental personnel to weigh the sample and place it in the digestion tube in the automatic graphite digestion instrument and the whole process of dissolution is then automated. The automation degree is high, which guarantees the safety of experimental personnel to the greatest extent and can be applied to the testing of batch samples. [ABSTRACT FROM AUTHOR]

In this study, groundwater, stream water, and stream sediment samples were collected from a coal mine area in Dazhu, Southwestern China, and hydrogeochemical, multivariate, and X-ray analyses were conducted to examine the effects of coal mine pollution. The groundwater and stream samples were slightly acidic to alkaline (6.7 to 8.2). Typically, the water samples were dominated by Ca2+ + Mg2+–HCO3− and Ca2+ + Mg2+–Cl−. SO42− originates from gypsum dissolution and pyrite oxidation, and Ca2+ and Mg2+ may be related to the dissolution of carbonate. According to the Chinese standard and World Health Organization guidelines, the water in the coal mine area is of good quality in terms of its physical and chemical properties, except for the concentration of Mn and Fe, with values of 1925.14 μg/L and 12,872.88 μg/L, respectively. A principal component analysis revealed two groups in which the concentration of metals and metalloids in stream sediments are affected by the coal mine drainage. The Mn and Fe average concentration in the downstream Kongjiagou drain sediment samples was 2035.1 ppm and 6%, respectively. These values were higher than the average Mn and Fe concentration in Xiaojiagou at 453.1 ppm and 2.9%, respectively. Both the Mn and Fe concentration were higher than the background values (640 ppm and 4.4%). [ABSTRACT FROM AUTHOR]

The Pouma area is located within the Yaoundé domain of the Pan-Africa Fold Belt in Cameroon. The objective of this study was to examine the geochemical distributions of elements in stream sediment so as to assess the trace metal contamination, sources of pollution and ecological risks assessment. Samples were obtained by panning and analysed by inductively coupled plasma-mass spectrometer. Stream sediments exhibit high content of Fe2O3 (0.48–8.86%), Mn (142–887 ppm), Th (12 to > 200 ppm), Zr (0.8–174 ppm), Sr (3–106 ppm), Au (18.9 to > 10,000 ppb), V (5–85 ppm), Y (9.62–101 ppm), rare earth elements (ΣREE = 181–3364 ppm), and depleted in the rest of elements. Factor analysis shows up to five factors accounting for 88.74% of cumulative variance. The pollution load index (PLI: 1.1–8.1), enrichment factor (EF: 0.01–1221), integrated nemerow pollution load index (NIPI: 3.57–25.93) and potential ecological risk index (RI: 3–7504) of silver (Ag), aluminum (Al), cadmium (Cd), copper (Cu), iron (Fe), mercury (Hg), nickel (Ni), lead (Pb), thorium (Th), uranium (U), yttrium (Y), zinc (Zn) and zirconium (Zr) indicate sediments contamination and metal pollution. Natural and metal input assessment reveals that the dominantly mafic lithology, quarrying and domestic activities as well as agricultural practices are the main source of metal contamination in Pouma area. The results of this study provide some valuable insights as it concerns the sediment assessment approach, which can be used to design and plan strategic sediment management programmes in the Pouma area. Article Highlights: • Pouma area is located within the Yaoundé domain of the Pan-Africa Fold Belt in Cameroon • The pollution parameters obtained in the Pouma area indicate contamination and metal pollution • Natural and anthropogenic metal input are the main sources of metal contamination in Pouma area [ABSTRACT FROM AUTHOR]

This study describes the geochemical characteristics of the metals and the environmental pollution of sediments of upstream in Ulutaş Erzurum, Turkey. Stream sediment samples were taken from 93 sites. The majority of samples showed high Ag, As, Au, Cu, Fe, Mn, Pb and Zn concentrations and were the major pollutants in the study area. Analytical data were evaluated by statical methods. The total variance of the three factors obtained from the data was determined as 55.66%. Associated elements are as follows: Ag–Cu–Mn–Mo–S–Se–Zn, As–Pb–Sb and Cr–Ni–W. Factor 1 is close to mineralization and shows mechanical enrichment (Ag, Cu, Mn, Mo, S, Se and Zn). Factor 2 (As, Pb, Sb and Bi) probably indicates hydromorphic transport with water solutions. Factor 3 (Au, Cr, W and Ni) indicates that granodioritic rocks are weathered and associated with these rocks. Statistical analyzes were made to determine the concentration values and distribution of the elements in the studied stream sediments. Ag, As, Au, Cu, Fe, Mn, Mo, Pb, Sb and Zn elements show the anomaly distributions in the study area. The anomalies seen especially for Ag, As, Fe, Mn and Pb elements show very high anomaly with a strong contrast to other areas. [ABSTRACT FROM AUTHOR]

The identification of anomalies within stream sediment geochemical data is one of the fastest developing areas in mineral exploration. The various means used to achieve this objective make use of either continuous or discrete field models of stream sediment geochemical data. To map anomalies in a discrete field model of such data, two corrections are required: background correction and downstream dilution correction. Topography and geomorphology are important factors in variations of element content in stream sediments. However, few studies have considered, through the use of digital terrain analysis, the influence of geomorphic features in downstream dilution correction of stream sediment geochemical data. This study proposes and demonstrates an improvement to the traditional downstream dilution correction equation, based on the use of digital terrain analysis to map single‐element anomalies in stream sediment geochemical landscapes. Moreover, this study compares the results of analyses using discrete and continuous field models of stream sediment geochemical data from the Xincang area, Tibet. The efficiency of the proposed methodology was validated against known mineral occurrences. The results indicate that catchment‐based analysis outperforms interpolation‐based analysis of stream sediment geochemical data for anomaly mapping. Meanwhile, the proposed modified downstream dilution correction equation proved more effective than the original equation. However, further testing of this modified downstream dilution correction is needed in other areas, in order to investigate its efficiency further. [ABSTRACT FROM AUTHOR]

40K, 226Ra, 232Th, 238U, and 137Cs massic activities were determined by gamma-spectrometry in limestones, marls, stream sediments, and soils of Kaštela Bay (Adriatic Sea, Croatia) coastal area. Their distribution, sources and potential influencing factors were studied. The lowest 40K, 226Ra, 232Th, and 238U massic activities were determined in limestones and the highest in soils, with the following median values, respectively: 7.2, 14, 0.8, and 5.3 Bq/kg in limestones and 518, 72, 71, and 31 Bq/kg in soils. All four radionuclides were of natural origin and reflected background values of the karstic area influenced by flysch/marl and terra rossa soil. Local TENORM disposal site did not influence the study area, but it will be needed to study its potential influence on marine sediments. Strong disequilibrium between 226Ra and 238U was found in limestones s.l. and soils, but not in marls and only moderately in stream sediments. This implies that limestones are more susceptible to selective 238U leaching than marls, and soils more than stream sediments. 137Cs was the only radionuclide of anthropogenic origin, with a global source only. It was detected in stream sediments and soils with median values of 5.4 and 31 Bq/kg, respectively. 137Cs distribution was more heterogeneous in stream sediments than in soils, but soils generally presented higher activities. Soil is considered the most important reservoir of 137Cs and its potential source. [ABSTRACT FROM AUTHOR]

Mercury (Hg) release from contaminated legacy sites is a large contributor to riverine ecosystems and can represent a significant local and regional environmental issue even long after the initial site contamination. Understanding processes of in-stream species transformation is therefore important to assess the fate and bioavailability of the released Hg. In this study, we investigated in-stream Hg transformation processes with analyses of Hg binding forms and Hg stable isotopes. Stream sediments were collected downstream of a former kyanization facility (Black Forest, SW Germany), where highly soluble Hg(II)-chloride (HgCl2) was used as an anti-fouling agent to treat timber. Exfiltration of partly anoxic, contaminated groundwater with Hg concentrations of up to 700 µg L-1 into the adjacent Gutach stream is the main source of Hg to sediments. Total Hg concentrations in the stream bottom sediments (<2 mm) ranged from background values of 6.3 µg kg-1 upstream of the contaminated site to 77 mg kg-1 near the location of exfiltration of contaminated groundwater. A five-step sequential extraction procedure and Hg pyrolytic thermal desorption (PTD) analyses indicated changes in Hg binding forms in the sediments along the flow path towards a higher proportion of organically bound Hg. A large shift towards negative δ202Hg values was observed downstream of the contaminated site (change of ≈2?) along with a minor offset in mass-independent fractionation. Binary mixing models based on Hg isotope ratios using one industrial and different natural background endmembers were tested to estimate their respective contribution of Hg to the sediments but failed to produce plausible allocations. Based on the observed changes in isotopic composition, total Hg concentrations and Hg binding forms, we propose that the large extent of fractionation observed in downstream sediments is the result of a combination of kinetic isotope effects during sorption, redistribution of Hg within the sediment and the preferential transport of Hg associated with the sediment fine fraction. These results highlight the importance of transformation processes when assessing the sources and fate of Hg in environmental systems and show limitations of using simple mixing models based on Hg stable isotopes. [ABSTRACT FROM AUTHOR]

Abstract We present this manuscript as a methodological approach and general guidelines for geochemical mapping and background/baseline projects for environmental assessment in tropical areas. A case study was carried out in the Itacaiúnas River watershed (IRW), Eastern Amazon, to fill in a gap in knowledge on the distribution of chemical elements, particularly those potentially toxic, in the near-surface environment of the area. The high-impact results of this research project revealed the need for similar scientific investigation across the globe with the implementation of a systematic methodology. The study shows, for example, the importance of well-planned field activities, multi-medium sampling, analytical methods, laboratory procedures, database construction, and general aspects of data processing and statistical treatment. The importance of this contribution is that it can be used as a reference in support of geospatial analysis in research within the scope of geochemical mapping and background-baseline projects. The database is accessible through a web-based geographic information system front-end; a Geochemical Atlas of the IRW will be available as soon as possible.

This study serves the purpose of generating a geochemical Fe-bearing potential map. Stream sediment geochemical survey was employed by collecting 843 samples for analyzing 19 elements and oxides. Taking preprocessing of data (e.g. outlier correction and data normalization) into consideration, a Concentration–Number (C-N) fractal model was used to separate different geochemical populations of Fe2O3, TiO2, V and the main multi-element factor in close spatially association with the Fe targeting. A prediction-area (P-A) plot was drawn for each variable to determine the weight of each geochemical indicator. Results indicate that the main geochemical factor with an ore prediction rate of 73%, has occupied 27% of the Esfordi area as favorable zones for further mining propsectivity. The Esfordi as a favorable Fe-bearing zone is of special interest in the NE of the Bafq mining district that hosts important “Kiruna-type” Magnetite-Apatite deposits. In addition, a synthesized indicators map was prepared through implementing a data-driven multi-class index overlay in a similar fashion to the previous version of the method, upon which geochemical potential zones were mostly in the NE part of the Esfordi, intimately linked with intense fault density map. The significance of this study lies in localizing of the most geochemical favorable zones through simultaneous consideration of the C-N and P-A plots accompanied with the incorporation of known active mines and prospects to determine indicator weight. Of note is that the Mineral Potential Mapping (MPM) has higher efficiency over each geochemical indicator with an ore prediction rate of 78% and area occupation of 22%.

Mercury (Hg) release from contaminated legacy sites is a large contributor to riverine ecosystems and can represent a significant local and regional environmental issue even long after the initial site contamination. Understanding processes of in-stream species transformation is therefore important to assess the fate and bioavailability of the released Hg. In this study, we investigated in-stream Hg transformation processes with analyses of Hg binding forms and Hg stable isotopes. Stream sediments were collected downstream of a former kyanization facility (Black Forest, SW Germany), where highly soluble Hg(II)-chloride (HgCl2) was used as an anti-fouling agent to treat timber. Exfiltration of partly anoxic, contaminated groundwater with Hg concentrations of up to 700 μg L−1 into the adjacent Gutach stream is the main source of Hg to sediments. Total Hg concentrations in the stream bottom sediments (

Geochemical baselines are crucial to explore mineral resources and monitor environmental changes. This study presents the first Laos geochemical baseline values of 69 elements. The National-scale Geochemical Mapping Project of Lao People's Democratic Republic conducted comprehensive stream sediment sampling across Laos, yielding 2079 samples collected at 1 sample/100 km2, and 69 elements were analyzed. Based on the results of LGB value, R-mode factor analysis, and scatter plot analysis, this paper analyzes the relationship between the 69 elements and the geological background, mineralization, hypergene processes and human activities in the study area. The median values of element contents related to the average crustal values were: As, B, Br, Cs, Hf, Li, N, Pb, Sb, Zr, and SiO2, >1.3 times; Ba, Be, Cl, Co, Cr, Cu, F, Ga, Mn, Mo, Ni, S, Sc, Sr, Ti, Tl, V, Zn, Eu, Al2O3, Tot.Fe2O3, MgO, CaO, and Na2O, <0.7 times; and Ag, Au, Bi, Cd, Ge, Hg, I, In, Nb, P, Rb, Se, Sn, Ta, Th, U, W, Y, La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and K2O, 0.7–1.3 times. R-mode factor analysis based on principal component analysis and varimax rotation showed that they fall into 12 factors related to bedrock, (rare earth, ferrum-group, and major Al2O3 and K2O elements; mineralization–Au, Sb, and As) and farming activities–N, Br, S, and C). This study provides basic geochemical data for many fields, including basic geology, mineral exploration, environmental protection and agricultural production in Laos. [ABSTRACT FROM AUTHOR]

We present this manuscript as a methodological approach and general guidelines for geochemical mapping and background/baseline projects for environmental assessment in tropical areas. A case study was carried out in the Itacaiúnas River watershed (IRW), Eastern Amazon, to fill in a gap in knowledge on the distribution of chemical elements, particularly those potentially toxic, in the near-surface environment of the area. The high-impact results of this research project revealed the need for similar scientific investigation across the globe with the implementation of a systematic methodology. The study shows, for example, the importance of well-planned field activities, multi-medium sampling, analytical methods, laboratory procedures, database construction, and general aspects of data processing and statistical treatment. The importance of this contribution is that it can be used as a reference in support of geospatial analysis in research within the scope of geochemical mapping and background-baseline projects. The database is accessible through a web-based geographic information system front-end; a Geochemical Atlas of the IRW will be available as soon as possible. [ABSTRACT FROM AUTHOR]

The current investigation concern Tiouit region in order to perceive potential mining zones. Remote sensing data were the main component to process. In order to spot geochemical anomalies associated with the target zones, multispectral ASTER data, gamma-ray spectrometry, and stream sediment data were used. Crosta and SAM applications granted to map a spatial distribution of propylitic, phyllic, clay, and ferruginous alteration zones. The normalized ratios let the delineation of potassic alteration zones, including the Tiouit gold mine characterized by an intense alteration in the Ikniwn granodiorite. Thus, the potassic alteration zones are consistently co-located with the tectonic structures materialized by strong fracturing densities. The stream sediment geochemical investigation revealed that the cited areas have an important potential of mineralization, with high concentrations of As (136 g/t), Cu (91 g/t), Pb (141 g/t), Zn (392 g/t), Ag (3 g/t), Mo (11 g/t), Mn (0.2 g/t), and Fe (10.63 %). [ABSTRACT FROM AUTHOR]

The stream sediment (SS) records evolution information of the water system structure and sedimentary environment in specific regions during different geological periods, which is of great significance for studying the ancient planetary environment and the law of water system changes. Based on the SS of different geographical environments on Earth, remote laser-induced breakdown spectroscopy (remote-LIBS) technology combined with the multidimensional scaling-back propagation neural network (MDS-BPNN) algorithm was used to conduct an in-depth analysis of remote qualitative and quantitative detection of the elemental composition and content of SS. The results show that the detection system based on remote LIBS combined with an artificial neural network algorithm can achieve an ideal quantitative analysis of major and trace elements. The coefficients of determination (R2) of the test set for major elements is greater than 0.9996, and the root mean square error (RMSE) is less than 0.7325. The coefficients of determination (R2) of the test set for trace elements is greater than 0.9837, and the root mean square error is less than 42.21. In addition, for the application scenario of exploring extraterrestrial life, biominerals represented by stromatolite phosphorite (SP) are easy to form sand and enter into SS under weathering. Therefore, this paper discusses the feasibility of using remote-LIBS technology to detect and identify such minerals under the disappearance of SPs’ macro- and micro-characteristics. From our research, we can find that remote-LIBS technology is the preferred candidate for discovering dust-covered biominerals. In geological environments rich in water system sedimentary rocks, such as Mars’ ancient riverbeds, LIBS technology is crucial for deciphering the “life signals” hidden in the Martian sand.

Radiological risks associated with 40 K, 226Ra and 232Th massic activities in limestones, marls, stream sediments and soils of the Kaštela Bay (Croatia) coastal area were assessed by calculating outdoor absorbed dose rates in air (D), annual outdoor effective dose rates (Def), radium equivalent activities (Raeq) and external hazard indices (Hex). Radionuclides relative contributions to D and Hex were determined for all four types of samples as well as their total contribution to Hex in all samples. D, Def, Raeq and Hex were the lowest in limestones and the highest in soils. Maximum Raeq and Hex in soil were below the recommended values of 370 Bq/kg and 1.0. No adverse radiological effects were determined in the researched area. The most important contribution to D and Hex in limestones was almost exclusively from 226Ra, in marls from 40 K, in stream sediments from 226Ra and in soils from 232Th. The most significant total contribution to Hex in all samples came from 226Ra and 232Th, and the lowest came from 40 K. 226Ra showed the largest variability of its total contribution to Hex, with tendency to higher values. Special attention should be given to 226Ra when studying radiological risks in typical karstic areas, irrespectively of other possible influences of geological background. [ABSTRACT FROM AUTHOR]

A regional-scale stream sediment geochemical sampling was carried out with an average sampling density of one sample per nine square-kilometre in Kiteto District, Manyara Region. A total of 358 stream sediment samples were collected and analysed for major and trace elements by X-ray fluorescence (XRF) and fire assay with atomic absorption spectrometry (AAS) finish methods. In this study, Factor and Principal Component Multivariate (FPCM) analyses have been used to the stream geochemical data to delineate potential mineralization zones by plotting correlated factors as geochemical anomaly maps. Four factors that account for 73.7% of the total variance of the stream sediment geochemical data were established. Factor 1: Ni-Ba-Co-Cu-Sr which possibly defines the underlying metamorphosed granitic units with some contribution from mafic and ultramafic rocks. Factor 2: Cr-Zn-Mn which defines crustal forming elements reflecting the mafic rocks. Factor 3 which entails Rb and Pb probably attributed to metamorphosed granitic lithology. Factor 4 is arsenic, a chalcophile element with affinity to sulfide phases. The FPCM analyses have been successfully in delineating potential target areas for gold, nickel and copper exploration in the study area. [ABSTRACT FROM AUTHOR]

The geochemistry of stream sediments is widely used in the study of the mineral exploration, and the separation of geochemical anomalies from the background is one of its most important steps. In this research, geochemical data of stream sediments were processed using TOPSIS method, which is a multivariate decision method. Using the decision matrix and solving the distance between ideal and non-ideal, geochemical anomalies were obtained without the need for statistical processing and without relation to the form of data distribution. For this purpose, 620 samples of sediments taken from streams in the Ahar region in northwestern Iran were used, and the results showed that geochemical data can be successfully prioritized to each number. [ABSTRACT FROM AUTHOR]

Anomaly patterns of magmatic–hydrothermal polymetallic and structurally controlled orogenic gold deposits in the Qinling Orogen were evaluated by an integrated approach of tectonic division, factor analysis, and concentration–area (C–A) modeling. In order to limit the unique effects within different tectonic terranes on rocks and mineralization throughout the whole area, the evaluation was performed in the different parts of the Qinling Orogen, namely the southern North China Block, North and South Qinling Orogen, and the northwestern margin of the South China Block. Different element associations derived by factor analysis and the distributions of factor scores can roughly distinguish metallogenic signatures from geological backgrounds controlled by the regional lithology. Geochemical thresholds of different ore-forming elements were determined by C–A fractal modeling to distinguish anomalies of metals from their background, namely 2.7 ppb for Au, 220 ppm for Ag, 54 ppm for Pb, 160 ppm for Zn, 44 ppm for Cu and 1.4 ppm for Mo. The results suggest that metal anomalies of magmatic–hydrothermal deposits are generally characterized by Cu(–Mo–Au) and Ag–Pb–Zn, with circular or irregular spatial distribution, which can be distinguished within individual tectonic units by factor analysis and C–A fractal modeling. However, these methods were less effective in locating orogenic gold deposits, which are characterized by linear anomaly patterns. A new method, named lineament density, is thus proposed here to characterize linear structures concentration of faults, cleavage and fracture and its relationship with metal anomalies. This proposed method proves to be effective through the prediction-area (P-A) plot and, thus, it was applied successfully to locate anomalies associated with orogenic gold deposits. This study highlights that magmatic–hydrothermal polymetallic and orogenic gold deposits have contrasting anomaly patterns, which should be delineated by specifically suitable exploration methods or a combination of suitable methods. [ABSTRACT FROM AUTHOR]

[Display omitted] • A stream sediment geochemical survey is conducted in a pilot area in central Iran. • Elastic velocities, porosity, and Schmidt hammer rebound values are measured. • An index for rock weathering rate in the case study is presented. • Introducing the weatherability explains a part of geochemical variability. • Regression model has some limitations highlighted by the results. The chemical composition of stream sediments is heavily influenced by weathering processes occurring in upstream lithological units. Despite their importance, these processes are frequently ignored in the examination of stream sediment geochemical data when identifying mineralized zones. Instead, existing geochemical background estimation procedures rely on the area size of upstream rocks as an indicator of their contribution to elemental concentrations of sediments. To address this limitation, a stream sediment geochemical survey was conducted in a pilot area in central Iran, and the physico-mechanical properties of upstream rock types, including elastic velocities, porosity, and Schmidt hammer rebound values, were evaluated. A new weathering index, "W ij ," was developed, utilizing proxies of rock weathering to estimate the geochemical background attributed to lithology at sediment sampling sites. The regression model was constructed by combining weathering proxies (W ij) with other independent variables, including the presence or absence of rocks in catchments, area size (X ij), and the weathering-corrected contributing factor (X ij W ij). The results suggested the significant capability of weathering proxies in explaining the geochemical variability of major elements such as Al, K, Fe, Ca, and Na. However, the regression model using weathering-corrected contributing factors delivered better overall accuracy than other independent variables. Nevertheless, our results also identified some limitations of the application of regression model in stream sediment data analysis. [ABSTRACT FROM AUTHOR]

Northern Tibet exhibits abundant placer gold deposits, with a longstanding history of mining activities. Despite the widespread placer gold occurrences, the reports on the primary rock gold deposits or occurrences remain scarce. The central Lhasa terrane in northern Tibet hosts well-developed Zenong Group volcanic rocks, indicating great potential for the exploration of porphyry-epithermal copper (gold) deposits. Here, we select the Dangreyongcuo area in this region to investigate its metallogenetic potentiality, through a comprehensive 1:50,000 stream sediment geochemical survey, analyzing 12 elements (Au, As, Sb, Ag, Te, Cu, Pb, Zn, W, Sn, Bi, and Mo), and a detailed geological mapping. We aim to identify gold-related mineralization anomalies and provide clues for further bedrock gold exploration in this region. Based on the stream sediment geochemical data, zones 1–4, have been delineated using single-element indicator Au and element association indicator Au + As + Sb, which was determined through robust principal component analysis (RPCA) and using the exploratory data analysis (EDA) method. Subsequent validation exercises evaluating these four delineated zones reveal that Zone 1, Xinlong-Langmeila area, is the most promising prospect due to its high element concentrations, large size, and marked coincidence of element assemblages (also referred to as high-large-coincidence anomalies; HLCAs) and its characteristics are in line with those of epithermal deposits. Notably, the Xinlong deposit represents the first documented epithermal gold deposit hosted within the Zenong Group volcanic rocks. The identification of this deposit offers valuable insights and strategic directions for the broader understanding of Zenong Group volcanic rocks across the central Lhasa terrane. Additionally, subsequent strategies have been proposed for mineral exploration at both Xinlong camp and regional scales. • Gold anomalies were detected in the western Dangreyongcuo area, Tibet. • Xinlong deposit is a newly discovered high-sulfidation epithermal gold deposit. • Xinlong gold deposit is linked to Zenong Group volcanic rocks. • Promising prospecting potential exists within regional Zenong Group volcanic rocks. [ABSTRACT FROM AUTHOR]

Due to the complex characteristics of geological structures, identifying geochemical anomalies in valuable deposits using regional geochemical datasets of stream sediments is challenging. In this study, an effective combined method was proposed to solve the problem of anomaly identification in multibackground areas. First, samples were classified into different clusters through the k-means clustering method using major elements/minerals (such as SiO 2 and Na 2 O) that can reflect the lithology and were chosen as classification indicators. Considering the double restriction of the contour coefficient and lithological background, each sample within the same cluster was considered to have the same background. Then, the residual value between each sample and the mean data of adjacent samples within the same cluster was calculated, and the original data of each sample were replaced with the ratio (a new parameter defined as the residual contrast value) of the residual value and the anomaly threshold obtained for the corresponding cluster. Finally, geochemical maps and anomaly maps were generated using the residual contrast values. A practical example involving a regional geochemical dataset of stream sediments in Hunan, China, was examined in detail to clarify the procedure. Moreover, a comparative analysis through success rate curves of the percentage of deposits correctly determined was performed between the traditional method, singularity method and new combined method. The results showed that the anomalies identified by the proposed method were closely associated with known deposits, and the residual contrast value, which considers the effects of the lithological background, random error, and structural anomalies, could eliminate the influence of lithology and enhance weak anomalies. Moreover, the geological significance of this method is clear, and the calculation procedure is simple. Thus, this method could be applied for identifying regional geochemical anomalies in multibackground areas and could be used as a guide for new exploration targets. • Proposed an effective combined method for geochemical anomaly identification in multibackground areas. • Proposed a new parameter: residual contrast value • Lithological, random error, and structural anomaly are considered in the method. • Anomalies identified by this method has stronger association with the known deposits. • A comparative analysis was made through success rate curves of the percentage of deposits correctly determined among different methods. [ABSTRACT FROM AUTHOR]

In this study, groundwater, stream water, and stream sediment samples were collected from a coal mine area in Dazhu, Southwestern China, and hydrogeochemical, multivariate, and X-ray analyses were conducted to examine the effects of coal mine pollution. The groundwater and stream samples were slightly acidic to alkaline (6.7 to 8.2). Typically, the water samples were dominated by Ca2+ + Mg2+–HCO3− and Ca2+ + Mg2+–Cl−. SO42− originates from gypsum dissolution and pyrite oxidation, and Ca2+ and Mg2+ may be related to the dissolution of carbonate. According to the Chinese standard and World Health Organization guidelines, the water in the coal mine area is of good quality in terms of its physical and chemical properties, except for the concentration of Mn and Fe, with values of 1925.14 μg/L and 12,872.88 μg/L, respectively. A principal component analysis revealed two groups in which the concentration of metals and metalloids in stream sediments are affected by the coal mine drainage. The Mn and Fe average concentration in the downstream Kongjiagou drain sediment samples was 2035.1 ppm and 6%, respectively. These values were higher than the average Mn and Fe concentration in Xiaojiagou at 453.1 ppm and 2.9%, respectively. Both the Mn and Fe concentration were higher than the background values (640 ppm and 4.4%).

Owing to the strong control bedrock geology may exert on the chemical composition of stream sediments, the determination of stream sediment geochemical anomalies is always affected by the lithology background in areas with variable lithologies. In this study, the expectation–maximization (EM) algorithm was used to separate lithologies of different chemical compositions in a 1: 200 000 scale regional geochemical data set of stream sediments in a lithologically complex region in Hunan province, SE China. The data set included 1024 minerogenic stream sediment samples which were analysed for Cu, La, Li, Be, Cr, Ni, Sr, V, Th, Ti and Zr. A comparison between Cu anomalies determined with and without taking into account the separation of lithologies was carried out. The result shows that stream sediment geochemical anomalies in lithologically complex regions can be determined in a more reasonable way by application of the EM clustering method. Strong but false or meaningless anomalies can be eliminated, and weak but important or meaningful anomalies are more clearly revealed. [ABSTRACT FROM AUTHOR]

Particle size exerts significant control on the concentration of elements in stream sediments and is therefore critical in stream sediment-based geochemical exploration, which has proved important in China's National Geochemical Mapping Project. There are various geographical landscapes in China with different distribution characteristics of stream sediments. Therefore, we studied the relationship between particle size and element distribution in stream sediments, which is always a crucial but challenging issue in geochemical surveys. The distributions of minerals and elements in eight size fractions of stream sediments (2–0.84, 0.84–0.42, 0.42–0.25, 0.25–0.177, 0.177–0.125, 0.125–0.096, 0.096–0.074, and <0.074 mm) from the Dongyuan W-Mo deposit in eastern China were studied. The results show that the 2–0.25 mm particle size fraction of stream sediments is composed mainly of rock debris and various minerals from broken bedrock upstream, while the <0.25 mm fraction is composed mainly of clay, individual minerals, and organic matter. The pilot survey results prove that using 2–0.25 mm as the sampling particle size fraction is better than using <0.25 mm, especially in geochemical prospecting and geological body delineation. Sampling the 2–0.25 mm particle size fraction of stream sediments can help to delineate proven ore bodies, ore-related anomalies, and geological bodies more effectively and more credibly. The suggested sampling particle size fraction for a stream sediment geochemical survey in a humid to semi-humid low mountain landscape in eastern China is therefore 2–0.25 mm, rather than the particle size fraction of <0.25 mm that was used for sampling in this area before. This paper depicts a successful example for determining the optimal sampling particle size fraction for stream sediment-based geochemical exploration. [ABSTRACT FROM AUTHOR]

Stream sediment geochemical survey is an efficient tool for regional prospecting of ore minerals. However, complex processes of dilution and enrichment made it difficult to be studied by conventional methods. One of the most important methods to separate anomalous areas are fractal and multifractal analysis; however, some techniques of the fractal analysis which are more popular and applicable, such as concentration-area, suffer from lack of a reliable interpolated map of stream sediments data. In this study, we introduce a simple workflow to separate anomalous areas in three steps: 1. a grid interpolation method is developed to produce continues geochemical surface based on geometry of Sample Catchment Basin (SCB), 2. Although U-statistics, a powerful spatial based method, has no permission to work with Stream sediment data, the grid interpolation prepares a convenience (by converting stream sediment data from vector nature into point or pixel-based data) to apply it for this type of geochemical data, 3. Finally, the fractal analysis is applied for anomaly separation. In other words, the transformation into pixel-based nature in the first step is followed by using U-statistics (or any spatial method) to compensate spatial relation among the pixels. Once an accurate interpolated map is computed in the first two steps, fractal analysis is capable to effectively separate different populations (i.e. background and anomaly) with the highest accuracy and validity. This workflow is implemented on 305 stream sediment samples from Saqez area located on western part of Iran to delineate Au mineralization. Results show that anomalous areas of Au are successfully separated in the final categorical map, which is highly matched with the location of 5 high potential zones of Au known in this area. [ABSTRACT FROM AUTHOR]

A stream survey was conducted in the Sidakan vicinity in the northeastern part of the Iraqi Kurdistan Region, which covered the catchment area of the main stream. The covered area is about 450 km2. The exposed rocks in the study area are mainly igneous with subordinate sedimentary and metamorphic rocks. The catchment area was divided into 14 sub-basins using Global Mapper software. The junction point of the valleys at the end of each sub-basin was sampled. From each junction point, 2 stream sediments were collected. The samples were sieved using the wet method into 2 mm fractions, before the fractions were subjected to x-ray fluorescence (XRF) and x-ray diffraction (XRD) analysis. The results obtained from both tests were used to calculate the concentrations of 9 elements (Cr, Ni, Co, Cu, U, Ag, V, Zn, and Cd). The element concentrations are presented in 9 concentration maps after normalizing the concentration values. Some anomalous results were found. The average concentrations of Ag and Cd were nearly 120 and 266 times higher than the background concentrations (6 mg/kg and 16 mg/ kg, respectively). The acquired data also showed interesting average concentrations for the elements Co, Cr, Ni, and U (280 mg/kg, 999 mg/kg, 375 mg/kg, and 12 mg/kg, respectively). All of these anomalous concentrations are discussed and possible reasons for their existence are given.

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Abstract In order to assess the concentrations of heavy metals in stream sediments of eastern and southeastern drainages of the Angouran Zn-Pb mine, stream sediment samples were selected from 77 stations. Results of samples analysis demonstrate that concentrations of As, Sb, Cd, Pb and Zn are higher and Co is less than the averages of upper continental crust in most stations. The elements correlation analysis indicates that there are intermediate to very strong positive correlations between Pb, Zn, Cd, Sb and As, and Co has no correlation with other elements. Investigation of distribution maps, enrichment factor and geo-accumulation index demonstrate that the highest enrichment and pollution in the study area related to Pb, Zn, Cd, Sb and As which are concentrated at the northern and northeastern parts of the study area (Allahlou-Chay catchment). Investigation of the relationship between the obtained data and geology of the study area demonstrates that the origin of these elements concentrations are geogenic and related to mineralizations and alterations. Exploitation activities at the Angouran Zn-Pb mine caused increasing the concentration of heavy metals and their entry into the surface waters which with the result of expansion of mentioned elements to northeast of study area and Allahlou-Chay catchment. Keywords: Stream sediment, Heavy metals, Spatial distribution, Geo-accumulation index, Angouran. Introduction Heavy metals are one of the most important soil contaminants which are naturally present in the soil, but large amounts of these metals are the result of human activities like mining, transportation, disposal of industrial wastewater, improper disposal of wastes and use of chemical fertilizers and pesticides (Rahimpour and Abbaspour 2014; Zare Khosh Eghbal et al. 2012). Seasonal rivers during heavy rains transfer contaminated sediments and mineral waste from adjacent mines to downstream areas and cause heavy metal dispersion. As such, studying stream sediments is one of the best ways to assess pollution. Angouran Zn-Pb mine is one of the mines that due to a large volume of extraction and mineral production has produced a lot of waste around the mine. These wastes, in turn, can cause many problems for the environment around the mine. In this study, an attempt was made to evaluate the role of mining in the environment by investigation of heavy metal concentrations in the stream sediment samples of the rivers at the east and southeast of the Angouran Zn-Pb mine (Allahlou-Chay and Kakaroud catchments). Materials and Methods In order to evaluate the environmental contamination of heavy metals at the eastern and southeastern catchments of Angouran Zn-Pb mine, 77 samples were selected from intended stations. In this stage, about 500 gr of stream sediments from a depth of 5-15 cm was selected from each station. After crushing and milling the samples, the obtained powders were dissolved by the four acid solutions and were analyzed by the ICP-OES at laboratories of Geological Survey of Iran. The studied elements in this research include As, Sb, Cd, Pb, Zn and Co. After receiving the analytical results from the laboratory, the data were processed statistically. For this purpose, statistical parameters such as the mean, median, mode, standard deviation, skewness, Kurtosis, range, minimum and maximum were analyzed for the 6 mentioned elements using SPSS 22 software. Furthermore, Kolmogorov-Smirnov test was used to examine the distribution of the normality of data. In the absence of normal data, the logarithm transformation method was used to normalize the data. In order to determine the level of stream sediments contamination to heavy metals in the study area, the enrichment factor and the geo-accumulation index were used. To survey elements distribution maps, interpolation of reverse weight weighting and pixel estimation were employed. Discussion of Results & Conclusions Evaluation of normality of data indicates that except for the cobalt, the other elements do not have a normal distribution. The results of sample analysis demonstrate that concentrations of As, Sb, Cd, Pb and Zn are higher and Co is less than the average of upper continental crust in most stations. The results of correlation between the elements indicate that Co has no correlation with other elements while others show moderate to strong positive correlations with each other. The element distribution maps in the study area demonstrate that the elements anomalies mainly locat in the northern and northeastern parts. Furthermore, these maps show that anomalies of Pb, Zn, Cd, As and Sb have an overlap with each other. The enrichment factor investigations indicate that the highest enrichment is related to Pb, Zn, Cd, As and Sb located on northeastern and eastern parts of the study area (Allahlou-Chay catchment). Moreover, in terms of geo-accumulation index, Cd, As, Sb, Pb and Zn caused the pollution of most parts of the study area especially the northeastern and eastern parts (Allahlou-Chay catchment). In general, the analysis of the result of samples from stream sediments of the study area demonstrates that the origin of investigated elements is partly natural (geogenic) and related to mineralizations and alterations. But, exploitation activities in Angouran Zn-Pb mine, weathering of ores and leaching of soils and waste damps led to increasing the heavy metals concentrations and their entrance into the current waters. This led, in turn, to expansion of heavy metal concentrations to other parts of the study area far from the mineralized region (northeastern part and Allahlou-Chay catchment). These data are in agreement with the results of Ghadimi and Nabatian (2014) showing that the water of catchments in upper levels of Angouran Zn-Pb mine show no pollution for Pb, Zn, As and Cd, while by crossing the mining site they become polluted because of these elements.

This study assessed the contamination of streams with potentially toxic elements (PTEs) in sediments around mining, quarrying, and cultivation areas in Akamkpa and environs Southeastern Nigeria. Analysis done using ICP MS technique shows that barium (Ba) and lead (Pb) recorded mean concentrations above their average shale content (ASC) in stream sediments. Chromium (Cr) exceeded Canadian Interim Sediment Quality Guideline (ISQG) and US Environmental Protection Agency (USEPA) screening benchmark value. Pb exceeded Canadian ISQG value but tallies with USEPA benchmark value. Pearson's correlation exhibited significant correlation (p < 0.01) of molybdenum (Mo) with copper (Cu) and Pb; Cu with Pb, vanadium (V), and Ba; V with Cu, Pb, iron (Fe), Ba, and beryllium (Be); and Fe with Be and V. Principal component (PC 1) consists of Pb, Mo, cobalt (Co), Cu, arsenic (As), Cr, V, and nickel (Ni) and showed significant correlation. Geo accumulation index (I-geo) values for Mo, Cu, V, Pb, Zn, Ni, Co, Mn, and Ba fall under unpolluted (0) to moderately polluted (1–2) classes. Maximum enrichment factor (EF) values show extremely high and significant enrichment of Ba and Pb in few locations. Co, Cr, Cu, Mn, and Zn possess maximum EF values classified as moderate enrichment. Ni, Mo, As, and V obtained maximum EF values classified as depleted to minimal enrichment. Modified pollution index (MPI) values showed high PTEs contamination in mostly cultivation locations. Single element potential ecological risk (EiR) mean values trend EiR (As) > EiR (Pb) > EiR (Co) > EiR (Cr) > EiR (Cu) > EiR (V) > EiR (Ni) > EiR (Zn). Comprehensive potential ecological risk (RI) shows medium risk "B" and strong risk "C" levels in few locations. The use of multiple pollution indices such as I-geo, EF, EiR, and RI in pollution assessment indicated similar trend of PTEs contamination of stream sediments. Levels of PTEs contamination are elevated in cultivation areas more than in granite quarrying and mining areas. This study serves as a benchmark for conducting suitable environmental management strategies to scientists in Nigeria and other parts of the world. [ABSTRACT FROM AUTHOR]

Natural (40K, 226Ra, 232Th, 238U) and anthropogenic (137Cs) radionuclides in consolidated sedimentary rocks (limestones s.l. and marls) and unconsolidated sediments (stream sediments and soils) of the Kaštela Bay (Adriatic Sea, Croatia) coastal area were studied. Kaštela Bay is a typical karstic environment and it is under strong anthropogenic influence due to industrialisation and urbanisation. Relationships between radionuclides, their behaviour in different types of samples and possible influencing factors were studied. Radionuclides were also studied in relation to selected metals (Al, K, Ca, Fe, Ti, Mn, V, Cr, Co, Ni, Cu, Zn, Ga, Rb, Sr, Y, Pb and As) and distribution in limestones s.l., marls, stream sediments and soils. Radionuclides' massic activities were determined by gamma-spectrometry and metal mass fractions were measured by EDXRF technique. Relationships were studied using statistical tools (principal component analysis, factor analysis). It was found that stream sediments were more similar to source rocks (limestones s.l. and marl) than to soils in terms of natural radionuclides' activities. 40K and 232Th in consolidated rocks were preferentially bound to alumosilicates and associated with the majority of studied metals. However, this was not the case with 226Ra and 238U, which did not show any preferences regarding binding to mineral components or associating with metals. On the other hand, all four natural radionuclides presented the same behaviour in unconsolidated sediments, i.e. they were all preferentially bound to alumosilicates and associated with the majority of metals. 137Cs did not associate with any of the metals or other radionuclides in sediments. The statistical approach applied in this study revealed differences in radionuclides' relationships and behaviour in a karstic environment and implied possible influencing processes or factors. This approach can be applied in other types of environments as well to study preferential radionuclides' binding to certain mineral components that influences radionuclides' mobility and transport to other environmental compartments. [ABSTRACT FROM AUTHOR]

The paper presents the environmental impact of artisanal gold mining activities on the waters and sediments around Meli, northwestern Tigray, Ethiopia. Stream sediment, water, and tailing samples were collected in the dry season in January of 2019 and analyzed for heavy metals Cu, Zn, Pb, and As. The physicochemical parameters (pH, EC, major cations, and anions) of a few water samples were also measured. Flame atomic absorption spectrometry was used to determine the level of the metals in stream sediments. The results show that tailing has the highest concentration of metals followed by the stream sediments. The least concentrations are recorded in water for all metals. Pb has the highest mean concentration of all heavy metals in stream sediments, waters, and tailing samples. The mean Geo-accumulation Index (Igeo) and Contamination Factor (CF) suggest that the sediment represents uncontaminated to moderately contaminated classes. Concentrations of Cu and Zn in the water samples are generally within the maximum allowable concentration of the WHO, whereas concentrations of Pb and As are above the limit. Metal Index for surface and groundwater suggests that the area is polluted with heavy metals Pb and As. The main sources of the metals are assumed to be the sulfide ores facilitated by natural weathering processes and artisanal mining activities like excavations, crushing, grinding, and amalgamation processes. The Gibbs and Durov plots show that major hydrogeochemical processes controlling the water chemistry are water-rock interactions with considerable mixing of water types. [ABSTRACT FROM AUTHOR]

This study serves the purpose of generating a geochemical Fe-bearing potential map. Stream sediment geochemical survey was employed by collecting 843 samples for analyzing 19 elements and oxides. Taking preprocessing of data (e.g. outlier correction and data normalization) into consideration, a Concentration-Number (C-N) fractal model was used to separate different geochemical populations of Fe2O3, TiO2, V, and the main multi-element factor in close spatial association with the Fe targeting. A prediction-area(P-A) plot was drawn for each variable to determine the weight of each geochemical indicator. Results indicate that the main geochemical factor with an ore prediction rate of 73%, has occupied 27% of the Esfordi area as favorable zones for further mining prospectivity. The Esfordias a favorable Fe-bearing zone is of special interest in the NE of the Bafq mining district that hosts important "Kiruna-type" Magnetite-Apatite deposits. In addition, a synthesized indicators map was prepared by implementing a data-driven multi-class index overlay in a similar fashion to the previous version of the method, upon which geochemical potential zones were mostly in the NE part of the Esfordi, intimately linked with intense fault density map. The significance of this study lies in localizing the most geochemical favorable zones through simultaneous consideration of the C-N and PA plots accompanied by the incorporation of known active mines and prospects to determine indicator weight. Of note is that the Mineral Potential Mapping(MPM) has higher efficiency over each geochemical indicator with an ore prediction rate of 78% and area occupation of 22%. [ABSTRACT FROM AUTHOR]

Texture, mineralogy, heavy minerals, and major and trace elements, including REE, from surface sediment samples collected along the Nyong River (NR) were analyzed in the current study to characterize and discuss the intensity of weathering, provenance, and tectonic settings of the source area and estimate the chemical features that reflect the parental rocks, known from literature. The sediments are mainly fine- and coarse-grained sands, and the mineralogy is predominantly composed of quartz, accompanied by kaolinite, illite, opaque oxides, kyanite, rutile, zircon, tourmaline, sillimanite, garnet, and hypersthene. Geochemically, the sediments are classified as Fe–shale, Fe–sand, and quartz arenite. The CIA, PIA, CIW, and the A–CN–K and (A–K)–C–N plots indicate the high intensity of chemical weathering. The values of SiO2/Al2O3, Al2O3/Na2O, K2O/Na2O, ICV, and the ZTR index indicate the maturity of many samples. Most of the sediment samples experienced recycling, as revealed by the Al2O3–TiO2–Zr plot. Several bivariate plots such as Zr vs TiO2 and Th/Co vs La/Sc, and the REE pattern and size of Eu, indicate derivation from a source area composed mostly of intermediate and felsic rocks and, in a lesser extent, of mafic source rocks. Tectonic discriminant diagrams based on major and trace elements indicate rift and passive margin settings, which is consistent with several tectonic history models of the Ntem complex and the Pan-African belt. [ABSTRACT FROM AUTHOR]

Currently, the metals of Rare Earth Elements (REEs) have become very critical to various modern technologies ranging from cell phones and televisions to LED light bulbs and wind turbines. This work was carried out as the Pakistani contribution to the National-scale Geochemical Survey of South and Central Asia (NGSSCA) project. The objective of this study was to document and study the amounts and distribution of REEs in stream sediment of Pakistan, where such national-scale geochemical mapping was launched for the first time. A total of 4277 regular and 168 duplicate samples were collected, encompassing approximately 360,000 km2 of Pakistani outcrop regions. The findings from the geochemical analysis of stream sediment in Pakistan revealed a spectrum in the total Rare Earth Elements (ΣREE) concentration, spanning from 10.22 mg/kg to 1403.1 mg/kg, averaging at 132.5 mg/kg. LREEs are relatively enriched compared to HREEs with an average of LREEs/HREEs of 3.08. The distribution patterns of REEs in stream sediment are demonstrated. It's has been concluded that high concentrations of REEs are mainly distributed in the Himalayan fold and thrust belt, the Karakoram terrane and the Kohistan island arc in the northern part of Pakistan. The bedrock mineralogy and lithology significantly affect the distribution patterns of REEs in stream sediments. The national geochemical mapping of Pakistan provides a useful method for locating alkaline igneous rocks and identifying potential REE mineralization. • The first National-scale Geochemical Mapping in Pakistan was launched. • The bedrock mineralogy and lithology affect the distribution of REEs in stream sediments. • Some new target areas/belts for the REE mineralization are predicted. [ABSTRACT FROM AUTHOR]

BACKGROUND In the multi-target regional geochemi-cal survey project, sulfur is one of the analyzed elements. During measurement of samples with a high-frequency infrared carbon-sulfur analyzer, different factors include the blank of the crucible, water vapor in the pipeline, different sample weights, sample and flux stacking order, and different flux additions, which would result in poor reproducibility of sulfur and even a negative value. OBJECTIVES To eliminate factors that affect the repeatability of sulfur analysis and improve the accuracy of sulfur analysis. METHODS The conditions for determination of sulfur in soil-stream sediments were optimized by comparing the sample weight, sample and flux stacking order, and flux amount. RESULTS In the case of reducing the blank value of the crucible and strictly controlling the humidity in the trachea of the instrument, the calibration curve shows a good relationship (r ≥ 0.9990) after the sample was analyzed by mixing 0.08g sample, 0.5g iron and 1.0g tungsten. After analyzing the different results using a calibration curve of the appropriate concentration, the logarithmic differences of the sulfur analysis results are -0.036-0.062 and the relative standard deviations (RSDs) are 7.13%-9.93%. CONCLUSIONS Both the logarithmic difference and the standard deviation meet the requirement of multi-target regional geochemical survey (1:2500000), indicating that the analytical results of this method are accurate and reproducible.