Zn Values Research Articles

Assessment of plant ecological variability and heavy metal accumulation potential in naturally growing plant species of Pakhar bauxite mine site, Jharkhand, India

Abandoned bauxite mine (ABM) soil generally contains an unacceptable number of heavy metals (HMs), causing several ecological and environmental issues. The present study was conducted with a similar objective to assess the HM accumulation potential of the naturally growing plant species from Pakhar ABM site. Vegetation communities were studied using quadrat methods for plant species at both ABM and the control site (near the ABM site). A total of 21 (9 at the ABM site and 12 at the control site) plant species were recorded in the present study belonging to 10 families. Vegetation study revealed that the dominant plant species were Ammophila arenaria and Lantana camara at ABM site and Lantana camara at the control site. The concentration of HMs in soil at the ABM site, were 66180.00 mg kg−1 Al, 62.20 mg kg−1 Cr, 22.60 mg kg−1 Cu, 346800.00 mg kg−1 Fe, 780.80 mg kg−1 Mn, and 39.80 mg kg−1 Zn while in the soil of site located nearby taken as the control showed 56500.00 mg kg−1 Al, 4.40 mg kg−1 Cu, 51120.00 mg kg−1 Fe, 58.20 mg kg−1 Mn, 13.00 mg kg−1 Zn. Ammophila arenaria, Miscanthus sinensis, Acacia drepanolobium and Rumex pulcher exhibited the highest metal accumulation at the ABM site, while Ocimum campechianum, Lantana camara, Panicum virgatum L., Euphorbia hirta and Holcus lanatus, Cerastium glomeratum thuill and Shorea robusta exhibited the highest metal accumulation at control site. Plant Lantana camara showed considerable TF values for Pb, Al and Fe, from the ABM soil while Shorea robusta showed high TF values for Al, Cu, Zn, and Fe from the control soil. The BAF for Cu, Mn and Zn from ABM soil were observed in Acacia drepanolobium whereas Cerastium glomeratum thuill exhibited maximum BAF values for Zn and Cu from control soil.

Participation of small mammals in the biogenic transit of trace elements under chemical pollution of the environment

The participation of small mammals (SM) in the migration of essential (Cu, Zn) and toxic (Cd, Pb) trace elements (TEs) in forest ecosystems under conditions of severe industrial pollution of the environment (1990–2000) by a large copper smelter (Middle Urals, Russia) and after a significant reduction in its emissions (2010–2019) was considered. The peculiarity of transit food flows (TFF) in the pollution gradient was determined by the composition and abundance of animals of different trophic groups (phytophages, mixophages, zoophages), as well as the specifics of their diet. The reduction in emissions was accompanied by positive changes in the SM communities, expressed in an increase in the number and structural rearrangements of trophic groups (TG), which led to partial changes in the composition and amount of food consumed, as well as the content of TEs in them. By the end of the observation period in the background zone, the animal-controlled TFF remained stable for most TEs (Cu, Zn, Cd), for Pb it decreased by a factor of 2, but not as a result of reduced emissions. In contaminated areas, the value of TFF Zn has not changed, Cd has increased, Cu and Pb - decreased. It was concluded that in the taiga zone the main contribution to the dynamics of biogenic TEs flows over time and space was made by a group of mixophages that dominated the pollution gradient.

Restoring soil nutrient stocks using local inputs, tillage and sorghum-green gram intercropping strategies for drylands in Eastern Kenya

Soil macronutrient and micronutrient availability is particularly critical in semi-arid agro-ecological zones that are characterized by poor soil fertility and low rainfall regimes. An experiment was initiated in Siakago, Embu County to investigate the effects of tied-ridges, conventional tillage and input applications on soil nutrient fertility using a randomized complete block design with a split-split plot arrangement for 4 seasons (2018–2021). The treatments comprised of two main plot tillage systems, three cropping systems allocated to the sub-plots and four soil input management treatments assigned to sub-sub plots. ANOVA was used to test the effects of different treatments including tillage, crop system and soil fertility management using Genstat software. The data was also subjected to Principal Component Analysis procedures using R ("FactoMineR" and "factoextra") to examine the inter-relationship patterns between different soil fertility parameters and to reduce the data into independent soil fertility components. There were significant main effects due to crop system (Soil Mn), tillage and crop system interaction (SOC and TSN) and soil fertility management (TOC, TSN, Ca, Zn). Soil inputs significantly influenced soil carbon concentrations (p = 0.002), with the lowest values observed in the control (0.2 %), followed by sole fertilizer (0.35 %), manure + fertilizer (0.41 %) and the fully decomposed manure treatment (0.61 %). The soil-extracted manganese values recorded significant effects due to crop system, while soil-extracted Zn values were significant due to soil fertility management. Multivariate analysis results revealed the structure of soil nutrient distribution. Tied ridging can improve soil micronutrient availability through reduced soil erosion, conservation of soil organic matter, which can improve soil micronutrient availability. Soil conservation practices such as tied-ridging integrated with organic input applications can enhance multiple nutrient availability for improved crop performance and human nutrition in dryland farming systems where farmers lack soil moisture, technologies and resources to enhance crop nutrient availability.

Accumulation and contamination of gully pot sediments from varied land-use types: metal loads, concentrations and speciation

Urban stormwater typically enters sewer networks through gully pots, which allow a primary sedimentation of solids upstream of the piped network. The regular removal and disposal of retained sediment are necessary, costly and can involve environmental risks due to the contamination of sediments with substances from the urban environment such as metals. The concentrations and speciation of Cd, Cr, Cu, Ni, Pb and Zn were analysed in sediments from 26 gully pots located in different land use areas in Stockholm, Sweden. In addition, accumulation rates of both sediment and metal masses were evaluated, providing a basis for optimising maintenance practices and better understanding of impacts of characteristic urban land use types. Metal concentrations varied by at most a factor of eight between samples and were always below Swedish polluted site guidelines for less sensitive land use, with only eight samples exceeding the guideline values for Cu and Zn for sensitive land use. Sequential extraction showed Pb and Zn to be the most mobile metals. Sediment accumulation rates varied from 0.003 to 0.197 kg/m2 impermeable surface/year. Metal accumulation rates were much more variable than metal concentrations, with a factor of up to 172 between the highest and lowest rates and the highest metal accumulation rates corresponding to the lower range of mass loads in road runoff. Differences in metal concentrations, sediment or metal mass accumulations could not be solely attributed to either traffic or catchment land use. In contrast, traction grit used for winter road maintenance, which has low (but detectable) metal concentrations, is identified as a major component of gully pot sediments, with a combined effect of both moderating metal concentrations and contributing to total mass.

Remediation of acid mine drainage and immobilization of rare earth elements: Comparison between natural and residual alkaline materials

Acid mine drainage (AMD) is a well-known source of toxic trace metals in freshwaters. Traditional passive treatment systems rely on AMD neutralization with limestone and removal of most common toxic transition metals such as Cu and Zn with little attention to rare earth elements (REE). Alkaline waste materials now receive increasing attention as low cost AMD treatment alternatives in the circular economy. This study was set up to identify the efficiency of alkaline waste materials remediating AMD and scavenging REE in addition to other toxic trace elements. An AMD sample was collected from a lixiviate coming from pyrite heaps in the Iberian Pyrite Belt (pH = 1.8, 30 μM ∑REY). The sample was treated with either blast furnace slag (BFS) generated during smelting of iron ore in a blast furnace or biomass ashes (BA) derived from combustion of biomass, thereby using analytical grade CaCO3, and NaOH as reference products. The batch alkalinization experiments were conducted by adding each alkaline material at an amount to obtain an equal pH to ≈6.5. The required amounts of the products were NaOH < CaCO3<BFS < BA in line with their acid neutralizing capacities. The largest removal of sulfate from water was obtained in the CaCO3 treatment suggesting gypsum precipitation which was lower with BA and BFS and virtually absent with NaOH, these trends were confirmed by SEM-EDX and XRD. Both BFS and BA removed more Fe than CaCO3 and NaOH. The REE elements were well removed by all treatments (>99%) and the remaining REE concentrations in the solutions were clearly lower than values for Cu and Zn. The Zn and Cu removals were not consistently high enough (except with NaOH) to meet environmental limits in the discharge waters. The largest efficiency for REE removals was obtained with CaCO3. Indirect evidence here suggests that gypsum is a better host for the trivalent REE than Fe(III) minerals in the precipitates. The ionic radii of trivalent REE are more similar to Ca2+ than to Fe3+, explaining the better potential of gypsum as REE host. This study showed also the potential of BFS as alkaline agent for the remediation of AMD in terms of its higher alkalinity generation potential as compared to BA, thus making BA less promising than BFS.

Heavy metals pollution and potential ecological risk assessment in farmland soils from typical mining area: a case study

ABSTRACT The research aimed to investigate HMS, utilizing the Pearson correlation coefficient for speciation distribution analysis, PCA for assessing pollution characteristics and identifying sources, the Muller index to evaluate ecological risk level, and the Hakanson potential ecological risk index to determine the order of risk from heavy metals. The topsoil near SA was collected, and the contents of seven kinds of HMS, As, Cd, Pb, Zn, Ni, Cu and Cr were determined, so as to evaluate the types of high-risk heavy metal pollution further accurately. The research recorded valuable data showing that the concentration values of all seven HMS in the investigated area exceeded prescribed agricultural soil contamination limits. The concentrations of As, Cd, and Pb were found to be 8.30, 46.20, and 6.08 times higher than the screening values in Hunan Province, respectively. In the GYB sampling area, the coefficient of variation (CV) values for Cu, Pb, As, Zn, and Cd are all between 0.50 and 1.00. Notably, the CV value for Cd reaches 0.82, indicating a significant variation. Significant correlations were found between Cd and Zn (Cd-Zn), Pb and Zn (Pb-Zn), Ni and Cr (Ni-Cr) in the tested soils. The ecological risk index () results showed that Cd was the primary pollutant in the study area, with the potential ecological hazards in the tested soils ranked as Cd>As>Pb>Cu>Zn>Ni>Cr. Combining both evaluation methods, the study area’s potential ecological risk order is SZY>GYB>CTL.

Valuation of theoretical and experimental thresholds fluences of pure metals using laser induced plasma spectroscopy (LIPS)

The present studies demonstrate the valuation of threshold fluence of pure metals using the laser-induced plasma spectroscopy technique. The optical emission spectra of the s, p, and d-block elements including Li, Mg, Sr, Ba, Al, Sn, Pb, Cu, Zn, Au, Cd, and Ag were recorded using a Q-switched Nd:YAG laser operating at 532 nm and an Echelle spectrograph (Andor Mechelle M500) equipped with a gated ICCD system. The laser fluence was varied from 0.5 to 15 J cm−2 using a fixed spot size of approximately 1.0 ± 0.1 mm. The threshold fluence was measured using the isolated and well-separated emission lines of all the elements. The experimental threshold fluence values for Li, Ca, Mg, Sr, Ba, Al, Sn, Pb, Cu, Zn, Au, Cd, and Ag were determined as 0.8 J cm−2, 1.4 J cm−2, 1.18 J cm−2, 0.7 J cm−2, 0.4 J cm−2, 2.5 J cm−2, 1.0 J cm−2, 0.7 J cm−2, 3.15 J cm−2, 3.9 J cm−2, 0.8 J cm−2, 3.4 J cm−2, and 0.8 J cm−2 respectively. Theoretical values of the threshold fluences were also determined, showing good agreement with the experimentally measured values.

Development and application of novel risk indices for assessing heavy metal pollution in aquatic sediments

This study presents the development of a new sediment individual risk index (SIRI) and sediment complex risk index (SCRI) to assess heavy metal pollution in Anzali Wetland sediments. SIRI incorporates total metal concentrations, bioavailability, and sediment quality guidelines. SCRI, derived through principal component analysis (PCA), integrates SIRI for a comprehensive risk assessment. The newly developed indices were systematically classified. Results showed varying risk levels with SIRI values of Zn, Cr, Cu, Pb, Ni, As, Cd, and Hg as 0.82, 1.32, 0.98, 0.71, 1.41, 1.37, 0.79, and 0.79, respectively. Pb, Cd, and Hg posed very low risk, Cu and Zn posed low risk, and Cr, Ni, and As posed moderate risk. SCRI yielded an index value of 1.02, indicating a moderate level of risk for the studied stations. Pearson correlation analysis validated SCRI with a highly significant and strong correlation coefficient (0.923) with metal bioavailability, serving as a risk indicator.

Heavy metals contamination, receptor model-based sources identification, sources-specific ecological and health risks in road dust of a highly developed city.

The present study quantified Ni, Cu, Cr, Pb, Cd, As, Zn, and Fe levels in road dust collected from a variety of sites in Tangail, Bangladesh. The goal of this study was to use a matrix factorization model to identify the specific origin of these components and to evaluate the ecological and health hazards associated with each potential origin. The inductively coupled plasma mass spectrometry was used to determine the concentrations of Cu, Ni, Cr, Pb, As, Zn, Cd, and Fe. The average concentrations of these elements were found to be 30.77 ± 8.80, 25.17 ± 6.78, 39.49 ± 12.53, 28.74 ± 7.84, 1.90 ± 0.79, 158.30 ± 28.25, 2.42 ± 0.69, and 18,185.53 ± 4215.61 mg/kg, respectively. Compared to the top continental crust, the mean values of Cu, Pb, Zn, and Cd were 1.09, 1.69, 2.36, and 26.88 times higher, respectively. According to the Nemerow integrated pollution index (NIPI), pollution load index (PLI), Nemerow integrated risk index (NIRI), and potential ecological risk (PER), 84%, 42%, 30%, and 16% of sampling areas, respectively, which possessed severe contamination. PMF model revealed that Cu (43%), Fe (69.3%), and Cd (69.2%) were mainly released from mixed sources, natural sources, and traffic emission, respectively. Traffic emission posed high and moderate risks for modified NIRI and potential ecological risks. The calculated PMF model-based health hazards indicated that the cancer risk value for traffic emission, natural, and mixed sources had been greater than (1.0E-04), indicating probable cancer risks and that traffic emission posed 38% risk to adult males where 37% for both adult females and children.

Characteristics and Potential Ecological Risks of Heavy Metal Content in the Soil of a Plateau Alpine Mining Area in the Qilian Mountains

In recent years, the ecological and environmental problems caused by mining in the Qilian Mountains have attracted considerable attention, and the government has carried out a number of comprehensive ecological environment remediation projects there, among which ecological restoration in the Qilian Mountain alpine mining area is an essential task. As a result, heavy metals have been studied in the soil of the Qilian Mountain alpine mining area. This can provide a scientific basis and data support for the establishment of a demonstration index for monitoring ecological environmental restoration in mining areas. In order to understand the content and contamination status of heavy metals in the soil surrounding the alpine mining area of Qilian Mountain, 56 soil samples were collected to determine the levels of eight heavy metals, including Cd, Hg, As, Pb, Cr, Cu, Zn, and Ni. The spatial distribution of heavy metals in the soil of the study area was analyzed based on a statistical approach. The single-factor pollution index (Pi), Nemerow comprehensive pollution index (PN), geoaccumulation index (Igeo), and potential ecological risk index (RI) were used to evaluate soil heavy metal pollution and potential ecological risk. Principal component analysis (PCA), positive matrix factorization (PMF) models, and geostatistical analysis were also used to investigate the source of heavy metals. The results show that the average Cd, As, Cr, Cu, Zn, and Ni content of the grassland soil around the mining area exceeds the soil background values in both Qinghai Lake Basin and Qinghai Province. The spatial distribution of the eight heavy metal elements in soil showed an island-like pattern, with high-value areas of each metal element appearing, indicating that human activities in the study area had negative effects on the soil environment. The value of the single pollution index showed that levels of Ni, Cd, Cu, Cr, Hg, and As pollution were low, while there was no Pb or Zn pollution. The Nemerow integrated pollution index had an average value of 1.39, indicating a slight pollution trend. The average values of Cr and Zn in the geoaccumulation index ranged from 0 to 1, indicating mild to moderate contamination in the studied region. The average value of the integrated ecological risk index in the study area was 135.43, which is in the intermediate ecological risk range. In descending order of size, the average ecological risk index of each heavy metal element was Hg &gt; Cd&gt; As &gt; Ni &gt; Cu &gt; Pb &gt; Cr &gt; Zn. From the perspective of the spatial distribution pattern of ecological risk, the two high-value discriminants were in the western part of the study area, close to the mining area. Zn, Cu, Pb, and Cd in soils were mainly affected by human activity, while Cr and Ni were mainly affected by soil geochemistry. Cd is the main contaminant in the study area, and soil Cd contamination of the grassland in the study area must be considered.

Assessment of industrial effluents for heavy metals concentration and evaluation of grass (Phalaris minor) as a pollution indicator

This study was conducted to investigate the impact of industrial activities on heavy metals status in wastewater, sludge and flora on the bank of selected main drains of the Hayatabad Industrial estate, Peshawar. Plants, sludge and wastewater samples of selected sites were collected and analyzed for heavy metals distribution; cadmium (Cd), chromium (Cr), lead (Pb) and zinc (Zn) levels. Bioconcentration factor (BCF) values were calculated for plants (Phalaris minor) grass species found naturally at all sites. The results showed that the levels of metals in wastewater were lower than permissible limits except Cd and the concentration of metals in plants and sludge were within permissible limits when compared to their respective standards. Metal distribution was in the following order; sludge > plants > wastewater and the concentration of metals varied according to the distance from the source with no specific pattern. Sludge samples for all sites showed a high concentration of metals as compared to plants and wastewater samples. In grass samples, Zn was highest and Cd was low for all sites. Metals accumulation in plants was in order of; roots > shoot. Pearson's coefficient correlation showed that Cr in plant roots and Zn in shoots showed significantly high correlation with Cd in sludge while Pb in roots showed significant negative correlation with Zn in sludge. BCF values for Cr, Pb and Zn were >1, showing the phytoremediation potential of plants.

Perspectives on the use of biochar in the valorization of mining wastes from sulfide minerals flotation: Recovery of metals and effects on toxicity

This study aims to evaluate the use of two biochars obtained by pyrolysis of sugarcane-bagasse and compare it with commercial activated carbons as catalysts for the recovery of metals from one mining waste from sulfide minerals flotation (MW). It is also intended to determine the influence of carbon materials on the toxicity of the final residues. Leaching tests were performed in 250 mL erlenmeyer flasks using plates with magnetic stirrers during 24 h, at 90 °C and a stirring speed of 350 rpm. For each test, 5 g of MW were mixed with carbon material in two ratios of MW/carbon material (1/0.1 and 1/0.2 wt/wt) and 100 mL of leaching agent (H2SO4 solution at pH = 0.8–0.9 and 5 gL−1 of Fe3+). The experimental results showed that the addition of biochar and activated carbon enhances the recovery of Cu and Zn. The use of commercial activated carbons in ratios of 1/0.1 and 1/0.2 MW/carbon material leads to the extraction of more than 91 % of Cu and 97 % of Zn, after 24 h of leaching. For biochars, the highest recovery values of Cu (82.9 %) and Zn (98.1 %) were achieved with biochar prepared at 750 °C and used in the ratio of 1/0.2. However, the addition of carbon materials does not improve the recovery of Co. The presence of carbon materials decreased the electrical conductivity and pH of the final residue. The leaching of samples MW + W35 (1/0.1) and MW + BC550 (1/0.1) leads to a germination index higher than 90 %. For two biochars, all samples showed non-phytotoxicity.

Development of a certified reference material for accurate determination of the leaching of Pb and Zn in solid waste.

Certified reference materials (CRMs) with high accuracy and traceability play a significant role in the calibration of equipment and validation of analytical methods. However, there is still a lack of suitable solid waste CRMs for quality assurance and quality control. Thus, a CRM (GBW(E)085538) was developed for accurate determination and reliable measurement of the leaching of Pb and Zn in solid waste according to the requirements of ISO 17034 and the recommendations of ISO Guide 35. This study describes the steps performed for the development of the CRM. These steps include material preparation, homogeneity, and stability during transport and storage, assignment of certified values, and their uncertainties. The material was dried, ground, sieved and well-mixed, and the final bulk material was bottled in 1kg portions. Analytical techniques like inductively coupled plasma-mass spectrometry (ICP-MS), inductively coupled plasma-optical emission spectrometry (ICP-OES), and flame atomic absorption spectrometry (AAS) have been used for the characterization of property values. Concurrently, an inter-laboratory comparison study involving 9 qualified laboratories was implemented to support the certification study. The certified values of Pb and Zn were (4.66 ± 0.21) mg/L and (2.95 ± 0.14) mg/L with 7-month stability.

Pollution Characteristics, Source Analysis, and Risk Assessment of Heavy Metals in the Surrounding Farmlands of Manganese Mining Area

In order to understand the status of heavy metal pollution and the resulting ecological risk of farmland soil surrounding the manganese mining area, 174 soil samples were collected, and the heavy metals(Cu, Zn, Pb, Cr, Ni, Mn, As, and Hg) were analyzed. Principal component analysis (PCA) and the positive matrix factorization (PMF) model were used to determine the source of heavy metals in the soils. The single-factor pollution index method, geo-accumulation index method, potential ecological risk assessment method, and US EPA health risk assessment model were used to evaluate the ecological environment risk of heavy metals. The results showed that the average values of Cu, Zn, Cr, Ni, Mn, and Hg exceeded the background value of Guizhou. 100% of Zn samples and 38.86% of Cu samples exceeded the risk screening value for agricultural land soil pollution. Source analysis revealed that the main sources of soil heavy metals were mining emission, mixed agricultural activity and transportation, nature, and agricultural activities. The risk evaluation showed that Ni, Cr, Pb, and As belonged to the clean level, Hg and Cu were in a light pollution stage, Zn fell into the category of moderate contamination, and Mn reached the heavy pollution level. Cu, Zn, Pb, Cr, Ni, Mn, As, and Cd posed low potential ecological risk, while Hg caused a considerable potential ecological risk. In total, the integrated potential ecological risk of heavy metals was ranked "strong", eight types of heavy metals had carcinogenic risks and non-carcinogenic risks for children aged 0-5 years, and the main contributing factors were Cr and Mn, respectively.

Water quality and health risk assessment in the Gandaki river basin, central Himalaya, Nepal

Public health is at threat due to chemical contaminants in drinking water which may have direct health concerns. The suitability of water for health is primarily governed by the mineral constituents present in the water. The present study was carried out to evaluate the water quality and associated health risks in the Gandaki River Basin (GRB) in Central Himalaya, Nepal considering hydrochemical variables such as total dissolved solids (TDS); major cations (Ca2+, Mg2+, K+, and Na+); major anions (Cl-, NO3-, SO42-, and HCO3-) and trace metals (As, Cu, Mn, Ni, Pb, Zn, Ba, Cr, Li and Sr) in spatiotemporal levels. Water Quality Index (WQI), Health Risk Assessment (HRA), and Cancer Index (CI) were analyzed to evaluate the overall quality of water in the GRB. The results revealed that all the examined variables were within the National Guidelines recommended for domestic uses. Moreover, the results revealed that concentrations of TDS, major ions, and trace metals showed significant seasonality and the WQI values were found to be 36.38, 23.77, and 30.36 in pre-monsoon, monsoon, and post-monsoon, respectively indicating better water quality in the monsoon season. Additionally, CI analysis of the selected trace metals such as As, Cr and Pb indicated relatively low cancer risk in the river water during all the seasons. The hazard quotient (HQ) dermal values of all the elements were &lt; 1, signifying the little or no adverse effects via a dermal path, while HQ ingestion values of Ba, Li, Sr, and Zn were found to be &gt;1 during all the seasons indicating their possible threat via ingestion path. This study provides a useful database and suggests regular assessment and, also appropriate policy formulations for safeguarding the water bodies in the Himalayas.

Ecological risk evaluation and sensitivity analysis of heavy metals on soil organisms under human activities in the Tibet Plateau, China.

The Tibetan Plateau (TP), once considered a pristine environment, is now facing increased heavy metal pollution due to human activities, causing unprecedented ecological risks to soil organisms. However, little is known about the sensitivity and tolerance of different soil organisms to heavy metal toxicity in the high-altitude areas of the TP under the background of human activity intensity and future risk control priorities. In this study, we conducted an ecological risk assessment and threshold calculation for 10 heavy metals in soil for typical soil organisms, including Cd, Co, Cr, Cu, Ni, Pb, Zn, Mn, Sb, and Sn, using the species sensitivity distribution (SSD) method in the zone between Ranwu town and Renlongba glacier on the TP. The results revealed that most sampling sites had average levels of Cd, Sb and Ni exceeding their regional soil environmental background values and were the major contaminants. Impressively, the hitherto undeveloped Renlungba Glacier showed relatively high contamination levels of Sb and Ni. From the view of sensitivity differences, the toxicity risks of Cd, Cr, Cu, Ni and Pb were higher for terrestrial plants than for soil invertebrates based on the fitted heavy metal SSD curve trends. In terms of the ecological risk level, the average potentially affected fraction values of Zn and Ni reached 18.5% and 17.0%, respectively, with significant ecological risk at a few sampling sites. In terms of ecological risk thresholds, the Cd concentration at the 5% hazard concentration (HC5) control level was 0.05 mg/kg, which was the heavy metal with the highest risk in this study. Comparing the HC5 values of each heavy metal with the limit values in the current Chinese soil environmental quality standards, the existing administrative policies as a whole lack a powerful prevention of the potential ecological risk posed by heavy metals to soil organisms.

Evaluation of Heavy Metal Pollution in Rice (Oryza sativa L.) Fields of Bafra Plain

Heavy metals are naturally present in the soils in trace quantity. Besides, some soils include these elements at high levels resulting from the weathering of minerals or human activities. Contamination of these metals has been of great concern in the environment interrelatedly with their toxicity, persistence and non-degradability. So, this article aimed to evaluate heavy metal pollution by using several pollution indices contamination factor (CF), degree of contamination (CD), pollution load index (PLI), summarization of the sources of heavy metals, and change of these metals along soil depth. For this purpose, 10 coordinated soil samples were taken from 0-20 cm and 20-40 cm depths in the rice fields of Bafra Plain in Samsun-Türkiye. In these samples, some physico-chemical soil characteristics (texture, pH, electrical conductivity, organic matter and lime content, available phosphorus and cation exchange capacity) and heavy metal contents Zinc (Zn), copper (Cu), nickel (Ni), cobalt (Co), cadmium (Cd), chromium (Cr) and lead (Pb) were determined. According to the results, metal contents were determined between 39.79-58.44 mg kg-1, 32.15-68.31 mg kg-1, 75.68-132.6 mg kg-1, 11.95-18.02 mg kg-1, 0.001-0.278 mg kg-1, 61.88-102.5 mg kg-1, and 9.942-14.67 mg kg-1 for Zn, Cu, Ni, Co, Cd, Cr and Pb, respectively. While Cd content was higher at 0-20 cm depth, Cr, Ni and Zn values were higher at 20-40 cm. Cu, Pb and Co values did not show significant change with depth. Average CF values for heavy metals were determined as Ni&gt;Pb&gt;Cr&gt;Cu&gt;Cd&gt;Zn&gt;Co. Degree of contamination values varied between 4.922-7.848 and PLI values varied between 0.946-1.028. In all elements, CF and CD values were classified in the group of low and moderate contamination. Besides, significant relationships were found between soil physicochemical properties, heavy metal concentrations and pollution indices.

Assessing Human Health Risks in Asejire Lake: Implications for Water Resources in Industrialized Ibadan, Nigeria

Human health risk assessment of Asejire Lake in densely populated and industrialized Ibadan city has been examined using Average Daily Dose (ADD), Hazard Quotient (HQ), Hazard Index (HI), Chronic daily intake (CDI) and Carcinogenic Risk (CR) calculated from the hydrochemical analysis results of Aluminum, Barium, Chromium, Copper, Iron, Manganese, Nickel, Lead and Zinc. ICP-MS laboratory technique was used from which the results of the selected trace elements were extracted. The average values of Ba, Al, Cr, Fe, Cu, Mn, Pb, Ni and Zn are: 0.08ppm, 0.39ppm, 0.001ppm, 1.41ppm, 0.004ppm, 0.068ppm, 0.004ppm, 0.002ppm and 0.035ppm respectively which are all below prescribed standards except Al and Fe. The average values of TDS, EC and pH are: 51.73ppm, 100μS/cm and 7.4 respectively which show that the water is non-saline but slightly alkaline in nature. The average values of ADD, HQ, and HI for all age groups were generally &lt;1 falling within low chronic risk for HI. However, Values computed for children are close to unity and caution must be taken for children’s consumptions both in ingestion and derma absorption. Order of abundance of average CDI is: Fe&gt;Al&gt;Ba&gt;Mn&gt;Zn&gt;Pb&gt;Cu&gt;Ni&gt;Cr respectively. Average CR for Cr and Pb fall within 10-6 and 10-4 and above respectively and this gives a signal for cancer risk in consumption. Based on WHO background values, there are elevated values of average Contamination Factor (CF) above one for Al (2) and Fe (5) depicting some degrees of contamination in water phase and Degree of Contamination also ranged from 7 to 9 (average, 8) indicating low to moderate degree of contamination. Al and Fe sourced from the various anthropogenic and lithogenic activities contributed significantly to metal loading in the water which are of health significant.

High-precision zinc isotope measurement of chemically different geostandards by multicollector inductively coupled plasma mass spectrometry.

Zinc isotopes are becoming increasingly applicable in high-temperature geochemistry, for example in crust-mantle interaction and volatilization-related processes. The published zinc isotope data for some commonly used reference materials, however, show large interlaboratory offsets. In addition, there is still limited data for zinc isotope compositions of many widely used geological reference materials. For precise and accurate zinc isotopic ratio analysis of chemically diverse geostandards, including ultramafic to felsic igneous rocks, carbonatites, sediments and soils, an improved procedure for chemical purification of zinc was introduced in this study. The factors potentially affecting zinc isotopic ratio measurement were assessed. The accuracy and long-term reproducibility were obtained by measurements on both synthetic solutions and well-characterized geostandards. Purification of geologic samples with different zinc concentrations and matrix compositions yields consistent elution curves with nearly 100% recovery. Acidity and concentration mismatches and the presence of some matrix elements (e.g., Mg, Ti and Cr) have significant impacts on the precision and accuracy of zinc isotopic ratio measurement. The zinc isotope compositions of a suite of reference materials were measured using this method. The present study describes methods for the chemical purification of zinc and high-precision and accurate zinc isotopic ratio measurements using multicollector inductively coupled plasma mass spectrometer (MC-ICP-MS). The long-term external reproducibility for δ66 Zn values is ±0.04‰ (2SD). High-quality zinc isotope data of chemically different geostandards were reported to stimulate future interlaboratory calibrations.

Dielectric and electric properties of Zn doped and undoped Bi2/3Cu3Ti4O12 ceramic prepared by chemical route

Zn-doped and un-doped BCTO ceramics (Bi2/3Cu3−xZnxTi4O12, x = 0 and 0.05) were prepared by chemical route sintered at 1123 K for 8 h. The Phase formation of ceramics were confirmed by X-ray Diffraction. Their microstructural properties were examined through SEM, EDX, and TEM. The dielectric constant (ɛr) of BCTO ceramic was obtained higher than BCZTO-0.05 ceramics at 100 Hz and 470 K. The tangent loss (tan ) value for Zn doped BCTO ceramics were found to be lower than undoped BCTO ceramics at 10 kHz and 310 K. The conductivity dependence of Bi2/3Cu3−xZnxTi4O12 ceramics (where x = 0, 0.05), with the inverse of temperature follows the Arhenius equation, with a major temperature range of 300–500 K.