Levels Of Heavy Metal Contamination Research Articles

Heavy Metal Content in Hair at Workers in Gas Station of Sidoarjo City in 2021

One of the most dominant workplaces where heavy metal contamination occurs is the Gas Station (SPBU). Gas station workers are at high risk of being exposed to heavy metals while working due to inhaling fuel that evaporates into the air and vehicle fumes due to the behavior of motorists who do not turn off the engine while waiting in line. Determination of the level of heavy metal contamination of Zn, Cu, Pb, Cd, Fe, and Cr was determined through hair clippings using the Atomic Absorbtion Spectrophotometry (AAS) method. The gas stations used in this study are SPBU X and Y in Sidoarjo. This study aims to determine the levels of heavy metals in hair and to determine the relationship between working period, age, smoking habits, and savety with heavy metal levels in gas station workers in Sidoarjo. The type of research used is descriptive cross sectional and analytical method through filling out questionnaires and correlative statistics with SPSS. The results obtained showed that the average levels of heavy metals Zn, Cu, Pb, Cd, Fe, and Cr at SPBU X were 0.232, respectively; 0.000; 0.003; 0.001; 0.464; and 0.024 mg/g. while the average levels of heavy metals Zn, Cu, Pb, Cd, Fe, and Cr at SPBU Y were 0.516, respectively; 0.000; 0.007; -0.001; 0.345; and 0.051 mg/g. It can be said that the levels of heavy metals Zn, Cu, Pb, Cd, Fe, and Cr did not exceed the specified threshold. The results of the statistical test of the correlation between the levels of heavy metals Zn, Cu, Pb, Cd, Fe, and Cr with years of service, age, smoking habits, and PPE of gas station workers were not significant (p>0.05).

Evaluation of Heavy Metal Contamination in Surface and Ground Water in Maiganga, Gombe State, Nigeria

This study examines the levels of heavy metal contamination of farmland water from Maiganga Community in Akko local government area of Gombe state, Nigeria. Maiganga is a community famous for its deposit of coal which has attracted miners to the area. Water samples were collected from 10 different farming locations in the community. They were collected from Boreholes, Wells (groundwater) and Open water (surface water).

Distribution of heavy metals in sediments, physicochemical and microbial parameters of water from River Subin of Kumasi Metropolis in Ghana

The River Subin, which serves as a source of direct drinking water downstream, flows through the Metropolis of Kumasi in Ghana, making it vulnerable to pollution due to human activities. In this study, we assessed the heavy metals content in the sediment of the Subin River as well as the physicochemical properties and microbial load in the river. Water and sediments were sampled from Race course upstream and downstream, Asafo, and Abinkyi upstream and downstream, Kaase, Asokwa and Wood village with a sampling distance of 100 m. Index of Geoaccumulation (Igeo), contamination factor (CF), contamination degree (CD) and pollution load index (PLI) were used to assess the level of heavy metal enrichment and contamination in the sediments of River Subin. Analysis showed that temperature of the river ranged between 31.23 to 31.40 °C, pH ranged between 6.62 and 7.52, conductivity ranged between 1.16 and 4.67 µS/cm, total hardness ranged from 0.65 to 3.82 mg/L, Ca ranged from 0.26 to 1.22 mg/L, alkalinity ranged from 324 to 711 mg/L, Mg from 0.24 to 3.35 mg/L and Cl ranged from 56.76 to 99. 30 mg/L. The microbial load assessment indicated that the River Subin is highly polluted by E. coli, Faecal Enterococci, Total coliform and faecal coliform, which generally increased as the river flows downstream since more solid waste from domestic and industrial effluents enter the river. Igeo data suggested that the river was highly contaminated by Ag and Cd and moderately polluted by Pb and Co. The CF, CD and PLI, results showed high levels of Ag, Cd, Cr, Cu, Fe, Hg, Co, and Zn, indicating a progressive deterioration of water quality at the various sites. Our results suggest that the River Subin is highly polluted and thus, urgent management strategies are needed to mitigate further deterioration of the river.

Nutritional and Functional Properties of Wild Leafy Vegetables for Improving Food Security in Southern Angola

In Southern Angola, numerous non-woody forest products are sold at local markets, namely in Lubango (Huíla Province). Such is the case of herbaceous wild plants, locally known aslombi, which are sold fresh throughout the year and cooked as a vegetable. Although these wild leafy vegetables are commercialized and widely used in local food, there is still a lack of scientific knowledge about their properties. Thus, this study aimed to identify and characterize the species sold, and to determine their nutritional and functional properties. Our results revealed that three species—Amaranthus hybridus, Bidens pilosa, andGalinsoga parviflora—are usually sold at Lubango markets and consumed by local populations. These are annual exotic plants, native to Southern America, and usually occur spontaneously in croplands or disturbed areas, but can also be cultivated, particularlyA. hybridus. Physico-chemical analyses oflombispecies and mixtures sold at the markets included measurements of moisture, protein, lipid, and mineral content, as well as total phenolic content, antioxidant activity, and levels of heavy metal contaminants. The results revealed thatlombicontain a significant amount of protein (20–28 g/100 g, dry basis), high values of macronutrients and micronutrients, as well as of phenolic compounds (10–40 mg GAE/g) and a good antioxidant capacity. Given the availability oflombithroughout the year, our study demonstrated the importance of wild edible plants in Angola, both as a valuable natural resources and as a complementary food sources, as well as additional sources of income for many families.

Assessment of contamination level, pollution risk and source apportionment of heavy metals in the Halda River water, Bangladesh

This study demonstrates the level of heavy metal pollution in the Halda River, the only natural breeding source of carps in Bangladesh. Water was collected from 12 different sampling points along the Halda River. Water at various locations was found satisfactory in terms of the assessed physicochemical parameters (pH, electrical conductivity, and total dissolved solids). The presence of various cations and anions was also studied using ion chromatography. Atomic absorption spectroscopy was used to identify and quantify various heavy metals in the collected water samples. Among the heavy metals, Cd, Cr, Fe, Pb, Cu, and As concentration exceeded the safe limit suggested by WHO. The calculated heavy metal pollution index and metal index were found higher than the critical index value. The single-factor assessment (P i) and Nemerow's multi-factor index (P N) of heavy metals was calculated to find out the degree of pollution in the Halda River. The maximum values of P i (Cd), P i (Pb), P i (As), P i (Cu), and P i (Cr) were determined to be 26.67, 260.00, 17.00, 208.76 and 2.80 respectively. The maximum value of P N was found to be 289.04. The discharge of effluents from various large and small industries near the Halda River is considered to be the major source of the identified heavy metals. Multivariate statistical analysis such as principal component analysis, Pearson correlation matrix and cluster analysis revealed that most of the heavy metals originated from different anthropogenic sources. Multivariate analysis also showed that Co, Mn, Cu, Cr, Pb, Cd, NH4+, NO3- mainly came from artificial sources whereas Fe, Ca, As mainly originated from natural sources. Arsenic (As) also came from artificial sources with Cu.

Microbial and heavy metals examination of Expellers groundnut (Arachis hypogaea L.) oil

This study was designed to determine the microbial and heavy metal contamination level in expeller’s groundnut oil. Ten samples of groundnut oil were collected, labeled from E1 to E10 and the microbial and heavy metals examination tests were laboratory assessed. The study results showed that, the Total Count of Bacteria (TCB) for all oil Expellers samples was 33.8 Colony Forming Unit (Cfu)/ml oil. The highestt value was (111 Cfu/ml) in E10 and the lowest value (7 Cfu/ml oil) in E1. Concerning the Total Count of Fungal (TCF) for all samples was 31.4 and 6.75 Cfu/1ml for the yeast and mould respectively. Yeasts highest count was 109 Cfu/ml in E10 and the lowest count was 6 Cfu/ml in E1. while moulds highest count was 18 Cfu/ml in E10 and the lowest number of 2 Cfu/ml oil was found in E2. The bacterial detection test of Staph, Bacillus, Coliform, and E.Coli in the oils Expellers explored that no bacterial presence in E1, E3, and E7 but, the four types were recorded in E5, E9 and E10. On the other hand E2, E6 and E8 showed positive detection to Staph and Bacillus, while E4 was positive to Bacillus detection only. The Concentration of Iron (Fe) on expeller oil samples (E2, E3, E4, E6, E7, E8, E9 and E10) was higher than the minimum specification limit of 5meq/kg for heavy metals, but E1 and E5 were within the minimum specification limit. All expellers oil samples were higher than acceptable limit for Copper (Cu) concentration that established by SSMO and Codex alimentary for heavy metals of less than 0.1meq/kg. As well as, the Concentration value of Lead (Pb) all expeller oil samples were above the specification limit of heavy metals that should not be more than 0.1meq/kg.

Assessment of contamination of the estuarine area of the Northern Dvina River by calculating background concentrations (Fe, Mn, Zn, Cu, Cd, Pb, and Ni)

This publication is a continuation of research on the quantitation of the heavy metal contamination level (Fe, Mn, Zn, Cu, Cd, Pb, and Ni) in the ecosystem components of the estuarine area of the Northern Dvina River. To assess the contamination level with these metals in the ecosystem of the Northern Dvina estuarine area in the spot of the highest anthropogenic load (the area of Novodvinsk – Arkhangelsk – Severodvinsk urban agglomeration), we use the method of comparative analysis of the study object with the background plot – the river section above urban development. Using spatial mapping of the enrichment factor values for the aquatic ecosystem components, areas with abnormal excess of metal content in mollusc tissues, bottom sediments, and bottom water layer were determined. As established, the area adjacent to the city center and to an industrial zone on the left bank is subject to the highest anthropogenic load in the water area of the river delta top. The most likely sources of contamination with the considered heavy metals are the inflow of surface wastewater (meltwater and rain storm runoff), untreated municipal wastewater, and direct short-range atmospheric transport. The analysis of mollusc tissues proved to be a more informative and indicative approach to the assessment of the heavy metal contamination in water areas with complex hydrological and hydrochemical environmental gradients than the analysis of bottom water layer and bottom sediments.

Assessment of the metal contamination index in groundwater of the quaternary of the Middle Kert Basin, north‐eastern Morocco

AbstractThe purpose of this study is to highlight the quality of groundwater, with a special focus on the level of heavy metal contamination. To know the extent of this contamination, the protection and proper management of the groundwater resource is indispensable. The present work is in line with the metallic assessment of the water quality of the Oued Kert basin (Mediterranean area, Driouch province, eastern Morocco) by collecting 46 samples following ISO 5665 standard and tested pH, TDS, EC. Samples were analyzed for Heavy Metals with ICP‐MS and Flame Atomic Absorption Spectrometry (Pb, Cu, Hg, Al, Fe, Zn, Cr, Cd, and Ni) to detect heavy metal content. The interpretation of the analytical data, about the phenomena responsible for mineralization, was done using the hydro‐chemical classification, resulting from the integrated HPI approach, in addition to the statistical analysis of the data by the analysis of the main PCA components. The majority of the samples were found to be within limits, except for Fe, at some sampling locations, which is above the desirable limit, that is, 300 μg/L according to the Moroccan Drinking Water Standard. This indicates natural and anthropic effects. It shows that the groundwater to the northwest of the study area is probably affected by the leaching of heavy metals from the previous Mhajer mine.

Contamination level and risk assessment of heavy metals in the topsoil around cement factory: A case study

The cement industry is considered as a major source of heavy metals pollution in topsoil. This study aims at measuring the heavy metal contamination level in the vicinity of Shiraz cement factory, and assessing the ecological and environmental risks associated with the factory's activities in the surrounding topsoil. To do so, 10 samples of soil were taken from around the Shiraz cement factory at the depth of 0-10 cm and the concentration of some heavy metals including Al, Cd, Ni, and Pb was measured. Enrichment factor (EF), geo-accumulation (Igeo), and pollution load (PLI) indices were used to assess the ecological risk of heavy metals.Based on the results, the mean concentration of Al, Ni, Cd, and Pb was 6,937.14, 88.09, 1.96, and 30.74 mg/kg, respectively. The EF results showed that due to anthropogenic activities, the Ni, Pb, and Cd element has moderate, severe, and very severe enrichment in the study area, respectively. The Igeo result for Al, Ni, Pb, and Cd was -0.82, -0.17, 0.16, and 0.68, respectively, which indicates non- to slightly pollution of these heavy metals in this region. The mean PLI in the study area was 1.4 indicating the low to medium pollution of heavy metal. The results of this study can be useful in determining and investigating the environmental effects of Shiraz cement factory.

Sources, Mobility, Reactivity, and Remediation of Heavy Metal(loid) Pollution: A Review

Heavy metal(loid)s are a group of elements present commonly in the environment, including Cr, Ni, Cu, Zn, Cd, Hg, Pb, and As elements, among others. While these elements could have their origins in natural sources, anthropogenic activities, such as mining, agriculture, industry, etc., are also responsible for enhancing the concentration of these elements in the ecosystems up to undesirable levels. A few of these metal(loid)s serve as necessary micronutrients for life, while the others are extremely harmful and might affect the entire trophic chain upon entering the natural ecosystems due to their mobility and toxicity characteristics. Most of these heavy metal(loid) pollutants are already recognized for their harmful effects; nevertheless, their environmental control encounters obstruction due to various factors. In this context, the present report details the key points regarding the anthropogenic sources of heavy metal(loid) pollution, which are increasing rapidly with time due to the emerging industry practices and processes, the elements causing this kind of pollution, and the physicochemical processes of these elements occurring in the environment–air interface, soil, and water-air interface. These elements exert a severe impact on the environment, which could be mitigated through the development and application of various remediation techniques. Therefore, the present report concludes with a final discussion on the various remediation treatments currently available for reducing the heavy metal(loid) contamination level in both water and soil.

Seasonal Dynamics of Heavy Metal Concentrations in Water, Fish and Sediments from Haor Region of Bangladesh

Heavy metal concentrations in water, fish, and sediments from Bangladesh's haor region were investigated. Fish and sediment samples were taken once a season and evaluated using standard methods, while water samples were collected monthly. Results showed that metals in water (mg/L) were found in order of Mn (0.1694) > Cu (0.0189) > Zn (0.0045) > Pb (0.0040) > Cd (0.0028) within the maximum permissible level of Environment Conservation Rules (ECR). Mean concentrations of metal in fish (mg/kg–dry wt.) found in order of Zn (56.16) > Cu (25.47) > Mn (4.36) > Pb (2.19) > Cd (1.27) that were higher than maximum allowable level of Food and Agricultural Organization (FAO) except Cu. Metal in sediments (mg/kg) found in order of Mn (127.61) > Zn (32.51) > Pb (10.09) > Cu (5.40) > Cd (0.43), and except Cu all metal concentrations were lower than the Environmental Protection Agency's (EPA) probable effect concentrations. In water and sediments, pollution indices revealed a critical pollution threshold for water, and a range of unpolluted to highly polluted for sediments. Sampling sites had low potential ecological risk, despite the fact that metals were showing signs of a negative impact on people' health. Furthermore, bio-concentration factor for fish and water was low to extremely high, but for fish and sediment was low. The level of heavy metal contamination in haor shows the situation is alarming for biota and residents of the region. The relevant authority should control and monitor the aquatic ecology in order to protect it.

Investigate workers' health in the western industrial region, Mosul, Iraq

The current study aims to determine the level of heavy metal contamination in the Western Industrial Region of Mosul City, northern Iraq. Heavy metals such as( Pb ،Co ،Hg ) are measured In the blood serum of 40 workers in the main industrial areas of Mosul City. It was compared with the control group of (40) people from Mosul university, Where is Far away from the industrial areas and all activities. The results indicated a highly significant increase of P<0.001 in the serum of the workers in the industrial areas compared with the control group. The study investigates the impact of heavy metals on the workers' health in the industrial areas who are in direct contact with them.

An Innovative Digestion Method: Ultrasound-Assisted Electrochemical Oxidation for the Onsite Extraction of Heavy Metal Elements in Dairy Farm Slurry

Dairy farm slurry is an important biomass resource that can be used as a fertilizer and in energy utilization and chemical production. This study aimed to establish an innovative ultrasound-assisted electrochemical oxidation (UAEO) digestion method for the rapid and onsite analysis of the heavy metal (HM) contamination level of dairy slurry. The effects of UAEO operating parameters on digestion efficiency were tested based on Cu and Zn concentrations in a dairy slurry sample. The results showed that Cu and Zn digestion efficiency was (96.8 ± 2.6) and (98.5 ± 2.9)%, respectively, with the optimal UAEO operating parameters (digestion time: 45 min; ultrasonic power: 400 W; NaCl concentration: 10 g/L). The digestion recovery rate experiments were then operated with spiked samples to verify the digestion effect on broad-spectrum HMs. When the digestion time reached 45 min, all digestion recovery rates exceeded 90%. Meanwhile, free chlorine concentration, particle size distribution, and micromorphology were investigated to demonstrate the digestion mechanism. It was found that 414 mg/L free chorine had theoretically enough oxidative ability, and the ultrasound intervention could deal with the blocky undissolved particles attributed to its crushing capacity. The results of particle size distribution showed that the total volume and bulky particle proportion had an obvious decline. The micromorphology demonstrated that the ultrasound intervention fragmented the bulky particles, and electrochemical oxidation made irregular blocky structures form arc edge and cellular structures. The aforementioned results indicated that UAEO was a novel and efficient method. It was fast and convenient. Additionally, it ensured digestion efficiency and thus had a good application prospect.

Determination of Heavy Metal Contamination in Ground and Surface Water Sources in Jimma Town, Southwest Ethiopia

The quality of ground and surface water sources are contaminated by heavy metal discharged from industries, transport, municipal wastes, and hazardous waste sites as well as from fertilizers applied for agricultural intensification purposes and accidental oil spillages from tankers can result in a steady rise in contamination of both ground and surface water. Objective: To determine the level of heavy metal contamination in ground and surface water sources in Jimma town, Southwest Ethiopia. Method: The study was conducted in Jimma town in 2019 by applying a cross-sectional study design. A total of 20 samples were collected from Ground and surface water samples and stored in a clean polythene bottle that had been prewashed with 10% nitric acid and thoroughly rinsed with deionized water using standard methods of American Public Health Association (APHA), 2012. Heavy metal in water samples was analyzed by using an atomic absorption spectrophotometer. SPSS version 23 and excel software were employed for statistical analysis. A comparison of the results with the accepted international standard was carried out. Results: results for physicochemical parameters were in the range of: pH (5.9-8.71), Electrical Conductivity (83-1212 𝜇S/cm), Turbidity (0.67-5.4 NTU), and water temperature (21.9-29.8°C) and some selected heavy metals in water samples analyzed were found in the range of Pb (0.0174-0.183 mg/L), Cd (0.0029-0.031 mg/L), Cu (0.0495-0.581 mg/L), Fe (0.03-0.95 mg/L), Mn (0.00-0.55 mg/L), and Zn (0.0345-3.45 mg/L) for water sample. Conclusion: the concentrations of Pb and Cd in surface and groundwater sources were above the maximum limits recommended by WHO, USEPA, and EU. Fe, Mn, Cu, and Zn in ground and surface water were below the limits recommended by WHO, USEPA, and EU.

Contamination and ecological risk of heavy metals in Al-Uqair coastal sediments, Saudi Arabia

The level of heavy metal contamination and ecological risk, as well as the sources of contamination, of 35 sediments from the Al-Uqair coast, Saudi Arabia, were determined via inductively coupled plasma mass spectrometry. The average concentrations (dry weight) were highest for Fe (8091.51 μg/g), followed by Al (1816.60), As (14.99), Cu (11.27), Zn (7.62), Pb (3.88), Mn (3.82), Cr (3.67), Hg (2.40), Se (0.68), Ni (0.57), Cd (0.07), and Sb (0.06). The average TOC and heavy metal values, except Hg and As, were much lower than many coastal sediments elsewhere. The sediments had moderate-to-high heavy metal pollution, especially with high Hg contamination and substantial Se and As enrichment. Moreover, the sediments were at a high ecological risk for Hg, As, and Cd, moderate risk for Cu, and no-to-low risk for Pb, Zn, Ni, Cr, and Sb. Hg, Cd, Cr, As, Se, Cu, Sb, Pb, Ni, and Zn were likely from lithogenic and anthropogenic sources, including rock weathering, agricultural runoff, and untreated domestic sewage. However, Al, Fe, and Mn were naturally derived.

Evaluation of Lead, Cadmium and Nickel Contamination in Lactuca Sativa Cultivated in Savadkooh Region, Iran

Aims: To investigate the level of heavy metal contamination in the lettuce cultivated in
 Place: Savadkooh County in Mazandaran, Iran.
 Methodology: five samples were taken from the lettuce produced in this area and also from the soils in which they were cultivated, and the concentrations of Nickel, Lead, and Cadmium were measured by atomic absorption spectrometry. Descriptive and inferential statistics were used to analyze the measured data. Data analysis was performed by SPSS ver.16 at the 0.05 significance level.
 Results: The highest lead concentration, 0.07ppm, was observed in the sample No. 5 (Lettuce 5), the highest cadmium concentration, 0.008ppm, was measured in the sample No. 2 (Lettuce 2), and the highest nickel concentration, 0.07ppm, was observed in the samples No. 1 and 4 (Lettuce 1 and Lettuce 4).
 Conclusion: The results of this study show that while all the lettuces cultivated in the Savadkooh region contain some amounts of nickel, cadmium, and lead, these amounts are much lower than the limits specified in Iran’s national standard, and therefore these products are perfectly safe to consume. Also, the concentration of each heavy metal in the lettuces was found to be directly correlated with the corresponding concentration in the soil in which they were grown, indicating that the heavy metal content of the products increases with the increasing heavy metal content of the soil.

Ecological and human health risk evaluation using pollution indices: A case study of the largest mangrove ecosystem of Bangladesh

Wetlands such as mangroves are major centres of biodiversity and the production of ecosystem services from which society gathers goods and benefits. However, these attributes rely on a high environmental quality. That quality is recorded by quantitative indicators which are essential for environmental management. As such, three different salinity domains (Kachikhali, Katka, and Dublarchar) in the Sundarban Mangrove Forest, a world heritage site, were sampled in 2019 and 2020 to determine the heavy metal contamination levels and estimate the probable ecological and human health risks. The study revealed that with the exception of the changed dissolved oxygen (DO) concentration (4.5 to 6.05 mg/L), there was no significant difference between the two years in eight water quality parameters. Heavy metal concentrations followed the sequence in sediment as (mg/kg): Fe (31500) > Mn (281) > Sr (208) > Zn=Cu (77) > Co (6) > Pb (2) and in water as (μg/L): Fe (33.5) > Sr (0.6) > Cu (0.3) > Zn (0.22) > Pb (0.15) > Mn=Co (0.05). Sediment was moderately contaminated by copper as indicated by the degree of contamination (Cd=3.6 to 5.42) and the geo-accumulation index (Igeo=0.07 to 0.33). The human health hazard index (HI) values were 261, 20.6 and 20.6 for children, adult male and adult female, respectively, in Mn due to the inhalation process, indicating elevated health risk. Children can be at high risk due to manganese contamination by skin contact where HI = 2.18 ×10. In contrast, all the Hazard Quotient (HQ) and HI values for other metals were deemed to be safe (<1). This study gives both a comparison for less-contaminated sites and a model for similarly contaminated sites.

Evaluation of Heavy metals pollution around Kano municipal solid waste Dumpsites, Kano state, Nigeria

The research was conducted to assess the level of heavy metals contamination using single and integrated pollution indices in soils around municipal solid waste dumpsites of Kano Metropolis, Kano State, Nigeria. Forty two soil samples were collected from seven municipal solid waste dumpsites of Kano metropolis using circular plot method. A stainless hand auger at a depth of (0 to 15) top soils and sub-surface soils (15-30cm) depth were collected and analyzed with Flame atomic absorption spectrophotometer to determine the heavy metal concentration. The mean concentration (mg/kg) of heavy metals from the depth of (15-30 cm) were observed to follow a decreasing order Pb (7.71)&gt;Zn (0.50) &gt; Ni (0.45) &gt; Cr (0.31) &gt; Cd (0.025) while for surface soils (0- 15cm) the mean concentration were in the following order: Pb (1.77) &gt; Ni (0.49) &gt; Zn (0.30) &gt; Cr (0.27) &gt; Cd (0.012).The results showed that calculated CF and Er recorded that investigated soil samples are uncontaminated with Zn, Pb, Cd, Cr and Pb and Ni. The pollution load index (PLI) was less than unity showing that there was minimum pollution in the studied dumpsite. The potential ecological risk showed that soil samples were in the class of low contaminated with the studied heavy metals. The results showed that concentrations of heavy metals of soil samples from dumpsites location at waste dumpsites of Kano Metropolis were within limits of European Union (2002) standards.

Assessment of Heavy Metal Pollution Levels in Sediments and of Ecological Risk by Quality Indices, Applying a Case Study: The Lower Danube River, Romania

It is a well–known fact that heavy metal pollution in sediments causes serious problems not only in the Danube basin, but also in the large and small adjacent river streams. A suitable method for assessing the level of heavy metals and their toxicity in sediments is the calculation of pollution indices. The present research aims to assess heavy metal pollution in the Lower Danube surface sediments collected along the Danube course (between 180 and 60 km) up to the point where the Danube River flows into the Danube Delta Biosphere Reserve (a United Nations Educational, Scientific and Cultural Organization—UNESCO, protected area). In addition, this monitored area is one of the largest European hydrographic basins. Five heavy metals (Cd, Ni, Zn, Pb, Cu) were analyzed in two different seasons, i.e., the autumn of 2018 and the spring of 2019, using the Inductively Coupled Plasma Mass Spectrometry (ICP– MS) technique. Our assessment of heavy metal pollution revealed two correlated aspects: 1. a determination of the potential risks of heavy metals in sediments by calculating the Potential Ecological Risk Index (RI), and 2. an evaluation of the influence of anthropogenic activities on the level of heavy metal contamination in the surface sediments, using three specific pollution indices, namely, the Geo–Accumulation Index (Igeo), the Contamination Factor (CF), and the Pollution Load Index (PLI). The results of this pioneering research activity in the region highlighted the presence of moderate metal (Ni and Cd) pollution and a low potential ecological risk for the aquatic environment.

Investigating the effect of drilling mud-cutting on the contamination level of heavy metals and polycyclic aromatic hydrocarbons (case study: Well B of Azadegan South Oil Field)

سابقه و هدف: فرآیند استخراج و بهره برداری از منابع نفت و گار به چرخه تولید، ارسال و بازیافت گل حفاری یا سیال حفاری نیاز دارد، بنابراین رسیدن به ترکیب مناسب گل حفاری و بازیافت مجدد آن به­عنوان یک امر مهم و اساسی در صنعت نفت و محیط زیست به شمار می­رود. که بدین منظور به­طور معمول از روش­های مدیریت پسماند استفاده می­شود. مواد و روش: در این تحقیق سعی شده است که یک روش جایگزین به جای روش مرسوم و متداول تثبیت/جامدسازی به­عنوان فرآیند مدیریت پسماند حفاری انتخاب شود که از لحاظ محیط زیستی و همچنین از لحاظ اقتصادی به صرفه باشد. به­طور کلی 80 نمونه گرفته شد که از چهار بخش کنده شسته شده (سازند)، کنده به همراه سیال حفاری (گل برگشتی به سطح) و نمونه کنده تثبیت شده با سیمان (1:12) و نمونه کنده تثبیت شده با سیمان (1:12) و سدیم سیلیکات (1:400) تشکیل شده است. نتایج و بحث: نمونه­های تهیه شده در انواع مختلف شسته شده، همراه سیال حفاری، تثبیت شده، با سیمان و تثبیت شده با سیمان و سدیم سیلیکات به­منظور ارزیابی میزان غلظت فلزهای سنگین، هیدروکربن­های آروماتیک چند حلقه­ای و همچنین شوری مورد آزمایش قرار داده شد. غلظت فلزهای سنگین در نمونه­ها نشان داد که به هیچ نوع فرآیند مدیریت پسماند برای کنترل یا کاهش فلزهای موجود در نمونه ها نیازی نیست اما شوری و هیدروکربن­ها در عمق 1800 متر و بیشتر نیاز به تصفیه دارند. نتیجه­ گیری: جمع بندی نتایج آنالیزها نشان می­دهد که فرآیند شستشو از لحاظ محیط زیستی نسبت به روش مرسوم تثبیت/جامدسازی نیز بهتر می­باشد زیرا آلودگی­ها از روی کنده حفاری پاک شده است که در نتیجه محصول نهایی این فرآیند قابل استفاده خواهد شد، اما در روش تثبیت/جامدسازی، آلاینده­ها تصفیه نشده و فقط بدون حرکت می­شوند. بنابراین فرآیند شستشو توانسته است عامل آلودگی را به خوبی از روی کنده­های حفاری پاک کند، به­طوریکه نمونه­های شسته شده تا پایان عملیات حفاری استاندارد خاک ایران را رعایت نموده­اند.