guideline values
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2022 ◽  
Author(s):  
Ivan Diarra ◽  
Kristiana Ciocio ◽  
Matakite Maata

Abstract A comprehensive study was conducted to explore the concentration and distribution of heavy metals in farm soils and river sediments around a gold mining area in Fiji with particular emphasis on ecological and human health risks. Representative samples were acquired from farm sites in Matanagata Village and the Nasivi river, both situated around the Vatukoula gold mine limited (VGML), the largest operational gold mine in Fiji. Following aqua regia digestion and analysis by AAS, the average soil concentrations for Cu (110.4 mg kg–1), Cr (136.2 mg kg–1) and Cd (1.7 mg kg–1), and sediment concentrations for Pb (69.31 mg kg–1), Cd (1.82 mg kg–1), Cu (88.95 mg kg–1) and Cr (143.12 mg kg–1) were found to exceed the recommended guideline values. Based on the geo–accumulation index (Igeo) and enrichments factor (EF), the farm soils were moderately contaminated with Cd while the and sediments showed moderate to significant contamination with Pb, Ni and Cr. Ecological risk assessment confirmed moderate to considerable ecological risk in the metal–contaminated samples, with Cd and Pb generally presenting greater risk compared to other metals. Multivariate analyses including principal component analysis pointed to gold mining activities as a potential source for heavy metals in the area. Furthermore, human health risk assessment (HRA) indicated that while adults faced no significant carcinogenic or non–carcinogenic risks from metal exposure (HI < 1), children were at more risk from Co, Mn, Cr and Fe exposure, as well as potential carcinogenic risk from Cd (ILCR = 1.46E–04).


Author(s):  
S. Xie ◽  
C. Yu ◽  
B. Peng ◽  
H. Xiao ◽  
W. Zhang ◽  
...  

AbstractThis study re-assess the environmental impacts of the Dexing copper mine (the largest open-pit copper mine in Asia) on the Lean river and its two tributaries (the Dawu river and Jishui river) in the Jiangxi province, China, with particular focus on metal pollution as well as the effectiveness and side-effects of remediation activities. Results show that the Dawu river and its mixing zone with the Lean river were still heavily influenced by acid mine drainage (AMD) and loaded with elevated levels of metals, in particular Mn, Ni, and Al whose concentrations were frequently above the health-based guideline values. Manganese and Ni in the AMD-impacted waters were predicted to occur as free ions or sulfate and carbonate complexes, and thus highly-toxic to living organisms. Although Al in the AMD-impacted waters was predicted to exist largely as colloidal hydroxides with low bioavailability, abundant formation of such nano-sized particles could impair the respiratory and circulatory systems of aquatic macro-invertebrates. The integration and comparison of the results from the current and previous studies show that the concentrations of several metals (Cu, Zn, and Cd) in the Dawu river decreased significantly after 2011–2012, during which several remediation practices were implemented (e.g., AMD neutralization, excavation of contaminated sediments in impounded rivers, and rehabilitation of mine tailings and open-pit slopes). This provides evidence that these remediation practices have effectively limited the dispersion of metals from the mining area. However, AMD neutralization greatly enhanced the release of sulfate, making the mining area an even more important sulfate source.


2021 ◽  
Vol 19 (4) ◽  
Author(s):  
Detelina Belkinova ◽  
Ivanka Teneva ◽  
Stefan Kazakov ◽  
Silvia Stamenova

One of the most evident consequences of eutrophication of waters is the progressive spreading of persistent cyanobacterial blooms. They are often accompanied by the production of cyanotoxins in concentrations, which are hazardous for human health. In this research, we analysed phytoplankton communities in four lowland water bodies, for the presence of cyanobacterial blooms and toxin production. The cyanobacterial biovolumes we found, determine three of the lowland water bodies: Onogur Reservoir (OR), Asparuhov Val Reservoir (AVR), and Srebarna Lake (SL) as “Alert Level 1” of potentially hazardous levels of cyanotoxins. Cyanobacterial biovolume exceeds the threshold value of 8 mm3 L-1 (recreational waters) in AVR and SL at the end of the summer period. In OR, we registered sustainable bloom of Microcystis spp. during the whole summer season, and extremely high average seasonal value of the total biovolume (146.5 mm3 L-1). Micro-cystins were reported in all four analysed water bodies, with the highest concentration in OR (6 µg L-1). Cylindrospermopsin was detected in AVR and OR, while saxitoxins were in AVR and SL. The concentrations of cyanotoxins do not exceed the guideline values in recreational waters. However, the increased biovolumes of cyanobacteria are a signal that in three of the analysed water bodies, monitoring is recommended at the levels of cyanotoxins during the summer period.


2021 ◽  
Author(s):  
Neetha Delphin Mary Kulandaiswamy ◽  
Muralimohan Nithyanandam

Abstract Recycling and reusing of wastewater acquired high priority among the research community to meet the ever-increasing demand for groundwater, and to tackle water scarcity in every country. In this scenario, a grey water treatment system is developed with a vertical flow wetland construction tank (VFWCT)with sand, gravel and silex as media combined with phytoremediation technology using plants like Cyperus rotundus, Canna indica, Typha angustifolia, Cyperus pangorei, and Phragmites australis. The assessment parameters like color, odor, temperature, pH, electrical conductivity, free residual chlorine, Total Dissolved Solids (TDS), chloride, Sulphate, Total Suspended Solids (TSS),oil & grease, Sulphide,Biochemical Oxygen Demand (BOD), Chemical Oxygen Demand (COD), Nitrate Nitrogen, E.coli and Salmonella are used to substantiate the performance of proposed greywater treatment system. Simulation outcomes showed that most of the guideline values of the effluent are notably lower compared to the influent. The experimentation also focused on finding the best plant as Typha angustifolia for greywater treatment in the VFWCT. The plant’s rapid growth and the removal efficiency parameters of the plant with regard to the contaminants present in the greywater was highly notable. The removal efficiency was 56.56% and 50.25% for BOD5 and COD, the solids content TSS and TDS was 68% and 64.4%. The salt Cl− and Na+ removal efficiencies are 63.4% and 81.39% respectively. Majority of the parameters like pH value, Electrical conductivity, odor and TDS are higher than the groundwater aquifers, but falls within the world health organization safety limits.


2021 ◽  
Vol 9 ◽  
Author(s):  
Jajati Mandal ◽  
Sudip Sengupta ◽  
Soumyajit Sarkar ◽  
Abhijit Mukherjee ◽  
Michael D. Wood ◽  
...  

It is now well-established that not just drinking water, but irrigation water contaminated with arsenic (As) is an important source of human As exposure through water-soil-rice transfer. While drinking water As has a permissible, or guideline value, quantification of guideline values for soil and irrigation water is limited. Using published data from 26 field studies (not pot-based experiments) from Asia, each of which reported irrigation water, soil and rice grain As concentrations from the same site, this meta-analysis quantitatively evaluated the relationship between soil and irrigation water As concentrations and the As concentration in the rice grain. A generalized linear regression model revealed As in soil to be a stronger predictor of As in rice than As in irrigation water (beta of 16.72 and 0.6, respectively, p &lt; 0.01). Based on the better performing decision tree model, using soil and irrigation water As as independent variables we determined that Asian paddy soil As concentrations greater than 14 mg kg−1 may result in rice grains exceeding the Codex recommended maximum allowable inorganic As (i-As) concentrations of 0.2 mg kg−1 for polished rice and 0.35 mg kg−1 for husked rice. Both logistic regression and decision tree models, identified soil As as the main determining factor and irrigation water to be a non-significant factor, preventing determination of any guideline value for irrigation water. The seemingly non-significant contribution of irrigation water in predicting grain i-As concentrations below or above the Codex recommendation may be due to the complexity in the relationship between irrigation water As and rice grains. Despite modeling limitations and heterogeneity in meta-data, our findings can inform the maximum permissible As concentrations in Asian paddy soil.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Artyom Nikitin ◽  
Polina Tregubova ◽  
Dmitrii Shadrin ◽  
Sergey Matveev ◽  
Ivan Oseledets ◽  
...  

AbstractNatural environments are recognized as complex heterogeneous structures thus requiring numerous multi-scale observations to yield a comprehensive description. To monitor the current state and identify negative impacts of human activity, fast and precise instruments are in urgent need. This work provides an automated approach to the assessment of spatial variability of water quality using guideline values on the example of 1526 water samples comprising 21 parameters at 448 unique locations across the New Moscow region (Russia). We apply multi-task Gaussian process regression (GPR) to model the measured water properties across the territory, considering not only the spatial but inter-parameter correlations. GPR is enhanced with a Spectral Mixture Kernel to facilitate a hyper-parameter selection and optimization. We use a 5-fold cross-validation scheme along with $$R^2$$ R 2 -score to validate the results and select the best model for simultaneous prediction of water properties across the area. Finally, we develop a novel Probabilistic Substance Quality Index (PSQI) that combines probabilistic model predictions with the regulatory standards on the example of the epidemiological rules and hygienic regulations established in Russia. Moreover, we provide an interactive map of experimental results at 100 m2 resolution. The proposed approach contributes significantly to the development of flexible tools in environment quality monitoring, being scalable to different standard systems, number of observation points, and region of interest. It has a strong potential for adaption to environmental and policy changes and non-unified assessment conditions, and may be integrated into support-decision systems for the rapid estimation of water quality spatial distribution.


Toxics ◽  
2021 ◽  
Vol 9 (11) ◽  
pp. 307
Author(s):  
Victor Manuel Escot-Espinoza ◽  
Yann Rene Ramos-Arroyo ◽  
Isabel Lázaro ◽  
Isidro Montes-Avila ◽  
Leticia Carrizalez-Yañez ◽  
...  

Mine wastes from the La Aurora mine in the state of Guanajuato were generated by the flotation process and placed in four tailing dumps on the local stream while the plant operated. Given that these wastes contain toxic elements, it is important to establish their impact on the quality of several surrounding natural sources of water that are considered potential drinking water supplies. This study identified four water source types, in which the contents of arsenic (As), mercury (Hg), and thallium (Tl) were exceeded, according to international guideline values for drinking water quality. The first type of aqueous sample corresponded to leachates produced by rainwater infiltration in tailings and water–mineral waste interactions. The second type corresponded to surface water along the Xichú and La Laja Streams, and the third and fourth types involved two groundwater well samples and spring samples, respectively. The Chiquito Stream was used as a reference area that had not been impacted by the mine wastes. The isotopic signatures associated with δ34Ssulfate and δ18Osulfate compositions from the El Ojo de Agua spring are similar to those of the Santa María River and are different from those of the mine waste leachates. This study shows evidence of the presence of As in the El Ojo de Agua spring, which results from dissolution of secondary mineral phases that were produced by alteration of the mine wastes, which then migrated along the Xichú Stream system until reaching the spring. These As-bearing fine particles are prone to dissolution when in contact with this water source. Principal component analysis revealed that the observed As, Tl, and Hg can be attributed to weathering of the mine wastes. However, the results suggest that a natural contribution of these elements could be associated with rainwater–igneous rock interactions.


Water ◽  
2021 ◽  
Vol 13 (22) ◽  
pp. 3236
Author(s):  
Jianwei Wang ◽  
Nengzhan Zheng ◽  
Hong Liu ◽  
Xinyi Cao ◽  
Yanguo Teng ◽  
...  

Songnen Plain is one of the three great plains in northeast China with abundant groundwater resources. The continuous population growth and the rapid development of agriculture and economy in China has caused a series of environmental problems in the plain, such as endemic diseases caused by the accumulation of harmful substances in drinking water. This paper conducts a systematic investigation of fluorine in the groundwater of Songnen Plain. The results showed that fluorine was widespread in the groundwater of the plain in the concentration range of BDL–8.54 mg·L−1, at a mean value of 0.63 mg·L−1 and detectable at a rate of 85.91%. The highest concentrations of fluorine were found in central and southwest areas of the plain. The concentration exceeded the guideline values for fluorine in drinking water and may have varying degrees of adverse effects on adults, and especially children, in the study area. The fluorine in groundwater mainly came from the dissolution of fluorite and other fluorine-containing minerals, and the concentrations and distribution of fluorine were affected by cation exchange, groundwater flow field and hydrochemical indexes (pH, TDS and HCO3−). The study provides scientific basis for the investigation, evaluation and prevention of endemic diseases caused by fluorine.


Molecules ◽  
2021 ◽  
Vol 26 (22) ◽  
pp. 6887
Author(s):  
Suthaya Phimphilai ◽  
Pimpisid Koonyosying ◽  
Nuntouchaporn Hutachok ◽  
Tanyaluk Kampoun ◽  
Rufus Daw ◽  
...  

Rice grass has been reported to contain bioactive compounds that possess antioxidant and free-radical scavenging activities. We aimed to assess rice grass extract (RGE) drink by determining catechin content, free-radical scavenging and iron-binding properties, as well as toxicity in cells and animals. Young rice grass (Sukhothai-1 strain) was dried, extracted with hot water and lyophilized in a vacuum chamber. The resulting extract was reconstituted with deionized water (260 mg/40 mL) and served as Sukhothai-1 rice grass extract drink (ST1-RGE). HPLC results revealed at least eight phenolic compounds, for which the major catechins were catechin, epicatechin and epigallocatechin-3-gallate (EGCG) (2.71–3.57, 0.98–1.85 and 25.47–27.55 mg/40 mL serving, respectively). Elements (As, Cu, Pb, Sn and Zn) and aflatoxin (B1, B2, G1 and G2) contents did not exceed the relevant limits when compared with WHO guideline values. Importantly, ST1-RGE drink exerted radical-scavenging, iron-chelating and anti-lipid peroxidation properties in aqueous and biological environments in a concentration-dependent manner. The drink was not toxic to cells and animals. Thus, Sukhothai-1 rice grass product is an edible drink that is rich in catechins, particularly EGCG, and exhibited antioxidant, free radical scavenging and iron-binding/chelating properties. The product represents a functional drink that is capable of alleviating conditions of oxidative stress and iron overload.


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