Estimation of natural background level of Cr(VI) in ultramafic rock related alluvial aquifers of central Greece: Comparison of results by statistical and deterministic preselection method approaches

2020 ◽  
Author(s):  
Ariadne Argyraki ◽  
Konstantina Pyrgaki ◽  
Efstratios Kelepertzis ◽  
Fotini Botsou ◽  
Ifigeneia Megremi
Keyword(s):  
Statistical Approach ◽  
Ultramafic Rock ◽  
Anthropogenic Activities ◽  
Background Level ◽  
Anthropogenic Factors ◽  
Background Concentration ◽  
Natural Background ◽  
Central Greece ◽  
Alluvial Groundwater ◽  
Definition Of

<p>The definition of natural background concentration levels (NBLs) of geogenic trace metals in groundwater is a challenging issue, particularly in areas where anthropogenic activities are also present. The estimation of NBLs, in combination with environmental quality standards, in such areas is particularly important for the establishment of relevant groundwater threshold values. Over 100 groundwater samples were collected and analysed from four Cr(VI) impacted, alluvial groundwater bodies of central Greece during two consecutive hydrologic years. A common feature of the examined aquifers is the presence of weathered ultramafic rock material in the alluvial sediments. Most sampled boreholes (79 %) are used for irrigation, whereas 21 % of them are used for domestic drinking water supply. Hexavalent Cr concentrations in groundwater, ranging from below detection limit to 430 μg/L, have been attributed to both geogenic and anthropogenic factors. The scope of the present study is to estimate the NBL of Cr(VI) by using a classical statistical approach and a deterministic preselection method and test the comparability of results. In the statistical approach the distribution of samples versus Cr(VI) concentrations has been explored by using probability plots. In this way, the concentration variations within the examined groundwater bodies can be studied and the presence of sub-populations becomes evident by breaks in the slope. In the instance of the preselection method, the concentrations of a set of additional analyzed parameters in ground water, including major water ions and nitrate as well as dissolved oxygen, have been taken into account in order to categorize the samples into two groups of low and high anthropogenic influence, respectively. The comparability of the results derived by the two approaches are discussed in the context of EU Water Framework Directive.</p>

scholarly journals Natural Background Levels of Potentially Toxic Elements in Groundwater from a Former Asbestos Mine in Serpentinite (Balangero, North Italy)

Water ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 735
Author(s):  
Elisa Sacchi ◽  
Massimo Bergamini ◽  
Elisa Lazzari ◽  
Arianna Musacchio ◽  
Jordi-René Mor ◽  
...  
Keyword(s):  
Toxic Elements ◽  
Statistical Evaluation ◽  
Anthropogenic Activities ◽  
Potentially Toxic Elements ◽  
Contaminated Site ◽  
Natural Background ◽  
Background Levels ◽  
High Concentrations ◽  
Definition Of ◽  
Real Challenge

The definition of natural background levels (NBLs) for potentially toxic elements (PTEs) in groundwater from mining environments is a real challenge, as anthropogenic activities boost water–rock interactions, further increasing the naturally high concentrations. This study illustrates the procedure followed to derive PTE concentration values that can be adopted as NBLs for the former Balangero asbestos mine, a “Contaminated Site of National Interest”. A full hydrogeochemical characterisation allowed for defining the dominant Mg-HCO3 facies, tending towards the Mg-SO4 facies with increasing mineralisation. PTE concentrations are high, and often exceed the groundwater quality thresholds for Cr VI, Ni, Mn and Fe (5, 20, 50 and 200 µg/L, respectively). The Italian guidelines for NBL assessment recommend using the median as a representative concentration for each monitoring station. However, this involves discarding half of the measurements and in particular the higher concentrations, thus resulting in too conservative estimates. Using instead all the available measurements and the recommended statistical evaluation, the derived NBLs were: Cr = 39.3, Cr VI = 38.1, Ni = 84, Mn = 71.36, Fe = 58.4, Zn = 232.2 µg/L. These values are compared to literature data from similar hydrogeochemical settings, to support the conclusion on their natural origin. Results highlight the need for a partial rethink of the guidelines for the assessment of NBLs in naturally enriched environmental settings.

scholarly journals A Broad-Scale Method for Estimating Natural Background Levels of Dissolved Components in Groundwater Based on Lithology and Anthropogenic Pressure

Water ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1531
Author(s):  
Julie Lions ◽  
Nicolas Devau ◽  
Daniel Elster ◽  
Denitza D. Voutchkova ◽  
Birgitte Hansen ◽  
...  
Keyword(s):  
Statistical Approach ◽  
Background Level ◽  
Nonparametric Test ◽  
Average Concentration ◽  
Anthropogenic Pressure ◽  
Natural Background ◽  
Eu Member States ◽  
Water Point ◽  
Wide Range ◽  
Dissolved Components

The Water Framework Directive (WFD) requires EU member states to assess the chemical status of groundwater bodies, a status defined according to threshold values for harmful elements and based on/the natural background level (NBL). The NBL is defined as the expected value of the concentration of elements naturally present in the environment. The aim of this study is to propose a methodology that will be broadly applicable to a wide range of conditions at the regional and national scale. Using a statistical approach, the methodology seeks to determine NBLs for SO4, As, Cd, Cr, Cu, Ni, Zn, and F based on the lithology of aquifers from which groundwater monitoring data were collected. The methodology was applied in six EU countries to demonstrate validity for a wide range of European regions. An average concentration was calculated for each parameter and chosen water point and linked to a lithology. Based on the dataset created, significant differences between lithologies and pressure categories (urban, agricultural, industrial, and mining) were tested using a nonparametric test. For each parameter, 90th percentiles were calculated to provide an estimation of the maximum natural concentrations possible for each lithology.

Influence of Anthropogenic Pressures on Groundwater Quality from a Rural Area

2017 ◽  
Vol 68 (8) ◽  
pp. 1744-1748
Author(s):  
Catalina Stoica ◽  
Gabriela Geanina Vasile ◽  
Alina Banciu ◽  
Daniela Niculescu ◽  
Irina Lucaciu ◽  
...  
Keyword(s):  
Water Quality ◽  
Anthropogenic Activities ◽  
Groundwater Resources ◽  
Bacterial Load ◽  
Animal Husbandry ◽  
Anthropogenic Factors ◽  
Contamination Level ◽  
Anthropogenic Pressures ◽  
Limit Values ◽  
Physico Chemical

During the past few decades, the anthropogenic activities induced worldwide changes in the ecological systems, including the aquatic systems. This work analysed the contamination level of groundwater resources from a rural agglomeration (Central-Western part of Prahova County) by biological and physico-chemical approaches. The study was performed during the autumn of 2016 on several sampling sites (four drilling wells, depth higher than 100 m supplying three villages; two wells lower than 10 m depth and one spring). The water quality was evaluated by comparison with the limit values of the drinking water quality legislation (Law no.458/2002) and the Order 621/2014 (applicable to all groundwater bodies of Romania). The results showed that phenols and metals (iron and manganese) exceeded the threshold values in all sampling sites. Moreover, the anthropogenic factors including agriculture, use of fertilizers, manures, animal husbandry led to an increase of the bacterial load, particularly at wells sites.

scholarly journals Anthropogenic nitrate in groundwater and its health risks in the view of background concentration in a semi arid area of Rajasthan, India

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Abdur Rahman ◽  
N. C. Mondal ◽  
K. K. Tiwari
Keyword(s):  
Health Risk ◽  
Human Health ◽  
Health Risks ◽  
Anthropogenic Activities ◽  
Probabilistic Approach ◽  
Hazard Index ◽  
Arid Area ◽  
Oral Exposure ◽  
Background Concentration ◽  
Semi Arid

AbstractAn increased nitrate (NO3−) concentration in groundwater has been a rising issue on a global scale in recent years. Different consumption mechanisms clearly illustrate the adverse effects on human health. The goal of this present study is to assess the natural and anthropogenic NO3− concentrations in groundwater in a semi arid area of Rajasthan and its related risks to human health in the different groups of ages such as children, males, and females. We have found that most of the samples (n = 90) were influenced by anthropogenic activities. The background level of NO3− had been estimated as 7.2 mg/L using a probabilistic approach. About 93% of nitrate samples exceeded the background limit, while 28% of the samples were beyond the permissible limit of 45 mg/L as per the BIS limits. The results show that the oral exposure of nitrate was very high as compare to dermal contact. With regard to the non-carcinogenic health risk, the total Hazard Index (HITotal) values of groundwater nitrate were an average of 0.895 for males, 1.058 for females, and 1.214 for children. The nitrate health risk assessment shows that about 38%, 46%, and 49% of the samples constitute the non-carcinogenic health risk to males, females, and children, respectively. Children were found to be more prone to health risks due to the potential exposure to groundwater nitrate.

scholarly journals Estimating Soil Water Susceptibility to Salinization in the Mekong River Delta Using a Modified DRASTIC Model

Water ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 1636
Author(s):  
Thanh N. Le ◽  
Duy X. Tran ◽  
Thuong V. Tran ◽  
Sangay Gyeltshen ◽  
Tan V. Lam ◽  
...  
Keyword(s):  
Land Use ◽  
Soil Water ◽  
Management Practices ◽  
Global Climate ◽  
Anthropogenic Activities ◽  
Rapid Development ◽  
Anthropogenic Factors ◽  
Drastic Model ◽  
River Catchment ◽  
Modified Drastic

Saltwater intrusion risk assessment is a foundational step for preventing and controlling salinization in coastal regions. The Vietnamese Mekong Delta (VMD) is highly affected by drought and salinization threats, especially severe under the impacts of global climate change and the rapid development of an upstream hydropower dam system. This study aimed to apply a modified DRASTIC model, which combines the generic DRASTIC model with hydrological and anthropogenic factors (i.e., river catchment and land use), to examine seawater intrusion vulnerability in the soil-water-bearing layer in the Ben Tre province, located in the VMD. One hundred and fifty hand-auger samples for total dissolved solids (TDS) measurements, one of the reflected salinity parameters, were used to validate the results obtained with both the DRASTIC and modified DRASTIC models. The spatial analysis tools in the ArcGIS software (i.e., Kriging and data classification tools) were used to interpolate, classify, and map the input factors and salinization susceptibility in the study area. The results show that the vulnerability index values obtained from the DRASTIC and modified DRASTIC models were 36–128 and 55–163, respectively. The vulnerable indices increased from inland districts to coastal areas. The Ba Tri and Binh Dai districts were recorded as having very high vulnerability to salinization, while the Chau Thanh and Cho Lach districts were at a low vulnerability level. From the comparative analysis of the two models, it is obvious that the modified DRASTIC model with the inclusion of a river or canal network and agricultural practices factors enables better performance than the generic DRASTIC model. This enhancement is explained by the significant impact of anthropogenic activities on the salinization of soil water content. This study’s results can be used as scientific implications for planners and decision-makers in river catchment and land-use management practices.

scholarly journals Estimation of the return period of rockfalls according to the block size

2016 ◽  
Author(s):  
Valerio De Biagi ◽  
Maria Lia Napoli ◽  
Monica Barbero ◽  
Daniele Peila
Keyword(s):  
Return Period ◽  
Statistical Approach ◽  
Historical Data ◽  
Risk Estimation ◽  
Block Size ◽  
Return Time ◽  
Correct Definition ◽  
Protection Devices ◽  
Definition Of ◽  
Rockfall Protection

Abstract. With reference to the rockfall risk estimation and the planning of rockfall protection devices one of the most critical and most discussed problems is the correct definition of the design block taking into account its return period. In this paper, a methodology for the assessment of the design block linked with its return time is proposed and discussed, following a statistical approach. The procedure is based on the survey of the blocks already detached from the slope and accumulated at the foot of the slope and the available historical data.

Trophic and functional organization of the benthic macrofauna in the lagoon of Boughrara – Tunisia (SW Mediterranean Sea)

2014 ◽  
Vol 95 (4) ◽  
pp. 647-659 ◽  
Author(s):  
Ines Khedhri ◽  
Hanem Djabou ◽  
Ahmed Afli
Keyword(s):  
Functional Organization ◽  
Anthropogenic Activities ◽  
Benthic Macrofauna ◽  
Anthropogenic Factors ◽  
Deposit Feeders ◽  
Trophic Resources ◽  
Open Sea ◽  
Seasonal Monitoring ◽  
Lagoon Environment ◽  
The Impact

The lagoon of Boughrara is the largest lagoon in Tunisia. For several decades it has been subject to the impact of increasing anthropogenic activities, and also to environmental stressors due to climate change and the low renewal of its waters. The present work is a contribution to the study of the functional organization of the benthic macrofauna of the lagoon of Boughrara 3 years after the extension of the channel ‘El Kantra’ which connects this lagoon to the open sea. In total, 13 stations facing the main prospective sources of disturbance and in areas likely to be more polluted were seasonally sampled during 2009–2010. Seasonal monitoring of the abiotic parameters shows a spatial heterogeneity linked to environmental and anthropogenic factors, including hydrodynamics, sedimentary texture and anthropogenic activities. The community of benthic macrofauna is generally poorly diversified at lagoonal-marine stations undergoing influences of both the marine and lagoon environment. The extreme seasons in terms of temperature and salinity seem to have an important role in the reduction of biodiversity in the lagoon of Boughrara. The trophic structure of the macrobenthic community is generally dominated by selective deposit feeders, and seems to be linked more to the availability of trophic resources than to disturbance.

scholarly journals Anthropogenic Nitrate Pollution in Groundwater and Its Health Risks in The View of Background Concentration in a Semi-Arid Area of Rajasthan

2021 ◽  
Author(s):  
Abdur Rahman ◽  
N.C. Mondal ◽  
K.K. Tiwari
Keyword(s):  
Health Risk ◽  
Human Health ◽  
Health Risks ◽  
Anthropogenic Activities ◽  
Arid Area ◽  
Oral Exposure ◽  
Background Concentration ◽  
Dermal Contact ◽  
Groundwater Samples ◽  
Semi Arid

Abstract An increased nitrate (NO3-) concentration in groundwater has been a rising issue on a global scale in recent years. Through different consumption mechanisms, it clearly illustrates the adverse effects on human health. The goal of this present study is to assess the natural and anthropogenic NO3- concentration in groundwater and its related risks to human health in the different groups of ages such as children, males, and females. Groundwater samples (n=101) were obtained and analysed for their physicochemical components, along with the nitrate concentration in a semi-arid area of Rajasthan. The results show that most of the samples were influenced by anthropogenic activities. The background and anthropogenic levels had been estimated and marked as 7.2 mg/L and 13.3 mg/L for the background and anthropogenic concentrations, respectively. About 83% of nitrate samples were exceeded the background limit, while 28% of the samples were beyond the permissible limit of 45 mg/L as stated by the Bureau of Indian Standards (BIS). Nitrate health risks were also measured by oral intake and dermal contact sources for the residents in this area. The oral exposure of nitrate was very high as compare to dermal contact. With regards to the non-carcinogenic health risk, the total Heath Index (HITotal) values of groundwater nitrate in the study area varied from 0.045 to 3.153 with an average of 0.964 for males, 0.053 to 3.726 with an average of 1.139 for females, and 0.061 to 4.278 with an average of 1.308 for children. The nitrate health risk assessment shows that about 38%, 46%, and 49% of groundwater samples constitute the non-carcinogenic health risk to males, females, and children, respectively.

scholarly journals On the Uncertainty of the Image Velocimetry Method Parameters

Hydrology ◽  
2020 ◽  
Vol 7 (3) ◽  
pp. 65
Author(s):  
Evangelos Rozos ◽  
Panayiotis Dimitriadis ◽  
Katerina Mazi ◽  
Spyridon Lykoudis ◽  
Antonis Koussis
Keyword(s):  
Confidence Intervals ◽  
Statistical Approach ◽  
Random Number Generator ◽  
Surface Flow ◽  
Surface Velocity ◽  
A Value ◽  
Image Velocimetry ◽  
Interrogation Area ◽  
Definition Of ◽  
Parameter Values

Image velocimetry is a popular remote sensing method mainly because of the very modest cost of the necessary equipment. However, image velocimetry methods employ parameters that require high expertise to select appropriate values in order to obtain accurate surface flow velocity estimations. This introduces considerations regarding the subjectivity introduced in the definition of the parameter values and its impact on the estimated surface velocity. Alternatively, a statistical approach can be employed instead of directly selecting a value for each image velocimetry parameter. First, probability distribution should be defined for each model parameter, and then Monte Carlo simulations should be employed. In this paper, we demonstrate how this statistical approach can be used to simultaneously produce the confidence intervals of the estimated surface velocity, reduce the uncertainty of some parameters (more specifically, the size of the interrogation area), and reduce the subjectivity. Since image velocimetry algorithms are CPU-intensive, an alternative random number generator that allows obtaining the confidence intervals with a limited number of iterations is suggested. The case study indicated that if the statistical approach is applied diligently, one can achieve the previously mentioned threefold objective.

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