Contamination of As, Cd, Cr, Hg and Pb in soils in Arica commune (Chile)

The objectives of this study are (a) to determine the background concentration of As, Cd, Cr, Hg and Pb in Arica commune; (b) to determine the degree of soil contamination in Arica city using environmental indices and (c) to evaluate the human health risk of these potentially toxic elements. In the rural area of Arica commune, 169 samples were taken and 283 samples were taken in the urban area of Arica city. Total concentrations of Cd, Pb and Cr were determined by EPA 3052 and EPA 6010 C. Mercury was determined by EPA 7473. Arsenic was determined by EPA 7061A. The available concentrations of As and Cr were determined by dilute hydrochloric acid and EPA 6010C. Environmental indices were applied for pollution and US EPA model was used to evaluate human health risk. Background concentrations were As 18.2, Cd 1.12, Cr 73.2, Hg 0.02 and Pb 11.8 mg kg-1, respectively. Environmental indices show that soil samples are located between slightly contaminated to extremely contaminated. Human health risk analysis shows that children have higher levels of risk than adults. The analysis with available concentrations of As and Cr shows no carcinogenic risk for adults and children, but 81% and 98% of the samples were between 10-6 and 10-4, that means intermediate risk.

Trace element contamination in soils surrounding the open-cast coal mines of eastern Raniganj basin, India

Trace element pollution of soils surrounding coal-mining areas affects the health of local communities. The increasing coal-mining and associated activities in the Raniganj basin (east India) have led to increased soil concentration of certain trace elements. To quantify the elevated trace element (TE) concentrations in the soil surrounding coal-mining areas, 83 surface soil, coal, and shale samples were collected from open-cast mining areas of the eastern Raniganj basin. The soils present are sandy silt, silty sand, and silty in nature, but almost no clay. They are acidic (pH = 4.3) to slightly alkaline (pH = 7.9) with a mean electrical conductivity (EC) of 340.45 µS/cm and a mean total organic carbon (TOC) of 1.80%. The northern and western parts of the study area were found to be highly polluted by certain metallic trace elements. The relevant environmental indices, geoaccumulation index (Igeo), contamination factors (CF), enrichment factors (EF), and pollution load index (PLI) were calculated and assessed. Analysis revealed that Cr was highly enriched in these soil samples, followed by Pb, Co, Cu, Cd, Fe, Ni, Mn, Zn, As, and Al. Geostatistical analyses (correlation coefficients and principal component analysis) indicated that the occurrence of some trace elements (Al, Cd, Co, Cu, Fe, Mn, Ni, and Zn) is most likely linked to the various coal-mining operations in the study area. However, the anomalous Cr and Pb distributions are likely influenced by other anthropogenic, mainly industrial, inputs besides coal mining. These results justify the adoption of rigorous soil monitoring programs in the vicinity of coal-mining areas, to identify pollution hotspots and to develop strategies to reduce or mitigate such environmentally damaging pollution.

Effect of landscape pattern changes and environmental indices on land surface temperature in a fragile ecosystem in southeastern Iran

Climate change and urbanization along with uncontrolled development in less developed countries have led to an increased ecosystems' thermal environment. Some factors such as environmental indices and landscape pattern changes can alter Land Surface Temperature (LST). Thus, the accurate evaluation of the relationship between these factors and LST is considered important for managing ecosystems, especially fragile ones under high stress. The southeast of Iran has witnessed many destructions in the environmental dimension in the past years. Moreover, this region has a low socio-economic situation, which increases the need to study in this region. In the present study, we used Landsat TM5 satellite images (1989), Landsat 8 OLI/TIRS ones (2019), and Google Earth Engine (GEE) system to prepare the maps of temporal-spatial LST changes, Land Use/Land Cover (LULC), and selected environmental indices including Normalized Difference Vegetation (NDVI), Built-up (NDBI), Water Indices (NDWI), Land Surface Moisture (LSM) and albedo. Then, the correlation levels of LST with the aforementioned indices were assessed by using Geographically Weighted Regression (GWR), as well as assessing LST variation following LULC change. In addition, the Moran index was used to analyze global and local spatial autocorrelation. The results represented an 8.67-degree increase in the mean LST during 1989-2019. Urban and built-up areas had a significant effect on increasing the temperature of the region. Additionally, water bodies and vegetation cover in the region were the most crucial parameters in LST reduction. All of the applied indices were strongly related to LST (>0.70), while some exhibited more correlation in each year. Further, the highest correlation of LST was observed with LSM and NDBI in 1989, as well as with NDVI and NDWI during 2019. In addition, the Moran index value reduced from 1989 to 2019 (from 0.93 to 0.89). Finally, the region rehabilitation based on sustainable development principles played an important role in the direct and indirect decrease in LST.

Geospatial passives for dynamic vegetation monitoring around thermal power plants

As point sources of pollution, thermal power plants (TPPs) emanate hazardous gaseous and particulate matter that are of significant detriment to surrounding biological landscapes. To provide support to ecological conservation and resource management in developing countries, this study aims to establish a cost effective and robust geospatial methodology for dynamic vegetation monitoring of local pollution zones around TPPs using passive satellite-based indicators. The extent and severity of hazardous bio-influence around four TPPs is identified and monitored for a period of 5 years, using vegetation indices (VIs). High correlations of vegetation health with distance from TPPs have also been identified, signifying the hazardous impact of TPP emissions to surrounding vegetation. Variations in behavior of zones of high pollutant concentration are observed both in space and time, as a response to local seasonal weather, nature of fuel used in TPP, and type and areal coverage of vegetation around the power plants. Winter and Monsoon seasons have been identified to create favorable conditions for sustaining high pollution concentration around TPPs, and hence, the extent of hazardous bio-influence zones in these seasons is maximum. Moreover, oil-based power plant is revealed to be associated with large radial zones of degraded vegetation around it and, therefore, poses greater ecological hazard than gas-powered TPPs. The average bio influence zone measured for the test sites has been found to be 1660 m that ranges from 1600 to 1730 m for different power plants, explaining variable behavior of the used fuel and surrounding vegetation conditions. In this way, the study stresses upon the importance of geospatial data and analytical frameworks in reliable and economical monitoring of environmental pollution associated with anthropogenic sources, using passive environmental indices derived from remote data.

Evaluation of metals and trace elements in sediments of Kanyakumari beach (southernmost India) and their possible impact on coastal aquifers

Beach sediments of Kanyakumari at the southernmost India were evaluated for metals and trace elements and to assess their possible impact on coastal ecosystems. Positive correlations (except for Cd and Sr) between them indicated metamorphic lithologies and heavy mineral deposits as possible sources. Significant-extremely high enrichment and very high contamination of Th, Zr, Mo, Ti and U reflected the presence of different heavy minerals. The geo-accumulation index, however, mirrored their variable abundances at different sites. Association of Cd with P suggested the influence of anthropogenic solid waste from fishing industry. It might have caused >41-fold enrichment of Cd and the Fe- Mn-oxides possibly acted as scavengers for 13-fold enrichment of As compared to UCC. Concentrations of Zn and Cr between ERL and ERM in 13% and 93% of the samples, and Ni > ERM in 87% of sediments suggest their bioavailability to seawater with a potential risk for coastal aquifers.

Hazardous heavy metals in the pristine lacustrine systems of Antarctica: Insights from PMF model and ERA techniques

A comprehensive study was presented on the ecological risk, distribution, and quantitative source apportionment of heavy metals in the selected lacustrine systems of Schirmacher Hills using various environmental indices and methods. A total of 25 sediment samples from 16 lakes were collected around scientific research stations and analyzed for metals. Geochemical approaches and ecological risk assessment methods were implemented to characterize and evaluate the contamination level and associated risk in the lacustrine systems. Moreover, statistical techniques and a positive matrix factorization (PMF) model were indorsed to understand metals' association and apportion their probable sources. Results revealed that most of the heavy metals (mean concentration in ppm) such as Al (77,504.09), Cd (1.36), Co (29.52), Cr (102.75), Cu (65.19), Fe (57,632.87), Mn (679.05), Ni (49.13), Pb (10.11), and Zn (253.78) are originated from natural weathering of source rocks (78.53%) followed by human-induced actions/ station activities coupled with atmospheric deposition (21.47%). Environmental risk assessment (ERA) techniques suggest that the lakes in the study area are under minimal to moderate enrichment/ contamination category and experienced minimal to adverse biological effects where metal toxicity risk is minimal.

Integration of cancer and non-cancer human health risk assessment for Aniline enriched groundwater: a fuzzy inference system-based approach

This study outlines a methodological approach to evaluate the environmental risk from integrating data of Aniline in groundwater near to coal-based industries using fuzzy logic, and a comprehensive artificial intelligence approach and the results were validated using conventional risk assessment approach. The Aniline is well-known carcinogenic pollutant released from coal-based industries, so to understand the associated cancer and non-cancer risks (CR and NCR), 15 groundwater samples were analyzed for Aniline, whose concentration was found within the range 0.10-0.34 mg/L, which is up to 68 times higher than the permissible limit. The alkaline pH of water samples resulted in reduced attractive forces between the soil particles with Aniline, and thereby increased percolation of Aniline into the groundwater. Women were at least risk in terms of Mamdani cancer risk (MCR) and Mamdani hazard index (MHI) which was observed up to 1.04E-04 and 3.04, respectively, while maximum MCR and MHI were observed in case of children, i.e., 1.21-E04 and 3.26, respectively. The newly proposed fuzzy inference rule-based Mamdani combined index (MCI) depicts the combined effect of both CR and NCR and was found to be highly correlated with each other. The detailed comparison analysis exhibited that the fuzzy inference rule-based MCI has better resolving ability to find out priority risk prediction over conventional methods under efficient parameter uncertainty control. Hence, it can be concluded that the fuzzy analyses can reflect human considerations and expertise in indices, empowering them to manage nonlinear, questionable, uncertain and subjective data. Therefore, this tool can predict the more meaningful risk estimation of any pollutants on human health.

Cleaner and sustainable processes for extracting phenolic compounds from bio-waste

The frequent environment-unfriendly treatments of agro-industrial bio-wastes cause severe pollution through air pollution and through residual effluents and hazardous solid waste. These bio-wastes can contain phenolic compounds, forms of phenolic acids and flavonoids in plants. They are however the most abundant class of many phytochemicals and have been given great interest due to their health advantage and high economic value. An interesting upgrading of these bio-wastes may consist in obtaining a concentrated extract of phenolic compounds using no-toxic solvents, hence protecting the environment and human health. In this work, different alternatives of the extraction process were evaluated using an exergetic analysis. The energy and water consumptions, CO₂ emissions, exergetic yield, wasted and destroyed exergy were calculated. It was found that several alternatives for recycle streams were convenient (streams with higher chemical exergy were not discharged into the environment). The energy and water consumption for the best alternative (ethanol-water ratio 1/1 including recycle stream, named E-W 1/1 Rec) were 567 MJ/h and 105 kg/h, respectively and the CO₂ emission was 105 kg/h. The calculated exergy destruction indicated that the evaporation and distillation stages may be optimized towards a more sustainable operation. It is not advisable to dry the bio-waste if it will be immediately processed once generated.

Sediment metal enrichment and ecological risk assessment of ten ports and estuaries in the World Harbours Project

Ten global harbours were assessed for sediment quality by quantifying the magnitude of anthropogenic change and ecological risk. Anthropogenic change (enrichment) was high for Derwent River and Sydney estuary, moderate for Santander Harbour, Rio de Janeiro and Dublin Port, slight for Hong Kong, minimal for Darwin. All 10 enrichment indices used showed similar results. Derwent River sediment was rated at high ecological risk, followed by Sydney and Santander estuaries with moderate risk. Auckland and Darwin sediments exhibited minimal ecological risk and sediment in the remaining harbours (Dublin, Hong Kong, Ravenna, Ria de Vigo and Rio de Janeiro) were assessed at slight ecological risk. The extraordinary variety of environments and types/quantities/qualities of data investigated resulted in as much a critique and development of methodology, as an assessment of human impact, including unique techniques for elemental normalisation and contaminant classification. Recommendations for an improved technical framework for sediment quality assessment are provided.

Relationship between enrichment, toxicity, and chemical bioavailability of heavy metals in sediments of the Cai River estuary

This study focuses on heavy metals (HMs) (Cr, Co, Ni, Cu, Zn, and Pb) along with Al, Fe, Mn, organic carbon (TOC), and carbonates (TIC) detected in surface sediments from the River Cai-Nha Trang Bay estuarine system (South China Sea). The enrichment factors (EF_Al and EF_Fe), Geoaccumulation Index (I_geo), Adverse Effect Index (AEI), and toxic units (TUs) were used to assess the HM enrichment and toxicity in the sediments. The selective single-step extraction procedure was applied to determine the chemical forms of HMs in order to assess their potential bioavailability. The EF and I_geo calculations suggest that sedimentary Fe, Mn, Cr, Co, Ni, and Cu are derived mainly from natural sources (EF_Al and EF_Fe < 1.5 and I_geo < 0 at all sampling sites), while the moderate Pb enrichment (EF_Al and EF_Fe ≥ 2 and I_geo ≥ 1 at all sampling sites) may indicate a moderate contamination. Cr, Cu, and Zn suggest low potential toxicity, while both Ni and Pb show above threshold AEI levels (AEI ≥ 1) and contribute up to 30-40% to the sum of toxic units (∑TUs) at all sampling sites. According to their comparative ability to mobilize metals from the sediments, the single extractants applied were arranged in descending order: acetic acid > ammonium oxalate >> sodium pyrophosphate. All single-step extractants mobilized substantive amounts of Pb (7-30% of total content, on average) from sediments, indicating considerable potential bioavailability. Among HMs studied, the percentage of acid-soluble Pb (23-35%) significantly exceeded the respective ranges in the sediments of other coastal regions. Pearson's correlation and PCA analyses revealed that among HMs studied, Cr, Ni, and Co enrichment is positively associated with the salinity gradient due to the accumulation of the most fine-grained Fe-rich aluminosilicate host minerals in the bay zone, while sediments in the transitional zone are mainly enriched in Cu, Zn, and Pb due to the local accumulation of metal-rich detrital heavy minerals. The percentages of bioavailable forms of most of the HMs are negatively associated with the salinity gradient due to the preferential accumulation with fluvial Fe/Mn oxyhydroxides in the frontal and transitional zones. Generally, distribution of the enrichment indices of most of the HMs is not associated or even negatively associated with the percentage of the bioavailable forms. The intensity of monsoonal precipitation is shown to be an essential factor in the natural enrichment of estuarine sediments with bioavailable metals. Determining the local geochemical background of HMs and Pb, in particular, is a major goal for future study.