Assessment of trace element pollution and ecological risks in a river basin impacted by mining in Colombia

Occurrence and toxicological relevance of pesticides and trace metals in agricultural soils, sediments, and water of the Sogamoso River basin, Colombia

Historical pesticide use in agriculture and trace metal accumulation have long term impact on soil, sediment, and water quality. This research quantifies legacy and current-use pesticides and trace metals, assessing their occurrence and toxicological implications on a watershed scale in the Sogamoso River basin, tributary of the Magdalena River in Colombia. Organochlorine pesticides (22), organophosphates (7), and azole fungicides (5), as well as trace metals cadmium (Cd), chromium (Cr), copper (Cu), mercury (Hg), nickel (Ni), lead (Pb), and zinc (Zn) were analyzed in croplands and along the river. Toxic units (TU) and hazard quotients (HQ) were calculated to assess the mixture toxicity. Organochlorines were detected in 84% of soils, 100% of sediments, and 80% of water samples. Organophosphates were found in 100% of soil and sediment samples, as well as in 70% of water samples. Azole fungicides were present in 79% of soils, 60% of sediments, and in 10% of water samples. Total pesticide concentrations ranged from 214.2 to 8497.7 μg/kg in soils, 569.6-12768.2 μg/kg in sediments, and 0.2-4.1 μg/L in water. In addition, the use of partition coefficient (Kd) and organic carbon fraction (foc) allowed the distribution analysis for most of the pesticides in sediments, suspended particulate matter (SPM), and water systems, but not for soils. Concentrations of trace metals Cu, Zn, Pb, and Zn exceeded international quality guidelines for agricultural soils in 16% of the samples. Furthermore, Cu and Zn concentrations exceeded sediment quality guidelines in 50 and 90% of the samples, respectively. These findings demonstrate the broad distribution of complex mixtures of trace metals, legacy organochlorines, and current-use pesticides across the basin, indicating that conventional agriculture is a significant source of diffuse pollution. Sustainable agricultural practices are needed to mitigate adverse impacts on ecosystems and human health.

Environmental effects from petroleum product transportation spillage in Nigeria: a critical review

Nigeria has struggled to meet sustainable development goals (SDGs) on environmental sustainability, transportation, and petroleum product distribution for decades, endangering human and ecological health. Petroleum product spills contaminate soil, water, and air, harming humans, aquatic life, and biodiversity. The oil and gas industry contributes to environmental sustainability and scientific and technological advancement through its supply chain activities in the transport and logistics sectors. This paper reviewed the effects of petroleum product transportation at three accident hotspots on Nigeria highway, where traffic and accident records are alarming due to the road axis connecting the southern and northern regions of the country. The preliminary data was statistically analysed to optimise the review process and reduce risk factors through ongoing data monitoring. Studies on Nigeria's petroleum product transportation spills and environmental impacts between the years 2013 and 2023 were critically analysed to generate updated information. The searches include Scopus, PubMed, and Google Scholar. Five hundred and forty peer-reviewed studies were analysed, and recommendations were established through the conclusions. The findings show that petroleum product transport causes heavy metal deposition in the environment as heavy metals damage aquatic life and build up in the food chain, posing a health risk to humans. The study revealed that petroleum product spills have far-reaching environmental repercussions and, therefore, recommended that petroleum product spills must be mitigated immediately. Furthermore, the study revealed that better spill response and stricter legislation are needed to reduce spills, while remediation is necessary to lessen the effects of spills on environmental and human health.

Vertical distribution and trace element contamination in sediment cores affected by gold mining in Colombia

The vertical distribution, level of contamination, potential ecological risks, and historical fluxes of trace elements (Pb, As, and Hg) were evaluated from 210Pb-dated sediment cores in three different areas with gold mining impacts in northern Colombia: the Atrato River (AR), the Delicias Marsh (DM) and the Encaramada Marsh (EM). All cores spanned ∼100 years; the mass accumulation rates followed the order AR > DM > EM. The average trace elements concentrations in the sediment cores were: Pb 2.41 ± 0.72, As 0.65 ± 0.32, Hg 0.07 ± 0.02 μg g-1 in the Atrato River; Pb 23.49 ± 2.59, As 2.46 ± 0.88, Hg 0.10 ± 0.02 μg g-1 in the Delicias Marsh; and Pb 9.76 ± 4.18, As 2.44 ± 1.26, Hg 0.17 ± 0.06 μg g-1 in the Encaramada Marsh. Sediments are classified according to the contamination factor (CF) and geoaccumulation index (Igeo) as low to very highly contaminated. The Pollution load index (PLI) indicates environmental deterioration (PLI> 1), and the Sediment quality guidelines (SQGs) indicate that only Hg may produce adverse biological effects in the EM core. This study is an example of the reconstruction of temporal changes in pollution levels and impacts of potentially toxic elements caused by gold mining in remote ecosystems, which can be reproduced in other areas where environmental monitoring is scarce or non-existent.

Ecological and human health risk from exposure to contaminated sediments in a tropical river impacted by gold mining in Colombia

Despite being one of the most important tropical biomes in the world, the Atrato River basin has experienced a critical ecological deterioration due to gold mining, posing a significant threat to wildlife and human health. In this study, we measured the concentrations of mercury (Hg) and arsenic (As) in sediments at various swamps within the basin. Classical indices were employed to assess the associated ecological and human health risks linked to exposure to these elements. The concentrations of Hg and As in the sediments ranged between 0.09 and 0.23 mg/kg and 0.59-2.68 mg/kg, respectively. The highest Hg values were found at upstream stations impacted by gold mining activities. For As, the highest levels were found near river mouth (except for station B), where agricultural practices are taken place. The contamination factor (CF) indicated that most of the sediments exhibited moderate contamination levels of Hg and As, depending on the specific sampling area. Conversely, the pollution load index (PLI) suggested a contamination level ranging from basic to moderate, with the exception of station B, which showed a progressive deterioration of the site. The geoaccumulation index (Igeo) indicated that the sediments were moderately contaminated with Hg, while showing signs of increasing contamination for As. According to the criteria for limiting effect concentrations (TEC), Hg concentrations exceeded the TEC at stations B and C, indicating a potential toxic risk to aquatic biota. A moderate potential ecological risk (PERI) was detected at downstream stations (D and E), and a high risk was detected at upstream stations (A, B and C). The hazard index (HI), used for non-carcinogenic risk assessment, suggested a risk of adverse effects on the population, particularly in children, with HI values exceeding 1. However, all lifetime cancer risk (TLCR) values fell within the acceptable range (1 × 10-6 to 1 × 10-4), indicating a negligible risk. Oral ingestion and inhalation were identified as the two primary routes of concern. This study serves as a valuable reference for risk assessment regarding exposures to environmental matrices that may not pose an immediate risk to human health.

Does land use and land cover affect adult communities of Ephemeroptera, Plecoptera and Trichoptera (EPT)? A systematic review with meta-analysis

We conducted a systematic review to better understand this gap and analyzed i) in which global regions are studies usually conducted, ii) the taxon studied, iii) sampling methods and iv) how authors collaborated in these studies. We also tested the relationship between different types of land use and land cover and adult EPT communities using a meta-analysis. We searched for relevant articles on the website Web of Science, using specific words related to the subject. We found 454 papers and selected 31 of them for the scientometric analysis, as they were in accordance with our objectives, and eight for the meta-analysis. Among this subset, we observed that study areas and collaborations among authors were largely restricted to a few countries in Europe and North America. Most studies used the group Trichoptera, probably due to its diversity and the longevity of the adults compared to other groups. Light traps were the most common sampling method, most likely due to their efficiency in capturing flying insects with nocturnal habits. The greatest differences in adult EPT communities were found between open areas (moorland and prairie) and forest areas. This result indicated that the conversion of forest habitats into open areas negatively impacts adult EPT communities. Our systematic review can be an important tool to help researchers choose appropriate collection methods and taxonomic groups to work with in studies on impacts of land use change on adult EPT communities.

Potentially toxic elements contents and the associated potential ecological risk in the bottom sediments of Hrazdan river under the impact of Yerevan city (Armenia)

This research aims to assess the ecological status of the Hrazdan river (Armenia) section that flows through Yerevan. The distribution of potentially toxic elements (PTE) (Cr, V, As, Zn, Cu, Ni, Co, Mn, Pb, Ti, Mo, Fe, and Ba), the bottom sediments pollution level, and the ecological risk were assessed employing the single pollution index (SPI), the enrichment factor (EF), the geo-accumulation index (I_geo), and the potential ecological risk index (RI). On sampling sites, water quality parameters (turbidity, DO, electrical conductivity (EC), salinity, TDS, pH, temperature °C) were measured as well. The correlation analysis revealed a significant correlation between Zn-Cu, Pb; Cu-Pb, Mo; Co-Fe, Ti pointing out similar sources and origination of these elements. The results indicated that the content of the studied elements in the Hrazdan bottom sediments exceeded the background content in urban soils, which was due to a set of geological and anthropogenic factors. High contents of elements were determined on the sampling sites spatially confined to the residential and industrial areas. According to EF and I_geo data, the priority bottom sediment contaminants are As, Pb, Mo, Zn, V, and Cu. The RI value varies from 196 to 316 with the mean of 246 which corresponds to the moderate-level ecological risk. On the whole, a moderate (77.8%) and a considerable (22.2%) ecological risk was revealed. The major source of Pb, Cu, Zn, and Mo contents was identified as the surface runoffs in the urban environment. This was verified by the cluster analysis results.

Efficacy of in situ active capping Cd highly contaminated sediments with nano-Fe2O3 modified biochar

Effective remediation of Cd polluted sediment is imperative for its potential damages to aquatic ecosystem. Biochar (BC) and nano-Fe₂O₃ modified BC (nFe₂O₃@BC) were conducted to remedy Cd highly contaminated sediments, and their performances, applicable conditions, and mechanisms were investigated. After 60 d capping, both BC and nFe₂O₃@BC capping inhibited Cd release from sediment to overlying water and porewater (reduction rates >99%). The released Cd concentrations in overlying water with nFe₂O₃@BC capping decreased by 1.6-11.0 times compared to those of BC capping, indicating nFe₂O₃@BC presented a higher capping efficiency. Notably, the increases of acidity and disturbance intensity of overlying water weakened the capping efficiencies of nFe₂O₃@BC and BC. BC capping was inappropriate in acidic and neutral waters (pH 3, 5, and 7) because Cd maintained a continuous release after 15 d, while nFe₂O₃@BC capping was valid in all pH treatments. Under 150 rpm stirring treatment, Cd release rates with BC and nFe₂O₃@BC capping decreased after 15 d and 30 d, respectively. At 0 and 100 rpm treatments, Cd releases treated by nFe₂O₃@BC capping finally kept a balance, indicating nFe₂O₃@BC was valid at low disturbance intensity. BC and nFe₂O₃@BC capping inhibited Cd release via weakening the influences of pH and disturbance on sediment. However, capping layers should be further processed because most adsorbed Cd in capping layers (>98%) would be re-released into overlying water. Meanwhile, excessive application of nFe₂O₃@BC could increase the risk of Fe release. The results provide novel insights into the potential applications of nFe₂O₃@BC and BC in situ capping of Cd polluted sediments in field remediation.

Ecological Risk Due to Heavy Metal Contamination in Sediment and Water of Natural Wetlands with Tourist Influence in the Central Region of Peru

In this study, the quality of sediment and surface water in two natural wetlands, Paca and Tragadero, in the central region of Peru was evaluated using pollution indices, including the geoaccumulation index, pollutant load index, modified pollution degree, potential ecological risk index, and site rank index, for four heavy metals. Principal component analysis was used to identify potential metal contaminant sources. The determination of Fe, Zn, Pb, and As was performed by flame atomic absorption spectrophotometry. The average concentrations of metals in the sediments of both lagoons decreased in the order Fe > Zn > Pb > As. The analysis of the contamination indices determined that As and Pb are the elements that contribute the most to environmental degradation in both wetlands. There is a strong correlation between the values of potential ecological risk and the modified degree of contamination, revealing that the Paca wetland has a moderate degree of contamination and potential ecological risk, while Tragadero presents a high degree of contamination and considerable potential ecological risk. The application of the site rank index showed that more than 50% of the sampling sites have between high and severe contamination. The principal component analysis presented 79.2% of the total variance. Finally, the results of this study are essential in order to carry out preventive actions for environmental protection in these lake ecosystems of great importance for many activities, such as bird watching.