Heavy metal contamination in soils of a decommissioned landfill southern Brazil: Ecological and health risk assessment.

The incorrect disposal of waste negatively influences the population's quality of life and harms the environment. In Brazil, waste disposal in the open air is still a reality, which generates concerns about the contamination of the areas surrounding these dumpsites. The present work evaluated the possible environmental risks of a deactivated dumpsite in southern Brazil. The soil was characterized by physical and chemical tests, emphasizing the analysis of heavy metals Al, Fe, Cu, Mn, and Zn. Using geostatistical tools, it was possible to determine the distribution of these heavy metals in the influence of the landfill, since the metals Mn, Fe, and Zn showed a significant difference about the reference soil, indicating that they came from leaching from the landfill. The dispersion of the metals along the slope showed a tendency towards mobility since the highest concentrations were at elevations below the landfill. The area was considered contaminated due to the high scores of the evaluated indexes pollution, as the Improved Nemerow Pollution Index, which considers pollutant concentration, toxicity, and environmental impact to provide a measure of contamination, and was equivalent to 6.44, indicating that the area is contaminated. However, it presented low ecological risks, with a potential ecological risk of 18.55. As well as low risks to human health, with hazard index below the limit considered critical to health (HI < 1). Thus, the results of this study showed that the metals are released around the deactivated deposit, which compromises the environmental safety of the site, mainly due to its proximity to bodies of water that supply the region. Thus, the permanent control and monitoring of the areas of deactivated dumpsites are essential to avoid further pollution and should be included in the management plans for deactivating these deposits throughout the country.

Bioaccumulation and health risk assessment of trace metal contamination in the musculature of the trahira fish (Hoplias malabaricus) from two neotropical rivers in southeastern Brazil.

BACKGROUND: Fish are an important source of nutrition for humans. Artisanal fishing plays a fundamental role in Brazil fish production. In Brazil, the unrestrained increase, diffusion, and little importance for environmental causes of other economic activities, such as the agricultural industry, has caused irreparable damage, leading to the contamination of water bodies. Among the countless pollutants that reach water bodies, trace metals are extremely problematic. Here, we evaluated the bioaccumulation and health risk of trace metal contamination in the musculature of the trahira fish (Hoplias malabaricus), collected from two rivers in southeastern Brazil. METHODS: During the period from May 2017 to November 2019, 90 fish were collected, 45 from each river. River water samples were also taken during the same collection periods. From fish, muscle tissue samples were taken, and together with river water samples, analyzed for the recovery of trace metals (Al, Cr, Mn, Fe, Ni, Cu, As, Cd, and Pb) through the technique of Inductively Coupled Plasma Mass Spectrometry (ICP-MS). RESULTS: In general, fish as well as the waters of the Jacaré-Guaçú River had higher concentrations of metals. The elements Al, Cr and Cd stood out from the others analyzed metals for having a hazard index (HQ) above 1 (Al), for being up to 10 times above the concentrations allowed by Brazilian legislation (Cr) and for having a high bioconcentration factor (Cd), indicating a biomagnification process through the food chain. CONCLUSION: In general, trace metal concentrations in the waters and fish of the Jacaré-Guaçú were higher than in the Jacaré-Pepira, which shows that the Jacaré-Guaçú is the one that suffers more anthropogenic action between the two rivers. In addition, some elements such as Al, Cr and Cd, due to its high concentrations, should receive some attention as they can pose risks to the health of fish, which can jeopardize the survival of their populations, and especially to humans who use these animals as a food source.

Trace elements in farmland soils and crops, and probabilistic health risk assessment in areas influenced by mining activity in Ecuador.

Consumption of food grown in contaminated soils may be a significant human exposure pathway to pollutants, including toxic elements. This study aimed to investigate the pollution level of trace elements in farmland soil and crops collected in orchards from Ponce Enriquez, one of the Ecuador's most important gold mining areas. The concentration of arsenic (As), cadmium (Cd), chrome (Cr), copper (Cu), nickel (Ni), lead (Pb), and zinc (Zn) was analyzed in soil and crop samples (celery, chives, corn, herbs, lettuce, turnips, green beans, cassava, and carrots). In addition, a probabilistic human health risk assessment, in terms of hazard quotients (HQ) and cancer risk (CR), was conducted to assess the potential risk related to local crop ingestion. The contents of As, Cr, Cu, and Ni in soils exceeded the Ecuadorian quality guidelines for agricultural soils. The trace elements concentration in local crops was higher than the maximum permissible levels set by the Food and Agriculture Organization of the United Nations (FAO). The HQ and CR of local crop ingestion were several orders higher than the safe exposure threshold, mainly for lettuce, chives, and turnips. Our results revealed that inhabitants of the study area are exposed to developing carcinogenic and non-carcinogenic effects due to long-term food consumption with high trace elements. This study sheds light on the need to assess further the quality of agricultural soils and crops grown in mining areas with signs of contamination to guarantee consumer food safety.

Antarctic heavy metal pollution and remediation efforts: state of the art of research and scientific publications.

In Antarctica, human activities have been reported to be the major cause of the accumulation of heavy metal contaminants. A comprehensive bibliometric analysis of publications on heavy metal contamination in Antarctica from year 2000 to 2020 was performed to obtain an overview of the current landscape in this line of research. A total of 106 documents were obtained from Scopus, the largest citation database. Extracted data were analysed, and VOSviewer software was used to visualise trends. The result showed an increase in publications and citations in the past 20 years indicating the rising interest on heavy metal contamination in the Antarctic region. Based on the analysis of keywords, the publications largely discuss various types of heavy metals found in the Antarctic water and sediment. The analysis on subject areas detects multiple disciplines involved, wherein the environmental science was well-represented. The top countries and authors producing the most publication in this field were from Australia, China, Brazil and Chile. Numerous efforts have been exercised to investigate heavy metal pollution and its mitigation approaches in the region in the past decades. This paper not only is relevant for scholars to understand the development status and trends in this field but also offers clear insights on the future direction of Antarctic heavy metal contamination and remediation research.

Effect of elemental composition assigned to antrotopic pollution on the quality of the water and sediment of the Marrecas river (PR, Brazil) as highlighted by multivariate statistical analyses.

In recent years, several environmental pollutants have been monitored in surface waters and sediments. However, few studies apply multivariate statistics to identify the main components and correlate them temporally and spatially. In this sense, the present study sought to monitor the quality of water and sediments in the Rio Marrecas/Brazil, through the analysis of physicochemical parameters and trace elements, as well as to identifying sources of contamination, using multivariate statistics. For this purpose, sampling was carried out in nine locations for a period of 12 months. The Total Reflection X-ray Fluorescence (TXRF) technique was used to quantify the 15 elements identified in water and sediment samples. Through multivariate statistical analyses, the most significant elements, their correlations and possible pollutant sources were defined, and the pollution index (HPI) and assessment index (HEI) of heavy metals were applied. The parameters pH and BOD5 do not comply with Brazilian legislation. Based on PCA and Spearman correlation, there was strong evidence of contamination of the water naturally, composed of the elements Ti, V, Mn, Fe, and of anthropogenic origin composed of the elements Ca, Ni, Cu, Zn. These findings provide insights to determine the impacts of heavy metals on human health and the environment.

Phytoremediation of metals by colonizing plants developed in point bars in the channeled bed of the Dilúvio Stream, Southern Brazil.

Urban rivers are intensely impacted by pollution with metals resulting from anthropogenic activities, and these elements present in water and sediments can be ecofriendly phytoremediated. This study aimed to evaluate the levels of metals in the sediments and colonizing plants growing in point bars in the channeled bed of the Dilúvio Stream, Southern Brazil. Sediment and plants were sampled at five-point bars with consolidated vegetation. These point bars are formed mainly by sand, with increasing concentrations of clay plus silt, carbon, nitrogen, and metals (Zn, Cu, Cr, Ni, Pb, and Cd) downstream. The concentration of Zn (338 µg/g) and Cu (219 µg/g) in sediments were 1.6 and 1.11 above the probable effect level at the most downstream site. The translocation factor was low in all sites and for all potentially toxic metals evaluated (ranging from 0.01 to 0.63). However, bioaccumulation factor exhibited high values, especially for Cd (average of 2.51), Ni (1.62), Zn (1.49), and Cr (1.25), suggesting that the colonizing plants have more potential for phytostabilization and phytoaccumulation than phytoextraction. These plants can be considered as natural filtering reducing the environmental contamination and the flow of these contaminants in the drainage network. Statement of novelty: Colonizing plants growing in point bars of urban rivers are common around the world; however, their phytoremediation potential is poorly studied. Colonizing plants may be useful for phytoremediation of water, effluents, and sediments of the Dilúvio Stream (Southern Brazil), polluted by potentially toxic metals that originated from the urbanization.

Estimativa do número de amostras de solo para caracterizar elementos químicos utilizando fluorescência de raios X portátil em áreas contaminadas: estudo de caso em Resende / Estimation of the number of soil samples for characterization of chemical elements using portable X-ray fluorescence in contaminated areas: a case study in Resende

RESUMO A representatividade da amostragem é fundamental para embasar a tomada de decisão, uma vez que a heterogeneidade da matriz é o principal fator para incerteza dos dados nos estudos de gerenciamento de áreas contaminadas. Neste estudo, coletaram-se 112 amostras de solo superficial em malha quadrada de 1 x 1 m, em uma área 15 x 6 m, no campus regional de Resende da Universidade do Estado do Rio de Janeiro. Anteriormente, no terreno funcionaram empresas de produção de filmes radiográficos e purificação de prata metálica. As amostras de solo foram analisadas por pXRF, método de screening para metais. Com base nos dados levantados, calculou-se, por meio de métodos estatísticos, a quantidade de amostras que permitiriam uma caracterização representativa da área, considerando um erro relativo de 20% para dois intervalos de confiança: 95 e 80%. As análises indicaram concentrações superiores aos valores de referência para os parâmetros prata, mercúrio, chumbo, selênio e zinco. Os resultados de mercúrio possivelmente referem-se a ruído espectral, não estando relacionados ao histórico de uso e ocupação. Os coeficientes de variação das concentrações dos elementos analisados variaram de 132 a 225%. Considerando uma distribuição lognormal, calcularam-se 76 amostras para o maior intervalo de confiança e 53 para o menor. Isso seria o equivalente a transectos com espaçamentos de 1,47 e 2,11 m. Os resultados ratificam a necessidade de investigações de alta resolução nas áreas fonte, conforme recomendado pela Decisão de Diretoria da Companhia Ambiental do Estado de São Paulo nº 038/2017/C (DD-038).

ABSTRACT The representativeness of the sampling is fundamental to support decisions, since the heterogeneity of the matrix is the main factor for data uncertainty in contaminated areas management studies. In this study, 112 surface soil samples were collected in a square mesh of 1 x 1 m, in an area of 15 x 6 m, at the Campus Regional de Resende (CRR) of Universidade do Estado do Rio de Janeiro (UERJ). Previously, companies of radiographic films production and metallic silver purification operated in this area. The soil samples were analyzed by pXRF, a screening method for metals detection. Based on the data collected, the number of samples that would allow a representative characterization of the area was calculated, using statistical methods, considering a relative error of 20% for 80 and 95% confidence intervals. The analyses indicated concentrations higher than the reference values for the parameters silver, mercury, lead, selenium, and zinc. The results of mercury possibly refer to spectral noise, not being related to the history of use and occupancy. The coefficient of variation of the soil obtained ranged from 132 to 225%. Considering a lognormal distribution, 76 samples were calculated for the highest confidence interval and 53 for the lowest. This would be the equivalent of transects with spacings of approximately 1.47 and 2.11 m. The results confirm the need for high resolution investigations in the source areas, as recommended by the Executive Board Decision of CETESB No. 038/2017/C (DD-038).

Heavy metal pollution and health risk assessment of soils from open dumps in the Metropolitan Area of Buenos Aires, Argentina.

We assessed heavy metal pollution and potential health risk by ingestion of soil in six open dumps in the Metropolitan Area of Buenos Aires (MABA), Argentina. For the determination of Cd, Cu, Ni, Pb, Zn, Hg, and Cr, soil samples were taken from the first 10 cm using sampling grids installed between the boundaries of the waste final disposal sites and the beginning of the urban area. Soil samples were considered contaminated if at least one metal exceeded the maximum levels established by the Argentine regulation. Potential health risk by soil ingestion was calculated using deterministic analysis for both adults and children and stochastic analysis only for children. In 39.8% (N = 171) of the soil samples, the concentration of at least one metal was above the guide levels. Concentrations of Pb, Cu, and Zn exceeded maximum permissible values in all open dumps. Except for Hg, heavy metal concentrations differed significantly among open dumps. Hazard indexes > 1 were obtained for the children's population using both deterministic and stochastic models. The most sensitive variables in the stochastic model were exposure frequency and soil ingestion rate, together explaining 70% of the variation in the forecasts. The calculated risks were highly dependent on Pb concentrations. The determination of blood lead concentration in children and the assessment of other exposure routes are needed in areas of open dump influence in MABA.

Detection of sentinel bacteria in mangrove sediments contaminated with heavy metals.

Mangroves in the Northwest Coast of South America are contaminated with heavy metals due to wastewater discharges from industries, affecting the biota from this environment. However, bacteria proliferate in these harsh environmental conditions becoming possible sentinel of these contaminations. In this study, bacterial community composition was analyzed by throughput sequencing of the 16S rRNA gene from polluted and pristine mangrove sediments affected by marked differences in heavy metal concentrations. Core bacteria were dominated by Proteobacteria, Firmicutes, and Bacteroidetes phyla, with strong differences between sites at class and genus levels, correlated with metal levels. Increment of abundance on specific OTUs were associated with either elevated or decreased concentrations of metals and with the sulfur cycle. The abundance of Sulfurovum lithotrophicum, Leptolinea tardivitalis, Desulfococcus multivorans and Aminobacterium colombiense increases when metals rise. On contrary, Bacillus stamsii, Nioella nitrareducens and Clostridiisalibacter paucivorans abundance increases when metal levels are reduced. We propose these OTUs as bacterial sentinels, whose abundance can help monitor the restoration programs of contaminated mangrove sediments in the future.

Development and Evaluation of Copper Electrodes, Modified with Bimetallic Nanoparticles, to be Used as Sensors of Cysteine-Rich Peptides Synthesized by Tobacco Cells Exposed to Cytotoxic Levels of Cadmium.

We report on two new electrochemical sensors which, coupled to differential pulse voltammetry, constitutes a useful tool for diagnosis of heavy metal pollution. The electrochemical sensors AgHgNf/Cu and the AgBiNf/Cu were obtained by deposition of bimetallic particles of AgHg or AgBi on copper electrodes covered with a Nafion (Nf) film, respectively. Micrographs of the electrode's surface showed evenly scattered bimetallic particles, with an approximate diameter of 150 nm, embedded in the Nafion (Nf) film. In order to test the electrodes, the hydrogen evolution signal according to the Brdicka reaction was measured for the determination of cysteine-rich peptides (CRp) produced by plants. To check the accuracy of the electrodes, real samples of Nicotiana tabacum cells exposed to cytotoxic levels of cadmium were tested. The AgHgNf/Cu electrode produced detection limits (DLs) of 0.088 µmol L-1 for Cysteine and 0.139µmol L-1 for Glutathione, while for the AgBiNf/Cu electrode DLs were 0.41 µmol L-1 for cysteine and 0.244 µmol L-1 for glutathione. Thus, the new electrodes could be a useful analytical electrochemical system very convenient for fieldwork. The electrodes were capable of direct, accurate, and sensitive detection of synthesized peptides, despite the complex matrix where the Nicotiana tabacum cells were grown.

Characteristics of groundwater discharge to river and related heavy metal transportation in a mountain mining area of Dabaoshan, Southern China.

Groundwater discharge to river and the related heavy metal transportation were estimated for Dabaoshan, a mountain mining area where extensive mining activities had been conducted over 40 years. In the lower reach of the mining area, shallow aquifers were contaminated by varies heavy metals due to the discharge of acid mine drainage. Polluted aquifers act as long-term pollution sources to the surrounding gaining rivers, even after the mining activities were stopped. The natural tracer 222Rn was measured for river water of the Hengshi River and groundwater adjacent to the river channel in both wet and dry seasons. The total groundwater discharge rate was estimated to be 17.4-26.7 × 103 m3 day-1 in wet season and 1.9-2.1 × 103 m3 day-1 in dry season; and the river recharge was 5.6 ±â€¯1.0 × 103 m3 day-1 in wet season and 2.1 ±â€¯1.0 × 103 m3 day-1 in dry season. Compared with other mining and natural/artificial factor influenced areas, groundwater discharge rate in Dabaoshan was much lower, but the magnitudes of groundwater-borne Cu, Zn, Mn and Co fluxes were comparable or even much higher. This suggested that groundwater-derived heavy metal fluxes were significant pollution sources to river in the mountain mining area. Meanwhile, the results also suggested that concentrations of Cd, Pb, Cu, Ni, Mn, Fe, Zn and Tl in groundwater increased where the recharge of river water to groundwater occurred, suggesting the recharge of river water can affect heavy metal concentrations of the beneath aquifers, even in a gaining river.

HHRISK: A code for assessment of human health risk due to environmental chemical pollution.

Chemical environmental pollution is currently one of the most concerning environmental problem on a global scale, due to the high risks posed to ecological systems and human health. Risk assessment methodologies are valuable tools for preventive management and the mitigation of human health risks. However, the application of these methodological tools involves several steps and the knowledge of many variables, which can hinder its correct implementation. The main objective of this work was the development of the computational code for human health risk assessment: HHRISK (Human Health Risk). This code allows for an agile and accurate risk assessment based on the methodology established by the U.S. Environmental Protection Agency (U.S. EPA). Different from other published methods, the HHRISK code includes a new spatiotemporal matrix for the analysis of the aggregated risk (for multiple exposure pathways) and the cumulative (for exposure to multiple chemicals). HHRISK was applied to two case studies published dealing with the assessment of risk to human health through exposure to toxic metals, obtaining satisfactory results. The concordance between the average results obtained with the HHRISK and those reported by the authors confirm the validity of the implemented model. The inclusion of a greater spatiotemporal detail of the risks allowed to carry out a more accurate analysis and to propose new subsidies for a more efficient risk mitigation management by affected place and period of time.

Arsenic and lead contamination in soil and in feathers of three resident passerine species in a semi-arid mining region of the Mexican plateau.

The current study aimed at quantifying arsenic and lead in feathers from three passerine species that are residents from areas exposed to mining activities (Toxostoma curvirostre, Campylorhynchus brunneicapillus, and Melozone fusca). Lead and As contents in bird feathers and in superficial soil samples were measured with AAS. Levels of these metals were compared between sites exposed and unexposed to mining. Possible correlations of As and Pb between superficial soil and bird feathers were also investigated. Soil metal concentrations were significantly higher near mining sites, and metal concentrations in bird feathers showed a behavior similar to those recorded for soil samples. Individual birds from polluted sites had higher mean feather metal concentrations in comparison with non-polluted sites; no differences in metal concentrations were recorded among bird species. This work constitutes a basis for monitoring contaminants, and for future toxicological studies attempting to understand the impact that some mining activities may have on bird populations.

Hematological parameters in Nile Tilápia, Oreochromis niloticus exposed to sub-letal concentrations of mercury

Mercury toxicity in tilapia, Oreochromis niloticus, (Linnaeus, 1758) was investigated by the hematological parameters after long-term (14 days) exposure to various Hg concentrations (0.02, 0.002, 0.0002mg/L Hg). Test groups were set up with three replicates for each concentration, plus the control group. Blood samples were collected from six individuals for each concentration at 0, 3, 7, 10 and 14 days of exposure. The hematological parameters analyzed were: total red blood cell count (RBC), hemoglobin concentration (Hb), hematocrit (Ht), mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), total white blood cell count (WBC) and differential leukocyte counts and total thrombocyte count (Tr). There were no significant differences among the mean hematological values at the different Hg concentrations indicating that Hg at the concentrations studied was not toxic to tilapia.

A toxicidade do mercúrio foi avaliada em tilápia, Oreochromis niloticus (Linnaues, 1758) através da análise dos parâmetros hematológicos após exposição a diferentes concentrações sub-letais, durante um período de 14 dias. O bioensaio foi conduzido no laboratório de toxicologia do Instituto de Pesca, SP. Foram utilizados alevinos (12.44 ± 0.84 cm, e 27.13 ± 4.67 g) e aquários com capacidade para 50 litros e preenchidos com água declorada e mais a quantidade de solução de mercúrio (HgCl2) correspondendo as seguintes concentrações: 0,02; 0,002; 0.0002 mg.L-1 Hg. Foram utilizadas 3 repetições de cada concentração e grupo controle. Amostras de sangue foram coletadas de seis animais de cada concentração nos tempos 0, 3, 7, 10 e 14 dias de exposição. Foram avaliados: a contagem de eritrócitos (RBC), concentração de hemoglobina (Hb), hematócrito (Ht), volume corpuscular médio (VCM), hemoglobina corpuscular média (HCM) e concentração de hemoglobina corpuscular média (CHCM), trombócitos totais (Tr), contagem diferencial e total de leucócitos (Lc). Os resultados demonstram que as concentrações de Hg testadas, não alteraram significativamente os parâmetros hematológicos, permitindo concluir que a quantidade de Hg na água não foram suficientes para afetar o quadro hematológico de Oreochromis niloticus.