Suchergebnisse

The pollution of water is a major problem in many parts of the world. In many developing countries, aquatic systems are receiving untreated or partially treated effluents, containing anthropogenic pollutants whereas these rivers serve as a basic network for human and animal consumption. High values of toxic metals, persistent organic pollutants (POPs), faecal indicator bacteria (FIBs), antibiotic resistant bacteria (ARBs) and antibiotic resistance genes (ARGs) in rivers may pose a great risk to human health and aquatic living organisms. The main objective of the research is to assess the prevalence and dissemination of toxic metals, POPs, FIB, ARB and ARGs in the rivers of Kinshasa (Republic Democratic of the Congo) as a study case. Overall, the present work demonstrated that chemical and microbiological pollution can exceed, in many studied sites, the international recommendation for water quality and has the potential to affect ecosystem functions as well as human impact.

Antibiotic resistant bacteria and genes which confer resistance to antibiotics from human/animal sources are currently considered a serious environmental and a public health concern. This problem is still little investigated in aquatic environment of developing countries according to the different climatic conditions. In this research, the total bacterial load, the abundance of relevant bacteria (Escherichia coli (E. coli), Enterococcus (Ent), and Pseudomonas), and antibiotic resistance genes (ARGs: blaOXA-48, blaCTX-M, sul1, sul2, sul3, and tet(B)) were quantified using Quantitative Polymerase Chain Reaction (qPCR) in sediments from two rivers receiving animal farming wastewaters under tropical conditions in Kinshasa, capital city of the Democratic Republic of the Congo. Human and pig host-specific markers were exploited to examine the sources of contamination. The total bacterial load correlated with relevant bacteria and genes blaOXA-48, sul3, and tet(B) (P value<0.01). E. coli strongly correlated with 16s rDNA, Enterococcus, Pseudomonas spp., blaOXA-48, sul3, and tet(B) (P value<0.01) and with blaCTX-M, sul1, and sul2 at a lower magnitude (P value <0.05). The most abundant and most commonly detected ARGs were sul1, and sul2. Our findings confirmed at least two sources of contamination originating from pigs and anthropogenic activities and that animal farm wastewaters didn't exclusively contribute to antibiotic resistance profile. Moreover, our analysis sheds the light on developing countries where less than adequate infrastructure or lack of it adds to the complexity of antibiotic resistance proliferation with potential risks to the human exposure and aquatic living organisms. This research presents useful tools for the evaluation of emerging microbial contaminants in aquatic ecosystems which can be applied in the similar environment.

AbstractThe co-occurrence of heavy metals, antibiotic-resistant bacteria (ARB) and antibiotic-resistance genes (ARGs) from hospital effluents spreading into the river receiving systems and evaluating associated risks are topics of scientific interest and still under-studied in developing countries under tropical conditions. To understand the selectors of the ARGs, we examined the occurrence of heavy metals (Cr, Co, Ni, Cu, Cd, Pb and Zn), associated ARB (β-lactam-resistant Escherichia coli, β-lactam-resistant Enterobacteriaceae, and carbapenem-resistant Enterobacteriaceae) and ARGs (blaOXA, blaCTX-M, blaIMP, blaTEM) in water and sediments from two sub-urban rivers receiving urban and hospital effluent waters in the Democratic Republic of the Congo (DRC). High abundances of ARB and ARGs were observed in all sediment samples. All the metal contents correlated negatively with grain size (− 0.94 ≤ r ≤  − 0.54, p < 0.05) except for Ni and positively with organic matter content and total copies of 16 s rRNA (0.42 ≤ r ≤ 0.79, p < 0.05), except for Ni and Zn. The metals had a significant positive correlation with the faecal indicator Enterococcus except for Ni and Cd (0.43 ≤ r ≤ 0.67, p < 0.05). Carbapenem-resistant Enterobacteriaceae correlated negatively with Zn (r =  − 0.44, p < 0.05) and positively with all the rest of toxic metals (0.58 ≤ r ≤ 1.0, p < 0.05). These results suggested that some metals had a great influence on the persistence of ARB and ARGs in sediments. Overall, this study strongly recommends the managing urban wastewater to preserve water resources used for human and agricultural purposes. Additionally, we recommend the utilizing biological indicators (faecal indicator bacteria, ARB, ARGs) when investigating urban wastewater pollutions.

The co-occurrence of heavy metals, antibiotic-resistant bacteria (ARB) and antibiotic-resistance genes (ARGs) from hospital effluents spreading into the river receiving systems and evaluating associated risks are topics of scientific interest and still under-studied in developing countries under tropical conditions. To understand the selectors of the ARGs, we examined the occurrence of heavy metals (Cr, Co, Ni, Cu, Cd, Pb and Zn), associated ARB (β-lactam-resistant Escherichia coli, β-lactam-resistant Enterobacteriaceae, and carbapenem-resistant Enterobacteriaceae) and ARGs (bla(OXA), bla(CTX-M), bla(IMP), bla(TEM)) in water and sediments from two sub-urban rivers receiving urban and hospital effluent waters in the Democratic Republic of the Congo (DRC). High abundances of ARB and ARGs were observed in all sediment samples. All the metal contents correlated negatively with grain size (− 0.94 ≤ r ≤ − 0.54, p < 0.05) except for Ni and positively with organic matter content and total copies of 16 s rRNA (0.42 ≤ r ≤ 0.79, p < 0.05), except for Ni and Zn. The metals had a significant positive correlation with the faecal indicator Enterococcus except for Ni and Cd (0.43 ≤ r ≤ 0.67, p < 0.05). Carbapenem-resistant Enterobacteriaceae correlated negatively with Zn (r = − 0.44, p < 0.05) and positively with all the rest of toxic metals (0.58 ≤ r ≤ 1.0, p < 0.05). These results suggested that some metals had a great influence on the persistence of ARB and ARGs in sediments. Overall, this study strongly recommends the managing urban wastewater to preserve water resources used for human and agricultural purposes. Additionally, we recommend the utilizing biological indicators (faecal indicator bacteria, ARB, ARGs) when investigating urban wastewater pollutions. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s11356-021-17115-z.

The co-occurrence of heavy metals, antibiotic-resistant bacteria (ARB) and antibiotic-resistance genes (ARGs) from hospital effluents spreading into the river receiving systems and evaluating associated risks are topics of scientific interest and still under-studied in developing countries under tropical conditions. To understand the selectors of the ARGs, we examined the occurrence of heavy metals (Cr, Co, Ni, Cu, Cd, Pb and Zn), associated ARB (β-lactam-resistant Escherichia coli , β-lactam-resistant Enterobacteriaceae, and carbapenem-resistant Enterobacteriaceae) and ARGs ( bla OXA , bla CTX-M , bla IMP , bla TEM ) in water and sediments from two sub-urban rivers receiving urban and hospital effluent waters in the Democratic Republic of the Congo (DRC). High abundances of ARB and ARGs were observed in all sediment samples. All the metal contents correlated negatively with grain size (− 0.94 ≤ r ≤ − 0.54, p < 0.05) except for Ni and positively with organic matter content and total copies of 16 s rRNA (0.42 ≤ r ≤ 0.79, p < 0.05), except for Ni and Zn. The metals had a significant positive correlation with the faecal indicator Enterococcus except for Ni and Cd (0.43 ≤ r ≤ 0.67, p < 0.05). Carbapenem-resistant Enterobacteriaceae correlated negatively with Zn ( r = − 0.44, p < 0.05) and positively with all the rest of toxic metals (0.58 ≤ r ≤ 1.0, p < 0.05). These results suggested that some metals had a great influence on the persistence of ARB and ARGs in sediments. Overall, this study strongly recommends the managing urban wastewater to preserve water resources used for human and agricultural purposes. Additionally, we recommend the utilizing biological indicators (faecal indicator bacteria, ARB, ARGs) when investigating urban wastewater pollutions.

The contamination of food chain by toxic metals constitutes a major concern worldwide because of human health potential risks. Amaranthus viridis (A. viridis) is one of the most consumed vegetables in South Asian and Sub-Saharan African countries. However, the accumulation of pollutants, such as toxic metals in this plant is still little investigated. Consequently, this research investigates the level of toxic metals in A. viridis collected from four major markets of Kinshasa, Capital City of the Democratic Republic of the Congo, according to the seasonal variation in order to determine potential health risk for the consumers. The results revealed high metal concentrations in edible leaf vegetables during both dry and wet seasons. Metal concentration reaching the values (in mg kg-1) of 3.6 (Cr), 1.5 (Co), 29.7 (Cu), 348.2 (Zn), 1.7 (As), 1.5 (Cd), 18.3 (Pb) and 0.2 (Hg). Except for Cu, the analyzed metal concentrations in leafy vegetables exceeded the permissible levels set by Food and Agriculture Organization/World Health Organization (FAO/WHO) for human consumption. Given the level of toxic metals in A. viridis leaf according to the regulation of FAO/WHO, human health consequences are likely to occur on continuous vegetable consumption. Our results recommend implementation of measures and efforts to improve the quality of this most consumed vegetable in order to minimize potential health risk for the consumers.

Data concerning the occurrence of emerging biological contaminants such as antibiotic resistance genes (ARGs) and fecal indicator bacteria (FIB) in aquatic environments in Sub-Saharan African countries is limited. On the other hand, antibiotic resistance remains a worldwide problem which may pose serious potential risks to human and animal health. Consequently, there is a growing number of reports concerning the prevalence and dissemination of these contaminants into various environmental compartments. Sediments provide the opportunity to reconstruct the pollution history and evaluate impacts so this study investigates the abundance and distribution of toxic metals, FIB, and ARGs released from hospital effluent wastewaters and their presence in river sediments receiving systems. ARGs (blaTEM, blaCTX-M, blaSHV, and aadA), total bacterial load, and selected bacterial species FIB (E. coli, Enterococcus (ENT)) and Pseudomonas species (Psd) were quantified by targeting species specific genes using quantitative PCR (qPCR) in total DNA extracted from the sediments recovered from 4 hospital outlet pipes (HOP) and their river receiving systems in the City of Kinshasa in the Democratic Republic of the Congo. The results highlight the great concentration of toxic metals in HOP, reaching the values (in mg kg-1) of 47.9 (Cr), 213.6 (Cu), 1434.4 (Zn), 2.6 (Cd), 281.5 (Pb), and 13.6 (Hg). The results also highlight the highest (P˂0.05) values of 16S rRNA, FIB, and ARGs copy numbers in all sampling sites including upstream (control site), discharge point, and downstream of receiving rivers, indicating that the hospital effluent water is not an exclusive source of the biological contaminants entering the urban rivers. Significant correlation were observed between (i) all analyzed ARGs and total bacterial load (16S rRNA) 0.51 to 0.72 (p<0.001, n=65); (ii) ARGs (except blaTEM) and FIB and Psd 0.57 < r < 0.82 (p<0.001, n=65); and (iii) ARGs (except blaTEM) and toxic metals (Cd, Cr, Cu, and Zn) 0.44 to 0.72, (p<0.001, ...

Water resource contamination is still a major concern in several regions of developing countries especially in sub-Saharan countries in which polluted waters pose serious risks to human health and the environment. The seasonal variation of the physicochemical parameters including pH, electrical conductivity (EC), dissolved oxygen (O2), dissolved organic carbon (DOC), total organic carbon (TOC), and trace metals were assessed in water samples collected from wells (n=3) and two rivers which were the River Lukemi (RLK, n=3) and River Luini (RLN, n=2) located in the City of Kikwit (Province of Kwilu, Democratic Republic of the Congo). Samples were collected during the dry and wet seasons. The concentration of trace metals (Cr, Mn, Co, Ni, Cu, Zn, As, Mo, Ag, Cd, Sn, Sb, and Pb) in water was measured using Inductively Coupled Plasma Mass Spectrometry (ICP-MS), and soluble ions (Na+, K+, NH4+, SO42-, NO3-, and Cl-) analysis was performed using Ion Chromatography. The results indicate the seasonal difference in the physicochemical composition of water e.g., the pH was lower in the wet compared to the dry season. pH values during the wet season ranged from 4.12 to 5.60 in wells and from 5.55 to 6.31 in rivers while the dry season values ranged from 6.27 to 6.98 in wells and from 7.09 to 7.44 in rivers. The concentrations of soluble ions and other physicochemical parameters (O2, DOC, and TOC) also varied with the seasons, being higher in the wet and lower in the dry season. With the exception of Mn, the average concentrations of other trace metals measured in water samples from wells and rivers met the World Health Organization (WHO) guidelines for drinking/domestic water quality. Mn concentration in water samples analysed ranged between 634 and 812 and 1352 to 1741 µg L-1 during the dry and wet seasons, respectively. These results imply that the high concentration of Mn in the water samples may be explained by the geological origin and result of natural weathering processes. In general, according to the parameters analysed, the water samples taken from the sites studied in both seasons appear to meet drinking water standards according to the WHO guidelines but with the two exceptions of the pH and Mn. This study is important for the present situation and can be applied in similar environmental compartments in the future to assess the availability of safe drinking water in developing countries.

The contamination of freshwater resources with various organic and inorganic contaminants is still a major problem in many parts of the world, especially in developing countries in which the poor water quality continues to pose a serious threat to human health. In this study, the assessment of groundwater quality was performed in the municipality of Bumbu (Kinshasa, Democratic Republic of the Congo) according to the seasonal variation. Water physicochemical parameters [pH, electrical conductivity (EC), dissolved oxygen and soluble ions (Na+, K+, PO4 3-, SO4 2-, NO3-, NO2-)] and faecal indicator bacteria (FIB) including Escherichia coli (E. coli), Enterococcus (ENT) and Total coliforms (TC) were analysed. Except for EC and NO3, the results revealed low concentration of other water physicochemical parameters, which are below the recommended limits, according to World Health Organization guideline for drinking water. Additionally, the result showed high concentration of FIB reaching the values of 1.6 9 104, 1.5 9 104 and 9.0 9 105 CFU 100 mL-1 for E. coli, ENT and TC, respectively. The pollution was substantial in wet season compared to dry season. PCR amplification for human-Bacteroides indicated that more than 90 % of bacteria were from human origin. Our results highlight the potential human risk associated with the exposure to water contamination from wells due to the high level of NO3 -, EC, E. coli and ENT in both dry and wet seasons. The approach developed in this study helps provide a better understanding of the physicochemical and microbiological pollution of wells in large cities characterized with lack of wastewater and sanitation facilities.