Suchergebnisse

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.

Le colloque Communication environnementale en République Démocratique du Congo : enjeux et perspectives, à l'origine cette publication, a offert à ses participants une vision large de la situation environnementale en RDC, en partant des cas d'impact humain sur l'environnement et les ressources naturelles (qualité de l'eau et des sols, pollution par des déchets, menace sur la biodiversité), en passant par le gestion environnementale, pour aboutir à la question essentielle en matière de politique de développement durable, soit celle de la communication et de l'éducation.

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.

Large sub-Saharan African cities are characterized by serious and persistent environmental problem of Solid Waste Management (SWM). The city of Kinshasa, in Democratic Republic of the Congo has a long lasting and major concern of SWM. More worryingly, with rapid population growth and urbanization, waste generation, both domestic and industrial, is expected to rise with great potential of health and environmental problems. Therefore, with an objective of bringing a possible solution that reduces the increasing problem of SWM, we explore in the present study the use of crowdsourcing as a possible mechanism to identify, localize, characterize solid waste landfills. The proposed approach allows (i) creating a spatial and temporal database through a participatory process to support data collection and information generation, and (ii) visualizing the spatial and temporal distribution of observations through an interactive map. Our database holds 187 observations of solid waste disposals across Kinshasa within two years with estimated volume of solid waste accounts of 587'920 m3. These observations include 61 public disposals (e.g., transit center), and 151 wild dumps, of which, 174 active and 3 inactive disposals. The approach developed in this study is a proof-of- concept and a successful implementation was achieved. Our conception and results provide new tool and mechanism to collect data and generate useful information on solid waste landfills in the city of Kinshasa that was not available before. The results of this study indicate that crowdsourcing can be a valuable mechanism to involve citizens in collecting data on solid waste landfills in the city of Kinshasa, which can be applied in similar urban cities.

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, ...

The accumulation of toxic metals in food consumption has been identified as a serious human health risk. Ledermanniella schlechteri (LDMSC) is a genus of Podostemaceae plant family and is well known to grow naturally on rocks of rapid waters. LDMSC is rich in nutrients and one of the most consumed aquatic vegetables in Africa. However, there are not any studies performed to assess the level of toxic metals in this aquatic plant. Consequently, the aim of this study is to assess the concentration of toxic metals in LDMSC and to evaluate the potential health risk to the consumers. Plant samples were collected in Congo River at the rapid of Kinsuka-Mimosa, in the vicinity of Kinshasa, Capital City of the Democratic Republic of the Congo (DRC). Toxic metal (Cr, Cu, Zn, As, Cd and Pb) concentrations in LDMSC were determined using Inductively Coupled Plasma Mass Spectrometry whereas Hg analysis was performed using atomic absorption spectrophotometry. Metal levels in LDMSC were compared with international regulation for human consumption set by the Food and Agriculture Organization (FAO) and World Health Organization (WHO). Metal concentrations in LDMSC varied significantly according to sampling sites. The average values (in mg kg-1) ranging from 0.44 -9.1 (Cr), 0.14-4.52 (Ni), 5.5-78.4 (Cu), 336.14-1520.91 (Zn), 0.08-0.49 (As), 0.21-0.78 (Cd), 0.44-11.81 (Pb), and 0.02-0.24 (Hg). In all sampling sites, the average concentration of Zn, As, Cd, and Hg in plant samples exceeded the FAO/WHO permissible limits for human consumption. According to FAO/WHO regulation and the calculated values of targeted risk quotient, the impact on human health is likely to occur. On other hand, according to the metal levels in LDMSC, this plant can be used as bioindicator to evaluate the state of river pollution by toxic metals.

Oysters and shrimp are abundant and commonly consumed seafood by the indigenous population of the Kongo central region of the Democratic Republic of the Congo (DRC). Literature reviews suggest that no data were available for the metal concentrations in these species. Consequently, the purpose of this study is to determine the metal concentrations in tissues of oysters (Egeria congica) and shrimp (Macrobrachium spp., Parapenaeus spp., Penaeus spp.) collected in November 2017 from the Atlantic Ocean Coast of DRC in the territory of Muanda. Metal levels in the seafood species studied here were put into context using international regulation for human consumption set by the Food and Agriculture Organization (FAO), Canadian Food Inspection Agency (CFIA), European Union (EU), and World Health Organization (WHO). Our results demonstrated that the concentration of heavy metals varied considerably between sampling sites and analyzed species (P<0.05), with the values (in mg kg1) ranged between 0.05-0.41, 0.03-2.25,

In many suburban municipalities of developing countries, the household drinking water comes mainly from groundwater including, wells, streams and springs. These sources are vulnerable because poor hygienic conditions and sanitation prevail causing persistence and recurrent waterborne diseases. In this research, a survey study on water resource use and an epidemiological survey of waterborne diseases were conducted among users of water points and medical institutions in suburban communes of Selembao and Kimbanseke (Kinshasa, the Democratic Republic of the Congo). In addition, physicochemical (temperature, pH, O 2 , electrical conductivity, and soluble ions: Na + , K + , PO 4 3− , SO 4 2− , NO 3 − , NO 2 − ) and bacteriological (FIB: faecal indicator bacteria) analyses of water from 21 wells and springs were performed according to the seasonal variations. FIB included Escherichia coli ( E. coli ), Enterococcus and Total Coliforms. The survey results indicate that more than 75% of the patients admitted to local medical institutions between 2016 and 2019 are affected by waterborne diseases, including typhoid fever, amoebic dysentery, diarrhoea, gastroenteritis disorders and cholera. Except for NO 3 − in some sites, the water physicochemical parameter values are within WHO permissible limits for drinking/domestic water quality. On the contrary, the results revealed high FIB levels in water from unmanaged wells and springs during rainy and dry seasons. The microbiological pollution was significantly higher in the rainy season compared to the dry season. Interestingly, no FIB contamination was observed in water samples from managed/developed wells. The results from this study will guide local government decisions on improving water quality to prevent recurrent waterborne diseases.

The objective of the present research was to evaluate the contamination level and potential risks at a part of a large and important river in Central Africa, the Congo River. Surface sediments were collected from seven stations located in Maluku-Kinsuka section, at the vicinity of Kinshasa, capital city of Democratic Republic of the Congo. The concentration of toxic metals (Cr, Co, Ni, Cu, Zn, As, Cd and Pb) in sediment samples were determined using Inductive Coupled Plasma-Mass Spectroscopy (ICP-MS). The Hg analysis was carried out using Advanced Mercury Analyzer (AMA). The evaluation of the pollution degree was based on Sediment Quality Guidelines (SQGs), Enrichment Factor (EF), Geoaccumulation Index (Igeo), and using toxicity test based on exposing Ostracods to the sediment samples. The result revealed high metal concentrations in sediments from the 4 densely populated areas (Kinkole, Kauka fishermen, Demoulin, Chanic), reaching the values (mg kg-1) of of 95.5, 14.3, 37.1, 139.9, 281.5, 4.8, 6.6, 200.9 and 4.9 mg kg-1 for Cr, Co, Ni, Cu, Zn, As, Cd, Pb and Hg, respectively. These values are above SQGs and probable effect levels. In these sites, Igeo and EF values showed heavily to extremely polluted and severe enrichment to extremely severe enrichment for analysed metals. Additionally, Ostracods exposed to sediments resulted in 100% mortality rates after 6 days of incubation, demonstrating the sediment toxicity as well as potential risks for aquatic living organisms. The pollution in these sites may be explained by local intense human activities with various commercial, presence of uncontrolled landfills in riverbank and industrial settlements, as well as by the construction of boats for the regular navigation along the river. This research presents useful tools for evaluating sediments quality and risk, which can be applied to similar environments.

The urban agriculture in developing countries plays a huge important socioeconomic role in confronting the challenge of eradicating hunger, improving food security and the social daily life of the population. However, the quality evaluation of water used for urban agriculture irrigation as well as the accumulation of pollutants such as heavy metals in fresh produces are still largely unstudied. The purpose of this study was to investigate the concentration of metals (Cr, Co, Ni, Cu, Zn, As, Cd, Pb and Hg) in irrigation water from rivers, soil and Amaranthus viridis (A. viridis), in order to evaluate the potential human dietary risks. The research was conducted in eight sites characterized by intensive agriculture performed in watersheds in Kinshasa, capital of Democratic Republic of the Congo. The results showed high metal concentrations in A. viridis leaf varying considerably among sampling sites (P<0.05), reaching the values (in mg kg-1 wet weight) of 2.97 (Cr), 1.73 (Co), 12.30 (Ni), 16.11 (Cu), 652.91 (Zn), 0.10 (As), 1.62 (Cd), 8.91 (Pb), and 0.1 (Hg). These values exceeded safe limits set by Food and Agriculture Organization/World Health Organization for human consumption (WHO/FAO) for human consumption. The assessment of human health risks using the targeted risk quotient and estimated dietary intake showed potential health hazards to consumers due to the levels of Cd and Pb in leafy vegetables from several studied sites. The vegetable contamination can be explained by chemicals used to combat and prevent A. viridis diseases, and the vehicle and motorcycle emissions around. Thus, given the concentrations of metals in A. viridus leaf, human health implications are likely to occur on heavy continuous consumption.

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.

Microbial and toxic metals contamination of freshwater resources is still a major problem in many parts of the world. In this study, water and sediment samples (n=9) were subjected to the microbiological and some physicochemical analysis to assess the water quality of the N'Djili River (Kinshasa, Democratic Republic of Congo). Microbiological analysis was performed for faecal indicator bacteria (FIB) including Escherichia coli (E. coli) and Enterococcus (ENT). The FIB characterization was performed for general E. coli, Enterococcus faecalis (E. faecalis) and human-specific bacteroides by PCR, using specific primers. The physicochemical parameters including pH and electrical conductivity were measured in water samples, and grain size distribution, organic matter and total mercury (Hg) were measured in sediments samples. The results revealed high concentration of FIB, with the maximum values of 1.6x103 and 2.7x103 CFU 100 mL-1 for E. coli and ENT, respectively. The FIB in sediment samples present higher concentration than in water, with maximum values of 9.4x105 and 1.2x105 for E. coli and ENT, respectively. The PCR assays for human-specific bacteroides HF183/HF134 indicated that more than 90% of bacteria were from human origin. The Hg concentration in sediment samples reaches the values of 0.5 mg kg-1. Thus, our results indicate that the uncontrolled landfills and mixing of untreated urban and industrial effluents lead to the deterioration of the water quality of the rivers traversing the economically important cities. This study represents useful tools incorporated to evaluate water and sediment quality in river systems which can be applied to similar aquatic environments.

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.