The water pipe materials used by Regideso may alter the quality of the water supplied. The overpopulation of

displaced persons' sites has led to a disorder within these sites, manifested by the pollution of drinking water.

TDS (272.8 and 37.525 ppm) and conductivity (384.6 and 53.34 μs/cm) in well water than in Regideso water.

However, these parameters remain within the norm. The following TMEs values were obtained from Regideso

and well water: Chromium with mean concentrations of 0.0436 and 0.0482 mg/L, Copper with mean values of

0.1 and 0.124 mg/L, Silver with mean concentrations of 0.0064 and 0.0326 mg/L, and Nickel with mean values

of 0.0566 and 0.0656 mg/L. Generally, the concentrations of trace metal elements remain within the norm, such

as [Copper <0.28 mg/L, Silver <0.056 mg/L and Chromium <0.064 mg/L], yet the concentration of [Nickel

<0.082 mg/L] appears very high in these different waters. Above all, there is a high concentration of the metal

Silver in the well water. Hence the contribution of these pollutants to the pollution of ground water, which

undergoes no prior treatment before use.

Keywords- Determination, Trace metal elements (TMEs), Regideso, Wells waters, Bunia

(Kayalato et al., 2014; OCHA, 2023; Onivogui et al., 2013).

Inter-ethnic violence in Ituri has forced several thousand people to flee their homes, mainly in the territories of

Djugu, Irumu, and Mahagi, bringing the total number of internally displaced persons in the province to 1.2

million, according to OCHA. Of these, 227,000 live in 87 sites managed by UNHCR and IOM, while the majority

are staying with host families in communities that already have limited resources. The overcrowding of

displacement sites has resulted in disorder, as evidenced by the pollution of drinking water (OCHA, 2023;

UNHCR DRC, 2019).

It is a fact that trace metal elements are present in soils in several fractions of the solid phase and can be measured

by selective sequential dissolution (Ahoussi et al., 2012; Gove et al., 2001).

The increase in the flow of these trace metals into the soil is due to intense human activity at residential sites.

is lead. It is an established fact that these were widely used in public connections and private indoor plumbing.

They release lead into the water, affecting the nervous system of the population when found in excessive doses

(Balloy Mwanza et al., 2019; Veena et al., 1997).

We know that physicochemical analyses of certain parameters carried out by predecessors like TSANDIA,

MERUMBE, and GAKERI show that the water from these sources is definitely substandard (Balloy Mwanza et

al., 2019; Dégbey et al., 2008).

Therefore, the main question that prompted us to conduct this study was whether the water supplied by Regideso

and from wells in the city of Bunia contains trace amounts of metals and, if so, what the levels would be.

Furthermore, since those responsible for these water sources do not carry out this analysis, the population

believes that they are not affected by these pollutants because their effects are felt in the long term (Dahmana et

The city of Bunia is located in the Democratic Republic of Congo, in the Ituri province, in the northeast of the

country, at 1° 33' 52" East and 30° 14' 24" Northern latitudes. The average altitude is 1,250 m and the rainfall is

1,000 to 1,200 mm/year. The surface area of the island is precisely 830 km², as illustrated in Figure 1 below.

Fig. 1. Map of Bunia city showing its waterways and Neighbourhoods (Source: QGIS, 2020).

The following locations were targeted for sampling to perform these analyses:

• For Regideso:

- Treatment plant (Saïo Neighbourhood): where two samples were taken, one for treated water (site 1) and

- Kigonze displacement site (site 6).

- ISP/Bunia displaced persons site (site 7).

- HGR/Bunia displaced persons site (site 8).

- Mr. Richard Lombu's well in HGR/Bunia (site 9).

- Mr. Shako's well near Radio Candip (site 10).

All samples were taken at the beginning of October, specifically on the afternoon of 5 October 2020, for

Regideso and well water.

Half-litre polyethylene bottles were used, washed and rinsed with demineralised water beforehand. The samples

Mudzipela, Bigo, and Kolomani in the city of Bunia.

The use of a nonparametric statistical test made it possible to evaluate the average between the values obtained.

A nonparametric test is a test based on the study of the ranks of observations that do not make any particular

assumptions about the shape of the original distribution (nonparametric). The use of the F

R

and T

on the distribution range was useful for this purpose (Skoog et al., 2002; Conover, 1999).

Past and Excel 2013 software were used for the rapid statistical processing of this data. Then, OriginPro 2015

was used to plot the graphs presented in this paper.

transported to the OCC (Office Congolais de Contrôle)/Bunia laboratory for analysis. The samples were then

analyzed in accordance with the methodology specified by HANNA Instrument (Hanna Instruments, 2019).

Tables 1, 2 and Figure 3 present the results of the analysis of the physico-chemical parameters of well water and

Regideso water.

Table 1. Values of in situ physico-chemical parameters at Regideso sites.

Table 1 shows that the values of the physicochemical parameters (pH, temperature, conductivity, TDS, and

salinity) are lower in Regideso waters. Site (5) has high conductivity, TDS, and salinity values, while site (2)

has low values. The variations in pH and temperature are negligible.

Table 2. Values of in situ physico-chemical parameters of well water.

Table 4. Trace metal content in well water in mg/L

Table 5 shows that there is a significant difference between the averages of the following physical parameters:

conductivity, TDS, and salinity; and, at the level of a single TME, silver, which is more abundant in well water

than in Regideso spring water. Furthermore, the F

R

test indicates that the accuracies differ in the parameters: pH,

conductivity, salinity, and TDS, and elsewhere, it remains the same.

Table 6. T

d

standard.

Table 6 shows that, on the one hand, there is a significant difference between the standard values and the mean

values of the following parameters and TMEs: temperature, copper, and nickel; and, on the other hand, there

appears to be no significance between pH, chromium, and silver.

It is important to note that temperature variations diminish beyond a depth of 3 metres and that the temperature

of groundwater remains constant throughout the year (Petit & Erpicum, 1987). The temperature study showed

that the values obtained at the various sites range from 22.8°C to 25.4°C. The highest value was recorded at site

(8), while the lowest value was recorded at site (2). It is clear that the values for this parameter at sites (3) and

(8) are above 25°C, which is the reference value for drinking water quality (Chapman, 1996). It is clear that

these values are consistent with those of our predecessors, which ranged between 23.2

0

C (Rodier,

2009).

The conductivity values of the 10 sites vary from one site to another. The range is from 41.4 μs/cm to 490 μs/cm,

with the maximum recorded at site (9) and the minimum at site (2). The relationship between mineralization

previously. Generally, these salts come mainly from the erosion of lithosphere rocks by runoff and groundwater

(Ghazali & Zaid, 2013). The salinity study showed that the values obtained are less than 1 g/L, meaning that all

these waters are fresh. Thus, the salinization of well water and Regideso water is mostly due to the dissolution

of evaporates and the infiltration of runoff water due to anthropogenic pollution of urban origin, especially for

well water. Upon returning to the water table, the salt-laden irrigation water initially encountered the soil or the

unsaturated zone (Arques & Béraud, 2000; Bekkoussa et al., 2013).

The TDS values for the 10 sites range from 29.3 ppm to 348 ppm; the maximum value was recorded at site (9)

and the minimum value was recorded at site (2), which is further confirmed by the conductivity and salinity

values given above. Total dissolved solids (TDS) represent the total concentration of substances dissolved in

water. TDS consists of inorganic salts and some organic matter (Ghazali & Zaid, 2013). The most significant

et al., 2016).

Examining Tables 3 and 4 reveals the following key points:

It is a fact that well water contains significant amounts of copper compared to Regideso, which is spring water.

This is because Regideso undergoes treatment before use. Copper is often present in the resource, but it is

generally well removed by clarification, including coagulation. In cases of more significant pollution,

particularly in soft water, pre-demineralization (CO

2

+ soda or lime) is sufficient to precipitate copper

hydroxycarbonate. The high copper concentration in well water is undoubtedly due to a lack of certain

preliminary treatments. However, in Regideso water, these pre-treatments are carried out effectively, reducing

the heavy metal content (Legube, 2015). The maximum value recorded at site (4) is clearly explained by the

was facing rapid population growth. This rapid population growth, combined with the uncontrolled

establishment of dyeing workshops, garages, vehicle washing sites, illegal dumps, and wells turned into illegal

garbage dumps, had affected the quality of the shallow aquifer in the south of the Allada plateau (Dovonou et

al., 2022; Gove et al., 2001). In addition, chromium is present in small quantities in nature and is concentrated

mainly in basic rocks. Unlike siliceous rocks, chromium is a foreign element in water: its presence is linked to

discharges from electroplating workshops, which explains the high concentration at site (4) and in well water

(Kayalato et al., 2014). However, the average concentration of metal in wells and springs remains below the

relevant standard of 0.05 mg/L (WHO, 2017). This is a worrying situation, on the one hand because hexavalent

chromium is classified as carcinogenic to humans due to its toxicity, particularly when inhaled. On the other

hand, the displacement sites that also contain significant amounts of this metal are very recent. Some were

result is consistent with that found by Ngaram, who detected high nickel concentrations in the Chari River

(Ngaram, 2011). Nickel is an element that increases the risk of respiratory tract cancer through pulmonary

inhalation (Legube, 2015). The high concentration of this metal in well and Regideso water poses a permanent

that well water is adequately treated before use for drinking purposes, as the concentration of these metals is

even higher. Nickel is also found in groundwater, but only in small quantities. Its presence in water is clearly

linked to human activities, which explains the high concentration everywhere (Ahoussi et al., 2012; Arques &

Béraud, 2000). The public authorities must instruct the specialised service to analyse the water before it is used.

Dovonou et al., 2022).

This study took samples from two types of sites: closed wells and Regideso-captured sources used to develop

fountains.

We determined the physico-chemical parameters such as temperature, pH, conductivity, TDS, and salinity in

situ. We measured four trace metals in these samples: copper, chromium, nickel and silver.

The results are clear: all the physico-chemical parameters meet acceptable standards, with trace metal

concentrations remaining well within the norm (such as copper, silver, and chromium). F

and T

d

test revealed a

significant difference in conductivity, TDS, salinity, and in the concentration of silver, which was higher in well

We would like to thank the laboratory of the OCC (Office Congolais de Contrôle) in Bunia (DRC), and in

particular Mr. KHALID Abdallah, for supervising us in the laboratory during the completion of this work.

Author declares no conflict of interest.

1. Ahoussi, K. E., Koffi, Y. B., Loko, S., Kouassi, A. M., Soro, G., & Biemi, J. (2012). Caractérisation des

2. Arques, D., & Béraud, J.-F. (2000). Rooted maps on orientable surfaces, Riccati’s equation and continued