Accumulation Assessment of Mo4+, Pb++, and Cu++ in the Acidic Water of Copper Mines with Lemna minor and Lemna gibba

The principal anion and cation results of acidic mine water’s physicochemical characteristics are displayed in Table 1. The temperature varied from 18.6 to 24.8 °C (mean: 22.6 ± 1.2 °C). The pH of the water altered from 5.84 to 5.62 (mean: 5.76 ± 0.14), and the EC values were between 2.64 and 2.38 mS cm⁻¹ (mean: 2.55 ± 0.08 mS cm⁻¹, referenced from Sasmaz Kislioglu [51]). Throughout the eight-day experiment, daily field samples of water were collected. Table 1 displays the average concentrations of Mo, Pb, and Cu in the acidic mine water, which were 30 ± 4, 260 ± 12, and 15,535 ± 322 μg L⁻¹, respectively (p

The mean values of Mo, Cu, and Pb in the acidic mine fluids exceeded the U.S. EPA’s [27] and Agency for Toxic Substances and Disease Registry (ATSDR)’s [44] limit levels, as shown in Table 1. The research area’s acidic mine water included varying quantities of Mo (28.4 to 31.6 μg L⁻¹). Most natural waters have Mo concentrations of around 10 μg/L or less [26]. The research area’s average Mo value was higher than the WHO-established threshold levels (10 mg L⁻¹) for drinking water [23] (Table 1). According to the U.S. EPA [25], the average Pb levels in these natural waters have been recorded as 10–15 µg/L [28]. Water leaks from the mine contaminate the environment’s soil and water, and cleaning these contaminated soils and waterways is difficult [55,56]. According to Ning et al. [57], the average WHO readings [28] for heavy metal levels were not as high as those found in the water surrounding Pb resources. A median Mo content of 0.5 mg/L was reported by Reimann and de Caritat [58] for stream waters worldwide. The estimates for world rivers are between 0.11 and 8.63 (mean 1.21 mg/L) [50] and around 0.42 mg/L [59,60]. Rivers in India contain up to 20 mg/L [61] and 8.6 mg/L [62].

Based on the main cations and anions (Ca–Mg–HCO₃; Ca–Mg–Fe–SO₄; Na–F–NO₃), the waters in the research region were divided into three groups. The water types in the aquifer were identified using Piper’s [63] triangular drawing approach. Over 90% of the cations in the aquifer were found in the examined fluids, with Ca, Mg, Fe, Na, S, K, and Mn being the most common. In the research area waters, bicarbonate and sulfate were the main anion species, constituting 85–90% of all the anions. Ca–Mg–Fe–Na–SO₄ HCO₃ water is one possible classification for Maden Cu mine acidic water.

Cleaning and restoring contaminated areas can be done affordably, effectively, sustainably, and economically with phytoremediation. Before building a decontamination system, knowledge regarding heavy metal effects on plant physiology should be acquired to optimize the system [64]. The uptake process of Mo, Pb, and Cu can be impacted by variables such as the metal’s bioavailability, the contaminant’s chemical characteristics, organic matter contents, plant species, phosphorus, pH, and contaminant-specific environmental factors [65]. Numerous aquatic plants have been successfully employed to monitor contaminated settings and are recognized as heavy metal pollution indicators [66]. Heavy metals such as Mo, Ag, Pb, Au, Cu, As, Co, Hg, Zn, Tl, and Cd are considered hazardous and poisonous for their ability to accumulate in biological systems.

Prior to commencing the investigation, we found that the L. minor (LM-0) and L. gibba (LG-0) had Mo levels of 2.16 and 0.29 mg kg⁻¹, respectively, (p Figure 4). These values were considered the control group values of these plants. On the first day, 2.89 and 0.97 mg kg⁻¹ (p L. minor and L. gibba. During the first five to six days of the experiment, both plants’ absorption of Mo from the acidic mining water marginally increased. On the fifth and sixth days, the L. gibba and L. minor removed 84 and 77 times more Mo than the control from the acidic mine water. L. gibba showed outstanding Mo accumulation ability between days 5 and 7. L. minor accumulated rapidly after the fifth day until the end of the experiment. On the eighth day, it accumulated 169 ppm Mo, which corresponds to approximately 77 times more Mo accumulation than the control sample. To determine how much water the Lemna minor plant cleaned on the eighth day, the control concentration (2.16 mg kg⁻¹) was subtracted from the eighth-day Lemna minor concentration (169 mg kg⁻¹). Then, the resulting value was divided by the Mo value (30 μg L⁻¹) in one liter of water (=169.000–2.160/30) to determine how much water (5561 L) the plant cleaned of Mo. The L. gibba had removed molybdenum from 274 L of acidic mineral water by the end of the sixth day of the study.

The L. minor and L. gibba showed limited, comparable increases in Pb accumulation throughout the first five days of the experiment. Both plants showed extremely high accumulation ability, which increased linearly from the fifth to the eighth day. The L. gibba accumulated 30 (78.2 mg kg⁻¹) and 109 times more Pb (189 mg kg⁻¹) from the acidic water on days 5 and 8, respectively, compared to the control samples of each plant (Figure 5).

The L. gibba regularly showed significant increases in copper accumulation throughout the experiment, accumulating 9866 ppm (p L. minor showed substantial accumulation ability during the first four days of the experiment. By the end of the fourth day, it had accumulated 12,668 ppm of copper. This value indicates 1150 times more accumulation than the control samples. Between the fifth and eighth days, the L. minor accumulation levels decreased because the plant was sufficiently saturated with copper (Figure 6).

Plants such as L. minor and L. gibba were used by Sasmaz et al. [33] to determine metal accumulation rates and optimal harvesting times in gallery water from the Keban Pb–Zn mine. The pH of gallery water is 7.36 and has a neutral composition. Both plants achieved higher accumulations in acidic waters than in the neutral mineral waters of the Keban Pb–Zn mine. They determined optimal harvesting times by monitoring daily changes in the metallic concentrations of both plants. Based on the acquired data, the L. gibba and L. minor accumulated Pb and Cu at 2888 and 3708 times and 108 and 147 times greater than those found in gallery water, respectively.

In the same experiment, Sasmaz Kislioglu [51] examined the Ag, Au, and As accumulations of L. minor and L. gibba in acidic mineral water. Compared to the control samples of these plants, the L. minor and L. gibba showed effective and high accumulation abilities for As, Au, and Ag in the acidic water of Cu mining areas. For instance, 30 and 907 times for As, 336 and 394 times for Au, and 240 and 174 times for Ag, respectively.

For eight days, Sasmaz and Obek [67] gathered evidence of L. gibba’s ability to extract As, U, and B from secondarily treated urban wastewater. During the first two days of the study, L. gibba showed the highest uptake ratios for B, U, and As with removal rates of 40%, 122%, and 133%, respectively. These results imply that L. gibba may serve as a natural strategy for reducing the amount of these pollutants in wastewater. L. minor has a higher capacity for collecting lower amounts of Cr and Ni, according to Goswami and Majumder [29]. Furthermore, Au and Ag uptake from secondarily treated municipal wastewater by L. gibba was examined by Sasmaz and Obek [38]. In the first six days of their investigation, both Au and Ag accumulated rapidly. However, the Ag and Au accumulations fluctuated after day 6, perhaps because the plant had reached saturation. The greatest accumulations of Au and Ag on the fifth and sixth days of the study were 2303% and 247%, respectively. Uysal [68] investigated Lemna’s capacity to sorb Cr at various pH and concentration levels and found that it could still absorb Cr from water despite undergoing harmful consequences. During the 12-day experiment, Abdallah [69] noted that L. gibba performed well, accumulating over 84% of the Cr in the solution. L. minor is a viable choice for repairing habitats damaged with Pb and Cr because it can absorb these metals quickly and efficiently, according to Ucuncu et al. [70]. According to Goswami et al. [30], L. minor adequately corrected low-concentration As-contaminated waters. L. gibba and L. minor’s effectiveness in extracting Y, La, and Ce from contaminated gallery water was ascertained by Sasmaz et al. [71]. L. gibba accumulated more metals than L. minor when compared to the control samples. Salvinia natans and L. minor are two aquatic macrophytes whose biological reactions and phytoremediation potential were examined by Leblebici et al. [72]. They discovered that L. minor was superior to S. natans as a Cd accumulator, while S. natans was a more effective Ni and Pb accumulator. According to Amare et al. [73], L. minor should be a moderate phytoaccumulator of Cd, Cu, Ni, and Cr and a high phytoaccumulator of Mn, Co, Zn, and Fe. According to Tatar et al. [74], L. minor has a high removal capacity for Ag, Hg, Mn, Pb, Zn, Fe, Ba, Sb, Co, and P, while L. gibba has a good uptake capacity for Mo, Cu, Ca, Na, Mg, Se, and S.