*4.2.4 Hg in air*

*Applied Geochemistry with Case Studies on Geological Formations, Exploration Techniques…*

**Study mine MC BR SQ SC LM Sampling LK (5) WT BO WT (6) AMD (3) WT WC** As >2000 79 2.6 >1.5 2.3 >2000 b.d. Cd 14–54 483 3.8 0.1–26.6 >3200 6470 1.5 Cu >2000 >2000 12.3 1–12.6 >8300 >2000 52 Fe2O3 total >100,000 >100,000 90 30–100 >189,000 >100,000 100 Ni 30–143 559 80.1 1.8–22.3 >3500 5620 120 Pb 0–67 199 8.5 0.4–21.6 >2800 0.5 1 Sb 0–1 b.d. 6.1 0.1–3.0 1.3 11.8 1.4 Sn b.d. b.d. b.d. b.d. b.d. 3 2 Zn >2500 >2500 93.6 57–2520 >550,000 >2500 365 pH 2–2.6 2.4 5.7 6.2–7.1 2.5–4.3 1.8 8.3 *Values in μg/L. b.d.: below detection. Mina Concepción (MC), Brunita (BR), San Quintín (SQ ), San Cristóbal (SC), and Las Moreras (LM). LK: leakage; WT: water table; BO: borehole; AMD: acid mine drainage; and WC:* 

**Alcudia Valley Mazarrón**

**Cartagena-La Unión**

upper tailing unit of Las Moreras shows much lower pH values (2.8–5.6), due to the

The composition of leakage sample waters of a restored mine pond (Mina Concepción) indicates that these waters represent acid mine drainage, as reflected by their very low pH (<2.6) (**Table 5**). Trace element contents are very high for Cu and Zn (>2 mg/l), both higher than the EPA's maximum recommended limits for irrigation waters (0.2 mg/l for Cu and 2 mg/l for Zn [23]). This is also the case for As in samples leaking from the dyke wall and the puddle. Lead also goes beyond the legislation limits in samples from the dyke wall and the drainage pipes. Acid mine drainage was observed in the northern part of the Brunita mine pond (pH < 2.4) (**Table 5**). The concentrations were very high for Cu, Zn, Cd, Ni, and Fe in the water sample. Results from complementary techniques (ERT), shown in Section 4.3 of this chapter, have confirmed the formation of AMD waters in Mina Concepción and Brunita mines. One water sample was collected at 8 m depth in the borehole from San Quintín mine (**Table 5**). The high EC and acidic pH values are consistent with water from ore deposits retained in tailing ponds. Three samples showing low pH and significantly high trace element contents indicate AMD flowing from the remaining tailings. AMD was not observed in samples from the watercourse crossing the mining zone (**Table 5**). pH values in these waters are circumneutral, and EC values and metal contents are significantly lower than in samples from the tailings. Samples collected up- and downstream display the lowest trace element contents. Higher metal contents have been measured in the rest of watercourse samples, denoting

that trace element contamination occurs through the mining area.

With regard to the San Cristóbal mine pond, AMD was clearly detected in the water sample: pH < 2, high redox potential, high EC, and Total dissolved salt values. Concentrations of trace elements were very high for As and Cu (>2000 μg/L), Zn

sulfide content and the complete absence of calcite.

*Fe2O3 total, trace element content, and pH values in the water samples.*

**98**

*4.2.3 Waters*

*watercourse.*

**Table 5.**

**Mine district** **Iberian pyrite belt**

> A singular case occurs in San Quintín mine where significantly high Hg content has been identified in the mine area. Gaseous Hg emissions were measured from the tailings and surrounding soils (**Figure 3**). The total gaseous mercury distribution in the studied area significantly changes between summer and winter. The area affected by TGM values up to 100 ng m<sup>−</sup><sup>3</sup> is restricted to the surroundings of the cinnabar stockpile in winter, but the affected area is 0.16 km2 , and extends into the Don Quixote Route in summer. TGM values are lower than the limit recommended for the general population by the World Health Organization (WHO) (1000 ng m<sup>−</sup><sup>3</sup> ) for the worst scenario [24]: higher temperature and solar radiation during summer.
