Acute Ecotoxicity Potential of Untreated Tannery Wastewater Release in Arequipa, Southern Peru

Abstract

The centralized Rio Seco Industrial Park (RSIP) tannery collective in the Southern Peruvian city of Arequipa releases untreated tannery wastewater into a proximal creek that is a tributary of the Chili River. As industrial leather tanning wastewater contains high concentrations of metal(loid)s, salts, dyes, and organics, this complex mixture could exert a myriad of toxicological effects on the surrounding ecosystem. The RSIP effluent was analyzed to quantify the acute ecotoxicity and ecotoxicological status of this untreated industrial wastewater at multiple trophic levels with the following bioindicators: the floating macrophyte Lemna minor, invertebrates Daphnia magna and Physa venustula, and the amphibian Xenopus laevis. A physicochemical characterization of the RSIP effluent revealed a highly contaminated waste stream. In addition to chromium (10.4 ± 0.4 mg/L) and other toxic metals, the water harbored extremely high concentrations of total dissolved solids (67,770 ± 15,600 mg/L), biochemical oxygen demand (1530 ± 290 mg/L) and total nitrogen (490 ± 10 mg/L). The toxicological responses of certain bioindicator species tested were evaluated after exposure to 0, 1.5, 3.0, and 4.5% untreated tannery wastewater blended with dechlorinated tap water. L. minor experienced a significant decrease in the number of fronds, wet weight, and dry weight at the lowest blended wastewater of 1.5%. Bioassays with D. magna showed the effect on neonatal mortality with a calculated LC50 of 1.1% for 48 h. Bioassays with P. venustula embryos showed high sensitivity to diluted effluent with complete mortality at 3.0% wastewater and above. Finally, X. laevis showed a high sensitivity to the dilutions with an LC50 of 1.6 for embryos and 1.8% for tadpoles. Although RSIP wastewater contains many potentially toxic components, chromium and total dissolved solids, with a major contribution from sodium, are best correlated with acute toxicity variables. This suggests that conductivity or analogous measurements could provide a rapid and affordable forensic tool to query acute ecosystem pressures. Collectively, the results indicate that the release of untreated tannery wastewater from RSIP can exert pronounced acute impacts across trophic levels with the need for treatment or dilution to below 1% of total flow. As the assays addressed acute toxicity, the necessary treatment and/or dilution to mitigate chronic effects is likely much lower. In conclusion, untreated RSIP tannery wastewaters represent an ecological risk to downstream aquatic ecosystems; this needs to be addressed to prevent current and future environmental consequences.

Ecotoxicological Properties of Pure and Phosphorus-Containing Graphene Oxide Bidimensional Sheets in Daphnia magna

“…This suggests that GOP is much more toxic than GO when exposed to the environmental biomarker D. magna at 24 h acute toxicity. Thus, environmental biomarkers are important for evaluating the materials’ toxicities, allowing for the determination of lethal concentrations for aqueous applications [ 46 ].…”

“…This suggests that GOP is much more toxic than GO when exposed to the environmental biomarker D. magna at 24 h acute toxicity. Thus, environmental biomarkers are important for evaluating the materials' toxicities, allowing for the determination of lethal concentrations for aqueous applications [46]. It was also seen that the Probit curve has a different trend behavior; while, for GO, the extreme values are relatively close to its LC 50 value, for GOP, this does not occur since the extreme values could not be calculated accurately.…”

Heavy Metal Bioaccumulation in Peruvian Food and Medicinal Products

“…Taking into account the above, there is no clear correlation between high- or low-reported cases and location, at least from the perspective of administrative boundaries, so further studies should focus on the specific characteristics of local rivers used by downstream agricultural activities. For example, Tejada-Meza et al [ 109 ] recently documented high tannery-derived metal contents in surface waters draining directly into the Chili River (Arequipa Region), whose waters are used to irrigate thousands of hectares of agricultural crops. Additionally, mining and other human activities could affect metal concentrations in river waters used to irrigate agricultural fields in this arid region of Peru (e.g., [ 110 ]), not mentioning that rivers in this part of the Andes naturally contain metals (e.g., [ 111 ]); for example, Regis et al [ 112 ] reported high As concentrations in the Tambo river (Arequipa Region), and such metal has been reported in many food/medicinal products in that same region ( Table S4 ).…”

Urban Stormwater Quality in Arequipa, Southern Peru: An Initial Assessment

“…Furthermore, Mo, Na, and P (not regulated in Peru) could be a potential problem; even though they are considered nutrients for crop plants, excessive amounts of those metals can significantly damage downstream aquatic ecosystems (e.g., [51,52]), so further investigations should focus on potential environmental effects of urban stormwater discharges on downstream native species such as fish, as excessive Na concentration have been linked to sub-lethal effects in rivers [53]. For example, following the methods recently used by Tejada-Meza et al [54], pollutant concentrations in the Chili River upstream and downstream from Arequipa can be tested for several bioindicators, to see if significant changes can be detected. Similarly, a simple ecological assessment in both portions of the river can also easily determine if discharges from the city are affecting native life.…”

“…Considering this and for the specific case of southern Peru where climate is extremely dry and summers are wet, urban stormwater in Arequipa has the potential to be a serious environmental threat, provided that those waters are soon used to produce food and not mentioning the possible ecological consequences to downstream ecosystems. Recently, Tejada-Meza et al [54] revealed the deadly effects of untreated metal-rich industrial effluents in four bioindicators in Arequipa, providing solid evidence that environmental regulations in the region need to be strengthened. Moreover, new regulations must include urban stormwater quality, as evidenced in this investigation.…”