Mercury, a toxic trace metal, has been used extensively as an inexpensive and readily available method of extracting gold from fine-grained sediment. Worldwide, artisanal mining is responsible for one third of all mercury released into the environment. By testing bat hair from museum specimens and field collected samples from areas both impacted and unimpacted by artisanal gold mining in Perú, we show monomethylmercury (MMHg) has increased in the last 100 years. MMHg concentrations were also greatest in the highest bat trophic level (insectivores), and in areas experiencing extractive artisanal mining. Reproductive female bats had higher MMHg concentrations, and both juvenile and adult bats from mercury contaminated sites had more MMHg than those from uncontaminated sites. Bats have important ecological functions, providing vital ecosystem services such as pollination, seed dispersal, and insect control. Natural populations can act as environmental sentinels and offer the chance to expand our understanding of, and responses to, environmental and human health concerns.

Wildlife lead exposure is an increasing conservation threat that is being widely investigated. However, for some areas of the world (e.g., South America) and certain species, research on this subject is still scarce or only local information is available. We analyzed the extent and intensity of lead exposure for a widely distributed threatened species, the Andean Condor (Vultur gryphus). We conducted the study at two different scales: 1) sampling of birds received for rehabilitation or necropsy in Argentina, and 2) bibliographic review and extensive survey considering exposure event for the species' distribution in South America. Wild condors from Argentina (n = 76) presented high lead levels consistent with both recent and previous exposure (up to 104 μg/dL blood level, mean 15.47 ± 21.21 μg/dL and up to 148.20 ppm bone level, mean 23.08 ± 31.39 ppm). In contrast, captive bred individuals -not exposed to lead contamination- had much lower lead levels (mean blood level 5.63 ± 3.08 μg/dL, and mean bone level 2.76 ± 3.06 ppm). Condors were exposed to lead throughout their entire range in continental Argentina, which represents almost sixty percent (>4000 km) of their geographical distribution. We also present evidence of lead exposure events in Chile, Ecuador, and Peru. Lead poisoning is a widespread major conservation threat for the Andean Condor, and probably other sympatric carnivores from South America. The high number and wide range of Andean Condors with lead values complement the results for the California Condor and other scavengers in North America suggesting lead poisoning is a continental threat. Urgent actions are needed to reduce this poison in the wild.

The Air Quality Standards for Particulate Matter (PM) at high altitude urban areas in different countries, must consider the pressure and temperature due to the effect that these parameters have on the breath volume.This paper shows the importance to correct Air Quality Standards for PM considering pressure and temperature at different altitudes. Specific factors were suggested to convert the information concerning PM, from local to standard conditions, and adjust the Air Quality Standards for different high altitudes cities. The correction factors ranged from: 1.03 for Santiago de Chile to 1.47 for El Alto Bolivia. Other cities in this study include: Mexico City, México; La Paz, Bolivia; Bogota, Cali and Medellin, Colombia; Quito, Ecuador and Cuzco, Peru.If these corrections are not considered, the atmospheric concentrations will be underestimated.

Oil extraction activities in the Northern Peruvian Amazon have generated a long-standing socio-environmental conflict between oil companies, governmental authorities and indigenous communities, partly derived from the discharge of produced waters containing high amounts of heavy metals and hydrocarbons. To assess the impact of produced waters discharges we conducted a meta-analysis of 2951 river water and 652 produced water chemical analyses from governmental institutions and oil companies reports, collected in four Amazonian river basins (Marañon, Tigre, Corrientes and Pastaza) and their tributaries. Produced water discharges had much higher concentrations of chloride, barium, cadmium and lead than are typically found in fresh waters, resulting in the widespread contamination of the natural water courses. A significant number of water samples had levels of cadmium, barium, hexavalent chromium and lead that did not meet Peruvian and international water standards. Our study shows that spillage of produced water in Peruvian Amazon rivers placed at risk indigenous population and wildlife during several decades. Furthermore, the impact of such activities in the headwaters of the Amazon extended well beyond the boundaries of oil concessions and national borders, which should be taken into consideration when evaluating large scale anthropogenic impacts in the Amazon.

There is an ongoing debate on the fate of mercury (Hg) in areas affected by artisanal and small-scale gold mining (ASGM). Over the last 30 years, ASGM has released 69 tons of Hg into the southeastern Peruvian Amazon. To investigate the role of suspended matter and hydrological factors on the fate of ASGM-Hg, we analysed riverbank sediments and suspended matter along the partially ASGM-affected Malinowski-Tambopata river system and examined Hg accumulation in fish. In addition, local impacts of atmospheric Hg emissions on aquatic systems were assessed by analysing a sediment core from an oxbow lake. Hg concentrations in riverbank sediments are lower (20–53 ng g−1) than in suspended matter (∼400–4000 ng g−1) due to differences in particle size. Elevated Hg concentrations in suspended matter from ASGM-affected river sections (∼1400 vs. ∼30–120 ng L−1 in unaffected sections) are mainly driven by the increased amount of suspended matter rather than increased Hg concentrations in the suspended matter. The oxbow lake sediment record shows low Hg concentrations (64–86 ng g−1) without evidence of any ASGM-related increase in atmospheric Hg input. Hg flux variations are mostly an effect of variations in sediment accumulation rates. Moreover, only 5% of the analysed fish (only piscivores) exceed WHO recommendations for human consumption (500 ng g−1). Our findings show that ASGM-affected river sections in the Malinowski-Tambopata system do not exhibit increased Hg accumulation, indicating that the released Hg is either retained at the spill site or transported to areas farther away from the ASGM areas. We suspect that the fate of ASGM-Hg in such tropical rivers is mainly linked to transport associated with the suspended matter, especially during high water situations. We assume that our findings are typical for ASGM-affected areas in tropical regions and could explain why aquatic systems in such ASGM regions often show comparatively modest enrichment in Hg levels.

Dissolved organic matter (DOM) is recognized as a good indicator of water quality as its concentration is influenced by land use, rainwater, windborne material and anthropogenic activities. Recent technological advances make it possible to characterize fluorescent dissolved organic matter (FDOM), the fraction of DOM that fluoresces. Among these advances, portable fluorometers and benchtop fluorescence excitation and emission spectroscopy coupled with a parallel factor analysis (EEM-PARAFAC) have shown to be reliable. Despite their rising popularity, there is still a need to evaluate the extent to which these techniques can assess DOM dynamics at the watershed scale. We compare the performance of in-situ measurements of FDOM with laboratory measurements of fluorescence spectroscopy within the context of two distinct glacierized watersheds in Peru. Glacierized watersheds represent unique testing environments with contrasting DOM conditions, flowing from pristine, vegetation-free headwaters through locations with obvious anthropogenic influences. We used an in-situ fluorometer and a portable multimeter to take 38 measurements of FDOM, pH and turbidity throughout the two catchments. Additionally, samples were analyzed in the laboratory using the EEM-PARAFAC method. Results were compared to dissolved organic carbon (DOC) measurements using standard high-temperature catalytic oxidation. Our results show that the three techniques together were able to capture the DOM dynamics for both studied watersheds. Taken individually, all three methods allowed detection of the watershed DOM main points of sources but in a more limited way. Due to the narrow bandwidth of the portable fluorometer used in the study, FDOM measurements were almost non-detectable to protein-like substances. Indeed, the more demanding EEM-PARAFAC was able to both differentiate between potential sources of DOM and provide an estimate of relative concentrations of different organic components. Finally, similar to FDOM but to a lesser extent, the DOC measurements showed some limits where protein-like substances make up most of the DOM composition.

Marine litter, such as plastic bags, bottles, fabrics, or fishing gear, serve as a shelter for many marine organisms that are likely to colonize artificial substrata. Such assemblages can potentially turn marine litter into vectors of alien invasive species (AIS). Here, we report the abundance and diversity of macroinvertebrates inhabiting marine litter in Peruvian beaches. Results indicate that most of the fouled items found came from land-based sources (81.5%) and Bivalvia was the most abundant class (53.5%), mainly composed of the mussel Semimytilus algosus. No significant differences were found in the abundance and diversity of macroinvertebrates (class level) among sampling sites or sources of litter. Polypropylene and low-density polyethylene items were most frequently found with fouled biota. Although none of the identified species were non-native to the coast of Peru, we discuss marine litter as a potential source of AIS in this region.

In recent years, dense Alexandrium ostenfeldii blooms have been reported in different coastal areas. In this study, we report for the first time the occurrence of A. ostenfeldii blooms associated with the detection of paralytic shellfish toxins (PSTs) in the Peruvian scallop (Argopecten purpuratus) from Paracas Bay. Alexandrium ostenfeldii blooms occurred at the end of summer and early fall, after the increase of riverine input and under stratified conditions following a decrease in wind velocity. The highest abundances occurred during warm sea surface temperatures (18–27 °C). High PST concentrations that exceed the maximum permissible level (800 μg STX eq. kg⁻¹) occurred even under low A. ostenfeldii abundances (20 × 10³ cells l⁻¹). Our results contribute to a better understanding of the dynamics of A. ostenfeldii in coastal systems influenced by riverine inputs and upwelling and can be used to improve monitoring programs and allow the implementation of mitigation measures along the Peruvian coast.

Marine debris, in particular plastic debris and debris related to fishing activities, have an impact on marine mammals and seabirds. In marine-coastal species such as otariids, we can detect the incidence of these interactions through land-based observations. In this study, we recorded and described interactions between marine debris and the otariids Arctocephalus australis and Otaria byronia in a natural protected area in Peru, according to age class categories. Between 2016 and 2020, we recorded 151 animals that were directly impacted and/or were observed interacting with marine debris. Residual collars from fishing gear, ropes, plastic bags and unidentified material were recorded. Direct interactions with debris at colonies (e.g., plastic bags) were also recorded, as well as animals evidenced interacting with hooks. The age class category and species with the highest number of individuals impacted by residual collars were adult female A. australis and subadult male O. byronia. Single-use plastics were the most commonly bitten/moved waste by animals in the reserve. In the case of hooks, these were mostly lodged in the mouths of otariids. Our results highlight the importance of continuing to promote segregation at source, as well as the correct disposal of waste, locally and globally, to mitigate impacts on marine fauna.

Marine litter can be found along coasts, continental shelves and slopes, down into the abyss. The absence of light, low temperatures and low energy regimes characterising the deeper habitats ensure the persistence of litter over time. Therefore, manmade items within the deep sea will likely accumulate to increasing quantities. Here we report the litter abundance encountered at the Pacific abyssal nodule fields from the Peru Basin at 4150 m depth. An average density of 2.67 litter items/ha was observed. Litter composed of plastic was the most abundant followed by metal and glass. At least 58 % of the items observed could be linked to the research expeditions conducted in the area and appeared to be mostly accidental disposals from ships. The data gathered was used to address temporal trends in litter abundance as well as the impact of human on-site presence and return cruises in the context of future deep-sea mining efforts.