Assessment of a wide array of contaminants of emerging concern in a Mediterranean water basin (Guadalhorce river, Spain): Motivations for an improvement of water management and pollutants surveillance

This study investigates the occurrence and distribution of 185 organic contaminants (regulated pollutants and contaminants of emerging concern; CECs) in surface and groundwater of the Guadalhorce River basin (southern Spain) providing the most detailed dataset regarding organic pollution presented so far in this area. Up to 63 contaminants were detected in a monitoring campaign conducted in March 2016. Most contaminants were detected more frequently in surface water where they generally present higher concentrations suggesting the prevalence of wastewater discharges into streams as the main pollutant sources. In general, hydrophobic CECs presented the highest frequencies of detection and concentrations, which can be a consequence of several factors: (1) hydrophobic compounds show a higher retardation factor, which result, along with a continuous contaminant input, in a widespread and homogeneous distribution. In contrast, hydrophilic contaminants are more easily transported by water flows towards the lower basin and potentially accumulate as driven by groundwater flow and because of low renewal rates in the detrital aquifers caused by re-pumping and irrigation return flows in agricultural lands; (2) hydrophobic CECs studied in this research are mainly personal care products and organophosphate esters flame retardants and plasticizers, which are present in many different products and are used in large amounts; Also, (3) use of biosolids (reclaimed sewer sludge) as fertilizer for crops is potentially an additional diffuse source of organic pollutants in the study area contributing to a widespread distribution, especially for hydrophobic compounds. Obtained results highlight the need to better define the potential risk of non-regulated contaminants in water resources as well as the great impact of untreated wastewater discharges

New hydrochemical and isotopic data in the karstic spring of Maro (Nerja, Málaga). Considerations on the origin of solutes and on the influence of the vadose zone ventilation

The previously stated model concerning the behaviour of the karstic spring of Maro is corroborated with new data from the 2004-2014 period. Sulphate isotopes allow linking the origin of solutes with the dissolution of Mesozoic gypsum. Other hydrochemical data (pH, DO) suggest the association of the spring with relatively large and well-ventilated karstic conduits in the vadose zone of the carbonate aquifer drained by the spring. During the winter season, such conduits could be affected by pressure or temperaturedriven high-PCO2 airflows that may be responsible for local decreases in the pH of the spring waterEl modelo de funcionamiento del manantial kárstico de Maro propuesto en estudios previos se corrobora con nuevos datos del periodo 2004-2014. Los isótopos del sulfato precisan el origen de solutos por disolución de yesos mesozoicos. Otros datos hidroquímicos (pH, OD) sugieren la asociación del manantial con conductos kársticos relativamente grandes y bien ventilados dentro de la zona vadosa del acuífero carbonático triásico al que drena. En el periodo invernal, por diferencias de presión o temperatura entre el interior y el exterior de estos conductos, se pueden producir flujos de aire con PCO2 relativamente elevada hacia los mismos, con el resultado de inducir disminuciones locales del pH del agua del manantia

Platinum-Group-Elements and Total Organic Carbon in hyperalkaline springs at the Ronda peridotites (Malaga, Spain) as proxies of the origin of dissolved methane gas.

The serpentinization of ultramafic rocks is a process in which minerals of ferromagnesian nature (e.g., olivine) are transformed into serpentine and produce groundwater with a very high pH. In these settings, CH4 can be produced by combining H2 from serpentinization and CO2 from the atmosphere, soil, carbon-bearing rocks, or mantle, although the microbial generation of CH4, mediated by methanogens utilizing CO2, formate and/or acetate can be another source in these aquifers. In this sense, the hydrochemistry of hyperalkaline springs can provide valuable information about gas origin. The Ronda peridotites (Malaga province, Spain) are one of the world’s largest outcrops of the subcontinental mantle (~450 km2). Hyperalkaline springs (pH>10) emerging along faults present a permanent low outflow (<1 L/s), Ca2+- OH- facies and residence times exceeding 2,000 years. The fluids, poor in Mg2+ and rich in K+, Na+, Ca2+ and Cl-, also contain significant concentrations of dissolved CH4 and other hydrocarbons. Water samples have been collected from eight hyperalkaline springs and analyzed for major, minor and trace elements, including Platinum Group Elements (PGE) and Total Organic Carbon (TOC). The most mobile PGEs (Pd and Rh) are present in all the springs, indicating the existence of potential catalysts for the abiotic synthesis of CH4. High TOC concentrations are observed in some studied springs where previous analyses (i.e., bulk CH4 isotopes) have indicated a microbial CH4 origin.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Screening and Distribution of Contaminants of Emerging Concern and Regulated Organic Pollutants in the Heavily Modified Guadalhorce River Basin, Southern Spain

Emerging pollutants have aroused an increasing concern due to their ubiquitous presence in the environment and harmful potential. Both emerging (e.g., pharmaceuticals and personal care products) and regulated organic pollutants pose a serious threat to water quality and their presence and spatial distribution are complicated to address as they can derive from several factors: distribution of point and diffuse sources, environmental conditions, hydrogeological features of the region and inherent properties of the considered contaminants. In this study, a ground and surface water monitoring campaign was conducted in the three main detritic groundwater bodies of an extensive and heavily modified river basin in order to draft an initial description of the occurrence and distribution of a wide range of organic contaminants. In total, 63 out of 185 target pollutants were detected. An attempt to understand the importance of different factors governing the distribution of some of the most frequently found pollutants was made. Antibiotics spatial distribution is potentially influenced by the hydrogeological functioning of the basin modified by hydraulic infrastructures (reflected by hydrochemistry and environmental tracers delta H-2 and delta O-18), not directly related to the distribution of potential sources. The presence of other organic pollutants does not reflect an evident correlation with flow pathways. Differences in contaminant occurrence are potentially attributed to the way pollutants are released into the environment as well as physico-chemical properties

Coronavirus pandemic: an opportunity to study the anthropogenic impact on micro-climate conditions and CaCO3 crystal morphology in the Nerja Cave (SE Spain)

Following the declaration of the COVID-19 pandemic, the Spanish Government restricted non-essential movements of all citizens and closed all public spaces, such as the Nerja Cave, until May 31, 2020. This particular condition of the closure of the cave provided a unique opportunity to study the micro-climate conditions and carbonate precipitation in this tourist cave without the presence of visitors. Our results show the significant effect of visitors on the air isotopic signature of the cave and on the genesis of the extensive dissolution features affecting the carbonate crystals formed in the tourist sector of the cave, alerting us to the possible corrosion of the speleothems located there. The movement of visitors within the cave also favours the mobilisation of aerial fungi and bacterial spores and their subsequent sedimentation simultaneously with the abiotic precipitation of carbonates from the drip water. The traces of these biotic elements could be the origin of the micro-perforations previously described in the carbonate crystals formed in the tourist galleries of the cave, but they are subsequently enlarged due to abiotic dissolution of the carbonates through these weaker zones.It is financed by the Nerja Cave Foundation, co-ordinated by its Research Institute and authorized by the Consejería de Cultura (Junta de Andalucía). This study is also a contribution to the Research Groups RNM-308 and RNM-126 of the Junta de Andalucía and to the Projects PID2021-125619OB-C21, PID2021-125619OB-C22, TED2021-130549B-I00 funded by MCIN/AEI/10.13039/ 501100011033. Funding for open access charge: Universidad de Málaga / CBUA

Condensation water in heritage touristic caves: Isotopic and hydrochemical data and a new approach for its quantification through image analysis

Condensation water is a major factor in the conservation of heritage caves. It can cause dissolution of the rock substrate (and the pigments of rock art drawn on it) or covering thereof with mineral components, depending on the chemical saturation degree of the condensation water. In show caves, visitors act as a source of CO2 and thus modify the microclimate, favouring negative processes that affect the conservation of the caves. In spite of their interest, studies of the chemical composition of this type of water are scarce and not very detailed. In this work we present research on the condensation water in the Nerja Cave, one of the main heritage and tourist caves in Europe. The joint analysis of isotopic, hydrochemical, mineralogical and microbiological data and the use of image analysis have allowed us to advance in the knowledge of this risk factor for the conservation of heritage caves, and to demonstrate the usefulness of image analysis to quantify the scope of the possible corrosion condensation process that the condensation water could be producing on the bedrock, speleothem and rock art. To our knowledge, this application of image analysis (relative to the condensation water in caves) is the first one of this type that has been documentedNerja Cave Foundation Funding for open access charge: Universidad de Málaga / CBU

Study of the presence and environmental risk of organic contaminants policed by the European Union and other organic compounds in the water resources of a region overlapping protected areas: The Guadiaro River basin (southern Spain)

The study presented here is a first qualitative assessment of the occurrence of organic contaminants contemplated and not yet contemplated in European Union environmental legislation in water resources in the little anthropized Guadiaro River basin (70% of its area is covered by natural vegetation), in southern Spain. Water samples were collected from four carbonate aquifers, two detrital aquifers and four surface water courses and were analyzed for (i) 171 organic contaminants, (ii) major ions and (iii) stable isotopes (δ18OH2O, δ2HH2O, δ13CDIC). An environmental risk assessment was conducted through calculation of risk quotients comparing measured concentrations with ecotoxicological data found in the literature. Twenty-five organic contaminants were detected, at least once, including pesticides, pharmaceuticals, drugs of abuse and polycyclic aromatic hydrocarbons (PAHs). Cocaine and its main metabolite were detected in 85% and 95% of water samples, respectively (0.001–0.18 μg/L and 0.004–0.6 μg/L, respectively). Pyrene (PAH) was found in all water samples (0.001–0.015 μg/L) and forest fires were pointed out as a potential diffuse source. Relationship between rivers and aquifers is reflected by the distribution of organic contaminants, essentially the drugs of abuse. Concentration of contaminants were generally higher in groundwater samples, especially from detrital aquifers, potentially due to an accumulation process promoted by irrigation-return flows and by its slow dynamic compared to that of karstic systems. Pyrene concentration was also higher in some springs from karstic aquifers. Hence, calculated risk quotients were in general higher in groundwater, meaning that the threat to surface aquatic systems can grow as aquifers increase their influence on the water courses as the dry season progresses. The relationship between δ13CDIC and most organic contaminants (especially pyrene) reveal the role of the soil as storage media.Funding for open access charge: Universidad de Málaga / CBU

Discriminating organic carbon from endokarstic moonmilk-type deposits by LIBS. The case of a natural carbonated Martian analogue

Moonmilk-type deposits exemplify carbonated Martian analogues existing in the subsurface of Earth, an endokarstic speleothem with a possible biochemical origin composed principally by carbonates, mainly huntite and dolomite. In this work, samples of moonmilk located in Nerja Cave (southern Spain) have been studied by LIBS with the aim of identifying carbon of biogenic origin by establishing a relationship between a molecular emission indicator, CN signal, and the organic carbon content. The characterization of this kind of carbonate deposit with a multiple mineralogical composition has been completed using scanning electron microscopy (SEM), energy dispersive X-ray (EDX) and X-ray diffraction techniques for qualitative and semi-quantitative analysis. The information attained from LIBS regarding energy thresholds and time-resolved kinetics of CN emissions provides useful insight into the identification of different molecular emitters, namely organic and inorganic CN, depending on the laser irradiance and time settings conditions. These promising results are of application in the search and identification of biosignatures in upcoming planetary missions with astrobiological purposes.Funding for open Access charge: Universidad de Málaga / CBUA. This work was supported by Project PID2020-119185 GB-I00 from Ministerio de Ciencia e Innovación, Spain. L. García-Gómez grateful to the Spanish Ministerio de Economía y Competitividad for the concession of an FPI grant

Hydrogeological, hydrodynamic and anthropogenic factors affecting the spread of pharmaceuticals and pesticides in water resources of the Granada plain (Spain)

The anthropogenic organic contaminants contemplated in the environmental legislation, as well as those of emerging concern, threaten the quality of water resources to a degree that remains largely unknown. Contaminant exposure in the aquatic environment is a crucial element if a full understanding of the risk is pursued. There are still many uncertainties about the occurrence of organic pollutants and behavior in the hydro(geo)logical media in large scale areas. The case study of the unconfined aquifer of the Granada Plain (approximately 200 km2) is presented here. Two surface and groundwater monitoring campaigns were conducted (March 2017 and June 2018). In total, 41 out of 171 target organic pollutants were detected, at least once: 17 pharmaceuticals or drugs of abuse, 21 pesticides or their metabolites and three polyaromatic hydrocarbons. In addition, physico-chemical parameters were measured during the monitoring campaigns and hydrochemical parameters and stable isotopes (δ2H, δ18O, δ13C) were analyzed. Statistical tests confirmed the significance of seasonal changes for some of these parameters (e.g., EC, Cl-, F-, δ18O, δ13C), revealing the influence from snowmelt water input on streams and the intensification of irrigation. In March 2017, the group of pesticides (largely represented by triazines) predominated, whereas the frequency of detection of pharmaceuticals increased substantially in June 2018. Results suggest four main factors affecting the spatial and seasonal variation of organic pollutants in the aquifer: the anthropogenic factor determining the period of contaminant release throughout the year (pesticide application period and growth of tourism) along with irrigation practices that include reclaimed wastewater; unsaturated zone thickness; [...]This article is a contribution to the Research Groups RNM-308 and RNM 128 of the “Junta de Andalucía” and the project “Study, detection and behavior of emerging contaminants in anthropized watersheds in Andalusia-EMAN (P20_397)”. We are grateful to technical translation specialists GeoTranslations for proofreading the English version. We would also like to thank the Associate Editor, and the anonymous reviewers, who largely contributed to the improvement of the manuscript. Funding for open access charge: Universidad de Málaga / CBU

Experimental survey of soil CO2 content over a karstic cave in mediterranean climate

The CO2 content and the temperature of the air have been measured within the scarce soil (although with relatively high organic matter concentration) which partially covers the carbonate outcrops over the Nerja Cave (Málaga). General yearly average values of around 850 ppm and 25 ºC have been identified, both using continuous recording devices and separated measures with portable equipment. Temperature evolution closely follows that of the outside atmosphere. Spatial variations in CO2 contents are related with the vegetal cover and with the soil depth. Seasonal variations are important, with a maximum of more than 1000 ppm in May (main vegetation development) and minimum (around 350- 500) in December. Daily oscillations have also been identified, ranging up to more than 600 ppm in the period of maximum CO2 production. These results agree with estimates based in hydrogeochemical modelling as well as in the TOC content of drip water to the cav