Phylogenetic Structure and Metabolic Properties of Microbial Communities in Arsenic-Rich Waters of Geothermal Origin

Arsenic behavior in soil-plant system under the manure application with the combination of antibiotic and roxarsone

Limited attention has been given to the interaction between antibiotics and arsenic in the soil-plant system. In this investigation, Medicago sativa seedlings were grown in soil treated with cow manure containing oxytetracycline (OTC) or sulfadiazine (SD), as well as arsenic (introduced through roxarsone, referred to as ROX treatment). The study revealed a notable increase in As(III) and dimethylarsinic acid (DMA(V)) levels in rhizosphere soils and plant root tissues as arsenic contamination intensified in the presence of antibiotics, while concentrations of As(V) and monomethylarsonic acid (MMA(V)) decreased. Conversely, elevated antibiotic presence resulted in higher levels of As(V) but reduced DMA concentrations in both rhizosphere soils and plant root tissues in the presence of arsenic. The arsenic biotransformation gene aioA was inhibited by arsenic contamination when antibiotics were present, and suppressed by antibiotic contamination in the presence of arsenic, especially in SD treatments, resulting in reduced expression levels at higher SD concentrations. Conversely, the arsM gene exhibited consistent upregulation under all conditions. However, its expression was found to increase with higher concentrations of ROX in the presence of antibiotics, decrease with increasing SD concentrations, and initially rise before declining with higher levels of OTC in the presence of arsenic. Bacterial genera within the Proteobacteria phylum, such as Geobacter, Lusitaniella, Mesorhizobium, and Methylovirgula, showed significant co-occurrence with both aioA and arsM genes. Correlation analysis demonstrated associations between the four arsenic species and the two arsenic biotransformation genes, emphasizing pH as a critical factor influencing the transformation and uptake of different arsenic species in the soil-plant system. The combined stress of antibiotics and arsenic has the potential to modify arsenic behavior and associated risks in soil-plant systems, highlighting the necessity of considering this interaction in future research endeavors.

Effects of simulated acid rain on hydrochemical factors and microbial community structure in red soil aquifers

Acid rain can lower the pH of groundwater and affect its hydrogeochemistry and microbial ecology. However, the effects of acid rain on the hydrogeochemistry and microbial ecology of red soil groundwater systems in southern China are poorly understood. Previous research had mainly investigated the sources and patterns of groundwater acidification, but not the microbial mechanisms that contribute to this process and their associations with hydrochemical factors. To address this knowledge gap, we conducted a soil column experiment to simulate the infiltration of acid rain through various filter materials (coarse, medium, and fine sand) and to examine the hydrochemical and microbial features of the infiltrate, which can reveal how simulated acid rain (pH 3.5-7.0) alters the hydrochemistry and microbial community composition in red soil aquifers. The results showed that the pH of the leachate decreased due to simulated acid rain, and that the leaching efficiency of nitrogen and metal ions was influenced by the particle size of the filter media. Illumina 16S rRNA gene sequencing revealed that the leachate was dominated by Proteobacteria, Patescibacteria, Actinobacteria, and Acidobacteria, with Proteobacteria accounting for 67.04-74.69% of the bacterial community and containing a high proportion of nitrifying and denitrifying bacteria. Additionally, several genera with heavy metal tolerance, such as Burkholderia-Caballeronia-Paraburkholderia, Delftia, Methylversatilis, Aquicella, and Ralstonia, were widely distributed in the leachate, indicating the strong adaptive capacity of the microbial population. A correlation analysis between the hydrochemical factors and the microbial community structure revealed that pH was the most influential factor, followed by NO2--N, Fe, Al, Cu, Mn, and others. These results indicate that acidification modifies the hydrochemical conditions of the aquifer, creating an environment that is unfavorable for microbial growth and survival. However, some microorganisms may acquire resistance genes to cope with environmental changes.

Isolation and Identification of Arsenic-Resistant Extremophilic Bacteria from the Crater-Lake Volcano "El Chichon", Mexico

The crater lake at "El Chichón" volcano is an extreme acid-thermal environment with high concentrations of heavy metals. In this study, two bacterial strains with the ability to resist high concentrations of arsenic (As) were isolated from water samples from the crater lake. Staphylococcus ARSC1-P and Stenotrophomonas ARSC2-V isolates were identified by use of the 16S rDNA gene. Staphylococcus ARSC1-P was able to grow in 400 mM of arsenate [As(V)] under oxic and anoxic conditions. The IC₅₀ values were 36 and 382 mM for oxic and anoxic conditions, respectively. For its part, Stenotrophomonas ARSC2-V showed IC₅₀ values of 110 mM and 2.15 for As(V) and arsenite [As(III)], respectively. Arsenic accumulated intracellularly in both species [11-25 nmol As × mg cellular prot^-1 in cells cultured in 50 mM As(V)]. The present study shows evidence of microbes that can potentially be a resource for the bio-treatment of arsenic in contaminated sites, which highlights the importance of the "El Chichón" volcano as a source of bacterial strains that are adaptable to extreme conditions.

Metagenome based analysis of groundwater from arsenic contaminated sites of West Bengal revealed community diversity and their metabolic potential

The study of microbial community in groundwater systems is considered to be essential to improve our understanding of arsenic (As) biogeochemical cycling in aquifers, mainly as it relates to the fate and transport of As. The present study was conducted to determine the microbial community composition and its functional potential using As-contaminated groundwater from part of the Bengal Delta Plain (BDP) in West Bengal, India. Geochemical analyses indicated low to moderate dissolved oxygen (0.42-3.02 mg/L), varying As (2.5-311 µg/L) and Fe (0.19-1.2 mg/L) content, while low concentrations of total organic carbon (TOC), total inorganic carbon (TIC), nitrate, and sulfate were detected. Proteobacteria was the most abundant phylum, while the indiscriminate presence of an array of archaeal phyla, Euryarchaeota, Crenarchaeota, Nanoarchaeota, etc., was noteworthy. The core community members were affiliated to Sideroxydans, Acidovorax, Pseudoxanthomonas, Brevundimonas, etc. However, diversity assessed over multiple seasons indicated a shift from Sideroxydans to Pseudomonas or Brevundimonas dominant community, suggestive of microbial response to seasonally fluctuating geochemical stimuli. Taxonomy-based functional potential showed prospects for As biotransformation, methanogenesis, sulfate respiration, denitrification, etc. Thus, this study strengthened existing reports from this region by capturing the less abundant or difficult-to-culture taxa collectively forming a major fraction of the microbial community.

Genome-Resolved Metagenomics and Metatranscriptomics Reveal that Aquificae Dominates Arsenate Reduction in Tengchong Geothermal Springs

Elevated arsenic (As) is common in geothermal springs, shaping the evolution of As metabolism genes and As transforming microbes. Herein, genome-level microbial metabolisms and As cycling strategies in Tengchong geothermal springs were demonstrated for the first time based on metagenomic and metatranscriptomic analyses. Sulfur cycling was dominated by Aquificae oxidizing thiosulfate via the sox system, fueling the respiration and carbon dioxide fixation processes. Arsenate reduction via arsC [488.63 ± 271.60 transcripts per million (TPM)] and arsenite efflux via arsB (442.98 ± 284.81 TPM) were the primary detoxification pathway, with most genes and transcripts contributed by the members in phylum Aquificae. A complete arsenotrophic cycle was also transcriptionally active as evidenced by the detection of aioA transcripts and arrA transcript reads mapped onto metagenome-assembled genomes (MAGs) affiliated with Crenarchaeota. MAGs affiliated with Aquificae had great potential of reducing arsenate via arsC and fixing nitrogen and carbon dioxide via nifDHK and reductive tricarboxylic acid (rTCA) cycle, respectively. Aquificae's arsenate reduction potential via arsC was observed for the first time at the transcriptional level. This study expands the diversity of the arsC-based arsenate-reducing community and highlights the importance of Aquificae to As biogeochemistry.

Geochemical and microbiological profiles in hydrothermal extreme acidic environments (Pisciarelli Spring, Campi Flegrei, Italy)

Although terrestrial hydrothermal systems are considered among the most fascinating environments, how their unique and extreme conditions can affect microorganisms selection and the role in biogeochemical cycles has not yet been well elucidated. A combined geochemical and microbiological exploration in waters and sediments from ten sampling points along a sharp temperature gradient (15-90 °C) within an extremely acidic hydrothermal system (Pisciarelli Spring, Campi Flegrei area, southern Italy) displayed how hydrothermal fluids influence the microbial dynamics. This area was characterized by high levels of reduced gaseous species (e.g. H2S, H2, CH4, CO), and very low pH values (<2.3). Thermodynamic calculations revealed a high microbial catabolic potential in oxidation/reduction reactions of N-, S-, and Fe-bearing species. Overall, an increase of the archaeal/bacterial abundance ratio was observed by decreasing temperature and pH values. In particular, Archaea and Bacteria were present in almost equal cell abundance (up to 1.1 × 109 and 9.3 × 108 cell/g, respectively) in the <70 °C sampling points (average pH = 2.09); on the contrary, highest temperature waters (85-90 °C; average pH = 2.26) were characterized by low abundance of archaeal cells. The high-throughput sequencing of 16S rRNA gene indicated strong differences in archaeal and bacterial communities' composition along temperature gradient. However, the microbiome in this extreme environment was mainly constituted by chemoautotrophic microorganisms that were likely involved in N-, S-, and Fe-bearing species transformations (e.g. Acidianus infernus, Ferroplasma acidarmanus, Acidithiobacillus, Sulfobacillus, Thaumarchaeota), in agreement with thermodynamic calculations.

Different Regulatory Strategies of Arsenite Oxidation by Two Isolated Thermus tengchongensis Strains From Hot Springs

Arsenic is a ubiquitous constituent in geothermal fluids. Thermophiles represented by Thermus play vital roles in its transformation in geothermal fluids. In this study, two Thermus tengchongensis strains, named as 15Y and 15W, were isolated from arsenic-rich geothermal springs and found different arsenite oxidation behaviors with different oxidation strategies. Arsenite oxidation of both strains occurred at different growth stages, and two enzyme-catalyzed reaction kinetic models were observed. The arsenite oxidase of Thermus strain 15W performed better oxidation activity, exhibiting typical Michaelis–Menten kinetics. The kinetic parameter of arsenite oxidation in whole cell showed a V_max of 18.48 μM min^–1 and K_M of 343 μM. Both of them possessed the arsenite oxidase-coding genes aioB and aioA. However, the expression of gene aioBA was constitutive in strain 15W, whereas it was induced by arsenite in strain 15Y. Furthermore, strain 15Y harbored an intact aio operon including the regulatory gene of the ArsR family, whereas a genetic inversion of an around 128-kbp fragment produced the inactivation of this regulator in strain 15W, leading to the constitutive expression of aioBA genes. This study provides a valuable insight into the adaption of thermophiles to extreme environments.

When FLOW-FISH met FACS: Combining multiparametric, dynamic approaches for microbial single-cell research in the total environment

In environmental microbiology, the ability to assess, in a high-throughput way, single-cells within microbial communities is key to understand their heterogeneity. Fluorescence in situ hybridization (FISH) uses fluorescently labeled oligonucleotide probes to detect, identify, and quantify single cells of specific taxonomic groups. The combination of Flow Cytometry (FLOW) with FISH (FLOW-FISH) enables high-throughput quantification of complex whole cell populations, which when associated with fluorescence-activated cell sorting (FACS) enables sorting of target microorganisms. These sorted cells may be investigated in many ways, for instance opening new avenues for cytomics at a single-cell scale. In this review, an overview of FISH and FLOW methodologies is provided, addressing conventional methods, signal amplification approaches, common fluorophores for cell physiology parameters evaluation, and model variation techniques as well. The coupling of FLOW-FISH-FACS is explored in the context of different downstream applications of sorted cells. Current and emerging applications in environmental microbiology to outline the interactions and processes of complex microbial communities within soil, water, animal microbiota, polymicrobial biofilms, and food samples, are described.

Adaptation of Microbial Communities to Environmental Arsenic and Selection of Arsenite-Oxidizing Bacteria From Contaminated Groundwaters

Arsenic mobilization in groundwater systems is driven by a variety of functionally diverse microorganisms and complex interconnections between different physicochemical factors. In order to unravel this great ecosystem complexity, groundwaters with varying background concentrations and speciation of arsenic were considered in the Po Plain (Northern Italy), one of the most populated areas in Europe affected by metalloid contamination. High-throughput Illumina 16S rRNA gene sequencing, CARD-FISH and enrichment of arsenic-transforming consortia showed that among the analyzed groundwaters, diverse microbial communities were present, both in terms of diversity and functionality. Oxidized inorganic arsenic [arsenite, As(III)] was the main driver that shaped each community. Several uncharacterized members of the genus Pseudomonas, putatively involved in metalloid transformation, were revealed in situ in the most contaminated samples. With a cultivation approach, arsenic metabolisms potentially active at the site were evidenced. In chemolithoautotrophic conditions, As(III) oxidation rate linearly correlated to As(III) concentration measured at the parental sites, suggesting that local As(III) concentration was a relevant factor that selected for As(III)-oxidizing bacterial populations. In view of the exploitation of these As(III)-oxidizing consortia in biotechnology-based arsenic bioremediation actions, these results suggest that contaminated aquifers in Northern Italy host unexplored microbial populations that provide essential ecosystem services.

Characterization of Arsenite-Oxidizing Bacteria Isolated from Arsenic-Rich Sediments, Atacama Desert, Chile

Arsenic (As), a semimetal toxic for humans, is commonly associated with serious health problems. The most common form of massive and chronic exposure to As is through consumption of contaminated drinking water. This study aimed to isolate an As resistant bacterial strain to characterize its ability to oxidize As (III) when immobilized in an activated carbon batch bioreactor and to evaluate its potential to be used in biological treatments to remediate As contaminated waters. The diversity of bacterial communities from sediments of the As-rich Camarones River, Atacama Desert, Chile, was evaluated by Illumina sequencing. Dominant taxonomic groups (>1%) isolated were affiliated with Proteobacteria and Firmicutes. A high As-resistant bacterium was selected (Pseudomonas migulae VC-19 strain) and the presence of aio gene in it was investigated. Arsenite detoxification activity by this bacterial strain was determined by HPLC/HG/AAS. Particularly when immobilized on activated carbon, P. migulae VC-19 showed high rates of As(III) conversion (100% oxidized after 36 h of incubation). To the best of our knowledge, this is the first report of a P. migulae arsenite oxidizing strain that is promising for biotechnological application in the treatment of arsenic contaminated waters.

Comprehensive insights into arsenic- and iron-redox genes, their taxonomy and associated environmental drivers deciphered by a meta-analysis

In nature, arsenic (As) and iron (Fe) biotransformation are interconnected, influencing local As mobility and toxicity. While As- or Fe-metabolizing microorganisms are widely documented, knowledge concerning their cycling genes, associated with geophysicochemical data and taxonomic distribution, remains scarce. We performed a meta-analysis to explore the distribution and environmental importance of As- and Fe-redox genes (AsRGs and FeRGs) and predict their significant correlations and hosts. The most abundant and ubiquitous AsRGs and FeRGs were arsC and ccoN, respectively. The ccoN gene had the highest frequency at pH ≥ 9.1, in which dissolved Fe(II) is scarce, possibly contributing to enhanced host survival. Fe(III) oxidation genes iro and ccoN appear to be associated with As(V) detoxification in mesophilic environments. No correlation was observed between Fe(III) reduction gene omcB and arsenate reductase genes. Cytochromes with putative roles in Fe-redox reactions were identified (including yceJ and fbcH) and were significantly correlated with As(V) reduction genes under diverse geophysicochemical conditions. The taxonomies of AsRGs and FeRGs-carrying contigs revealed great diversity, among which various, such as Chlamydea (arsC) and Firmicutes (omcB), were previously undescribed. Nearly all (98.9%) of the AsRGs and FeRGs were not carried by any plasmid sequences. This meta-analysis expands our understanding of the global environmental, taxonomic and functional microbiome involved in As- and Fe-redox transformations. Moreover, these findings should help guide studies on putative in vivo functional roles of cytochromes in Fe-redox pathways.

Abundance and diversity of microbial arsenic biotransformation genes in the sludge of full-scale anaerobic digesters from a municipal wastewater treatment plant

Arsenic (As) is a potential contaminant in sewage sludge that may affect waste treatment and limit the use of these waste materials as soil amendments. Anaerobic digestion (AD) is an important and effective process for the treatment of sewage sludge and the chemical speciation of As is particularly important in sludge AD. However, the biotransformation genes of As in sludge during AD has not been fully explored. In this study, the influent and effluent sludge of anaerobic digester in a wastewater treatment plant (WWTP) was collected to investigate the species transformations of As, the abundance and diversity of As biotransformation genes was explored by real-time PCR (qPCR) and metagenomic sequencing, separately. The results showed that arsenite [As(III)] and arsenate [As(V)] were predominant in the influent sludge, whereas the relative abundance of monomethylarsenic acid (MMA) increased by 25.7% after digestion. As biotransformation genes were highly abundant, and the As(III) S-adenosylmethionine methyltransferase (arsM) gene was the predominant which significantly increased after AD by qPCR analysis. Metagenomic analysis indicated that the diversity of the arsM-like sequences also increased significantly after AD. Most of the arsM-like sequences in all the influent and effluent sludge samples were related to Bacteroidetes and Alphaproteobacteria. Furthermore, co-occurrence network analysis indicated a strong correlation between the microbial communities and As. This study provides a direct and reliable reference on As biotransformation genes and microbial community in the AD of sludge.

Bacterial Communities and Functional Genes Stimulated During Anaerobic Arsenite Oxidation and Nitrate Reduction in a Paddy Soil

Microbial arsenite (As(III)) oxidation associated with nitrate (NO₃^-) reduction might be an important process in diminishing arsenic bioavailability and toxicity to rice when paddy soils are contaminated by arsenic. In a noncontaminated soil, however, the responses of bacterial communities and functional genes to As(III) under nitrate-reducing conditions are poorly understood. In this study, anaerobic paddy soil microcosms were established with As(III) and/or NO₃^- to investigate how the bacterial communities and their functional genes were stimulated during As(III) oxidation and nitrate reduction. Microbial oxidation of As(III) to As(V) was substantially accelerated by nitrate addition, while nitrate reduction was not affected by As(III) addition. Metagenomic analysis revealed that nitrate-reducing bacteria were principally affiliated with Pseudogulbenkiania, with narG, nirS, and norBC genes. Putative As(III)-oxidizing bacteria were dominated by an Azoarcus sp. with As(III) oxidase genes aioA and aioB detected in its draft genome, which also had complete sets of denitrification genes (mainly, napA, nirK, and nosZ). Quantitive PCR analysis confirmed that the abundance of Azoarcus spp., aioA, and nosZ genes was enhanced by As(III) addition. These findings suggest the importance of Azoarcus- and Pseudogulbenkiania-related spp., both of which showed various physio-ecological characteristics for arsenic and nitrogen biogeochemistry, in coupling As(III) oxidation and nitrate reduction in flooded paddy soil.

Exploring Biodiversity and Arsenic Metabolism of Microbiota Inhabiting Arsenic-Rich Groundwaters in Northern Italy

Arsenic contamination of groundwater aquifers is an issue of global concern. Among the affected sites, in several Italian groundwater aquifers arsenic levels above the WHO limits for drinking water are present, with consequent issues of public concern. In this study, for the first time, the role of microbial communities in metalloid cycling in groundwater samples from Northern Italy lying on Pleistocene sediments deriving from Alps mountains has been investigated combining environmental genomics and cultivation approaches. 16S rRNA gene libraries revealed a high number of yet uncultured species, which in some of the study sites accounted for more of the 50% of the total community. Sequences related to arsenic-resistant bacteria (arsenate-reducing and arsenite-oxidizing) were abundant in most of the sites, while arsenate-respiring bacteria were negligible. In some of the sites, sulfur-oxidizing bacteria of the genus Sulfuricurvum accounted for more than 50% of the microbial community, whereas iron-cycling bacteria were less represented. In some aquifers, arsenotrophy, growth coupled to autotrophic arsenite oxidation, was suggested by detection of arsenite monooxygenase (aioA) and 1,5-ribulose bisphosphate carboxylase (RuBisCO) cbbL genes of microorganisms belonging to Rhizobiales and Burkholderiales. Enrichment cultures established from sampled groundwaters in laboratory conditions with 1.5 mmol L^-1 of arsenite as sole electron donor were able to oxidize up to 100% of arsenite, suggesting that this metabolism is active in groundwaters. The presence of heterotrophic arsenic resistant bacteria was confirmed by enrichment cultures in most of the sites. The overall results provided a first overview of the microorganisms inhabiting arsenic-contaminated aquifers in Northern Italy and suggested the importance of sulfur-cycling bacteria in the biogeochemistry of arsenic in these ecosystems. The presence of active arsenite-oxidizing bacteria indicates that biological oxidation of arsenite, in combination with arsenate-adsorbing materials, could be employed for metalloid removal.

Population Structure and Morphotype Analysis of "Candidatus Accumulibacter" Using Fluorescence In Situ Hybridization-Staining-Flow Cytometry

"Candidatus Accumulibacter" is the dominant polyphosphate-accumulating organism (PAO) in denitrifying phosphorus removal (DPR) systems. In order to investigate the community structure and clade morphotypes of "Candidatus Accumulibacter" in DPR systems through flow cytometry (FCM), denitrifying phosphorus removal of almost 100% using nitrite and nitrate as the electron acceptor was achieved in sequencing batch reactors (SBRs). An optimal method of flow cytometry combined with fluorescence in situ hybridization and SYBR green I staining (FISH-staining-flow cytometry) was developed to quantify PAOs in DPR systems. By setting the width value of FCM, bacterial cells in a sludge sample were divided into three groups in different morphotypes, namely, coccus, coccobacillus, and bacillus. Average percentages that the three different PAO populations accounted for among total bacteria from SBR1 (SBR2) were 42% (45%), 14% (13%), and 4% (2%). FCM showed that the ratios of PAOs to total bacteria in the two reactors were 61% and 59%, and the quantitative PCR (qPCR) results indicated that IIC was the dominant "Candidatus Accumulibacter" clade in both denitrifying phosphorus removal systems, reaching 50% of the total "Candidatus Accumulibacter" bacteria. The subdominant clade in the reactor with nitrite as the electron acceptor was IID, accounting for 31% of the total "Candidatus Accumulibacter" bacteria. The FCM and qPCR results suggested that clades IIC and IID were both coccus, clade IIF was coccobacillus, and clade IA was bacillus. FISH analysis also indicated that PAOs were major cocci in the systems. An equivalence test of FCM-based quantification confirmed the accuracy of FISH-staining-flow cytometry, which can meet the quantitative requirements for PAOs in complex activated sludge samples.IMPORTANCE As one group of the most important functional phosphorus removal organisms, "Candidatus Accumulibacter," affiliated with the Rhodocyclus group of the Betaproteobacteria, is a widely recognized and studied PAO in the field of biological wastewater treatment. The morphotypes and population structure of clade-level "Candidatus Accumulibacter" were studied through novel FISH-staining-flow cytometry, which involved denitrifying phosphorus removal (DPR) achieving carbon and energy savings and simultaneous removal of N and P, thus inferring the different denitrifying phosphorus removal abilities of these clades. Additionally, based on this method, in situ quantification for specific polyphosphate-accumulating organisms (PAOs) enables a more efficient process and more accurate result. The establishment of FISH-staining-flow cytometry makes cell sorting of clade-level noncultivated organisms available.

Disentangling natural and anthropogenic impacts on groundwater by hydrogeochemical, isotopic and microbiological data: Hints from a municipal solid waste landfill

Within human-impacted areas, high levels of inorganic compounds in groundwater are broadly and preventively attributed to local anthropogenic pollution, thoroughly disregarding geogenic natural background levels. Particularly in landfills, a proper evaluation of the significant adverse environmental effects should be completed through a detailed groundwater characterization, and appropriate reference values established prior to landfill onset. However, the monitoring network may lack a full hydrogeological representativeness of the site and of the background conditions of groundwater. This study aimed at disentangling natural and anthropogenic impacts through a synoptic analysis of hydrogeochemical, isotopic and microbiological characteristics of groundwaters from a municipal solid waste landfill area in Central Italy. Samples were collected during four seasonal monitoring surveys from the mostly anoxic aquifer underlying the target area. Field parameters, inorganic and organic compounds, environmental isotopes, faecal contamination, and microbial community characteristics were determined, along with a detailed hydrogeological conceptual model. Key inorganic contaminants (As, Fe and Mn) exceeded the local threshold values in most of the sampling points, while organic contamination was generally very low. Stable isotopes suggested that groundwater originated mainly from local rainfall, except at one monitoring points where tritium levels might indicate moderate impact. Microbiological data and the microbial community characterization, assessed by flow cytometry and BIOLOG assays, provided further supportive information, also highlighting fundamental effects of groundwater quality alterations. Overall, an integrated multi-parametric approach proved suitable to distinguish geogenic and anthropogenic impacts, thus improving strategies and schemes for protection and management of groundwaters in landfills and waste related industrial areas.