Geochemical processes in recharge basin soils used for municipal effluents reclamation by the soil-aquifer treatment (SAT) system

AbstractThe objective of this study was to analyse spatial variability of the trace elements (TEs) and rare earth elements (REEs) concentration in lake bottom sediments in Bory Tucholskie National Park (BTNP); Poland. The following research questions were posed: which factors have a fundamental impact on the concentration and spatial variability of elements in bottom sediments, which of the elements can be considered as indicators of natural processes and which are related to anthropogenic sources. The research material was sediments samples collected from 19 lakes. The concentrations of 24 TEs and 14 REEs were determined. The analyses were carried out using the inductively coupled plasma mass spectrometry (ICP-QQQ). Cluster analysis and principal component analysis were used to determine the spatial variability of the TEs and REEs concentrations, indicate the elements that are the indicators of natural processes and identify potential anthropogenic sources of pollution. The geochemical background value (GBV) calculations were made using 13 different statistical methods. However, the contamination of bottom sediments was evaluated by means of the index of geo-accumulation, the enrichment factor, the pollution load index, and the metal pollution index. The BTNP area is unique because of its isolation from the inflow of pollutants from anthropogenic sources and a very stable land use structure over the last 200 years. This study shows high variability of TE and REE concentrations in lake sediments. The values of geochemical indices suggest low pollution of lakes bottom sediments. It was found that TEs originated mainly from geogenic sources. However, the concentrations of Li, Ni, Sc, Se, Be, Se, Ag, Re, Tl, Cd, Sb and U may be related to the impact of point sources found mainly in the Ostrowite Lake. Almost all REEs concentrations were strongly correlated and their presence was linked to with geochemical processes. The elements allowing to identify natural processes and anthropogenic pollution sources were Cr, Co, Cu, Ag, Cd, Zn, Bi, Re, Ba, Al and Rb in TEs group and Nd, Gd, Yb, Lu, Eu, Dy and Ce in REEs group. The analysis shows high spatial variability of TE and REE concentrations in lake sediments. The values of geochemical indices point to low pollution of lakes sediments. The anthropogenic sources only for two lakes had an impact on concentrations of selected TEs and REEs. The analyses allowed to identify elements among TEs and REEs documenting geochemical processes and those indicating anthropogenic sources of pollution.

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Characterization of a Shallow Coastal Aquifer in the Framework of a Subsurface Storage and Soil Aquifer Treatment Project Using Electrical Resistivity Tomography (Port de la Selva, Spain)

Applied Sciences ◽

10.3390/app11062448 ◽

2021 ◽

Vol 11 (6) ◽

pp. 2448

Author(s):

Alex Sendrós ◽

Aritz Urruela ◽

Mahjoub Himi ◽

Carlos Alonso ◽

Raúl Lovera ◽

...

Keyword(s):

Electrical Resistivity ◽

Water Reuse ◽

Electrical Resistivity Tomography ◽

Groundwater Modeling ◽

Geophysical Methods ◽

Soil Aquifer Treatment ◽

Modeling Tools ◽

Resistivity Tomography ◽

Implicit Modeling ◽

The Difference

Water percolation through infiltration ponds is creating significant synergies for the broad adoption of water reuse as an additional non-conventional water supply. Despite the apparent simplicity of the soil aquifer treatment (SAT) approaches, the complexity of site-specific hydrogeological conditions and the processes occurring at various scales require an exhaustive understanding of the system’s response. The non-saturated zone and underlying aquifers cannot be considered as a black box, nor accept its characterization from few boreholes not well distributed over the area to be investigated. Electrical resistivity tomography (ERT) is a non-invasive technology, highly responsive to geological heterogeneities that has demonstrated useful to provide the detailed subsurface information required for groundwater modeling. The relationships between the electrical resistivity of the alluvial sediments and the bedrock and the difference in salinity of groundwater highlight the potential of geophysical methods over other more costly subsurface exploration techniques. The results of our research show that ERT coupled with implicit modeling tools provides information that can significantly help to identify aquifer geometry and characterize the saltwater intrusion of shallow alluvial aquifers. The proposed approaches could improve the reliability of groundwater models and the commitment of stakeholders to the benefits of SAT procedures.

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Ion association in hydrothermal aqueous NaCl solutions: Implications for the microscopic structure of supercritical water

Physical Chemistry Chemical Physics ◽

10.1039/d1cp01490k ◽

2021 ◽

Author(s):

Mirko Elbers ◽

Christian Schmidt ◽

Christian Sternemann ◽

Christoph Johannes Sahle ◽

Sandro Jahn ◽

...

Keyword(s):

Supercritical Water ◽

Ion Association ◽

Microscopic Structure ◽

Geochemical Processes ◽

Structure Of Fluids

Knowledge of the microscopic structure of fluids and changes thereof with pressure and temperature is important for the understanding of chemistry and geochemical processes. In this work we investigate the...

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Macro- and Micronutrient Cycling and Crucial Linkages to Geochemical Processes in Mangrove Ecosystems

Journal of Marine Science and Engineering ◽

10.3390/jmse9050456 ◽

2021 ◽

Vol 9 (5) ◽

pp. 456

Author(s):

Daniel M. Alongi

Keyword(s):

Transformation Process ◽

Early Diagenesis ◽

P Availability ◽

Geochemical Processes ◽

Nutrient Cycles ◽

Physiological Mechanisms ◽

Retention Efficiency ◽

Mangrove Ecosystems ◽

N Metabolism ◽

Transformation Processes

High mangrove productivity is sustained by rapid utilization, high retention efficiency and maximum storage of nutrients in leaves, roots, and soils. Rapid microbial transformations and high mineralization efficiencies in tandem with physiological mechanisms conserve scarce nutrients. Macronutrient cycling is interlinked with micronutrient cycling; all nutrient cycles are linked closely to geochemical transformation processes. Mangroves can be N-, P-, Fe-, and Cu-limited; additions of Zn and Mo stimulate early growth until levels above pristine porewater concentrations induce toxicity. Limited nutrient availability is caused by sorption and retention onto iron oxides, clays, and sulfide minerals. Little N is exported as immobilization is the largest transformation process. Mn and S affect N metabolism and photosynthesis via early diagenesis and P availability is coupled to Fe-S redox oscillations. Fe is involved in nitrification, denitrification and anammox, and Mo is involved in NO3− reduction and N2-fixation. Soil Mg, K, Mn, Zn and Ni pool sizes decrease as mangrove primary productivity increases, suggesting increasing uptake and more rapid turnover than in less productive forests. Mangroves may be major contributors to oceanic Mn and Mo cycles, delivering 7.4–12.1 Gmol Mn a−1 to the ocean, which is greater than global riverine input. The global Mo import rate by mangroves corresponds to 15–120% of Mo supply to the oceanic Mo budget.

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