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Nutrient recovery from urine can contribute to sustainable crop production. However, the efficient reuse of adsorbed nutrients depends on their bioavailability, a characteristic that is typically disregarded. In this study, Ca(OH)2-treated zeolite (CaT-Zeol) and palygorskite (CaT-Pal) were compared as one-time adsorbents of PO4-P and NH4-N in aqueous solutions and real human urine. Desorption tests were conducted to determine the real solid concentration of nutrients after adsorption in fresh (FU) and hydrolyzed urine (HU). They revealed that (i) CaT-Zeol immobilized more P (6.27–6.79 mg/g) than CaT-Pal (5.35–5.68 mg/g), and (ii) drying the loaded adsorbents at 35 or 105 °C slightly affected the total P desorption. Both materials adsorbed less P from the alkaline HU (1.92 mg/g CaT-Zeol and 0.50 mg/g CaT-Pal) than from the slightly acidic FU. The calcium-bound P predominated on the FU-loaded adsorbents, followed by the plant-available NaHCO3-P. Compared to the CaT-Pal (0.09–0.61 mg N/g), the desorption of plant-available NH4-N from the FU- and HU-loaded CaT-Zeol (1.72–8.07 mg N/g) was significantly higher. SEM–EDS analyses confirmed the formation of calcium phosphate phases on the FU-loaded adsorbents. The IR-ATR spectra indicated the NH4-N presence on the FU- and HU-loaded CaT-Zeol as well as the phosphate adsorption via ligand exchange on both geosorbents. In conclusion, both materials are better suited for P adsorption in FU than in HU, with CaT-Zeol being more effective than CaT-Pal as a dual adsorbent in FU and HU. The overall findings demonstrate the upgrade of both soil-friendly materials after adsorbing plant-available nutrients. [ABSTRACT FROM AUTHOR]

Ophicalcites exposed on the island of Tinos, Greece, occur as ellipsoidal bodies within greenschist-facies phyllites of the Upper Cycladic Unit. Close to their outcrops, blocks of serpentinites, metabasic rocks and metasediments were identified, implying a tectonically dismembered ophiolitic sequence in the study area. The ophicalcites comprise brecciated serpentinites cemented by calcite. Based on textural, mineralogical and deformation features, five ophicalcite varieties were discriminated, reflecting calcite precipitation, sedimentary features and increasing brecciation. Serpentinitic fragments comprise antigorite, while Cr-spinel, magnetite, talc and chlorite are accessory minerals. Carbonate veins consist of calcite and minor dolomite, talc, chlorite, and rarely epidote. Bulk rock chemical compositions and Cr-spinel mineral composition point towards a supra-subduction environment. Carbon and oxygen isotope ratios of calcite imply precipitation from mixed marine and hydrothermal fluids, followed by isotope exchange due to late, greenschist-facies overprint. The Tinos ophicalcites record intraoceanic exhumation of the ultramafics at the seafloor, where faulting and serpentinization caused an extensive network of fractures, healed by carbonates. Such intraoceanic deformation can be attributed either to obduction tectonics expressed by thrusting of oceanic piles, or to transpressional(?) transform faults, or more probably to slip along detachment fault of an oceanic core complex. [ABSTRACT FROM AUTHOR]

cervelleite-like mineral, two unnamed silver sulfotellurides in the system Ag-Cu-Te-S [AgCuTeS, (Ag,Cu)TeS], Te-rich polybasite and cadmian tetrahedrite occur in gold-bearing quartz veins in metapelites and faults within brecciated marbles of the Cycladic Blueschist Unit in the Kallianou area (southern Evia Island, Greece). The quartz veins and faults are discordant to syn-metamorphic structures and formed during ductile to brittle deformation in the final stages of exhumation of the Styra Nappe extrusion wedge (~21 Ma). Te-rich polybasite (up to 7.4 wt. % Te), cadmian tetrahedrite (up to 12.4 wt. % Cd), together with electrum (23-54 wt. % Ag) and the sulfotellurides, are the main silver carriers in the mineralization. The two unnamed sulfotellurides, AgCuTeS and (Ag,Cu)TeS are believed to be new quaternary minerals in the system Ag-Cu-Te-S. These minerals and the cervelleite-like phase could have exsolved from galena during cooling (below 200°C). Initial temperatures for the formation of the sulfotellurides, in the form of hessite-intermediate solid solution, at Kallianou may be up to 300°C under log fS values between ~ −11.5 to −8.3, and log fTe from ~ −14.8 to −7.8. The values of log fTe and log fS during re-equilibration (at ~200°C) were constrained to −19.5 to −15.2 and to −15.8 to −11.5 respectively. [ABSTRACT FROM AUTHOR]