Lakes in coastal lowland areas represent a critically vulnerable environment as a transitional space between freshwater and seawater environments. The paleoenvironmental reconstruction and anthropogenic impact are assessed through the lake sediment cores from Velo, Malo, and Kolanjsko Blato using multi-proxy analyses (sedimentological, mineralogical, geochemical, ¹³⁷Cs and ostracod analyses, and AMS ¹⁴C radiocarbon dating). The freshwater lake Velo Blato was formed at 8100 cal yr BP due to rising groundwater levels as a consequence of sea-level rise. The brackish conditions in Lake Velo Blato started at 7100 cal yr BP, giving the index point for the sea-level curve of 7-m lower than present. Lead concentrations showed slightly increased values in the last 1800 cal yr BP, while the spike in Malo Blato lake sediments probably derived from bird hunting with lead bullets. Kolanjsko Blato sediment core archives the sediment record of the last 2050 years, which represents a shallow brackish coastal wetland under marine influence. Enrichment factors showed the accumulation of Cu, Hg, P, Pb, S, and Zn in the sediments from Kolanjsko Blato in the last 650 cal yr BP, which coincides with the high organic carbon content, and in sediments from Malo Blato after the lake’s formation (from the depth of 20 cm upwards). Anthropogenic Cu introduced into the Kolanjsko Blato sediments is the highest in the surface sample. Surficial sediments from Velo Blato are characterized by the high organic carbon, S, P, and N content, indicating high productivity and eutrophication which led to occasional anoxic conditions on the lake bottom in the last 200 years.

Karst poljes in the Dinaric karst are widely infilled with Quaternary sediments. In the Bribir–Ostrovica karst polje, these sediments were investigated using geomorphological mapping and multiproxy analysis of lake sediment cores, including grain size, mineralogical, total organic and inorganic carbon (TOC, TIC), and ostracod analyses, coupled with radiocarbon dating. A key sediment core (OSP-3) recovered a ~470 cm long sedimentary sequence dating back to 13,200 cal yr BP. The floodplain to wetland environment occurred at the Late Pleistocene to Holocene transition (ca. 12,100 cal yr BP), evident by the first appearances of ostracods and an increase in TOC. More stable lake conditions prevailed between 9600 and 7200 cal yr BP, with dominant carbonate deposition and abundant ostracods. During the Middle and Late Holocene, increased clastic input and reduced ostracod presence indicate a shallow, dynamic water body influenced by erosion and periodic flooding. Lake sedimentation was strongly controlled by local karst topography, with a maximum lake depth of ca. 6 m. The Bribir–Ostrovica paleolake represents a rare terrestrial Holocene paleoenvironmental record from the Dinaric karst of the eastern Adriatic coast and provides valuable context for interpreting the nearby Neolithic archaeological site of Krivače as a lakeside settlement.

Karst bauxites represent important archives of paleoenvironmental conditions and potential sources of REE and other critical raw materials (CRMs). This study presents a multiproxy investigation of the Upper Eocene Mamutovac-1a bauxite deposit (Croatian Dinarides), integrating petrography, X-ray diffraction (XRD), magnetic susceptibility, whole-rock geochemistry, and aqua regia extractions along a 25.1 m drill core. The deposit shows clear vertical variability defined by four facies-based zones, accompanied by systematic mineralogical and geochemical changes. The bauxite is dominated by böhmite, gibbsite, hematite, and anatase, with subordinate goethite and clay minerals. ΣREE concentrations range from 276 to 670 mg/kg and increase toward the deeper zones, with consistent LREE enrichment relative to HREE, negative Eu anomalies, and variable Ce anomalies. Correlations suggest that REE are likely associated with phosphate phases, with a possible secondary contribution from clay minerals. The integrated dataset indicates a polygenetic, multi-stage evolution involving both in situ bauxitization and episodic reworking and redeposition, controlled by variable redox conditions and fluid–rock interaction. Geochemical signatures suggest a mixed provenance with contributions from intermediate to ultramafic sources. The elevated concentrations and enhanced extractability of selected elements (La, Sc, Ga, V) indicate that the deposit may represent a potential secondary source of CRMs.