Q-mode Cluster Analysis Research Articles

Uncovering Foraminiferal assemblages in Pulau Redang and the Importance of FoRAM Index Calibration for Reef Monitoring in South China Sea

To mitigate adverse effects of ocean warming on coral reef degradation, resource managers increasingly explore management and regulation of local stressors to strengthen coral resilience and recovery. Comprehensive assessments and monitoring efforts offer a holistic understanding of reef dynamic ecosystems. In this study, we documented the distribution of benthic foraminiferal assemblages surrounding Pulau Redang, Malaysia, and assessed their potential for monitoring coral reef health using the Foraminifera in Reef Assessment and Monitoring (FoRAM) Index. Undeveloped (R1–R3) and developed (R4–R6) reef sites revealed distinct differences in reef conditions. Foraminiferal distribution showed Amphistegina lessonii (14–34%) as the dominant species, followed by Calcarina hispida (21%) and Calcarina mayori (19%). The Q-mode cluster analysis classified the distribution of foraminiferal assemblages in Pulau Redang into four sub-groups based on the reef ecological conditions. Group A1 and A2, represent the foraminiferal assemblage on the undeveloped west side of the island where live coral cover was >30%. Meanwhile, Group B1 and B2 represent the assemblage found in developed coastal regions with low live coral cover (≤ 20%). Additionally, the CCA results revealed a substantial influence of substrate type on the distribution of benthic foraminifera in the reef environments of Pulau Redang. FoRAM index consistently yielded high values across the study area despite varying coral reef conditions, probably due to the prevalence of Calcarina mayori in mesotrophic reefs (R4–R6), potentially distorting FoRAM values and providing a misleading indicator of reef conditions. The Modified Foram Index (MFI), calculated by excluding calcarinids, classified R3, R4, and R6 as less conducive for reef growth, aligning better with observed reef conditions. We recommend calibrating the FoRAM Index, particularly in mesotrophic reefs where calcarinids dominate foraminiferal assemblages, to enhance its precision and reliability for coral reef health monitoring and assessment within the region.

Miocene Climatic Optimum and Middle Miocene Climate Transition: a foraminiferal record from the central Ross Sea, Antarctica

Abstract. The Ross Sea record of the Miocene Climatic Optimum (MCO; ∼ 16.9–14.7 Ma) and the Middle Miocene Climate Transition (MMCT; ∼ 14.7–13.8 Ma) provides critical insights into Antarctic ocean–cryosphere interactions during a time of extreme warmth and subsequent cooling. Here we report on Lower to Middle Miocene foraminiferal assemblages from the International Ocean Discovery Program (IODP) Site U1521 on the outer shelf of the central Ross Sea to identify regional shifts in environmental and water mass conditions and trace continental shelf evolution. We identified seven benthic biofacies clusters, dominated by abundant Globocassidulina subglobosa (a proposed indicator of proto-Circumpolar Deep Water, pCDW), Uvigerina cf. U. fueguina (high productivity and enhanced bottom-water currents), Nonionella spp. (high productivity), or Melonis spp. (high productivity) using a Q-mode cluster analysis to develop preliminary regional paleoenvironmental interpretations. Four unique assemblages, including Globobulimina cf. G. auriculata (high productivity and low oxygen), are also identified. Unit IV (representing the early MCO event) is a short-lived (∼ 80 ka), progradational, clast-poor sandy diamictite, likely deposited during deglaciation; the upper part of Unit IV is transitional with overlying Unit III. Unit IV sediments contain the most persistently abundant and diverse foraminiferal assemblages recovered at U1521 because they are mud-rich and diatom-poor, despite very high sedimentation rates. The benthic assemblages shift between Globocassidulina and Uvigerina dominance, suggesting changes in the pCDW influence relative to productivity and/or current activity. We suggest the abundance of Uvigerina (a shelf-edge proxy) in Unit IV records the northward progradation of the Ross continental shelf at this location during the late Early to Middle Miocene. Unit III (MCO) was deposited in an open-marine setting, evident by the ice-rafted detritus or debris (IRD) clast-free, diatom-rich/diatom-bearing muds. The sporadic nature of foraminiferal abundances in Unit III is likely due to intervals of terrigenous mud alternating with more diatom-rich/diatom-bearing muds. As in Unit IV, the muddier lithologies (higher natural gamma ray (NGR) values) are more likely to preserve calcareous foraminifera, whereas the most diatom-rich sediments (lower NGR values) are more corrosive to carbonate. We interpret the muddier intervals as interglacials with incursions of pCDW, as indicated by increased Globocassidulina subglobosa, and sporadic occurrences of rare warmer-water planktic foraminifera. Collectively, these multiple incursions of warmer-water planktic foraminifera provide evidence for polar amplification in the Ross Sea during the MCO and MMCT. The diatom-rich muds are interpreted as glacials during the MCO with open-marine conditions and higher productivity. The dominance of Globobulimina in the upper part of Unit III corresponds with the carbon maximum of Carbon Maxima 2 (CM2) and low-oxygen conditions in the sediments at ∼ 16.1 Ma. Subsequent glaciation (including Mi2, Miocene Isotope event 2), marine-based ice sheet grounding, and erosion on the shallow shelf are recorded by the widespread Ross Sea Unconformity 4 (RSU4; ∼ 15.95–14.2 Ma) at Site U1521. Unit II (MMCT) likely represents sedimentation in the interval between the RSU4 and the Mi3 (Miocene Isotope event 3) glaciation at ∼ 13.9–13.8 Ma. The benthic biofacies composition of Unit II shows a further increase in neritic taxa, including Elphidium magellanicum and Epistominella vitrea, suggesting continued shoaling of the continental shelf, which facilitated the growth of marine-based ice sheets during the Middle Miocene. Our initial correlation between Site U1521 and the ANtarctic geological DRILLing Project (ANDRILL) site, AND-2A, yields similar environmental interpretations, including peak warm events 3 and 4 during the MCO, supported by the foraminifera and unit lithologies. Suspected glacial intervals during the MCO, including Mi2 at the top of Unit III, correlate well with the reconstructed deep-sea estimates of ice volume changes (seawater δ18Osw record) from the Ocean Drilling Program (ODP) Site 1171 on the South Tasman Rise.

Middle Eocene Nannofossil Assemblages Responding to Depositional Dynamics of the Elat Formation, Maluku

The Kei Besar Island is mainly composed of the Elat Formation carbonate rocks. This research was conducted to determine the nannofossils assemblages in the Elat Formation to interpret the depositional dynamics during its formation. Lithological observations and sampling for nannofossil analysis were carried out on three measured stratigraphic sections: Section 1 - Hollat, Section 2 - Ngurdu, and Section 3 - Mata Hollat. A total of 47 species assigned to 25 genera of nannofossils were identified in 45 selected samples. The succession of the Elat Formation in the study area formed at NP16 to N17 or Middle Eocene. Stratigraphic reconstruction supported by biostratigraphy analysis shows that Section 3 at the lower (NP16 to NP 17), Section 2 in the middle part (NP 17), and Section 1 at the upper (NP 17). R-mode cluster analysis of nannofossils defined four species clusters (assemblies A, B, C and D) that tend to occur together. Q-mode cluster analysis defined five depth-distribution clusters (1, 2, 3, 4, and 5), each deposited under similar conditions. Based on large foraminifera, the succession was formed in fore reef setting in neritic bathymetric zone. Coarsening and thickening upward supported by the nannofossil assemblages indicate depositional dynamics which tend to be shallower. Reworked fossils, commonly found at the lower of the Elat Formation, show the mechanism of turbid currents in early deposition.

Assessment of Water Quality of Al-Habbaniya Lake by Using Statistical Techniques (Cluster and Factor Analysis)

Habbanyia lake is one of the most crucial resources of water, water lake is used mainly for agriculture, animal activities, and drinking water purposes. In addition, it represents a tourist city. Multivariable statistical approach was used to assess the quality of the water of Habbanyia lake in west Baghdad, to determine how the physical and chemical qualities relate of lake water and the local trend of water type. R-mode and Q-mode cluster and factor analyses were used to categorize chemical characteristics and determine the variables influencing changes in quality. The results show, the water samples are considered to be Fresh water and all the lake water samples were within the WHO standard. In general, Ca-SO4 and Na-SO4 facies were the most prevalent in the Habbanyia Lake water. The results show, there are two factors controlling the water quality of Habbanyia lake, the first is geological sitting and the second is human activities.

Impact of thermal water on environment case study of Mila and Guelma region, Algeria

A hydrochemical characterization of the waters of the study region (North-East Algeria) was carried out following samples taken at 36 thermal springs and their effluents during May 2022. The analysis of the waters allowed to establish the chemical facies and their classification according to the Stuyfzand's method and to deduce the aptitude of these waters for irrigation and the risks of salinity. The results revealed physico-chemical characteristics, relatively, variable. Q-mode cluster analysis was applied to the thermal water, generated four (4) groups clusters. Group1 represent a group of waters with low salinity dominatedby Na-HCO3; Stuyfzand's classification indicated that the waters are fresh-brackish with moderate to moderately high alkalinity. Taking into account the classification of Richards; we were able to identify the presence of the C3S1 class for the majority of the stations. The C3S1 class designates waters that can be used without any particular control for the irrigation of crops that are moderately tolerant to salts. These waters have average EC values of 3616.3µS/cm allowing their use in a less restrictive way for irrigation. Potential environmental effluents from the thermal spas could pollute both irrigation and drinking water, which represents a danger to the health of the region's inhabitants.

Distribution of Foraminiferal Assemblages in Contemporary Bottom Sediments of Qua-Iboe River Estuary, Southeast Nigeria

Abstract Qua-Iboe River estuary, Southeast Nigeria, was studied to determine the relationship between foraminiferal distribution and bottom water physicochemical parameters including salinity, temperature, depth, dissolved oxygen, pH, tidal energy, and sediment. Fifty-five bottom sediment samples from geo-referenced stations were collected at water depths of 0–10 m across the channel. Ten species of foraminifera were identified in the estuary. Q-mode cluster analysis resulted in two biotopes (1 and 2), each representing distinct sub-environments. Biotope 1 included two sub-groups namely, 1a and 1b. Biotope 1a represents the upper estuary environment and is distinguished by the non-recovery of foraminifera. It has a maximum water depth of 8.3 m and occurs in freshwater conditions (0 ppt) with slightly acidic to neutral pH and fine- to medium-grained sands. Biotope 1b is found in the mid-estuarine environment and has a maximum water depth of 4 m. It is distinguished by an abundance of Arenoparrella mexicana. Biotope 2 occurs within the subtidal lower estuarine environment with a maximum water depth of 4 m. It is characterized by slightly acidic to slightly alkaline (pH = 6–8), brackish to marine waters, with fine to very fine-grained sands. Foraminiferal species commonly found in this biotope include Ammonia beccarii, Pseudononion japonicum, and Cribroelphidium excavatum. As salinity increased seawards, agglutinated taxa were gradually replaced by calcareous species. Foraminiferal assemblages in bottom sediments are strongly influenced by salinity.

Hydro-geochemical investigations of arsenic rich groundwater using multivariate statistical analysis

Multivariate statistical analysis has been applied to assess the chemical characteristics of high arsenic groundwater from the central-southern part of Bangladesh. A total of 43 shallow ground-water samples were collected and analyzed. The groundwater is almost neutral. The results of cations and anions trends are Na>Ca>Mg>K and HCO3>Cl>SO4>NO3, respectively. Alkalinity has a significant positive correlation with Mg, Ca and K suggesting silicate weathering as the major process of controlling groundwater geochemistry. The significant positive correlation between Na and Cl indicates the seawater intrusion into groundwater. The R-mode cluster al-lows variables into four groups. Alkalinity, Mg, K in the first and Ca in the second, Na and Cl in the third cluster indicate silicate weathering and carbonate dissolution and seawater intrusion, respectively. R-mode factor analysis allows variables into four components having eigen values more than 1 which represent 72.5% of total variances. Component 1 positively loaded with K, Mg, P, and alkalinity suggest silicate weathering. Component 2 positively loaded with Na and Cl suggests seawater influences groundwater. Component 3 positively loaded with Ca suggest the carbonate dissolution. The Q-mode cluster analysis represents the highest Fe concentrations.

Paleoecological and paleobiogeographical inferences of the Paleocene ostracods from Sinai, Egypt

The present study aims to detect the paleoecology and paleobiogeography of the Paleocene ostracods from Sinai, Egypt. In order to reach our goals, the Paleocene rocks were examined in four outcrops (El Dokh, El Qussaima, Matulla, and Ekma sections) from Sinai, Egypt. The recognized rock units include Dakhla Formation (at the base) and Tarawan Formation (at the top). The investigation of the ostracod fauna yielded 49 species and subspecies, which enabled the recognition of one Paleocene biozone, Mauritsina teiskotensis - Ordoniya ordoniya Zone. The Early and Middle Paleocene have diverse assemblages, while the Late Paleocene showed a rarity of ostracods. Based on the shape of the carapaces and the surface ornamentation, four ostracod morphogroups were recognized. Morphogroup 4 is the most common group in all the studied sections. The structure of ostracod assemblages (abundance, richness and the morphogroups) besides the lithology pointed out to middle - outer neritic depositional environment for the studied Paleocene sections. The identified species have a wide geographic range, extending from West Africa, North africa to the Middle East. The paleobiogeographic framework is carried out with the aid of multivariate analyses. The suggested matrix consists of 25 ostracod species from 10 countries, including Egypt, Libya, Tunisia, Algeria, Jordan, Israel, Senegal, Ivory Coast, Niger and Mali. The outcomes of the Q-mode cluster analysis indicate that the selected countries may be categorized into three provinces, North Africa (Libya, Algeria, Tunisia and Egypt), West Africa (Senegal, Mali, Ivory Coast and Niger), and Middle East (Israel and Jordan). The similarity of ostracod assemblages between North Africa, including Egypt, with that of Jordan and Israel, suggests the migration and exchange through the southern Tethyan coast. The common deep marine species between North and West Africa may be migrated along the West African coast on the Atlantic Ocean, while shallow species migrated through the trans-Saharan seaway.

Spatio-temporal variation of groundwater hydrochemistry and suitability for drinking and irrigation in Arba Minch Town, Ethiopia: An integrated approach using water quality index, multivariate statistics, and GIS

Groundwater is a pivotal natural resource in and around Arba Minch Town (AMT), Ethiopia. It has become a necessary resource over the past years due to the increase in its usage for drinking, irrigation, and industrial uses. Therefore, a hydro-chemical characterization and assessment of groundwater quality in the AMT was carried out using GIS, Groundwater Quality Index (GWQI), and multivariate statistical methods (MSM). This research attempted to identify the concentrations and spatial dispersal of various ions, the appropriateness of groundwater, and the hydrochemical processes that contribute to its chemistry. During both seasons, the major cations and anions in the groundwater are in the following order: Ca2+ > Na+ > Mg2+ > K+; HCO3 > SO4 > Cl− > NO3 > F-. Four principal components (PC1, PC2, PC3, and PC4) accounted for 86.65% and 85.36% of the total variance during the dry and wet seasons, respectively. For both seasons, Q-mode cluster analysis identified four significant clusters in the groundwater samples. The GWQI revealed that a majority of the samples fall into the good to excellent category of water, implying that the water is safe to drink and use for other domestic purposes. Consequently, based on the Sodium Adsorption Ratio (SAR), Sodium Percentage (Na+ %), and Residual Sodium Carbonate (RSC) values of groundwater samples, analysis shows that most groundwater samples are appropriate for agrarian. The Ca2+–Mg2+–HCO3 water type is the dominant groundwater type, indicating temporary hardness. The interaction of rock water and evaporation processes are the two major natural mechanisms that control the chemistry of groundwater. This study will help planners better manage groundwater resources in this town in the future.

Relationship between Modern Deep-Sea Ostracods and Water Mass Structure in East Antarctica

This study investigated the relationship between the distribution of modern ostracod biofacies and environmental factors in Lützow–Holm Bay, off Cape Darnley, and off Totten Glacier in East Antarctica. We collected study samples from water depths of 219 to 987 m by the 61st Japanese Antarctic Research Expedition. Nineteen species belonging to 13 genera and 47 species belonging to 31 genera of ostracods were found in three samples from Lützow–Holm Bay and ten samples from off Totten Glacier, respectively. We found no ostracods in the samples off Cape Darnley. Q-mode cluster analysis reveals four ostracod biofacies (A to D). Antarctiloxoconcha frigida (Neale, 1967) and Australicythere polylyca (Müller, 1908) were common under the influence of cold water in the upper bathyal zone (biofacies A to C). The genus Krithe was the most abundant taxon in biofacies D with low dissolved oxygen and high-water temperature (0.38°C, 34.66, and 5.0 ml/L, respectively), indicating the presence of warm deep seawater, i.e., modified Circumpolar Deep Water. Thus, we have checked the relationships between the ostracod assemblages and the environmental parameters analyzed in Lützow–Holm Bay and off Totten Glacier, and so strengthened the previous ostracod and environmental data.

Potential hydraulic connectivity of coal mine aquifers based on statistical analysis of hydrogeochemistry

Mining activities interfere with the natural groundwater chemical environment, which may lead to hydrogeochemical changes of aquifers and mine water inrush disasters. This study analyzed the hydrochemical compositions of 80 water samples in three aquifers and developed a water source identification model to explore the control factors and potential hydraulic connection of groundwater chemistry in a coal mine. The results showed that the hydrochemical types of the three aquifers were different. The main hydrochemical compositions of the loose-layer, coal-bearing, and limestone aquifers were HCO3·Cl–Na, SO4·HCO3–Na, and SO4–Na·Ca, respectively. The correlation, Unmix, and factor analyses showed that the hydrochemical composition of groundwater was controlled by the dissolution of soluble minerals (such as calcite, dolomite, gypsum, and halite) and the weathering of silicate minerals. The factor score plot combined with Q-mode cluster analysis demonstrated no remarkable hydraulic connection among the three aquifers in the study area. The water source identification model effectively identified the source of inrush water. Moreover, the mixing ratio model rationally quantified the contributions of the three aquifers to inrush water.

Integration of Heavy Metal Pollution Indices and Health Risk Assessment of Groundwater in Semi-arid Coastal Aquifers, South Africa

The heavy metal contaminated groundwater results in serious health issues and hence this study attempts to address its sources of contamination using integrated techniques including indexed and statistical methods and its related health hazards. Groundwater pH varied from 5.3 to 8.3 indicating acidic to alkaline in nature. The heavy metal pollution index shows that the groundwater samples vary from low to high pollution class and 21% of the samples exceed the critical limit of 100 implying that they are highly polluted with respect to heavy metals and are unfit for human consumption. The heavy metal evaluation index reveals that all the groundwater samples fall under low pollution. The synthetic pollution index reveals that 2%, 74% and 24% of the samples are suitable, slightly and moderately polluted, respectively, with heavy metals. The water quality index reveals that 19% and 2% of the groundwater samples belong to the poor and very poor water quality category and are spatially situated on the central, northern and southern parts of the study region. Correlation matrix and principal component analysis revealed that weathering of aquifer matrix and anthropogenic activities are accountable for the release of heavy metals into groundwater. Furthermore, R-mode and Q-mode cluster analysis revealed two clusters that are linked to mixed sources including weathering and anthropogenic activities. Based on the hazard quotient, the order of heavy metal impact is Co>Pb>Cd>Zn>As>Mn>Cu>Cr>Fe>Ni for both children and adults. The hazard index values varied from 0.06 to 8.16 for children and from 0.02 to 2.14 for adults. In this study, it is discovered that 43% and 26% of groundwater samples pose a non-carcinogenic health risk in children and adults, respectively. This study highly recommends treatment of contaminated groundwater before consumption in order to protect and maintain public health. The results from this study can be useful for the local municipalities and the policy makers while considering management and mitigation plan to maintain the water quality and to control its adverse effect on human health.

Middle Eocene benthic foraminifera from Qattamiya area, Cairo\u2013Suez district, Egypt: biostratigraphy, paleoecology, and their relation to the Southern and Western Tethyan Provinces

This study deals mainly with the biostratigraphy, paleoecology and paleobiogeogrphy of the Middle Eocene benthic foraminifera from an outcrop exposed at Qattamiya area, Cairo–Suez district, Egypt. This district is covered by relatively thick Eocene sequences composed of limestone intercalated with shales and marl. Stratigraphically, the oldest rock unit exposed in the study area is the Observatory Formation which is followed by the Qurn Formation. The examination of the collected samples led to the recognition of 27 species belonging to 17 genera and 10 families. Three benthic foraminiferal biozones are recognized Elphidium trompi-Quinqueloculina carinata Assemblage Zone, Bulimina jacksonensis Zone, and Quinqueloculina ludwigi Zone. These local biozones are correlated with their equivalents inside Egypt. Therefore, the age is assigned to the Middle Eocene. To detect the paleoecology of the recorded foraminiferal community, some parameters (Foraminiferal abundance, richness, and the percentages of epifaunal and infaunal species) are calculated. Three local paleoecologic ecozones are proposed signifying a hyper-to hyposaline inner neritic environment for the lower part of the Observatory, the middle shelf with low oxygen conditions for the upper part of the Observatory Formation, and hypersaline inner neritic environment for the Qurn Formation. Recently, multivariate analyses are considered as a valuable tool in establishing the paleoecology and paleobiogeographical provinces of the Paleogene microfossils. In this study, a matrix composed of 18 species from six countries (Tunisia, Egypt, Libya, France, Spain and Italy) is suggested for multivariate analyses. This matrix is subjected to the principal component analysis (PCA) and the Q-mode cluster analysis to detect the possible provinces. Consequently, two significant provinces are detected, the Southern Tethyan Province (Tunisia, Libya and Egypt) and the Western Tethyan Province (Spain, Italy, and France). Based on the similarity index, there is a strong similarity between the two provinces, which proposes a marine connection between them during Eocene.

Impact of climate change on mollusks and other invertebrate resources at the Dominican University of California archaeological site (CA-MRN-254), Marin County, California

We have identified and provided ecological interpretations of 30 taxa recovered at two shellmounds at the Dominican University of California archaeology site in Marin County, California (CA-MRN-254). A Q-mode cluster analysis was used to group the samples according to their faunal similarity. The clusters ranged from a diverse grouping of 100 samples with 27 taxa (Cluster A) to those with a more restricted assemblage (4–9 taxa in Clusters B to E). The Q-mode clusters were then used to interpret the variability in food resources utilized through the 1800 years of site occupation. During the Intermediate Middle Period (A.D.100-300), the inhabitants appeared to be selective in the marine taxa they used, evident by the presence of Cluster B and E assemblages. A diverse (Cluster A) assemblage was then utilized at the site at one or both of the shellmounds through the remainder of the occupancy period, including the Middle/Late Period Transition (A.D. 700–900) and Late Period Phase 1C (A.D. 900–1300), coincident with the extensive drought conditions of the Medieval Climatic Anomaly (MCA) in the San Francisco Bay area. These findings suggest the marine invertebrate resources utilized by the site occupants were not significantly affected by the persistent aridity associated with the MCA.

Affinity of the benthic foraminifer Cassidulinoides parkeriana (Brady) for whale-falls: evidence from off western Vancouver Island, British Columbia, Canada

A partial skeleton of a blue or fin whale, estimated to have been 16.5 m in length and thought to have been lying on the seafloor for less than 10 years, was observed at a depth of 1288 m off western Vancouver Island, British Columbia, Canada (48.68 N, 126.84 W). Four push cores were taken at the site, three (15-26 cm in length) directly under caudal vertebrae and one 18 cm long, considered a reference, 15 m away, in order to characterize changes in the benthic foraminiferal assemblage due to the whale-fall. A Q-mode cluster analysis identified four groupings, separating the surface and deeper samples of both the whale-fall and reference cores. The results of a metric multi-dimensional scaling plot and permutational multivariate analysis of variance test of the surface samples also suggest there was a significant difference between the whale-fall and reference core benthic foraminiferal faunas. No endemic species were recovered. Downcore samples below 6 cm in the whale-fall and reference cores were characterized by common Uvigerina peregrina, Pseudoparrella pacifica, Bolivina spissa, Bulimina striata, and Takayanagia delicata. In contrast, Cassidulinoides parkeriana, which typically is a minor component of benthic foraminiferal assemblages, dominated the upper 6 cm of the whale-fall cores, whereas the low oxygen-tolerant species T. delicata dominated the same interval in the reference core. The dramatic increase in abundance of C. parkeriana in the upper sediments below this whale-fall, as well as at the Torishima Seamount whale-fall site off Japan, indicate that it is an opportunistic species well adapted to taking advantage of unpredictable and highly localized tropic windfalls such as whale-falls. To our knowledge, this is the first benthic foraminiferal species shown to increase dramatically in abundance in the presence of a whale-fall. Additionally, modern fragments of whale bones occurring as deep as 12 to 15 cm downcore at the western Vancouver Island site demonstrate the effect of bioturbation by invertebrate scavengers that consume whale carcasses, indicating that detailed biostratigraphic records below whale-falls should be interpreted with caution.

Ecological Constraints of Plankton Bio-Indicators for Water Column Stratification and Productivity: A Case Study of the Holocene North Aegean Sedimentary Record

This study presents novel findings on the drivers of the calcitic planktonic foraminiferal and aragonitic pteropod Holocene assemblages of the North Aegean Trough (northeastern Mediterranean), an area recording the interaction between dynamic water masses as they exchange between the northern and southern Mediterranean sub-basins. Both of these groups of microorganisms are the major producers of calcium carbonate in the ocean, and are particularly sensitive to climate and oceanographic changes over the late Quaternary. Downcore micropaleontological data from the gravity core AEX-15, supplemented with multivariate statistical Q-mode cluster and principal component analyses (PCA) results, provide significant insights on the water column dynamics during the Holocene. Focusing on the last ~10 calibrated thousands of years before the present day (ka cal BP), our integrated study reveals that primary productivity is the dominant factor controlling the planktonic foraminifera distribution in the North Aegean Sea, whereas water column stratification, and particularly the intensity of the oxygen minimum zone, seems to be the major driver on the pteropod distribution. Besides productivity and thermal stratification, which show the highest explanatory power for planktonic foraminifera and pteropod communities, respectively, though they affect both groups to a different extent, upwelling seems to further affect both faunal groups. Overall, our findings are consistent with those derived by published late Quaternary eastern Mediterranean records, highlighting in parallel a useful additional dimension on planktonic foraminiferal and pteropod ecology, which is inextricably linked with the factors of primary productivity and vertical stratification of the warm Holocene water column.

Hydrochemical Characterization of Groundwater Quality in Nkalagu District, Southeastern Nigeria

Hydrochemical characterization of groundwater quality in Nkalagu District, southeastern Nigeria was carried to determine the main factors controlling the chemistry of groundwater and its suitability for drinking and irrigation purposes. Sixty (60) groundwater samples collected from boreholes and hand-dug wells in different parts of the area were analyzed for a range of physiochemical parameters and heavy metal constituents. The results show that concentration of the major ions were in the order Cl->HCO3->SO42->NO3- and Na>Ca2+>Mg2+>K+. The groundwater samples are slightly acidic with pH of 5.28 to 8.04; moderately hard with TH of 112.88 to 467.78 mg/l. The district is mainly controlled by carbonate and silicate mineral weathering based on the available result. Three main flow regimes were identified with Q-mode cluster analysis. Based on the WQIanalysis results, the groundwater quality in the district was classified, generally as ‘poor’ to ‘excellent’ for drinking purpose. Groundwater quality for drinking purpose were noted to deteriorates as one move from west towards the east of the district, while the north and south part pf the study area indicated the best quality in the district. Groundwater quality for irrigation purpose showed excellent quality based on the United States Salinity Laboratory and Wilcox diagrams. For future use of groundwater resource in the district we recommend implementation rules and guidelines in the area to enhance health and preserve groundwater sources in the district.

Statistical analyses of groundwater chemistry in the Qingdong coalmine, northern Anhui province, China: implications for water\u2013rock interaction and water source identification

Hydrochemistry of groundwater is important in coal mines because it can be used for understanding water–rock interaction and inrush water source identification. In this study, major ion concentrations of groundwater samples from the loose layer aquifer (LA), coal-bearing aquifer (CA) and Taiyuan Formation limestone aquifer (TA) in the Qingdong coal mine, northern Anhui province, China, have been analyzed by a series of statistical methods for identifying the source of chemical constituents in groundwater and the source of inrush water. The results indicate that the mean concentration of the major ions in the LA were ordered as follows: HCO3− > SO42− > Na+ + K+ > Cl− > Ca2+ > Mg2+ > CO32−, whereas average values of the CA in decreasing order are SO42−, Na+ + K+, HCO3−, Cl−, Ca2+, Mg2+ and CO32−, and the major ion concentrations of the TA have the following order: SO42− > Na+ + K+ > Ca2+ > HCO3− > Cl− > Mg2+ > CO32−, and most of the samples are Na-SO4 and Ca-SO4 types. TDS content in water increases with aquifer depth, whereas the pH values ranged from 7.1 to 8.9, indicating a weak alkaline environment. Two sources (weathering of silicate minerals and dissolution of evaporate minerals) have been identified by principal component analysis responsible for the chemical variations of the groundwater, and their contribution ratios have been quantified by Unmix model. Moreover, based on the Q-mode cluster and discriminant analyses, the samples with known sources have been identified correctly to be 95.7% and 97.6%, respectively, and the samples with unknown sources have been determined with high probability (78–100%).

Recent Ostracoda from the shelf sediments of Southwestern part of Bay of Bengal: Implication on Microenvironments

A detailed study on Recent Ostracoda was carried out in twenty-six surface sediment samples collected from shelf region of the Southwestern part of Bay of Bengal. A total of 21 species of Ostracoda belonging to 18 genera have been identified, of which, seven species are abundant (>5%). The Q-mode and R-mode cluster analyses of the abundant species resulted in two assemblage defining different microenvironments. The shallowest assemblage (I) from 10 to 80 m water depth is characterised by Hemikrithe Orientalis, Pterygocythereis chennaiensis and Lankacythere multifora which are associated with sand to slightly muddy sand. The second assemblage (II) from 80 to 200 m water depth is associated by Keijella reticulata, Bairdoppilata paraalcyonicola, Actinocythereis scutigera and Stigmatocythere indica and the nature of sediments varies from slightly muddy sand to slightly sandy mud. The sediments from 50-100 m water depth are foundto contain higher concentration of organic matter (TOC and TN) suggesting the high productivity zone. The C/N ratio value ranges from 4 to 8 in 52% of sediment samples indicating both marine and terrestrial source. The shallower part of the seafloor up to 30 m depth is dominated by sandysediments, reflecting the occurence of high-energy conditions. The higher mud content in the deeper part is due to the prevalance of low energy condition. The carapace-valve ratio (1:9) indicates that the study area experiencing a slower rate of sedimentation. Our study results revealed that the distribution of Ostracoda in the Southwestern part of Bay of Bengal is controlled by the type of sediment, depth and physicochemical parameters of the bottom water.

TAFONOMÍA DE LOS CARBONATOS TEMPLADOS PLIOCENOS DE LA CUENCA DE ALMAYATE (MÁLAGA, S DE ESPAÑA)

Se analizan los procesos tafonómicos que afectan a las asociaciones de fósiles de los carbonatos templados del Plioceno que afloran en la Cuenca de Almayate (Málaga, S de España). El estudio tafonómico se ha realizado cuantificando varias propiedades tafonómicas. Los valores obtenidos han servido para realizar un análisis multivariante de agrupamiento de muestras, con objeto de establecer modelos de tafofacies. Los resultados obtenidos indican unas condiciones de depósito de alta energía donde los restos esqueléticos permanecieron durante prolongados períodos de tiempo en la zona tafonómicamente activa. En este contexto, durante los periodos de sedimentación normal se produjo un efecto combinado de destrucción tafonómica: 1) destrucción física, como consecuencia de la alta energía, 2) destrucción biológica, debido al efecto de los organismos bioperforadores, y 3) destrucción química, por disolución de las fases inestables del carbonato cálcico. Estos procesos tafonómicos son los que de forma habitual afectan a los carbonatos templados. Además de estos procesos normales, la acción esporádica de tormentas dejó señales sedimentológicas (presencia de niveles de tempestitas) y tafonómicas propias. En este sentido, el análisis cluster individualiza un conjunto de muestras tomadas en niveles de tempestitas. Finalmente, el análisis cluster separa un tercer grupo de muestras donde domina la presencia de moldes de organismos originalmente aragoníticos sobre restos que mantienen la mineralogía original de la concha. Una cementación temprana debió jugar un papel decisivo en la formación de esta asociación.