High resolution facies record on late Holocene flood plain sediments from lower reaches of Narmada Valley, Western India

A high resolution quantitative granulometric record for site Uchediya 21A degrees 43'2.22aEuro(3) N, 73A degrees 6'26.22aEuro(3) E; 10 m a. s. l.] gives understanding towards accretion history of the late Holocene flood plain in the lower reaches of Narmada River. Two sediment facies (sandy and muddy) and seven subfacies (sandy subfacies: St(MS+FS+CS), SmFS+MS, Sl(FS+VFS), and St(MS + CS); muddy subfacies: FmSILT+VFS+FS, FmSILT+VFS (O) and FmSILT+VFS (T)) are identified based on cluster analysis supplemented with sedimentary structures observed in field and other laboratory data. Changes in hydrodynamics are further deduced based on various sedimentological parameters and their ratios leading to arrive at a depositional model.

Impact of heavy metals on bacterial communities from mangrove soils of the Mahanadi Delta (India)

This study aimed to assess soil nutrient status and heavy metal content and their impact on the predominant soil bacterial communities of mangroves of the Mahanadi Delta. Mangrove soil of the Mahanadi Delta is slightly acidic and the levels of soil nutrients such as carbon, nitrogen, phosphorous and potash vary with season and site. The seasonal average concentrations (g/g) of various heavy metals were in the range: 14810-63370 (Fe), 2.8-32.6 (Cu), 13.4-55.7 (Ni), 1.8-7.9 (Cd), 16.6-54.7 (Pb), 24.4-132.5 (Zn) and 13.3-48.2 (Co). Among the different heavy metals analysed, Co, Cu and Cd were above their permissible limits, as prescribed by Indian Standards (Co=17g/g, Cu=30 g/g, Cd=3-6 g/g), indicating pollution in the mangrove soil. A viable plate count revealed the presence of different groups of bacteria in the mangrove soil, i.e. heterotrophs, free-living N-2 fixers, nitrifyers, denitrifyers, phosphate solubilisers, cellulose degraders and sulfur oxidisers. Principal component analysis performed using multivariate statistical methods showed a positive relationship between soil nutrients and microbial load. Whereas metal content such as Cu, Co and Ni showed a negative impact on some of the studied soil bacteria.

Do stable isotopes in carbonate cement of Mio-Pleistocene Himalayan sediments record paleoecological and paleoclimatic changes?

Non-pedogenic carbonates, such as carbonate cement and nodules in the sandstones, are quite common in the terrestrial geological record. Unlike pedogenic carbonates, their stable isotope ratios lack investigations for paleo-climatic reconstructions. The present investigation therefore, explores the possibility of use of stable isotope studies of non-pedogenic carbonates from the Mb-Pleistocene Siwalik Group of sediments exposed in the Ramnagar sub-basin of the NW Himalaya. Petrographic studies reveal the dominance of micrite fabric in carbonate nodules both of pedogenic and non-pedogenic samples irrespective of specific stratigraphic unit However, calcite as cement in the sandstones shows the dominance of micrite fabric in the younger in age sediments. Seventy-two non-pedogenic carbonate samples from the carbonate nodules and cement in the Siwalik sandstones, ranging in age between similar to 1 Ma and 12.2 Ma, were analyzed for delta C-13 and delta O-18 values. The delta C-13 values vary from -24.77 parts per thousand to -1.1 parts per thousand and delta O-18 values vary from -15.34 parts per thousand to -7.81 parts per thousand. Pedogenic and non-pedogenic carbonates ranging in age between similar to 1 Ma and 6 Ma have largely similar delta C-13 values and the range of delta C-13 values indicate the dominance of C-4 type of vegetation. However, unlike pedogenic carbonates which showed the dominance of C-3 type of vegetation pre- 7 Ma on the basis of delta C-13 -depleted isotopic values (Singh et al., 2011), delta C-13 values are largely enriched in the corresponding aged non-pedogenic carbonates revealing no information on specific type of vegetation. Likewise, paleoprecipitational reconstructions from delta O-18 values in pedogenic carbonates showed a progressive increase in aridity from similar to 12 Ma to recent excluding short term increases in rainfall/monsoon intensity at around 10 Ma, 5 Ma, and 1.8 Ma (Singh et al., 2012). On the contrary, such reconstructions are not possible from the delta O-18 values of non-pedogenic carbonates and indeed the delta O-18 values of non-pedogenic carbonates are largely depleted to as much as 6 parts per thousand from the corresponding pedogenic carbonates. Such differences in delta C-13 and delta O-18 values of non-pedogenic carbonates from pedogenic carbonates are primarily due to the dependence of the former on groundwater conditions responsible for precipitating carbonate. Further, a comparison of isotopic values between non-pedogenic and pedogenic carbonates can be interpreted that post-6 Ma and pre-6 Ma non-pedogenic carbonates were largely formed by shallow and deep groundwater conditions respectively. The result of these investigative studies therefore, suggests that the stable delta C-13 and delta O-18 values of non-pedogenic carbonates, unlike the pedogenic carbonates and irrespective of nature of calcite fabric, showed their little importance in paleoclimatic and paleoecological reconstructions. (C) 2014 Elsevier B.V. All rights reserved.

Tectono-geomorphic and environmental set-up deduced during deposition of Mio-Pleistocene sediments in NW Himalaya, India

Detailed pedofacies characterization along-with lithofacies investigations of the Mio-Pleistocene Siwalik sediments exposed in the Ramnagar sub-basin have been studied so as to elucidate variability in time and space of fluvial processes and the role of intra- and extra-basinal controls on fluvial sedimentation during the evolution of the Himalayan foreland basin (HFB). Dominance of multiple, moderately to strongly developed palaeosol assemblages during deposition of Lower Siwalik (similar to 12-10.8 Ma) sediments suggest that the HFB was marked by Upland set-up of Thomas et al. (2002). Activity of intra-basinal faults on the uplands and deposition of terminal fans at different times caused the development of multiple soils. Further, detailed pedofacies along-with lithofacies studies indicate prevalence of stable tectonic conditions and development of meandering streams with broad floodplains. However, the Middle Siwalik (similar to 10.8-4.92 Ma) sub-group is marked by multistoried sandstones and minor mudstone and mainly weakly developed palaeosols, indicating deposition by large braided rivers in the form of megafans in a Lowland set-up of Thomas et al. (2002). Significant change in nature and size of rivers from the Lower to Middle Siwalik at similar to 10 Ma is found almost throughout of the basin from Kohat Plateau (Pakistan) to Nepal because the Himalayan orogeny witnessed its greatest tectonic upheaval at this time leading to attainment of great heights by the Himalaya, intensification of the monsoon, development of large rivers systems and a high rate of sedimentation, hereby a major change from the Upland set-up to the Lowland set-up over major parts of the HFB. An interesting geomorphic environmental set-up prevailed in the Ramnagar sub-basin during deposition of the studied Upper Siwalik (similar to 4.92 to <1.68 Ma) sediments as observed from the degree of pedogenesis and the type of palaeosols. In general, the Upper Siwalik sub-group in the Ramnagar sub-basin is subdivided from bottom to top into the Purmandal sandstone (4.92-4.49 Ma), Nagrota (4.49-1.68 Ma) and Boulder Conglomerate (<1.68 Ma) formations on the basis of sedimentological characters and change in dominant lithology. Presence of mudstone, a few thin gravel beds and dominant sandstone lithology with weakly to moderately developed palaeosols in the Purmandal sandstone Fm. indicates deposition by shallow braided fluvial streams. The deposition of mudstone dominant Nagrota Fm. with moderately to some well developed palaeosols and a zone of gleyed palaeosols with laminated mudstones and thin sandstones took place in an environment marked by numerous small lakes, water-logged regions and small streams in an environment just south of the Piedmont zone, perhaps similar to what is happening presently in the Upland region/the Upper Gangetic plain. This area is locally called the `Trai region' (Pascoe, 1964). Deposition of Boulder Conglomerate Fm. took place by gravelly braided river system close to the Himalayan Ranges. Activity along the Main Boundary Fault led to progradation of these environments distal-ward and led to development of on the whole a coarsening upward sequence. (C) 2014 Elsevier B.V. All rights reserved.

Mercury exposure Aasessment in fish and humans from Sundarban Mangrove Wetland of India

Present study had documented total mercury levels in six commonly consumed fish species, and performed across-sectional study on local residents to gauge their intake of fish (via dietary survey) and mercury exposure (via hair biomarker analyses). Mean total mercury content in edible composites of locally-caught fishes (topse, hilsa, mackerel, topse, sardinella, khoira) was low and ranged from 0.01 to 0.11 mu g g(-1) mercury, dry weight. In a cross-sectional study of 58 area residents, the mercury content in hair ranged from 0.25 to 1.23 mu g g(-1), with a mean of 0.65 +/- 0.23 mu g g(-1), Flair mercury level was not influenced by gender, age, or occupation. Mean number of meals consumed per week was 3.1 +/- 1.1, and all participants consumed at least one fish meal per week. When related to fish consumption, a significant positive association was found between number of fish meals consumed per week and hair mercury levels.

Optically Stimulated Luminescence (OSL) Dating of Sediments from Himalaya

Optically Stimulated Luminescence (OSL) dating gives the age of most recent daylight exposure or heating of samples to >400 degrees C or the formation events of authigenic minerals. These correspond to the age of sedimentation and burial, ages of thermal events like contact heating by lava flows and heating during faulting and sand dyke formation, and the formation of a mineral via chemical precipitation. With the first observation of OSL in 1985, this method now occupies centre stage in Quaternary Geochronology. The use of OSL method for sediments from Himalaya began over three decades ago. The method has since provided chronology for a variety of events, such as past glaciation events, formation ages of river terraces, paleo-lacustrine deposits, landslides, floods, seismic events with substantive new insights into timing and style of geological processes. Theoretically, the dating range of method is present to a Million years, and this critically depends on two factors, viz, luminescence properties of mineral and their radiation environments. The general working range using quartz is 200ka, and using feldspars is up to Brunhes Matuyam Boundary. Extensions beyond this limit are currently being explored.

Factors affecting distribution of fish within a tidally drained mangrove forest in the Andaman and Nicobar Islands, India

Mangrove forests in meso-tidal areas are completely drained during low tides, forming only temporary habitats for fish. We hypothesised that in such temporary habitats, where stranding risks are high, distance from tidal creeks that provided access to inundated areas during receding tides would be the primary determinant of fish distribution. Factors such as depth, root density and shade were hypothesised to have secondary effects. We tested these hypotheses in a tidally drained mangrove patch in the Andaman Islands, India. Using stake nets, we measured fish abundance and species richness relative to distance from creeks, root density/m(2), shade, water depth and size (total length) of fish. We also predicted that larger fish (including potential predators) would be closer to creeks, as they faced a greater chance of mortality if stranded. Thus we conducted tethering trials to examine if predation would be greater close to the creeks. Generalised linear mixed effects models showed that fish abundance was negatively influenced by increasing creek distance interacting with fish size and positively influenced by depth. Quantile regression analysis showed that species richness was limited by increasing creek distance. Proportion of predation was greatest close to the creeks (0-25 m) and declined with increasing distance. Abundance was also low very close to the creeks, suggesting that close to the creeks predation pressure may be an important determinant of fish abundance. The overall pattern however indicates that access to permanently inundated areas, may be an important determinant of fish distribution in tidally drained mangrove forests.

Characterization of the sediments overlying the Floridan aquifer system in Alachua County, Florida

The primary purpose of this project is to attempt to improve the existing hydrogeologic information through lithologic and hydrogeologic characterizations of the sediments overlying the Floridan aquifer system in Alachua County. These sediments locally comprise both the intermediate aquifer system and associated confining beds and the surficial aquifer system. (PDF has 119 pages.)

Responses of Hyalella azteca and Ceridaphnia dubia to reservoir sediments following Chelated Copper Herbicide Applications

In response to nuisance growths of algae and vascular plants, such as dioecious hydrilla ( Hydrilla verticillata L.f. Royle), copper formulations have been applied in lakes and reservoirs for a number of years. Concerns have arisen regarding the long-term consequences of copper applications and those concerns have appropriately focused on sediment residues. In this study, we evaluated the toxicity of sediments from treated (for a decade) and untreated areas in Lake Murray, South Carolina and estimated the capacity of those sediments to bind additional copper. Two sentinel aquatic invertebrates, Hyalella azteca Saussure and Ceriodaphnia dubia Richard, were used to measure residual toxicity of treated and untreated sediments from the field and after laboratory amendments. (PDF has 5 pages.)

Distribution and Density of Vegetative Hydrilla Propagules in the Sediments of Two New Zealand Lakes

The distribution and density of hydrilla (Hydrilla verticillata (L.f.)Royle) turions and tubers in two New Zealand lakes were assessed by sampling cores of sediment from Lakes Tutira and Waikapiro each year from 1994 to 1997. Turion and tuber density differed with water depth, with maximum numbers of tubers and turions found in the 1-2 m and 1.5-4m water depth ranges respectively. A high turion to tuber ratio was observed, with turions accounting for over 80% of propagules. The relatively low numbers of turions and tubers compared with other reports, and the distribution of most tubers within the shallow water is likely to be associated with black swan grazing (Cygnus atratus Latham), with maintains a canopy of hydrilla consistently 1 m below the water surface.

Water available in canals and shallow sediments in St. Lucie County, Florida

The increased demand for water placed upon the water resources of St. Lucie County by the expanding agricultural use has brought about hydrologic changes with ensuing problems. This report documents these changes and provides data which are necessary in solving the problems. (PDF has 59 pages)

Juvenile fish assemblages collected on unconsolidated sediments of the southeast United States continental shelf

Patterns were investigated in juvenile fish use of unconsolidated sediments on the southeast United States continental shelf off Georgia. Juvenile fish and environmental data were sampled at ten stations along a 110-km cross-shelf transect, including four stations surrounding Gray’s Reef National Marine Sanctuary (Gray’s Reef NMFS). Cross-shelf stations were sampled approximately quarterly from spring 2000 to winter 2002. Additional stations were sampled on three transects inshore of Gray’s Reef NMS and four transects offshore of the Sanctuary during three cruises to investigate along-shelf patterns in the juvenile fish assemblages. Samples were collected in beam trawls, and 121 juvenile taxa, of which 33 were reef-associated species, were identified. Correspondence analysis on untransformed juvenile fish abundance indicated a cross-shelf gradient in assemblages, and the station groupings and assemblages varied seasonally. During the spring, fall, and winter, three cross-shelf regions were identified: inner-shelf, mid-shelf, and outer-shelf regions. In the summer, the shelf consisted of a single juvenile fish assemblage. Water depth was the primary environmental variable correlated with cross-shelf assemblages. However, salinity, density, and water column stratification also correlated with the distribution of assemblages during the spring, fall, and winter, and along with temperature likely influenced the distribution of juvenile fish. No along-shelf spatial patterns were found in the juvenile fish assemblages, but the along-shelf dimension sampled was small (~60 km). Our results revealed that a number of commercially and recreationally important species used unconsolidated sediments on the shelf off Georgia as juvenile habitat. We conclude that management efforts would be improved through a greater recognition of the importance of these habitats to fish production and the interconnectedness of multiple habitats in the southeast U.S. continental shelf ecosystem.

An assessment of chemical contaminants in the marine sediments of southwest Puerto Rico

This report summarizes the results of a characterization of chemical contaminants in the sediments in southwest Puerto Rico. The report is part of a project to integrate various analytical specialties to assess linkages between chemical contaminants and the condition of coral reefs. In this phase of the project, over 120 chemical contaminants were analyzed in sediments collected, including a number of organic (e.g., hydrocarbons), inorganic (e.g., metals), and biological (bacterial) compounds/analytes. The report also provides a preliminary analysis of the association between sediment contaminants and coral species richness. Overall, the levels of chemical contaminants in the study area between Guanica Bay and the town of La Parguera were fairly low. At most of the sites sampled, particularly adjacent to the town of La Parguera, concentrations of organic and inorganic contaminants were below the median values from NOAA’s National Status and Trends Program, which monitors the Nation’s coastal and estuarine waters for chemical contaminants. Elevated levels of a number of contaminant classes were seen at the two sites sampled within Guanica Bay. An initial analysis of modeled PAH (hydrocarbon) data and coral species richness (reef building species) indicated a strong negative correlation between the presence of PAHs in the sediments and coral species richness. Additional work is needed to assess possible reasons for this observed pattern. (PDF contains 126 pages).

Long-Term Monitoring of Ecological Conditions In Gray’s Reef National Marine Sanctuary: Comparison of soft-bottom benthic assemblages and contaminant levels in sediments and biota in Spring 2000 and 2005

As part of an ongoing program of benthic sampling and related assessments of sediment quality at Gray’s Reef National Marine Sanctuary (GRNMS) off the coast of Georgia, a survey of soft-bottom benthic habitats was conducted in spring 2005 to characterize condition of macroinfaunal assemblages and levels of chemical contaminants in sediments and biota relative to a baseline survey carried out in spring 2000. Distribution and abundance of macrobenthos were related foremost to sediment type (median particle size, % gravel), which in turn varied according to bottom-habitat mesoscale features (e.g., association with live bottom versus flat or rippled sand areas). Overall abundance and diversity of soft-bottom benthic communities were similar between the two years, though dominance patterns and relative abundances of component species were less repeatable. Seasonal summer pulses of a few taxa (e.g., the bivalve Ervilia sp. A) observed in 2000 were not observed in 2005. Concentrations of chemical contaminants in sediments and biota, though detectable in both years, were consistently at low, background levels and no exceedances of sediment probable bioeffect levels or FDA action levels for edible fish or shellfish were observed. Near-bottom dissolved oxygen levels and organic-matter content of sediments also have remained within normal ranges. Highly diverse benthic assemblages were found in both years, supporting the premise that GRNMS serves as an important reservoir of marine biodiversity. A total of 353 taxa (219 identified to species) were collected during the spring 2005 survey. Cumulatively, 588 taxa (371 identified to species) have been recorded in the sanctuary from surveys in 2000, 2001, 2002, and 2005. Species Accumulation Curves indicate that the theoretical maximum should be in excess of 600 species. Results of this study will be of value in advancing strategic science and management goals for GRNMS, including characterization and long-term monitoring of sanctuary resources and processes, as well as supporting evolving interests in ecosystem-based management of the surrounding South Atlantic Bight (SAB) ecosystem. (PDF contains 46 pages)

Soft-bottom benthic assemblages and levels of contaminants in sediments and biota at Gray's Reef National Marine Sanctuary and nearby shelf waters off the coast of Georgia (2000 and 2001)

A series of studies was initiated to assess the condition of benthic macroinfauna and chemical contaminant levels in sediments and biota of the Gray’s Reef National Marine Sanctuary (GRNMS) and nearby shelf waters off the coast of Georgia. Four key objectives of the research are (1) to document existing environmental conditions within the sanctuary in order to provide a quantitative benchmark for tracking any future changes due to either natural or human disturbances; (2) to examine broader cross-shelf spatial patterns in benthic fauna and sediment contaminant concentrations and to identify potential controlling factors associated with the observed patterns; (3) to assess any between-year temporal variability in benthic fauna; and (4) to evaluate the importance of benthic fauna as prey for higher trophic levels. Such questions are being addressed to help fulfill long-term science and management goals of the GRNMS. However, it is anticipated that the information will be of additional value in broadening our understanding of the surrounding South Atlantic Bight (SAB) ecosystem and in bringing the knowledge to bear on related resourcemanagement issues of the region. We have begun to address the first three of these objectives with data from samples collected in spring 2000 at stations within GRNMS, and in spring 2001 at stations within the sanctuary and along three cross-shelf transects extending from the mouths of Sapelo, Doboy, and Altamaha Sounds out to sanctuary depths (about 17-20 m). This report provides a description of baseline conditions within the sanctuary, based on results of the spring 2000 survey (Section II), and uses data from both 2000 and 2001 to examine overall spatial and temporal patterns in biological and chemical variables within the sanctuary and surrounding inner-shelf environment (Section III). (PDF contains 65 pages)