The carbonate radical anion (CO3•-, CR) is an important reactive oxygen species produced in vivo by one-electron oxidation of CO2 or bicarbonate, constituents of the major physiological buffer. It was demonstrated for the first time by using an HPLC-based analysis of low-molecular products of DNA damage that CRs react with DNA 2΄-deoxyribose by the hydrogen abstraction mechanism. CRs exhibit a ~ 800-fold preference for one-electron oxidation of guanine over hydrogen abstraction from DNA sugar, in sharp contrast with •OH. CRs also have, as compared to •OH, an increased preference for the H1΄ abstraction, which is the most thermodynamically favorable due to the highest stability of the respective deoxyribosyl radical but kinetically the slowest due to low solvent accessibility, by the expense of the decreased preference for the H5΄ abstraction. All these findings are in agreement with the characteristics of CR as a potent oxidant and selective hydrogen abstractor.

Increasing concentrations of atmospheric CO2 are in dynamic equilibrium with the oceans. The absorption of CO2 by seawater causes a decrease in seawater pH and calcite saturation state (SS). This process, termed ocean acidification, exerts deleterious effects on marine calcifiers. Studies of symbiont-bearing large benthic foraminifera (LBF) have reported a generally unfavorable response to increased concentrations of carbon dioxide ([CO2]). Experiments and analyses were undertaken to examine the effect of increased [CO2] on the growth rate, ultrastructure, stable isotopes of carbon and oxygen, as well as Mg/Ca of the high-Mg miliolid Archaias angulatus and the low-Mg rotalid Amphistegina gibbosa. A CO2-injection culture study was performed at pH 8.0, 7.8 and 7.6, corresponding to CO2 concentrations of approximately 400 ppm, 800 ppm, and 1,300 ppm. After 2, 4, or 6 weeks of treatment, bags containing groups of approximately 20 previously-imaged live specimens were removed and prepared for the aforementioned analyses. Archaias angulatus responded to increased [CO2] by reducing test growth rate at 1,300 ppm CO2 (pH 7.6) by 50% (p < 0.01, r2 = 36%), increasing its pore area (F(2,3477) = 103.37, p West Florida shelf LBF carbonate production attributed to LBF was estimated by combining interpolations of SS calcite at three treatment levels, corresponding to pH 8.1 (400 ppm CO2), pH 7.8 (800 ppm CO2), and pH 7.6 (1,300 ppm CO2), with a map of the carbonate fraction of seafloor sediment. Growth rates for 10 species were estimated in a meta-analysis of culture studies; these rates were used to model the response of miliolids and rotalids to increased [CO2]. In the model, rotalids responded to higher CO2 concentrations by reducing their average adult size by 20% at 800 ppm CO2 and 40% at 1,300 ppm CO2. Miliolids responded by reducing their average adult size by 40% at 800 ppm CO2 and 75% at 1,300 ppm CO2. Modeled LBF carbonate production for the west Florida shelf is 7 Mt at 400 ppm, 4.8 Mt at 800 ppm, and 2.5 Mt at 1,300 ppm. In a high CO2 world, low-Mg rotalids exhibit modest reductions in test growth rates and carbonate production, whereas high-Mg miliolids exhibit major reductions in test growth rates and carbonate production.

The Coral Sea has been the host to a variety of large carbonate platforms over the geologic past and presently hosts the world's largest system of coral reefs, the Great Barrier Reef, stretching more then 2,300 km along Australia's northeast coast. The Marion Plateau, which today is the site of 400 m deep hemipelagic sediment drifts, once supported two large carbonate platforms that were precursors to reef growth on the central and southern Great Barrier Reef. Previous work examining the growth phases, drownings and rejuvenation of these platforms is extensive. The purpose of this research is to examine the factors controlling the earliest sedimentation on the margin and how it influenced early development of the carbonate platforms. One hundred and eighty-three samples were taken from the base of Hole 1195 B, that was drilled during the Ocean Drilling Program's Leg 194. Analyses were performed using x-ray diffraction on the bulk powder and decalcified less than 2um size fraction smear slides. Four distinct sedimentary facies were defined on the basis of mineralogy and constituent grains. The initial marine transgression of the Marion Plateau was not a straightforward one where a shallow-water margin gradually transitioned into a deep-water margin. Instead, sediments record a complex history of unconformities, hardgrounds, and discrete sedimentary units. The initial flooding was complex as a result of its initially shallow depth at a time characterized by several glacio-eustatic sea-level changes. The data indicate that eustasy has been the strongest control on sediment deposition and clay mineral patterns on the Plateau. Falling sea level resulted in periods of increased detrital input and limited soil formation. Also, a decreasing kaolinite trend in the early Miocene, during a rising sea level, indicates that clays forming on land as a result of climate were not transported out onto the plateau.

The Late Pennsylvanian was a time of frequent, rapid glacioeustatic sea-level changes. These changes were recorded in the Wolfcamp D Formation of the Midland Basin as a series of cyclothems similar to those studied in the Midcontinent region (e.g., Algeo and Heckel, 2008). This study focuses on identifying the mechanisms and controls on carbonate deposition and diagenesis through the Upper Pennsylvanian Wolfcamp D Formation and evaluating the potential for these layers to be stratigraphically significant. A stepwise progression of diagenetic processes was identified through the use of δ13Ccarb and δ18Ocarb, bulk geochemical and petrographic analysis, and scanning electron microscopy. Carbonate deposition and early-burial diagenesis appears to be strongly influenced by frequent changes in sea-level and benthic redox conditions. The transition to deep-burial diagenesis was controlled by the thermal gradient in the basin and the extent of diagenesis by the amount of clays and organic matter in the surrounding mudrocks. Further diagenesis was induced through interactions with a brine following clay diagenesis. The presence of multiple phases of diagenesis in this system further highlights the need for several lines of inquiry when evaluating the post-depositional evolution of carbonates in a mud-rich setting.

The effect of Mg++ ion on the solubility of calcium carbonate was determined using P. K. Weyls "carbonate saturometer." The amount of calcium carbonate precipitated or dissolved was measured for five series of waters when equilibrated with solid carbonate. It was found that the effect of Mg++ ion on solubility depend upon the nature of the solid phase: surface area, coprecipitated Mg++, minerology, etc. Pure low area calcite showed an increase in solubility which could be explained by ion-pair formation, while its other carbonates departed from this behavior.

The Hillsborough River flows southwesterly through Pasco and Hillsborough counties in west central Florida. From its source at the Green Swamp to its mouth in Hillsborough Bay, the river is joined by many tributaries and man-made inputs. Spatial and temporal variations in the river's major ion and CO2 system chemistry were examined in a two-year study between 1999 and 2001. At thirteen sampling stations along approximately 54 miles of the river, water samples were collected in surroundings that ranged from pristine to urban. Samples were collected monthly for the first year and periodically thereafter. Concentrations of major ions were lowest in the river's headwaters, showed only minor spatial variations in mid-river, and sharply increased in tidally influenced waters below a dam on the lower river. A major tributary, Blackwater Creek, exerts a strong influence on the river's phosphate concentrations, and Crystal Springs, upstream of Blackwater Creek, exerts a strong influence on nitrate concentrations in the river. Downstream of Crystal springs, NO3- concentrations decreased steadily to levels that are more than an order of magnitude lower than levels in the upper river. Temporal ion concentration variations can be quite large. Low major ion concentrations were observed in the rainy season (June-September), while phosphate concentrations increased dramatically during extremely wet conditions. Seasonal variations were also observed in the river's CO2 system. Riverwater pH decreased during periods of high precipitation along with CaCO3 saturation state. CaCO3 supersaturation was observed during the exceptionally dry periods of the study, and undersaturation was observed during periods of high rainfall.Overall, the chemistry of the Hillsborough River is greatly influenced by temporal and spatial variations in the river's tributaries, groundwater sources, and anthropogenic inputs.

Historically, Archaias angulatus has been a major contributor to foraminiferal assemblages and sediments in coral-reef environments throughout the Caribbean and tropical Atlantic. A variety of anomalous features were observed in the tests of A. angulatus individuals collected live from the Florida reef tract in 2004 and 2005. Six types of anomalies were documented using scanning electron microscopy: microborings, microbial biofilm, pitted surfaces, dissolution, calcification abnormalities, and growth abnormalities. Calcification abnormalities included mineralogical projections, lacy crusts, and repair marks. These abnormalities were found among both juvenile and adult A. angulatus, and similar features were also found among Cyclorbiculina compressa and Laevipeneroplis proteus specimens collected live in the same samples. In 2006, a comprehensive study was undertaken to see if the occurrence and types of morphological abnormalities have changed in A. angulatus from the Florida Keys over the past 2.5 decades. Archived samples of A. angulatus collected in 1982-83 from John Pennekamp Coral Reef State Park were compared to recent samples. Seven different types of morphological abnormalities and 5 different surface texture anomalies were documented. Eighty-six combinations of abnormalities and surface textures were observed. Physical abnormalities included profoundly deformed, curled, asymmetrical, and uncoiled tests, irregular suture lines, surface "blips," and breakage and repair. Surface texture anomalies included surface pits, dissolution, microborings, microbial biofilm, and epibiont growth. Epibiont growth included bryzoans, cyanobacteria and foraminifers. The archived samples were not obviously more pristine than the recent samples indicating stress was well underway in the early 1980s. Test strength was compromised in deformed specimens. Crushing strength of abnormal individuals was much more variable compared to individuals with irregular sutures and normal specimens. Deformed individuals also exhibited abnormal test wall structure including dissolution and infilling. Mg/Ca ratios for normal and deformed specimens were within normal parameters (12-15 µmol/mol). Implications of these observations are at least twofold. First, in studies of fossil assemblages, damage to tests and changes in test-surface textures should not be assumed to have occurred postmortem, and may provide evidence of environmental stressors acting upon living populations. In addition, we speculate that test dissolution in larger miliolid foraminifers when alive can indicate declining carbonate saturation in seawater, which can result locally from salinity changes or increasing benthic respiration rates, as well as globally from rising concentration of atmospheric CO2.

This work provides improved procedures for spectrophotometric carbon system measurements. Indicator dyes used for routine spectrophotometric pH measurements in seawater suffer from impurity issues, which introduce vendor-specific systematic errors in pH determinations. The magnitude of these errors for several vendors was investigated for meta Cresol Purple (mCP) and Cresol Red (CR). Flash chromatography procedures were developed to obtain purified mCP and CR on a bulk scale in order to supply the oceanographic research community with the indicators. Easy access to the purified indicators ensures global intercomparability of spectrophotometric pH determinations. Internal consistency of marine inorganic carbon system measurements was studied using datasets obtained on two large coastal ocean acidification research cruises. In both cases, purified mCP was used to obtain the pH measurements, thereby improving accuracy relative to previous studies in which measurements were obtained with unrefined mCP. Based on this internal consistency study, recommendations are made for selecting the parameter pairs used for saturation state calculations. Direct spectrophotometric methods for measuring carbonate ion concentrations in seawater were improved by (a) using a higher concentration of lead as the carbonate indicator and (b) altering the carbonate computational algorithm based on high quality field data. Measurements of DIC and pH (using purified mCP) were used to calculate carbonate ion concentrations for comparison with spectrophotometrically measured carbonate ion concentrations (i.e., via spectrophotometric measurements of Pb(II) spectra in the ultraviolet). Minor changes in the computational algorithm substantially improved agreement between measured and calculated carbonate ion concentrations.

Reverse Osmosis (RO) is widely accepted as an alternative method to produce freshwater from different feed water sources. This technology competitively substitutes the thermal processes in the near future because of several advantages particularly in energy saving. The success of RO operation will, however, depends largely on the overall membrane performance. Deposit or build-up of solute is one of the main reasons for membrane operation failure. Build-up of solute or deposit which is known as fouling and scaling will decrease the permeate flux and increase the energy consumption in particular after prolonged operation of RO. The thesis presents the experimental results obtained in a small-scale RO system. The aim of this study is to investigate the effect of sodium chloride and calcium carbonate on the membrane performance and subsequent build-up of solute on the membrane surface. The experiments were carried out in a small-scale of RO (2 m3/day capacity) with spiral wound membrane using simulated feed water, secondary effluent, and groundwater samples. The parameters chosen for the experiments are applied pressure (1250-4750 kPa), and concentration of sodium chloride (l00-5000 mg/L) and calcium carbonate (50-100 mg/L). / The results from feedwater runs indicated that initial sodium chloride and calcium carbonate in feed water and applied pressure affects the overall membrane performance. However, there is no significant effect on membrane performance for sodium chloride with concentration below 1200 mg/L and applied pressure lower than 2250 kPa. Applied pressure appears to have an impact on build-up of sodium and calcium on the membrane surface for pressures greater than 2750 kPa. For typical small-scale RO system used in this experiment, build-up of calcium will slightly decrease with given pressure caused by the characteristic of membrane that easily removes the divalent ions. The osmotic pressure of solution also strongly affects the permeate flow rate in particular for relatively higher sodium concentration (> 2500 mg/L). As a consequence of higher osmotic pressure, zero permeate flux is achieved when sodium chloride concentration was greater than 5000 mg/L and applied pressure lower than 1750 kPa. Results also indicated that fouling might pose a potential problem in small-scale RO operation. In order to investigate the membrane performance, experiments with secondary effluent samples were also performed. Results indicated that water recovery percentages and permeate flux also linearly increase with applied pressure. However, effectiveness of membrane decreases less than 98% otherwise build-up of solute tends to increase. It is suggested that lower values of the water recovery percentage (WRP) and permeate flux (Jw) are caused by the characteristic of secondary effluent that have high-suspended solids, organic carbon, and minerals. Further, the membrane performance also examined with ground water as feed water sample. / Results showed that both water recovery percentage and permeate flux linearly increased with operating pressure. However, intensive pretreatment are required as a result of higher concentration of humic acid and iron in raw feed. Percentages of ion rejection for sodium and calcium are greater than 98 and 99% respectively. The high ion rejections are mainly due to the characteristics of groundwater with low TDS and EC. Sodium and calcium build-up in a small-scale RO system considered appears to be affected by the applied pressure. Build-up of solute in small-scale of RO system has been predicted using the empirical model proposed in this work. Two ions namely sodium and calcium in feed water considered as predominant ions responsible for fouling and scaling on the membrane surface. Four main parameters namely, applied pressure (P), permeate flux (Jw), membrane resistance (Rm), and feed concentration (Cf) are considered which strongly affect the overall membrane performance. The empirical correlations derived from experimental observation among these parameters can be expressed as follows: In Md NaCI = O. 77 In P + 0.67 In Jw + 0.19 In Rm + 0.171n Cf In Md CaCO3= 0.96 In P + 0.75 In Jw + 0.2 In Rm - 0.07 In Cf / The empirical models proposed in this thesis may be useful for predicting the buildup of solute on the membrane surfaces. In the present work, an attempt has been made to estimate the energy consumption and unit cost for desalting of different feed water samples in a small-scale RO system. In RO plants, unit cost of water production from feed water is primarily governed by the energy required for pumping raw water. Estimates of specific energy consumption (SEC) for desalting of sodium chloride, combined sodium and calcium carbonate solutions were found to be in the range of 0.79 - 3.21 and 0.81 - 3.22 kwh/m3 respectively. For groundwater and secondary effluent, they are estimated to 0.63 - 1.71 and 0.79 - 2.02 kWh/m3 respectively. Moreover, energy consumption for different feed water samples was used to estimate the unit cost for water production. Estimation of unit costs for combined sodium chloride and calcium carbonate solution, groundwater, and secondary effluent runs are $2.06 - 3.22, $1.98 - 2.57 and $1.56- 2.66 respectively. In this work, unit cost is still higher due to greater energy consumption .by the pumping system which is required in a small-scale RO operation. Based on the experimental results, it appears that the characteristics of feed water samples affect the membrane performance and their effects must be taken into account in the design of RO units so as to reduce the unit cost for water production. / The findings from the present experimental and modelling work are of practical significance in not only providing the knowledge base in the area of desalination but also paves the way for developing tools for the prediction of build-up of solutes on membrane surface in full scale reverse osmosis operations.

Temperate mixed carbonate-siliciclastic sediments and authigenic minerals are the current surficial deposits at shelf and slope depths (30-1015 m water depth) on the north Kaipara continental margin (NKCM) in northern New Zealand. This is the first detailed study of these NKCM deposits which are described and mapped from the analysis of 54 surficial sediment samples collected along seven shorenormal transects and from three short piston cores. Five surficial sediment facies are defined from the textural and compositional characteristics of this sediment involving relict, modern or mixed relict-modern components. Facies 1 (siliciclastic sand) forms a modern sand prism that extends out to outer shelf depths and contains three subfacies. Subfacies 1a (quartzofeldspathic sand) is an extensive North Island volcanic and basement rock derived sand deposit that occurs at less than 100-200 m water depth across the entire NKCM. Subfacies 1b (heavy mineral sand) occurs at less than 50 m water depth along only two transects and consists of predominantly local basaltic to basaltic andesite derived heavy mineral rich (gt30%) deposits. Subfacies 1c (mica rich sand) occurs at one sample site at 300 m water depth and contains 20-30% mica grains, probably sourced from South Island schists and granites. Facies 2 (glauconitic sand) comprises medium to fine sand with over 30% and up to 95% authigenic glauconite grains occurring in areas of low sedimentation on the outer shelf and upper slope (150-400 m water depth) in central NKCM. Facies 3 (mixed bryozoan-siliciclastic sand) consists of greater than 40% bryozoan skeletal material and occurs only in the northern half of the NKCM. Facies 4 (pelletal mud) occurs on the mid shelf (100-150 m water depth) in northern NKCM and comprises muddy sediment dominated by greater than c. 30% mixed carbonatesiliciclastic pellets. Facies 5 (foraminiferal mud and sand) contains at least 30% foraminifera tests and comprises two subfacies. Subfacies 5a consists of at least 50% mud sized sediment and occurs at gt400 m water depth in southern NKCM while subfacies 5b comprises gt70% sand sized sediment and occurs at mid to outer shelf and slope depths in the northern NKCM. vi A number of environmental controls affect the composition and distribution of NKCM sediments and these include: (1) variable sediment inputs to the NKCM dominated by inshore bedload sources from the south; (2) northerly directed nearshore littoral and combined storm-current sediment transport on the beach and shelf, respectively; (3) offshore suspended sediment bypassing allowing deposition of authigenic minerals and skeletal grains; (4) exchange between the beach and shelf producing similar compositions and grain sizes at less than 150 m water depth; and (5) the episodic rise of sea level since the Last Glaciation maximum approximately 20 000 years ago which has resulted in much sediment being left stranded at greater depths than would otherwise be anticipated. Sedimentation models developed from other wave-dominated shelves generally do not appear to apply to the NKCM sediments due to their overall relative coarseness and their mosaic textural characteristics. In particular, the NKCM sediments do not show the expected fining offshore trends of most wavedominated shelf models. Consequently, sandy sediments (both siliciclastic and authigenic) are most typical with mud becoming a dominant component in southern NKCM sediments only at greater than 400 m water depth, over 350 m deeper than most models suggest, a situation accentuated by the very low mud sediment supply to the NKCM from the bordering Northland landmass.