Understanding the importance of sediments to water ouality in coastal shallow lagoons

The undesirable enrichment of water by nutrients may be a problem, especially in areas with restricted exchange with the sea. The tidal regime flushes the system and contributes for the removal of phytoplankton, favouring phytobenthos as the target of enhanced nutrients. Water samples were collected during the years of 2006 and 2007-08 for nutrients, chlorophyll a and dissolved oxygen. Sediment sample s were also collected for pore water nutrients and benthic chlorophyll a. From comparison with previous work, a decrease in the nitrogen concentration in the water column can be pointed out, which may indicate an improvement of the water quality. Pore water DAIN represents approximately 75% of the total DAIN of the whole lagoon. Benthic chlorophyll a concentrations were much larger than in the water column, representing around 99% of the total chlorophyll existent in the lagoon. Benthic microalgae play a relevant role in this system and therefore standard monitoring programs of the WFD, which do not consider this component, may fail to track nutrient-driven changes in primary producers. Dissolved oxygen concentration could be near critical levels during the summer (early in the morning), especially in the inner channels.

Effects of fluvial and marine processes on nearshore suspended sediment concentrations off the Elwha River

Senior thesis written for Oceanography 444

Geological structure and acoustic properties of sediments in Effingham Inlet

Thesis written for Oceanography 445

Microbial community composition and mercury cycling in sediments of tagus estuary

Tese de doutoramento, Farmácia (Toxicologia), Universidade de Lisboa, Faculdade de Farmácia, 2016

Depositional characteristics and trace metal abundance of sediments in an anoxic basin

Senior thesis written for Oceanography 445

Environmental impact assessment: looking at sediments in Nootka Sound for traces of pulp mill effluent

Senior thesis written for Oceanography 445

Analysis of PCBs in soils and sediments by microwave-assisted extraction, headspace-SPME and high resolution gas chromatography with ion-trap tandem mass spectrometry

A procedure for the determination of seven indicator PCBs in soils and sediments using microwave-assisted extraction (MAE) and headspace solid-phase microextraction (HS-SPME) prior to GC-MS/MS is described. Optimization of the HS-SPME was carried out for the most important parameters such as extraction time, sample volume and temperature. The adopted methodology has reduced consumption of organic solvents and analysis runtime. Under the optimized conditions, the method detection limit ranged from 0.6 to 1 ng/g when 5 g of sample was extracted, the precision on real samples ranged from 4 to 21% and the recovery from 69 to 104%. The proposed method, which included the analysis of a certified reference material in its validation procedure, can be extended to several other PCBs and used in the monitoring of soil or sediments for the presence of PCBs.

Calidad ambiental de las bahías Samanco y Tortuga, Áncash, Perú: 2010-2011

Se efectuaron estudios en junio y octubre-noviembre 2010 y en julio y noviembre-diciembre 2011. Se hicieron muestreos por mar para determinar parámetros físicos, químicos y microbiológicos, empleando protocolos y metodologías nacionales e internacionales (USEPA, APHA). En Samanco el oxígeno disuelto varió entre 7,00 y 8,20 mg/L; en Tortuga de 6,46 a 7,42 mg/L. Los sólidos suspendidos totales en Samanco fueron 37,00 mg/L y en Tortuga 33,28 mg/L; aceites y grasa fueron >1,00 mg/L superando los Estándares Nacionales de Calidad Ambiental (ECA) categoría 4. Los valores de demanda bioquímica de oxígeno (DBO5) fueron <10,00 mg/L. Las concentraciones de cadmio (4,21 μg/g) y plomo (30,24 μg/g) en sedimento no sobrepasaron los valores de Protección Costera y Restauración (USA). Se detectó que la bahía Samanco presenta mayor grado de impacto ambiental que la bahía Tortuga.

The surficial geology, sedimentology and geochemistry of the late glacial sediments and Paleozoic bedrock in the Campbellford area, Ontario, with special reference to the Dummer Complex /

The Dummer Complex extends 180 km along the Precambrian - Paleozoic contact from Tamworth to Lake Simcoe. It is composed of coarse, angular Paleozoic clasts in discontinuous, pitted, hummocky deposits. Deposits are usually separated by bare or boulder strewn bedrock, but have been found in the southern drumlinized till sheet. Dummer Complex deposits show rough alignment with ice-flow. Eskers cross-cut many of the deposits. Dummer sediment subfacies are defined on the basis of dominant coarse grain size and lithology, which relate directly to the underlying Paleozoic formation. Three subglacial tills are identified based on the degree of comminution and distance of transport; the immature facies of the Dummer Complex; the mature facies of the drumlinized till sheet and; the submature facies which is transitional. Carbonate geochemistry was used for till-bedrock correlation in various grain sizes. Of the 3 Paleozoic formations underlying the Dummer Complex, the Gull River Fm. is geochemically distinctive from the Bobcaygeon and Verulam Formations using Ca, Mg, Sr, Cu, Mn, Fe and Na. The Bobcaygeon Fm. and Verulam Fm. can be differentiated using Ca and the Sr/Ca ratio. The immature facies from 1.0 phi and finer is dominated by the non-carbonate, long distance transported component which decreases slightly downice. The submature till facies contains more long distance material than the immature facies. Sr and Mn can be used to correlate the Gull River immature till facies to the underlying bedrock the other subfacies could not be distinguished from each other or their respective source formation. This method proved to be ineffective for sediments with greater than 35% non-carbonate component, due to leaching of elements by the dissolving acid.The Dummer Complex is produced subglacially , as the compressional ice encounters the permeable Paleozoic carbonates. The increased shear strength of the ice and pore pressures in the carbonates results in the basal ice zones becoming debris ladden. Cleaner ice overrides the basal debris . laden dead ice which then acts as the glacier bed. During retreat, the Simcoe lobe stagnates as flow is cut-off by the Algonquin Highlands.

Palynology of late-glacial and postglacial sediments in Georgian Bay, Ontario, Canada, as related to the Great Lakes history /

This investigation comprises three parts: (1) the source, mechanism of transport, and distribution of pollen, spores and other palynomorphs in Georgian Bay bottom sediments and a comparison of these data with the contemporary vegetation, (2) the relative significance of fluvial transportation of pollen and spores, and (3) the late- and postglacial history of vegetational and climatic changes in the Georgicin Bay region. Modem pollen and spore assemblages in Georgian Bay do reflect the surrovinding vegetation when preservation and pollen production by the different species are considered and accounted for. Relative pollen percentage and concentration isopoll patterns indicate that rivers contribute large quantities of pollen and spores to Georgian Bay. This is further substantiated by large amounts of pollen and spores which were caught in traps in the Moon, Muskoka, and Nottawasaga Rivers which flow into Georgian Bay. The majority of pollen and spores caught in these traps were washed into the rivers by surface water runoff and so reflect the vegetation of the watershed in a regional sense. In a 12.9 metre long sediment core from northeastern Georgian Bay the relative percentage and absolute pollen concentrations allow correlation of Georgian Bay Lake phases with climatic and forest history. Four distinct pollen zones are distinguished: zone GB IV which is the oldest, reflects the succession from open spruce woodland to boreal forest; zone GB III represents a period of pine-mixed hardwoods forests from about 10,000 to 7,500 years ago. A pine-maplehemlock association dominated in zone GB II, although during the culmination of postglacial warming about 4,000 to 5,000 years ago the Georgian Bay forests had a more deciduous character. Zone GB I clearly shows European man's disturbance of the forest by logging activities.

Pollen and grain size records in abyssal sediments of the northwest Pacific Ocean as proxies of Plio-Pleistocene climate change /

A distinctive period of global change occurred during the PUocene between the warm Miocene and subsequent Quaternary cooling. Samples from Ocean Drilling Project Site 11 79 (-5586 mbsl, 41°4'N, 159°57'E), Site 881 (-5765 mbsl, 47°6.133'N, 161°29.490'E) and Site 882 (-3255 mbsl, 50°22'N, 167°36'E) were studied to determine the magnitude and composition ofterrigenous flux to the western mid-latitude North Pacific and its relation to climate change in East Asia since the mid-Pliocene. Dust-sized particles (including pollen), sourced from the arid regions and loess plateaus in East Asia are entrained by prevailing westerly winds and transported to the midlatitude northwest North Pacific Ocean. This is recorded by peaks in the total concentration of pollen and spores, as well as the mean grain size of allochthonous and autochthonous silicate material in abyssal marine sediments. Aridification of the Asian interior due to the phased uplift of the Himalayan-Tibetan Plateau created the modem East Asian Monsoon system dominated by a strengthening of the winter monsoon. The winter monsoon is further enhanced during glacials due to the expansion of desert and steppe environments at the expense ofwoodlands and forests recorded by the composition of palynological assemblages. The late Pliocene-Pleistocene glacials at ODP Sites 1 179, 881, and 882 are characterized by increases in grain size, magnetic susceptibility, pollen and spore concentrations around 3.5-3.3, 2.6-2.4, 1.7-1.6, and 0.9-0.7 Ma (ages based on magnetostratigraphic and biostratigraphic datums). The peaks during these times are relatively rich in pollen taxa derived primarily from steppe and boreal vegetation zones, recording cool, dry climates. The overall size increase of sediment and abundance of terrestrial palynomorphs record enhanced wind strength. The increase in magnitude of pollen and spore concentrations as well as grain size record global cooling and Northern Hemisphere glaciation. The peaks in grain size as well as pollen and spore abundance in marine sediments correlate with the mean grain size of loess in East Asia, consistent with the deflation of unarmoured surfaces during glacials. The transport of limiting nutrients to marine environments enhanced sea surface productivity and increased the rate of sediment accumulation.

An investigation of geological and geochemical characteristics of late-Quaternay sediments in the Georgian Bay Region, Southern Ontario

Core samples of postglacial sediments and sediment surface samples from Shepherd Lake on the Bruce Peninsula, Harts Lake on the Canadian Shield, and two cores from Georgian Bay (core P-l in the western deep part and core P-7 in the eastern shallow part) have been analyzed for pH, grain size distribution, water content, bulk density, loss on ignition at 4500C and 11000 C, major oxides (Si02 ,A1203,!FeO,MgO,CaO, Na20,K20,Ti02 ,MnO and P205) and trace elements (Ba,Zr,Sr,y,S, Zn,Cu,Ni,Ce and Rb). The sediment in Georgian Bay are generally fine grained (fine silt to very fine silty clay) and the grain size decreases from the Canadian Shield (core p-7) towards the Bruce Peninsula (core P-l) along the assumed direction of sediment transport. This trend coincides with a decrease in sorting coefficient and an increase in roundness. Other physical characteristics, such as water content, bulk density and loss on ignition are positively correlated with the composition of sediments and their compaction, as well as with the energy of the depositional environment. Analyses of sediment surface samples from Shepherd Lake and Harts Lake indicate the influence of bedrock and surficial deposits in the watershed on pH condition that is also influenced by the organic matter content and probably I ! I man's activities. Organic matter content increases significantly in the surface sediment in these small lakes as a result of either natural eutrophication or anthropogenic organic loading. The extremely high organic matter content in Shepherd Lake sediment indicates rapid natural eutrophication in this closed basin and high biological productivity during postglacial time, probably due to high nutrient levels and shallow depth. The chemical composition of the Canadian Shield bedrock is positively correlated with the chemical characteristics of predominantly inorganic lake sediments that were derived from the Shield rocks by glacial abrasion and by postglacial weathering and erosion of both bedrock and surficial deposits. High correlation coefficients were found between organic matter in lake sediments and major oxides (Si02,AI203,.~FeO, MgO,CaO,K20 and MnO) , as well as some trace elements (Ba,Y, S,Zn,Cu,Ni and Rb). The chemical composition of sediments in Harts Lake and core P-7 in Georgian Bay on the Canadian Shield differs from the chemistry of sediments in Shepherd Lake and core P-l in Georgian Bay on the Bruce Peninsula. The difference between cores P-l and P-7 is indicated by values of Si02 , AI203 ,:LFeo,Mgo,CaO,Ba,Zr,Sr,y and S, and also by the organic matter content. This study indicates that the processes of sediment transport, depositional environment, weathering of the rocks and surficial deposits in the watershed, as well as chemical composition of source rocks all affect the chemical characteristics of lake sediments. The stratigraphic changes and variations in lake sediment chemistry with regard to major oxides, trace elements, and organic matter content are probably related to the history of glacial and postglacial lake stages of the Georgian Bay Region and, therefore, the geochemical data can make a useful contribution to a better understanding of the Late-Quaternary history of the Great Lakes.

Environmental assessment of Lake Gibson sediments, water quality, and soils of the Niagara Region

In light of the fact that literature on toxicity of heavy metals in non-acidified freshwater systems is sparse, this project was initiated to conduct an environmental assessment of Lake Gibson. Chemistry of soils from adjacent areas and vineyards in the region provide a comparative background database. Water quality determinations were used to identify and highlight areas of environmental concern within the Lake Gibson watershed. A Shelby Corer was used to obtain 66 sediment cores from Lake Gibson. These were sectioned according to lithology and color to yield 298 samples. A suite of 122 soil samples was collected in the region and vicinity of Lake Gibson. All were tested for metals and some for Total Petroleum Hydrocarbons (TPH). Evaluation of the results leads to the following conclusions: 1. Metal concentrations ofAI, Cd, Cu, Cr, Pb, Ni, Fe and Zn in soils from the Niagara Region are well below background limits set by the Ministry of the Environment and Energy (MOEE) for provincial soils. 2. There is a spatial and depth difference for some of the metals within the various soils. The Cr, Ni and Pb contents of soils vary throughout the region (psediments from Lake Gibson fall below the LEL (Lower Effect Level) guideline specified by the MOEE for aquatic ecosystems. 4. All other metal contents exceed the LEL, and in some instances they also exceed the SEL (Severe Effect Level) guideline. In this instance acute toxicity testing of 11 the sediments is required to assess impact on the aquatic biota. 5. Specifically, effluents and discharges from outfalls, roadways, railways and industrial activities are all degrading the local ecosystem. 6. Mineral oil and greases are a major environmental concern in the sediments of Lake Gibson. Ofthe 240 samples tested for TPH, 200 samples exceed the MOEE Open Water Disposal Guideline of 1,500 mg/kg. 7. Four areas within Lake Gibson are especially degraded with respect to TPH. One area is just downstream from the Old WeIland Canal divergence point and waterfall. Other areas of concern are located just south of Beaverdams Road and just west ofthe Ontario Hydro control pipes; south ofthe Village ofBeaverdams. The fourth area of environmental concern and TPH impact is located between Highway 406 and Merrittville Highway.

Sedimentology and micromorphology of drumlin sediments at Chimney Bluffs State Park, New York, United States of America

The drumlin sediments at Chimney Bluffs, New York appear to represent a block-inmatrix style glacial melange. This melange comprises sand stringers, lenses and intraclasts juxtaposed in an apparently massive diamicton. Thin section examination of these glacigenic deposits has revealed microstructures indicative of autokinetic subglacial defonnation which are consistent with a deformable bed origin for the diamicton. These features include banding and. necking of matrix grains, oriented plasma fabrics and the formation of pressure shadows at the long axis ends of elongate clasts. Preservation of primary stratification within the sand intraclasts appears to suggest that these features were pre-existing up-ice deposits that were frozen, entrained, then deposited as part of a defonning till layer beneath an advancing ice sheet. Multi-directional micro-shearing within the sand blocks is thought to reflect the frozen nature of the sand units in such a high strain environment. It is also contended that dewatering of the sediment pile leading to the eventual immobilisation of the defonning till layer was responsible for opening sub-horizontal fissures within the diamicton. These features were subsequently infilled with mass flow poorly sorted sands and silts which were subjected to ductile defonnation during the waning stages of an actively deforming till layer. Microstructures indicative of the dewatering processes in the sand units include patches of fine-grained particles within a coarser-grained matrix and the presence of concentrated zones of translocated clays. However, these units were probably confined within an impermeable diamicton casing that prevented massive pore water influxes from the deforming till layer~ Hence, these microstructures probably reflect localised dewatering of the sand intraclasts. A layered subglacial shear zone model is proposed for the various features exhibited by the drumlin sediments. The complexity of these structures is explained in terms of ii superposing deformation styles in response to changing pore water pressures. Constructional glaciotectonics, as implied by the occurrence of sub-horizontal fissuring, is suggested as the mechanism for the stacking of the sand intraclast units within the diamicton. The usefulness of micromorphology in complimenting the traditional sedimentology of glacigenic deposits is emphasised by the current study. An otherwise massive diamicton was shown to contain microstructures indicative of the very high strain rates expected in a complexly deforming till layer. . It is quite obvious from this investigation that the classification of diamictons needs to be re-examined for evidence of microstructures that could lead to the re-interpretation of diamicton forming processes. RESUME Le pacquet de sediments drumlinaire de Chimney Bluffs, New York, represent un "bloc-en-matrice" genre de melange glaciale. Des structures microscopique comprennent l'evidence pour la defonnation intrinseque attribuee a l'origine lit non resistant du drumlin. PreselVation des structures primaires au coeur des blocs arenaces suggere que ceux sont des depots preexistant qui furent geles, entraines et par la suite sedimentes au milieu d'une couche de debris sous-glaciaires en voie de deformation. Des failles microscopiques a l'interieur des blocs arenaces appuient aussi l'idee d'un bloc cohesif (c'est-a-dire gele) au centre d'un till non resistant. Des implications significatives s'emergent de cette etude pour les conditions sous-glaciaire et les processus de la formation des drumlin.