Coring and augering

This chapter introduces the principles of coring, including the objectives for taking a good core and the major factors that should be considered to ensure the collection of non disturbed, representative core samples. The chapter also provides an overview of the design, function, and operation of the main types of coring equipment that can be used to sample sediments from a variety of settings including lakes, the ocean, peat bogs, soils, and permafrost. The major advantages and disadvantages of each type of corer are also discussed.

River Leven (at Newby Bridge) freeze coring report

This is the River Leven (at Newby Bridge) freeze coring report produced by Lancaster University in 2000. This study looks at fine materials in river Leven that may have to be considered detrimental to successful salmonid spawning. Following an observed decline in quality of salmonid fisheries at the site an investigation was initiated to assess the extent of ingress of fine sediments into the spawning gravels. A broader picture was sought by sampling both above and below the weir and close to both banks of the river. A comparison of the fine sediment from each sample site was undertaken. All the freeze cores used in this report contained distinct horizontal strata down through their length. The cores often penetrated into a highly compacted layer of light grey coloured material. The upper surface of this highly compacted layer is considered as a boundary between fine materials of different origin. Considerable variability was observed in the median grain size (D50) of the gravels from the cores. In addition variability was observed in the thickness of the upper less compacted layers. The role of regulated river flow across the weir in clearing fines from river gravels is briefly considered.

River Crake (at Bouthrey Bridge) freeze coring report

This is the River Crake (at Bouthrey Bridge) freeze coring report produced by Lancaster University in 1999. This study looks at fine materials in river Crake at Bouthrey Bridge that may have to be considered detrimental to successful salmonid spawning. Following an observed decline in quality of salmonid fisheries at the site an investigation was initiated to assess the extent of ingress of fine sediments into the spawning gravels. Fine sediments from one potential source, upstream riverbanks, are also compared to those isolated from the spawning gravels. The percentage by weight of fine sediments for the six freeze cores, was found to be lower than first expected, given the visual appearance of the reach. However the fines were found to be distributed evenly down the cores with a marked absence of an upper, coarse gravel armour layer. In addition the median grain size (D50) of the six samples was generally low, falling to 6mm for core 5. The low median grain size and the absence of coarse grained upper strata are considered detrimental to the success rate of salmonid spawning.

Fine-root turnover rates of European forests revisited: an analysis of data from sequential coring and ingrowth cores

Background and Aims Forest trees directly contribute to carbon cycling in forest soils through the turnover of their fine roots. In this study we aimed to calculate root turnover rates of common European forest tree species and to compare them with most frequently published values. Methods We compiled available European data and applied various turnover rate calculation methods to the resulting database. We used Decision Matrix and Maximum-Minimum formula as suggested in the literature. Results Mean turnover rates obtained by the combination of sequential coring and Decision Matrix were 0.86 yr−1 for Fagus sylvatica and 0.88 yr−1 for Picea abies when maximum biomass data were used for the calculation, and 1.11 yr−1 for both species when mean biomass data were used. Using mean biomass rather than maximum resulted in about 30 % higher values of root turnover. Using the Decision Matrix to calculate turnover rate doubled the rates when compared to the Maximum-Minimum formula. The Decision Matrix, however, makes use of more input information than the Maximum-Minimum formula. Conclusions We propose that calculations using the Decision Matrix with mean biomass give the most reliable estimates of root turnover rates in European forests and should preferentially be used in models and C reporting.

Field report from sediment coring in peat for landscape analysis in Hjaltadalur, Skagafjörður, north Iceland 2010 : Sediment drilling in Hólar, Vidvik and Kolkuós, Hjaltadalur

This field report presents fieldwork undertaken in Hjaltadalur, Skagafjördur, northern Iceland during summer 2010. The main aim was to initiate coring in selected mires in order to determine the composition of organic material and sediments in the mires, sub-sample for sedimentological and palaeoecological analyses, and initiate advanced landscape analysis of Hjaltadalur. Three mires were selected for sediments coring in Hjaltadalur: Ástunga close to Kolkóus, Hólakot at Viðvik, and Hólar. All three represented a landscape transect in NW to SE direction, from close to the coast to valley interior, i.e. close to the old settlement at Hólar.

Grain size analysis of sediment coring site CRP-2 from the Ross Sea, Antarctica

The purpose of this note is to present results of grain size analyses from 118 samples of the CRP-2/2A core using sieve and Sedigraph techniques. The samples were selected to represent the range of facies encountered, and tend to become more widely spaced with depth. Fifteen came from the upper 27 m of Quaternary and Pliocene sediments, 62 from the early Miocene-late Oligocene strata (27 to 307 mbsf), and 41 from the early Oligocene strata beneath (307 to 624 mbsf). The results are intended to provide reference data for lithological descriptions in the core logs (Cape Roberts Science Team, 1999), and to help with facies interpretation. The analytical technique used for determining size frequency of the sand fraction in our samples (sieving) is simple, physical and widely practised for over a century. Thus it provides a useful reference point for analyses produced by other faster and more sophisticated techniques, such as the Malvern laser particle size analysis system (Woolfe et al., 2000), and estimates derived from measurements taken with down-hole logging tools (Bücker, pers. com., 1999).

Geochemical analysis of sediments from three coring sites in the Mediterranean

In a gravity core from the eastern Mediterranean Sea, a chemically and mineralogically distinct, 5.5-cm-thick layer is present above sapropel S-1 and overlain by hemipelagic marls. Calcite is completely absent in this exotic layer, dolomite is present only in small amounts, and the Cr concentrations are significantly enhanced. The layer was deposited primarily under reducing conditions, but the distributions of redox-sensitive elements show that a large part of the exotic layer is now oxidised by a downward-progressing oxidation front. Sediments from within the nearby anoxic, hypersaline Urania Basin are similar to those from the exotic layer, in particular in S-, C-, and O-isotope distributions of pyrite and dolomite, as well as increased Cr concentrations. Mud expulsion due to expansion of gas-rich mud is proposed to explain the presence of the exotic layer outside the Urania Basin. The deposition of an anoxic layer above S-1 shielded the sapropel from oxidation which resulted in the rare occurrence of a complete preservation of S-1 and provides the first minimum age for the start of anoxic mud accumulation in the Urania Basin.