Monitoring well interception with fractures in clayey till

When using monitoring wells for investigation of contaminant sources in clayey till, there is a high risk that fractures may cause mobile contaminants to bypass the monitoring wells. This paper indicates that the probability of interception between monitoring wells and hydraulic conductive fractures is often significantly less than 50%. Based on a field experiment and application of a calibrated discrete fracture matrix diffusion numerical model (FRAC3Dvs), the paper also evaluates pesticide-monitoring results for different positions of monitoring well screen relative to fractures. For well screens situated 0.25 and 2 m from a conductive fracture, the first concentrations of the pesticide metabolite (2,6 dichlorobenzamide, "BAM") would be measured two years and 18 years, respectively, after the contaminant had been transported into an underlying aquifer. In this way, underlying aquifers may be subjected to contamination by downward moving contamination without being observed in monitoring wells in the till.     

Biodegradation of Creosote Compounds: Comparison of Experiments at Different Scales

This paper compares the results of biodegradation experiments with creosote compounds performed at different scales. The experiments include field observations, field experiments, large-scale intact laboratory column experiments, model fracture experiments, and batch experiments. Most of the experiments were conducted with till or ground water from the field site at Ringe on the island of Funen. Although the experiments were conducted on different scales, they revealed that some phenomena—e.g., an extensive biodegradation potential of several of the creosote compounds, the inhibitory influence of the pyrroles on the biodegradation of benzene, and the biodegradation of benzothiophene occurs only in the presence of a primary substrate. The experiments show that some biodegradation processes of organic compounds may be common to different microorganisms.     

The Antonio Gramsci oil spill Impact on the littoral and benthic ecosystems

On 27 February 1979 the tanker Antonio Gramsci grounded off Ventspils (USSR) in the Baltic Sea. Some 5000–6000 t of crude oil were spilled, and drifted towards the archipelago of Stockholm (Sweden) and Åland (Finland). About 500 t oil was mechanically recovered in the Åland area. The effects of the oil on the littoral communities were studied for two months after the spill, and for the benthic community the long-term changes were recorded for three years. The immediate effects were small in the uppermost littoral (the Cladophora belt), but in the lower littoral (the Fucus belt) severe effects were recorded. Meiofaunal densities decreased in crustacean and mollusc species, but remained stable for the total community. Macrofaunal long-term changes could not be linked to the oil spill. Thus the effects of the oil were rather small, although a large area was contaminated.     

Chemical and bacteriological studies of some culturally influenced danish lakes

Four eutrophicated lakes situated on the Danish island of Lolland were investigated. The result of chemical analyses of the water, and the determination of heavy metals in the sludge by means of flameless atomic absorption spectrophotometry are given in the tables 1–5. Bacteriological investigations of sediments from the lakes, both conventional analyses and also more special analyses, e.g. of cellulolytic bacteria, chitinoclastic bacteria; lignin decomposing actinomycetes were counted on both tannic acid agar and gallic acid agar, and saprophyticActinomyces on Henrici’s asparagine substrate, tables 6–9.     

Die Sedimente des zentralen Tyrrhenischen Meeres

Summary In the core No. 205 (Fig. 1), four divisions (A–D) have been distinguished, each commencing with a bed of volcanic ash which records an epoch of intense activity in the volcanic source region. The volcanic beds are chiefly of two types, viz. 1) beds of wind-born ashes, and 2) masses of pumice floated on the sea and subsequently crushed by the action of the waves. The turbidity current deposits are characterized int. a l. by gravitative grading of a distinctive type, and by an abundance of benthonic micro-organisms. Throughout the sequence, the pelitic sediments are characterized by the paragenesis: illite, kaolinite, and montmorillonite.The boundary between Divisions C and B markes an important change in the geographical milieu, recorded in the stratigraphy of the core not only petrographically but also biologically.     

Depth distribution of calcareous sediments in the Mesozoic and Cenozoic North Atlantic Ocean

The upper Mesozoic and Cenozoic distribution of calcareous, biogenic particles which are produced by planktonic foraminifers and nannoplankton and which are the most important components of pelagic sediments since mid-Mesozoic times, has been reconstructed using data from North Atlantic deep-sea drill sites. Two phases of sedimentation of carbonate-rich sediments are separated by an interval from 100 to 80 m.y. B.P. when CaCO₃ particles were diluted by chiefly terrigenous material. Prior to 100 m.y. B.P. the highest concentrations of calcareous matter were confined to the deepest part of the then 4–4.5 km deep North Atlantic. After 80 m.y. B.P. sediments with high concentrations of calcareous matter have been deposited above 3 km paleodepth, but during the last 25 m.y. also between 4 and 5.5 km paleo-water depth. The latter occurrence is associated with indications of downslope displacement of calcareous material into the abyssal plains of the deepest parts of the North Atlantic.     

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Ohne Zusammenfassung     

The magnetic fabric of some dolerite intrusions,northeast Spitsbergen; implications for their mode of emplacement

The titanomagnetite fabric of some dolerites from two areas of northeast Spitsbergen, Lomfjorden and the Bastian, and Rønnbeck islands have been studied by means of magnetic susceptibility anisotropy measurements. The shape and orientation of the susceptibility ellipsoids were determined with an a.c. bridge. Both areas showed a dominating magnetic foliation in the horizontal plane. A weakly developed preferred orientation of the maximum (K^I) and intermediate (K^II) susceptibility axis within the magnetic foliation plane was found, the K^I-axis striking predominantly E-W and the K^II-axis striking N-S. The magnetic fabric is interpreted as resulting from horizontal movement of magma. It is concluded that the Bastian and Rønnbeck islands are the relics of one or more larger sills.