No abstract

A comprehensive analytical investigation of the sorption behaviour of a large selection of over-the-counter, prescribed pharmaceuticals and illicit drugs to agricultural soils and freeze-dried digested sludges is presented. Batch sorption experiments were carried out to identify which compounds could potentially concentrate in soils as a result of biosolid enrichment. Analysis of aqueous samples was carried out directly using liquid chromatography-tandem mass spectrometry (LC-MS/MS). For solids analysis, combined pressurised liquid extraction and solid phase extraction methods were used prior to LC-MS/MS. Solid-water distribution coefficients (K(d)) were calculated based on slopes of sorption isotherms over a defined concentration range. Molecular descriptors such as log P, pK(a), molar refractivity, aromatic ratio, hydrophilic factor and topological surface area were collected for all solutes and, along with generated K(d) data, were incorporated as a training set within a developed artificial neural network to predict K(d) for all solutes within both sample types. Therefore, this work represents a novel approach using combined and cross-validated analytical and computational techniques to confidently study sorption modes within the environment. The logarithm plots of predicted versus experimentally determined K(d) are presented which showed excellent correlation (R(2) > 0.88), highlighting that artificial neural networks could be used as a predictive tool for this application. To evaluate the developed model, it was used to predict K(d) for meclofenamic acid, mefenamic acid, ibuprofen and furosemide and subsequently compared to experimentally determined values in soil. Ratios of experimental/predicted K(d) values were found to be 1.00, 1.00, 1.75 and 1.65, respectively.

[1] Marine pockmarks are a specific type of seabed geological setting resembling craters or pits and are considered seabed surface expressions of fluid flow in the subsurface. A large composite pockmark on the Malin Shelf, off the northern coast of Ireland was surveyed and ground truthed to assess its activity and investigate fluid related processes in the subsurface. Geophysical (including acoustic and electromagnetic) data confirmed the subsurface presence of signatures typical of fluids within the sediment. Shallow seismic profiling revealed a large shallow gas pocket and typical gas related indicators such as acoustic blanking and enhanced reflectors present underneath and around the large pockmark. Sulphate profiles indicate that gas from the shallow reservoir has been migrating upwards, at least recently. However, there are no chimney structures Copyright 2012 by the American Geophysical Union 1 of 18 observed in the sub-bottom data and the migration pathways are not apparent. Electromagnetic data show slightly elevated electrical conductivity on the edges of the pockmarks and a drop below regional levels within the confines of the pockmark, suggesting changes in physical properties of the sediment. Nuclear Magnetic Resonance (NMR) experiments were employed to characterize the organic component of sediments from selected depths. Very strong microbial signatures were evident in all NMR spectra but microbes outside the pockmark appear to be much more active than inside. These observations coincide with spikes in conductivity and the lateral gas bearing body suggesting that there is an increase in microbial activity and biomass when gas is present.

During the Irish National Seabed Survey (INSS) in 2003, a gas related pockmark field was discovered and extensively mapped in the Malin Shelf region (NW Ireland). In summer 2006, additional complementary data involving core sample analysis, multibeam and single-beam backscatter classification, and a marine controlled-source electromagnetic survey were obtained in specific locations.This multidisciplinary approach allowed us to map the upper 20 m of the seabed in an unprecedented way and to correlate the main geophysical parameters with the geological properties of the seabed. The EM data provide us with information about sediment conductivity, which can be used as a proxy for porosity and also to identify the presence of fluid and fluid migration pathways. We conclude that, as a whole, the central part of the Malin basin is characterized by higher conductivities, which we interpret as a lithological change. Within the basin several areas are characterized by conductive anomalies associated with fluid flow processes and potentially the presence of microbial activity, as suggested by previous work. Pockmark structures show a characteristic electrical signature, with high-conductivity anomalies on the edges and less conductive, homogeneous interiors with several high-conductivity anomalies, potentially associated with gas-driven microbial activity.

24 Methane-derived authigenic carbonate (MDAC) mound features at the Codling Fault 25Zone (CFZ), located in shallow waters (50 to 120 m) of the western Irish Sea were 26 investigated and provide a comparison to deep sea MDAC settings. Carbonates 27 conststed of aragonite as the major mineral phase, with 13 C values as low as -50‰. 28These isotope signatures, together with the co-precipitation of framboidal pyrite 29 confirm that anaerobic oxidation of methane (AOM) is an important process 30 mediating methane release to the water column and the atmosphere in this region. The 31 13 C depletion of bulk carbonate and sampled gas (-70‰) suggests a biogenic source, 32 but significant mixing of thermogenic gas and depletion of the original isotope 33signature cannot be ruled out. Active seepage was recorded from one mound and 34 together with extensive areas of reduced sediment, confirms that seepage is ongoing. 35The mounds appear to be composed of stacked pavements that are largely covered by 36 sand and extensively eroded. The CFZ mounds are colonized by abundant Sabellaria 37 polychaetes and possible Nemertesia hydroids, which benefit indirectly from available 38 hard substrate. In contrast to deep sea MDAC settings where seep-related macrofauna 39 are common reported, seep-specialist fauna appear to be lacking at the CFZ. In 40 addition, unlike MDAC in deep waters where organic carbon input from 41 photosynthesis is limited, lipid biomarkers and isotope signatures related to marine 42 planktonic production (e.g. sterols, alkanols) were most abundant. Evidence for 43 microbes involved in AOM was limited from samples taken; possibly due to this 44 dilution effect from organic matter derived from the photic zone, and will require 45 further investigation. 46 47 3