Structure and development of the southern Moroccan continental shelf     

William P Dillon 《Marine Geology》1974,16(3):121-143

The structure of the continental shelf off southern Morocco was studied by means of 2,100 km of seismic reflection profiles, magnetic and bathymetric surveys, and dredge samples. The research area lies off four geologic divisions adjacent to the coast: the Atlas Mountains; the Souss Trough; the Anti-Atlas Mountains; and the Aaiun Basin. The continental shelf, along with the western Atlas Mountains, the western Souss Trough, and the entire Aaiun Basin, has subsided along a normal fault-flexure system. This system runs along the shore at the Anti-Atlas Mountains, and cuts off this cratonic block from the shelf subsidence. The shelf is narrow and characterized by out-building off the Anti-Atlas range, whereas it is broader and characterized by upbuilding to the north and south. Deposition was essentially continuous at least from Early Cretaceous through Eocene time. Published work suggests that the last cycle of sedimentation began during Permian rifting. After Eocene time, most sediments carried to the shelf must have bypassed it and gone to construct the slope and rise or to the deep sea. Tertiary orogenies caused extensive folding of Mesozoic and early Tertiary deposits off the Atlas Mountains.  相似文献   

Sea-floor methane blow-out and global firestorm at the K–T boundary     

M. D. Max  W. P. Dillon  C. Nishimura  B. G. Hurdle 《Geo-Marine Letters》1998,18(4):285-291

A previously unsuspected source of fuel for the global firestorm recorded by soot in the Cretaceous–Tertiary impact layer may have resided in methane gas associated with gas hydrate in the end-Cretaceous seafloor. End-Cretaceous impact-generated shock and megawaves would have had the potential to initiate worldwide oceanic methane gas blow-outs from these deposits. The methane would likely have ignited and incompletely combusted. This large burst of methane would have been followed by longer-term methane release as a part of a positive thermal feedback in the disturbed ocean-atmosphere system.  相似文献   

A S-isotope approach to determine the relative contribution of redox processes to net SO₄ export from upland, and wetland-dominated catchments     

M.C. Eimers  P.J. Dillon 《Geochimica et cosmochimica acta》2004,68(18):3665-3674

Reoxidation of S stored in lowlands after summer droughts has been reported to be responsible for the excess SO₄ export observed in many catchments in south central Ontario. Stable S isotopes can be used to identify the source of SO₄ export in stream water, and are particularly well suited to evaluating zones of dissimilatory SO₄ reduction (DSR) and the contribution of oxidation of reduced S species to stream SO₄. The Plastic Lake-1 (PC1) stream drains an upland coniferous forest and then passes through a Sphagnum-dominated swamp before discharging to Plastic Lake. Measurements of SO₄ fluxes and isotope ratios were used to determine the source of net SO₄ export and the contribution of redox processes to S retention and export in the upland and wetland, respectively. Mass balance budgets for the years 1999/00 and 2000/01, which had comparatively wet summers, indicated that the upland part of the catchment consistently exported SO₄ in excess of bulk deposition inputs. In contrast, mass budget calculations for the swamp indicated a net retention of 3 and 2 g S-SO₄/m² of wetland area, in 1999/00 and 2000/01 respectively. Higher δ³⁴SO₄ ratios and lower SO₄ concentrations in the swamp outflow (average +8.6 ± 2.6‰; 1.5 ± 0.6 mg S-SO₄/L) compared to the inflow draining the upland (+5.4 ± 0.7‰; 2.4 ± 0.3 mg S-SO₄/L) indicated that DSR was at least partly responsible for net SO₄ retention in the swamp. Isotope values in upland stream water (+5.7 ± 0.7‰) were only slightly higher than values in bulk deposition (average +5.1 ± 0.6‰) and soil leachate (+4.4 ± 0.4‰) over the 2-year period of study. Similar δ³⁴SO₄ values in upland stream water compared to deposition and soil leachate, despite substantial variations in water table height in the streambed (92 cm), suggest that reoxidation of reduced sulphides is not an important contributor to SO₄ export from the upland. Rather, net SO₄ export from the upland subcatchment is likely due to net release from upland soil, and slight differences in δ³⁴SO₄ between bulk deposition and soil leachate are consistent with SO₄ release from organic S forms.  相似文献   

Future management of aquifer recharge   总被引：1，自引：3，他引：1  

Peter Dillon 《Hydrogeology Journal》2005,13(1):313-316

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Hydraulic evaluation of aquifer storage and recovery (ASR) with urban stormwater in a brackish limestone aquifer     

Paul Pavelic  Peter J. Dillon  Karen E. Barry  Nabil Z. Gerges 《Hydrogeology Journal》2006,14(8):1544-1555

A 5-year aquifer storage and recovery trial at Andrews Farm in South Australia involving the injection of more than 250 ML (250,000 m³) of fresh but turbid stormwater into a brackish limestone aquifer over 4 years and recovery of 150 ML in the fifth provided the opportunity to evaluate rates of clogging and unclogging and the potential to recover water suitable for irrigation supplies. Results reveal there is some clogging by injected sediment, but only to a relatively small degree considering the high suspended solid concentrations and moderate aquifer transmissivity. This clogging was offset by increased matrix porosity through calcite dissolution and by routine well redevelopments after each 40 ML of injection. No significant microbial clogging occurred. Breakthrough responses at three observation wells and the proportion of injectant in the recovered water were determined from chloride data. Temperature and caliper profiles clearly indicate the heterogeneous nature of the aquifer that is attributed, in part, to sand removal during the initial well development. The recovery efficiency was greater than 60%. The trial demonstrates that urban stormwater containing high and variable particulate levels, which receives only passive pre-treatment and is not disinfected, can be used to freshen a heterogeneous brackish aquifer to create a useful water resource.  相似文献   

Attenuation of Two Estrogen Compounds in Aquifer Materials Supplemented with Sewage Effluent   总被引：2，自引：0，他引：2  

Guang-Guo Ying  Rai S. Kookana  Peter Dillon 《Ground Water Monitoring & Remediation》2004,24(2):102-107

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Effect of graded levels of dietary carbohydrate on growth,feed utilisation and intestinal microbial community structure in dusky kob Argyrosomus japonicus fed a pelleted diet     

NC Mabasa  PJ Britz  CLW Jones  A Nel 《African Journal of Marine Science》2018,40(3):267-277

The ability to utilise carbohydrates is limited for many predatory marine fishes. Graded levels of dietary carbohydrate (4.1–24.6%) were formulated using pregelatinised maize starch, to determine optimal levels for dusky kob Argyrosomus japonicus, an emerging mariculture finfish for which pelleted feeds are being developed. Specific growth rate increased with an increase in the carbohydrate level up to 16.72%, after which it declined. Feed utilisation followed a similar trend, with the best feed conversion ratio (1.28) and protein efficiency ratio (1.76) recorded at 16.4% carbohydrate. Lipid vacuolisation of the hepatocytes was evident in all livers examined, with melano-macrophage aggregates in those of fish fed 24.6% carbohydrate suggesting starvation. Gut bacterial community profiles were variable but were not influenced by dietary carbohydrate level and differed mostly between fish fed trout feed prior to the trial and those fed experimental diets containing starch. The dusky kob were able to clear glucose from their blood when fed up to 16.4% carbohydrate, but glucose removal was not achieved at 24.6% carbohydrate. In conclusion, dusky kob has a limited ability to utilise cooked starch as a carbohydrate source, which may be included in pelleted feed at 16.4% without adverse effects. For this species, levels of dietary carbohydrate above this may result in symptoms consistent with physiological breakdown, including reduced growth, reduced feed intake and feed conversion efficiency, prolonged hyperglycaemia, liver pathology and altered microbial communities in the foregut.  相似文献   

Strategic priorities for assessing ecological impacts of marine renewable energy devices in the Pentland Firth (Scotland,UK)     

Mark A. Shields  Lora Jane Dillon  David K. Woolf  Alex T. Ford 《Marine Policy》2009

The Pentland Firth, located between the north coast of mainland Scotland (UK) and the Orkney Islands, is recognised as an excellent location for the utilisation of tidal stream technology. Potential ecological impacts associated with tidal stream technology may ultimately depend on device design, array size and deployment location. Available ecological data for the Pentland Firth is summarised and strategic priorities for assessing ecological impacts are provided. Baseline data on marine species and habitats in the Pentland Firth is severely lacking and consequently the integrity of any environmental impact assessment could be compromised by this lack of data.  相似文献   

Effect of ultraviolet and visible radiation on iron lability in boreal and artificial waters     

Nadia Kelton  Lewis A. Molot  Peter J. Dillon 《Aquatic Sciences - Research Across Boundaries》2007,69(1):86-95

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Effect of pH on photo-oxidation of dissolved organic carbon by hydroxyl radicals in a coloured, softwater stream   总被引：3，自引：1，他引：2  

Lewis A. Molot  Jeff J. Hudson  Peter J. Dillon  Sean A. Miller 《Aquatic Sciences - Research Across Boundaries》2005,67(2):189-195

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