Arsenic mobility and impact on recovered water quality during aquifer storage and recovery using reclaimed water in a carbonate aquifer     

J.L. Vanderzalm  P.J. Dillon  K.E. Barry  K. Miotlinski  J.K. Kirby  C. Le Gal La Salle 《Applied Geochemistry》2011,26(12):1946-1955

Arsenic release from aquifers can be a major issue for aquifer storage and recovery (ASR) schemes and understanding the processes that release and attenuate As during ASR is the first step towards managing this issue. This study utilised the first and fourth cycles of a full scale field trial to examine the fate of As within the injectant plume during all stages of the ASR cycle, and the resultant water quality. The average recovered As concentration was greater than the source concentration; by 0.19 μmol/L (14 μg As/L) in cycle 1 and by 0.34 μmol/L (25 μg As/L) in cycle 4, indicating that As was being released from the aquifer sediments during ASR and the extent of As mobilisation did not decline with subsequent cycles. In the injection phase, As mobilisation due to oxidation of reduced minerals was limited to an oxic zone in close proximity to the ASR well, while desorption from Fe oxyhydroxide or oxide surfaces by injected P occurred further in the near well zone (0–4 m from the ASR well). With further aquifer passage during injection and greater availability of sorption sites there was evidence of attenuation via adsorption to Fe oxyhydroxides which reduced concentrations on the outer fringes of the injectant plume. During the period of aquifer storage, microbial activity resulting from the injection of organic matter resulted in increased As mobility due to reductive Fe oxyhydroxide dissolution and the subsequent loss of sorption sites and partial reduction of As(V) to the more mobile As(III). A reduced zone directly around the ASR well produced the greatest As concentration and illustrated the importance of Fe oxyhydroxides for controlling As concentrations. Given the small spatial extent of this zone, this process had little effect on the overall recovered water quality.  相似文献   

Manganese cycling in central Ontario forests: Response to soil acidification     

Shaun A. Watmough  M. Catherine Eimers  Peter J. Dillon 《Applied Geochemistry》2007

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Relationships between body size and trophic position of consumers in temperate freshwater lakes     

Persaud  A. D.  Dillon  P. J.  Molot  L. A.  Hargan  K. E. 《Aquatic Sciences - Research Across Boundaries》2012,74(1):203-212

Animal body size is a driving force behind trophic interactions within biological communities, yet few studies have explored relationships between body size and trophic position (based on δ¹⁵N) at a broad-scale in freshwater lakes. Therefore, our goals were to (1) determine whether body size is a good predictor of trophic position for multiple pelagic zooplankton taxa and fish communities, and (2) examine how body size-trophic position relationships at the community level compare to species level for fish. Zooplankton and fish were collected from 12 and 7 lakes, respectively, located in the Kawarthas, southern Ontario, Canada. The results indicated that for zooplankton, significant positive but different relationships were found between body size and trophic position for cladocerans, in general, and Daphnia, but not Holopedium. For fish, at the lake community level six out of seven relationships were positive and significant, but again, different among lakes. In contrast, at the species level only three of eight species-specific relationships were significant. Furthermore, for two widespread species, Perca flavescens and Micropterus dolomieu, significant differences were found between community- and lake-specific species relationships. Our community-level models and most species-level models provide evidence that trophic interactions in freshwater lakes are size-based. These results demonstrate that general species models should be applied with caution when using body size to predict trophic position. Additionally, the predictive power of some relationships found here is questionable since, albeit significant, their strengths are generally low. Together, our results suggest that body size may have limited use in predicting trophic position of some biota in temperate freshwater lakes.  相似文献   

Relative Recovery of Thermal Energy and Fresh Water in Aquifer Storage and Recovery Systems   总被引：1，自引：0，他引：1       下载免费PDF全文

K. Miotliński  P.J. Dillon 《Ground water》2015,53(6):877-884

This paper explores the relationship between thermal energy and fresh water recoveries from an aquifer storage recovery (ASR) well in a brackish confined aquifer. It reveals the spatial and temporal distributions of temperature and conservative solutes between injected and recovered water. The evaluation is based on a review of processes affecting heat and solute transport in a homogeneous aquifer. In this simplified analysis, it is assumed that the aquifer is sufficiently anisotropic to inhibit density‐affected flow, flow is axisymmetric, and the analysis is limited to a single ASR cycle. Results show that the radial extent of fresh water at the end of injection is greater than that of the temperature change due to the heating or cooling of the geological matrix as well as the interstitial water. While solutes progress only marginally into low permeability aquitards by diffusion, conduction of heat into aquitards above and below is more substantial. Consequently, the heat recovery is less than the solute recovery when the volume of the recovered water is lower than the injection volume. When the full volume of injected water is recovered the temperature mixing ratio divided by the solute mixing ratio for recovered water ranges from 0.95 to 0.6 for ratios of maximum plume radius to aquifer thickness of 0.6 to 4.6. This work is intended to assist conceptual design for dual use of ASR for conjunctive storage of water and thermal energy to maximize the potential benefits.  相似文献   

The use of sulfur hexafluoride (SF₆) as a tracer of septic tank effluent in the Florida Keys     

K. S. Dillon  D. R. Corbett  J. P. Chanton  W. C. Burnett  D. J. Furbish 《Journal of Hydrology》1999,220(3-4):129-140

To determine the fate and movement of sewage derived contaminants and their possible interaction with surface waters in the Florida (USA) Keys, two types of experiments were conducted using SF₆ as an artificial tracer. The first type of experiment examined fluid flow from septic tanks placed in Miami Oolite on Big Pine Key, where there is a shallow freshwater lens overlying saline groundwaters. Here groundwater transport rates were constrained to be between 0.11 and 1.87 m/h, travelling in an easterly direction. The second type of experiment took place on Key Largo where there is no freshwater aquifer and the matrix of the aquifer is solely the more porous Key Largo limestone. Here we injected the tracer into a shallow well which was screened from 0.6 to 10 m. This allowed us to evaluate groundwater movement in the shallow upper portion of the aquifer, the area to which inputs by septic tanks occur. Groundwater transport rates in the Upper Keys were as great as 3.7 m/h and were controlled by the Atlantic tide. SF₆ laden groundwater plumes moved back and forth due to tidal pumping and reached nearby surface waters within 8 h.  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》1999,18(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. Received: 16 September 1998 / revision received: 11 January 1999  相似文献   

Oxygen consumption in the shrimp,Palaemonetes pugio,exposed to fluctuating temperatures and food contaminated with the diaromatic petroleum hydrocarbon,dimethylnaphthalene     

T.M. Dillon 《Estuarine, Coastal and Shelf Science》1983,16(4):403-413

Oxygen consumption rates (V?o₂) in the grass shrimp Palaemonetes pugio were determined after a 32 day exposure to fluctuating temperatures (FT) (18–22°C) and/or dimethylnaphthalene (DMN)-contaminated food (0·24 μg DMN g wet wt^?1) and again after a 16 day recovery period of stable temperatures (20°C) and uncontaminated food. Ingestion of DMN-contaminated food for 32 days resulted in elevated V?>o₂ in shrimp exposed to declining oxygen concentrations. After the 32 day exposure period, FT had no significant effect on V?o₂ at 15, 20 and 25°C, tissue V?o₂ and V?o₂ in declining oxygen. Hemolymph copper concentrations were significantly depressed in shrimp exposed to DMN-contaminated food. After the 16 day recovery period, shrimp from the FT regime exhibited depressed V?o₂ when exposed to 25°C but not to 15°C. These depressed respiratory rates were offset by the stimulatory effect of DMN-contaminated food.These respiration studies were generally unproductive in explaining the previously reported effects of FT and DMN-contaminated food on the survival of P. pugio under hypoxic conditions.  相似文献   

Geochemical processes during five years of aquifer storage recovery   总被引：4，自引：0，他引：4  

Herczeg AL  Rattray KJ  Dillon PJ  Pavelic P  Barry KE 《Ground water》2004,42(3):438-445

A key factor in the long-term viability of aquifer storage recovery (ASR) is the extent of mineral solution interaction between two dissimilar water types and consequent impact on water quality and aquifer stability. We collected geochemical and isotopic data from three observation wells located 25, 65, and 325 m from an injection well at an experimental ASR site located in a karstic, confined carbonate aquifer in South Australia. The experiment involved five major injection cycles of a total of 2.5 x 10(5) m3 of storm water (total dissolved solids [TDS] approximately 150 mg/L) into the brackish (TDS approximately 2400 mg/L) aquifer. Approximately 60% of the mixture was pumped out during the fifth year of the experiment. The major effect on water quality within a 25 m radius of the injection well following injection of storm water was carbonate dissolution (35 +/- 6 g of CaCO3 dissolved/m3 of aquifer) and sulfide mineral oxidation (50 +/- 10 g as FeS2/m3 after one injection). < 0.005% of the total aquifer carbonate matrix was dissolved during each injection event, and approximately 0.2% of the total reduced sulfur. Increasing amounts of ambient ground water was entrained into the injected mixture during each of the storage periods. High 14C(DIC) activities and slightly more negative delta13C(DIC) values measured immediately after injection events show that substantial CO2(aq) is produced by oxidation of organic matter associated with injectant. There were no detectable geochemical reactions while pumping during the recovery phase in the fifth year of the experiment.  相似文献   

Mercury and the estuarine marsh clam, Rangia cuneata gray. II. uptake, tissue distribution and depuration     

T. M. Dillon  J. M. Neff 《Marine environmental research》1978,1(1):67-77

During a two-week period, Rangia rapidly accumulates mercury (as mercuric chloride) from dilute solution (0·03–0·05 ppm) with the majority being located in gill and mantle tissue. Initial depuration (5 h) in clean seawater is rapid in all tissues. From 10–192 h concentrations of mercury in gill, foot and adductor muscles remain stable while mantle, haemolymph and viscera levels continue to fluctuate in a manner suggesting internal redistribution of mercury. After eight days of depuration, the viscera contains the most mercury and appears to be the only tissue to increase its proportionate share of the total tissue mercury. After fifteen weeks of depuration, residual mercury in whole clams is about 20% of initial concentrations. Acute decreases in salinity (15% S to 2% S) enhance Rangia's ability to depurate mercury.  相似文献   

Erosional channels on the shoreface of Nauset Beach,Cape Cod,Massachusetts     

S. W. Needell  W. P. Dillon  H. J. Knebel 《Geo-Marine Letters》1982,2(1-2):61-64

Many channels (1 to 3 m relief)_are located offshore of Nauset Beach, Cape Cod, Massachusetts, in water 4 to 18 m deep. The channels are oblique to the shoreline, are spaced approximately 260 m apart, and deepen seaward. The southern flank of each channel is rippled whereas the northern flank and interchannel areas are smooth. The origin of the channels is unknown. They probably formed by erosion of the shoreface, perhaps by rip-current circulation during storm conditions or by rip-current circulation under quiet conditions. The channels may control current flow and thereby maintain themselves even though formative conditions may no longer exist.  相似文献