Reservoir Sites Research Articles

Drug delivery strategies and systems for HIV/AIDS pre-exposure prophylaxis and treatment

The year 2016 will mark an important milestone — the 35th anniversary of the first reported cases of HIV/AIDS. Antiretroviral Therapy (ART) including Highly Active Antiretroviral Therapy (HAART) drug regimens is widely considered to be one of the greatest achievements in therapeutic drug research having transformed HIV infection into a chronically managed disease. Unfortunately, the lack of widespread preventive measures and the inability to eradicate HIV from infected cells highlight the significant challenges remaining today. Moving forward there are at least three high priority goals for anti-HIV drug delivery (DD) research: (1) to prevent new HIV infections from occurring, (2) to facilitate a functional cure, i.e., when HIV is present but the body controls it without drugs and (3) to eradicate established infection. Pre-exposure Prophylaxis (PrEP) represents a significant step forward in preventing the establishment of chronic HIV infection. However, the ultimate success of PrEP will depend on achieving sustained antiretroviral (ARV) tissue concentrations and will require strict patient adherence to the regimen. While first generation long acting/extended release (LA/ER) DD Systems (DDS) currently in development show considerable promise, significant DD treatment and prevention challenges persist. First, there is a critical need to improve cell specificity through targeting in order to selectively achieve efficacious drug concentrations in HIV reservoir sites to control/eradicate HIV as well as mitigate systemic side effects. In addition, approaches for reducing cellular efflux and metabolism of ARV drugs to prolong effective concentrations in target cells need to be developed. Finally, given the current understanding of HIV pathogenesis, next generation anti-HIV DDS need to address selective DD to the gut mucosa and lymph nodes. The current review focuses on the DDS technologies, critical challenges, opportunities, strategies, and approaches by which novel delivery systems will help iterate towards prevention, functional cure and eventually the eradication of HIV infection.

How Much HIV is Alive? The Challenge of Measuring Replication Competent HIV for HIV Cure Research

How Much HIV is Alive? The Challenge of Measuring Replication Competent HIV for HIV Cure Research

Spatial Distribution of Gmelinoides fasciatus Steb. in Thermally Polluted Water (Belovo Reservoir, Southwest Siberia)

Gmelinoides fasciatus (Stebbing, 1899) is a Baikal endemic amphipod that has recently become widespread in Eurasia. This species accidentally entered the cooling reservoir of the Belovo power plant and became successfully naturalised there. This study describes the peculiarities of G. fasciatus distribution in reservoir sites with different thermal regimes and analyses the environmental factors that limit its spread. The use of heating areas for prevernal breeding promoted the rapid expansion of G. fasciatus in the cooling reservoir. Silted soils, depths greater than 1 m and water heating above 26°C limit the dissemination of G. fasciatus in the reservoir. Invasion of G. fasciatus in the Belovo reservoir has not caused the extinction of the indigenous species Gammarus lacustris. The structural characteristics of aboriginal communities at unpopulated and populated by G. fasciatus zone of reservoir were not statistically different. Invasion of G. fasciatus did not aggravate the competitive interactions in the benthic communities.

Monont'sa pumped-storage power project, Lesotho

This paper describes the pre-feasibility design of a high-head pumped-storage scheme in Lesotho. The underground powerhouse accommodates four 300 MW Francis pump turbines of regulated double-stage type achieving net heads of 723 m and 696 m in pumping and generating modes, respectively. Power drawn from the grid at off-peak periods will be regenerated at peak periods. The generation capacity is 1200 MW for 21 h. Roller-compacted concrete and concrete-faced rock-fill dams were selected for the particular reservoir sites. The headrace and tailrace tunnels, pressure shaft and manifold were concrete lined and sited where available minimum in situ rock stresses can safely contain internal pressures. Penstocks were steel lined. A twin-cavern arrangement was selected for the powerhouse set 800 m below ground. Features include downward demountable turbine runners in the machine cavern and rapid-acting bonneted draft tube gates accessed from the transformer cavern. A system of non-waterway tunnels provides access, separate emergency escape, ventilation and power cable routing to the surface switchyard. This paper addresses the energy characteristics and cycle efficiency of the project, and the considerations involved in the selection of the hydro-mechanical plant, electro-mechanical plant and civil works.

A reservoir siting tool for North Carolina: System design & operations for screening and evaluation

The North Carolina Reservoir Siting Tool (“NC-RES”) is a web-based, comprehensive, geographic information system designed to assist non-specialist and non-scientific users in carrying out first-pass, basic screening assessments of sites for potential municipal, county, or state reservoir locations. The tool operates based on terrain data, and is designed to take advantage of web mapping technology and the availability of North Carolina's LiDAR-derived, high-resolution digital terrain data. The tool presents users with an easy-to-use, “point and click” mapping interface and provides a variety of data and analyses about proposed reservoir sites, including quantitative information about reservoir inundation areas, drainage basins, and the effects of a proposed reservoir on the inundation and drainage areas. This paper provides a basic description of the processing framework and underlying data of the NC-RES tool as an automated approach to potential reservoir site evaluation and screening.

CNS reservoirs for HIV: implications for eradication

Controversy exists as to whether the central nervous system (CNS) serves as a reservoir site for HIV, in part reflecting the varying perspectives on what constitutes a ‘reservoir’ versus a mere site of latent viral integration. However, if the CNS proves to be a site of HIV persistence capable of replicating and reseeding the periphery, leading to failure of virological control, this privileged anatomical site would need dedicated consideration during the development of HIV cure strategies. In this review we discuss the current literature focused on the question of the CNS as a reservoir for HIV, covering the clinical evidence for continued CNS involvement despite suppressive therapy, the theorised dynamics of HIV integration into the CNS, as well as studies indicating that HIV can replicate independently and compartmentalise in the CNS. The unique cellular and anatomical sites of HIV integration in the CNS are also reviewed, as are the potential implications for HIV cure strategies.

PD2-03 NONINFECTED PENILE PROSTHESES CULTURE DURING REVISION SURGERIES; COMPARISON BETWEEN ANTIBIOTIC COATED AND UNCOATED DEVICES

You have accessJournal of UrologySexual Function/Dysfunction/Andrology: Penis/Testis/Urethra: Benign Disease1 Apr 2015PD2-03 NONINFECTED PENILE PROSTHESES CULTURE DURING REVISION SURGERIES; COMPARISON BETWEEN ANTIBIOTIC COATED AND UNCOATED DEVICES Seyfettin Ciftci, Tijen Nemut, Melih Culha, Hasan Yilmaz, Murat Ustuner, Ufuk Yavuz, and Levend Ozkan Seyfettin CiftciSeyfettin Ciftci More articles by this author , Tijen NemutTijen Nemut More articles by this author , Melih CulhaMelih Culha More articles by this author , Hasan YilmazHasan Yilmaz More articles by this author , Murat UstunerMurat Ustuner More articles by this author , Ufuk YavuzUfuk Yavuz More articles by this author , and Levend OzkanLevend Ozkan More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2015.02.186AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Some of the clinically uninfected penile prostheses have organisms growing in the implant spaces. These organisims can be cultured during revision surgeries. Aim of this study is to investigate the bacterial growth on uninfected devices and compare antibiotic coated and noncoated implants. METHODS The charts of the 71 patients who underwent revision surgeries for penile prosthesis between 1995 to 2013 were reviewed. Swab cultures were routinely obtained the corporal,pump or reservoir site during the operation. If a bacterial biofilm was determined on the prosthesis, it was also cultured. 31 devices were antibiotic coated prosthesis, while 40 of the implants were noncoated. RESULTS 6 different organisms were cultured from 18 patients. 4 of the devices were antibiotic coated and the other 14, noncoated devices. Staphylococcus Epidermidis was the most common organism, while Bacteriodes vulgatus, Staphylococcus Hominis, Beta Hemolitic Streptococcus, E.coli and Proteus Mirabilis were also cultured. All patients who had positive cultures were treated with appropiate antibiotics for four weeks postoperatively. Mean follow-up time was 41 months ranged from 8 to 82 months. One prosthesis(noncoated) became clinically infected in the follow-up period with a totally different organism. Ratios of the positive cultures of antibiotic coated and noncoated devices were 13% and 35% respectively and the result is significant(p= 0.00254). CONCLUSIONS Positive bacterial cultures are present on uninfected penile prostheses at revision surgeries in some of the patients. Antibiotic coated prostheses have much less positive cultures than noncoated devices. © 2015 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 193Issue 4SApril 2015Page: e41 Advertisement Copyright & Permissions© 2015 by American Urological Association Education and Research, Inc.MetricsAuthor Information Seyfettin Ciftci More articles by this author Tijen Nemut More articles by this author Melih Culha More articles by this author Hasan Yilmaz More articles by this author Murat Ustuner More articles by this author Ufuk Yavuz More articles by this author Levend Ozkan More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

23 Invited lecture: Tumor–stroma interactions promote operational flexibility in cancer progression

Malignant cancer cells do not act as lone wolves to achieve metastasis, as they exist within a complex ecosystem consisting of an extracellular matrix scaffold populated by carcinoma-associated fibroblasts (CAFs), endothelial cells and immune cells (De Wever and Mareel, J Pathol, 2003; De Wever et al., Int J Cancer, 2008; De Wever et al., Semin Cancer Biol., 2014). Paracrine interactions between CAFs, also termed myofibroblasts, and cancer cells stimulate invasion of colon cancer cells in matrix scaffolds. The pro-invasive activity was found also with the secretome and we identified the combined action of Scatter Factor/Hepatocyte Growth Factor (SF/HGF) and tenascin-C (TNC) to promote invasion (De Wever et al., FASEBJ, 2004). Secretome proteomics revealed the presence of multiple other pro-metastatic proteins suggesting that the molecular characteristics of a CAF remain in evolution (De Boeck et al., Proteomics, 2013). CAFs show operational flexibility; eg their ability to respond dynamically to a cancer cell’s fluctuating demands by shifting profitable signals necessary in metastasis. Local, tissue-resident fibroblasts and mesenchymal stem cells (MSCs) coming from reservoir sites such as bone marrow (BM) are the main progenitor cells of CAFs (De Boeck et al., Oral Oncol, 2010). A successful invader must survive in an ectopic environment and CAFs provide advantageous signals to cancer cells to accomplish survival through AKT activation. Neuregulin (NRG)-1 secreted by CAFs increase cancer cell number through HER2/HER3-dependent activation of the PI3K/AKT pathway. Translational data demonstrate transmembrane NRG-1 expression in CAF in primary colorectal cancer and in liver metastasis, with the strongest expression in the immediate vicinity of HER2/HER3 expressing cancer cells. Moreover, high transmembrane NRG-1 expression is a poor prognosis marker in colorectal cancer (De Boeck et al., GUT, 2013). The odds that an aggressive cancer cell will form a metastatic colony in some organ are vanishingly small. Nevertheless, metastasis is responsible for more than 90% of cancer-associated mortality; thus the clinical need to prevent or target metastasis is high. Viewing cancer within the context of ecosystems may provide opportunities to exploit CAFs to create tumor-environment bio-mimetics to deceive and redirect metastatic cancer cells.

A different view on sodium balance.

Textbook theory holds that extracellular fluids readily equilibrate, electrolyte concentrations in the extracellular fluid compartments are constant, and the kidney is solely responsible for controlling the body sodium content. Investigation of salt and water balance traditionally relies on short-term studies of bodily responses to extremes in salt intake. Ultra-long-term sodium balance studies instead studied the kidney's response to constant salt intake. The studies suggest that steady-state sodium balance in humans is characterized by storage and release of sodium from the body. The absence of accompanying changes in the body fluid matrix indicates the presence of metabolically relevant sodium reservoir sites in the body. In rats and mice, sodium is stored in skeletal muscle and skin. Homeostatic immune cells control reservoir electrolyte metabolism via the lymphatics. Failure of this extrarenal clearance process results in skin electrolyte accumulation and arterial hypertension. Noninvasive detection of sodium reservoir metabolism in patients by NaMRi methodology allows rapid transfer into the clinical arena. Body sodium content in humans and animals is not constant, does not always readily equilibrate with water, and is not exclusively controlled by the kidneys. This different view provides with new research avenues for basic and clinical investigators.

Woodland and Caddo Period Sites at Toledo Bend Reservoir, Northwest Louisiana and East Texas

Toledo Bend Reservoir is one of the largest artificial lakes in the United States and the largest reservoir in the South. The lake is approximately 65 miles long and contains over 1200 miles of shoreline in both Louisiana and Texas. Construction began in 1964 with completion of the power plant, with the subsequent filling of the lake in 1969. Archaeological investigations at Toledo Bend Reservoir on the Sabine River and tributaries in both Louisiana and Texas took place primarily took during the 1960s, with survey and excavations, sometimes of a very limited nature by the University of Texas (UT) and Southern Methodist University (SMU). Girard has continued archaeological investigations along the Louisiana side of the reservoir, however, focusing particularly on work at the James Pace site. In this article we review the nature of the material culture assemblage of the Woodland and Caddo sites at Toledo Bend Reservoir based on the collections at the Texas Archeological Research Laboratory at The University of Texas at Austin (TARL). This consists of ceramic and/or lithic artifacts from 76 different sites in Louisiana and Texas. We have also examined ceramic vessels from Woodland and Caddo burial features at several Toledo Bend Reservoir sites. Our purpose in re-examining the TARL collections from the Toledo Bend Reservoir is to better understand and characterize the material culture assemblages (primarily decorated ceramic sherds) from sites that date between ca. 2500 years B.P. and the late 17th-early 18th century A.D., particularly in light of questions concerning the cultural affiliation and cultural taxonomic relationships of the ancestral Caddo sites in this part of East Texas and western Louisiana.

Bacterial community composition and function along a river to reservoir transition

Bacteria in reservoir systems are controlled by a variety of factors. In this study, a lacustrine system with high primary production fed by a river with lower algal biomass was used to examine the relationship between bacterial community composition (BCC) and function under varying environmental conditions. Bacterial abundance, respiration, production, and growth efficiency were measured in the Cuyahoga River and Lake Rockwell reservoir in Ohio (USA). BCC was determined via terminal restriction length polymorphisms of 16S rRNA genes. Also, in laboratory experiments, bacterial communities were exposed to algal exudates and leaf leachates. Concurrently with physicochemical differences between lacustrine and riverine sites, there were differences in BCC that seemed unrelated to environmental conditions and DOC sources (color: chlorophyll a ratio). Functional attributes varied among dates but not sites, except for bacterial heterotrophic productivity. Overall, the source of DOC differed between the river and reservoir as did BCC. In contrast, bacterial functions, with the exception of productivity, were similar between the river and reservoir sites. Environmental variables (e.g., temperature, nutrient, and chlorophyll a) were correlated with differences in bacterial function. Differences in BCC did not coincide with functional differences in the field or controlled laboratory conditions suggesting that structure and function were uncoupled.

Aquifer storage wellfield assessment and design through benefit-cost-sensitivity analysis

Abstract Benefit-Cost Analysis (BCA) of reservoirs is standard practice, though with much room for improvement, especially through creative and expanded, but still focused use of sensitivity analysis. The significant and growing scarcity of feasible reservoir sites and groundwater substitutes has led to greater interest in projects that would complement reservoirs and, at the margin, provide a substitute for increased reservoir capacity. An Aquifer Storage and Recovery (ASR) wellfield is one such possible complement-substitute for base-load reservoir capacity. It uses aquifer storage capacity to save wet-year allocations for the driest years, which reduces or avoids price increases and/or administrative curtailment of some water uses. So, the objectives of the article are threefold: (a) to provide an initial examination of the general economics of ASR wellfields; (b) to provide an example; and (c) to demonstrate proposed improvements in BCA methodology.

Seasonal distribution of potentially pathogenic Acanthamoeba species from drinking water reservoirs in Taiwan.

In order to detect the presence/absence of Acanthamoeba along with geographical variations, water quality variations and seasonal change of Acanthamoeba in Taiwan was investigated by 18S ribosomal RNA (rRNA) gene TaqMan quantitative real-time PCR. Samples were collected quarterly at 19 drinking water reservoir sites from November 2012 to August 2013. Acanthamoeba was detected in 39.5 % (30/76) of the water sample, and the detection rate was 63.2 % (12/19) from samples collected in autumn. The average concentration of Acanthamoeba was 3.59 × 10(4) copies/L. For geographic distribution, the detection rate for Acanthamoeba at the northern region was higher than the central and southern regions in all seasons. Results of Spearman rank test revealed that heterotrophic plate count (HPC) had a negative correlation (R = -0.502), while dissolved oxygen (DO) had a positive correlation (R = 0.463) in summer. Significant differences were found only between the presence/absence of Acanthamoeba and HPC in summer (Mann-Whitney U test, P < 0.05). T2 and T4 genotypes of Acanthamoeba were identified, and T4 was the most commonly identified Acanthamoeba genotypes. The presence of Acanthamoeba in reservoirs presented a potential public health threat and should be further examined.

Lessons from a Volvocacean jackpot

:Mud collections made from a small reservoir in southern China while pursuing a rare Volvocacean, Platydorina caudata, produced an unusual wealth of other Volvocaceae but no Platydorina. Nine different Volvocacean lineages were obtained, identified by morphology, physiological traits, and nuclear rRNA transcribed spacer sequence comparisons. They probably represented progeny of zygotes formed upstream and washed into the inlet of the reservoir. Similar reservoir sites have increased in abundance in recent years worldwide, which invites further collecting.

Petroleum system modeling and risk assessments of Ad’daimah oil field: a case study from Mesan Governorate, south Iraq

Oil biomarkers and isotope values of the analyzed samples from the Sa’adi and Yamama Formation reservoirs of Santonian and Valanginian ages, respectively, from well Da-1 as well as Yamama Formation extracts are plotted on sterane triangle, hopane diagram, tricyclic terpane diagram, pristane to phytane ratio with canonian variables, δ13C saturate, aromatics, and pristine-phytane diagrams and have indicated a source environment and lithology of marine algal type II that are nonbiodegraded and deposited in anoxic environments of carbonate and shale. Source maturation at the time of the oil generation is assessed by plots of oil, and the analyzed values of the Yamama source rocks on the pristine-phytane diagram indicate these to be mature with Tmax equivalent of 435 °C based on plots of methyldibenzothiophene ratio (MDR) and vitrinite reflectance of Ro = 0.70–0.85 based on methylphenothrene ratio (MPI). Source age assessment is taken from δ13C (%) and the calculated C28/C29 sterane ratio indicates early Lower Cretaceous age. The Yamama Formation in this study showed excellent hydrocarbon potential with extracted organic matter of up to 16,674 ppm with a total organic carbon (TOC) equivalent of 16.64 wt%. Correlation of the analyzed data from Ad’daimah field with other oil fields in the Mesan Governorate indicates the same characteristics and revealed this to be clustered in one place in all the diagrams, but the source age shows two oil families where the first is sourced from Upper Jurassic-Lower Cretaceous as in the case in the Ad’daimah field while the second is sourced from Middle and Upper Jurassic as in the case in the Halfaya field. Source-oil correlation is confirmed in this study by plots of values from the analysis of Sa’adi and Yamama oil of well Da-1 with the extracts from the Yamama-Sulaiy formations in isotopic δ13C saturate and aromatics, calculated C28/C29 sterane ratio diagram, sterane triangle, and MPI versus Ro. These showed grouping of the oil and extracts of the analyzed data into one place of depositional environment, maturation, and age characteristics that indicate a very good correlation with excellent hydrocarbon generation from the Yamama Formation that measures up to 16,674 ppm of extracted organic matter. PetroMod software basin modeling has confirmed hydrocarbon generation from the Yamama Formation under burial thermal temperature of 114–120 °C with 285–300 mg HC/g TOC for 95 % hydrocarbon transformation from the disseminated organic matters with critical point of hydrocarbon migration and accumulation at 10 million years ago. Palynomorphs have indicated ages of Valanginan-Berriassian for the Yamama Formation and Tithonian-Berriassian for the Sulaiy Formation. Marking places of source rocks and oil reservoir on seismic section across well Da-1 for the Jurassic and Cretaceous strata have shown model assessments of the hydrocarbon generation places of the Yamama Formation, migration pathways and accumulation site, as well as places of enriched oil to assess reservoir sites and suggest for risk assessments of drilling sites for hydrocarbon production from the Yamama and Sa’adi formations. On the other hand, seismic sections in Halfaya and Buzargan fields showed hydrocarbon migration from the Sargelu Formation.

Reservoir Alternate Surgical Implantation Technique: Preliminary Outcomes of Initial PROPPER Study of Low Profile or Spherical Reservoir Implantation in Submuscular Location or Traditional Prevesical Space

Alternative reservoir site placement has become an accepted technique for patients who require an inflatable penile prosthesis. To our knowledge there has been no prospective evaluation of this technique, which is currently off label. We performed a prospective, multicenter, multinational, internal review board approved study to evaluate the effectiveness and safety of alternative reservoir site placement. PROPPER initiated in June 2011, is a database containing patient outcomes of inflatable penile prosthesis implantation. Patients with AMS® penile prostheses continue to be enrolled at 13 North American sites. We examined PROPPER study data to determine surgical implantation use patterns for the AMS 700™ series. We evaluated reservoir implantation site and complications by implantation site. A total of 759 patients had been implanted with an AMS 700 series implant by the time of evaluation. Mean patient followup was 17.8 months (range 0 to 36). There was no reported case of revision surgery for a palpable reservoir and no report of vascular or hollow viscous injury associated with alternative reservoir site placement. Two cases of reservoir herniation in the alternative reservoir site placement group and 2 in the space of Retzius group were treated with reservoir reimplantation. Patients with 1-year assessment available were satisfied or very satisfied with the device and reported a frequency of use of more than once per month. Alternative reservoir placement in the submuscular location is an option in patients who undergo inflatable penile prosthesis surgery. Implant surgeons should consider alternative reservoir site placement a safe, effective alternative to reservoir placement in the space of Retzius.

Microbial quality and phylogenetic diversity of fresh rainwater and tropical freshwater reservoir.

The impact of rainwater on the microbial quality of a tropical freshwater reservoir through atmospheric wet deposition of microorganisms was studied for the first time. Reservoir water samples were collected at four different sampling points and rainwater samples were collected in the immediate vicinity of the reservoir sites for a period of four months (January to April, 2012) during the Northeast monsoon period. Microbial quality of all fresh rainwater and reservoir water samples was assessed based on the counts for the microbial indicators: Escherichia coli (E. coli), total coliforms, and Enterococci along with total heterotrophic plate counts (HPC). The taxonomic richness and phylogenetic relationship of the freshwater reservoir with those of the fresh rainwater were also assessed using 16 S rRNA gene clone library construction. The levels of E. coli were found to be in the range of 0 CFU/100 mL – 75 CFU/100 mL for the rainwater, and were 10–94 CFU/100 mL for the reservoir water. The sampling sites that were influenced by highway traffic emissions showed the maximum counts for all the bacterial indicators assessed. There was no significant increase in the bacterial abundances observed in the reservoir water immediately following rainfall. However, the composite fresh rainwater and reservoir water samples exhibited broad phylogenetic diversity, including sequences representing Betaproteobacteria, Alphaproteobacteria, Gammaproteobacteria, Actinobacteria, Lentisphaerae and Bacteriodetes. Members of the Betaproteobacteria group were the most dominant in both fresh rainwater and reservoir water, followed by Alphaproteobacteria, Sphingobacteria, Actinobacteria and Gammaproteobacteria.

Managing flow, sediment, and hydropower regimes in the Sre Pok, Se San, and Se Kong Rivers of the Mekong basin

AbstractThe Lancang/Mekong River Basin is presently undergoing a period of rapid hydropower development. In its natural undeveloped state, the river transports about 160 million metric tons of sediment per year, maintaining the geomorphologic features of the basin, sustaining habitats, and transporting the nutrients that support ecosystem productivity. Despite the importance of sediment in the river, currently little attention is being paid to reservoir sediment trapping. This study is devoted to assessing the potential for managing sediment and its impact on energy production in the Se San, Sre Pok, and Se Kong tributaries of the Mekong River. These tributaries drain a set of adjacent watersheds that are important with respect to biodiversity and ecological productivity, and serve as a significant source of flow and sediment to the mainstream Mekong River. A daily sediment transport model is used to assess tradeoffs among energy production and sediment and flow regime alteration in multiple reservoir systems. This study finds that eventually about 40%–80% of the annual suspended sediment load may be trapped in reservoirs. Clearly, these reservoirs will affect the rivers' sediment regimes. However, even after 100 years of simulated sedimentation, reservoir storage capacities and hydropower production at most reservoir sites are not significantly reduced. This suggests that the strongest motivation for implementing measures to reduce trapped sediment is their impact not on hydropower production but on fish migration and survival and on sediment‐dependent ecosystems such as the Vietnam Delta and Cambodia's Tonle Sap Lake.

Spatio-temporal variability of seismic noise above a geothermal reservoir

Abstract We report on the application of seismic noise investigations, including H/V (horizontal to vertical) spectral ratio and array techniques, to a shallow gas-rich geothermal reservoir in Heybeli, southwestern Turkey. Fundamental resonant frequencies were determined to estimate the sediment thickness. Using small-scale seismic arrays, phase velocity dispersion curves were derived by correlating noise recordings according to the extended spatial autocorrelation method. Improved shear wave velocity profiles were estimated by combining Rayleigh wave dispersion curves and horizontal to vertical spectral ratios in a joint inversion. We found that the velocities obtained for the reservoir site are higher than those for a location outside the reservoir. In addition to the fundamental resonant peaks in the spectra, a clear 6-Hz-signal could be identified originating from the center of the geothermal field, repeatedly observed in 2010 and 2011. It had been claimed that low frequency (1–10 Hz) seismic signal anomalies were correlated with the occurrence of hydrocarbons. One of the physical mechanisms under consideration to explain these tremor-like signals above such reservoirs is resonant amplification due to the oscillation of bubbles. Based on the signal similarity with volcanic tremors, it is not a priori given that the liquid phase must be oil for resonance effects to occur. We therefore applied array techniques to identify potential noise originating from the Heybeli reservoir. In fact, the frequency–wavenumber ( f – k ) method clearly indicated a noise source coming from the main production well of the reservoir. In 2011, as part of our assessment, the operators of the spa facility stopped the extraction of thermal water for 2 h: the 6-Hz-signal disappeared after the pump had been stopped and reappeared after the pump began operating again. Thus, the 6-Hz-signal is likely of artificial origin. In addition, no natural noise source inside the reservoir could be identified.

A Metal Sorption/Desorption Study to Assess the Potential Efficiency of a Tailings Dam at the Golgohar Iron Ore Mine, Iran

The Golgohar Iron Ore Mine in southern Iran is a large open pit that operates below the groundwater table; until now, its tailings have been disposed of without proper environmental safeguards. A tailings dam, constructed with environmental standards, has been proposed to address this problem. So, it was important to assess the effect of the solid and liquid wastes on the sorption/desorption behavior of the soil of the site to evaluate the risk of release of metal contaminants to groundwater after dam construction. Soil samples from a proposed tailings dam reservoir site and dried solid waste from the present tailings dump were collected for analysis to assess the potential effects of solid and liquid wastes on the sorption/desorption behavior of the soil and the risk of resultant groundwater contamination after dam construction. Laboratory batch and sorption isotherm tests along with a pilot-scale field experiment were conducted to study the sorption potential of the soil. Analysis showed that concentrations of Co, Ni, Cu, As, Sr, and Mn in the soils were already significantly elevated. The experiments indicated that although the soil of the area has some potential to adsorb contaminants such as Co, Ni, Cu, and As, other elements, such as Sr and Mn will be more mobile. Given the soil’s limited sorption capacity, these contaminants will all likely enter the groundwater eventually, and so the probable transmission of these elements into the lower depths must be considered in the design of the proposed dam.