Brine Accumulation Research Articles

Impacts of Desalination Brine Discharge on Benthic Ecosystems.

Seawater reverse osmosis (SWRO) desalination facilities produce freshwater and, at the same time, discharge hypersaline brine that often includes various chemical additives such as antiscalants and coagulants. This dense brine can sink to the sea bottom and creep over the seabed, reaching up to 5 km from the discharge point. Previous reviews have discussed the effects of SWRO desalination brine on various marine ecosystems, yet little attention has been paid to the impacts on benthic habitats. This review comprehensibly discusses the effects of SWRO brine discharge on marine benthic fauna and flora. We review previous studies that indicated a suite of impacts by SWRO brine on benthic organisms, including bacteria, seagrasses, polychaetes, and corals. The effects within the discharge mixing zones range from impaired activities and morphological deformations to changes in the community composition. Recent modeling work demonstrated that brine could spread over the seabed, beyond the mixing zone, for up to several tens of kilometers and impair nutrient fluxes from the sediment to the water column. We also provide a possible perspective on brine's impact on the biogeochemical process within the mixing zone subsurface. Desalination brine can infiltrate into the sandy bottom around the discharge area due to gravity currents. Accumulation of brine and associated chemical additives, such as polyphosphonate-based antiscalants and ferric-based coagulants in the porewater, may change the redox zones and, hence, impact biogeochemical processes in sediments. With the demand for drinking water escalating worldwide, the volumes of brine discharge are predicted to triple during the current century. Future efforts should focus on the development and operation of viable technologies to minimize the volumes of brine discharged into marine environments, along with a change to environmentally friendly additives. However, the application of these technologies should be partly subsidized by governmental stakeholders to safeguard coastal ecosystems around desalination facilities.

Modelling and simulation of brinicle formation.

Below the Arctic sea ice, under the right conditions, a flux of icy brine flows down into the sea. The icy brine has a much lower fusion point and is denser than normal seawater. As a result, it sinks while freezing everything around it, forming an ice channel called a brinicle (also known as ice stalactite). In this paper, we develop a mathematical model for this phenomenon, assuming cylindrical symmetry. The fluid is considered to be viscous and quasi-stationary. The heat and salt transport are weakly coupled to the fluid motion and are modelled with the corresponding conservation equations, accounting for diffusive and convective effects. Finite-element discretization is employed to solve the coupled system of partial differential equations. We find that the model can capture the general behaviour of the physical system and generate brinicle-like structures while also recovering dendrite composition, which is a physically expected feature aligned with previous experimental results. This represents, to our knowledge, the first complete model proposed that captures the global structure of the physical phenomenon even though it has some discrepancies, such as brine accumulation.

Prospects for the industrial development of the stocks of the Artemia parthenogenetica Barigozzi, 1974 (Branchiopoda, Anostraca) cysts in the Kara-Bogaz-Gol Bay (the Caspian sea)

The Kara-Bogaz-Gol Bay has a high natural potential for cysts of the brine shrimp Artemia parthenogenetica, which can be used in various areas of the national economy. Commercial fishing of the Artemia population of Kara-Bogaz- Gol Bay began in the mid-1990s. As a result, a new potential of the bioresource of cysts on the international market was discovered. Since 2000, there has been a sharp decline in the breeding stock of the Artemia population in the Kara-Bogaz- Gol Bay. By 2002, commercial fishing of Artemia cysts in Kara-Bogaz-Gol Bay was stopped, due to the fact that the brine shrimp population was in a depressed. The main reason was the increase in the salinity of the Kara-Bogaz-Gol Bay due to the accumulation of brine in the strait connecting the Caspian Sea with bay, which prevented the flow of Caspian water into the bay, in volumes sufficient to maintain the salt balance in the Kara-Bogaz-Gol Bay at the optimal level for the development of the Artemia population. Since 2020, there has been a decrease in the level of the Kara-Bogaz-Gol Bay, which continues at the present time. Satellite data show that there are minor accumulations of algae and Artemia cysts in the bay. Minor accumulations of brine shrimp cysts in the bay can be used as a starting potential necessary for inoculation work, after resolving the issue of maintaining the salt balance in the reservoir at a level sufficient for the development of the nutrition of Artemia and its reproduction in natural conditions. To revive the Artemia cysts fishery, a set of measures aimed at improving the hydrological and ecological regimes of the bay has been proposed.

A Mississippi Valley–type Zn-Pb mineralizing system in South China constrained by in situ U-Pb dating of carbonates and barite and in situ S-Sr-Pb isotopes

AbstractThe ages of Zn-Pb deposits are exceptionally challenging to determine owing to the lack of suitable mineral chronometers and techniques. Here we present the first result for in situ LA-ICP-MS U-Pb dating of carbonates and barite from a Mississippi Valley– type (MVT) Zn-Pb deposit in South China. Hydrothermal dolomite in close textural and paragenetic association with Zn-Pb sulfides, and calcite and barite cement from the breccia ores, yield ages of 473.4 ± 2.7 Ma and 368.7 ± 3.1 Ma, respectively. Together with new in situ S-Pb-Sr isotope values, these data reveal an epigenetic Zn-Pb mineralization history, agreeing well with a model involving basinal brine accumulation and MVT Zn-Pb sulfide precipitation. Because carbonate is a common mineral in Zn-Pb deposits worldwide, and other minerals in such deposits suitable for isotope dating are generally absent, in situ U-Pb dating of gangue carbonates opens a new window for better defining the ore genesis of this globally important Zn-Pb deposit type and for tracking hydrothermal fluid flow in sedimentary basins.

Studies of periodic seawater spray icing with unilateral NMR

Sea water ice has a complicated pore structure consisting of brine-filled pockets within a solid ice matrix. In this work, an unilateral Nuclear Magnetic Resonance instrument was used to characterize the evolution of sea-ice brine inclusions in two types of ice: stationary seawater ice and seawater spray ice formed by periodic spraying on horizontal and vertical surfaces. The portable unilateral NMR was capable of measuring very low amounts of brine (<10% of the water-filled volume). CPMG experiments were performed to extract the information on brine content and T2 distribution at temperatures between −6 °C and −16 °C. 1D imaging was used to spatially resolve the ice brine accumulation. The results show that the seawater spray ice growth, brine content (greater for the horizontal orientation than for the vertical one), and T2 distribution (unimodal for stationary ice and bimodal for spray ice) depend on temperature and surface orientation.

Seasonal Evolution of Cape Darnley Bottom Water Revealed by Mooring Measurements

This study examines the seasonal evolution of Cape Darnley Bottom Water (CDBW), using the results of mooring and hydrographic measurements in the slope region off Cape Darnley in 2008–2009 and 2013–2014. Newly formed CDBW began reaching the western and nearshore part of the slope region off Cape Darnley in April, spread to the offshore and eastern part in May, and reached the easternmost part in September. The potential temperature and salinity decreased and the neutral density increased when newly formed CDBW reached mooring sites. Potential temperature-salinity properties of CDBW changed over time and location. The salinity of the source water of CDBW estimated from potential temperature-salinity diagrams started to increase at a nearshore mooring in late April, which is about 2 months after the onset of sea-ice production, and continued to increase during the ice production season. It is most probable that the accumulation of brine in the Cape Darnley polynya produces the seasonal variation of potential temperature-salinity properties of CDBW. Two types of CDBW were identified. Cold and less saline CDBW and warm and saline CDBW were present in Wild and Daly Canyons, respectively. This indicates that the salinity of the source water of CDBW increased in the westward direction. CDBW exhibited short-term variability induced by baroclinic instability.

Migration, Crystallization and Dissolution Changes of Salt Solution with Color Rendering Property in Porous Quartz Materials.

In order to visually display the migration and crystallization process of salt solution in porous cultural relics, copper sulfate solution with color rendering property was selected to record the migration, crystallization and resolution of salt solution in simulated SiO2 samples under different environmental conditions in real time through high-resolution recording system, scanning electron microscope system, salt phase X-ray diffraction system, and so on. The results showed the migration of salt solution in porous samples was related to the structural characteristics of the porous samples, the migration rate of salt solution, the evaporation rate and the change frequency of crystallization–resolution, etc., in which the large pore size of the sample, the higher the concentration and the faster migration and evaporation rate of salt solution, the greater the change rate of the brine accumulation zone or salt crystallization zone in the different porous samples. During the humidification–drying cycles of rainfall, the higher the cycle frequency of humidification–drying was, the higher the drying temperature was, the more frequent the crystallization-analysis change of salt in the salt-bearing sample was, and the more extensive the distribution of salt crystal zone was. This is the first time to visualize the salt belt by simulating the changing process of a salt solution with a color rendering property in porous samples. This has scientific theoretical guidance for the study of the migration–crystallization changes of soluble salts contained in porous silicate cultural relics. The visibility analysis results of multilayer salt crystal belts can also provide the preliminary basis for further effective desalination of salt bearing cultural relics.

Role of River Runoff and Sea Ice Brine Rejection in Controlling Stratification Throughout Winter in Southeast Hudson Bay

The Hudson Bay system is undergoing climate-driven changes in sea ice and freshwater inflow and has seen an increase in winter river inflow since the 1960s due in part to flow regulation for hydropower production. Southeast Hudson Bay and adjacent James Bay are at the forefront of these changes, with more than 1-month shortening of the season of sea ice cover as defined using satellite data, increases in winter inflow from the regulated La Grande River complex, and changes in coastal ice and polynya behavior described by Belcher Islands’ Inuit. In summer, there is a fresh coastal domain in southeast Hudson Bay fueled by river runoff and sea ice melt. To investigate winter oceanographic conditions and potential interactions between runoff and ice melt or brine in southeast Hudson Bay, we initiated the first winter study of the shallow waters surrounding the Belchers, collecting conductivity-temperature-depth (CTD) profiles and conductivity-temperature (CT) time series using under-ice moorings, and collecting water samples and ice cores during four campaigns between January 2014 and March 2015. Tandem measurements of salinity and δ18O were made for the water and ice samples to discriminate between freshwater sources (river runoff and sea ice melt). We find that southeast Hudson Bay, and particularly the nearshore domain southeast of the Belchers, is distinguished in winter by the presence of river water and strong surface stratification, which runs counter to expectations for a system in which local freshwater remains frozen on land until spring freshet (May–June) and sea ice growth is adding brine to surface waters. The amount of river water around the Belcher Islands increased significantly from fall through to late winter according to δ18O records of ice. The accumulation of river water in surface waters during the winter is directly associated with an accumulation of brine, which considerably exceeds the capacity of local ice formation to produce brine. We therefore infer that brine is advected into the study area together with river water, and that interplay between these properties establishes and maintains the level of surface stratification throughout winter. With reference to a NEMO ocean model simulation of winter circulation in the study area, we propose a conceptual model in which winter river inflow into James Bay drives the northward transport of both river water and brine captured near the surface, with reductions in brine-driven deep convection in the area’s flaw leads. While past changes in winter oceanographic conditions and sea ice cannot be reconstructed from the few available scientific data, the presence of significant runoff in winter in southeast Hudson Bay implies heightened sensitivity to delayed freeze-up under a warmer climate, which will have the effect of reducing brine early in the winter, also promoting increased stratification and river plume transport.

Ore genesis of Kongxigou and Nanmushu Zn-Pb deposits hosted in Neoproterozoic carbonates, Yangtze Block, SW China: Constraints from sulfide chemistry, fluid inclusions, and in situ S-Pb isotope analyses

The recently discovered Kongxigou and Nanmushu Zn-Pb deposits are hosted in the Neoproterozoic Dengying Formation carbonates in the Mayuan district of Shaanxi Province, SW China, the northern margin of Yangtze Block. The deposits show a three-period mineralization history: (1) pre-ore sedimentary and diagenetic, (2) main-ore hydrothermal mineralization (stages I, II, and III), and (3) post-ore supergene. Multiple sulfide generations are distinguished, including two generations for sphalerite, e.g., Sp(a) from the stage I and Sp(b) from the stage II; and three generations for pyrite, e.g., Py(s) from the diagenetic period, Py(a) from the stage I and Py(b) from the stage II. The sedimentary and diagenetic period of the Kongxigou and Nanmushu deposits are characterized by Py(s) with high positive δ34S values (+16.2 to +19.9‰). The hydrothermal Zn-Pb sulfide precipitation stages are characterized by positive δ34S values (+11.4 to +23.9‰) that were likely caused by thermochemical sulfate reduction (TSR) of seawater or evaporitic sourced sulfates. In situ δ34S characteristics from the hydrothermal stage I to stage II record different sulfur sources. The ore-forming fluids show features of moderate-high temperature (137 °C–329 °C), high salinity (can reach up to 27.7 wt% NaCl + CaCl2 equivalent) with a Na-Ca- (Mg) -Cl dominant composition, hydrocarbon-rich (e.g., CH4 and bitumen), which are interpreted as basin brines. In situ lead isotope analyses of hydrothermal stage sulfides show 208Pb/204Pb, 207Pb/204Pb, and 206Pb/204Pb ratios of 37.865–37.979, 15.635–15.661 and 17.885–18.101, respectively, which suggest a mixing of lead from the basement and the host rocks. We suggest the ore genesis of Kongxigou and Nanmushu deposits differs from the typical MVT Zn-Pb deposit models, and propose a new mixing model of basin brine accumulation and Zn-Pb sulfide precipitation in the hydrothermal stages.

Numerical simulation of formation of a concentrated brine lens subject to magma chamber degassing

The mathematical model of flow of a binary salt-water mixture through a porous medium in a wide range of pressure and temperature is developed taking different multiphase thermodynamic equilibria of the mixture into account. Formation of concentrated brine lenses above a degassing magma chamber is investigated within the framework of the model. The lenses are assumed to be coupled with generation of ore deposits. It is shown that the lens formation is caused by phase transitions of two different types undergoing at different depths in the magmatic fluid rising towards the surface. In the shallow zones salt precipitation on the skeleton of the porous medium in the form of a solid phase leads to clogging of pore space and reduction of the permeability. As a result, the magmatic fluid flow towards the surface is blocked and this facilitates the concentrated brine accumulation in a local zone.

Regional groundwater flow and accumulation of a massive evaporite deposit at the margin of the Chilean Altiplano

AbstractFocused groundwater discharge in closed basins provides opportunities to investigate mechanisms for closing hydrologic and solute budgets in arid regions. The Salar de Atacama (SdA), adjacent to the Central Andean Plateau in the hyperarid Atacama Desert, provides an extreme example of halite (&gt;1800 km3) and lithium brine (~5000 ppm) accumulation spanning late Miocene to present. Minimum long‐term water discharge needed to sustain halite accumulation over this timescale at SdA is 9–20 times greater than modern recharge (and double wet‐climate paleorecharge) within the topographic watershed. Closing this imbalance requires sourcing water from recharge on the orogenic plateau in an area over 4 times larger than the topographic watershed. Prolonged water discharge at SdA requires long residence times, deep water tables in recharge zones coupled with persistent near‐surface water tables in discharge areas, and large contributing areas characterized by strong gradients in landscape and climate resulting from plateau uplift.

Numerical simulation of surface-downhole geoelectrical measurements in order to detect brine plumes

A large amount of hydrocarbon reservoirs in the world are in the secondary recovery stage and improving this step in the exploitation of these reservoirs would greatly benefit the oil industry. Secondary recovery involves injecting brine in some wells in order to maintain reservoir pressure. The injected water moves mainly through the channels with higher permeability of the reservoir rock. The identification of these channels would allow the development of technical strategies to close them. In this context, the ability to detect brine flow pathways after injection is a goal of this work. Given the high electrical conductivity of brine, the use of geoelectrical methods can be useful to detect and monitor flow evolution. The limitations in the application of this method are due to the characteristics of the target: a very conductive fluid is usually contained in paths with dimensions that are much smaller than the depth at which it is located. Therefore, our objective is to overcome these constraints in order to find the strategies required to successfully detect and eventually monitor the movement of brine flowing from injection wells.In this work, we studied the feasibility of detecting brine in an oil reservoir with surface-downhole electrical measurements. To achieve this, we designed an electrical model of the reservoir from well data and numerically simulated the forward geoelectrical response to determine the conditions under which the anomaly, i.e., the accumulation of brine, can be identified. Our results show that once the initial location of the brine is known, by installing potential electrodes in a single well the direction of brine migration can be determined, even in unfavorable conditions with relatively few surface measurements. In the case of a well equipped with permanent electrodes, this could be an efficient method to monitor the evolution of the brine plume.

The role of climate in the accumulation of lithium-rich brine in the Central Andes

Lithium-rich brine within the sub-surface of the Salar del Hombre Muerto (SHM) salt pan in the Andes of northwestern Argentina has a chemical and isotopic composition which is consistent with Li derived from several sources: the modern halite saturated lagoon, Li-rich salts and brines formed recently, and dissolution of halite which precipitated from ancient saline lakes. SHM lies in the closed basin that includes part of the massive Cerro Galán caldera which is drained by the Río los Patos, which is responsible for 90% of surface runoff into the salar. The low Li isotope composition, +3.4‰, of this river is consistent with significant contributions of geothermal spring water. As water drains through the volcaniclastic deposits which cover a large proportion of the basin, Li removal, as indicated by decreasing Li/Na, occurs but without significant isotope fractionation. This indicates a mechanism of surface sorption onto smectite or ferrihydrite rather than Li incorporation into octahedral structural sites of clays. These observations suggest that conditions in this high altitude desert have limited the dilution of hydrothermal spring water as well as the formation of clay minerals, which jointly have allowed the Li resource to accumulate rapidly. Changes in climate on a multi-millennial time scale, specifically in the hydrologic budget, have resulted in solute accumulation rates that have been variable through time, and decoupled Li and Na fluxes. Inflow to the salar under modern conditions has high Li/Na (7.9×10−3 by wt) with δ7Li indistinguishable from basement rocks (−0.3‰ to +6.4‰), while under pluvial climate conditions the Li/Na of the saline lake was 40 times lower than the modern lagoon (0.1–0.3×10−3 compared to 10.6–13.4×10−3) with slightly higher δ7Li, +6.9‰ to +12.3‰, reflecting the uptake of 6Li into secondary minerals which formed under a wetter climate.

Detection of brine plumes in an oil reservoir using the geoelectric method

During water injection in a reservoir at the secondary recovery phase, oil is replaced by salt water, producing different saturation zones in the formation containing this reservoir. This process could be optimized if the direction of the fluids is monitored. Since there are large contrasts in the electric conductivity between salt water and oil, geoelectrical methods could provide a water saturation map at any given moment of the production. The case we study here corresponds to a rather shallow reservoir (between 500 and 600 m in depth). As the wells are in production, electrodes for borehole measurements cannot be introduced. Hence, our objectives are to determine the possibilities of detecting the channelling direction of saline water between injection and producing wells, and applying the method of placing electrodes on the surface or even burying them, but at depths corresponding to shallow layers. We design an electrical model of the reservoir and then numerically simulate the geoelectrical response in order to determine the conditions under which the anomaly, i.e. the accumulation of brine in a reduced area, can be detected. We find that the channelling of the brine can be detected for the reservoir studied here if the electrodes are placed at 180 m depth. The Wenner configuration using 16 electrodes provides the best resolution. Therefore, monitoring the voltage at a number of electrodes embedded at rather shallow depths (from a technical-logistic point of view) could give information about the direction of the saline channelling even if a quantitative image of the subsoil cannot be obtained due to the reduced number of electrodes used in the study.

Distributions of runoff, sea-ice melt and brine using δ 18O and salinity data — A new view on freshwater cycling in Hudson Bay

Distributions of sea-ice melt (SIM) and runoff (RW) were determined in Hudson Bay (Canada) using salinity and oxygen isotope (δ 18O) tracers. In late summer/early fall, stations throughout the Bay exhibited a summer surface mixed layer (SSML) 30–60 m deep, which contained the seasonal freshwater inputs. The SSML overlies a cold subsurface water, extending up to 125 m deep in the water column, indicative of the previous winter's surface mixed layer (WSML). Our data show that most of the RW remains in a nearshore coastal regime in summer, with limited exchange into the interior of the Bay. At depth, brine (negative SIM) accumulation is closely associated with excess RW, implying that deep water formation occurs when sufficient brine is rejected from the growing ice to overcome RW buoyancy in surface water. The inventory of RW at depths below the WSML is equivalent to almost one year's runoff inputs which, given a residence time of deep water of 4–14 years, implies that 6–16% of the annual river discharge is shunted into deeper waters each winter. The balance between the RW buoyancy in surface waters and densification due to ice formation appears to control where and when deep-water formation can occur. Although not directly measured, regions forming deep water are likely small (< 10% of the Bay area) and associated with flaw leads extending around the perimeter of the landfast ice edge in the Bay. The processes evident in δ 18O and salinity data must be incorporated into ocean models to obtain a realistic view of freshwater cycling and its sensitivity to climate perturbations.

Origin of halite brine in the Onondaga Trough near Syracuse, New York State, USA: modeling geochemistry and variable-density flow

Halite brine (saturation ranging from 45 to 80%) lies within glacial sediments that fill the Onondaga Trough, a bedrock valley deepened by Pleistocene glaciation near Syracuse, New York State, USA. The most concentrated brine occupies the northern end of the trough, about 10 km downgradient of the northern limit of halite beds in the Silurian Salina Group, the assumed source of salt. The chemical composition of the brine and its radiocarbon age suggest that the brine originally formed about 16,700 years ago through dissolution of halite by glacial melt water and later mixed with saline bedrock water. Two hypotheses regarding the formation of the brine pool were tested through variable-density flow simulations using SEAWAT. Simulation results supported the first hypothesis that the brine pool was derived from a source in the glacial sediments and then migrated to its current position, where it has persisted for over 16,000 years. A second hypothesis that the brine pool formed through steady accumulation of brine from upward flow of a source in the underlying bedrock was not supported by simulation results, because the simulated age distribution was much younger than the age estimated from geochemical modeling.

Minerogenic Theory of the Superlarge Lop Nur Potash Deposit, Xinjiang, China

Abstract Located in the eastern part of the Tarim basin, Xinjiang, the Lop Nur was an ultimate water catchment area of the Tarim basin during the Quaternary. Through nearly ten years of investigation and research, the authors have found a superlarge brine potash deposit in the Luobei subbasin—a secondary basin of the Lop Nur depression. The deposit has been mined now. On that basis, the authors propose new theories on the genesis of the potash rock deposit. In the tectonic and geomorphologic contexts, the Tarim basin lies in a “high mountain‐deep basin” environment. At the beginning of the Quaternary, influenced by the neotectonic movement, the Lop Nur evolved into a “deep basin” in the Tarim basin. At the end of the middle Pleistocene, neotectonic migration began to take place in the interior of the Lop Nur and a new secondary deep basin—the Luobei subbasin—formed gradually. Despite its small area, it is actually the deepest subbasin in the Lop Nur depression, where brines of the Lop Nur Salt Lake gather and evaporate, thus providing materials for the formation of a superlarge brine potash rock deposit. With respect to the phenomenon of brine concentration and change with deepening of the lake, the authors propose a model of “high mountain‐deep basin” tectonic migration for potash concentration. In the sedimentological context, the honeycomb‐shaped voids developed in glauberite rock in the subbasin are good space for potash‐rich brine accumulation. Study indicates that the deposition of glauberite requires recharge of calcium‐rich water. In the Tarim area the calcium‐rich water might come from deep formation water or oilfield water, and the river water recharging the Lop Nur Salt Lake was rich in sulfate radicals and other components; in addition, the climate in the area was very dry and the brine evaporated steadily, thus resulting in deposition of substantial amount of glauberite, potash accumulation in intercrystal brine and final formation of the potash deposit. Generally, potash formation in a salt lake undergoes a three‐stage process of “carbonates→sulfates (gypsum and glauberite)→chlorides (halite etc.)”, but in the study area there only occurred a two‐stage process of “carbonates→sulfates (gypsum and glauberite)”. The authors call this new geological phenomenon the “two‐stage potash formation” model. In conclusion, the superlarge Lop Nur potash deposit is the result of combined “high mountain‐deep basin” tectonism and “two‐stage potash formation”.

Mine failure associated with a pressurized brine horizon; Retsof salt mine, western New York

Abstract The eventual loss of the Retsof Salt Mine from flooding was initiated on March 12, 1994 with a magnitude 3.6 earthquake, the collapse of a small-pillar panel, an initial inrush of brine and gas to the mine and a sustained inflow of fresh water. An examination of closure data for two mine panels involved in the inflow suggested an anomalous buildup of fluid pressure above the panels in the period leading up to their collapse. The initial brine and gas inflow immediately following the collapse coincided with the apparent relief of the excess pressure. The potential existence of a pre-collapse, pressurized, brine and gas pool above the panels was investigated through an analysis of nineteenth century solution mining data, a review of recent salt mine data, and an interpretation of geologic and geophysical data from post-collapse investigations. Published reports from the nineteenth century reveal that natural brine and gas pools existed in the region prior to mining. Correlation of gamma ray logs with geologic logs from contemporary drill holes and core holes provided a mechanism for interpreting the distribution of those natural brine pools. Our investigation indicated that natural gas and brine pools existed within Unit D of the Syracuse Formation approximately 160 ft above the mining horizon. Such brine accumulation apparently formed from the circulation of meteoric water through vertical discontinuities that were connected to overlying fresh water aquifers long before mining began in the valley in the late nineteenth century.

Passive microwave remote sensing of thin sea ice using principal component analysis

Time sequences of surface based measurements of passive microwave emission from growing saline ice reported by Wensnahan et al. (1993) are used to explore the possibility of developing a satellite based sea ice concentration algorithm which solves for the presence of thinner ice. It is shown that two classes of thinner ice can be distinguished from mixtures of open water (OW), first‐year (FY) ice, and multiyear (MY) ice. The two classes do not necessarily correspond to specific World Meteorological Organization ice types; rather, newly formed ice represents a brief transition spectrum between OW and thin ice. Newly formed ice appears to be optically thick at 37 and 90 GHz and has a relatively dry surface. The thin ice spectrum occurs when the ice is greater than 4 cm thick and appears to result from the accumulation of brine at the surface of the ice. Thin ice has a relatively stable spectrum characterized by high brightness temperatures, a near‐zero spectral gradient at vertical polarization, and a large difference between vertical and horizontal polarizations. Supervised principal component analysis (PCA) was done of laboratory data using 10 channels of passive data: vertical and horizontal polarization at 6.7, 10, 19, 37, and 90 GHz. Analyses were also done on subsets of the laboratory data at 6.7 to 37 GHz as well as 19 to 90 GHz, representing the scanning multichannel microwave radiometer (SMMR) and special sensor microwave imager (SSM/I) satellite frequencies, respectively. Using all of the channels or the SMMR subset makes it possible to solve for mixtures of OW and FY, MY, newly formed and thin ice but with large errors. However, any four of these scene types can be distinguished with reasonable accuracy. The SSM/I frequencies allow determination of at most four of these scene types but with moderate errors. PCA was used in a case study of SSM/I data from the Bering Sea for April 2, 1988. Winds from the north formed thin ice areas which the NASA Team algorithm interprets as large amounts of OW and MY ice. With PCA, these same areas are interpreted as 20–30% OW near the lee shores but otherwise as consisting almost entirely of thin ice. We conclude that thin ice can be detected using satellite data. However, questions remain as to how the thin ice spectrum varies with environmental conditions, how it evolves to that of FY, and how this evolution affects the predicted concentrations of thin ice.

Fluid reservoir (?) beneath the KTB drillbit indicated by seismic shear‐wave observations

Indications for the possible presence of a fluid accumulation below the drillbit of the KTB (German Continental Deep Drilling Project)‐Hauptbohrung are provided by comparisons of seismic P‐wave and S‐wave reflection sections. A bright reflection with negative polarity at approx. 8 km depth is seen only on P‐wave sections. It is absent on S‐wave sections in contrast to deeper reflections. This observation can be explained by the following geological models or combinations of them: (1) brine accumulation within a strongly fractured rock reservoir, (2) liquid/gas interface within strongly fractured rocks, (3) rock composition with increased quartz content and corresponding low Poisson's ratio, and (4) varying symmetry system of seismic anisotropy due to rock foliation. Predictions concerning the nature and location of this reflector are expected to be verified by drilling and direct probing in spring‐summer, 1993.