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This article explores how lack of cross-cultural understanding led to disappointing results in the early stages of an agricultural revitalization project focused on the cultivation of Theobroma cacao—a native plant traditionally cultivated among the indigenous Kuna People of San Blas, Panama. Interviews with elders revealed insights into the cultural dimensions of cacao and aspects of project design that failed to address the role of cultural context, locus of control, and value orientation. Communication failures between project technicians and local people represent important considerations for future development projects linking indigenous livelihoods and biodiversity conservation. Deeper consideration of local customs and values may enable conservation objectives to be achieved in ways that are locally inspired and relevant.

High alkalinity values found in some formation waters from Kettleman North Dome oil field are due chiefly to acetate and propionate ions, with some contribution from higher molecular weight organic acid ions. Some of these waters contain no detectable bicarbonate alkalinity. For waters such as these, high supersaturation with respect to calcite will be incorrectly indicated by thermodynamic calculations based upon carbonate concentrations inferred from traditional alkalinity measurements

Highly-alkaline (pH > 12.5) meteoric waters of a Ca2+OH−-type issue from naturally calcined bituminous marl. The cold (16.5 ≤ T(°C) ≤ 19.1) waters are super-saturated with minerals thought to be of high-temperature origin.

Analyses have been made of gases in clouds apparently emanating from Mount St. Helens. Despite appearances, most of the water in these clouds does not issue from the volcano. Even directly above a large fumarole δD and δ 18O data indicate that only half the water can come from the volcano. Isotopic and chemical evidence also shows the steam in the volcano (−33.0 per mol δD) from which a condensate of 0.2 N HCI was obtained is not a major cause of the explosions. The steam in the volcano is derived from a metamorphic brine in the underlying Tertiary meta andesite. The gas that caused the explosive eruptions is carbon dioxide.

Low-temperature (120°C and less) metamorphism of graywacke, granite and andesite yields zeolites and precursor gels by reaction with fresh water but low-greenschist facies by reaction with salt (sea)water.

Previous studies of the Calera limestone (Permanente terrane, Franciscan complex) of California have shown that deposition occurred at approximately 25°N paleolatitude atop an oceanic plateau or rise, and that it was subsequently transported northeast and accreted to the North American continental margin in the early Tertiary. The Permanente terrane in the study area along the Pacific coast south of San Francisco contains a suite of rock types present in north dipping imbricate thrust slices possibly related to the subduction and accretion of an oceanic crustal sequence. Geochemical studies of greenstones, thought to represent fragments of the dismembered oceanic crust, indicate affinities with mid-ocean ridge basalts and within-plate basalt. These greenstones may represent fragments of the rise upon which the Calera limestone was deposited. Metamorphic minerals in the greenstones indicate both sea-floor metamorphism and locally, high-pressure, low-temperature metamorphism. It is concluded tentatively that the entire Permanente terrane in the study area underwent high-pressure, low-temperature metamorphism but that temporal or geologic conditions prevented widespread recrystallization or development of blueschist facies minerals. Structures in the deformed rocks can be related to underthrusting beneath the continental margin and attachment to the overriding plate. Studies of veins indicate several stages of dewatering. It is likely that dewatering was a major process in the attachment event, as shown by veins associated with this phase of deformation. Structurally interleaved melanges and broken formation contain sedimentary rock clearly derived from a continental margin; these rocks probably represent trench and trench slope facies that were underthrust with the accreting oceanic crustal sequence.

Carbon dioxide is the propellant gas in volcanic eruptions and is also found in mantle xenoliths. It is speculated that CO 2 occurs as a free gas phase in the mantle because there is no reason to expect CO 2 to be so universally associated with volcanic rocks unless the CO 2 comes from the same source as the volcanic rocks and their xenoliths. If correct, the presence of a free gas in the mantle would lead to physical instability, with excess gas pressure providing the cause of both buoyancy of volcanic melts and seismicity in volcanic regions. Convection in the mantle and episodic volcanic eruptions are likely necessary consequences. This suggestion has considerable implications for those responsible for providing warnings of impending disasters resulting from volcanic eruptions and earthquakes in volcanic regions.

Well-crystallized laumontite has been found for the first time precipitating naturally at the earth’s surface at temperatures of 89° to 43°C as a component of gray to white coatings and efflorescences on exterior surface and as precipitates on interior fractures of stones and blocks lining Hot Springs Creek immediately downstream from Sespe Hot Springs, Ventura County, California. X-ray powder diffraction, scanning electron microscope (SEM), and electron microprobe analyses show thenardite to be the dominant phase in the exterior coatings, in association with minor microcrystalline ( 1 mm) laumontite is the dominant phase in interior fracture coatings and is associated with quartz, potassium feldspar, and gypsum. Trace amounts of smectite(?), halite, a mercury sulfide, an iron sulfide, an iron-bearing mineral (possibly an oxide or carbonate), and a copper mineral are also present. Zeolites other than laumontite have not been seen, and carbonate minerals are either entirely or nearly absent. SEM textures indicate nonreactive intergrowths of laumontite, quartz, potassium feldspar, and gypsum. Unbroken laumontite crystals are generally euhedral or have skeletal growth characteristics and exhibit sharp, fresh, non-corroded faces, edges, and corners. The water issuing from the hottest and largest spring is 89°C, has a pH of 7.74, 1200 mg/liter total dissolved solids, and contains Na+, Cl−, SO42-, and H4SiO4 as the dominant dissolved species. Computations indicate that the water is supersaturated with respect to laumontite, quartz, chlorite, and prehnite and is slightly undersaturated with respect to calcite and noncrystalline silica. Water-dominated water-rock interaction is indicated by isotopic analyses. The δO18 composition expectable on the basis of the −81‰ δD composition is −11.38‰ instead of the −9.5‰ actually found (all referred to SMOW). The water chemistry suggests that the subsurface water source may have a temperature of 125°–135°C. This temperature range, together with the regionally low geothermal gradient, implies that the source is probably 3550 to 3900 m beneath the springs in fractured and permeable Mesozoic and older plutonites and gneisses. The discovery of laumontite crystallizing at atmospheric pressure and 43°C (or lower) provides important insight into the processes responsible for burial diagenetic laumontite and a valuable perspective on the zeolite metamorphic facies.

Fluids related to Serpentinization are of at least three types. The first reported (Barnes and O'Neil, 1969) is a fluid of local meteoric origin, the chemical and thermodynamic properties of which are entirely controlled by olivine, orthopyroxene, brucite, and serpentine reactions. It is a Ca+2-OH−1 type and is shown experimentally to be capable of reacting with albite to yield calcium hydroxy silicates. Rodingites may form where the Ca+2-OH−1 type waters flow across the ultramafic contact and react with siliceous country rock.

Two calcium-magnesium carbonate solid solutions form Holocene travertines and conglomerate cements in fresh water stream channels of the Coast Range of California. Calcite does not yield the {015} diffraction maximum. The {006} diffraction maximum is lacking over most of the range of composition of calcite. Calcite has compositions from CaCO3 to Ca0.5Mg0.5CO3. Dolomite yields both the {006} and {015} diffraction maxima over its entire composition range, Ca0.6Mg0.4CO3 to Ca0.5Mg0.5CO3. The Ca-Mg carbonates form in isotopic equilibrium and thermodynamic disequilibrium from dispersion of Ca2+-rich water into CO32−-rich water within the alluvium. The stable isotope data suggest that all the Mg-rich carbonates are primary precipitates and not a result of Mg-substitution in precursor CaCO3. There is a correlation between δC13 and Mg content of the carbonates which predicts a 5%. fractionation of C13 between dolomite and calcite at sedimentary temperatures. C14 is incorporated in Ca-Mg carbonates forming from C13-poor meteoric waters and C13-rich waters from Cretaceous sediments. C14 ages of the Ca-Mg carbonates are apparent, and cannot be corrected to absolute values. Solution rates of calcite decrease with increasing MgCO3 content; dolomite dissolves slower than any calcite.

All carbonates associated with the ultramafic rocks and serpentinites of the western United States are shown by their stable isotope ratios to be of near-surface, low-temperature origin. These include vein materials that have been previously classified as hydrothermal. New laboratory and natural data were obtained on the equilibrium isotope relations between hydromagnesite and water. The origins of travertines in the ultramafic area are easily distinguished on the basis of their stable isotope ratios. The extremely heavy isotope ratios of nesquehonites suggest an intricate evaporating-film mechanism of formation.

A small stream in eastern California was studied in detail to determine the causes of travertine deposition from the stream. Although the ground water feeding the stream is slightly supersaturated to just saturated with calcite, the ground water is supersaturated with CO2 with respect to the overlying air. The water becomes increasingly supersaturated with calcite in a downstream direction as CO2 loss to the air and by photosynthesis exceeds the rate of precipitation of calcite. Water loss by evaporation was below detection and does not play an important role in calcite deposition in this case. The water loss is by seepage through the stream bed. Observations showed variations in HCO−3, pH, discharge, Ca+2, relative humidity, water and air temperatures, and dissolved CO2. Comparisons of observed and equilibrium states are given for five sampling stations along the stream.

Field measurements of redox potential (Eh) and pH have been made on iron-rich (up to 35 p.p.m.) ground water of southern Maryland, and iron concentrations have been determined by laboratory analysis. The data obtained can be interpreted in terms of equilibrium being obtained between the ground waters and ferric minerals intermediate in properties between freshly precipitated ferric hydroxide and hematite. Apparently significant measurements of Eh and pH can be made, and thus two quasi-independent controls on iron concentrations and well-casing corrosion can be separated.

Natural liquid carbon dioxide is produced commercially from a 2.5-km-deep well near the 4,500-yr-old maar volcano, Mount Gambier, South Australia. The carbon dioxide has accumulated in a dome that is located on the extension of a linear chain of volcanic activity. A magmatic origin for the fluid is suggested by the geological setting, δ13CPDB of –4.0‰, for the CO2 (where PDB represents the carbon-isotope standard), and a relatively high 3He component of the contained helium and high 3He/C ratio (6.4 x 10−10). The 3He/4He and He/Ne ratios are 3.0 and > 1,370 times those of air, respectively. The CO2, as collected at the Earth's surface at 29.5 °C and 75 bar, expands more than 300-fold to form a gas at 1 atm and 22 °C. We suggest that liquid CO2 or high-density CO2 fluid (the critical point is 31.1 °C, 73.9 bar) of volcanic origin that expands explosively from shallow levels in the Earth's crust may be a major contributor to 'phreatic' volcanic eruptions and maar formation. Less violent release of magmatic CO2 into crater lakes may cause gas bursts with equally disastrous consequences such as occurred at Lake Nyos, Cameroon, in August 1986.

Waters unusually rich in ammonia, boron, carbon dioxide, hydrogen sulfide, and hydrocarbons are found in more than 100 localities along the Pacific coast of the United States. The waters are believed to be products of low-grade metamorphism of marine sediments. The marine sedimentary rocks would have to be tectonically emplaced below crystalline rocks in many places. Mercury ore deposits are probably also products of the low-grade metamorphism.

Ultrabasic (pH > 11) water issues from some fresh ultramafic bodies. The properties of the ultrabasic solutions are believed to be due to current reactions yielding serpentine from primary olivines and pyroxenes. The low concentrations of divalent airon. divalent magnesium, and dissolved silica from the serpentinization require an increase in rock volume.

Results of chemical and isotopic analyses of water and gases of twelve soda springs and two hot springs of Colorado are reported.

Carbon-dioxide discharges are concentrated along zones of seismicity such as the circum-Pacific belt and the alpine belt of southern Europe and Asia Minor. They commonly occur along young orogenic belts and are seldom found in either old orogenic belts or cratonal areas of continents except where the cratons are being fragmented. Submarine springs discharging C02 are known at only a few localities along oceanic crustal spreading centers, but these may indicate a highly common and widespread phenomenon. Geologic and isotopic data indicate that the C02 being discharged from these several tectonic settings is derived variously from (1) organic material, (2) metamorphism of marine carbonate rocks, and (3) the mantle. Production of C02 at depth may develop high pore pressure and thus facilitate slippage of faults. Rapid release of C02 may result in explosive activity.

Carbon dioxide discharges are concentrated along zones of seismicity such as the circum-Pacific belt and the alpine belt of southern Europe and Asia Minor. They commonly occur along young orogenic belts and are seldom found in either old orogenic belts or cratonal areas of continents except where the cratons are being fragmented. Submarine springs discharging CO/sub 2/ are known at only a few localities along oceanic crustal spreading centers, but these may indicate a highly common and widespread phenomenon. Geologic and isotopic data indicate that the CO/sub 2/ being discharged from these several tectonic settings is derived variously from (1) organic material, (2) metamorphism of marine carbonate rocks, and (3) the mantle. Production of CO/sub 2/ at depth may develop high pore pressure and thus facilitate slippage of faults. Rapid release of CO/sub 2/ may result in explosive activity.

Analyses were made for dissolved constituents including selenium (Se) in waters associated with subsurface agricultural drainage from the western San Joaquin Valley of California. In the vicinity of Kesterson National Wildlife Refuge and the Grassland wetlands area Se was found to be mobilized in water. As a consequence of this mobility and bioaccumulation in the aquatic food chain, Se occurred in waterfowl at levels toxic enough to cause deformities and deaths. Se concentrations in sumps that collect subsurface agricultural drainage water and inflows to drains sampled, ultimately leading into Kesterson national Wildlife Refuge and the Grassland, ranged from 84 to 4,200 microgram/L (ug/L) Se. Levels of Se were reduced in the San Luis Drain flowing into Kesterson National Wildlife Refute to approximately 300 ug/L Se and in three of the drains sampled flowing into the Grassland to approximately 50 ug/L Se. Serious effects on water fowl habitat were caused by both these levels. Se contents of algal mats and salt crusts from evaporation ponds of the San Luis Drain contained up to parts per million Se. Total ecosystem assessment of Se may be necessary for the evaluation of the toxicity of Se to the environment. No other trace element reportedmore » exceeded the various criteria for water at the level of magnitude of Se. 60 refs., 7 figs., 11 tabs.« less

Reinjection of formation waters creates few chemical problems if no large change in temperature has occurred, no gas or vapor has separated, access of air has been prevented, and the fluids have had an opportunity to react with the minerals to the point of compatibility. Injection of incompatible fluids may cause chemical problems. There is a need for prediction of fluid-mineral reactions. Most geochemists who have worked on mineral-fluid reactions have had inadequate data and have been reduced to assuming reaction states. The state most geochemists have assumed is one of equilibrium because it is uniquely defined and readily calculable. In an effort to test the applicability of an equilibrium model under real geologic conditions, real systems have been studied. Systems are chosen where reactions are known to occur and where the reactant minerals and fluids and product minerals and fluids can be identified and analyzed. Very seldom have stable equilibrium (minimum Gibbs free energy) conditions been found, although in some instances metastable equilibrium conditions have been found. The assumption of a stable equilibrium state is a very poor choice of model, especially a temperatures of 100°C and below. The general lack of attainment of equilibrium in no way impairs prediction of reactions, however. Admittedly there is no a prior thermodynamic method of predicting what phase will react, nor can the necessary departures from equilibrium be predicted before a reaction will occur at a significant rate, because thermodynamic arguments are time-independent. However, in geologic systems now accessible, enough reactions are occurring that, by observation, an empirical knowledge will provide a base for predicting reactions. The equations used for describing reactions states are [EQUATION] and [EQUATION] where ^DgrGR is the Gibbs free energy of the reaction R is the gas constant T is the temperature in degrees Kelvin Q is the reaction quotient K is the equilibrium constant n is the number of electrons in redox reactions F is the volt-gram equivalent Eheq is the Eh that would be measured if the reaction were at equilibrium Ehm is the measured Eh. ^DgrGR is the exact statement of the departure from equilibrium for the reaction of interest. Reactions should be studied in both reaction directions. Most reactions are asymmetric in that the ^DgrGR's required to dissolve most phases are of different values than the ^DgrGR's necessary to form the mineral from solution. The reactions should all be treated as congruent reactions. All the species in solution generated by complete solution of the solid must be considered. Using incongruent reactions introduces the unwarranted assumption of equilibrium. Some generalizations about the result can be made. Small, highly charged cations yield hydrous metastable phases (Fe(OH)3, amorphous silica) or a stable phase (Mg(Oh)2) at very slight supersaturations. Subsequent dehydration is very sluggish. Simple anhydrous carbonates require greater departures from equilibrium for precipitation to occur, but dissolve fairly readily. Simple anhydrous silicates dissolve with modest unsaturation but the anhydrous crystalline silicates require large supersaturations for precipitation. Sulfide minerals, although they may dissolve with oxidation of the sulfur to SO4-2, do not form except with enormous supersaturations. The problem is probably with the bisulfide ion. Siderite requires much less departure from eq ilibrium than pyrite for precipitation, yet both have Fe+2 as the cation. End_of_Article - Last_Page 2081

Seepage from rivers and irrigation canals has contributed to waterlogging and soil salinization problems in much of the Indus Plains of W. Pakistan. These problems are being overcome in part by tube-well dewatering and deep leaching of salinized soils. The ground waters described are anaerobic and some are supersaturated with troublesome minerals such as calcium carbonate (calcite) and iron carbonate (siderite). These waters are moderately corrosive to steel. Some wells contain sulfate-reducing bacteria, which catalyze corrosion, and pH-electrode potential relationships favorable to the solution of iron also are rather common. Corrosion is concentrated in the relatively active (anodic) saw slots of water-well screens, where metal loss is least tolerable. There appears to be no practicable preventive treatment for corrosion and encrustation in these wells. Even chemical sterilization for bacterial control has yielded poor results. Periodic rehabilitation by downhole blasting or by other effective mechanical or chemical cleaning methods will prolong well life. The most promising approach to future well-field development is to use filter pipes of epoxy-resin-bonded fiberglas, stainless steel, or other inert material which minimizes both corrosion and corrosion-catalyzed encrustation.

Reinjection of formation waters creates few chemical problems if no large change in temperature has occurred, no gas or vapor has separated, and access of air has been prevented. The fluids already have had an opportunity to react with the minerals to the point of compatibility. Injection of incompatible fluids, however, may cause chemical problems; thus, prediction of fluid-mineral reactions should be attempted. Real geologic systems chosen where reactions are known to occur, and where the reactant minerals and fluids and product minerals and fluids can be identified and analyzed, rarely have stable equilibrium (minimum Gibbs free energy) conditions. In some situations, metastable equilibrium conditions have been found. The assumption of a stable equilibrium state is an unwise assumption for a model, especially at temperatures of 100°C and below. The general lack of attainment of equilibrium in no way impairs prediction of reactions, however. Admittedly, there is no a priori thermodynamic method of predicting what phase will react, nor can the necessary departures from equilibrium (GR) be predicted before a reaction will occur at a significant rate, because thermodynamic arguments are time independent. However, in geologic systems now accessible, enough reactions are occurring that, by observation, an empirical knowledge will provide a base for predicting reactions. Reactions should be studied in both reaction directions. Most reactions are asymmetric in that the GR required to dissolve most phases is of different values than the GR necessary to form the mineral from solution. The reactions should all be treated as congruent. All the species in a solution generated by complete solution of the solid must be considered. Using incongruent reactions (reactions producing a new solid directly from the reactant solid) introduces the unwarranted assumption of equilibrium. In general, hydroxide species such as amorphous silica, limonite, and brucite, as well as simple carbonates, have been found to dissolve or precipitate in natural systems where GR values are 1 kcal or less. More complex silicates including serpentine, kenyaite, and magadiite may not precipitate from solutions where GR values favor supersaturation by as much as 7 kcal. Sulfides such as covellite, chalcocite, and pyrite may not precipitate even where supersaturation exceeds 30 kcal, although some sulfide minerals will dissolve readily where oxidation of sulfur can take place.

_________________________________________ _ Introduction ______________________________________ _ Field methods _____________________________________ _ Page B1 1 2 Results ___________________________________________ _ Summary and conclusions ___________________________ _ References ________________________________________ _

The partial pressure of carbon dioxide (Pco,), the degree of saturat'on with respect to calcite (/AP/^o.icite), the pH, and the concentrations of selected constituents in solution were determined for water from 52 wells and th* Platte River. Compared to the PCO.J in the atmosphere, the average Pco 2 in the ground water was many times greater and that in the river water was about twice as great. The high Pco2 in the ground water probably results from the absorption, by infiltrating precipitation, of carbon dioxide produced in the soil by respiration of plant roots and microorganisms. The values for IAP/Kcn c ite for the ground water ranged from 0.141 to 1.29 and for the river water the average was 9.6. Water from each of the 10 sampled wells on the terrace plain in southeastern Saunders County was unsaturated with respect to ealcite, whereas water from seven of the 42 wells on the Platte River flood plain was nearly saturated or supersaturated. Of the seven, two were in the Lincoln city well field where hydrologic relations indicate that a large fraction of the water yielded by the wells is induced seepage from the river. That more of the city wells did not yieH supersaturated water is surprising in view of the high /AP/£"c.icite values for the river water. Supersaturation of water from five of nine sampled well" downvalley from the well field probably is due to the presence of numerous limestone fragments in the Quaternary deposits in that part of the area. A Iso surprising was the finding that the average pH of the water from the ci^y wells was 1 unit lower than that of the river water. The presence of both dissolved iron and dissolved oxygen in the water from several of the city wells probably reflects derivation of the water from two distinct sources: ground water naturally in the aquifer and induced seepage from the river.

From information readily available in the literature, the compositions of mine waters are considered and possible reactions that yield such compositions are examined. Both matter balances and thermodynamic considerations indicate that reactions taking place in the mines probably do not involve significant amounts of dissolved oxygen. The reactions do, however, involve water and coexisting geologic materials (minerals and probably coal if present), which, in the absence of side reactions with carbonates, yield an acidic and strongly reduced solution. In the absence of active mine ventilation, mine water is an anaerobic solution. Major implications of the theoretical model bear on the treatment processes feasible for reducing the effect of acid mine water on surface-water resources.

Geochemical evidence for modern low-temperature serpentinization has been found in three new localities. Apparently the low-temperature reactions are a common mode of formation of the lizardite-chrysotile and brucite assemblage. Possibly the 18 O content of serpentine formed at low temperatures is in part inherited from the pyroxene and olivine.

CO2-rich springs occur worldwide along major zones of seismicity. They are mostly in young orogenic belts, but some are in areas of rifting continental platforms. Analyses of 13C content indicate that much of the CO2 is derived from the mantle and that other important sources are the metamorphism of marine carbonate-bearing sedimentary rocks and the degradation of organic material. The presence of calc-silicate minerals, such as pumpellyite in metagraywacke, is evidence of former conversion of carbonate-bearing rocks into calc-silicate minerals and release of CO2. The CO2 pressure in fractured rocks of a fault zone reduces the effective normal stress and, if it is sufficiently great, allows the fault to slip. If the pressure were maintained at a sufficiently high level, the fault behavior might be characterized by frequent small earthquakes and aseismic creep such as occur along active segments of the San Andreas system. The presence of CO2-rich springs may indicate a potentially hazardous seismic region. Monitoring of CO2 discharges could be useful in earthquake prediction.

Note: This paper is dedicated to Aaron and Elizabeth Waters on the occasion of Dr. Waters' retirement. Recent isotope studies show that the waters involved in a variety of geologic processes are dominantly the local meteoric water of each area. In most active geothermal systems, the D/H ratio of the hot water is nearly identical with the local cold meteoric water, but the O18/O16 ratio has been shifted to a more positive value because of subsurface exchange with rocks. The numerous thermal springs of the Wilbur Springs mercury district, although rich in CO2, are otherwise similar in Cl content and isotopic composition to analyzed California oil-field waters. Some of the springs discharge near the tops of ridges. These relations cannot be explained by normal meteoric recharge. Water of isotopic composition similar to that of Wilbur Springs occurs in the Sulphur Bank mercury district 15 mi west of Wilbur Springs, but the Sulphur Bank water is higher in B and NH3 and much lower in Cl than are the Wilbur and most oil-field waters. The Wilbur Springs and Sulphur Bank waters are enriched by ∼40‰ in δD and ∼13‰ in δO18 relative to local meteoric waters of each area, and thus require processes that differ, at least in part, from most previously studied geothermal systems. The D enrichment, chemical composition, and ridge-top discharge are best explained by large proportions of nonmeteoric water. Wilbur Springs and Sulphur Bank may be dominated, respectively, by waters of connate and metamorphic origin, derived from reaction of ancient ocean waters and marine sediments, and now being forced out by pressures that are higher than hydrostatic. Present data indicate that the most saline of each of these types is more restricted in range of δD than are present-day meteoric waters of the same areas; complete flushing by existing or ancient meteoric waters is unlikely. Many springs in the region are chemically intermediate between the high- and low-chloride types and commonly mix near the surface in different proportions with local meteoric water. Many of these springs are associated with mercury deposits and Alpine serpentinites.