The objective of this study was to assess the potential role of aquatic biofilms as natural reservoirs for Blastocystis. For this purpose, surface water (n = 4) and biofilm samples (n = 8) were collected from a stream nearby an urban area characterized by limited sanitation infrastructure and a high prevalence of Blastocystis in humans. Blastocystis cysts were detected in three of the four water samples and seven of the eight biofilm samples using fluorescence microscopy. Furthermore, viable cysts were identified exclusively in biofilm samples (five of the eight), while no live cysts were detected in water samples. These findings indicate that aquatic biofilms provide a habitat where Blastocystis cysts can adhere and remain viable, potentially contributing to their environmental accumulation. In addition, molecular characterization of the five isolates identified subtypes ST8 (allele 21) and ST3 (allele 36). This study is the first to report the detection and identification of viable Blastocystis subtypes in aquatic biofilms. The analysis of biofilms by fluorescence microscopy, as demonstrated here, offers a promising approach for monitoring Blastocystis and could serve as an alternative to traditional water sampling methods.

Stunting, a manifestation of chronic malnutrition, is widespread in India. This, coupled with biased preferences of parents towards their eldest sons, has led to stunting and underweight among girls that grows sharply with increasing birth order. We study the impact of an environmental water pollutant on child growth outcomes in arsenic contaminated regions of India. Using a large, nationally representative household survey and exploiting variation in soil textures across districts as an instrument for arsenic, we find that arsenic exposure beyond the safe threshold level is negatively associated with height-for-age and weight-for-age. Negative effects are larger for girls who are born at higher birth orders relative to the eldest. This, we argue, suggests that the lack of adequate nutrition and health care during early childhood can make girls more vulnerable to external environmental hazards due to their lower immunity and underdeveloped bodies.

Cystic and alveolar echinococcosis are considered the second and third most significant foodborne parasitic diseases worldwide. The microscopic eggs excreted in the feces of the definitive host are the only source of contamination for intermediate and dead-end hosts, including humans. However, estimating the respective contribution of the environment, fomites, animals or food in the transmission of Echinococcus eggs is still challenging. Echinococcus granulosus and E. multilocularis seem to have a similar survival capacity regarding temperature under laboratory conditions. In addition, field experiments have reported that the eggs can survive several weeks to years outdoors, with confirmation of the relative susceptibility of Echinococcus eggs to desiccation. Bad weather (such as rain and wind), invertebrates and birds help scatter Echinococcus eggs in the environment and may thus impact human exposure. Contamination of food and the environment by taeniid eggs has been the subject of renewed interest in the past decade. Various matrices from endemic regions have been found to be contaminated by Echinococcus eggs. These include water, soil, vegetables and berries, with heterogeneous rates highlighting the need to acquire more robust data so as to obtain an accurate assessment of the risk of human infection. In this context, it is essential to use efficient methods of detection and to develop methods for evaluating the viability of eggs in the environment and food.

Opus signinum is a lime mortar mix that includes crushed pottery as an aggregate. Because it is water-resistant, it was used to line hydraulic structures like pools and aqueducts. While there have been numerous recreations of Roman ‘concretes’ in the past, hydrophobic linings have received little attention, and all preliminary studies in these recreations have paid more attention to the dry components and the lime than to the hydric needs of the mortar. The experiment presented here was to gain a better understanding, with the help of traditional builders, of the process of mixing and applying hydrophobic linings and calculate the water consumption of individual samples. The data obtained contribute to assessing the water consumption needs on Roman construction sites, what associated logistics these volumes required, and what the technicalities of applying this specific type of lining were.

The identification and quantification of the water associated with powdered clinoptilolite and clinoptilolite-bearing tuffs were made using thermogravimetric, vacuum gravimetric, and differential scanning calorimetric techniques. Inflection points on thermogravimetric curves at approximately 80° and 170°C correspond to changes in the proportions of externally adsorbed water to loosely bound zeolitic water and loosely bound zeolitic water to tightly bound zeolitic water, respectively. These three types of water can be differentiated by temperatures and heats of dehydration obtained from differential scanning calorimetry. These temperatures and heats of hydration are 75 ± 10°C and 59.2 ± 5.9 kJ/mole H2O, 171 ± 2°C and 58.7 ± 6.1 kJ/mole H2O, and 271 ± 4°C and 78.7 ± 7.0 kJ/mole H2O for external water, loosely bound water, and tightly bound water, respectively. The ratio of loosely bound zeolitic water to tightly bound zeolitic water determined in this study is similar to that reported in the literature from structural determinations, indicating that the desorption properties of clinoptilolite are determined by the specific positions of the water molecules in the structure.

The integral thermodynamic quantities of adsorbed water on Na- and Ca-montmorillonite have been calculated from water adsorption isotherms on Na- and Ca-montmorillonite at 298° and 313°K and from one adsorption isotherm and calorimetric measurements at 298°K. The integral entropy values decrease and then increase as the amount of adsorbed water approaches zero. In both systems, the curves approach the entropy value of free liquid water at the high content water. The thermodynamics of adsorbate on a non-inert adsorbent is discussed in some detail. The two-isotherm method gives the energy change of the water phase only, whereas the colorimetric method gives the energy change of the whole system (clay, exchangeable cations, and the adsorbed water). Only when the energy changes in the solid phase are negligible (=inert surface) should the two methods give similar results. An hypothesis was developed to explain the entropy-change data of water adsorbed on clay surfaces, in which the clay surface behaves as a non-inert adsorbent.

The diffusion of water in Li-montmorillonite was studied by incoherent quasielastic neutron scattering. Experiments were carried out on sedimented samples equilibrated at relative humidities of 32%, 58%, and 98%, corresponding approximately to 1, 2, and 3 molecular layers of water in the clay. At all three humidities, although the mobility of the water molecules is less than in bulk water, all water molecules in the system undergo translational diffusion, at least over short distances (>5 Å), with correlation times shorter than 5 × 10−11 sec.

Various models of molecular motion have been used to account for the exact shape of the scattering. The only completely successful model is one where a water molecule undergoes jump-translational diffusion and rotational diffusion. The mean square jump length is 10–15 Å2 with a residence time between jumps of 4–2 × 10−11 sec. The translational diffusion coefficient increases with humidity, having values of 4, 7, and 10 × 10−10 m2/sec for the three humidities. These values can be combined with values previously obtained by tracer measurements to give an estimate of 0.75–0.8 for the tortuosity factor. Although the samples are anisotropic, there is no clear evidence that the diffusion of water over distances 5–20 Å is anisotropic. An upper limit of 3 can be deduced for the rate of diffusion parallel to the direction perpendicular to the platelets.

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 (<50 μm) laumontite and gypsum. Macrocrystalline (>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.

The influence of the activity of water on the phase composition of aluminum hydroxides obtained by reaction of amalgamated aluminum with water has been studied. The reaction was carried out in solutions of water and dioxane, and in sodium chloride solutions of different concentrations; amorphous aluminum hydroxide was precipitated initially. The aging of this primary product to bayerite, pseudoboehmite, or an amorphous gel was controlled by the water content of the system. The pseudoboehmite has shown a significant reactivity when used as a source of alumina in the hydrothermal syntheses of kaolinite at relatively low temperature and pressure.

The basal spacings of montmorillonites with Li, Na, K, Cs, Mg, Ca, Sr, Ba, and Pb interlayer cations were measured after immersion in dimethylsulfoxide (DMSO) and in water-DMSO mixtures. In DMSO alone, the spacings were in the range 18.3–19.3 Å and fell on or near a single curve when plotted against ionic field strength, q/r2, where q = valence and r = ionic radius. These spacings correspond to double layers of DMSO molecules between the silicate layers. Water had practically no effect on the spacings when the mole fraction of DMSO exceeded about 35–45%. Osmotic swelling of Li-, Na-, and K-mont-morillonite occurred up to mole percentages of DMSO 45%, 30%, and 10%, respectively. K- and Cs-mont-morillonite formed single-layer complexes in appropriate water-DMSO mixtures with spacings of 14.3 Å prior to development of double-layer complexes when the mole fraction of DMSO exceeded 35% and 15%, respectively.

The frequency, v, for O-D stretching in D2O films between the superimposed layers of different micas and montmorillonites was measured at several film thicknesses and temperatures of 2° and 25°C by infrared spectroscopy. The molar absorptivity, ε, for O-D stretching in HDO films between the montmorillonite layers was also measured at different film thicknesses and 25°C. It was found that v is related to mw/mm, the mass ratio of D2O to mica or montmorillonite, by the equation v = v0 exp β/(mwmm where v0 is the O-D stretching frequency in pure D2O and ß is a constant. Since mw/mm is proportional to a, the area under the absorption peak, mw/mm can be replaced by a in this equation. It was also found that ε decreased dramatically as the thickness of the water film between the montmorillonite layers decreased. These results were interpreted to mean that the structure of the interlayer water is perturbed by the interlayer cations and/or silicate surfaces.