Number Of Water Particles Research Articles

Release of hazardous nanoplastic contaminants due to microplastics fragmentation under shear stress forces

The presence of nanoplastics in water has become a major environmental concern in the last decade however the knowledge on the origin and formation of these emerging contaminants is lacking due to analytical challenges in detection and quantification techniques. The release of nanoplastics due to the fragmentation of microplastics extracted from a facial scrub and the resulting toxicity on aquatic species are reported here for the first time. The daily use of 4 g of facial scrub could release up to 1011 microplastics of 400 nm in size per litre of wastewater from household drains. Turbulences created by mixing or pumping induced the fragmentation of microplastics into nanoplastics smaller than 10 nm via a crack propagation and failure mechanism, increasing the number of particles in water by one order of magnitude. Compared to microplastics at a fixed concentration number of 6.8 × 108 part./mL, the generated nanoplastics initiated the death of 54% more cells in zebrafish by passive ingestion via skin diffusion which therefore pose a real threat for aquatic living organisms. These results stress the need to reduce the release of nano/microplastics in the aquatic environment to prevent the contamination of all trophic levels.

An experimental study on the bulk precipitation mechanism of physical water treatment for the mitigation of mineral fouling

The present study investigated the mechanism of physical water treatment (PWT) using particle count analyses of water. The PWT method utilized in the present study included catalytic devices and low-voltage–high-frequency device through which water continuously recirculated. Concentrated hard water at electrical conductivity of 2300–2700 μS/cm was circulated in the study at two different flow rates (i.e., 500 l/h and 800 l/h) at the room temperature. After 66 h of operation for each test, the total number of particles in water for the PWT cases increased by 165–540% as compared with those for the no-treatment cases, depending on the flow rate used. The present particle counting results provided a support for the bulk precipitation hypothesis as the mechanism of PWT, which is essentially an electro-flocculation process.

Probabilistic Calculations of Groundwater Travel Time in Heterogeneous Three-Dimensional Porous Media

ABSTRACTGroundwater travel time (GWTT) estimation at a potential high-level waste (HLW) repository is subject to various technical uncertainties. These uncertainties stem from model and data uncertainties and cannot be resolved with field tests because of the long time (> 1,000 yr) and large space (> 5,000 m) scales involved. Therefore, computational methods for demonstrating and determining compliance with the GWTT rule will be used. Stochastic theory based approaches constitute a natural framework for performing GWTT estimations under conditions of uncertain and/or limited data.This study employs the generation of spatially correlated hydraulic conductivity fields by the Nearest Neighbor Model (NNM). Repeated (Monte Carlo) realizations of the statistically equivalent random fields are obtained, and the saturated steady-state groundwater flow equation is solved. These results are then used to estimate GWTT along particular paths by releasing a large number of water particles at various starting points. By doing so, path variability is sampled through the realization ensemble space and also through the independent particle “flights” within a specific flow field realization. The uncertainty in predicted GWTT due to parameter variability is assessed for a data set characteristic of the saturated zone at Yucca Mountain at three levels of parameter heterogeneity. However, since several parameters and the boundary conditions of the problem have been arbitrarily assumed, direct conclusions regarding the proposed Yucca Mountain site cannot be drawn from this study.

XX.—On the Particles in Fogs and Clouds

In May 1891 I communicated a paper to this Society “On a Method of Observing and Counting the Number of Water Particles in a Fog,” and in July of the same year a paper “On the Solid and Liquid Particles in Clouds.” One conclusion to which the observations contained in these papers pointed was, that there existed a relation between the thickness or density in clouds and fogs and the number of water particles present. Though the figures did not show that this relation was very close, yet in all the fogs and clouds tested there was a rough relation between the thickness of the air and the number of water particles observed.

On the Particles in Fogs and Clouds

At the beginning of the paper some observations made on the water particles in clouds on the Rigi on the 21st of May last are described. Previous observations with the fog-particle counter had shown that there is a relation between the density of a cloud and the number of water particles observed. On the occasion above referred to the number was very much greater than corresponded with the density. It is pointed out that the number of dust particles in the air which become centres of condensation depends on the rate at which the condensation is taking place, quick condensation causing a large number of particles to become active, slow condensation causing a small number; and that after the condensation has ceased a process of differentiation takes place, the larger particles, robbing the smaller ones of their water, owing to the vapour-pressure at the surface of drops of large curvature being less than at the surface of drops of smaller curvature. The particles in a cloud are by this process reduced in number, those remaining becoming larger and falling quicker, the cloud thus tending to become thinner by the reduction of the number of particles and by the falling of some of them. It is shown that the exceptional readings above referred to, obtained on the Rigi, were owing to the observations then made being taken in a new and rapidly-formed cloud, due to the strong wind blowing at the time causing a quick ascent and rapid cooling and condensation, the result being the formation of a large number of very small water particles. Though the number was very great, the particles were so small they were only just visible with great care with the magnifying power used in the instrument. Previous observations on cloud particles had been made in slowly-formed or in old clouds after the process of differentiation had been in play for some time, and after the drops had been reduced in number and increased in size.

On a Method of Observing and Counting the Number of Water Particles in a Fog

The phenomena known as haze, fog, mist, and rain are in a general way but the successive development of the same process, and the line which divides the one from the other is very indefinite. Dust in the atmosphere produces a haze, and the thickness of a haze of this kind depends principally on the amount of dust present when the relative humidity of the atmosphere is very low. But as the humidity increases the effect of the vapour increases also; the dust particles attract the water vapour which becomes deposited on them, thus increasing their size and their hazing effect, till at last when the air is nearly saturated it becomes very thick, and forms what we call a fog; when in this condition, the thickness of the atmosphere depends principally on the degree of saturation. Between the haze and the fog, however, there is no recognised distinction in kind, it is principally one of degree. After the air is saturated and the conditions are such as to tend to cause supersaturation, then a change takes place in the condensation. A few of the dust particles have water deposited on them, and after a time they grow and become little drops of water, in which the original dust nucleus bears a very small proportion to the total weight. At this stage it is still called a fog, but after more water is deposited on the small drops they grow and become what is known as mist, and when the mist drops combine and fall they are called rain-drops.