Water environment

About: Water environment is a research topic. Over the lifetime, 13384 publications have been published within this topic receiving 125138 citations.

Proton magnetic resonance techniques for characterization of water in wood: application to white spruce

Abstract: Two new proton magnetic resonance techniques, relaxation spectra and relaxation selective imaging, have been used to investigate the distribution of water in samples of normal white spruce sapwood, heartwood, and juvenile wood as well as two rehydrated heartwood samples containing incipient decay and compression wood respectively. It is demonstrated that the spin-spin (T2) relaxation behavior in wood is best presented as a continuous spectrum of relaxation times. Spectra of T2 for white spruce show separate peaks corresponding to the different water environments. Bound water gives a peak with an T2 time of about 1 ms and lumen water gives a distribution of T2 times in the range of 10 to 100 ms. The lumen water T2 time is a function of the wood cell radius. Consequently, the different cell lumen radii distributions for spruce sapwood, juvenile wood, and compression wood are readily distinguishable by the shape of their T2 spectra. Water environments which are separable on a T2 spectrum may be imaged separately. Imaging has been carried out in one dimension for bound water and lumen water of a spruce sapwood sample at four different moisture contents ranging from 100% to 17%. For the first time, we demonstrate that above the fibre saturation point the moisture density profile of the bound water is largely independent of moisture content. The feasibility and utility of using these techniques for internal scanning of logs and lumber is discussed. These techniques should provide new insights into the wood drying process.

Systematic review and meta-analysis: association between water and sanitation environment and maternal mortality

Abstract: Objective To assess whether the lack of water or the lack of sanitation facilities in either the home or in health facilities is associated with an increased risk of maternal mortality and to quantify the effect sizes. Methods Systematic review of published literature in Medline, Embase, Popline and Africa Wide EBSCO 1980. Results Fourteen articles were found. Four of five ecological studies that considered sanitation found that poor sanitation was associated with higher maternal mortality. Meta-analysis of adjusted estimates in individual-level studies indicated that women in households with poor sanitation had 3.07 (95% CI 1.72–5.49) higher odds of maternal mortality. Four of six ecological studies assessing water environment found that poor water environment was associated with higher maternal mortality. The only individual-level study looking at the adjusted effect of water showed a significant association with maternal mortality (OR = 1.50, 95% CI 1.10–2.10). Two ecological and one facility-based study found an association between a combined measure of water and sanitation environment and maternal mortality. Conclusions There is evidence of association between sanitation and maternal mortality and between water and maternal mortality. Both associations are of substantial magnitude and are maintained after adjusting for confounders. However, these conclusions are based on a very small number of studies, few of which set out to examine sanitation or water as risk factors, and only some of which adjusted for potential confounders. Nevertheless, there are plausible pathways through which such associations may operate.

Isolation and identification of amoeba-resisting bacteria from water in human environment by using an Acanthamoeba polyphaga co-culture procedure.

Abstract: Amoeba-resisting bacteria (ARB) such as Legionella spp. are currently regarded as potential human pathogens living in the environment. To detect ARB from both human and environmental samples, co-culture with amoebae has been demonstrated as an efficient tool. However, using this procedure, mostly water from cooling towers and hospital water supplies have been investigated as the possible reservoir of ARB. In the present study, we studied ARB population in 77 environmental water samples including rivers, fountains, lakes and domestic wells in the south of France. As a result, a total of 244 isolates corresponding to 89 different species of ARB, but not Legionella spp., were identified. Ability to grow within and/or to be lytic for amoebae was revealed for the first time for several human pathogens. Six isolates are likely to be the members of a new or uncharacterized genus/species. An anaerobic bacterium, Clostridium frigidicarnis was demonstrated to be lytic for amoebae. This preliminary work demonstrates that the water environment in the vicinity of humans is a reservoir of ARB, including well-known pathogens for which amoebae and/or water was not recognized earlier as a possible reservoir.

Silver Nanoparticles in the Water Environment in Malaysia: Inspection, characterization, removal, modeling, and future perspective.

Abstract: The current status of silver nanoparticles (AgNPs) in the water environment in Malaysia was examined and reported. For inspection, two rivers and two sewage treatment plants (STPs) were selected. Two activated carbons derived from oil palm (ACfOPS) and coconut (ACfCS) shells were proposed as the adsorbent to remove AgNPs. It was found that the concentrations of AgNPs in the rivers and STPs are in the ranges of 0.13 to 10.16 mg L−1 and 0.13 to 20.02 mg L−1, respectively, with the highest concentration measured in July. ACfOPS and ACfCS removed up to 99.6 and 99.9% of AgNPs, respectively, from the water. The interaction mechanism between AgNPs and the activated carbon surface employed in this work was mainly the electrostatic force interaction via binding Ag+ with O− presented in the activated carbon to form AgO. Fifteen kinetic models were compared statistically to describe the removal of AgNPs. It was found that the experimental adsorption data can be best described using the mixed 1,2-order model. Therefore, this model has the potential to be a candidate for a general model to describe AgNPs adsorption using numerous materials, its validation of which has been confirmed with other material data from previous works.