Water environment

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

Phytofiltration of arsenic and cadmium from the water environment using Micranthemum umbrosum

Abstract: Heavy metal pollution in aquatic environment due to natural sources and anthropogenicactivities, is posing a dreadful threat to the human health Among different heavy metals,arsenic (As) and cadmium (Cd) are the two most toxic and carcinogenic agent that extensivelycontaminates the water bodies There are some physical and chemical remediation methodsthat have some limitations like high production technology, costly, destruction of native microflora and fauna, and creation of secondary pollutions In contrast, phytofiltration is a novel,cost effective, environmental friendly, aesthetic and solar-driven technology, using aquaticplants to remove As and Cd from contaminated water without causing any or little secondarypollution A small number of aquatic plants were identified to uptake contaminants fromaquatic environment Among them very few could accumulate more than one pollutant intheir bodies Micranthemum umbrosum (JF Gmel) SF Blake, commonly known as Waterfern, Baby’s tears, or Pearl grass, belongs to the family Linderniaceae, is one of them, thatsignificantly absorbs both As and Cd from contaminated waterAfter culturing M umbrosum for 7 days in a hydroponic experiment, the accumulation ofabout 1220 μg As g-1 and 800 μg Cd g-1 were observed in the leaves, from 1000 μg As L-1 and1000 μg Cd L-1 of water, respectively and it can removed 793–895% As and 60–731% Cdfrom 200 to 1000 μg As L-1 and 300 to 3000 μg Cd L-1 solutions, respectively Plant andwater samples were analyzed for assessing the As and Cd accumulations, translocations,phytotoxic effects, uptake mechanisms and kinetics, and for evaluating the potential of Mumbrosum as As and Cd phytofiltratorFor As treatment, root to stem and stem to leaf translocation factors greater than 10 indicatedthat accumulation of As in leaves was large compared to that in stem and roots but there arelittle differences in accumulation of Cd in roots, leaves and stem It is easy to clean up aquaticenvironment rather than soil due to most of the soil phytoremediators accumulatedcontaminants in their root parts which is sometimes very difficult to harvest and removal fromthe contaminated soil environment However, the absorption pattern of As and Cd within Mumbrosum was leaf > stem > root Bio-concentration factors (2350 for As and 3027 for Cd)for M umbrosum were higher than for other As and Cd phytoremediators, indicates itshyperaccumulation of As and Cd from contaminated water environment The analysis of different photosynthetic pigments and macro micro-nutrient concentration within plant bodyindicated that the plant showed more resistance to internal and external As concentrationsthan to that of CdAbsorption uptake kinetics within M umbrosum was studied by using Michaelis Mentenequation from different As species like arsenite, monomethylarsinic acid (MMAA),dimethylarsinic acid (DMAA) and Cd The uptake of inorganic As species was much greaterthan that of organic As and was found at above the substrate concentration Concentrationdependent arsenite and Cd…

Experimental assessment of OFDM and DSSS modulations for use in littoral waters underwater acoustic communications

Abstract: Robust and reliable horizontal long-range acoustic communications in littoral water environment (water depth /spl sim/100 m; range over 10 km) is known to be a very challenging task. Most commercially available acoustic modems (COTS) therefore use classical modulation schemes, such as FSK (frequency shift keying), with limited data rate for the ranges of interest. This paper addresses experimental results recently obtained with two other approaches which both aim at providing robust transmissions with higher bit rate: first is a set of OFDM (orthogonal frequency division multiplex) modulations in which data are transmitted by modulating a large number of orthogonal carriers, second approach is an application of DSSS (direct sequence spread spectrum) techniques where the transmitted symbols are spread over the used bandwidth with a pseudo-noise binary.