Search results for "Mercury"

Effects of low mercury concentration exposure on hatching, growth and survival in the Artemia strain La Mata parthenogenetic diploid

1998

The effects of exposure to low levels of mercury in the developmental events occurring from hatching to adult life in the Artemia strain La Mata parthenogenetic diploid were studied. Mercury (5, 25, 50, 250 and 500 nM) added at the beginning of incubation had no effect on hatching and emergence. We studied mercury effects on the growth of viviparous nauplii obtained from mothers that had been acclimatised to 25 nM of mercury for all their lives. Measurements of the length of Artemia individuals were carried out using video recordings in order to reduce the stress experienced by the test animals. The mean body length of the mercury-treated group (25 nM) was higher than that of the control an…

Constant-potential electrolysis: determination of diffusion coefficients of thallium by using a hanging mercury drop electrode.

1976

The technique of constant-potential electrolysis at a stationary spherical electrode (hanging mercury drop) was investigated for the determination of the diffusion coefficient of Tl(I) in sodium citrate-sodium hydroxide medium and of Tl in mercury. Current-time curves, at controlled potential, were obtained, covering periods from 1 to 25 sec after the start of the electrolysis. The influence of applied potential, time of electrolysis, convection and shielding of the electrode was studied.

Polarographic determination of glycine with a dropping copper amalgam electrode

1975

The anodic oxidation of a dropping copper amalgam electrode in presence of dilute solutions of glycine in 0.50 M NaClO4 has been studied. An anodic wave at −0.28V (SCE) is observed, yielded by diffusion of glycinate anion in the solution towards the electrode surface. The wave-heights increase with the glycinate concentration (function of glycine concentration and pH value) until the anodic oxidation is controlled by the metal diffusion into mercury. The effect of pH is interpreted by attributing it to the depolarizer effects at glycinate anion even though the zwitterion is present in much larger concentrations. The applicability of anodic oxidation of a dropping copper amalgam electrode in…

The influence of environmental conditions on the lifespan of mosses under long-term active biomonitoring

2021

Abstract Biomonitoring with living organisms is most often used in order to gather quick information about environmental quality – for example the level of heavy metals polluting the air. Experiments are not often performed when the bioindicator is exposed to pollutants over the long time (6 months and more) because this period required to obtain credible results and the risk not yet studied of physiological changes and of degeneration of the living material which would undoubtedly affect the biomonitoring results. The aim of study was to evaluate the physiological condition of Pleurozium schreberi moss species subjected to continuous exposure for a year, using the moss-bag method, under va…

"Mercury as a Global Pollutant" -- International conference

1997

Blackfly Larvae (Simulium spp.) Can Intensify Methylmercury Biomagnification in Boreal Food Webs

2020

AbstractGlobal pollution of mercury (Hg) threatens ecosystem and human health. We measured total Hg (THg) and monomethylmercury (MMHg) concentrations in filter-feeding blackfly (Simulium spp.) larvae in the inflows and the outflows of six boreal lakes with no Hg point source pollution. THg in the larvae ranged from 0.03 to 0.31 mg kg−1 dw and MMHg between 0.02 and 0.25 mg kg−1 dw. The proportion of MMHg in the larvae was 74 ± 0.16% and ranged from 43 to 98% of THg, the highest proportions being comparable to those typically found in aquatic predatory insects and fish. We compared the larvae MMHg concentrations to river water quality, catchment land-use, and to size-adjusted lake pike THg da…

Total mercury and methyl-mercury contents and accumulation in polar microbial mats.

2014

Although polar regions are considered isolated and pristine areas, the organisms that inhabit these zones are exposed to global pollution. Heavy metals, such as mercury, are global pollutants and can reach almost any location on Earth. Mercury may come from natural, volcanic or geological sources, or result from anthropogenic sources, in particular industrial or mining activities. In this study, we have investigated one of the most prominent biological non-marine communities in both polar regions, microbial mats, in terms of their Hg and methyl-mercury (MeHg) concentrations and accumulation capacities. The main hypotheses posed argued on the importance of different factors, and to test them…

Mercury levels in sediments of central Mediterranean Sea: a 150+ year record from box-cores recovered in the Strait of Sicily.

2006

To evaluate the degree of anthropogenic mercury pollution, Hg contents have been measured for box-core sediments sampled along three nearshore-offshore transects in the Strait of Sicily and well constrained for their mineralogy, bulk geochemistry and TOC%. Hg values are generally low (from 15 to 70 microg kg(-1)); however, depth profiles clearly display upcore rising concentrations (up to 202 microg kg(-1) near the SE Sicily coast) that are attributed to anthropogenic load. Based on (210)Pb chronology, these trends are more dramatic across the last 20-30 years. Geogenic influence is thought to explain some anomalies related to volcanic emission and geothermal activity. Combined effects due …

Gill ATPase activity in Procambarus clarkii as an indicator of heavy metal pollution.

1989

Lake Albufera and the surrounding rice field waters are subjected to very heavy loads of sewage and toxic industrial residues, including heavy metals, from the many urban and waste waters of this area. The American red crayfish, Procambarus clarkii have a high resistance to toxic effects of heavy metals. The sublethal effects of heavy metals on gills of fish and aquatic invertebrates have been extensively studied. Some metabolic disturbances and histologic damages have been reported, as well as osmoregulation alterations. However, little work has been done about the effect of heavy metals on Na,K and Mg-ATPases of freshwater invertebrate gills. Na,K-ATPase is the prime mediator of ion trans…

Trends in soil mercury stock associated with pollution sources on a Mediterranean island (Majorca, Spain)

2021

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