Heavy Metals, Trophic Levels, Food Chains, and Future Risks

1975 ◽  
Vol 189 (1096) ◽  
pp. 305-332 ◽  

A range of chlorinated hydrocarbons derived from C 1 and C 2 hydrocarbons is manufactured industrially. They are used as intermediates for further chemical manufacture and also outside the chemical industry as solvents or carriers. In the latter category losses in use are eventually dispersed to the environment. The distribution of some of these compounds, including chloroform, carbon tetrachloride, trichloroethylene, perchloroethylene and trichloroethane, in the environment (air, water and marine sediments) has been investigated and the results are presented. The concentrations found have been compared with acute toxicity levels to fish and other aquatic organisms, ascertained by laboratory bioassay. The occurrence of the compounds has been determined in a number of marine organisms, especially those at higher trophic levels, and the accumulation of some of them has been investigated in the laboratory. Chemical and microbial degradation processes have been studied in the laboratory to help determine the course of their removal from the aqueous and aerial environment, and the half lives of some of the compounds have been estimated. It is concluded that these compounds are not persistent in the environment, and that there is no significant bioaccumulation in marine food chains.


2020 ◽  
Vol 3 (1) ◽  
pp. 101
Author(s):  
Gabrielle Diniz dos Santos ◽  
Gil Dutra Furtado ◽  
Cíntia Cleub Neves Batista

Nowadays, the vast majority of aquatic bodies suffer some kind of anthropic influence due to the great expansion of urban areas and consequently industrial areas, with the pollution coming into such environments. One of the types of pollutants present in the environment are heavy metals, which are found naturally in water bodies due to the weathering of rocks and volcanic activities. The present work is of bibliographic nature, based on searches in the bibliography pertinent to the theme. It is possible to state that with anthropic intervention, such metals become common and are found in greater quantities in the environment in a free form. Thus, some of the most common sources of release of heavy metals into the environment are fertilizers, pesticides, coal and oil combustion, vehicular emissions, mining, smelting, refinement and incineration of urban and industrial waste. Thus making contamination of humans with heavy metals more and more common, one of the most common and easy forms of contamination is through food. The absorption of metals by animals can occur in two ways, bioaccumulation and biomagnification. The first occurs through the diffusion or ingestion of the dissolved metals in the water, which occur through the gills or the digestive tract and then lodges in the animals' tissues, so that the organism cannot absorb it, thus obtaining a bioaccumulative character. In the trophic biomagnification or magnification, the concentration of metals in the organism occurs gradually through the trophic levels. The transfer of contaminants through the food chain characterizes such a process that passes from producers to consumers and the longer the chain, the greater the concentration on the final consumer. Therefore, we can emphasize that the concentration and absorption content of such substances are relative and depend on several environmental and physiological factors that vary between species of beings. Metal poisoning can cause serious damage, such as low fertility, decreased immune defenses, reduced growth rate and pathologies that can lead to senescence. Metals can cause different problems in humans, most of which are of a motor nature, as they directly affect the central nervous system (CNS), and can cause memory loss, uncontrolled limb tremors, muscle atrophy, kidney injuries, among others.


AGROFOR ◽  
2016 ◽  
Vol 1 (3) ◽  
Author(s):  
Primož ZIDAR ◽  
Špela KRŽIŠNIK ◽  
Marta DEBELJAK ◽  
Suzana ŽIŽEK ◽  
Katarina VOGEL MIKUŠ

More than 500 years of mercury (Hg) production in Idrija (Slovenia) resulted in aconsiderable pollution of Idrija region with Hg. Although the mine is closed formore than 20 years, the total soil concentration of Hg may still reach up to severalhundred mgkg-1dry weightin local gardens and more that thousand inother urbanregions. Hg in soil undergoesdifferent chemical transformations and in someformsit may enterplants and higher trophic levelsin food chains, also withbiomagnification pattern.The local population is, besides air and dust, thus exposedto mercury also via consumption of locally produced food.Several studies showedthat the increased level of selenium in soil may reduce the uptake of mercury inplants but very few include other trophic levels in a food chain as well.In our pilotstudy we followed an impact of Seon Hg transport from soil to plants(Lactucasativa) and further to soil dwelling animals (Porcellioscaber). Lettuce wasplanted in a contaminated soil from Idrija and in soil with added HgCl2. The leavesof half of the plants weresprayed with Sesolution (5μg L-1)threeand five weeksafter planting.After six weeks plants were analyzed for Hg and Se and offered asfood to terrestrial isopods for two weeks. Our preliminary results revealed thatfoliar treatment of plants with Se may affect Hg accumulation in plants andtherefore further transport of Hg across the food chain.


2019 ◽  
Vol 193 (2) ◽  
pp. 536-547 ◽  
Author(s):  
Manoj Kumar ◽  
Neelima Gupta ◽  
Arun Ratn ◽  
Yashika Awasthi ◽  
Rajesh Prasad ◽  
...  

2009 ◽  
Vol 2 (3) ◽  
pp. 177-183 ◽  
Author(s):  
Jana Kovářová ◽  
Zdeňka Svobodová

Can thiol compounds be used as biomarkers of aquatic ecosystem contamination by cadmium?Due to anthropogenic activities, heavy metals still represent a threat for various trophic levels. If aquatic animals are exposed to heavy metals we can obviously observe considerable toxicity. It is well known that an organism affected by cadmium (Cd) synthesize low molecular mass thiol compounds rich in cysteine (Cys), such as metallothioneins (MT) and glutathione (GSH/GSSG). The aim of this study was to summarize the effect of Cd on level of thiol compounds in aquatic organisms, and evaluate that the concentrations of thiol compounds are effective indicators of Cd water pollution and explain their potential use in biomonitoring applications.


Author(s):  
Núria Galiana ◽  
Jean-François Arnoldi ◽  
Matthieu Barbier ◽  
Amandine Acloque ◽  
Claire de Mazancourt ◽  
...  

AbstractThe biomass distribution across trophic levels (biomass pyramid), and cascading responses to perturbations (trophic cascades), are archetypal representatives of the interconnected set of static and dynamical properties of food chains. A vast literature has explored their respective ecological drivers, sometimes generating correlations between them. Here we instead reveal a fundamental connection: both pyramids and cascades reflect the dynamical sensitivity of the food chain to changes in species intrinsic rates. We deduce a direct relationship between cascades and pyramids, modulated by what we call trophic dissipation – a synthetic concept that encodes the contribution of top-down propagation of consumer losses in the biomass pyramid. Predictable across-ecosystem patterns emerge when systems are in similar regimes of trophic dissipation. Data from 31 aquatic mesocosm experiments demonstrate how our approach can reveal the causal mechanisms linking trophic cascades and biomass distributions, thus providing a road map to deduce reliable predictions from empirical patterns.


1985 ◽  
Vol 36 (5) ◽  
pp. 683 ◽  
Author(s):  
PD Nichols ◽  
DW Klumpp ◽  
RB Johns

Stable carbon isotope determinations have been used to obtain a general background to food chains being studied by a range of chemical and biological techniques. δ13C values indicate that animals (δ13CC - 11.4‰ to - 14.9‰), including two locally important commercial fish, Platycephalus laevigatus (rock flathead) and Hyporhamphus melanochir (southern sea garfish), from the Corner Inlet seagrass and non-seagrass communities are dependent to varying degrees upon seagrass (δ13C - 7.0‰ to - 9.3‰) and benthic algae for their carbon source. The largest changes in δ13C values in the food chains is at the point involving seagrasses and their direct herbivores. The latter have more negative δ13C values (H. melanochir - 12.1%o, isopods - 11.4%o). Little or no change in δ13C values is apparent at the higher trophic levels (carnivores - 13 .0‰ to - 14.9‰). Epiphytic material on the fresh leaves of the two seagrass species in the Inlet is depleted in 13C when compared with the seagrass leaves. An opposite effect is observed for epiphytic material on Posidonia australis detritus.


Sign in / Sign up

Export Citation Format

Share Document