Relationships between carbon and cadmium uptake in Mytilus edulis

The influence of six different food rations on carbon assimilation and net incorporation, and on shell and soft body growth in Mytilus edulis was determined over a 75-d period, starting in 1981. Using a triple tracer technique, interrelationships between carbon net incorporation (C-14) and cadmium accumulation from food (Cd-109) and seawater (Cd-115m) were investigated. With decreasing food rations there was an exponential increase of the carbon assimilation efficiency from 35 to 76% while the net incorporation efficiency increased approximately linearly, ranging from 15 to 32% at the highest and lowest food supply levels respectively. The carbon assimilation efficiency adapted to new conditions within 1 to 2 d while the adaptation of the net incorporation efficiency took about one month. Shells kept growing, even when the soft body lost weight. Within a 42-d elimination period, when the soft body lost 58% of the incorporated carbon, nothing was released from the shells. Cadmium accumulation from food was closely interrelated with carbon net incorporation and exhibited the same uptake kinetics. No homogeneity was found between carbon net incorporation and cadmium accumulation from seawater, and between the elimination of carbon and cadmium.     

What drives the water quality changes in the Selenga Basin: climate change or socio-economic development?

Regional Environmental Change - Lake Baikal is the largest near-surface global freshwater source and of high interest for water quality alterations, as deterioration of water quality is a main...     

Simultaneous Concentration of Bovine Viruses and Agricultural Zoonotic Bacteria from Water Using Sodocalcic Glass Wool Filters

Infiltration and runoff from manured agricultural fields can result in livestock pathogens reaching groundwater and surface waters. Here, we measured the effectiveness of glass wool filters to simultaneously concentrate enteric viruses and bacteria of bovine origin from water. The recovery efficiencies were determined for bovine viral diarrhea virus types 1 and 2, bovine rotavirus group A, bovine coronavirus, poliovirus Sabin III, toxigenic Escherichia coli ,and Campylobacter jejuni seeded into water with three different turbidity levels (0.5, 215, and 447 NTU). Twenty liters of dechlorinated tap water (pH 7) were seeded with the test organisms, and then passed through a glass wool filter using a peristaltic pump (flow rate = 1 liter min^?1). Retained organisms were eluted from the filters by passing beef extract-glycine buffer (pH 9.5) in the direction opposite of sample flow. Recovered organisms were enumerated by qPCR except for C. jejuni, which was quantified by culture. Mean recovery efficiencies ranged from 55 to 33 % for the bacteria and 58 to 16 % for the viruses. Using bootstrapping techniques combined with Analysis of Variance, recovery efficiencies were found to differ among the pathogen types tested at the two lowest turbidity levels; however, for a given pathogen type turbidity did not affect recovery except for C. jejuni. Glass wool filtration is a cost-effective method for concentrating several waterborne pathogens of bovine origin simultaneously, although recovery may be low for some specific taxa such as bovine viral diarrhea virus 1.     

Influence of food quantity on the kinetics of cadmium uptake and loss via food and seawater in Mytilus edulis

The difference between the cadmium uptake via food and seawater in Mytilus edulis has been studied. This was done by labelling algae with Cd-109 and seawater with Cd-115m. Mussels were fed on six different quantities of Isochrysis galbana. Cadmium uptake via algae was more efficient at low food levels, while accumulation from seawater was linearly correlated with food quantities. Cadmium from food contributed only little to the body burden (0.2–0.5%). Half-lives for the elimination of cadmium ranged from 96–190 d and increased with decreasing availability of algae, presumably due to slowed down metabolism. Differences in elimination patterns suggest a release of both isotopes from different storage depots. A computer model shows that the food pathway can only play a significant role if algae are highly contaminated. It also demonstrates the paradox that in long-term studies the highest contribution of food-derived cadmium to the body burden must be expected near maintenance food concentrations.     

Regional patterns of heavy metal exposure and contamination in the fish fauna of the Kharaa River basin (Mongolia)

Regional Environmental Change - Past and present gold mining operations scattered throughout the Kharaa River basin, Mongolia, have been identified as a major source of heavy metal and metalloid...     

Biogeochemical patterns in a river network along a land use gradient

The Bode catchment (Germany) shows strong land use gradients from forested parts of the National Park (23 % of total land cover) to agricultural (70 %) and urbanised areas (7 %). It is part of the Terrestrial Environmental Observatories of the German Helmholtz association. We performed a biogeochemical analysis of the entire river network. Surface water was sampled at 21 headwaters and at ten downstream sites, before (in early spring) and during the growing season (in late summer). Many parameters showed lower concentrations in headwaters than in downstream reaches, among them nutrients (ammonium, nitrate and phosphorus), dissolved copper and seston dry mass. Nitrate and phosphorus concentrations were positively related to the proportion of agricultural area within the catchment. Punctual anthropogenic loads affected some parameters such as chloride and arsenic. Chlorophyll a concentration and total phosphorus in surface waters were positively related. The concentration of dissolved organic carbon (DOC) was higher in summer than in spring, whereas the molecular size of DOC was lower in summer. The specific UV absorption at 254 nm, indicating the content of humic substances, was higher in headwaters than in downstream reaches and was positively related to the proportion of forest within the catchment. CO₂ oversaturation of the water was higher downstream compared with headwaters and was higher in summer than in spring. It was correlated negatively with oxygen saturation and positively with DOC concentration but negatively with DOC quality (molecular size and humic content). A principle component analysis clearly separated the effects of site (44 %) and season (15 %), demonstrating the strong effect of land use on biogeochemical parameters.