Assimilation Efficiency Of Cd Research Articles

Bioavailability of dissolved and sediment-bound metals to a marine deposit-feeding polychaete

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 178:281-293 (1999) - doi:10.3354/meps178281 Bioavailability of dissolved and sediment-bound metals to a marine deposit-feeding polychaete Wen-Xiong Wang1,2,*, Ian Stupakoff1, Nicholas S. Fisher1 1Marine Sciences Research Center, State University of New York, Stony Brook, New York 11794-5000, USA 2Department of Biology, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong *Present address: Department of Biology, HKUST, Clear Water Bay, Kowloon, Hong Kong. E-mail: wwang@ust.hk ABSTRACT: Assimilation efficiencies (AEs) of trace elements (Ag, Cd, Co, Se and Zn) in a marine deposit-feeding polychaete, Nereis succinea, from ingested sediments were measured using a pulse-chase radiotracer feeding technique. Radiolabeled sediments were encapsulated and fed to the worms for 1 h, after which the worms were allowed to depurate their ingested materials for 3 d. The ranges of AEs were 12 to 36% for Ag, 5 to 44% for Cd, 35 to 96% for Co, 29 to 60% for Se and 21 to 59% for Zn. Trace metal assimilation was little affected by sediment source and sediment grain size. Metals (Ag, Cd, Co and Zn) associated with anoxic sediments were assimilated with a significantly lower efficiency than metals from oxic sediments. The AE of Cd decreased with the duration of sediment radiolabeling; AEs of Ag, Co, Se and Zn were weakly affected by sediment aging. Metal uptake in worms from the dissolved phase was proportional to metal concentration in the dissolved phase, although there was some evidence of Cd and Zn regulation in response to an increase in ambient concentrations. Uptake rate constants were highest for Ag, followed by Zn > Co > Cd > Se. By incorporating metal influx from both the dissolved and particulate (sediment) phases, a bioenergetic-based kinetic model indicates that most (>98%) of the Cd, Co, Se and Zn in polychaetes arises from sediment ingestion due to the high ingestion rates of these animals and the low uptake rate of metals from the dissolved phase (porewater or overlying water). For Ag, approximately 5 to 35% is due to uptake from the dissolved phase. Our study suggests that the establishment of sediment quality criteria must consider sediment as a potentially important source for metal uptake in benthic invertebrates. KEY WORDS: Bioavailability · Kinetic modeling · Polychaetes · Sediments · Cadmium · Cobalt · Selenium · Silver · Zinc Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 178. Publication date: March 17, 1999 Print ISSN:0171-8630; Online ISSN:1616-1599 Copyright © 1999 Inter-Research.

The trophic transfer of Cd, Cr, and Se in the barnacle Balanus amphitrite from planktonic food

We determined the assimilation efficiencies (AEs) and efflux rate constants of Cd, Cr, and Se in barnacles Balanus amphitrite feeding on diverse planktonic prey. The measured AEs of Cd, Cr, and Se for zooplankton prey (brine shrimp Artemia salina larvae and copepods Canthocalanus pauper and Temora turbinata) were 53 to 88, 32 to 59, and 63 to 76%, respectively, and for diatom diets were 35 to 86, 22 to 26, and 79%, respectively. Distribution of metals in the soft tissues of zooplankton could not account for the variability of AE for each metal, but did explain the variability of AE among different metals. Metal distribution in the cytoplasm of diatoms determined the variability of AEs among metals. There was a significant correlation between Cd and Zn in AE and efflux rate constant. No relationship in AE or efflux rate was found for the other metals. The efflux rate constants in B. amphitrite were 0.007, 0.020, and 0.014 d -1 for Cd, Cr, and Se, respectively. Cd concentrations in barnacles, predicted by a simple bioenergetic-based kinetic model, were comparable to the actual concentrations measured in the field when phytoplankton was considered as the primary Cd source. Cd concentrations predicted by the model were much higher than the field measurements when copepods were assumed as the sole food source for barnacles. Trophic transfer appeared to be responsible for Cd accumulation in barnacles. Many biological and geochemical processes can affect metal accumulation in barnacles. Our study demonstrated that biological processes must be considered to interpret metal concentrations in barnacles when the barnacles are used to monitor coastal contamination.

Accumulation of trace elements in a marine copepod

We measured assimilation efficiencies (AEs) from ingested algal food, uptake rates from the dissolved phase, and efflux rate constants of five trace elements (Ag, Cd, Co, Se and Zn) in the marine copepod Temora longicornis. AEs of Ag, Cd, Co, Se, and Zn from two diatom diets were 13, 35, 14, 59, and 61%, respectively. AEs of metals from ingested natural seston collected during the spring phytoplankton bloom in Long Island Sound were comparable to AEs from diatoms. The assimilation of all trace elements within the T. longicornis gut took longer (4–15 h) than the gut passage time of ingested food particles. The rate constant of metal uptake from the dissolved phase was highest for Ag, followed by Zn > Cd > Co > Se. Efflux rate constants for all trace elements ranged from 0.08 to 0.30 d−1, indicating that metals were regenerated at a very fast rate in these animals. Generally, the efflux rate of metals was higher following uptake from food than uptake from the dissolved phase. The retention half‐times of trace elements in copepod carcasses were 0.6–3.3 d. A bioenergetic‐based kinetic model was used to quantify the relative importance of metal uptake in copepods from different pathways. The model indicates that under conditions typically encountered by copepods in nature, >50% of Zn and >98% of Se in copepods are obtained from ingested food. For Ag, Cd, and Co, >50% accumulates from the dissolved phase. The relative importance of trace element uptake from the dissolved phase vs. particulate ingestion in the overall metal uptake depends greatly on the metal AE, the feeding rate of copepods, and the partition coefficient of metals in ingested food particles.

Modeling the influence of body size on trace element accumulation in the mussel Mytilus edulis

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 161:103-115 (1997) - doi:10.3354/meps161103 Modeling the influence of body size on trace element accumulation in the mussel Mytilus edulis Wen-Xiong Wang*, Nicholas S. Fisher** Marine Sciences Research Center, State University of New York, Stony Brook, New York 11794-5000, USA *Present address: Department of Biology, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong **Addressee for correspondence. E-mail: nfisher@ccmail.sunysb.edu We measured assimilation efficiencies (AEs) from ingested algal food, uptake rates from the dissolved phase, and efflux rate constants of 4 trace elements (Cd, Co, Se and Zn) in 3 size classes (1.5, 2.5, and 5.0 cm) of the mussel Mytilus edulis. AEs of Se and Zn remained constant among the 3 body sizes. AEs of Cd decreased with increasing body size, whereas AEs of Co increased with body size. The rate constant of metal uptake from the dissolved phase decreased with increasing body size, but the calculated metal absorption efficiencies remained relatively constant or increased slightly in larger mussels. Efflux rate constants were comparable among the 3 body sizes, except for Cd which was lost about 2 times faster in the smaller mussels than in the largest mussels. A bioenergetic-based kinetic model was used to calculate the allometric coefficient (b) of metal accumulation with mussel body size; predicted b values were comparable to field measurements. However, b increased exponentially with the growth rate constant, indicating that no single b value is likely to be observed in nature for a specific metal. The growth rate constant is needed for the model to predict metal concentration and allometry of metal accumulation in mussels, especially for smaller mussels. The relative importance of trace element uptake from the dissolved phase versus particulate ingestion in the overall metal uptake in mussels was relatively independent of mussel body size, primarily because the influx rates from the dissolved phase and from food were comparably related to body size. Allometry · Mussels · Bioaccumulation · Modeling · Cadmium · Cobalt · Selenium · Zinc Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 161. Publication date: December 31, 1997 Print ISSN:0171-8630; Online ISSN:1616-1599 Copyright © 1997 Inter-Research.