Bioaccumulation of 137Cs in pelagic food webs in the Norwegian and Barents Seas

Knowledge and documentation of the levels of radioactive contamination in fish stocks important to Norwegian fisheries is of major importance to Norwegian consumers and fish export industry. In the present study, the bioaccumulation of caesium-137 ((137)Cs) has been investigated in marine food webs in the Barents and Norwegian Seas. The contents of (137)Cs in the different organisms were generally low (<1 Bq kg(-1) wet weight), but a marked bioaccumulation was apparent: The concentration of (137)Cs was about 10-fold higher in the harbour porpoise Phocoena phocoena, representing the upper level of the food web, than in the amphipod Themisto sp., representing the lower level of the food web. The Concentration Factors (CF=Bq kg(-1) wet weight/Bq l(-1) seawater) increased from 10+/-3 for a mixed sample of krill and amphipods to 165+/-5 for harbour porpoises.     

Redistribution of slurry components as influenced by injection method, soil, and slurry properties

The distribution of moisture, degradable C, and N after direct injection of slurry can affect the turnover and plant availability of slurry N. This study examined effects of injection method, soil conditions, and slurry properties on the infiltration of several slurry components under practical conditions. The water retention capacity of 22 pig and cattle slurries was quantified by dialysis at -0.016, -0.047, and -0.100 MPa. All slurries followed the relationship: relative water loss = 1/(1 + aVS[volatile solids]), indicating that retention of liquids in the slurry injection zone can be predicted from slurry VS and soil water potential. Two-disc injection and harrow tine injection were simulated (no slurry applied) in five trials. Two trials indicated that disc injection resulted in higher permeability compared with harrow tine injection. In a separate experiment, soil moisture and dissolved ions were monitored in and around injection slits amended with pig or cattle slurry. Moisture gradients, which were recorded with small printed-circuit-board (PCB) time-domain-reflectometry (TDR) probes, were temporally stable and reestablished following rainfall. Slit sections with pig and cattle slurry containing 13C-acetate and 15N-ammonium showed a shift in the 13C to 15N ratio of the injection zone within 24 h, which was explained by removal of dissolved C and/or retention of NH4+. Cattle slurry was more concentrated around the injection slit than pig slurry, and greater contact between slurry and soil was obtained with harrow tine injection. The heterogeneity of slurry C and N distribution after direct injection should be accounted for in models describing slurry N turnover.     

Characterisation of the abiotic degradation pathways of oxytetracyclines in soil interstitial water using LC-MS-MS

The fate of oxytetracyclines (OTCs) in soil interstitial water was investigated and the structure of a number of degradation products elucidated in a time-related experiment. A previously developed separation method for LC–MS–MS able to base separate and quantify OTC and three of its epimers and degradation products was applied. Compounds detected were 4-epi-oxytetracycline (EOTC) (t_R=3.0 min), OTC (t_R=4.4 min), -apo-oxytetracycline (-apo-OTC) (t_R=11.4 min) and β-apo-oxytetracycline (β-apo-OTC) (t_R=18.4 min). Furthermore, we tentatively identified 4-epi-N-desmethyl-oxytetracycline (E-N-DM-OTC) (t_R=3.0 min), N-desmethyl-oxytetracycline (N-DM-OTC) (t_R=3.5), N-didesmethyl-oxytetracycline (N-DDM-OTC), 4-epi-N-didesmethyl-oxytetracycline (E-N-DDM-OTC) (t_R=3.7 and 4.7 min) and 2-acetyl-2-decarboxamido-oxytetracycline (t_R=8.7) in all samples. Most compounds were only present in trace concentrations (less than 2%) relative to the parent OTC. EOTC was on the other hand formed up to a ratio of 0.6 relative to parent OTC concentration. Only EOTC, E-N-DM-OTC, N-DM-OTC, N-DDM-OTC and E-N-DDM-OTC were formed during the time-related experiment. All other compounds were probably only present as impurities in the spiked OTC formulation as they declined in concentration from the start of the experiment. Half-lives (T_1/2, days) of the OTCs in soil interstitial water were in the order of 2 days (EOTC) to 270 days (β-apo-OTC).     

Influence of plant growth on degradation of linear alkylbenzene sulfonate in sludge-amended soil

Widespread application of sewage sludge to agricultural soils in Denmark has led to concern about the possible accumulation and effects of linear alkylbenzene sulfonate (LAS) in the soil ecosystem. Therefore, we have studied the uptake and degradation of LAS in greenhouse pot experiments. Sewage sludge was incorporated into a sandy soil to give a range from very low to very high applications (0.4 to 90 Mg dry wt. ha(-1)). In addition, LAS was added as water solutions. The soil was transferred to pots and sown with barley (Hordeum vulgare L. cv. Apex), rape (Brassica napus L. cv. Hyola 401), or carrot (Daucus carota L.). Also, plant-free controls were established. For all additions there was no plant uptake above the detection limit at 0.5 mg LAS kg(-1) d.w, but plant growth stimulated the degradation. With a growth period of 30 d, LAS concentrations in soil from pots with rape had dropped from 27 to 1.4 mg kg(-1) dry wt., but in plant-free pots the concentration decreased only to 2.4 mg kg(-1) dry wt. When LAS was added as a spike, the final concentration in soil from planted pots was 0.7 mg kg(-1) dry wt., but in pots without plants the final concentration was much higher (2.5 mg kg(-1) dry wt.). During degradation, the relative fraction of homologues C10, C11, and C12 decreased, while C13 increased.     

Energy budgest,growth and filtration rates in Mytilus edulis at different algal concentrations

Growth of Mytilus edulis L. was measured in aquaria with through-flowing sea water at different levels of constant algal concentrations. The amount of food and oxygen consumed by the mussels were measured over given periods as well as the changes in dry organic weight during the same periods. From these parameters it was possible to make simple energy budgets and to compare the estimated growth with actual growth, and, further, to determine growth efficiences at different food levels. Energy budgets were made for mussels grown at algal concentrations of 0, 1.6×10³, 3.0×10³ and 26.0×10³ Phaeodactylum tricornutum cells x ml^-1. The estimated growth was found to be close to actual growth at algal concentrations above maintenance level and the net growth efficiency was found to be between 18% (3.0×10³ cells x ml^-1) and 61% (26×10³ cells x ml^-1). It has been shown that the filtration rate is independent of algal concentrations between about 1.5×10³ to 30×10³ P. tricornutum cells x ml^-1. Outside this range a decrease in filtration rate was noticed.