Hydrothermal carbonization of food waste and associated packaging materials for energy source generation

Hydrothermal carbonization (HTC) is a thermal conversion technique that converts food wastes and associated packaging materials to a valuable, energy-rich resource. Food waste collected from local restaurants was carbonized over time at different temperatures (225, 250 and 275 °C) and solids concentrations to determine how process conditions influence carbonization product properties and composition. Experiments were also conducted to determine the influence of packaging material on food waste carbonization. Results indicate the majority of initial carbon remains integrated within the solid-phase at the solids concentrations and reaction temperatures evaluated. Initial solids concentration influences carbon distribution because of increased compound solubilization, while changes in reaction temperature imparted little change on carbon distribution. The presence of packaging materials significantly influences the energy content of the recovered solids. As the proportion of packaging materials increase, the energy content of recovered solids decreases because of the low energetic retention associated with the packaging materials. HTC results in net positive energy balances at all conditions, except at a 5% (dry wt.) solids concentration. Carbonization of food waste and associated packaging materials also results in net positive balances, but energy needs for solids post-processing are significant. Advantages associated with carbonization are not fully realized when only evaluating process energetics. A more detailed life cycle assessment is needed for a more complete comparison of processes.     

Disposition of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) in two Norwegian epibenthic marine food webs

Polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) are a group of halogenated hydrocarbons, comprising 210 different, theoretically possible congeners. They are relatively hydrophobic and persistent to biodegradation, thereby rendering them subject to bioaccumulation. This study was conducted in Frierfjord and Eidangerfjord in the Grenland fjord system, Norway, heavily polluted by PCDD/PCDF discharges from the magnesium production at Herøya from 1951 to 2001. Pooled samples of surface-sediments and the following organisms were collected for the Frierfjord and Eidangerfjord study areas: common shrimp (Crangon crangon), polychaetes (mainly Nereis diversicolor), shore crab (Carcinus maenas), cod (Gadus morhua), flounder (Platichthys flesus), trout (Salmo trutta), herring (Clupea harengus), benthic amphipods and zooplankton. Concentrations of 2,3,7,8-PCDD/Fs were quantified in pooled samples for all species. The relative abundances of stable isotopes of nitrogen (δ¹⁵N) were evaluated in the organisms as a measure of chemically-derived trophic level. Contrary to earlier studies on other persistent organochlorines, it was found that the concentrations of PCDD/Fs declined with increasing trophic level. Principal Component Analysis (PCA) also showed differences between species in the pattern of PCDD/Fs. Higher chlorinated congeners constituted lower percentages of the PCDD/F-concentrations higher in the food chain as compared to lower trophic levels. In general, congener patterns did not differ between fjords. Infauna (polychaetes) and zooplankton had congener patterns most similar to the pollution source. The results indicate lower accumulation of higher chlorinated congeners in species at higher trophic levels (fish), presumably due to low membrane permeability (high molecular size) and possibly slow transport through intestinal aqueous phases because of low aqueous solubility.     

Complex cardiac defect with hypoplastic right ventricle in a fetus with valproate exposure

We describe a fetus with a hypoplastic right ventricle detected by prenatal ultrasound examination. A possible causal relationship with prenatal valproate exposure is discussed. Copyright © 2005 John Wiley & Sons, Ltd.     

Organotin compounds in a Norwegian fjord. A comparison of concentration levels in semipermeable membrane devices (SPMDs), blue mussels (Mytilus edulis) and water samples

Monitoring concentrations of organic pollutants in water is essential to predict effects and to initiate preventive steps. Results from the analysis of water samples provide snapshots of a situation, whereas monitoring using semipermeable membrane devices (SPMDs) provides a time-integrated picture of the concentration of pollutants in water. In this investigation, SPMDs, caged mussels and water samples were used to monitor the levels of organotin compounds in the inner Oslofjord, Norway, over a period of 12 weeks. The work-up procedure for the analysis of organotins was optimised, focusing on the clean-up procedure using gel permeation chromatography (GPC). By using several GPC columns, as much as 1 g of triolein could be employed. This reduces the background emission noise on the baseline, leading to an improvement in the detection limits. The main uptake of tributyltin (TBT) in mussels and SPMDs levelled off after 14 days. A longer uptake period was indicated for SPMDs at stations with a high water concentration of TBT (5-10 ng Sn L(-1)) compared with those with a low water concentration of TBT (approximately 1 ng Sn L(-1)). A concentration gradient was observed for water, SPMDs and mussels from the innermost station close to Oslo harbour to the station further out in the fjord, indicating that the three analysed matrices give approximately the same pollution gradient. The bioconcentration factor (BCF) for TBT in mussels was in the range 12-14 000 (wet weight) and, for SPMDs, 10-12 000 (fat). A good correlation with the TBT water concentrations was achieved within a period of 14-30 days of exposure for mussels and after 2-3 months for SPMDs. A good correlation was also found between the TBT concentration in SPMDs and mussels at the end of the experiment. SPMDs can therefore be used to predict concentrations of TBT in both water and mussels.     

Organotins in marine mammals and seabirds from Norwegian territory

An increasing number of studies indicate that marine mammals and some seabirds are exposed to organotins. However, results from northern and Arctic areas are few. Here results from analysis of tributyltin (TBT), dibutyltin (DBT), monobutyltin (MBT), triphenyltin (TPhT), diphenyltin (DPhT) and monophenyltin (MPhT) in harbour porpoise (Phocoena phocoena), common seal (Phoca vitulina), ringed seal (Phoca hispida) and glaucous gull (Larus hyperboreus) from Norwegian territory are presented. Relatively high concentrations of DBT, TBT and MBT were observed in muscle, kidney and liver from harbour porpoises caught in northern Norway in 1988, just before restrictions on the use of tributyltin (TBT)(mainly on small boats) were introduced in several European countries. The concentrations in harbour porpoise muscle tissue were reduced significantly 11 years later, possibly as a result of the introduced restrictions. Considerably lower concentrations of butyltins were observed in the seals compared to porpoises. The lowest levels of organotins were found in ringed seals from Spitsbergen, where only traces of dibutyltin (DBT) and monobutyltin (MBT) were observed. Traces of DBT and MBT were also found in some individual glaucous gulls from Bear Island. The sum of the degradation products MBT and DBT in liver samples from all analysed species were generally higher than TBT itself. Triphenyltin (TPhT) was observed in all porpoise samples and in livers of common seals. Also the sum of the degradation products MPhT and DPhT in liver samples from porpoise and common seals were higher than TPhT. No traces of phenyltins were found in ringed seals from Spitsbergen or in glaucous gulls from Bear Island. The limited data available indicate low to moderate exposure to organotins in northern areas (Spitsbergen and Bear Island). Marine mammals are however more exposed further south along the Norwegian Coast.     

Determinants of brominated flame retardants in breast milk from a large scale Norwegian study

Brominated flame retardants (BFRs), particularly polybrominated diphenyl ethers (PBDEs), are widely present in human populations. In order to investigate human exposure pathways and associations with socioeconomic and lifestyle factors, 393 breast milk samples from mothers living in various regions throughout Norway were analyzed. Up to ten PBDE congeners were measured in all the samples, hexabromocyclododecane (HBCD) and BDE-209 in subsets of 310 and 46, respectively. The median concentrations of the sum of the seven most prominent PBDEs (BDE-28, 47, 99, 100, 153, 154 and 183), BDE-209 and HBCD were 2.1, 0.32 and 0.86 ng/g lipids, respectively. These concentrations are comparable to the levels generally observed in human populations in Europe. The frequency distributions were quite skewed with long tails towards higher concentrations. Maternal age, parity, education, having a cohabitant employed as electrician, and ventilation were factors significantly associated with some of the BFRs, although these factors only explained a small amount of the variability (R² 0.04–0.16). The mothers' diet was not found to influence the breast milk PBDE and HBCD levels. Our results show that sources other than the diet are important for the variability seen in breast milk BFR concentrations and that exposure from the indoor atmosphere should be emphasized in future studies.     

Smallholder Farms as Stepping Stone Corridors for Crop-Raiding Elephant in Northern Tanzania: Integration of Bayesian Expert System and Network Simulator

Crop-raiding elephants affect local livelihoods, undermining conservation efforts. Yet, crop-raiding patterns are poorly understood, making prediction and protection difficult. We hypothesized that raiding elephants use corridors between daytime refuges and farmland. Elephant counts, crop-raiding records, household surveys, Bayesian expert system, and least-cost path simulation were used to predict four alternative categories of daily corridors: (1) footpaths, (2) dry river beds, (3) stepping stones along scattered small farms, and (4) trajectories of shortest distance to refuges. The corridor alignments were compared in terms of their minimum cumulative resistance to elephant movement and related to crop-raiding zones quantified by a kernel density function. The “stepping stone” corridors predicted the crop-raiding patterns. Elephant presence was confirmed along these corridors, demonstrating that small farms located between refuges and contiguous farmland increase habitat connectivity for elephant. Our analysis successfully predicted elephant occurrence in farmland where daytime counts failed to detect nocturnal presence. These results have conservation management implications.