Spatial variability of organic matter degradability in tidal Elbe sediments

Purpose

The microbial turnover of sediment organic matter (OM) in ports and waterways impacts water quality, sonic depth finding and presumably also rheological properties as well as greenhouse gas emissions, especially if organic carbon is released as methane. As a consequence, sediment management practices as a whole are affected. This study aimed to discern spatial OM degradability patterns in the Port of Hamburg and investigated correlations with standard analytical properties as a basis for future predictive modelling.

Materials and methods

Sediments in the Port of Hamburg were repeatedly sampled at nine locations along an east-west transect using a 1-m corer. In a stratified sampling approach, layers of suspended particulate matter (SPM), fluid mud (FM), pre-consolidated sediment (PS) and consolidated sediment (CS) were identified and individually analysed for long-term aerobic and anaerobic degradation of organic matter, DNA concentration, stable carbon isotope signature, density fractions and standard solids and pore water properties.

Results and discussion

The investigation area was characterised by a distinct gradient with a 10-fold higher OM degradability in upstream areas and lower degradability in downstream areas. Concomitantly, upstream locations showed higher DNA concentrations and more negative δ¹³C values. The share of bulk sediment in the heavy density fraction as well as the proportion and absolute amount of organic carbon were significantly larger at downstream locations. A depth and hence age-related gradient was found at individual locations, showing higher degradability of the upper, younger material, concomitant with higher DNA concentration, and lower OM turnover in the deeper, older and more consolidated material. Deeper layers were also characterised by higher concentrations of pore water ammonium, indicative of anaerobic nitrogen mineralisation.

Conclusions

Organic matter lability is inversely linked to its stabilisation in organo-mineral complexes. The observed degradability gradient is likely due to the different OM quality in relation to its origin. Downstream OM enters the system with the tidal flood current from the direction of the North Sea whereas upstream locations receive OM originating from the catchment, containing more autochthonous, plankton-derived and more easily degradable components. At individual sampling points, depth-related degradability gradients reflect an age gradient, with easily degradable material in top layers and increasing stabilisation of OM in organo-mineral compounds with depth.

     

Effect of source and quantity of dietary vitamin D in maternal and creep diets on bone metabolism and growth in piglets

Piglets are born with reduced plasma concentrations of 25-hydroxycholecalciferol (25-OH-D(3)) and are thus highly predisposed to vitamin D deficiency. Furthermore, sow milk contains little vitamin D, and the slow intestinal vitamin D absorption of sows limits the efficacy of dietary vitamin D supplementation. Hence, the neonate depends, to a large extent, on the vitamin D stores built up in fetal tissues from maternal sources. The current study was undertaken to evaluate whether the source and quantity of dietary vitamin D provided to the gestating and lactating sow, and also directly in the form of creep feed to the piglet, would influence the vitamin D status, growth performance, and skeletal development of piglets. A total of 39 primiparous and multiparous sows were randomly assigned to 1 of 3 dietary treatments (13 in each treatment), supplemented with either 5 or 50 μg of the commonly used cholecalciferol (vitamin D(3)) or 50 μg of 25-OH-D(3) per kilogram of feed. By wk 3 of lactation, piglets were offered a creep diet with vitamin D supplementation according to the treatment of the dam, and they were offered the same creep diets after weaning at d 35 of age until they reached a BW of approximately 20 kg. When dietary 25-OH-D(3) was provided, circulating concentrations of 25-OH-D(3) in piglet serum increased (P < 0.05) as early as d 21 and later at d 33 and 77, indicating greater body stores in those animals. Bone-breaking strength and cortical bone mineral content and density at the tibial midshaft of piglets were reduced (P < 0.05) when vitamin D(3) was supplemented at 5 μg/kg compared with the bone traits of other groups, but no differences (P > 0.05) were observed between the 2 other groups. After weaning, ADFI was greater (P < 0.05) and growth performance tended (P = 0.08) to improve when doses of 50 μg/kg were administered, regardless of the vitamin D source. In conclusion, supplementation of the diet with 50 μg/kg of either source of vitamin D was proved to be adequate in meeting the needs of gestating sows and in permitting the accumulation of vitamin D in fetal tissues, as well as for normal skeletal mineralization and growth in the offspring. Furthermore, the markedly improved vitamin D status of piglets whose mothers received 25-OH-D(3) possibly resulted from greater tissue reserves present at birth and a greater availability of vitamin D when released from those stores.     

Growth performance, energy, and nitrogen balance of weanling pigs fed a cereal-based diet supplemented with Chinese rhubarb

Forty Swiss Large White piglets of 4 weeks of age were used to determine the effect of dietary Chinese rhubarb on growth performance, as well as on energy and nitrogen metabolism by means of indirect respiration calorimetry studies. A cereal-based diet, supplemented with four different dosages of Chinese rhubarb (0.0%, 0.25%, 0.5%, 1%), was offered ad libitum to the piglets. Gaseous exchange was measured, and urine, faeces, and blood samples were taken. The addition of 0.25% dietary rhubarb increased feed intake (+32%) and daily weight gain (+67%) compared to the diet containing the greatest amount of rhubarb (1%). The piglets fed diet supplemented with 0.25% rhubarb digested and metabolised more energy and nitrogen relative to the animals of treatment 1%. As a consequence, the same group (0.25%) converted more energy and nitrogen into body protein than piglets receiving diet supplemented with 1% rhubarb. However, compared to the control group, the addition of 0.25% rhubarb to the diet resulted in not significantly alter growth performance, energy, and nitrogen metabolism of the animals.Blood parameters were not affected by the rhubarb supplementation. The dose-responding effect of Chinese rhubarb was reflected by the dry matter content of faecal samples. According to the laxative effect of higher doses of rhubarb, the addition of 1% rhubarb to the diet reduced dry matter content of faeces. This effect was well visible in practice, although not relevant in statistical terms. The addition of 0.5% dietary rhubarb had no relevant effect on growth performance or on energy and nitrogen metabolism of treated animals.     

Untersuchungen zum Nahrungseintrag von Kohlmeisen in einem Gradationsgebiet der Kleinen Fichtenblattwespe (Pristiphora abietina Christ)

Using a modern data survey system combined with a videocamera for observation, it was possible to determine the percentage of sawfly larvac in breeding food of titmouse (Parus major) without disturbing the birds. The activities of a titmouse pair in a spruce stand, located in southeast Bavaria and seriously damaged by spruce sawfly, were observed during the whole breeding period. Spruce sawfly larvae were used as breeding food preferably at 4th larvae instar or later. Since larvae of this instar were available, they dominated the insects used as breeding food with more than 70%. During the most intensive feeding period nearly 500 sawfly larvae per day were used as food. The consumption of sawfly larvae during the whole feeding period added up to a total of more than 5000 larvae. The birds can not significantly reduce the sawfly density in heavily attacked stands. This can be shown in a simple calculation: there had been 11 titmouse pairs per hectar. They used appr. 55000 old larvae for breeding food. This represents appr. 15% of the estimated number of old sawfly larvae per hectar. But in a low density area an insect-feeding songbird population may possibly hinder a serious increase in the sawfly population.     

Variability of methane emissions from an old landfill over different time‐scales

Methane (CH₄) emission patterns were investigated at an old landfill in northern Germany during a 2‐year campaign over three different time‐scales (seasonal, daily and diurnal) using modified static chambers. Emissions were not uniformly distributed over the cover soil, but occurred through localized preferential pathways (hotspots). The range of emissions from the 14 investigated hotspots at any one measurement event was large, reflecting large spatial variability of emissions from the landfill. In addition, the individual hotspots showed a large temporal variability of emissions (0–9.7 mol CH₄ day^?1 over a range of 20 months). Environmental variables effectively modified either the biological process of methane oxidation in the soil (temperature) or the physical gas transport process (moisture and atmospheric pressure). During the seasonal campaign, emissions generally were greater in winter (moister and cooler) and smaller during the summer period (dryer and warmer). Under dry conditions, emissions were independent of soil moisture but correlated negatively with soil temperature. A positive correlation of emissions with moisture was found for moisture levels relating to a matric potential of ?30 to ?6 kPa, reflecting impeded diffusive oxygen ingress and hence reduced methanotrophic activity. Under very moist conditions, more than ?6 kPa, emissions were negatively correlated with moisture content because of decreased gas permeability in the soil. In addition, a pressure decrease preceding the measurement was at all time‐scales often related to large emissions, whereas constant or rising pressure prior to measurement resulted in small emissions. The particular importance of the different effects depends on the type of gas transport at the specific emission location and whether it is advective or diffusive gas transport or a mixture of both, and varies at the temporal scale both between and within locations.     

Type C virus from cell cultures of chemically induced rat hepatomas

Type C RNA viruses are present in cell cultures from transplantable and primary hepatomas induced by aromatic amine carcinogens. Virus yield was markedly enhanced by treating the cells with bromodeoxyuridine. Preparations of rat hepatoma-associated virus obtained from cultures treated with this compound were deficient in DNA polymerase activity.     

Effect of dietary energy supply and fat source on the fatty acid pattern of adipose and lean tissues and lipogenesis in the pig

Forty Large White barrows were used to determine whether the effects of dietary fat source (tallow or soy oil at 5% of the diet) on lipogenesis and fatty acid profile of porcine adipose and lean tissue were dependent on dietary digestible energy density (8.8 vs 14.0 MJ DE/kg). Barrows were allocated to one of four groups and offered a fixed amount of feed (170 g x BW0.569/d) from 27 to 105 kg BW. The fatty acid composition of the backfat layers (BF), omental fat (OF), and i.m. adipose tissue of longissimus muscle as well as the activity of lipogenic enzymes of the adipose tissues were determined. Growth performance and carcass characteristics were affected by the dietary energy level (P < 0.01) but not by fat source. In accordance with the lower carcass fat deposition, the activity of lipogenic enzymes were decreased in the low-energy groups (P < 0.01). Within dietary energy level, inclusion of soy oil resulted in increased proportion of PUFA that was compensated by decreased saturated (SFA) and monounsaturated fatty acid (MUFA) proportions (P < 0.01). The SFA changes accounted for 23 (BF) and 24% (OF) of the PUFA changes in the high-energy and 31 (BF) and 39% (OF) in the low-energy diets. The differences in the fatty acid proportions between the soy oil and tallow group were more pronounced in the low-energy groups (fat source x energy density interactions: P < 0.01). Pigs fed the soy oil, low-energy diet had decreased SFA (BF: 28%; OF: 30%) and MUFA (BF: 13%; OF: 19%) concentration, whereas PUFA concentration was increased (BF: 59%; OF: 88%) compared with pigs fed the soy oil, high-energy diet. However, in the tallow groups, pigs fed the low-energy diets had slightly decreased SFA (BF: 14%; OF: 12%) and relatively constant MUFA (BF: 3%; OF: 1%), whereas PUFA concentration increased (BF: 39%; OF: 62%) relative to pigs fed the tallow high-energy diet. Lipid content of the i.m. adipose tissue was decreased in the low-energy groups (P < 0.05). Contrary to what was observed in the adipose tissues, increased PUFA concentration in the neutral and polar lipid fractions of the longissimus muscle was predominantly compensated by reduced MUFA deposition. In the polar lipid fraction, the proportions of both SFA and MUFA were decreased by the low-energy diet. Thus, the extent to which tissue concentration of fatty acids are altered from dietary fats differing in the degree of unsaturation depends on the dietary energy level.     

Quantifying Microbial Methane Oxidation Efficiencies in Two Experimental Landfill Biocovers Using Stable Isotopes

Stable isotope analyses were performed on gas samples collected within two instrumented biocovers, with the goal of evaluating CH₄ oxidation efficiencies (f ₀). In each of the biocovers, gas probes were installed at four locations and at several depths. One of the biocovers was fed with biogas directly from the waste mass, whereas the other was fed through a gas distribution system that allowed monitoring of biogas fluxes. While the f ₀ values obtained at a depth of 0.1 m were low (between 0.0% and 25.2%) for profiles with poor aeration, they were high for profiles with better aeration, reaching 89.7%. Several interrelated factors affecting aeration seem to be influencing f ₀, including the degree of water saturation, the magnitude of the biogas flux and the temperature within the substrate. Low f ₀ values do not mean necessarily that little CH₄ was oxidized. In fact, in certain cases where the CH₄ loading was high, the absolute amount of CH₄ oxidized was quite high and comparable to the rate of CH₄ oxidation for cases with low CH₄ loading and high f ₀. For the experimental biocover for which the CH₄ loading was known, the oxidation efficiency obtained using stable isotopes (f ₀?=?55.67% for samples taken inside flux chambers) was compared to the value obtained by mass balance (f ₀?=?70.0%). Several factors can explain this discrepancy, including the high sensitivity of f ₀ to slight changes in the isotopic fractionation factor for bacterial oxidation, α _ox, uncertainties related to mass flow metre readings and to the static chamber method.     

Additional data on energy requirements of young adult cats measured by indirect calorimetry

Measurements of nitrogen, carbon and energy balances were done on eight female adult cats aged approximately 1.5 years with the help of respiration chambers. The cats were fed with a marked dry food for kittens (Biomill kitten). Faeces and urine samples were collected with the help of a special cat toilet that allows the single collection of both materials. The calculated energy requirement of these eight female cats was 239.6 kJ ME/kg BW/day (R(2) = 0.98). Including the data, on 12 young male adult cats, of L?uger, (2001), an energy requirement of 238 kJ ME/kg BW/day (R(2) = 0.95) could be calculated. From these data, it can be followed that the energy requirements of young, active cats are higher than that of the older cats. The method of indirect calorimetry does not necessarily lead to lower energy requirements.     

Phytase and vitamin E in the feed of growing pigs: 2. Influence on carcass characteristics, meat and fat quality

Lipid oxidation is one of the the major causes of deterioration in the quality of meat and meat products. In addition to its nutrition value, meat has other aesthetic attributes, including its attractive sensory properties and therefore, lipid oxidation in meat and adipose tissue is undesirable. It can be reduced by the addition of antioxidants to feeds. Vitamin E functions is a lipid-soluble antioxidant in the cell membranes. One of the most potent forms is α-tocopherol. It is capable of quenching free radicals and thus protects susceptible cellular structures, especially polyunsaturated fatty acids in cell membranes, against oxidation and subsequent breakdown to potentially harmful, chemically reactive products (Packer and Fuchs 1993). Vitamin E supplementation above the physiological demand enhances the vitamin E concentration in tissue samples, milk and eggs (Leonhardt et al. 1997). Furthermore a positive effect on the various quality criteria of products of animal origin such as shelf life, colour, taste, etc. can be realized to meet the expectations of consumers (Asghar et al. 1991b; King et al. 1995). In another article it was demonstrated that supplementing diets with phytase had a positive effect on the digestibility of minerals such as phosphorus, calcium, iron and zinc (Gebert et al. 1999). The results indicated that dietary fat digestibility was significantly decreased due to the phytase supplementation. In addition, the α-tocopherol digestibility had a tendency to be impaired in the phytase- or vitamin E (200 p.p.m. α-tocopheryl acetate)-supplemented diets, indicating that the released minerals of the phytic acid complex could act as bi- and trivalent cations and might damage those nutrients which are susceptible to oxidation (mainly polyunsaturated fatty acids) or could use up the antioxidative vitamins in the digesta. Therefore it was of interest to investigate the effect of phytase and vitamin E (α-tocopheryl acetate) supplementation in pig diets on the carcass characteristics as well as meat and fat quality, mainly with respect to stability against oxidative destruction.