Production and carrying capacity for the earthworm Lumbricus terrestris in culture

Approximately 8 h were required at 25°C for food to pass from mouth to anus in the earthworm Lumbricus terrestris. Gut load per unit transit appeared inversely related to nitrogen content; values of about 2 and 44 mg dry castings per 100mg dry worm were obtained with activated sludge and mineral soil, respectively. Production of biomass was greater in a substrate of activated sludge and loam relative to activated sludge and cellulose, despite higher concentrations of nitrogen in the latter. Optimum population density was about 8 earthworms (31 g live wt) in 1000cm³ 2:1 sludge:soil. Growth occurred at a maximum rate between 15 and 25°C. A yield of approximately 4% biomass (dry wt) was obtained on a mixture of activated sludge and loam, based on the content of organic matter present.     

Modeling scour and deposition in ephemeral channels after wildfire

The area burned by wildfire in the states of Arizona and New Mexico in the southwestern US has been increasing in recent years. In many cases, high severity burns have caused dramatic increases in runoff and sediment yield from burned watersheds. This paper describes the potential and limitations of the HEC6T sediment transport model to describe changes in channel scour and deposition following the Cerro Grande fire near Los Alamos, New Mexico. Following the fire, Pueblo Canyon, near Los Alamos, was subject to a peak flow two orders of magnitudes higher than any discharge in the 7-year period of record, and twice the initial post-fire estimate of the 100-year event. HEC6T requires that the limits of scour and deposition on a cross-section be specified prior to application. This was achieved by using geomorphologic principles, predicted post-burn hydrology and long-term estimates of channel change derived from air photos, to estimate post-fire channel widths. Because significant quantities of silt and clay were present in the runoff, erosion shear stress and erosion rate parameters for cohesive sediments had to be obtained experimentally. After a sensitivity analysis, an optimization routine was used to estimate the optimal model parameter values for sensitive parameters. HEC6T was able to accurately model the change in cumulative sediment volume change derived from Airborne Laser Swath Mapping (ALSM, often called Lidar) taken before and after the large post-fire event. One discrepancy between the HEC6T model prediction and the ALSM-estimated change was that the ALSM-estimated change showed the greatest amount of deposition in a portion of the canyon with increasing slope, which the HEC6T model did not predict. Any sediment transport model will predict increased sediment transport capacity with increasing energy slope, so that it was considered to be beyond the capability of any sediment transport model to predict this deposition. Therefore, HEC6T simulated the overall changes in scour and deposition within reasonable expectation of the capabilities of physically-based sediment transport modeling indicating that it is capable of modeling sediment transport in ephemeral channels following wildfire.     

Long-term isovolumetric leaching of aluminum from rocks during weathering: Implications for the genesis of saprolite

Isovolumetric geochemical analyses of 26 weathering profiles (saprolites) on crystalline rocks in Brazil and South Carolina indicate that, on average, Si and Al are leached from rocks in a long-terms molar ratio of 8.3. Hewever, with the exception of the Rio Negro River, the molar ratio of Si to Al in rivers draining these regions is about 100. If saprolites are still forming, the large discrepancy in Al mobilization between the saprolite record and modern river chemistry may be due to degassing of dissolved CO₂ from soil water entering streams with attendant increase in pH and Al precipitation. If saprolites are relic, the Rio Negro basin may be a model for the environmental conditions under which they form. These conditions are 1) low relief, 2) abundant rainfall and intense leaching and 3) organic rich soils which produce large concentrations of CO₂ and dissolved organic acids in the soil. Abundant rainfall maintains dilute soil water; large CO₂ pressure lowers pH; dissolved organic matter complexes Al (and Fe) and thus enhances the solubility of secondary clays. All of these effects hinder the precipitation of secondary weathering products and thus promote rock dissolution that is more nearly congruent. The problem with the Rio Negro model is to reconcile the low relief of the basin (which inhibits rapid groundwater movement) with the short contact time indicated by the diluteness of its chemistry.     

A comparison of reciprocating flow versus constant flow in an integrated, gravel bed, aquaponic test system

Murray cod, ^{Maccullochella peelii peelii}, and Green oak lettuce, Lactuca sativa, were used to test for differences between two aquaponic flood regimes; reciprocal flow (hydroponic bed was periodically flooded) and constant flow (hydroponic bed was constantly flooded), in a freshwater aquaponic test system, where plant nutrients were supplied from fish wastes, while plants stripped nutrients from the wastewater before it was returned to the fish. The Murray cod had FCRs and biomass gains that were statistically identical in both systems. Lettuce yields were good and a significantly greater amount of both biomass and yield occurred in the constant flow treatment. Constant flow treatments exhibited greater pH buffering capacity, required fewer bicarbonate (buffer) additions to control pH and maintained lower conductivity levels than reciprocal flow controls. Water consumption in the two systems was statistically identical. Overall, results suggest that a constant flow flooding regime is as good as, or better than, a reciprocating flooding regime in the aquaponic test system used.     

Method for determining the physical stability of shrimp feeds in water

Three methods for measuring the water stability and leaching characteristics of shrimp pelleted feeds were developed and tested: static water method, horizontal shaking method and vertical shaking method. Each method was tested using a commercial and experimental pelleted shrimp feed. Both feeds had a pellet size of 2.4 mm × 5.0 mm with similar proximate composition (35% protein and 9% fat). Each test run consisted of leaching c. 2 g of feed at six intervals of immersion time (0, 30, 60, 120, 240, 360 min), two concentrations of salinity (0, 34 ppt), and three different water temperatures (15, 25, 35 °C). A refrigerated circulating water bath was used to maintain the desired level of water temperature. For the static water and horizontal shaking methods, a Buchner filtration apparatus with Whatman filter paper no. 3 (5 μ) was used to separate the remaining pellets from leached water. The vertical shaking method (VanKel) utilized a perforated stainless‐steel basket (381 μ) for leaching and serving as a filter to separate pellets from leached water. For all three methods, the leached feed and original feed samples were dried in a convection oven at 105 °C for 24 h and then cooled in a desiccator. Dried feed samples were weighed and analysed for dry matter retention. Pellet stability was calculated as the ratio of dry matter retention after leaching and dry matter of original samples expressed as a percentage. Results indicated that any method for pellet stability analysis should take into account water temperature and salinity in addition to actual pellet agitation rate to obtain accurate and consistent measurement of pellet disintegration and nutrient leaching. Dry matter retention was different for each shrimp feed with experimental feed (72.8%) showing lower retention than commercial feed (88%) after 6 h of VanKel leaching under normal shrimp culture conditions. The three methods provided reproducible results with both horizontal and vertical shaking methods recommended for routine laboratory analysis because they could provide different degrees of pellet agitation that simulate actual indoor and outdoor shrimp culture conditions.     

Effects of feeding a high level of D-glucose on liver function in juvenile white sturgeon (Acipenser transmontanus)

Juvenile white sturgeon (Acipenser transmontanus) were fed three isonitrogenous and isoenergetic diets containing either 35% D-glucose (HC), a mixture of 20% dextrin and 10% cellulose (MC), or 23% cellulose (LC), to investigate the effects of dietary carbohydrate on liver function. After 8-week feeding, body weight gain of fish fed the HC diet was consistently higher than that of fish fed the MC and LC diets, but was not significantly different from the MC-fed fish. Fish fed the HC diet had significantly (p < 0.05) higher feed efficiencies and liver glycogen concentrations than fish fed the MC and LC diets. Sturgeon were injected intravenously with 10 mg kg^-1 body weight of sulfobromophthalein (BSP) and post-injection blood taken from the caudal vein at 15, 30, 60, and 120 min. No significant differences in plasma BSP concentrations were found among the treatments at these times. Plasma hemoglobin and activities of aspartate and alanine aminotransferase were not affected by the diets. This study suggests that the HC diet does not adversely affect liver function or weight gain. Inclusion of high dietary levels of digestible and inexpensive carbohydrates in commercial sturgeon feeds seems promising, but long-term feeding trials should be conducted to confirm this assertion.     

Chemical emissions from adhesive-bonded wood products at elevated temperatures

Pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) was employed to examine the chemical emissions from the glued wood samples at elevated temperatures (150, 200, 250, 300, 350, 400, 450, and 500°C). Two wood species, Douglas-fir (Pseudotsuga menziesii) and southern pine (Pinus palustris), one structural adhesive, phenol–resorcinol–formaldehyde (PRF), PRF-bonded Douglas-fir, and PRF-bonded southern pine were evaluated. The volatile compounds with a mass range of 35–300 m/z emitted from the pyrolysis samples were separated by gas chromatography (GC) and identified by mass spectrometry (MS). The results indicated that compared to neat wood and resin film samples, several additional pyrolysis products were observed for the PRF-bonded wood samples including (1) acetaldehyde and butanedial for PRF-bonded Douglas-fir and (2) acetaldehyde, furfural, 2-furanmethanol, butanedial, 2,3-butanedione, cyclopropyl carbinol, 1,2-benzenediol, and 1-(acetyloxy)-2-propanone for PRF-bonded southern pine. These additional compounds were possibly associated with the interaction between wood and PRF resin. The results also indicated that bonded wood products would be less thermally stable than those of neat wood and PRF resin samples.     

Gas chromatography-mass spectrometry determination of phosphine residues in stored products and processed foods

A gas chromatography-mass spectrometry (GC-MS) method was used for the quantitative confirmation of phosphine residues in stored products and processed foods. An established extraction technique was utilized for the preparation of headspace samples, which were analyzed by GC-MS and gas chromatography-nitrogen-phosphorus detection (GC-NPD). Wheat, oats, maize, white rice, brown rice, cornflakes, tortilla cornchips, groundnuts, and raisins were validated, showing excellent agreement between detectors when spiked at levels equivalent to 0.001 and 0.01 mg/kg phosphine and for samples containing incurred residues. The GC-MS method was reproducible and accurate when compared to the GC-NPD method and allowed five samples to be quantified in a working day. Subambient GC-MS oven temperatures were most suitable for phosphine residues ranging from 0.001 to 0.005 mg/kg, and a GC oven temperature of 100 degrees C was appropriate for residues >0.005 mg/kg. The method was sufficiently robust to be evaluated for other similar commodities as the need arises.     

Evaluation of the zoonotic potential of Giardia duodenalis in fecal samples from dogs and cats in Ontario

This study determined the distribution and zoonotic potential of Giardia duodenalis assemblage types among canine and feline fecal samples from Ontario. The effectiveness of Giardia assemblage typing methods by sequencing the genes of small subunit ribosomal RNA (ssu-rRNA), β-giardin (bg), glutamate dehydrogenase (gdh), and triose phosphate isomerase (tpi) was evaluated simultaneously. From 2008 to 2010, 118 canine and 15 feline Giardia positive fecal samples were tested. The ssu-rRNA sequencing method typed 64% (75/118) and 87% (13/15) of the Giardia-positive canine and feline samples, respectively. Among the typeable samples, 68% (51/75) of canine samples contained G. duodenalis assemblage D and 31% (23/75) contained G. duodenalis assemblage C (both non-zoonotic assemblage types). Only 1% (1/75) of the typeable canine samples contained a potentially zoonotic assemblage B. In contrast, 100% (13/13) of the typeable feline samples contained potentially zoonotic assemblages A (n = 12) or B (n = 1).