Plant-available and water-soluble phosphorus in soils amended with separated manure solids

Physical, chemical, or biological treatment of animal liquid manure generally produces a dry-matter rich fraction (DMF) that contains most of the initial phosphorus (P). Our objective was to assess the solubility and plant availability of P from various DMFs as a function of soil P status. Eight different DMFs were obtained from liquid swine (LSM) and dairy cattle (LDC) manures treated by natural decantation, anaerobic digestion, chemical flocculation, composting, or mechanical separation. The DMFs were compared with mineral P fertilizer in a pot experiment with oat ( L.) grown in four soils with varied P-fixing capacities and P saturation levels. The DMFs were added at a rate of 50 mg P kg soil and incubated 14 d before seeding. Soil water-extractable P (P) at all water:soil extraction ratios (2:1, 20:1, and 200:1) was slightly higher when DMFs were derived from LDC rather than LSM. Soil P at the 2:1 ratio was lower with anaerobically digested LSM. At the 2:1 extraction ratio, DMF P was less soluble than mineral P as P saturation in soils increased. In soils with a lower P-fixing capacity, DMF P appeared less water soluble than mineral P under 20:1 and 200:1 extraction ratios. After 72 d of plant growth, DMFs produced yields comparable to mineral P fertilizer. Although the plant availability of P from DMFs was comparable to mineral P fertilizer, P from DMFs could be less vulnerable to leaching or runoff losses in soils with a high P saturation level or low P-fixing capacity.     

Uptake and effects of copper and cadmium in the gonad of the scallop Placopecten magellanicus: concurrent metal exposure

Sea scallops Placopecten magellanicus in early gametogenesis from the southern shelf of Hudson Canyon, New Jersey, USA, were exposed in late winter 1984 to sublethal levels of Cu and Cd in a flowing seawater system at the NMFS Milford Laboratory. Exposure was to copper (10 and 20 gl^-1: low-Cu and high-Cu groups) or to a combination of copper and equimolar cadmium (10g Cu+17.7 g Cdl^-1: low-Cu/Cd group) for eight weeks, with sampling at 2-wk intervals. Copper had a strongly inhibitory effect on gamete production and maturation, which in some respects was partially moderated in the presence of cadmium in the female gonad only. Total gamete weight per scallop doubled in control individuals but dropped by 60% in both high-metal exposure groups over the 8-wk exposure period, with a smaller, temporary decrease in the low-Cu group. Cadmium did not add to the inhibition by copper of gamete development in the low-Cu/Cd group, but there was no partial recovery at 8 wk, as was seen in female scallops exposed to low-Cu alone. Gonadal RNA, higher in the females, decreased proportionately more in that sex than in the males of the metal exposure groups. Conversely, DNA levels were higher in the male than in the female gonad, and decreased sharply in all metal-exposed males. Gonadal protein concentration also dropped in all metal-exposed scallops with time and degree of metal exposure. Copper uptake in the gonad increased with time and metal exposure concentration, and cadmium increased in the low-Cu/Cd group with time. In contrast, manganese decreased significantly in the gonads of Cu-exposed scallops, especially in the high-Cu group. In the low-Cu/Cd group, manganese concentrations stabilized after an initial sharp drop at 2 wk in the low-Cu/Cd group, then rose at 6 and 8 wk. We ascribe this phenomenon to the induction by cadmium of metal-binding proteins (Fowler and Megginson 1986). In both sexes, gonadal magnesium concentrations did not change with increasing tissue burdens of copper and cadmium, but instead rose initially in proportion to the degree of metal exposure, homeostasis being maintained thereafter.     

Pathway of CH4 formation in anoxic rice field soil and rice roots determined by 13C-stable isotope fractionation

In anoxic rice fields methane is produced by either reduction of CO2 or cleavage of acetate. We measured the delta 13C-values of CH4 and CO2, acetate and organic carbon during time course experiments with anoxic methanogenic soil and root samples and used these values to calculate the fractions of CH4 (and acetate) produced from CO2 reduction. Comparison with radiotracer and/or inhibitor studies constrained the kinetic fractionation factors used for calculation. The fractionation factors for the conversion of CO2 to CH4 and of acetate to CH4 were on the order of alpha = 1.07 (epsilon = -70%) and epsilon > or = - 20%, respectively. The pathway of CH4 production changed with time of anoxic incubation. Anoxic slurries of rice field soil first produced CH4 predominantly (>50%) from CO2, then predominantly (>80%) from acetate and finally (after about one month) according to the theoretically expected ratio (33% CO2 and 67% acetate). Anoxic rice roots, on the other hand, initially produced CH4 exclusively from CO2, followed by contribution of acetate of about 40-60%. Rice roots also produced acetate that partially originated (< or = 1 30%) from reduction of CO2 as determined by calculation of isotopic fractionation using fractionation factors from the literature. The results demonstrate that there is quite some variability in pathways of CH4 production, and also indicate that isotopic fractionation factors may be different in different habitats and change with time.     

Photoactive titanium dioxide nanoparticles modify heterotrophic microbial functioning

Environmental Science and Pollution Research - Nanoparticulate titanium dioxide (nTiO2) is frequently applied, raising concerns about potential side effects on the environment. While various...     

Free Energy Reduction by Molecular Interface Crossing: Novel Mechanism for the Transport of Material Across the Interface of Nanoscale Droplets Induced by Competing Intermolecular Forces for Application in Perfluorocarbon Blood Substitutes

 Perfluorocarbons (PFCs) are inert liquids which can dissolve – and release – approximately 50 times more oxygen than blood plasma. Oxygen carriers based on PFCs are easy to produce, free of biological components, and more rigorously sterilizable than blood. PFCs injected into the body are eliminated by expiration through the lungs. Before reaching the lungs, PFCs accumulate in storage organs such as liver and spleen. In these organs nanoscale PFC droplets reduce their free energy by unifying to microscopic drops, thus indirectly lowering the rate of their expiration. The model of free energy reduction by molecular interface crossing (FERMIC), a novel emulsion breaking mechanism derived from first principles as presented here, leads to a better understanding of the structure formation processes relevant in perfluorocarbons (PFCs) in vivo. Received: 11 November 1998 / Accepted in revised form: 18 February 1999     

Energy or compost from green waste? – A CO2 – Based assessment

Green waste is increasingly extracted from the material recycling chain and, as a result of the financial subsidy arising from the German renewable energy law for the generation of energy from renewable raw materials; it is fed into the energy recovery process in biomass power stations. A reduction in climate relevant gases is also linked to the material recovery of green waste – in particular when using composts gained from the process as a new raw material in different types of potting compost and plant culture media as a replacement for peat. Unlike energy recovery, material valorisation is not currently subsidised. Through the analysis of material and energy valorisation methods for green waste, with particular emphasis on primary resource consumption and CO₂-balance, it could be determined that the use of green waste for energy generation and its recovery for material and peat replacement purposes can be considered to be on a par. Based on energy recovery or material oriented scenarios, it can be further deduced that no method on its own will achieve the desired outcome and that a combination of recycling processes is more likely to lead to a significant decrease of greenhouse gas emissions.     

Fresh, stockpiled, and composted beef cattle feedlot manure: nutrient levels and mass balance estimates in Alberta and Manitoba

The fate of manure nutrients in beef cattle (Bos taurus) feedlots is influenced by handling treatment, yet few data are available in western Canada comparing traditional practices (fresh handling, stockpiling) with newer ones (composting). This study examined the influence of handling treatment (fresh, stockpiled, or composted) on nutrient levels and mass balance estimates of feedlot manure at Lethbridge, Alberta, and Brandon, Manitoba. Total carbon (TC) concentration of compost (161 kg Mg(-1)) was lower (P < 0.001) than stockpiled (248 kg Mg(-1)), which was in turn lower (P < 0.001) than fresh manure (314 kg Mg(-1)). Total nitrogen (TN) concentration was not affected by handling treatment while total phosphorus (TP) concentration increased with composting at Lethbridge. The percent inorganic nitrogen (PIN) was lower (P < 0.01) for compost (5.1%) than both fresh (24.7%) and stockpiled (28.9%) manure. Composting led to higher (P < 0.05) dry matter (DM) losses (39.8%) compared to stockpiling (22.5%) and higher (P < 0.05) total mass (water + DM) losses (65.6 vs. 35.2%). Carbon (C) losses were higher (P < 0.01) with composting (66.9% of initial) than with stockpiling (37.5%), as were nitrogen (N) losses (46.3 vs. 22.5%, P < 0.05). Composting allowed transport of two times as much P as fresh manure and 1.4 times as much P as stockpiled manure (P < 0.001) on an "as is" basis. Our study looked at one aspect of manure management (i.e., handling treatment effects on nutrient concentrations and mass balance estimates) and, as such, should be viewed as one component in the larger context of a life cycle assessment.     

How prepared is prepared enough?

Decisions about disaster preparedness are rarely informed by cost‐benefit analyses. This paper presents an economic model to address the thorny question, ‘how prepared is prepared enough?’ Difficulties related to the use of cost‐benefit analysis in the field of disaster management concern the tension between the large number of high‐probability events that can be handled by a single emergency response unit and the small number of low‐probability events that must be handled by a large number of them. A further special feature of disaster management concerns the opportunity for cooperation between different emergency response units. To account for these issues, we introduce a portfolio approach. Our analysis shows that it would be useful to define disaster preparedness not in terms of capacities, but in terms of the frequency with which response capacity is expected to fall short.     

The costs and benefits of cooperation between the Australian lycaenid butterfly,Jalmenus evagoras,and its attendant ants

Summary The larvae and pupae of the Australian lycaenid butterfly, Jalmenus evagoras associate mutualistically with ants in the genus Iridomyrmex. Four ant exclusion experiments in three field sites demonstrated that predation and parasitism of J. evagoras are so intense that individuals deprived of their attendant ants are unlikely to survive. Larvae and pupae of J. evagoras aggregate, and the mean number of attendant ants per individual increases with larval age and decreases with group size. Field observations showed that young larvae could gain more attendant ants per individual by joining the average size group of about 4 larvae than by foraging alone. Aggregation behaviour is influenced by ant attendance: young larvae and pupating fifth instars aggregated significantly more often on plants with ants than on plants where ants had been excluded. In return for tending and protecting the larvae, ants were rewarded by food secretions that can amount to as much as 409 mg dry biomass from a single host plant containing 62 larvae and pupae of J. evagoras over a 24 h period. Larval development in the laboratory lasted approximately a month, and larvae that were tended by ants developed almost 5 days faster than larvae that were not tended. However, tended individuals, particularly females, pupated at a significantly lower weight than their untended counterparts, and the adults that eclosed from these pupae were also lighter and smaller. On average, pupae that were tended by ants lost 25% more weight than untended pupae, and in contrast with larvae, they took longer to eclose than pupae that were not tended. These experimental results are discussed in terms of costs and benefits of association for both partners, and of aggregation for the lycaenids.