Gaseous ammonia uptake in compost biofilters as related to compost water content

Sewage sludge and yard waste compost were used as biofilter materials and tested with respect to their capacity for removing ammonia from air at different water contents. Ammonia removal was measured in biofilters containing compost wetted to different moisture contents ranging from air dry to field capacity (maximum water holding capacity). Filters were operated for 15 days and subsequently analyzed for NH3/NH4+, NO2-, and NO3-. The measured nitrogen species concentration profiles inside the filters were used to calculate ammonia removal rates. The results showed that ammonia removal is strongly dependent on the water content in the filter material. At gravimetric water contents below 0.25 g H2O g solids(-1) for the yard waste compost and 0.5 g H2O g solids(-1) ammonia removal rates were very low but increased rapidly above these values. The sewage sludge compost filters yielded more than twice the ammonia removal rate observed for yard waste compost likely because of a high initial concentration of nitrifying bacteria originating from the wastewater treatment process and a high airwater interphase surface area that facilitates effective ammonia dissolution and transport to the biofilm.     

A novel use of anaerobically digested liquid swine manure to potentially control soybean cyst nematode

Experiments were carried out in two steps to determine the effect of anaerobically digested swine manure on soybean cyst nematode (SCN) egg control. In the first step, liquid swine manure underwent anaerobic digestion to search for the best digestion time for both volatile fatty acids (VFA) and ammonium nitrogen (NH(4)(+)) enrichment. The results showed that about 17 and 28 days of incubation were needed, respectively, to reach the maximal levels of VFA and NH(4)(+) in the manure. In the second step, raw, VFA-enriched, and NH(4)(+)-enriched manure were applied separately, at four different rates (25, 50, 100, and 200 mL/pot), to soil pots inoculated with nematode eggs in a greenhouse environment. Soil samples were collected 35 and 61 days after inoculation to determine the effect of such treated manure on SCN egg productivity. The data indicated that the SCN egg counts were inversely related to the manure application rates in a linear manner with correlation coefficients of 0.998, 0.967, and 0.900 for raw, NH(4)(+)-enriched, and VFA-enriched manure for the 35-day samples. While no such relationships were found for the 61-day samples, implying that none of the treatments were still effective 61 days after application. At the four application rates, the VFA-enriched manure performed best in reducing SCN egg counts (by 18.1, 19.5, 34.3, and 18.6%) as compared to the raw manure treatment. In contrast, the NH(4)(+)-enriched manure achieved mostly negative reductions. To achieve the best control of SCN egg growth, the VFA-enriched manure should be used and applied to soybean fields every 35 days.     

The post‐disaster negative health legacy: pregnancy outcomes in Louisiana after Hurricane Andrew

Disasters and displacement increasingly affect and challenge urban settings. How do pregnant women fare in the aftermath of a major disaster? This paper investigates the effect of pregnancies in disaster situations. The study tests a hypothesis that pregnant women residing in hurricane‐prone areas suffer higher health risks. The setting is Louisiana in the Gulf Coast, United States, a state that continually experiences hurricane impacts. The time period for the analysis is three years following the landfall of Hurricane Andrew in 1992. We analysed low birth weight and preterm deliveries before and after landfall, as a whole and by race. Findings support an association between hazards and health of a community and indicate that pregnant women in the affected area, irrespective of race, are more likely to experience preterm deliveries compared to pre‐event births. Results suggest there is a negative health legacy impact in Louisiana as a result of hurricane landfall.     

Application of multiple-population viability analysis to evaluate species recovery alternatives

Population viability analysis (PVA) is a powerful conservation tool, but it remains impractical for many species, particularly species with multiple, broadly distributed populations for which collecting suitable data can be challenging. A recently developed method of multiple-population viability analysis (MPVA), however, addresses many limitations of traditional PVA. We built on previous development of MPVA for Lahontan cutthroat trout (LCT) (Oncorhynchus clarkii henshawi), a species listed under the U.S. Endangered Species Act, that is distributed broadly across habitat fragments in the Great Basin (U.S.A.). We simulated potential management scenarios and assessed their effects on population sizes and extinction risks in 211 streams, where LCT exist or may be reintroduced. Conservation populations (those managed for recovery) tended to have lower extinction risks than nonconservation populations (mean = 19.8% vs. 52.7%), but not always. Active management or reprioritization may be warranted in some cases. Eliminating non-native trout had a strong positive effect on overall carrying capacities for LCT populations but often did not translate into lower extinction risks unless simulations also reduced associated stochasticity (to the mean for populations without non-native trout). Sixty fish or 5–10 fish/km was the minimum reintroduction number and density, respectively, that provided near-maximum reintroduction success. This modeling framework provided crucial insights and empirical justification for conservation planning and specific adaptive management actions for this threatened species. More broadly, MPVA is applicable to a wide range of species exhibiting geographic rarity and limited availability of abundance data and greatly extends the potential use of empirical PVA for conservation assessment and planning.     

Biohydrogen production through fermentation using liquid swine manure as substrate

In this paper, continuous production of hydrogen through fermentation with liquid swine manure as substrate was researched using a semi-continuously fed fermenter (8 L in total volume and 4 L in working volume). The pH and temperature for the fermenter were controlled at 5.3 ± 0.1 and 35 ± 1°C, respectively, throughout the experiment. Three hydraulic retention times (16, 20, and 24 h) were investigated for their impact on the efficiency and performance of the fermenter in terms of hydrogen yields. The results indicate that hydraulic retention time (HRT) has a strong influence on the fermenter performance. An increasing HRT would increase the variation in hydrogen concentration in the offgas. To produce hydrogen with a fairly consistent concentration, the HRT of the fermenter should not exceed 16 h, which, however, did not appear to be short enough to control methanogenesis because the offgas still contained about 5% methane. When methane content in the offgas exceeded 2%, an inverse linear relationship between hydrogen and methane was observed with a correlation coefficient of 0.9699. To increase hydrogen content in the offgas, methane production has to be limited to below 2%. Also, keeping oxygen content in the fermenter below 1.5% would increase the hydrogen concentration to over 15%. The product to substrate ratio was found to be around 50% for the fermenter system studied, evidenced by the observation that for every 6 liters of manure fermented, 3 liters of pure hydrogen were produced, which was significant and encouraging.     

Manure application technology in reduced tillage and forage systems: a review

Managing manure in reduced tillage and forage systems presents challenges, as incorporation by tillage is not compatible. Surface-applied manure that is not quickly incorporated into soil provides inefficient delivery of manure nutrients to crops due to environmental losses through ammonia (NH3) volatilization and nutrient losses in runoff, and serves as a major source of nuisance odors. An array of technologies now exist to facilitate the incorporation of liquid manures into soil with restricted or minor soil disturbance, some of which are new: shallow disk injection; chisel injection; aeration infiltration; pressure injection. Surface banding of manure inforages decreases NH3 emissions relative to surface broadcasting, as the canopy can decrease wind speed over the manure, but greater reductions can be achieved with manure injection. Soilaeration is intended to hasten manure infiltration, but its benefits are not consistent and may be related to factors such as soildrainage characteristics. Work remains to be done on refining its method of use and timing relative to manure application, which may improve its effectiveness. Placing manure under the soil surface efficiency by injection offers much promise to improve N use efficiency through less NH3 volatilization, reduced odors and decreased nutrient losses in runoff, relative to surface application. We identified significant gaps in our knowledge as manyof these technologies are relatively new, and this should help target future research efforts including environmental, agronomic, and economic assessments.     

Mobilisation capacity for agri-environmental management

The integration of environmental concerns into agricultural policies - through agri-environment measures (AEM) - has seen a fast development across Europe. This paper conceives AEM as an evolving instrument, a product that takes shape, gets diffused and taken up in, by and through networks of relations. Success then depends on the mobilisation or active participation of all those who may support and develop it. Using the examples of the Flanders' and Walloon regions of Belgium, the paper sets out to examine the mechanisms by which mobilisation for agri-environmental management develops, and by doing so, to gain a better understanding of mobilisation capacity as a concept to be used for evaluating policy implementation in this area. The study follows AEM along the various trajectories of implementation (design, distribution, application). The findings reveal how mobilisation capacity is gradually built-up by the interplay between AEM and the networks it connects to. The case illustrates well how such interactions occur all the way from administration offices to farmers' fields, and that their nature can be very different (e.g., formal and informal, durable and short-lived, expected and unexpected). It is concluded that in evaluating actor-networks, one should look at them in an open and fluid manner, that is, not to privilege any particular configuration or form of attachment over the other, not take intentions and objectives as a starting point but instead address the opportunities for synergies, and be aware that any network built around the instrument may change its content and the way it functions.     

Mercury trends in fish from rivers and lakes in the United States, 1969�C2005

A national dataset on concentrations of mercury in fish, compiled mainly from state and federal monitoring programs, was used to evaluate trends in mercury (Hg) in fish from US rivers and lakes. Trends were analyzed on data aggregated by site and by state, using samples of the same fish species and tissue type, and using fish of similar lengths. Site-based trends were evaluated from 1969 to 2005, but focused on a subset of the data from 1969 to 1987. Data aggregated by state were used to evaluate trends in fish Hg concentrations from 1988 to 2005. In addition, the most recent Hg fish data (1996?C2005) were compared to wet Hg deposition data from the Mercury Deposition Network (MDN) over the same period. Downward trends in Hg concentrations in fish from data collected during 1969?C1987 exceeded upward trends by a ratio of 6 to 1. Declining Hg accumulation rates in sediment and peat cores reported by many studies during the 1970s and 1980s correspond with the period when the most downward trends in fish Hg concentrations occurred. Downward Hg trends in both sediment cores and fish were also consistent with the implementation of stricter regulatory controls of direct releases of Hg to the atmosphere and surface waters during the same period. The southeastern USA had more upward Hg trends in fish than other regions for both site and state aggregated data. Upward Hg trends in fish from the southeastern USA were associated with increases in wet deposition in the region and may be attributed to a greater influence of global atmospheric Hg emissions in the southeastern USA. No significant trends were found in 62% of the fish species from six states from 1996 to 2005. A lack of Hg trends in fish in the more recent data was consistent with the lack of trends in wet Hg deposition at MDN sites and with relatively constant global emissions during the same time period. Although few significant trends were observed in the more recent Hg concentrations in fish, it is anticipated that Hg concentrations in fish will respond to changes in atmospheric Hg deposition, however, the magnitude and timing of the response is uncertain.