Anaerobic digestion produces a biologically stable and high-value fertilizer product, the digestate, which can be used as an alternative to mineral fertilizers on crops. However, misuse of digestate ...can lead to annoyance for the public (odours) and to environmental problems such as nitrate leaching and ammonia emissions into the air. Full field experimental data are needed to support the use of digestate in agriculture, promoting its correct management. In this work, short-term experiments were performed to substitute mineral N fertilizers (urea) with digestate and products derived from it to the crop silage maize. Digestate and the liquid fraction of digestate were applied to soil at pre-sowing and as topdressing fertilizers in comparison with urea, both by surface application and subsurface injection during the cropping seasons 2012 and 2013. After each fertilizer application, both odours and ammonia emissions were measured, giving data about digestate and derived products' impacts.
The AD products could substitute for urea without reducing crop yields, apart from the surface application of AD-derived fertilizers. Digestate and derived products, because of high biological stability acquired during the AD, had greatly reduced olfactometry impact, above all when they were injected into soils (82–88% less odours than the untreated biomass, i.e. cattle slurry). Ammonia emission data indicated, as expected, that the correct use of digestate and derived products required their injection into the soil avoiding, ammonia volatilization into the air and preserving fertilizer value. Sub-surface injection allowed ammonia emissions to be reduced by 69% and 77% compared with surface application during the 2012 and 2013 campaigns.
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•Anaerobic digestion produced useful fertilizers, i.e. the digestate.•Digestate misuses led to odours and ammonia impacts.•Pre-sowing and topdressing use of digestate substituted completely N-fertilizers.•Subsurface injection of digestate reduced greatly odour and NH3 emissions.•Digestate use allowed producing maize silage as well as using urea.
Scholars are increasingly calling for the environmental issues of the industrial agricultural system to be addressed via eventual agroecological system-level transformation. It is critical to ...identify the barriers to this transition. Drawing from Henke’s (Cultivating science, harvesting power: science and industrial agriculture in California, MIT Press, Cambridge, MA, 2008) theory of “repair,” we explore how farmers participate in the reproduction of the industrial system through “discursive repair,” or arguing for the continuation of the industrial agriculture system. Our empirical case relates to water pollution from nitrogen fertilizer and draws data from a sample of over 150 interviews with row-crop farmers in the midwestern United States. We find that farmers defend this system by denying agriculture’s causal role and proposing the potential for within-system solutions. They perform these defenses by drawing on ideological positions (agrarianism, market-fundamentalism and techno-optimism) and may be ultimately led to seek system maintenance because they are unable to envision an alternative to the industrial agriculture system.
In this work, we investigated the possible genotoxic and cytotoxic effects of the antibacterial agent Triclosan in hemocytes of the freshwater bivalve Zebra mussel (
Dreissena polymorpha). For this ...study, we used several biomarkers for
in vivo experiments (96
h of exposure) carried out at three possible environmental Triclosan concentrations (1, 2, 3
nM). We used the single cell gel electrophoresis (SCGE) assay, the micronucleus test (MN test) and the measure of the apoptotic frequency (Halo assay) to measure the genotoxic potential of Triclosan, and the neutral red retention assay (NRRA) as a measure of lysosomal membrane stability to identify general cellular stress. We observed significant increases in all of the genotoxic biomarkers examined as early as 24
h after initial exposure, as well as a clear destabilization of lysosomal membranes (after 48
h), indicating that this chemical is potentially dangerous for the entire aquatic biocoenosis. A comparison of these
in vivo data with existing data from
in vitro experiments allowed us to suggest possible mechanisms of action for Triclosan in this bivalve. Although further studies are needed to confirm the possible modes of action, our study is the first to report on the effects of this widespread antibiotic on freshwater invertebrates.
The U.S. federal government, as well as many state and local governments, operate a number of conservation programs aimed at ameliorating the environmental problems associated with agriculture. While ...motives and barriers to conservation program participation and adoption of conservation practices have been extensively studied, the direct impacts of programs on ongoing farm operations remains underexplored. To examine the effects of conservation programs on nitrogen management, an aspect of crop production with significant environmental impacts we conducted interviews with 154 corn producers in three Midwestern U.S. states with a range of program experiences. We found that programs shifted farmer N management behavior through three social processes: (1) engaging farmers in the conservation system by introducing them to the state and federal conservation agencies, (2) incentivizing trialing of specific N management practices, and (3) increasing practice adoption through continued program engagement. Working-lands programs were far more effective at shifting on-farm nutrient management practices than land retirement, certification, or outreach-based programs, though all programs had the indirect benefit of increasing farmer familiarity with conservation agencies and programs. Working-lands programs directly motivated practice adoption; including soil testing regimes, implementing nutrient management plans, and splitting nitrogen applications to improving availability; by reducing producer risk and providing technical assistance, especially whole-farm planning. The additional benefits of all programs were moderated by participant selection bias, in particular that program participants were more predisposed to conservation efforts by existing stewardship and innovation attitudes.
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•The storage facilities for animal manure determine ammonia and odour emissions.•These emissions cause environmental problems and annoyance to inhabitants.•The determination of ...emission rates is useful to quantify these problems.•Ammonia and odours have been detected studying four storage facilities during two years.•Both ammonia and odour emitted depended upon slurries’ characteristics and environmental parameters.
Ammonia and odour emissions from one lagoon (Lagoon 1: pig slurry) and three tanks (Tank 2: cow slurry; Tank 3: digestate from pig slurry and energy crops; Tank 4: digestate from pig and cow slurries plus energy crop) used for slurry storage were sampled for two years (2015–2017) in livestock farms that differed for animal breeding and manure management (anaerobic digestion).
On average, the ammonia emission rate (AER) was higher for Tank 3 (AER of 30.68 ± 28.1 g N-NH3 m−2 d−1) than for Lagoon 1 and Tank 2 and 4, i.e. 9.29 ± 14.89 gN-NH3 m−2 d−1, 9.38 ± 13.75 g N-NH3 m−2 d−1, 15.74 ± 21.91 g N-NH3 m−2 d−1, respectively. PLS regression analysis (R2 = 0.544; R2Adj. = 0.484) indicated that temperature was the main predictor of ammonia emitted, followed by concentration in the slurry of total ammonia and the relative percentage of volatile solids (VS).
On the other hand, PLS analysis (R2 = 0.529, R2adj. = 0.417) indicated that odour emissions from animal slurry storages depended similarly upon total solids and VS (both referred to fresh weight) slurry contents, TAN/TKN ratio and degrees of biological stability (measured by anaerobic biogas potential – ABP), resulting in the Specific Odours Emission Rates (SOER) of 12,124 ± 7,914 and 35,207 ± 41,706 OUE m−2 h−1, 65,430 ± 45,360 and 43,971 ± 53,350 OUE m−2 h−1, for Lagoon 1 and Tanks 2, 3 and 4. These results suggest covering the tanks to limit both ammonia and odour emissions.
This work aimed to measure the odour impact of untreated cow and pig slurries and treated (digestate and liquid fraction of digestate) manures when they were used on soil at a field scale, while also ...testing different spreading methods, i.e. surface vs. injection. Five experiments were performed in 2012–2016 on different farms. Odours were quantitatively (specific odour emission rate – SOER) (OUEm−2h−1) measured by using dynamic olfactometry and qualitatively, i.e. to obtain an “odour fingerprint”, by using an electronic nose (EN).
Anaerobic digestion was effective in allowing the reduction of potential odour emission from digestates, so that when they were dosed on soil, odours emitted were much lower than those from soils on which untreated slurries were used. Slurries/digestate injection reduced much more odour emitted by soils so that SOER tended to become more similar to that of the control (untreated soil) although the odours were slightly greater.
Odour fingerprint data indicated that there was a direct correlation between SOER and odour fingerprints. This was due to the ability of EN to detect ammonia, S-compounds and methane that were (the first two mainly), also, responsible for odours. Very good regression was found for Log SOER and EN by using a Partial Least Square (PLS) approach (R2=0.73; R2cv=0.66; P<0.01) for matrices used to fertilize soils in lab tests. Unfortunately, regression was not so good when odour data from field experiments on soil were used, so that EN cannot be proposed to replace olfactometry. EN fingerprints for control (Blank) and injected organic matrices were virtually identical, due to the creation of cavities in the soil during the injection that decreased the treated surface. Anaerobic digestion and subsequent digestate injection allowed us to reduce odour impact, avoiding annoyance to local inhabitants.
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•Anaerobic digestion reduces odours impact because of degradation of organic matter.•Anaerobic digestion (AD) coupled with manure injection reduced odour emissions.•Specific Odour Emission Rate (SOER) well correlated with electronic nose fingerprint•Electronic nose can replace SOER in measuring odour impact.
Excess nitrogen (N) loading in the Mississippi River basin is a major water quality issue, encompassing large spatial scales and feedbacks between social and biophysical entities. Effective ...management depends on reductions in agricultural N loading, mainly from the Corn Belt region in the upper reaches of the basin. In this study, we evaluated the role of federal Nutrient Task Force policy on N management from 2000 to 2015. We analyzed trends in nitrate (NO3−) concentrations from monitoring data in 148 priority watersheds. We compared water quality trends with state nutrient reduction strategies, monitoring efforts, and land use. Of the 148 watersheds, 13 displayed a significant decrease in NO3− concentrations, 24 displayed a significant increase, 51 displayed a nonsignificant trend, and 60 had insufficient data to analyze. We demonstrate that policy efforts on a large scale are slow to establish, but states and watersheds that showed signs of policy acting successfully could serve as examples for improved N management moving forward. Despite considerable variability, states with the most comprehensive strategies, evidenced by word count and presence of recommended elements, were almost exclusively located in the Corn Belt region. States with more thorough nutrient reduction strategies also tended to have a larger number of monitoring sites in priority watersheds (R = .42), demonstrating the potential for adaptive management. States with the most consistent improvements in NO3− concentrations tended to have the most comprehensive policies, whereas variation in water quality trends was partly attributed to land use factors including slope and dominance of corn (Zea mays L.) and soy Glycine max (L.) Merr..
► Cocaine as new environmental pollutant. ► Cyto-genotoxic effects measured by a biomarker battery. ► Cocaine is able to induce significant cellular and genetic damage. ► Cocaine is a potential ...danger for aquatic non-target organisms.
The increase in global consumption of illicit drugs has produced not only social and medical problems but also a potential new environmental danger. Indeed, it has been established that drugs consumed by humans end up in surface waters, after being carried through the sewage system. Although many studies to measure concentrations of several drugs of abuse in freshwater worldwide have been conducted, no data have been available to evaluate their potentially harmful effects on non-target organisms until now. The present study represents the first attempt to investigate the cyto-genotoxic effects of cocaine, one of the primary drugs consumed in Western Countries, in the biological model Dreissena polymorpha by the use of a biomarker battery. We performed the following tests on Zebra mussel hemocytes: the single cell gel electrophoresis (SCGE) assay, the apoptosis frequency evaluation and the micronucleus assay (MN test) for the evaluation of genotoxicity and the lysosomal membranes stability test (neutral red retention assay; NRRA) to identify the cocaine cytotoxicity. We exposed the molluscs for 96h to three different nominal concentrations in water (40ngL−1; 220ngL−1; and 10μgL−1).
Cocaine caused significant (p<0.05) primary DNA damage in this short-term experiment, but it also caused a clear increase in micronucleated cells and a marked rise in apoptosis, which was evident in samples from even the lowest environmental cocaine concentration. Because cocaine decreased the stability of lysosomal membranes, we also highlighted its cytotoxicity and the possible implications of oxidative stress for the observed genotoxic effects.
Understanding what drives farmers' voluntary adoption of nutrient and soil best management practices has important consequences for many environmental outcomes including water quality. We build on ...research revealing the need for simultaneous use of multiple nitrogen best management practices to achieve water quality improvement goals. Using social, economic and attitudinal variables we predict the use of multiple nitrogen best management practices at three time points: current use (2013), past use (before 2013), and likelihood of use on their largest field in the next three years. Our empirical analysis uses structural equation modeling with latent variables and 2014 farmer survey data from three Midwestern US states. Most farmers in our sample used at least one of the six best management practices. Our results reveal that farmers' attitudes, use of information sources, and conservation program participation affect the number of nitrogen best management practices concurrently in use at multiple time points.
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