Recycling Of Organic Matter Research Articles

Impact of Habitat on the Development of Coprophagous and Xylophagous Coleopteran Insects in the Park of Bamimgui-Bangoran (Central African Republic)

Coprophagous and Xylophagous Coleopterans are equally impacted by the fragmentation of ecosystems and are recognized for their character as indicators of certain ecosystem functions, such as the recycling of organic matter and pollination. Thus, as part of the program to restore degraded ecosystems in protected areas and others sectors of the Bamingui-Bangoran Prefecture in the Central African Republic (CAR), an inventory of insect species according to their ecological profile is needed. Insects were collected over 8 hectares corresponding to 6 different habitats in the Bamingui-Bangoran park. Sixty different traps were installed in each habitat with 100 meters of distance between the traps. The measured parameters are the number of individuals collected per week. As results, 8 coleopteran families (4 Coprophagous families and 4 Xylophagous families) were identified. The Coprophagous and Xylophagous Coleopterans were much abounded in grassy savannahs with much mixing trees with Imperata cylindrica and in grassy and shrubby savannas with many flowering plants (Melliferous) and less abounded in grassy and shrubby savannahs domined by Imperata cylindrica. However, repartitions of individuals fit uniform distribution in all coleopteran families belonging to Xylophagous group whereas in Coprophagous, uniform distribution fit was established only for one family.

Fungal communities in soils under global change.

Soil fungi play indispensable roles in all ecosystems including the recycling of organic matter and interactions with plants, both as symbionts and pathogens. Past observations and experimental manipulations indicate that projected global change effects, including the increase of CO2 concentration, temperature, change of precipitation and nitrogen (N) deposition, affect fungal species and communities in soils. Although the observed effects depend on the size and duration of change and reflect local conditions, increased N deposition seems to have the most profound effect on fungal communities. The plant-mutualistic fungal guilds - ectomycorrhizal fungi and arbuscular mycorrhizal fungi - appear to be especially responsive to global change factors with N deposition and warming seemingly having the strongest adverse effects. While global change effects on fungal biodiversity seem to be limited, multiple studies demonstrate increases in abundance and dispersal of plant pathogenic fungi. Additionally, ecosystems weakened by global change-induced phenomena, such as drought, are more vulnerable to pathogen outbreaks. The shift from mutualistic fungi to plant pathogens is likely the largest potential threat for the future functioning of natural and managed ecosystems. However, our ability to predict global change effects on fungi is still insufficient and requires further experimental work and long-term observations. Citation: Baldrian P, Bell-Dereske L, Lepinay C, Větrovský T, Kohout P (2022). Fungal communities in soils under global change. Studies in Mycology 103: 1-24. doi: 10.3114/sim.2022.103.01.

Biomass partitioning and nutrient fluxes in Silphium perfoliatum and silage maize cropping systems

Cup plant cultivation as feedstock for anaerobic digestion has become an emerging topic in European Agriculture. Although there is a gap in methane yields between cup plant and the benchmark crop silage maize, cup plant as a perennial crop provides several ecological advantages. Amongst others, studies have proven its potential for carbon sequestration. With the present study, we addressed the gap in knowledge about biomass partitioning above- and belowground as well as recycling of organic matter and nutrients for cup plant and compared the results to silage maize. Therefore, a 2 year field experiment was conducted under practical conditions on rather shallow soil conditions in a low mountain landscape in Western Germany. Relevant plant fractions like litterfall, yield biomass and stubbles were collected continuously and analyzed for their nutrient contents. Results show that the cup plant is characterized by more than 2000 kg ha− 1 a− 1 of pre-harvest losses with a high palatability. In sum, only 77% of the grown cup plant biomass can be harvested in contrast to 96% of silage maize. Thus, an intense, element-specific nutrient recycling takes place in cup plant whereas this is negligible in silage maize. Furthermore, clearly different, element-specific nutrient exports with yield were highlighted. In cup plant, exports were distinctly lower for nitrogen but several times higher for calcium compared to silage maize. Cup plant also showed 36% more roots with higher root masses particularly in the subsoil.Graphical abstract

How long does a brachiopod shell last on a seafloor? Modern mid‐bathyal environments as taphonomic analogues of continental shelves prior to the Mesozoic Marine Revolution

AbstractCarbonate skeletal remains are altered and disintegrate at yearly to decadal scales in present‐day shallow‐marine environments with intense bioerosion and dissolution. Present‐day brachiopod death assemblages are invariably characterized by poor preservation on continental shelves, and abundant articulated shells of brachiopods with complete brachidia are thus not expected to be preserved if not rapidly buried. However, such preservation is paradoxically observed in shallow‐water Palaeozoic and Mesozoic brachiopod assemblages. Here, we show that a bathyal death assemblage time‐averaged to several millennia (Adriatic Sea) consists of sediment‐filled articulated shells of Gryphus vitreus with complete brachidia. Post‐mortem age distributions indicate that disintegration half‐lives exceed several centuries (c. 500–1700 years). The high frequency of articulated but centuries‐old shells (>50%) and the fitting of taphonomic models to post‐mortem ages indicate that disarticulation half‐life is unusually long (c. 200 years). Rapid sediment filling of shells: (1) inhibited disarticulation, loop fragmentation and colonization by coelobites; and (2) induced precipitation of ferromanganese oxides at redox fronts within shells. Sediment‐filled articulated shells, however, still resided at the sediment–water interface as indicated by encrusters and sponges that infested them after death. Sediment‐filled shells disintegrated through bioerosion and physical wear when residence in the taphonomically active zone exceeded c. 2000 years. We suggest that the articulation paradox is driven by the Mesozoic Marine Revolution (MMR) that escalated predation, bioturbation and organic matter recycling, all intensifying shell disintegration. A scenario with slow disarticulation in bathyal environments may have lead to preservation of articulated shells in shallow‐water assemblages prior to the MMR.

Systematics and evolution of predatory flower flies (Diptera: Syrphidae) based on exon‐capture sequencing

AbstractFlower flies (Diptera: Syrphidae) are one of the most species‐rich dipteran families and provide important ecosystem services such as pollination, biological control of pests, recycling of organic matter and redistributions of essential nutrients. Flower fly adults generally feed on pollen and nectar, but their larval feeding habits are strikingly diverse. In the present study, high‐throughput sequencing was used to capture and enrich phylogenetically and evolutionary informative exonic regions. With the help of thebaitfishersoftware, we developed a new bait kit (SYRPHIDAE1.0) to target 1945 CDS regions belonging to 1312 orthologous genes. This new bait kit was successfully used to exon capture the targeted loci in 121 flower fly species across the different subfamilies of Syrphidae. We analysed different amino acid and nucleotide data sets (1302 loci and 154 loci) with maximum likelihood and multispecies coalescent models. Our analyses yielded highly supported similar topologies, although the degree of the SRH (global stationarity, reversibility and homogeneity) conditions varied greatly between amino acid and nucleotide data sets. The sisterhood of subfamilies Pipizinae and Syrphinae is supported in all our analyses, confirming a common origin of taxa feeding on soft‐bodied arthropods. Based on our results, we define Syrphinistat.rev.to include the generaToxomerusandParagus. Our divergence estimate analyses withbeastinferred the origin of the Syrphidae in the Lower Cretaceous (125.5–98.5 Ma) and the diversification of predatory flower flies around the K–Pg boundary (70.61–54.4 Ma), coinciding with the rise and diversification of their prey.

Morphology and multigene phylogeny reveal a new order and a new species of wood-inhabiting basidiomycete fungi (Agaricomycetes).

Dead wood-associated fungi play an important role in wood degradation and the recycling of organic matter in the forest ecological system. Xenasmataceae is a cosmopolitan group of wood-rotting fungi that grows on tropical, subtropical, temperate, and boreal vegetation. In this study, a new fungal order, Xenasmatales, is introduced based on both morphology and multigene phylogeny to accommodate Xenasmataceae. According to the internal transcribed spacer and nuclear large subunit (ITS+nLSU) and nLSU-only analyses of 13 orders, Xenasmatales formed a single lineage and then grouped with orders Atheliales, Boletales, and Hymenochaetales. The ITS dataset revealed that the new taxon Xenasmatella nigroidea clustered into Xenasmatella and was closely grouped with Xenasmatella vaga. In the present study, Xenasmatella nigroidea collected from Southern China is proposed as a new taxon, based on a combination of morphology and phylogeny. Additionally, a key to the Xenasmatella worldwide is provided.

Novel Freshwater Ascomycetes from Spain.

Freshwater ascomycetes are a group of fungi of great ecological importance because they are involved in decomposition processes and the recycling of organic matter in aquatic ecosystems. The taxonomy of these fungi is complex, with representatives in several orders of the phylum Ascomycota. In the present study, we collected ninety-two samples of plant debris submerged in freshwater in different locations in Spain. The plant specimens were placed in wet chambers and developed several fungi that were later isolated in pure culture. A main phylogenetic tree using the nucleotide sequences of D1–D2 domains of the 28S nrRNA gene (LSU) was built to show the taxonomic placement of all our fungal strains, and, later, individual phylogenies for the different families were built using single or concatenated nucleotide sequences of the most suitable molecular markers. As a result, we found a new species of Amniculicola that produces a coelomycetous asexual state, a new species of Elongatopedicellata that produces an asexual state, a new species of Neovaginatispora that forms both sexual and asexual states in vitro, and the sexual states of two species of Pyrenochaetopsis, none of which have been reported before for these genera. In addition, we describe a new species of Pilidium characterized by the production of copper-colored globose conidiomata, and of Pseudosigmoidea, which produces well-developed conidiophores.

Bacterial, Phytoplankton, and Viral Distributions and Their Biogeochemical Contexts in Meromictic Lake Cadagno Offer Insights into the Proterozoic Ocean Microbial Loop

ABSTRACTLake Cadagno, a permanently stratified high-alpine lake with a persistent microbial bloom in its chemocline, has long been considered a model for the low-oxygen, high-sulfide Proterozoic ocean. Although the lake has been studied for over 25 years, the absence of concerted study of the bacteria, phytoplankton, and viruses, together with primary and secondary production, has hindered a comprehensive understanding of its microbial food web. Here, the identities, abundances, and productivity of microbes were evaluated in the context of Lake Cadagno biogeochemistry. Photosynthetic pigments together with 16S rRNA gene phylogenies suggest the prominence of eukaryotic phytoplankton chloroplasts, primarily chlorophytes. Chloroplasts closely related to those of high-alpine-adapted Ankyra judayi persisted with oxygen in the mixolimnion, where photosynthetic efficiency was high, while chloroplasts of Closteriopsis-related chlorophytes peaked in the chemocline and monimolimnion. The anoxygenic phototrophic sulfur bacterium Chromatium dominated the chemocline along with Lentimicrobium, a genus of known fermenters. Secondary production peaked in the chemocline, which suggested that anoxygenic primary producers depended on heterotrophic nutrient remineralization. The virus-to-microbe ratio peaked with phytoplankton abundances in the mixolimnion and were at a minimum where Chromatium abundance was highest, trends that suggest that viruses may play a role in the modulation of primary production. Through the combined analysis of bacterial, eukaryotic, viral, and biogeochemical spatial dynamics, we provide a comprehensive synthesis of the Lake Cadagno microbial loop. This study offers a new ecological perspective on how biological and geochemical connections may have occurred in the chemocline of the Proterozoic ocean, where eukaryotic microbial life is thought to have evolved.

Paleoenvironmental evolution during the Early Eocene Climate Optimum in the Chicxulub impact crater

The Early Eocene represents the warmest climate during the Cenozoic Era punctuated by transient warming events. Here, we apply for the first time biomarker and stable isotope data to describe the depositional and environmental changes at the actual Chicxulub impact crater [International Ocean Discovery Program (IODP) Site M0077A] during the Early Eocene (∼56–48 Ma) including the Early Eocene Climate Optimum (EECO; ∼53–49 Ma). TEX86-based reconstructions indicate elevated sea surface temperature around 37°C for the entire succession, punctuated by warmer and cooler periods (37.8°C, 35.7°C, respectively). Biomarker and δ13C-org data of the core sediments reveal a shift from an organic-lean lower to an organic-rich upper section of the Early Eocene interval. Embedded in the lower section is a prominent organic-rich black shale layer. The lower section, directly overlying strata deposited upon the Paleocene-Eocene Thermal Maximum (PETM), is organically lean with low biomarker concentrations indicating low primary productivity. In the upper section, higher concentrations of algal and bacterial biomarkers are ascribed to high primary productivity and nitrogen fixation in an epipelagic zone, potentially supported by upwelling. The organic-rich black shale layer exhibits a negative δ13C-org isotope excursion ascribed to recycling of 13C-depleted organic matter via upwelling attributed to a transient hyperthermal event.

Dynamic change in an ocean desert: Microbial diversity and trophic transfer along the 110 °E meridional in the Indian Ocean

The eastern Indian Ocean is among the most oligotrophic regions in the world and has been described as an ocean desert. Limited information exists on microbial community profiles from marker gene data, and an open question in this system is how energy is transported from the base of the food web to higher trophic levels. Here we show that, along a 3300 km long transect in the ultra-oligotrophic eastern Indian Ocean, both alpha and beta diversity metrics for prokaryotic and eukaryotic trophic groups revealed remarkably strong latitudinal trends. The latitudinal Shannon diversity pattern for autotrophic eukaryotes furthermore aligned with the isotopic δ13C ratios of particulate organic carbon, fractionated zooplankton and hand-picked fish larvae, suggesting a close trophic linkage between autotrophic eukaryotes and higher trophic levels. Our data also showed an increasing contribution of eukaryotic mixotrophs and a high contribution of heterotrophic eukaryotes towards warmer waters. These findings highlight that not only the recycling of organic matter via bacterial regeneration is important in this system but that mixo- and heterotrophic eukaryotes play a major role in redistributing energy within the marine food web of these oligotrophic waters. Our data provide a baseline to understand how environmental changes such as warming surface waters might impact the open-ocean food web in this oligotrophic basin.

Food web structure and intraguild predation affect ecosystem functioning in an established plankton model

AbstractUnderstanding how marine microbial food webs and their ecosystem functions are changing is crucial for projections of the future ocean. Often, simplified food web models are employed and their solutions are only evaluated against available observations of plankton biomass. With such an approach, it remains unclear how different underlying trophic interactions affect interpretations of plankton dynamics and functioning. Here, we quantitatively compare four hypothetical food webs to data from an existing mesocosm experiment using a refined version of the Minimum Microbial Food Web model. Food web representations range from separated food chains to complex food webs featuring additional trophic links including intraguild predation (IGP). Optimization against observations and taking into account model complexity ensures a fair comparison of the different food webs. Although the different optimized model food webs capture the observations similarly well, projected ecosystem functions differ depending on the underlying food web structure and the presence or absence of IGP. Mesh‐like food webs dominated by the microbial loop yield higher recycling and net primary production (NPP) than models dominated by the classical diatom‐copepod food chain. A high degree of microzooplankton IGP increases NPP and organic matter recycling, but decreases trophic transfer efficiency (TTE) to copepods. Copepod production, the trophic role of copepods, and TTE are more sensitive to initial biomass changes in chain‐like than in complex food webs. Measurements resolving trophic interactions, in particular those quantifying IGP, remain essential to reduce model uncertainty and allow sound conclusions for ecosystem functioning in plankton ecosystems.

Distribution of physical and chemical variables in the water column and characterization of the bottom sediment in a macrotidal estuary on the Amazon coast of the state of Maranhão, Brazil

The objective of this research was to characterize the distribution of dissolved nutrients at six sampling stations in the estuary of the Anil River (ARE) and characterize the bottom sediment. The study area is influenced by a tropical climate and semidiurnal macrotidal regime. Sampling of the surface water and sediment was performed in the main channel at six sampling stations distributed along the estuary in the rainy period (May 9th) and dry period (October 5th) during the spring. Physical variables were collected with the aid of a HANNA HI-8424 multi-parameter probe (water temperature, salinity, pH, dissolved oxygen, and turbidity) and YSI CTD (conductivity, temperature, and depth) probe. A van Veen dredge was used for the collection of bottom sediment from the main channel. The sedimentological results were heterogeneous. Grain size ranged from very fine to medium sand. Dissolved nutrients in the ARE had different sources depending on the season. Continental and fluvial inputs, evidenced by salinity values, governed the distribution of nutrients in the rainy period (January to June), whereas nutrient concentrations were related to the recycling of organic material in the estuary in the dry season (July to December). The considerable presence of sand in the main channel indicates that the sediments available in ARE are exposed to intense hydrodynamics. The distribution of nutrients and the grain size revealed the occurrence of different sources in the estuary according to the rainfall regime and the intense hydrodynamics of tidal currents (semidiurnal macrotidal).
 Keywords: dissolved nutrients, estuarine environment, sedimentology.

The Biodegradation of Soil Organic Matter in Soil-Dwelling Humivorous Fauna.

Soil organic matter contains more carbon than global vegetation and the atmosphere combined. Gaining access to this source of organic carbon is challenging and requires at least partial removal of polyphenolic and/or soil mineral protections, followed by subsequent enzymatic or chemical cleavage of diverse plant polysaccharides. Soil-feeding animals make significant contributions to the recycling of terrestrial organic matter. Some humivorous earthworms, beetles, and termites, among others, have evolved the ability to mineralize recalcitrant soil organic matter, thereby leading to their tremendous ecological success in the (sub)tropical areas. This ability largely relies on their symbiotic associations with a diverse community of gut microbes. Recent integrative omics studies, including genomics, metagenomics, and proteomics, provide deeper insights into the functions of gut symbionts. In reviewing this literature, we emphasized that understanding how these soil-feeding fauna catabolize soil organic substrates not only reveals the key microbes in the intestinal processes but also uncovers the potential novel enzymes with considerable biotechnological interests.

Soil Fertility Properties, Leaf Nutrient Status and Yield Of Coconut and Intercrops as Influenced and Coconut Based Cropping System in Coastal Plain of Western India

An experiment was conducted during 2013 -2019 to study the impact of intergrated nutrient management through organic matter recycling (OMR) on the soil properties, leaf nutrient status and yield of coconut and its components crops at Regional Coconut Research Station (AICRP on Palms), Bhatye, Maharashtra, India. The experiment was laid out in 0.40 ha with four treatments namely T1, T2, T3 and T4. Results showed that, INM practices significantly improved the soil physico-chemical, biological properties and leaf nutrient status, whereas it was more prominent for the T1 treatment. The soil organic carbon content during post experimental period gradually increased in the organic recyclable treatment under cropping system (0.80 to 0.86%) compared to monocropping (0.60%). The recyclable biomass produced from the system varied between 9.0 - 18.0 t/ha/year and vermicompost produced was 4.8 to 10.2 t/ha/year by composting through earthworm. The nut yield (147.2 and 138.4 nuts/palm), copra output (25.75 and 23.06 kg/palm) and oil output (17.11 and 15.72 kg/palm) under treatment T1 and T2 were on par and differed significantly compared to monocrop. Bangladesh J. Bot. 50(4): 1067-1075, 2021 (December)

Enzymatic Bioprospecting of Fungi Isolated from a Tropical Rainforest in Mexico.

The humid tropical environment provides an ideal place for developing a high diversity of plants; this is why it is an interesting site for the enzymatic bioprospecting of fungi that are responsible for the recycling of organic matter in an efficient and accelerated way and whose enzymes could have multiple biotechnological applications. For this study, 1250 isolates of macroscopic and microscopic fungal morphotypes were collected from soil, leaf litter, and wood. One hundred and fifty strains (50 from each source) were selected for the enzymatic screening. From the first phase, 51 strains with positive activity for laccase, protease, amylase, xylanase, and lipase enzymes were evaluated, of which 20 were isolated from leaf litter, 18 from the soil, and 13 from wood. The 10 best strains were selected for the enzymatic quantification, considering the potency index and the production of at least two enzymes. High laccase activity was detected for Trametes villosa FE35 and Marasmius sp. CE25 (1179 and 710.66 U/mg, respectively), while Daedalea flavida PE47 showed laccase (521.85 U/mg) and protease activities (80.66 U/mg). Fusarium spp. PH79 and FS400 strains had amylase (14.0 U/mg, 49.23 U/mg) and xylanase activities (40.05 U/mg, 36.03 U/mg) respectively. These results confirm the enzymatic potential of fungi that inhabit little-explored tropical rainforests with applications in industry.

A Historical Collection of Termites in Ferrara: Recovery, Cataloguing and Geographical Analyses.

Simple SummaryTermites, an insect group relevant for recycling of organic matter, are also biodeteriogenic organisms that cause serious damages to wooden structures in anthropogenic environments. Professor Antonio Springhetti, a renowned Italian entomologist who studied termites in Italy from 1950 to around 1990, collected many specimens during his field campaigns, and his collection was enriched by termite samples from around the world donated by other entomologists. His precious collection, preserved at the University of Ferrara, represents not only a valuable scientific tool for studies on ecologically relevant insects that may seriously damage historical buildings and ancient libraries but also an important cultural asset.Termites are an insect group relevant for recycling of organic matter, but they are also biodeteriogenic and may cause serious damages to wooden structures (including historical buildings and ancient libraries) in anthropogenic environments. The collection of Italian and foreign termites gathered over the years by Antonio Springhetti, Professor of Zoology at the University of Ferrara (Ferrara, Italy) and internationally renowned entomologist, contains over 44,000 specimens, collected by Springhetti during his field campaigns or donated by other entomologists from all over the world. The collection is currently preserved at the Department of Life Sciences and Biotechnology of the University of Ferrara. Unfortunately, all documents, publications and notes concerning the Springhetti Collection were lost; thus, in 2020, the collection was completely re-catalogued within the University Museum System and analyzed in detail. The collection contains specimens dating back to 1878 and represents not only a valuable scientific tool for studies on these ecologically relevant insects that may cause damages to historical buildings, ancient books and artworks but also an important cultural asset for the University Museum System.

Effect of powder and extract of Ritchiea reflexa (Thonn.) Gilg et Benedict and Ctenium elegans Kunth on Amitermes evuncifer Blattodea, Termitinae

Termites play key roles in the ecosystems functioning, especially in the recycling of organic matter. However, few are considered pests because they cause damages to crops and wooden structures. Long based on the use of synthetic pesticides, the control of pestiferous termites is now focused on environmental friendly means including the use of plant extracts. Here, powder, acetonic and ethanolic extracts of Ctenium elegans and Ritchiea reflexa were tested against Amitermes evuncifer. The phytochemical study on extracts exhibited tannins and terpenoids in both species, and steroids only in the ethanolic extract of R. reflexa. Five concentrations of each formulation were used against two controls (negative and positive). Six replicates were made for each concentration using 25 (for extracts) and 30 (for powder) healthy termite workers in petri dishes. All concentrations reduced the survival duration and life expectancy of termites. In 1.83±0.41 days, the higher concentration (6 mg/cm2) of R. reflexa ethanolic extract killed all termites against 6.67±1.63, and 8.67±0.52 days for the same concentration of acetonic extract and powder, respectively. On the other hand, it took 11.17±2.64; 5.5±0.55, and 5.33±0.52 days, for powder, ethanolic and acetone extracts of C. elegans to kill all the tested termites, respectively. The results suggested the use of these formulations as a botanical insecticide in termite management. Key words: Amitermes evuncifer, biopesticides, Ctenium elegans, environment protection, Ritchiea reflexa.

Distribution of methionine sulfoxide reductases in fungi and conservation of the free-methionine-R-sulfoxide reductase in multicellular eukaryotes

Methionine, either as a free amino acid or included in proteins, can be oxidized into methionine sulfoxide (MetO), which exists as R and S diastereomers. Almost all characterized organisms possess thiol-oxidoreductases named methionine sulfoxide reductase (Msr) enzymes to reduce MetO back to Met. MsrA and MsrB reduce the S and R diastereomers of MetO, respectively, with strict stereospecificity and are found in almost all organisms. Another type of thiol-oxidoreductase, the free-methionine-R-sulfoxide reductase (fRMsr), identified so far in prokaryotes and a few unicellular eukaryotes, reduces the R MetO diastereomer of the free amino acid. Moreover, some bacteria possess molybdenum-containing enzymes that reduce MetO, either in the free or protein-bound forms. All these Msrs play important roles in the protection of organisms against oxidative stress. Fungi are heterotrophic eukaryotes that colonize all niches on Earth and play fundamental functions, in organic matter recycling, as symbionts, or as pathogens of numerous organisms. However, our knowledge on fungal Msrs is still limited. Here, we performed a survey of msr genes in almost 700 genomes across the fungal kingdom. We show that most fungi possess one gene coding for each type of methionine sulfoxide reductase: MsrA, MsrB, and fRMsr. However, several fungi living in anaerobic environments or as obligate intracellular parasites were devoid of msr genes. Sequence inspection and phylogenetic analyses allowed us to identify non-canonical sequences with potentially novel enzymatic properties. Finaly, we identified several ocurences of msr horizontal gene transfer from bacteria to fungi.

Measuring ammonia and odours emissions during full field digestate use in agriculture

The use of digestate in agriculture represents an opportunity for reducing the use of synthetic fertilizers while promoting nutrient and organic matter recycling, i.e. contributing to a circular economy. However, some environmental impacts could result from digestate use, with particular reference to N emissions, which can contribute to particulate matter formation in the atmosphere. So, correct digestate spreading methods need to be tested to reduce ammonia emission and, possibly, also to avoid annoyance to the inhabitants. In this work a digestate from organic wastes was used as a fertilizer by its injection at 15 cm, in comparison with a synthetic one (urea) for three consecutive years in open fields, measuring ammonia and odours emission. On average, the ammonia emission from digestate was of 25.6 ± 9.4 kg N Ha−1 (11.6% ± 4 of Total Ammonia Nitrogen - TAN - dosed), while urea emitted 24.8 ± 8.3 kg N Ha−1 (13.4% ± 4.5 of TAN dosed). The injected digestate also emitted less odour than urea (601 ± 531 and 1767 ± 2221 OU m−2 h−1, respectively), being ammonia coming from urea hydrolysis responsible for odour productions.The different N fertilizers did not lead to differences in crop yields, i.e. 18.5 ± 2.9 Mg grain Ha−1 and 17.4 ± 1.2 Mg grain Ha−1 for digestate and urea respectively.

Early Diagenesis in the Hypoxic and Acidified Zone of the Northern Gulf of Mexico: Is Organic Matter Recycling in Sediments Disconnected From the Water Column?

Hypoxia and associated acidification are growing concerns for ecosystems and biogeochemical cycles in the coastal zone. The northern Gulf of Mexico (nGoM) has experienced large seasonal hypoxia for decades linked to the eutrophication of the continental shelf fueled by the Mississippi River nutrient discharge. Sediments play a key role in maintaining hypoxic and acidified bottom waters, but this role is still not completely understood. In the summer 2017, when the surface area of the hypoxic zone in the nGoM was the largest ever recorded, we investigated four stations on the continental shelf differentially influenced by river inputs of the Mississippi-Atchafalaya River System and seasonal hypoxia. We investigated diagenetic processes under normoxic, hypoxic, and nearly anoxic bottom waters by coupling amperometric, potentiometric, and voltammetric microprofiling with high-resolution diffusive equilibrium in thin-films (DET) profiles and porewater analyses. In addition, we used a time-series of bottom-water dissolved oxygen from May to November 2017, which indicated intense O2 consumption in bottom waters related to organic carbon recycling. At the sediment-water interface (SWI), we found that oxygen consumption linked to organic matter recycling was large with diffusive oxygen uptake (DOU) of 8 and 14 mmol m–2 d–1, except when the oxygen concentration was near anoxia (5 mmol m–2 d–1). Except at the station located near the Mississippi river outlet, the downcore pore water sulfate concentration decrease was limited, with little increase in alkalinity, dissolved inorganic carbon (DIC), ammonium, and phosphate suggesting that low oxygen conditions did not promote anoxic diagenesis as anticipated. We attributed the low anoxic diagenesis intensity to a limitation in organic substrate supply, possibly linked to the reduction of bioturbation during the hypoxic spring and summer.