Availability Of Organic Matter Research Articles

Nutrient release and flux dynamics of CO2, CH4, and N2O in a coastal peatland driven by actively induced rewetting with brackish water from the Baltic Sea

Abstract. The rewetting of drained peatlands supports long-term nutrient removal in addition to reducing emissions of carbon dioxide (CO2) and nitrous oxide (N2O). However, rewetting may lead to short-term nutrient leaching into adjacent water and high methane (CH4) emissions. The consequences of rewetting with brackish water on nutrient and greenhouse gas (GHG) fluxes remain unclear, although beneficial effects such as lower CH4 emissions seem likely. Therefore, we studied the actively induced rewetting of a coastal peatland with brackish water, by comparing pre- and post-rewetting data from the peatland and the adjacent bay. Both the potential transport of nutrients into adjacent coastal water and the shift in GHG fluxes (CO2, CH4, and N2O) accompanying the change from drained to inundated conditions were analyzed based on measurements of the surface water concentrations of nutrients (dissolved inorganic nitrogen, DIN, and phosphate, PO43-), oxygen (O2), components of the CO2 system, CH4, and N2O together with manual closed-chamber measurements of GHG fluxes. Our results revealed higher nutrient concentrations in the rewetted peatland than in the adjacent bay, indicating that nutrients leached out of the peat and were exported to the bay. A comparison of DIN concentrations of the bay with those of an unaffected reference station showed a significant increase after rewetting. The maximum estimated nutrient export (mean ± 95 % confidence level) out of the peatland was calculated to be 33.8 ± 9.6 t yr−1 for DIN-N and 0.24 ± 0.29 t yr−1 for PO4-P, depending on the endmember (bay vs. reference station). The peatland was also a source of GHG in the first year after rewetting. However, the spatial and temporal variability decreased, and high CH4 emissions, as reported for freshwater rewetting, did not occur. CO2 fluxes (mean ± SD) decreased slightly from 0.29 ± 0.82 g m−2 h−1 (pre-rewetting) to 0.26 ± 0.29 g m−2 h−1 (post-rewetting). The availability of organic matter (OM) and dissolved nutrients were likely the most important drivers of continued CO2 production. Pre-rewetting CH4 fluxes ranged from 0.13 ± 1.01 mg m−2 h−1 (drained land site) to 11.4 ± 37.5 mg m−2 h−1 (ditch). After rewetting, CH4 fluxes on the formerly dry land increased by 1 order of magnitude (1.74 ± 7.59 mg m−2 h−1), whereas fluxes from the former ditch decreased to 8.5 ± 26.9 mg m−2 h−1. These comparatively low CH4 fluxes can likely be attributed to the suppression of methanogenesis and oxidation of CH4 by the available O2 and sulfate in the rewetted peatland, which serve as alternative electron acceptors. The post-rewetting N2O flux was low, with an annual mean of 0.02 ± 0.07 mg m−2 h−1. Our results suggest that rewetted coastal peatlands could account for high, currently unmonitored, nutrient inputs into adjacent coastal water, at least on a short timescale such as a few years. However, rewetting with brackish water may decrease GHG emissions and might be favored over freshwater rewetting in order to reduce CH4 emissions.

РОЛЬ ГИДРОТЕРМАЛЬНОЙ ДИНАМИКИ В ЗАРОЖДЕНИИ ЖИЗНИ НА ЗЕМЛЕ

In framework of the inversion concept one more required condition for the origin of life has been substantiated: multilevel fluctuations of physic-chemical parameters (in addition to the three accepted: availability of organic matter, aqueous medium, and source of energy). Taking this condition into consideration, hydrothermal systems were preferable medium for the origin of life on early Earth, in comparison with ocean. Hydrothermal environments are characterized by an extremely wide range of temperature, pressure, pH, and concentrations of components gradients. Multilevel fluctuations availability has been corroborated by means of thermodynamic estimations and direct measurements of pressure and temperature during the monitoring in some of the Kamchatka peninsula hydrothermal systems. The monitoring database mathematical processing reveals at least three levels of pressure fluctuations: 1) irregular macro fluctuations (with big amplitudes); 2) regular micro oscillations (with smaller amplitudes and periods about 20 minutes); 3) sudden pressure changes and fluctuations with periods lower than 5 minutes. High correlation between pressure, temperature, and concentrations of chemical components is also detected both in hydrothermal systems of Kamchatka and Slovenia. A lot of data on pressure and temperature dynamics in hydrothermal fluid, obtained by many researchers, can be applicable for investigation of the origin-of-life process.

THE EFFECT OF CHICKEN MANURE AS ORGANIC MATTER AND NPK FERTILIZER ON GROWTH AND YIELD OF CABBAGE IN ALLUVIAL SOIL

Cabbage Flowers are flower buds in large numbers forming thick and dense circles. Utilization of alluvial soil as a growing medium is faced with low soil fertility, acidic soil pH, low levels of organic matter availability, and lack of nutrient content. The limited carrying capacity of the alluvial soil needs to be overcome by adding organic matter and nutrients needed to improve soil fertility as a growing medium for cauliflower plants. This study aims to determine the interaction of chicken manure as organic matter and NPK on the growth and yield of flower cabbage on alluvial soil. This research was conducted at Jalan Daya Nasional, Tanjungpura University Lecturer Complex, Pontianak from 27 December – 28 March 2022. This research is a field experiment with a factorial pattern of Completely Randomized Design (CRD) consisting of 2 factors. The first factor consisted of chicken manure (K) which consisted of 3 treatment levels and the second factor was NPK fertilizer (N) with 3 treatment levels. Each treatment combination was repeated 3 times and each experimental unit contained 4 sample plants, so there were 108 plants. The first factor is chicken manure which consists of 3 levels, namely: 108 ton/ha, 243 ton/ha and 378 ton/ha. The second factor is NPK fertilizer which consists of 3 levels, namely: 300 kg/ha, 450 kg/ha and 600 kg/ha. Observation variables include: number of leaves, root volume, dry weight of the top of the plant, fresh weight of flowers and flower diameter. The results showed that there was an interaction between chicken manure and NPK fertilizer on the variable number of leaves 4 WAP. The dose of 243 ton/ha and pupuk NPK 600 kg/ha fertilizer is an efficient dose to increase the growth of flower cabbage on alluvial soil. Keywords : Alluvial, Cabbage Flowers, NPK, Chicken Manure

RESPON PERTUMBUHAN BIBIT KELAPA SAWIT DI MAIN NURSERY AKIBAT KOMBINASI PUPUK KOTORAN AYAM DAN NPK PADA TANAH PMK

Seedlings of oil palm in the main nursery take place from the age of 4 to 12 months of seedlings, in that period the oil palm seedlings already need additional nutrients in the growing media. Utilization of PMK soil as a growing medium is faced with low soil fertility, low levels of organic matter availability, and lack of nutrient content. The limited carrying capacity of PMK soil needs to be overcome by adding organic matter and nutrients to improve soil fertility of PMK as a growing medium for nurseries in the main oil palm nursery. This study aims to determine the effect and dose of the best combination of chicken manure and NPK fertilizer on PMK soil for the growth of oil palm seedlings at the main nursery stage. The study was conducted in Ngabang, West Kalimantan on January 17, 2022 to May 17, 2022. This study used a field experiment method with a completely randomized design (CRD) one factor, namely a combination of chicken manure and NPK fertilizer. The combinations in question are A= Chicken manure 0 % + 100 % NPK, B= Chicken manure 20 % + 80 % NPK, C= Chicken manure 40 % + 60 % NPK, D= Chicken manure 60 % + 40 % NPK, E= Chicken manure 80 % + 20 % NPK, F= Chicken manure 100 % + 0 % NPK. The variables observed in this study were plant dry weight (g), root volume (cm3), plant height (cm), stem diameter (cm), and number of leaves (strands). The growth response of oil palm seedlings in the main nursery on the 100 % NPK treatment was better than the 100 % chicken manure treatment on the variables of plant height, stem diameter and equally good on the variables of plant dry weight, root volume and number of leaves. Treatment of 100 % NPK resulted in the highest average plant dry weight, root volume, plant height, stem diameter and number of leaves compared to other treatments.Keywords : chicken manure, main nursery, npk, red-yellow podzolic soil

Effects of nitrogen fertilizer on soil microbial residues and their contribution to soil organic carbon and total nitrogen in a rice-wheat system

Soil microbial residues have an impact on the stability of the soil organic carbon (SOC) pool, since they are crucial and stable sources of SOC. However, it is not clear how soil microbial residues in aggregates affect the SOC and total nitrogen (TN) at different gradients of N fertilization. Therefore, we investigated the effect of N fertilizer on microbial residues and their contribution to SOC and TN in soil aggregates under a rice-wheat (Oryza sativa-Triticum aestivum) system with four rates of N fertilizer. The results indicated that the addition of N fertilizer clearly increased the phospholipid fatty acids of bacteria and enhanced the activities of soil enzymes (β-1,4-glucosidase, β-N-acetyl-glucosaminidase and phenol oxidase) in the macroaggregates. The content of bacterial residual carbon increased noticeably when N fertilizer was added, while the content of fungal residual carbon did not appear to change. The addition of N fertilizer increased the contribution of bacterial residual carbon to SOC and TN. There was no significant difference in the contribution of bacterial residues on SOC and TN at different N fertilizer rates. Nevertheless, their contribution gradually decreased with the decrease in aggregate size. Structural equation modeling showed that the contribution of soil microbial residue to TN was influenced by activities of soil enzymes, suggesting that N is an important factor that affects soil ecology and limits the availability of nitrogenous organic matter in agroecological systems. This finding is crucial to understanding how N fertilizer influences soil C and N cycle in rice-wheat systems.

Efficient carbon and nitrogen transfer from marine diatom aggregates to colonizing bacterial groups

Bacterial degradation of sinking diatom aggregates is key for the availability of organic matter in the deep-ocean. Yet, little is known about the impact of aggregate colonization by different bacterial taxa on organic carbon and nutrient cycling within aggregates. Here, we tracked the carbon (C) and nitrogen (N) transfer from the diatom Leptocylindrus danicus to different environmental bacterial groups using a combination of 13C and 15N isotope incubation (incubated for 72 h), CARD-FISH and nanoSIMS single-cell analysis. Pseudoalteromonas bacterial group was the first colonizing diatom-aggregates, succeeded by the Alteromonas group. Within aggregates, diatom-attached bacteria were considerably more enriched in 13C and 15N than non-attached bacteria. Isotopic mass balance budget indicates that both groups showed comparable levels of diatom C in their biomass, accounting for 19 ± 7% and 15 ± 11%, respectively. In contrast to C, bacteria of the Alteromonas groups showed significantly higher levels of N derived from diatoms (77 ± 28%) than Pseudoalteromonas (47 ± 17%), suggesting a competitive advantage for Alteromonas in the N-limiting environments of the deep-sea. Our results imply that bacterial succession within diatom aggregates may largely impact taxa-specific C and N uptake, which may have important consequences for the quantity and quality of organic matter exported to the deep ocean.

Volumetric analysis of benthic foraminifera: Intraspecific test size and growth patterns related to embryonic size and food resources

Morphological variation in benthic foraminifera is often used to reconstruct paleoenvironmental conditions and infer their physiological responses to environmental change. Computed-tomographic imaging allows precise measurements of test volume, test surface area, and the internal volume of individual chambers, thus changes in morphology throughout ontogeny can used to test these morphology-environment relationships. Here, I examine morphological changes in five benthic foraminiferal species (Uvigerina peregrina, Buliminella tenuata, Loxostomum pseudobeyrichi, Bolivina argentea, and Bolivina seminuda) during a deglacial deoxygenation event recorded in marine sediments from the Gulf of Alaska to examine morphological responses to oxygenation. Although the mechanics of oxygen diffusion imply that benthic foraminifera should have higher surface area to volume ratios (SA/V) at low oxygen, specimens from the lowest oxygen conditions had lower SA/V due to their larger size. Examination of test volume through ontogeny indicates that specimens achieve large size by having a large initial chamber and not via higher growth rates. Thus, terminal size is a passive result of embryonic size. U. peregrina and B. tenuata have the strongest association between large size and low-oxygen and are sensitive to organic matter availability. The studied low-oxygen event was likely maintained by enhanced organic carbon export, which provided the resources to produce large offspring. Thus, the morphological changes observed along the paleo-oxygen gradient are likely related to food availability and the survival advantage of larger embryos in low-oxygen settings for some species. These results imply that size and SA/V in benthic foraminifera do not reliably reflect physiological responses to oxygenation.

Contrasting archaeal and bacterial community assembly processes and the importance of rare taxa along a depth gradient in shallow coastal sediments

Marine microbial communities assemble along a sediment depth gradient and are responsible for processing organic matter. Composition of the microbial community along the depth is affected by various biotic and abiotic factors, e.g., the change of redox gradient, the availability of organic matter, and the interactions of different taxa. The community structure is also subjected to some random changes caused by stochastic processes of birth, death, immigration and emigration. However, the high-resolution shifts of microbial community and mechanisms of the vertical assembly processes in marine sediments remain poorly described. Archaeal and bacterial communities were analyzed based on 16S rRNA gene amplicon sequencing and metagenomes in the Bohai Sea sediment samples. The archaeal community was dominated by Thaumarchaeota with increased alpha diversity along depth. Proteobacteria was the dominant bacterial group with decreased alpha diversity as depth increased. Sampling sites and depths collectively affected the beta-diversity for both archaeal and bacterial communities. The dominant mechanism determining archaeal community assembly was determinism, which was mostly contributed by homogeneous selection, i.e., consistent selection pressures in different locations or depths. In contrast, bacterial community assembly was dominated by stochasticity. Co-occurrence networks among different taxa and key functional genes revealed a tight community with low modularity in the bottom sediment, and disproportionately more interactions among low abundant ASVs. This suggests a significant contribution to community stabilization by rare taxa, and suggests that the bottom layer, rather than surface sediments may represent a hotspot for benthic microbial interactions.

Low biological phosphorus removal from effluents treated by slow sand filters.

The legislation for environment protection requires strict controls of the wastewater releasing in water bodies. The wastewater treatment plants (WWTP) have been used for organic matter degradation; however, the residual total phosphorus (TP) removal has not been efficient. TP and nitrogen present in wastewater are associated to eutrophication of water bodies and algae growth. Therefore, this study discusses the efficiency of phosphorus removal by a slow filter (SF), complementary to a WWTP and the microbial community involved. The results showed that the use of SF, with or without macrophytes, is not suitable to remove TP. Spatial variation in microbial communities distributed in three distinct zones was identified in the SF. Proteobacteria, Bacteroidetes, Chloroflexi and Firmicutes covered the hydrolytic and fermentative bacteria. The acetogenesis, nitrification, and denitrification, as well as the removal of phosphorus from the effluent, were performed by representatives affiliated to different groups. Alphaproteobacteria, Betaproteobacteria, and Gammaproteobacteria among these, Dokdonella sp., Frateuria sp., Comamonas sp., Diaphorobacter sp., Nitrosospira sp., Ferruginibacter sp., Flavobacterium sp., and the uncultured OD1 were the most abundant bacteria in the SF. The low efficiency for TP removing from SF effluents can be explained by the low abundance of phosphorus accumulating organisms (PAOs), with the association of the low concentration of biodegradable organic matter in the inlet effluent. Therefore, the alternative to using SF as a complement to WWTPs, as recommended by some Brazilian environmental agencies, did not prove to be viable and new approaches must be evaluated. KEY POINTS: • The phosphorus removal was performed by a slow filter system in a WWTP but obtained a low efficiency. • Microbial spatial variation was distributed into distinct zones from slow filter. • Low abundance of PAOs was observed due to the low availability of organic matter.

Effect of Humic Acid on the Growth and Metabolism of Candida albicans Isolated from Surface Waters in North-Eastern Poland.

The aim of this study was to determine the effect of humic acid on the growth and metabolism of Candida albicans, a common waterborne pathogenic yeast. At 10–20 mg/L, humic acid caused the greatest increase in biomass and compactness of proteins and monosaccharides, both in cells and in extracellular secretion of the yeast. At higher humic acid concentrations (40–80 mg/L), C. albicans cells still had higher protein levels compared to control, but showed reduced levels of metabolites and inhibited growth, and a significant increase in the activity of antioxidant enzymes, indicating a toxic effect of the humic acid. The increase in protein content in the cells of C. albicans combined with an increase in the activity of antioxidant enzymes may indicate that the studied yeast excels in conditions of high water enrichment with low availability of organic matter. This indicates that Candida albicans is capable of breaking down organic matter that other microorganisms cannot cope with, and for this reason, this yeast uses carbon sources that are not available to other microorganisms. This indicates that this fungus plays an important role in the organic carbon sphere to higher trophic levels, and is common in water polluted with organic matter.

Phosphorus control and dredging decrease methane emissions from shallow lakes

Freshwater ecosystems are an important source of the greenhouse gas methane (CH4), and their emissions are expected to increase due to eutrophication. Two commonly applied management techniques to reduce eutrophication are the addition of phosphate-binding lanthanum modified bentonite (LMB, trademark Phoslock©) and dredging, but their effect on CH4 emissions is still poorly understood. Here, this study researched how LMB and dredging affected CH4 emissions using a full-factorial mesocosm design monitored for 18 months. The effect was tested by measuring diffusive and ebullitive CH4 fluxes, plant community composition, methanogen and methanotroph activity and community composition, and a range of physicochemical water and sediment variables. LMB addition decreased total CH4 emissions, while dredging showed a trend towards decreasing CH4 emissions. Total CH4 emissions in all mesocosms were much higher in the summer of the second year, likely because of higher algal decomposition and organic matter availability. First, LMB addition lowered CH4 emissions by decreasing P-availability, which reduced coverage of the floating fern Azolla filiculoides, and thereby prevented anoxia and decreased surface water NH4+ concentrations, lowering CH4 production rates. Second, dredging decreased CH4 emissions in the first summer, possibly it removed the methanogenic community, and in the second year by preventing autumn and winter die-off of the rooted macrophyte Potamogeton cripsus. Finally, methanogen community composition was related to surface water NH4+ and O2, and porewater total phosphorus, while methanotroph community composition was related to organic matter content. To conclude, LMB addition and dredging not only improve water quality, but also decrease CH4 emissions, mitigating climate change.

Methane concentrations and fluxes in agricultural and preserved tropical headwater streams

Tropical streams have been intensively impacted by agricultural activities. Among the most important agricultural activities in Brazil, sugarcane production represents a large impact for economic development and for environmental conditions. Permeating sugarcane fields, several headwater streams can be affected by sugarcane cultivation, in special, aquatic biogeochemical cycles because of the deforestation, fertilization, crop residues and higher temperatures in the tropics. In this study, we analyzed the effects of sugarcane cultivation on methane fluxes and concentrations, assuming that carbon cycles are influenced by agricultural activities in headwater streams. Our study aimed to (1) measure methane fluxes and concentrations in tropical streams located in Southeastern Brazil, (2) Analyze whether seasonal cycles influence methane fluxes and concentrations, (3) Evaluate the influence of sugarcane cultivation on methane fluxes and (4) Analyze the association between water chemistry in the methane concentrations in tropical streams. We found mean fluxes of CH4 of 0.280 mmol m−2 d−1, with higher fluxes during the summer and in streams draining preserved catchments. The average CH4 concentrations were 0.695 μmol L−1, with higher values during the summer and in streams draining preserved catchments. Methane concentrations in the studied streams was influenced by dissolved oxygen (negatively), dissolved organic carbon (negatively), water velocity (positively) and conductivity (negatively). Methane concentrations were significantly higher than concentrations found in Temperate Grasslands, Savannas & Shrublands and similar to concentrations found in other tropical biomes (excluding Tropical & Subtropical Moist Broadleaf Forests which receives large amounts of organic inputs). We conclude that sugarcane influence methane concentrations and fluxes in tropical streams by reducing the organic matter availability provided by the native vegetation in soil and water.

Organic matter availability drives the spatial variation in the community composition and activity of Antarctic marine bacterioplankton.

Carbon cycling by Antarctic microbial plankton is poorly understood but it plays a major role in CO2 sequestration in the Southern Ocean. We investigated the summer bacterioplankton community in the largely understudied Weddell Sea, applying Illumina amplicon sequencing, measurements of bacterial production and chemical analyses of organic matter. The results revealed that the patchy distribution of productive coastal polynyas and less productive, mostly ice-covered sites was the major driver of the spatial changes in the taxonomic composition and activity of bacterioplankton. Gradients in organic matter availability induced by phytoplankton blooms were reflected in the concentrations and composition of dissolved carbohydrates and proteins. Bacterial production at bloom stations was, on average, 2.7 times higher than at less productive sites. Abundant bloom-responsive lineages were predominately affiliated with ubiquitous marine taxa, including Polaribacter, Yoonia-Loktanella, Sulfitobacter, the SAR92 clade, and Ulvibacter, suggesting a widespread genetic potential for adaptation to sub-zero seawater temperatures. A co-occurrence network analysis showed that dominant taxa at stations with low phytoplankton productivity were highly connected, indicating beneficial interactions. Overall, our study demonstrates that heterotrophic bacterial communities along Weddell Sea ice shelves were primarily constrained by the availability of labile organic matter rather than low seawater temperature.

Effects of common European tree species on soil microbial resource limitation, microbial communities and soil carbon

Studies of tree species effects on soils have revealed a significant impact on soil organic carbon (SOC) stocks and the carbon (C) distribution between forest floor and mineral soil, but the underlying mechanisms including the roles of litter traits, soil properties, and microbiome remain unclear. To address this challenge, we tested the effect of six common European tree species on the quality and nutrient availability of soil organic matter (SOM) as perceived by the naturally assembled microbial communities and explored the possible links between soil enzyme activities (EAs), microbial resource limitation, and microbial community with SOC stocks. The six studied tree species (Acer pseudoplatanus L., Fraxinus excelsior L, Fagus sylvatica L., Quercus robur L., Tilia cordata L., and Picea abies L.) were planted in common garden monocultures more than 40 years ago at six sites across Denmark. In forest floor, microbial biomass C, fungal and total microbial biomass and fungi to bacteria (F/B) ratios decreased with decreasing litter quality. Ecoenzymatic stoichiometry and relative EAs indicated that microbes in spruce forest floor were more limited by phosphorus (P) than in maple, lime, and beech, while microbes in mineral soils were less P limited in spruce than in other monocultures. Mineral soil under the tree species associated with arbuscular mycorrhizal (AM) fungi had higher microbial C and P limitation, bacterial biomass and total microbial biomass than under tree species associated with ectomycorrhizal (EcM) fungi. Our results indicated that tree species with high-quality litter (i.e. AM-associated trees) had (i) higher microbial biomass and less nutrient limitation that were conducive to higher decomposition rates and lower C stocks in the forest floor, and (ii) such tree species could lead to both greater stabilization of mineral soil C by mineral-associated OM formation and greater microbial mineralization of SOM with higher microbial resource demand. The results suggest that tree species-mediated EA, microbial resource limitation and microbial community composition are important drivers of stocks and vertical distribution of SOC among tree species and between the two types of associated mycorrhiza.

Differential response of tree species from Brazilian tropical dry Forest (Caatinga) to phosphorus doses associated with organic matter

The availability of phosphorus (P) and organic matter in Chromic Luvisols, predominant in the Caatinga biome, is generally low and makes it difficult to reintroduce native plants in forest recovery projects. The objective was to evaluate the production of dry mass, accumulation a and use efficiency of P by three tree species native from Caatinga biome with application of doses of P and organic matter. This experiment was carried out in a greenhouse in a completely randomized design in a 2 × 3 × 5 factorial scheme, consisting of with two doses of organic matter (0 and 50 g kg−1), three species of plants (Tabebuia aurea (Silva Manso) Benth. & Hook.f. ex S Moore, Amburana cearensis, Allemão AC Smith and Caesalpinia ferrea Mart. Ex Tul.) and five doses of P (0, 50, 100, 150 and 200 mg dm−3). At 120 days after transplanting, concentrations of P available in the soil and leaf soluble P fractions increased linearly with the P doses. The availability of P in the soil and, consequently, the accumulation of soluble and total P in the plant tissues were greater with organic matter application. The studied species use different P compartmentalization strategies depending on their dry mass production capacity. Phosphate and or organic matter application is necessary in the initial growth phase of the studied species, notably T. aurea and C. ferrea. The dry mass of T. aurea was greater than that of C. ferrea and A. cearensis.

Geographic patterns of soft-bottoms benthic communities in Chilean Patagonian fjords (47°S-54°S) - influence of environmental stress on diversity patterns and stable isotope signatures

The benthic community in the Chilean Patagonia is as rich and highly diverse as the spatial variation of its habitats and food sources. Environmental stress from glacier melt and river discharge are known drivers of benthic community dynamics. Here, we analyze longitudinal patterns of soft-bottom benthic communities across transects of glacier-marine environments and how these habitats may respond to changes in the environmental conditions. To assess the relationships between environmental heterogeneity (marine and glacial habitats) and benthic biodiversity, this paper reviews biological (mega- and macroinfauna) and sedimentological dataset from multiple oceanographic campaigns in Chilean Patagonian fjords. Furthermore, we analyze isotopic compositions of epibenthic and macroinfaunal organisms (δ13C/δ15N and C/N) to determine particulate organic carbon (POC) and particulate organic nitrogen (PON) availability and organismal stoichiometric budgets within each benthic community. Our results showed that glaciomarine and glaciofluvial environmental stress negatively affected nutrient reservoirs and organic matter (OM) availability, and hence produced changes in benthic diversity and trophic structure throughout the fjords. These conditions shaped the benthic community where small-bodied polychaetes and opportunistic species dominated. Additionally, we found a strong relationship between OM and nutrient availability with faunal isotopic composition, but a decoupling in C/N ratios between fauna and sediment OM, suggesting preferential organic carbon use under limited nitrogen in fjord sediments.

High-frequency modification of the central Mediterranean seafloor environment over the last 74 ka

Here we present a high-resolution record of benthic foraminiferal assemblages for the last 74 kyr from the Sicily Channel Ocean Drilling Program Leg 160 Site 963. Benthic foraminiferal results are compared with geochemical (benthic and planktic δ 18 O and δ 13 C) and calcareous plankton data, previously acquired on the same marine core sediments. Within the succession, three benthic foraminifera compositional zones were defined. Temporal changes in the assemblages are interpreted in the context of the modification of subtropical and temperate climate systems that affected the Mediterranean thermohaline circulation. A close connection between bottom conditions in the Sicily Channel and eastern Mediterranean Sea is evident in two intervals, characterized in the ODP Site 963 by reduced oxygen conditions. The first one, around 53–51 ka, is tentatively attributed to the ‘missing’ sapropel S2 while the second, between 35 and 29 ka, is marked by short and recurrent episodes of bottom-water oxygen decrease. Both are related to a weakening of the intermediate circulation in the Sicily Channel connected with relatively high northern hemisphere summer insolation and increase in Nile River discharge, which inhibited vertical mixing and intermediate water ventilation in Eastern Mediterranean Sea. Over the last deglaciation, the African humid period (AHP) and the sea level rise, also influenced the water mass structure in the Sicily Channel and a reduction of the bottom ventilation is suggested by a strong reduction of deep-water Miliolids. Decreased bottom oxygen levels, which testifies for a weakening of intermediate circulation in Sicily Strait, also characterized the interval corresponding to S1 deposition. Yet, the strong decrease of benthic foraminiferal abundance related to a low surface water trophic level, appears to be conditioned by the reduction of trophic levels in the western Mediterranean. The very high relative abundance of U. mediterranea recorded during this interval is explained by the availability of organic matter during a limited short year period and/or the availability of more degraded organic matter from river runoff. In general, compositional data analysis highlighted a quite complex response of benthic foraminifera to paleoclimatic changes. However, changes in the benthic foraminiferal assemblages recorded during the last glacial are coherent with surface paleoproductivity dynamics connected with D-O oscillation, and support oligotrophic, meso-eutrophic and oligo-mesotrophic conditions during the early interstadials, late interstadials and stadials, respectively. • High-resolution ODP963 (Sicily Channel) Last Glacial to Holocene benthic record. • Dansgaard-Oeschger imprints in bottom environments. • Connection between western and eastern Mediterranean dynamics. • Relationships between Levantine Intermediate Water flow and bottom ventilation.

Perbandingan Sistem Resirkulasi dan Air Mengalir Untuk Pembesaran Lobster Pasir (Panulirus Homarus): Kajian Dinamika Kualitas Air

Aquaculture with the Recirculation Aquaculture System (RAS) is a unique engineered ecosystem that minimizes environmental disturbances by reducing the discharge of nutrient pollution through reuse of water used in fish farming. This activity was conducted at LP2IL Serang field test facility starting in June-November 2020. In this test, the RAS system used for growing of sand lobster uses the stages of purification: sedimentation, physical filtration, biological filtration, water disinfection with UV irradiation, removal of CO2, clean water reservoirs and sand lobster rearing tanks. Water quality parameters tested: a) physics: DO, pH, temperature and salinity are measured every day; b) chemistry: ammonia (TAN and UIA), nitrite, nitrate and phosphate are measured every two weeks. If from the UIA value calculation, the value is above the quality standard (> 0.05 mg / L) then added molasses (26.02% organic C) with a concentration of 64 gr / gr TAN; c) microbiology: total bacteria and Vibrio sp. counting. From the results of this study it is known that RAS can maintain stable water quality for a relatively long time. High availability of organic matter (from leftover feed, feces and addition of molasses) can promote the growth of nitrifying bacteria. The "maturation" of the nitrifying bacteria in the biofilter compartment takes about 6 weeks. These bacteria are able to reduce levels of ammonium nitrogen, where the accumulation of nitrate nitrogen (NO3-) which is produced from the overhaul of nitrite nitrogen (NO2-) by nitrifying bacteria, is a signal that the maturation process of nitrifying bacteria has been achieved. The nitrification process consumes alkalis, hence lowers the pH value in the water, besides it also consumes a large amount of oxygen. The low number of bacteria and vibrio in the RAS system was affected by the use of a UV-sterilizer with a wavelength of 254 nm.

Tracing glacial-interglacial water mass changes in the Gulf of Corinth (IODP Expedition 381) using iron-sulphur geochemistry and magnetic susceptibility

The Gulf of Corinth is a rapidly rifting basin that has been alternately connected to/isolated from the Mediterranean due to Quaternary global sea levels fluctuations. A recently retrieved sediment record from the Gulf of Corinth (IODP Expedition 381) shows variations in magnetic susceptibility, with relatively higher and more variable values in isolated/glacial sediments and lower, more stable values in connected/interglacial sediments. Using geochemical methods, we find that not the primary input of magnetic minerals, but diagenetic processes generated the magnetic susceptibility pattern. Easily reducible sulphides (most likely greigite) increase in high magnetic susceptibility (isolated/glacial) sediments, whilst magnetite shows no systematic relationship to magnetic susceptibility. After discounting several possible causes for the formation and preservation of greigite (bottom water redox conditions, high sedimentation rates, reactive Fe and organic matter availability), a decrease in sulphate concentrations in the Gulf of Corinth during isolated/glacial periods is the most likely explanation, supporting parallel microfossil evidence for a freshening of the water column. This sulphate limitation appears to stall sedimentary pyrite formation at the stage of ferrimagnetic monosulphides like greigite. Greigite formation as an indicator of paleosalinity variations has been observed in other depositional settings (e.g., Chesapeake Bay, the Baltic Sea, the Miocene Paratethys and the Black Sea), supporting our interpretation. Specific to the Gulf of Corinth, linking a proxy for basin connectivity to a high resolution (at least 40, and up to 7 year temporal resolution) magnetic susceptibility record over 750,000 years offers an opportunity to investigate, in detail, the tectonic evolution of this rift basin and its link to global sea level fluctuations.

Low carbon availability in paleosols nonlinearly attenuates temperature sensitivity of soil organic matter decomposition.

Temperature sensitivity (Q10 ) of soil organic matter (SOM) decomposition is an important parameter in models of the global carbon (C) cycle. Previous studies have suggested that substrate quality controls the intrinsic Q10 , whereas environmental factors can impose large constraints. For example, physical protection of SOM and its association with minerals attenuate the apparent Q10 through reducing substrate availability and accessibility ([S]). The magnitude of this dampening effect, however, has never been quantified. We simulated theoretical Q10 changes across a wide range of [S] and found that the relationship between Q10 and the log10 -transformed [S] followed a logistic rather than a linear function. Based on the unique Holocene paleosol chronosequence (7 soils from ca. 500 to 6900years old), we demonstrated that the Q10 decreased nonlinearly with soil age up to 1150years, beyond which Q10 remained stable. Hierarchical partitioning analysis indicated that an integrated C availability index, derived from principal component analysis of DOC content and parameters reflecting physical protection and mineral association, was the main explanatory variable for the nonlinear decrease of Q10 with soil age. Microbial inoculation and 13 C-labelled glucose addition showed that low C availability induced by physical protection and minerals association attenuated Q10 along the chronosequence. A separate soil incubation experiment indicated that Q10 increased exponentially with activation energy (Ea ) in the modern soil, suggesting that SOM chemical complexity regulates Q10 only when C availability is high. In conclusion, organic matter availability strongly decreased with soil age, whereas Michelis-Menten kinetics defines the Q10 response depending on C availability, but Arrhenius equation describes the effects of increasing substrate complexity.