Variability Of Organic Matter Research Articles

The Performance of Oil Palm Productivity and Management of Organic Materials at Various Rain Intensity in Sandy Soil

Climate anomalies marked by the presence of el Nino and la Nina need attention in managing oil palm plantations. These conditions have a bad influence on water conditions, especially in sandy land. The application of empty fruit bunches as organic matter source is expected to reduce the adverse effects of la Nina on palm oil production. This study aims to reveal variations of rainfall intensity and organic matter on the productivity of oil palm in sandy land. Results shows that the application of empty bunches accompanied by vegetation management is useful in maintaining the condition of the sand in holding water on one side and controlling excess water on the other side for 24 months (2011-2012). The application has succeeded in increasing production 23% higher than its potential yield in sandy soil with annual high rainfall (3,700 mm).

Impacts of long-term land use on terrestrial organic matter input to lakes based on lignin phenols in sediment records from a Swedish forest lake

Organic carbon burial in lake sediments plays an important role in the global carbon cycle, and is heavily affected by the terrestrial organic matter input. However, few studies have focused on long-term changes in terrestrial organic matter input to lakes in response to land-use changes. The aim of this study was to assess variations in sedimentary terrestrial organic matter over the last 1000 years based on lignin biomarker records from two sediment cores from Lake Skottenesjön, southwestern Sweden. In combination with pollen-based quantitative land cover reconstruction, we investigated the impacts of centennial-scale land-use changes on terrestrial organic matter input to lake sediments. The results show that human activities in the catchment had significant impacts on terrestrial organic export by modifying the vegetation cover. Intensified use of the forest in the 18th and 19th centuries led to enhanced soil erosion, and increased terrestrial organic matter input to the lake. Although farmland expanded between the 12th and the middle of 14th century, no significant change in terrestrial organic matter input was observed at that time. Much higher export of terrestrial organic and minerogenic matter to the lake was observed during the period of modern forestry in the 20th century as compared to previous periods of minor forest disturbance, such as 11th century. The changes in the vegetation cover in the catchment considerably modified the composition of terrestrial organic matter deposited in the lake sediments, which is reflected by the composition of lignin phenols. This study demonstrates that the combination of lignin phenols analysis and pollen-based quantitative land cover reconstruction is a useful approach for investigating long-term changes in terrestrial organic matter delivery to lake ecosystems.

Growth performance, nutrient intake and digestibility of goats fed melon husk and palm oil slurry at 30% inclusion level

A 126-day study was conducted to determine growth, nutrient intake and digestibility of West African Dwarf (WAD) goats fed melon husk (MH) and palm oil slurry (POS) as replacement for maize offal at 30% in concentrate diets. Sixteen goats weighing 6.5 – 7.Okg were randomly assigned to 4 dietary treatments at 4 replicates of each. Dietary treatments included control (Diet 1): 0% MH 0% POS; Diet 2: 30% MH 0% POS; Diet 3: 0% MH 30% POS; and Diet 4: 30% MH 30% POS; supplemented with Panicum maximum (grass). Data collected were statistically analysed and results showed that animals on control Diet (Diet I) had the highest (P<0.05) average daily weight gain of 31.57g/day, and a corresponding highest (P<0.05) feed intake of 365. 97g/day and best feed conversion ratio of 11.59. Animals fed Diet 3 had lowest (P<0.05) average daily weight gain of 19.42g/day, with corresponding lowest (P<0.05) dy matter intake of 334.94g/day and poor feed conversion ratio of 17.24, respectively. Variations in dry matter, organic matter and crude fibre (CF) intake were significant (P<0.05). Crude protein (CP) intake decreased progressively from diet 1 to 4, but not significantly (P >0.05). CF intake was highest in diet 4 (124.6g) and lowest in diet 1(64.72g). Ether extract (52.80g), Ash (21.48g), Neutral detergent fibre (222.88g), and lignin (60.64g) were highest in diet 4. Dry matter digestibility was highest in animals on diet 2 (86.31%) and lowest in those on diet 4 (72.28%). It was evident that goats could be fed MH and POS at the inclusion levels adopted in this study except at 30% POS inclusion level at which growth was poorest.

Variation and Reactivity of Organic Matter in the Surface Sediments of the Changjiang Estuary and Its Adjacent East China Sea

AbstractThe Changjiang Estuary and its adjacent sea make up a highly dynamic ecosystem where the processes influencing the sources and degradation of organic matter (OM) in sediments are still not well understood. In this study, we analyzed the total organic carbon (TOC), total nitrogen (TN), stable carbon isotope (δ13C), and total hydrolysable amino acids (THAA) to investigate the distribution and degradation of sedimentary organic matter (SOM). TOC and TN contents ranged from 0.13% to 0.93% and 0.03% to 0.15%, respectively, with elevated values occurring in the muddy areas near the estuary. The δ13C of SOM became increasingly enriched from inshore (−23.5‰) to offshore (−20.5‰), and the TOC/TN molar ratios (C/N ratios) decreased from 8.16 to 5.84, indicating increasing contributions of marine OM. As the labile fraction of bulk OM, THAA concentrations ranged from 1.36 to 11.76 μmol/g and the distribution of THAA was influenced by terrestrial inputs along with the complex hydrography. The δ13C values and C/N ratios indicated that the SOM in the study area was mainly from marine and terrestrial origins (soil derived). The relatively low degradation index (DI) of SOM (mean: −0.57 ± 0.36) indicated that the OM had already undergone extensive degradation. Consistent with previous findings, our results indicated that the degraded OM was adsorbed by fine‐grained particles and selectively transported southward along the coast. The fresh SOM in the sandy area was mainly from in situ production. Additionally, diatoms appeared to be the primary source of the fresh OM buried in the sediments of the study area.

Changes of carbon-isotope ratios in soil organic matter relative to parent vegetation and site specificity

Investigating the correlation between biodiversity and ecosystem function in natural environments using carbon-isotope composition (δ13C) allows distinguishing the nutrient cycling pattern and anthropogenic effects incorporation in plants and soil processes. The mechanisms behind the isotopic composition of soil organic matter (SOM) and parent vegetation in relation to the context of site-specificity was approached in this work. Formation of SOM can be affected by the presence of a high concentration of heavy metals in soils. Still, no systematic studies were performed in most of the industrial sites to support this hypothesis. In order to explore this incomplete understood influence, investigation of carbon isotope signatures (d13C) variations in soil organic matter were performed in two industrial areas from Romania (Copșa Mică industrial platform and Baia Sprie mining zone). The current study, also, investigated the C:N ratio variation, as well as the influence of N speciation regarding d13C values of SOM. The decrease in C:N ratio indicated an increasing effect of the microbial products on SOM matter at increasing depth, for both regions, while an increase of the denitrification processes with depth was found for both areas. For the most appropriate depth (20-40 cm), the soil from Baia Sprie region was more enriched in 13C comparing with the soil from Copsa Mica region, and this higher isotope fractionation of SOM might be due to a higher carbon content, respectively a higher nitrogen content of Baia Sprie soil. It was concluded that the SOM of the surface soil in the two investigated regions has an 13C isotopic composition similar to the plant remains from which it was formed, offering an integrated value of plant material, time and the local origin and providing useful markers of tree isotopic composition.

Carbon Isotope Composition and Its Variation of Particulate Organic Matter in River Waters from the Kuzuryu River System

Radioactive and stable carbon isotopes (14C and 13C) can serve as powerful tools for studying the dynamics of organic matter in aquatic systems. This study considered the transport of particulate organic matter in a river system, a main river and its tributary with different watershed conditions, using carbon isotopic signatures. The Kuzuryu River system is located at Fukui and Gifu Prefecture in the central part of Japan, and consists of a main river, Kuzuryu River, and its main tributary, the Hino River. River research was conducted at a fixed station in the lower reaches of both rivers during June to October in 2010. Suspended solid samples were collected from 85 L to 141 L of river water using a continuous-flow centrifugation. δ13C of organic matter in riverine suspended solids had –26.3‰ to –24.0‰ for the Kuzuryu River and –27.0‰ to –26.1‰ for the Hino River. The Δ14C values of the Kuzuryu and Hino samples were –168‰ to –87‰ and –209‰ to –143‰, respectively. The Δ14C values of Hino River were depleted in 14C rather than the Kuzuryu River. However, the carbon isotopes have correlations with the water level for both rivers. The differences in the particulate organic matter characteristics are explained by the distribution of paddy fields and forests in each watershed, and the differences in the supply of suspended solids from their watershed due to rainfall.

Environmental Effects on Carbon Isotope Discrimination from Assimilation to Respiration in a Coniferous and Broad-Leaved Mixed Forest of Northeast China

Carbon (C) isotope discrimination during photosynthetic CO2 assimilation has been extensively studied, but the whole process of fractionation from leaf to soil has been less well investigated. In the present study, we investigated the δ13C signature along the C transfer pathway from air to soil in a coniferous and broad-leaved mixed forest in northeast China and examined the relationship between δ13C of respiratory fluxes (leaf, trunk, soil, and the entire ecosystem) and environmental factors over a full growing season. This study found that the δ13C signal of CO2 from canopy air was strongly imprinted in the organic and respiratory pools throughout C transfer due to the effects of discrimination and isotopic mixing on C assimilation, allocation, and respiration processes. A significant difference in isotopic patterns was found between conifer and broadleaf species in terms of seasonal variations in leaf organic matter. This study also found that δ13C in trunk respiration, compared with that in leaf and soil respiration, was more sensitive to seasonal variations of environmental factors, especially soil temperature and soil moisture. Variation in the δ13C of ecosystem respiration was correlated with air temperature with no time lag and correlated with soil temperature and vapor pressure deficit with a lag time of 10 days, but this correlation was relatively weak, indicating a delayed linkage between above- and belowground processes. The isotopic linkage might be confounded by variations in atmospheric aerodynamic and soil diffusion conditions. These results will help with understanding species differences in isotopic patterns and promoting the incorporation of more influencing factors related to isotopic variation into process-based ecosystem models.

Effects of minerals on metamorphism of organic matter during thermal processes in meteorite parent bodies

Molecular structures and chemical compositions of organic matter in primitive meteorites reflect the conditions of the parent bodies, as well as the preaccretional history. During the parent body processing, co-existing minerals could have effects on structural changes of organics, in addition to temperature and redox state. Here, we performed heating experiments of a primordial organic matter analog with and without minerals to understand the effects of minerals on organic matter in conditions simulating metamorphism in thermally metamorphosed type 3 chondrites. The primordial analog materials were heated up to 400 °C, and the experimental products were analyzed using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and gas chromatography mass spectrometry (GC/MS). Montmorillonite and olivine, particularly montmorillonite, enhanced decomposition of oxygen containing species due to decarboxylation and/or cracking, while olivine enhanced esterification at lower temperature. Our results further imply that the variations of insoluble organic matter in CV, CO, and type 3 ordinary chondrites could be partially due to different mineral compositions. We also tested the effects of pressure on the degradation of the organic matter at 400 °C up to 268 atm, however no significant pressure effects were observed by FTIR and GC/MS.

Synergistic co-digestion of waste commercial yeast and chicken manure: Kinetic simulation, DOM variation and microbial community assessment

Abstract Co-digestion of waste commercial yeast (Saccharomyces cerevisiae) and chicken manure was investigated in batch tests. The objective was to explore potential synergistic effects of the combination substrates. The biogas production rate and biomethane yield, batch kinetic simulation, metabolic dynamic and microbial community comparison were evaluated, respectively. The maximum biomethane yield of 364.79 mL/gVS was obtained at the optimum co-digestion feedstock (S.cerevisiae of 0.69 g/gVS) with a significant reaction rate increased of hydrolysis, acidogenesis, acetogenesis and methanogenesis. Person’s correlation analysis resulted that the dissolved organic matter (DOM) variation had a close correlation with indexes of NADH, NH4+-N, COD, VFAs and F420. The high-throughput sequencing showed that higher diversity was obtained both bacteria and archaea in the optimized condition with more abundant of synergistic bacteria. Moreover, community dynamic reflected that the abundances of hydrogentrophic Methanobacterium and Methanolinea raised from 11.74%, 0.23%–14.49%, 60.78%, respectively. While the proportion of the acetoclastic Methanosaeta was decreased from 88.04% to 24.72% with the increasing of S.cerevisiae dosages from 0.48 g/gVS to1.07 g/gVS.

Variation in Tree Growth along Soil Formation and Microtopographic Gradients in Riparian Forests

Policy makers are interested in managing forests to store carbon. Optimizing this strategy requires understanding how carbon storage varies across environmental gradients. We explored variation in tree growth rate, tree longevity, and surface soil organic matter across 135 Connecticut River riparian forest plots. Tree growth rate did not vary significantly with climate but rather increased with sediment accretion rate, soil pH and decreased with plot elevation, where elevation was measured relative to the stage of the 2-year flood. By contrast, surface soil organic matter was negatively related to pH and tree growth rate. Tree species longevities were greater at higher elevations with coarser soils. The faster growth rates at lower elevations allow for restoring forest structure rapidly, whereas flood intolerant but longer-lived tree species allow more durable carbon sequestration at higher elevations. The close associations of growth rate, sediment accretion, and pH suggest that riverine nutrient inputs are important to maintaining the exceptionally high productivity of floodplains. Environmental assessments of river dams should consider impacts of intercepting sediments and reducing flooding on downstream floodplain fertility and productivity. Restoration of riparian locations with high deposition of sediments and associated nutrients may be an opportunity to maximize both nutrient and carbon sequestration.

Source rock evaluation of the Cenomanian Raha Formation, Bakr oil field, Gulf of Suez, Egypt: Observations from palynofacies, RGB-based sporomorph microscopy, and organic geochemistry

The Gulf of Suez area in eastern Egypt is one of the most prospective and promising hydrocarbon provinces all over the world. Sixty drill cuttings samples of the Upper Cretaceous Raha Formation (70–120 m) have earlier been processed for their palynomorph and palynofacies contents, including 36 geochemically screened samples for their source-rock potential using TOC, Rock-Eval®. 6 Turbo, the new Rock-Eval® 7S instrument along with one of its latest modules, the CleanSim method. The combination between visual palynofacies and RGB-based sporomorph color image analysis along with the geochemical results are presented as part of a detailed assessment of the organic matter (OM) types, OM-richness, and thermal maturity levels.Palynofacies analysis defined three associations of OM types. The first and third associations consist of kerogen Type II; the former is dominated by a moderate abundance of amorphous organic matter (AOM) and phytoclasts, whilst the latter is dominated by high AOM content. Conversely, the second association is dominated by terrigenous fragments of gas-prone Type-III kerogen. The application of RGB analysis indicated a thermally immature to mature stage for some intervals in one of the three studied wells, the B-109.Geochemical screening results led to divide the Raha Formation into three distinctive groups, which are characterized by varied OM qualities and quantities, hydrocarbon potential, and thermal maturity levels.Varied thermal maturity levels was related directly to the Late Cretaceous tectonics like the effect of Syrian Arc System and the Oligocene-Miocene syn-rift activity that led to the opening of the Gulf of Suez. Differences in kerogen types were observed between geochemical and palynofacies analyses. Microscopic investigations of palynofacies-dominated AOM suggested that most AOM particles were of terrigenous origin due to the effect of biodegradation and gradual transformation of phytoclasts into AOM, reflecting a kerogen Type III instead of kerogen Type II that was indicated by palynofacies analysis ternary plots.

Organic matter variation within Upper and Lower Bakken shales of the Williston Basin by extracting kerogen pyrogram information

Activation energy distribution from kerogen kinetics study contains some integral characteristics of the host source rock thermal history over geological time scales. Extracting relevant information from pyrogram is critical for reconstruction of source rock maturation and hydrocarbon generation histories. In this study, in order to improve understanding of the Bakken shale source rock, we present a new quantitative kinetic model by inversion of Rock-Eval pyrograms of the Bakken Formation in Williston Basin. A group of core samples from both Upper and Lower Members of the Bakken Formation were collected for estimating transformation ratio (TR) and pyrolysis analysis, and an inversion method with different kinetic statistic parameters was designed and conducted using the source rock Tmax-Hydrogen Index covariation combined with different burial histories. The analysis of Rock-Eval results on Williston Basin samples from both Canada and US sides demonstrate basin-wide organic matter characteristics of Upper and Lower Bakken and identify variation of hydrocarbon generation histories. The Upper and Lower Bakken shales have different kerogen type characteristics based on activation energy distributions derived from Tmax-HI pair relationship, which suggest variance of the preserved algal materials for Upper and Lower Bakken. The modeling results by the thermal history analysis with the Rock-Eval dataset indicate a higher remanent generable kerogen in Lower Bakken shale, and the thermal maturity results will be valuable for integrated assessment of the hydrocarbon systems of Williston Basin accurately.

Tertiary denitrification and organic matter variations of secondary effluent from wastewater treatment plant by the 3D-BER system

A three-dimensional biofilm-electrode reactor (3D-BER) was constructed to facilitate the tertiary denitrification of the secondary effluent of wastewater treatment plants (SEWTP) under 12 mA and in the absence of a carbon source. The TN removal efficiency was 63.8%. The path of the formation and transformation of nitrogen, the relationship between the TN and COD removal rate and the relative concentration and composition of organic matter in the influent and effluent were analyzed to clarify the possible pathways of N and C transformation in the 3D-BER system. Under the action of an electric current, 4.4 mg NH4+-N·L−1 and 17.7 mg COD·L−1 accumulated in the 3D-BER system, and the removal rates of TN and COD were strongly and positively correlated (R2 = 0.9353). The microorganisms in the 3D-BER system under the action of electric current secreted organic matter, some of which (humic acid and microbial metabolites) could be further electrolyzed by microorganisms into bioavailable organic matter for heterotrophic denitrification. Partially dissolved organic matter (DOM, tryptophan aromatic protein, humic acid and microbial metabolites) in the SEWTP could be hydrolyzed under the action of the electric current in the 3D-BER system and consisted of bioavailable organic matter for heterotrophic denitrification. The contribution of heterotrophic denitrification to TN removal was greater than 11.7%. Therefore, the 3D-BER system removed a portion of DOM through microbial electrohydrolysis and promoted the coupling of hydrogen autotrophic denitrification and heterotrophic denitrification to enhance the effectiveness of nitrogen removal in SEWTP. Overall, this technique is effective for enhancing tertiary denitrification in SEWTP.

Measured and modelled source water δ18O based on tree-ring cellulose of larch and pine trees from the permafrost zone

Abstract: To identify source water for trees growing on permafrost in Siberia, we applied mechanistic models that quantify physical and biochemical fractionation processes, leading to oxygen isotope variation (δ18O) in plant organic matter. These models allowed us to investigate the influence of a variety of climatic factors on tree-ring cellulose from two dominant species: Larix cajanderi Mayr. from northeastern Yakutia (69° 22′ N, 148° 25′ E, ~ 250 m a.s.l.) and Pinus sylvestris L. from Central Yakutia (62°14′ N, 129°37′ E, ~ 220 m a.s.l.). The climate of the region is highly continental with short growing seasons, low amount of precipitation and these forest ecosystems are growing on permafrost, which in turn impact the water cycle and climate variation in the δ18O of source water. We compared outputs of the Land surface Processes and eXchanges (LPX-Bern v. 1.3), and Roden-Lin-Ehleringer (RLE) models for the common period from 1945 to 2004. Based on our findings, trees from northeastern and central Yakutia may have access to additional thawed permafrost water during dry summer periods. Owing to differences in the soil structure, active thaw soil depth and root systems of trees at two Siberian sites, Larix cajanderi Mayr. trees can access water not more than from 50 cm depth, in contrast to Pinus sylvestris L. in Central Yakutia which can acquire water from up to 80 cm soil depth. The results enhance our understanding of the growth and survival of the trees in this extreme environment.

The Influence of Depth on Soil Chemical Properties and Microbial Respiration in the Upper Soil Horizons

Soil microbial respiration is a biological process that converts soil organic matter into atmospheric CO2 via soil microorganisms. It reflects the overall metabolic activity of soil microbial populations and usually used as an indicator of soil health. Soil chemical properties, among others, have an influence on a catabolic capacity of the soil and greatly vary among different soil layers. In this study, we examined patterns of chemical soil properties and soil microbial respiration along 0–10 and 10–25 cm depths of the soil to investigate if soil depth had any effects on soil chemical properties and how these changes with depth could shift the soil microbial respiration. We employed basal respiration method to estimate the rate of soil microbial respiration and measured important chemical properties using standard protocols. The results showed differential effects of soil depth on chemical properties where available nitrogen ( $${\text{NH}}_{{\text{4}}}^{{\text{ + }}}$$ –N, $${\text{NO}}_{3}^{ - }$$ –N, and total N), cation exchange capacity, and Mg2+ were strongly influenced by soil depth. Soil microbial respiration greatly differed among the two soil depths (p = 0.0005) with a higher rate of soil microbial respiration in surface soils compared to subsurface soils. Soil microbial respiration had a significant positive correlation with total N, $${\text{NO}}_{3}^{ - }$$ –N, $${\text{NH}}_{{\text{4}}}^{{\text{ + }}}$$ –N, and soil organic matter (r = 0.98, 0.974, 0.9625, and 0.9455, respectively). The variation of soil microbial respiration was closely linked with the variation of soil organic matter and available nitrogen, implying that these variables were the key drivers of the variation of soil microbial respiration in the study area. Overall, the study highlighted that soil quality assessments and managements should include the depth effects to provide a better understanding of the dynamics of microbial respiration in the soil.

Distribution Characteristics and Migration Rules of Pollutants in Sediments of Reservoirs with Eucalyptus Plantation, Southern China

The safety of water quantity and quality caused by large-scale blackwater in reservoirs with Eucalyptus plantation is currently a point of great interest. Eucalyptus is largely planted in southern China, especially in Nanning, Guangxi, where more than 90% of the drinking water source reservoirs are surrounded by Eucalyptus, and different degrees of blackwater often occur in many reservoirs. Recent research has demonstrated that reservoir sediments play an important role in the migration and transformation of Fe2+, Mn2+, S2-, and dissolved organic carbon (DOC) in the overlying water. It is of great significance to explore the distribution characteristics and migration rules of pollutants in the sediment-water interface to reveal the mechanism of blackwater in reservoirs. Experiments were carried out three times in a typical blackwater reservoir (Tianbao Reservoir) in southern China from July to December 2018. The distribution characteristics and seasonal variations of iron, manganese, sulfide, and organic matter in sediments were analyzed, focusing mainly on the profile distribution and migration direction of Fe2+, Mn2+, S2- and DOC in pore water during blackwater periods. The results showed that:① The content of iron and manganese in sediments of reservoirs with Eucalyptus plantation is high, far exceeding the background value of soil content in China. The content of iron, manganese, and total organic carbon (TOC) in the surface sediments increases simultaneously, mainly caused by the input and settlement of the material (litter, decomposed liquids. and soil particles) in the Eucalyptus forest around the reservoir. ② The concentration of Fe2+(16.99 mg·L-1) and the content of DOC (36.80%) in pore water during the blackwater period are significantly higher than those in Taihu Lake during the black bloom (12.15 mg·L-1, 10.78%). The mean concentrations of Fe2+ and Mn2+ are more than 300 times higher than that of S2-, and the reduction conditions in the sediments are dominated by iron and manganese oxides. ③ The diffusion flux of Fe2+ is 27.4-33.5 mg·(m2·d)-1, which is 32.6, 4.9, and 30.8 times higher than those of Taihu Lake, Aha Reservoir, and Hongfeng Lake, respectively. This implies strong Fe2+ release ability from sediments to the overlying water. As a positive correction exists between Fe2+ and DOC, the complex reaction between Fe2+ and organic matter is one of the most important causes of blackwater in reservoirs with Eucalyptus plantation.

The behaviors of Microcystis aeruginosa and microcystins during the Fe2+/persulfate (PS) preoxidation-coagulation and flocs storage period

The frequent occurrence of toxin-producing cyanobacteria blooms driven by anthropogenic eutrophication has become a major threat to aquaculture ecosystems worldwide. In this study, the behavior of M. aeruginosa cells during flocs storage period of 6 days was first investigated after pre-oxidation and coagulation of Fe2+/PS. Fe2+/PS achieved a superior removal efficiency of 90.7% for OD680 and 90.4% for chl-a. The contents of extracellular MCs in the pre-oxidation and coagulation system were significantly (P < 0.05) lower than those in the control. A significant (P < 0.05) difference in intracellular protein between the control and the coagulated systems was observed. Three-dimensional fluorescence excitation emission matrix (EEM) was employed to investigate the variations in extracellular organic matter (EOM) during flocs storage. The results indicated the presence of four peaks, representing protein-like substances, intermediate dissolved microbial metabolites, fulvic and humic-like compounds in the Fe2+/PS process. And the intensities of four peaks were all decreased in the Fe2+/PS system compared to those in the control. A low level of accumulated residual Fe of 0.28 mg/L was observed without posing potential environmental risk. The results showed that the M. aeruginosa cells were under stressful conditions after 3-d storage due to the decomposition of extracellular polymeric substances (EPSs) and the insufficient supply of nutrients. However, SEM results indicated that no significant alteration in cell morphology was observed. Therefore, with high removal of M. aeruginosa, low MCs concentrations, and trivial cell damage, the Fe2+/PS preoxidation-coagulation was proved to be an environmental-friendly method for cyanobacteria removal without yielding serious secondary pollution. This work will contribute to better understanding and managing the cyanobacteria-laden aquaculture water after pre-oxidation and coagulation.

Variation of effluent organic matter (EfOM) during anaerobic/anoxic/oxic (A2O) wastewater treatment processes

Here, we studied seasonal variation of effluent organic matter (EfOM), based on molecular weight distribution and fluorescent components, during the traditional anaerobic/anoxic/oxic (A2O) wastewater treatment processes. Microbial community structure and effect of temperature on some isolated pure strains were analyzed to explain the related mechanism. Results showed that the anaerobic process played a key role in EfOM removal by removing building blocks, low molecular weight (LMW) neutrals, biopolymers, and protein-related substances (C4 and C5), thus determining the fate of EfOM during the A2O processes. On the other hand, humic substances, LMW neutrals, large molecular-sized hydrophobic humic-like compounds (C3), and aromatic proteins (C4) were generated during the anoxic process in summer and winter. Proteobacteria (Gamma-, Beta-, and Alpha-proteobacteria) and Bacteroidetes constituted over 50% of the sludge community. Temperature was found to be positively correlated with the generation of soluble microbial products (SMP) based on the performance of the mixture of isolated Herbaspirillum sp. (Beta-proteobacteria) and Pseudomonas sp. (Gamma-proteobacteria). Through comprehensive analysis of the co-action of Proteobacteria and temperature, we proposed the Synergetic Effect of Temperature and Proteobacteria as a possible mechanism of the seasonal variation of EfOM. These findings are important for understanding the fate of EfOM during the wastewater treatment processes and therefore be helpful for better EfOM control.

Spatial variation of nutrients and primary productivity in the Rufiji Delta mangroves, Tanzania

Determinations of spatial and temporal variations in organic matter and nutrient dynamics in water and sediments are crucial for understanding changes in aquatic bodies. In this study, we (i) determine the spatial dynamics of dissolved inorganic nutrients, during the transition from the dry to the rainy season, and (ii) provide future productivity predictions for the Rufiji Delta mangroves, Tanzania, based on the input of various nutrients. Water samples were collected from six locations, three times per year between April 2012 and January 2014, and analysed for dissolved nutrients, total organic and inorganic carbon, chlorophyll a, chlorophyll b and total carotenoids. The prediction of future net primary productivity in the Rufiji mangroves was undertaken using the software STELLA. The mean nutrient concentrations were of the order: nitrate > phosphate > ammonium > silica > dissolved organic carbon. The study revealed that high nutrient concentrations occurred in the northern part of the Rufiji Delta as a result of anthropogenic influence in the watershed. Modelling of nutrient inputs into the delta indicated enhanced primary productivity, which is expected to increase the vulnerability of water quality in the near future due to eutrophication.

Spatial and Seasonal Variations of Sedimentary Organic Matter in a Subtropical Bay: Implication for Human Interventions.

Elemental (total organic carbon (TOC) and total nitrogen (TN)) and stable carbon and nitrogen isotope compositions (δ13C and δ15N, respectively) in the surface sediment of Zhanjiang Bay (ZJB) in spring and summer were measured to study the spatial and seasonal changes of organic matter (OM) and assess the human-induced and environment-induced changes in the area. The OM in the surface sediment of ZJB was a mixture of terrestrial and marine sources, and was dominated by marine OM (54.9% ± 15.2%). Compared to the central ZJB, the channel and coastal ZJB areas had higher δ13C and δ15N values, higher TOC and TN concentrations, and lower TOC/TN ratios, indicating higher primary productivity and higher percentages of marine OM in the latter two subregions. Mariculture activities, sewage inputs, and dredging were responsible for these phenomena. Clear seasonal variations in OM were observed in ZJB. The average proportions of terrestrial OM in summer increased by 10.2% in the ZJB channel and 26.0% in the coastal ZJB area compared with those in spring. Heavy rainfall brought a large amount of terrestrial OM into the channel and coastal ZJB areas, leading to the increase of the terrestrial OM fraction in these two subregions in summer. In summary, anthropogenic influences had a significant influence on the spatial and seasonal variations of sedimentary OM in ZJB.