12701. 题目: Enhanced global primary production by biogenic aerosol via diffuse radiation fertilization
期刊: Nature Geoscience
作者: A. Rap, C. E. Scott, C. L. Reddington, L. Mercado, R. J. Ellis, S. Garraway, M. J. Evans, D. J. Beerling, A. R. MacKenzie, C. N. Hewitt, D. V. Spracklen
摘要: Terrestrial vegetation releases large quantities of plant volatiles into the atmosphere that can then oxidize to form secondary organic aerosol. These particles affect plant productivity through the diffuse radiation fertilization effect by altering the balance between direct and diffuse radiation reaching the Earth’s surface. Here, using a suite of models describing relevant coupled components of the Earth system, we quantify the impacts of biogenic secondary organic aerosol on plant photosynthesis through this fertilization effect. We show that this leads to a net primary productivity enhancement of 1.23 Pg C yr−1 (range 0.76–1.61 Pg C yr−1 due to uncertainty in biogenic secondary organic aerosol formation). Notably, this productivity enhancement is twice the mass of biogenic volatile organic compound emissions (and ~30 times larger than the mass of carbon in biogenic secondary organic aerosol) causing it. Hence, our simulations indicate that there is a strong positive ecosystem feedback between biogenic volatile organic compound emissions and plant productivity through plant-canopy light-use efficiency. We estimate a gain of 1.07 in global biogenic volatile organic compound emissions resulting from this feedback.
12702. 题目: The effect of land use in the catchment and meteorological conditions on the riverine transport of dissolved organic carbon into the Puck Lagoon (southern Baltic)
期刊: Environmental Monitoring and Assessment
作者: Dominika Saniewska, Karolina Gębka, Katarzyna Łukawska-Matuszewska, Magdalena Bełdowska, Agnieszka Wochna
摘要: Dissolved organic carbon (DOC) concentration and fluxes from four rivers draining the catchment of the Puck Lagoon in southern Baltic are presented. Water samples from rivers and coastal zone close to the rivers’ mouth were collected from April 2015 to March 2017. DOC was measured using high temperature catalytic oxidation with an NDIR detection. DOC concentration in rivers as well as area specific load discharged to the lagoon reflected variations of land use along their course. Area specific load of DOC discharged by rivers with high proportion of forests, meadows, and pastures in the catchment was significantly higher as compared to rivers with catchment dominated by arable land. However, the main controlling factor of the total discharged loads of DOC was the water flow. The highest loads were observed during the downpour. That was due to the larger volumes of water transported with rivers and the higher concentration of DOC resulting from increased leaching from the catchment area. The obtained results are especially important in the light of climate change in the southern Baltic region. According to the forecasts, we can expect increased precipitation and flooding and consequently increased leaching from the catchment and transport of DOC to the sea via rivers.
12703. 题目: The export flux of particulate organic carbon derived from 210Po / 210Pb disequilibria along the North Atlantic GEOTRACES GA01 (GEOVIDE) transect
作者: Yi Tang, Nolwenn Lemaitre, Maxi Castrillejo, Montserrat Roca-Martí, Pere Masqué, and Gillian Stewart
摘要: The disequilibrium between 210Po activity and 210Pb activity in seawater samples was determined along the GEOTRACES GA01 transect in the North Atlantic during the GEOVIDE cruise (May–June 2014). A steady-state model was used to quantify vertical export of particulate 210Po. The deficits of 210Po in the Iberian Basin and at the Greenland Shelf were strongly affected by vertical advection. Using the export flux of 210Po and the particulate organic carbon (POC) to 210Po ratio on total (>1µm) particles, we determined the POC export fluxes along the transect. Both the magnitude and efficiency of the estimated POC export flux from the surface ocean varied spatially within our study region. Export fluxes of POC ranged from negligible to 10mmolCm−2d−1, with enhanced POC export in the Labrador Sea. The cruise track was characterized by overall low POC export relative to net primary production (export efficiency<1–15%); but relatively high export efficiencies were seen in the basins where diatoms dominated the phytoplankton community. The particularly low export efficiencies in the Iberian Basin, on the other hand, were explained by the dominance of smaller phytoplankton, in particular, coccolithophores. POC fluxes estimated from the 210Po/210Pb and 234Th/238U disequilibria agreed within a factor of 3 along the transect, with higher POC estimates generally derived from 234Th. The differences were attributed to integration timescales and the history of bloom events.
12704. 题目: Floating wetlands: an innovative tool for wastewater treatment
期刊: CLEAN - Soil, Air, Water
作者: Munazzam Jawad Shahid, Muhammad Arslan, Shafaqat Ali, Muhammad Siddique, Muhammad Afzal
摘要: Floating treatment wetland (FTW) is an effective, and sustainable technology for wastewater treatment. It has been widely adopted for treating various kinds of polluted water including agricultural runoff, stormwater, industrial effluents, etc. In FTWs, plants are vegetated on a floating mat while their roots are extended down to the contaminated water acting as biological filters. Nutrients and potentially toxic metal(s)/element(s) are taken up from the wastewater by plants through their roots whereas organic matter is degraded by the microorganisms forming biofilms on the roots and mat surface. Additionally, organic contaminants which are already taken up by the plants are degraded by endophytic bacteria in planta. This article provides an overview of FTWs and its application for wastewater treatment. The key factors which have an impact on the performance of FTWs are also described. Lastly, potential role of combined use of plants and bacteria in FTWs for the maximum remediation of polluted water is emphasized.
12705. 题目: Warming enhances sedimentation and decomposition of organic carbon in shallow macrophyte-dominated systems with zero net effect on carbon burial
期刊: Global Change Biology
作者: Mandy Velthuis, Sarian Kosten, Ralf Aben, Garabet Kazanjian, Sabine Hilt, Edwin T. H. M. Peeters, Ellen van Donk, Elisabeth S. Bakker
摘要: Temperatures have been rising throughout recent decades and are predicted to rise further in the coming century. Global warming affects carbon cycling in freshwater ecosystems, which both emit and bury substantial amounts of carbon on a global scale. Currently, most studies focus on the effect of warming on overall carbon emissions from freshwater ecosystems, while net effects on carbon budgets may strongly depend on burial in sediments. Here, we tested whether year‐round warming increases the production, sedimentation, or decomposition of particulate organic carbon and eventually alters the carbon burial in a typical shallow freshwater system. We performed an indoor experiment in eight mesocosms dominated by the common submerged aquatic plant Myriophyllum spicatum testing two temperature treatments: a temperate seasonal temperature control and a warmed (+4°C) treatment (n = 4). During a full experimental year, the carbon stock in plant biomass, dissolved organic carbon in the water column, sedimented organic matter, and decomposition of plant detritus were measured. Our results showed that year‐round warming nearly doubled the final carbon stock in plant biomass from 6.9 ± 1.1 g C in the control treatment to 12.8 ± 0.6 g C (mean ± SE), mainly due to a prolonged growing season in autumn. DOC concentrations did not differ between the treatments, but organic carbon sedimentation increased by 60% from 96 ± 9.6 to 152 ± 16 g C m−2 year−1 (mean ± SE) from control to warm treatments. Enhanced decomposition of plant detritus in the warm treatment, however, compensated for the increased sedimentation. As a result, net carbon burial was 40 ± 5.7 g C m−2 year−1 in both temperature treatments when fluxes were combined into a carbon budget model. These results indicate that warming can increase the turnover of organic carbon in shallow macrophyte‐dominated systems, while not necessarily affecting net carbon burial on a system scale.
12706. 题目: Chinese cropping systems are a net source of greenhouse gases despite soil carbon sequestration
期刊: Global Change Biology
作者: Bing Gao, Tao Huang, Xiaotang Ju, Baojing Gu, Wei Huang, Lilai Xu, Robert M. Rees, David S. Powlson, Pete Smith, Shenghui Cui
摘要: Soil carbon sequestration is being considered as a potential pathway to mitigate climate change. Cropland soils could provide a sink for carbon that can be modified by farming practices, however, they can also act as a source of greenhouse gases (GHG), including not only nitrous oxide (N2O) and methane (CH4), but also the upstream carbon dioxide (CO2) emissions associated with agronomic management. These latter emissions are also sometimes termed “hidden” or “embedded” CO2. In this paper, we estimated the net GHG balance for Chinese cropping systems by considering the balance of soil carbon sequestration, N2O and CH4 emissions, and the upstream CO2 emissions of agronomic management from a life cycle perspective during 2000–2017. Results showed that although soil organic carbon (SOC) increased by 23.2±8.6 Tg C yr−1, the soil N2O and CH4 emissions plus upstream CO2 emissions arising from agronomic management added 269.5±21.1 Tg C‐eq yr−1 to the atmosphere. These findings demonstrate that Chinese cropping systems are a net source of GHG emissions, and that total GHG emissions are about 12 times larger than carbon uptake by soil sequestration. There were large variations between different cropping systems in the net GHG balance ranging from 328 to 7567 kg C‐eq ha−1 yr−1, but all systems act as a net GHG source to the atmosphere. The main sources of total GHG emissions are nitrogen fertilization (emissions during production and application), power use for irrigation, and soil N2O and CH4 emissions. Optimizing agronomic management practices, especially fertilization, irrigation, plastic mulching, and crop residues to reduce total GHG emissions from the whole chain is urgently required in order to develop a low carbon future for Chinese crop production.
12707. 题目: Comparison of Sorption to Carbon-Based Materials and Nanomaterials Using Inverse Liquid Chromatography
期刊: Environmental Science & Technology
作者: Florian Metzelder, Matin Funck, Thorsten Hüffer, Torsten C. Schmidt
摘要: Sorption studies of carbon-based materials and nanomaterials are typically conducted using batch experiments, but the analysis of weakly sorbing compounds may be challenging. Column chromatography represents a promising complement as higher sorbent to solution ratios can be applied. The sorbent is packed in a column, and sorption data are calculated by relating sorbate retention times to that of a nonretarded tracer. In this study, sorption of heterocyclic organic compounds (pyrazole, pyrrole, furan, and thiophene) by carbon-based materials (activated carbon, biochar, and graphite) and nanomaterials (functionalized carbon nanotubes and graphene platelets) was compared for the first time using column chromatography. D2O was used as nonretarded tracer. Sorption isotherms were nonlinear and described well by the Freundlich model. Sorption differed between the materials regarding determined Freundlich coefficients (Kf) by more than two orders of magnitude for isotherms in a similar concentration range. Normalization of Kf with the surface area of the sorbent significantly reduced but did not remove the differences between the sorbents. Overall, column chromatography represents the opportunity to study sorption of weakly sorbing compounds to diverse carbon-based sorbent materials with a single experimental approach, which is challenging in batch experiments because of the very different sorption properties of some sorbent materials.
12708. 题目: Biodegradation of sulfadiazine in microbial fuel cells: Reaction mechanism, biotoxicity removal and the correlation with reactor microbes
期刊: Journal of Hazardous Materials
作者: Lu Wang, Lexing You, Jiaming Zhang, Tao Yang, Wei Zhang, Zhongxiang Zhang, Pinxing Liu, Song Wu, Feng Zhao, Jun Ma
摘要: Sulfadiazine (SDZ) is a high priority sulfonamide antibiotic and was always detected in environmental samples. This study explored the removal of SDZ in microbial fuel cells (MFCs), in terms of MFC operation, degradation products, reaction mechanism, SDZ biotoxicity removal, and the correlation between microbial community and SDZ removal. SDZ would greatly impact the activity of reactor microbes, and longtime acclimation is required for the biodegradation of SDZ in MFCs. After acclimation, 10 mg/L of SDZ could be removed within 48 h. Liquid chromatographic-mass spectroscopic analysis showed that SDZ could be degraded into 2-aminopyrimidine, 2-amino-4-hydroxypyrimidine and benzenesulfinic acid. Compared with published SDZ biodegradation mechanism, we found that the sulfanilamide part (p-Anilinesulfonic acid) of SDZ would be degraded into benzenesulfinic acid in the system. The effects of background constituents on SDZ biodegradation were explored, and co-existed humic acid (HA) and fulvic acid (FA) could accelerate the removal of SDZ in MFCs. After analyzing the reactor microbial community and the removal of SDZ at different operation cycles, it was found that the relative abundance of Methanocorpusculum, Mycobacterium, Clostridium, Thiobacillus, Enterobacter, Pseudomonas, and Stenotrophomonas was highly correlated with the removal of SDZ throughout the experiment.
12709. 题目: Management versus site effects on the abundance of nitrifiers and denitrifiers in European mountain grasslands
期刊: Science of The Total Environment
作者: Ute Szukics, Karl Grigulis, Nicolas Legay, Eva-Maria Kastl, Catherine Baxendale, Richard D. Bardgett, Jean-Christophe Clément, Sandra Lavorel, Michael Schloter, Michael Bahn
摘要: It is well established that the abundances of nitrogen (N) transforming microbes are strongly influenced by land-use intensity in lowland grasslands. However, their responses to management change in less productive and less fertilized mountain grasslands are largely unknown. We studied eight mountain grasslands, positioned along gradients of management intensity in Austria, the UK, and France, which differed in their historical management trajectories. We measured the abundance of ammonia-oxidizing bacteria (AOB) and archaea (AOA) as well as nitrite-reducing bacteria using specific marker genes. We found that management affected the abundance of these microbial groups along each transect, though the specific responses differed between sites, due to different management histories and resulting variations in environmental parameters. In Austria, cessation of management caused an increase in nirK and nirS gene abundances. In the UK, intensification of grassland management led to 10-fold increases in the abundances of AOA and AOB and doubling of nirK gene abundance. In France, ploughing of previously mown grassland caused a 20-fold increase in AOA abundance. Across sites the abundance of AOB was most strongly related to soil NO3−-N availability, and AOA were favored by higher soil pH. Among the nitrite reducers, nirS abundance correlated most strongly with N parameters, such as soil NO3−-N, microbial N, leachate NH4+-N, while the abundance of nirK-denitrifiers was affected by soil total N, organic matter (SOM) and water content. We conclude that alteration of soil environmental conditions is the dominant mechanism by which land management practices influence the abundance of each group of ammonia oxidizers and nitrite reducers.
12710. 题目: Comparison of different detoxification pilot plants for the treatment of industrial wastewater by solar photo-Fenton: Are raceway pond reactors a feasible option?
期刊: Science of The Total Environment
作者: A. Cabrera-Reina, S. Miralles-Cuevas, G. Rivas, J.A. Sánchez Pérez
摘要: This paper represents a first approach in the study of photoreactor selection to treat industrial wastewater using solar photo-Fenton. In this context, simulated textile industry effluent containing a mixture of four dyes at different initial dissolved organic carbon (DOC) concentrations (45, 90, 180 and 270 mg/L) was treated by using three different solar reactor geometries: (i) tubular (5 cm diameter) provided with compound parabolic collector (ii) tubular (5 cm diameter) provided with flat collector and (iii) open channels forming raceway ponds with two liquid depths (5 and 15 cm). For comparison purposes, mineralisation percentages over 75% and chronic toxicity reduction were set as treatment goals. Regardless of the initial DOC concentration, negligible differences in terms of treatment time and hydrogen peroxide consumptions were found between the flat collector and compound parabolic collector photoreactors. Conversely, the treatment in the raceway pond reactors always resulted in higher values. In spite of this, when the photoreactors were compared in terms of treatment capacity (mg of DOC removed/m2 min) the raceway pond reactor at 15 cm of liquid depth presented the best results, with values as much as two or three times higher than those of the tubular reactors, except for the wastewater with 270 mg of DOC/L for which the raceway pond reactor at 5 cm liquid depth became the best option. When the treatment capacity is modified to include the photoreactor investment (mg of DOC removed/€ m2) the differences between the raceway pond reactor at both liquid depths and the photoreactors with solar collectors increased by as much as two orders of magnitude, which demonstrates the potential application of the former for the treatment of industrial wastewater by solar photo-Fenton.
12711. 题目: Effects of sediment components and TiO 2 nanoparticles on perfluorooctane sulfonate adsorption properties
期刊: Journal of Soils and Sediments
作者: Kun Li, Peifang Wang, Jin Qian, Chao Wang, Linghang Xing, Jingjing Liu, Xin Tian, Bianhe Lu, Wenyi Tang
摘要: Purpose: Here, the roles of sediment components in perfluorooctane sulfonate (PFOS) adsorption onto aquatic sediments and relevant adsorption mechanisms were investigated in terms of adsorption isotherms and influences of TiO2 nanoparticles (NPs) contamination. Materials and methods: Due to the complexity of the sediments, instead of randomly selecting different component sediments, the selective dissolution method was used to better explore the effects of sediment compositions, such as sediment organic matter (SOM) and ferric oxides (dithionite–citrate–bicarbonate [DCB] Fe), and TiO2 NPs pollution on PFOS adsorption. Mathematical equations (Freundlich, Langmuir, and Temkin) were used to describe the adsorption behavior of PFOS on different sediments and adsorption mechanisms of multiple pollutant interactions. Moreover, the characterization methods of zeta potential, nitrogen (N2) adsorption–desorption, and scanning electron microscopy (SEM) analysis, as well as Fourier transform infrared (FT-IR) spectroscopy, explained effects of the sediment components and TiO2 NPs on PFOS adsorption properties in view of physicochemical theories. Results and discussion: The adsorption isotherms of PFOS on six tested sediments were all nonlinear (Freundlich model, R2 = 0.992~1.000). The Freundlich sorption affinities (KF) of PFOS on S (original sediments), S1 (sediment organic matter (SOM)-removed S), and S2 (ferric oxides (DCB Fe)-removed S1) were 0.232, 0.179, and 0.120, respectively. Both SOM and DCB Fe influenced the physicochemical properties of the sediments, e.g., zeta potential, specific surface area, and permanent negative charge. The addition of TiO2 NPs increased the KF of PFOS for S, S1, and S2 by approximately 9.9%, 14.5%, and 26.7%, respectively, by increasing the zeta potential and specific surface area (SBET, Sext, and Smicro) and by changing the water and oil properties of the three sediments. However, the addition of TiO2 NPs decreased the linearity of the sorption isotherm (1/n). FT-IR spectroscopy showed that hydrophobicity, ion exchange, surface complexation, and hydrogen bonding interactions (non-fingerprint region) could all play a role in PFOS sorption onto tested sediments. However, the hypothesis of hydrogen bonding to promote PFOS adsorption on sediment layer silicates (fingerprint region) should be studied further. Conclusions: The content of both SOM and DCB Fe affected the physicochemical properties of sediment. Both SOM and DCB Fe showed a positive relationship with sorption of PFOS on sediment. The addition of TiO2 NPs increased PFOS sorption by altering the sediment surface properties. Hydrophobic interactions certainly impelled and ligand and ion exchange and hydrogen bonding (non-fingerprint region) could promote PFOS sorption on the sediments.
12712. 题目: Chronic toxicity of an environmentally relevant and equitoxic ratio of five metals to two Antarctic marine microalgae shows complex mixture interactivity
期刊: Environmental Pollution
作者: Darren J. Koppel, Merrin S. Adams, Catherine K. King, Dianne F. Jolley
摘要: Metal contaminants are rarely present in the environment individually, yet environmental quality guidelines are derived from single-metal toxicity data. Few metal mixture studies have investigated more than binary mixtures and many are at unrealistically high effect concentrations to freshwater organisms. This study investigates the toxicity of five metals (Cd, Cu, Ni, Pb, and Zn) to the Antarctic marine microalgae Phaeocystis antarctica and Cryothecomonas armigera. Two mixtures were tested: (i) an equitoxic mixture of contaminants present at their single-metal EC10 concentrations, and (ii) an environmental mixture based on the ratio metal concentrations in a contaminated Antarctic marine bay.Observed toxicity, as chronic population growth rate inhibition, was compared to Independent Action (IA) and Concentration Addition (CA) predictions parameterised to use EC10 values. This allowed for the inclusion of metals with low toxicities. The biomarkers chlorophyll a fluorescence, cell size and complexity, and intracellular lipid concentrations were assessed to investigate possible mechanisms behind metal-mixture interactions.Both microalgae had similar responses to the equitoxic mixture: non-interactive by IA and antagonistic by CA. Toxicity from the environmental mixture was antagonistic by IA to P. antarctica; however, to C. armigera it was concentration-dependent with antagonism at low toxicities and synergism at high toxicities by both IA and CA. Differences in dissolved organic carbon production and detoxification mechanisms may be responsible for these responses and warrants further investigation.This study shows that mixture toxicity interactions can be ratio, species, and concentration dependent. The responses of the microalgae to different mixture ratios highlight the need to assess toxicity at environmentally realistic metal ratios. Parameterising IA and CA reference models to use EC10s allowed for the inclusion of metals at low effect concentrations, which may otherwise be ignored. Reference mixture models are generally suitable for predicting chronic toxicity of metals to these marine microalgae at environmentally realistic ratios and concentrations.
12713. 题目: Volatile fatty acids production from food wastes for biorefinery platforms: A review
期刊: Journal of Environmental Management
作者: Giuseppe Strazzera, Federico Battista, Natalia Herrero Garcia, Nicola Frison, David Bolzonella
摘要: Volatile fatty acids (VFAs) are a class of largely used compounds in the chemical industry, serving as starting molecules for bioenergy production and for the synthesis of a variety of products, such as biopolymers, reduced chemicals and derivatives. Because of the huge amounts of food waste generated from household and processing industry, 47 and 17 million tons per year respectively only in the EU-28 Countries, food wastes can be the right candidate for volatile fatty acids production. This review investigates all the major topics involved in the optimization of VFAs production from food wastes. Regarding the best operative conditions for the anaerobic fermenter controlled pH in the neutral range (6.0–7.0), short HRT (lower than 10 days), thermophilic temperatures and an organic loading rate of about 10 kgVS/m3d, allowed for an increase in the VFAs concentration between 10 and 25%. It was also found that additions of mineral acids, from 0.5 to 3.0%, and thermal pretreatment in the range 140–170 °C increase the organic matter solubilisation. Applications of VFAs considered in this study were biofuels and bioplastics production as well as nutrients removal in biological wastewater treatment processes.
12714. 题目: Clay amount and distribution influence organic carbon content in sand with subsoil clay addition
期刊: Soil and Tillage Research
作者: Amanda Schapel, Petra Marschner, Jock Churchman
摘要: Sandy soils cover large proportions of Australia’s cereal-cropping region and are wide-spread globally. Sandy soils often have low organic C (OC) content due to limited plant growth and rapid decomposition because of low clay concentration. The addition of subsoil clay to sandy soil has the potential to increase OC storage. This study aimed to (i) compare OC stock in a range of clay-amended and unamended sandy soils under cereal cropping and (ii) identify factors that influence OC stock to develop best practices to increase OC storage in clay-amended sandy soils. The study was carried out on four agricultural properties in South Australia and assessed soil OC content, clay content and select physical and chemical properties of clay-amended treatments compared to unamended sands. Clay-amendment treatments differed in the method of clay amendment (clay spread and delved), depth of incorporation (shallow and deep) and amount of subsoil clay added to the surface 30 cm of sand. For each site and treatment, ten soil cores to 50 cm depth were collected within a 25 m grid. There was a positive correlation between OC and clay stock, but it only explained 46% of the variation in OC stock. This indicated that other factors influenced OC stock in clay-amended treatments. Even vertical distribution of clay within the surface 30 cm was a key factor to increase OC storage in clay-amended soils. Subsoil clay properties and the amount added to the surface 30 cm, as well as depth to undisturbed subsoil also influenced OC stock.
12715. 题目: Fabrication of GO/CDots/BiOI nanocomposites with enhanced photocatalytic 4-chlorophenol degradation and mechanism insight
期刊: Separation and Purification Technology
作者: Songying Qu, Yuhan Xiong, Jun Zhang
摘要: Non-metallic graphene oxide (GO) and carbon nanodots (CDots) co-doped BiOI ternary system (GO/CDots/BiOI) was successfully synthesized via a simple one-step solvothermal process. The compositional characterization, optical and electrical properties of photocatalysts were investigated in detail. The prepared ternary photocatalysts possessed the excellent visible-light driven photocatalytic 4-chlorophenol (4-CP) degradation. Additionally, the 4-CP removal efficiencies decreased in the order of GO/CDots/BiOI (98.2%) > CDots/BiOI (89.9%) > GO/BiOI (78.5%) > pristine BiOI (41.7%) in 3 h under visible light irradiation. The dissolved organic carbon (DOC) removal and the dechlorination efficiency by the GO/CDots/BiOI were 66.3% and 85.2%, respectively, much higher than pristine BiOI. The co-existence of GO and CDots on the BiOI greatly promoted visible light harvesting and utilizing ability and inhibited the recombination of photogenerated electron/hole pairs. The synergistic effect between GO, CDots and BiOI was expounded, and the photocatalytic reaction mechanism was proposed in detail via the band structure analysis and free radical trapping experiments.
12716. 题目: Warming enhances sedimentation and decomposition of organic carbon in shallow macrophyte‐dominated systems with zero net effect on carbon burial
期刊: Global Change Biology
作者: Mandy Velthuis, Sarian Kosten, Ralf Aben, Garabet Kazanjian, Sabine Hilt, Edwin T. H. M. Peeters, Ellen van Donk, Elisabeth S. Bakker
摘要: Temperatures have been rising throughout recent decades and are predicted to rise further in the coming century. Global warming affects carbon cycling in freshwater ecosystems, which both emit and bury substantial amounts of carbon on a global scale. Currently, most studies focus on the effect of warming on overall carbon emissions from freshwater ecosystems, while net effects on carbon budgets may strongly depend on burial in sediments. Here, we tested whether year‐round warming increases the production, sedimentation, or decomposition of particulate organic carbon and eventually alters the carbon burial in a typical shallow freshwater system. We performed an indoor experiment in eight mesocosms dominated by the common submerged aquatic plant Myriophyllum spicatum testing two temperature treatments: a temperate seasonal temperature control and a warmed (+4°C) treatment (n = 4). During a full experimental year, the carbon stock in plant biomass, dissolved organic carbon in the water column, sedimented organic matter, and decomposition of plant detritus were measured. Our results showed that year‐round warming nearly doubled the final carbon stock in plant biomass from 6.9 ± 1.1 g C in the control treatment to 12.8 ± 0.6 g C (mean ± SE), mainly due to a prolonged growing season in autumn. DOC concentrations did not differ between the treatments, but organic carbon sedimentation increased by 60% from 96 ± 9.6 to 152 ± 16 g C m−2 yaer−1 (mean ± SE) from control to warm treatments. Enhanced decomposition of plant detritus in the warm treatment, however, compensated for the increased sedimentation. As a result, net carbon burial was 40 ± 5.7 g C m−2 year−1 in both temperature treatments when fluxes were combined into a carbon budget model. These results indicate that warming can increase the turnover of organic carbon in shallow macrophyte‐dominated systems, while not necessarily affecting net carbon burial on a system scale.
12717. 题目: The prediction of mercury bioavailability for common carp (Cyprinus carpio L.) using the DGT technique in the presence of chloride ions and humic acid
作者: Pavlína Pelcová, Petra Vičarová, Hana Dočekalová, Eva Poštulková, Radovan Kopp, Jan Mareš, Vendula Smolíková
摘要: The ability of the DGT technique to predict Hg2+ bioavailability for input tissues (skin, gills, and scales) of common carp in the presence of chloride ions and humic acid (HA) was evaluated. The mercury accumulation by the DGT units and input tissues of carp decreased with an increasing concentration of chloride ions (29–180 mg L−1) and HA (0–5 mg L−1). In the presence of chloride ions and HA, statistically significant correlations (Pearson's correlation coefficients 0.731–0.954) were determined between the rate of mercury accumulation by input tissues of carp and the rate of mercury accumulation by the DGT units. The laboratory experiments suggest the possibility of using the DGT technique for predicting the mercury bioaccumulation in natural aquatic ecosystems instead of commonly used input tissues of fish.
12718. 题目: Relationship between home-field advantage of litter decomposition and priming of soil organic matter
期刊: Soil Biology and Biochemistry
作者: D.P. Di Lonardo, M. Manrubia, W. De Boer, H. Zweers, G.F. Veen, A. Van der Wal
摘要: Home field advantage (HFA; acceleration of plant litter decomposition in soils that receive their indigenous litter) and priming effects (PE; short-term changes in the turnover of soil organic matter caused by the addition of fresh organic carbon) are two aspects of decomposition processes that are driven by the composition and functioning of soil decomposer communities. Physicochemical similarity between added organic compounds and soil organic matter fractions has been indicated as an important steering factor of PE. It is unknown whether PE, like litter decomposition, experience HFA, i.e., whether PE are higher than expected in soils receiving their own litter due to specialization of the decomposer community. Here we studied both HFA and PE by measuring litter- and SOM-derived carbon (C) fluxes after the addition of fresh plant litter. We reciprocally incubated three 13C labelled litter types (maize, bent and beech) in soils from ecosystems where these litters are abundantly produced (e.g., arable sites, grasslands and forests), with and without the addition of mineral nitrogen (N). Generally, respiration of both litter-derived and SOM-derived C were lowest when beech litter was added, and were lower in forest soils than in arable or grassland soils. N addition generally slightly increased the respiration of litter-derived C, but had no effect on SOM-derived C. All litter types induced a positive PE in all soils. HFA effects were not significantly different from zero, but were significantly higher in grasslands than in maize fields amended with nitrogen. We found a positive relationship between litter and priming HFA, indicating that the rates of both litter decomposition and PE may be affected in the same manner by home combinations of plant and litter versus away combinations. This positive relationship disappeared when N was added. Our results provide a first indication that the extent to which indigenous soil microbes are specialized to breakdown home litter, not only accelerates or decelerates the decomposition of litter, but affects the breakdown of SOM in the same way. This could imply that a specialized litter decomposer community driving HFA can further accelerate soil C mineralization via enhanced induction of PE. Therefore, the impact of specialized decomposer communities on the dynamics of soil C pools may be bigger than expected from HFA of litter decomposition alone.
12719. 题目: A review of landfill leachate induced ultraviolet quenching substances: Sources, characteristics, and treatment
期刊: Water Research
作者: Syeed Md Iskander, Renzun Zhao, Ankit Pathak, Abhinav Gupta, Amy Pruden, John T. Novak, Zhen He
摘要: Landfill leachate contains extremely diverse mixtures of pollutants and thus requires appropriate treatment before discharge. Co-treatment of landfill leachate with sewage in wastewater treatment plants is a common approach because of low cost and convenience. However, some recalcitrant organic compounds in leachate can escape biological treatment processes, lower the UV transmittance of waste streams due to their UV-quenching properties, and interfere with the associated disinfection efficacy. Thus, the leachate UV quenching substances (UVQS) must be removed or reduced to a level that UV disinfection is not strongly affected. UVQS consist of three major fractions, humic acids, fulvic acids and hydrophilics, each of which has distinct characteristics and behaviors during treatment. The purpose of this review is to provide a synthesis of the state of the science regarding UVQS and possible treatment approaches. In general, chemical, electrochemical, and physical treatments are more effective than biological treatments, but also costlier. Integration of multiple treatment methods to target the removal of different fractions of UVQS can aid in optimizing treatment. The importance of UVQS effects on wastewater treatment should be better recognized and understood with implemented regulations and improved research and treatment practice.
12720. 题目: Contrasting fates of petrogenic and biospheric carbon in the South China Sea
期刊: Geophysical Research Letters
作者: T. M. Blattmann, Y. Zhang, Y. Zhao, K. Wen, S. Lin, J. Li, L. Wacker, N. Haghipour, M. Plötze, Z. Liu, T. I. Eglinton
摘要: A synthesis of published and newly acquired stable and radiocarbon isotope data fromsoil, river, and marine particulate organic carbon (OC) from the South China Sea drainageand sedimentary basin reveals that OC derived from bedrock‐erosion (petrogenic OC)and marine productivity comprise the major contributors to bulk OC in particulatematter reaching abyssal depths, while soil‐derived OC appears negligible. Aluminum‐radiocarbonrelationships of sediments suggest that soil OC initially associated with detritalterrestrial minerals is lost and replaced by marine OC during transport beyond thecontinental shelf. We estimate that petrogenic OC sinking to a ~30,000 km2 region of the deep northeastern South China Sea accounts for 0.6% of global petrogenic OC burial. The basin‐wide OC isotope patterns coupled with sediment trap observationshighlight both the spatial variability of OC components as they propagate from sourceto sedimentary sink, and the significance of petrogenic OC to deep ocean sediments.