Source profiles of particulate organic matters emitted from cereal straw burnings

Cereal straw is one of the most abundant biomass burned in China but its contribution to fine particulates is not adequately understood. In this study, three main kinds of cereal straws were collected from five grain producing areas in China. Fine particulate matters （PMzs） from the cereal straws subjected to control burnings, both under smoldering and flaming status, were sampled by using a custom made dilution chamber and sampling system in the laboratory. Element carbon （EC） and organic carbon （OC） was analyzed. 141 compounds of organic matters were measured by gas chromatography-mass spectrum （GC-MS）. Source profiles of particulate organic matters emitted from cereal straw burnings were obtained. The results indicated that organic matters contribute a large fraction in fine particulate matters. Levoglucosan had the highest contributions with averagely 4.5% in mass of fine particulates and can be considered as the tracer of biomass burnings. Methyloxylated phenols from lignin degradation also had high concentrations in PM2.5, and contained approximately equal amounts of guaiacyl and syringyl compounds. 13-Sitostrol also made up relatively a large fraction of PMz5 compared with the other sterols （0.18%-0.63% of the total fine particle mass）. Normal alkanes, PAHs, fatty acids, as well as normal alkanols had relatively lower concentrations compared with the compounds mentioned above. Carbon preference index （CPI） of normal alkanes and alkanoic acids showed characteristics of biogenic fuel burnings. Burning status significantly influenced the formations of EC and PAHs. The differences between the emission profiles of straw and wood combustions were displayed by the fingerprint compounds, which may be used to identify the contributions between wood and straw burnings in source apportionment researches.

Sources of particulate organic matter in the Chukchi and Siberian shelves: clues from carbon and nitrogen isotopes

The stable isotopic composition(δ13C andδ15N)and carbon/nitrogen ratio(C/N)of particulate organic matter(POM)in the Chukchi and East Siberian shelves from July to September,2016 were measured to evaluate the spatial variability and origin of POM.Theδ13CPOC values were in the range of−29.5‰to−17.5‰with an average of−25.9‰±2.0‰,and theδ15NPN values ranged from 3.9‰to 13.1‰with an average of 8.0‰±1.6‰.The C/N ratios in the East Siberian shelf were generally higher than those in the Chukchi shelf,while theδ13C andδ15N values were just the opposite.Abnormally low C/N ratios(<4),lowδ13CPOC(almost−28‰)and highδ15NPN(>10‰)values were observed in the Wrangel Island polynya,which was attributed to the early bloom of small phytoplankton.The contributions of terrestrial POM,bloom-produced POM and non-bloom marine POM were estimated using a three end-member mixing model.The spatial distribution of terrestrial POM showed a high fraction in the East Siberian shelf and decreased eastward,indicating the influence of Russian rivers.The distribution of non-bloom marine POM showed a high fraction in the Chukchi shelf with the highest fraction occurring in the Bering Strait and decreased westward,suggesting the stimulation of biological production by the Pacific inflow in the Chukchi shelf.The fractions of bloom-produced POM were highest in the winter polynya and gradually decreased toward the periphery.A negative relationship between the bloom-produced POM and the sea ice meltwater inventory was observed,indicating that the net sea ice loss promotes early bloom in the polynya.Given the high fraction of bloom-produced POM,the early bloom of phytoplankton in the polynyas may play an important role on marine production and POM export in the Arctic shelves.

Carbon and nitrogen isotopic composition of particulate organic matter and its biogeochemical implication in the Bering Sea

Stable carbon and nitrogen isotopic composition of particulate organic matter （POM） were measured for samples collected from the Bering Sea in 2010 summer. Particulate organic carbon （POC） and particulate nitrogen （PN） showed high concentrations in the shelf and slope regions and decreased with depth in the slope and basin, indicating that biological processes play an important role on POM distribution. The low C/N ratio and heavy isotopic composition of POM, compared to those from the Alaska River, suggested a predominant contribution of marine biogenic organic matter in the Bering Sea. The fact thatδ^13Candδ^15Ngenerally increased with depth in the Bering Sea basin demonstrated that organic components with light carbon or nitrogen were decomposed preferentially during their transport to deep water. However, the highδ^13Candδ^15Nobserved in shelf bottom water were mostly resulted from sediment resuspension.

THE DEGRADABILITY OF PARTICULATE ORGANIC MATTER IN THE GIRONDE ESTUARY, FRANCE

The degradability of particulate organic matter(POM)in the Gironde Estuary(France)was measuredusing the incubation technique.The influence of sample treatment and incubation conditions on the re-sults was evaluated.A mathematical model was successfully used to describe the various degradationcurves.Results showed that the upstream POM had very high degradability;the central estuaryPOM had low degradability;and that the mouth POM degradability was between that of central POM(low degradability)and marine POM(high degradability).

Modeling of Deposition Process of Particulate Organic Matter (POM) with Sand on Vegetated Area in a River

The transport and deposition of particulate organic matter (POM) in river streams has recently received much attention as one of important ecological processes in rivers. We focused on interacted behaviors of sand particles in bed load and POM in vegetated area on sand bars. The purpose of this study is to clarify the characteristics of deposition of POM with bed load on sandbars with the riparian vegetation. A basic experiment on POM transport and deposition with vegetation is conducted in a laboratory flume. It demonstrates that several issues still remain to be future investigated. In particular, the shear due to the bed roughness in the vegetated area and the transport and deposition process of sand particles and POM are required to be described by the proper modeling which will be introduced into a simulation model of various fluvial processes. The main results of this study are that ripples are formed by bed load in riparian vegetation and POM deposition is promoted by ripple behavior. Based on these results, the POM deposition with ripples in vegetated area is described by a conceptual model which will affect various aspects in ecosystem management based on fluvial processes.

VARIATIONS OF THE SUSPENDED MATTERAMD THE PARTICULATE ORGANIC CARBONIN THE ENTRY OF THE GIRONDE ESTUARY, FRANCE

The effects of using different types of glass fiber filters (GF/F, GF/C) and of sample treatments were evaluated. Studies on the variation of suspended matter (SM) and particulate organic carbon (POC) showed that:1) the transversal and day to night variations are important and must be taken into account in order to get a correct river flux; 2) no regular seasonal variations of SM and POC were observed, as they are controlled essentially by the climatological, hydrologic, physiochernical, biological, and geological conditions of the drainage area.

Distribution and Sources of Particulate Organic Matter in the Northern South China Sea: Implications of Human Activity

In order to understand origin and fate of particulate organic matter,the isotopic composition(δ^(13)C andδ^(15)N),total or-ganic carbon content,total nitrogen content,and C/N ratios were measured for suspended particulate organic matter(POM)collected from the northern South China Sea(NSCS)during summer.Our study revealed thatδ^(13)C generally decreased from land to sea,and elevatedδ^(13)C occurred at the nearshore stations,suggesting that POC was mainly contributed from the eutrophic level and microbial activity.Moreover,the distribution ofδ^(15)N values were complicated,and heterotrophic modification was responsible for higherδ^(15)N in the nearshore stations.These distribution patterns ofδ^(13)C andδ^(15)N in the nearshore stations may be associated with the intensifi-cation of human activity in the coast.Based on the Stable Isotope Analysis in R model,65%of POM was contributed by marine or-ganic matter in the NSCS,20%by terrestrial inputs,and 15%by freshwater algae.

Sources and implications of particulate organic matter from a small tropical river——Zuari River, India

Transitional ecosystems,estuaries and the coastal seas,are distinctively affected by natural and anthropogenic factors.Organic matter(OM)originating from terrestrial sources is exported by rivers and forms a key component of the global biogeochemical cycles.Most previous studies focused on the bulk biochemical and anthropogenic aspects affecting these ecosystems.In the present study,we examined the sources and fate of OM entrained within suspended particulate matter(SPM)of the Zuari River and its estuary,west coast of India.Besides using amino acid(AA)enantiomers(L-and D-forms)as biomarkers,other bulk biochemical parameters viz.particulate organic carbon(POC),δ13C,particulate nitrogen(PN),δ15N and chlorophyll a were analyzed.Surprisingly no significant temporal variations were observed in the parameters analyzed;nonetheless,salinity,POC,δ13C,PN,δ15N,glutamic acid,serine,alanine,tyrosine,leucine and D-aspartic acid exhibited significant spatial variability suggesting source differentiation.The POC content displayed weak temporal variability with low values observed during the post-monsoon season attributed to inputs from mixed sources.Estuarine samples were less depleted than the riverine samples suggesting contributions from marine plankton in addition to contributions from river plankton and terrestrial C3 plants detritus.Labile OM was observed during the monsoon and post-monsoon seasons in the estuarine region.More degraded OM was noticed during the pre-monsoon season.Principal component analysis was used to ascertain the sources and factors influencing OM.Principally five factors were extracted explaining 84.52%of the total variance.The first component accounted for 27.10%of the variance suggesting the dominance of tidal influence whereas,the second component accounted for heterotrophic bacteria and their remnants associated with the particulate matter,contributing primarily to the AA pool.Based on this study we ascertained the role of the estuarine turbidity maximum(ETM)controlling the sources of POM and its implications to small tropical rivers.Thus,changes in temporal and regional settings are more likely to affect the natural biogeochemical cycles of small tropical rivers.

Effect of Cultivation on Soil Organic Matter and Aggregate Stability

Agricultural sustainability relates directly to maintaining or enhancing soil quality. Soil quality studies in Canada during the 1980 s showed that loss of soil organic matter (SOM) and soil aggregate stability was standard features of non-sustainable land management in agroecosystems. In this study total soil organic carbon (SOC), particulate organic matter (POM), POM-C as a percentage of total SOC, and aggregate stability were determined for three cultivated fields and three adjacent grassland fields to a…

Copper and Zinc Enrichment in Different Size Fractions of Organic Matter from Polluted Soils

Bioavailability of heavy metals in soil organic matter depends on itscomponents. Characterization of heavy metal distributions in different fractions of soil organicmatter is needed for better understanding of the fate of heavy metals. This study investigated theaccumulation and partitioning of copper and zinc among different size particulate organic matter(POM) fractions in polluted soils from a former iron ore processing site in western Shaoxing County,Zhejiang Province. Physical fractionations were carried out to separate soil primary particlesaccording to their size and density. Copper and Zn had a heterogeneous distribution among soilparticle fractions. Copper and Zn were significantly (p < 0.05) enriched in the POM fractions. >0.05 mm POM and < 0.05 mm fine soil fractions were mainly responsible for Cu and Zn retention insoils. The POM fraction contained up to 1 322 mg Cu kg^(-1) and 1115 mg Zn kg^(-1) and the fine soilfraction contained up to 422 mg Cu kg^(-1) and 537 mg Zn kg^(-1). The total POM fraction wasresponsible for 15.8%-41.2% and 12.2%-31.7% of the total amount of Cu and Zn, respectively, in thepolluted soils. The percentages of Cu and Zn associated with organic matter in < 0.05 mm fine soilfractions for the polluted soils ranged from 14.1% to 24.5%, and 5.4% to 15.8%, respectively.Accumulation of soil organic matter could increase enrichment of Cu (or Zn) in the POM fractions.Also, Cu provided a greater enrichment in the POM fractions than Zn.

Soil Aggregates, Organic Matter, and Labile C and N Fractions after 37 Years of N, P and K Applications to an Irrigated Subtropical Soil under Maize-Wheat Rotation

Abstract： Physical, chemical and biological soil properties in surface （0-5 cm） and subsurface soil （5-15 cm） were determined in a field experiment conducted with seven treatments consisted of different combinations of fertilizer N （0, 100 and 200 kg N ha^-1）, P （0, 22 and 44 kg P2O5 ha^-1） and K （0, 41 and 82 kg K2O ha^-1） applied both to summer-grown maize （Zea mays L.） and winter-grown wheat （Triticum aestivum L.） crops continuously for 37 years under irrigated subtropical conditions. Application of N, P and K significantly increased water stable aggregates and had profound effects in increasing the mean weight diameter as well as the formation of macro-aggregates, which were highest in both surface （81%） and subsurface （74%） soil layers with application of 100 kg N ＋ 22 kg P2O5 ＋ 41 kg K2O ha^-1 （N100P22K41）. The N100P22K41 treatment also enhanced total organic C （TOC） from 4.4 g kg^-1 in no-NPK control to 4.8 g kg^-1in surface layer and from 3.3 to 4.1 g kg1 in subsurface layer leading to the 20% higher TOC stocks in 0-15 cm soil. The labile C and N fractions such as water soluble C, particulate and light fraction organic matter, potentially mineralizable N and microbial biomass were also highest under the optimized balanced application of N100P22K41. Relatively higher increase in all labile fractions of C and N as proportion of TOC and total N, respectively suggested that these are potential indicators to reflect changes in management practices long before changes in TOC and TN are detectable. These results demonstrated that optimized balanced application of N, P and K is crucial for improving soil health ensuring long-term sustainability of farming systems in semiarid subtropical soils.

Control of different occurrence types of organic matter on hydrocarbon generation in mudstones

Organic matter(OM) is preserved as different occurrences in mudstones, which can affect the hydrocarbon generation process. However, little research has focused on hydrocarbon generation as a function of different occurrences of OM. This study collected a suite of mudstones in the Dongying Sag, Bohai Bay Basin, and conducted Rock-Eval Ⅵ pyrolysis after Soxhlet extraction and Na_(2)S_(2)O_(8) oxidation, aiming to quantify the OM with different occurrences and figure out the contributions of each occurrence of OM to the hydrocarbon generation. There are three types of occurrences of OM: soluble organic matter(SOM),mineral-bound organic matter(MOM), and particulate organic matter(POM). MOM is the most abundant among the three occurrence types of OM. SOM and MOM are the main hydrocarbon precursors, and their hydrocarbon contributions alternate with different kerogen types and layers. Additionally, MOMcontributed hydrocarbons are numerous at shallow depths;SOM-contributed hydrocarbons mainly occur at deep depths;and POM-contributed hydrocarbons change little with depth. These results demonstrate that MOM should be the main hydrocarbon precursor in shallow formations and that SOM is the main hydrocarbon contributor at deep depths.

Long-Term Effect of No-Tillage on Soil Organic Carbon Fractions in a Continuous Maize Cropping System of Northeast China

Increasing evidence has shown that conservation tillage is an effective agricultural practice to increase carbon （C） sequestration in soils. In order to understand the mechanisms underlying the responses of soil organic carbon （SOC） to tillage regimes, physical fractionation techniques were employed to evaluate the effect of long-term no-tillage （NT） on soil aggregation and SOC fractions. Results showed that NT increased the concentration of total SOC by 18.1% compared with conventional tillage （CT） under a long-term maize （Zea mays L.） cropping system in Northeast China. The proportion of soil large macroaggregates （〉 2 000 μm） was higher in NT than that in CT, while small macroaggregates （250-2 000μm） showed an opposite trend. Therefore, the total proportion of macroaggregates （〉 2 000 and 250-2 000μm） was not affected by tillage management. However, C concentrations of macroaggregates on a whole soil basis were higher under NT relative to CT, indicating that both the amount of aggregation and aggregate turnover affected C stabilization. Carbon concentrations of intra-aggregate particulate organic matter associated with microaggregates （iPOM-m） and microaggregates occluded within macroaggregates （iPOM-mM） in NT were 1.6 and 1.8 times greater than those in CT, respectively. Carbon proportions of iPOM-n and iPOM-mM in the total SOC increased from 5.4% and 6.3% in CT to 7.2% and 9.7% in NT, respectively. Furthermore, the difference in the microaggregate protected C （i. e., iPOM-m and iPOM-mM） between NT and CT could explain 45.4% of the difference in the whole SOC. The above results indicate that NT stimulates C accumulation within microaggregates which then are further acted upon in the soil to form macroaggregates. The shift of SOC within microaggregates is beneficial for long-term C sequestration in soil. We also corroborate that the microaggregate protected C is useful as a pool for assessing the impact of tillage management on SOC storage.

Effect of fire intensity on active organic and total soil carbon in a Larix gmelinii forest in the Daxing'anling Mountains,Northeastern China

Studying contents and seasonal dynamics of active organic carbon in the soil is an important method for revealing the turnover and regulation mechanism of soil carbon pool. Through 3 years of field sampling and lab analysis, we studied the seasonal variations, content differences, and interrelationships of total organic carbon （TOC）, light fraction organic carbon （LFOC）, and particulate organic carbon （POC） of the soil in the forest areas burned with different fire intensities in the Daxing＇anling Mountains. The mean TOC content in the low-intensity burned area was greater than that in the unburned area, moderate-intensity, and high-intensity burned areas in June and November （P 〈 0.05）. LFOC and POC in the low-intensity burned area were greater than that in either moderate-intensity or high-intensity burned areas, with significant differences in LFOC in September and November （P 〈 0.05）. A significant difference in LFOC between the unburned and burned areas was only found in July （P 〈 0.05）. However, the differences in POC between the unburned and burned areas were not significant in all the whole seasons （P 〉 0.05）. Soil LFOC and POC varied significantly with the seasons （P 〈 0.05） in the Daxing＇anling Mountains. Significant linear relationships were observed between soil TOC, LFOC, and POC, which were positively correlated with soil nitrogen and negatively correlated with soil temperature in the Daxing＇anling Mountains.

Organic Geochemical Characteristics of Time-Series Settling Particles in Northern South China Sea and Their Implications

Organic carbon, total nitrogen, amino acids, sugars, and chlorophyll were determined in < 1 mm fractions of the samples collected by successive large aperture time-series sediment traps (Honjo-Mark Ⅵ ) in northern China China Sea during September 1987 to October1988. The ratio of C/N and the relative abundance of amino acids and sugars show that organicmatter in the settling particles from northem South China Sea is derived mainly from marineplantkon (especially phytoplankton). The organic carbon fluxes in our sediment traps are lowerthan those in other sediment traps. But the relative contents of Corg/total particulate matter aregenerally similar to those in the Panama Basin, Arabian Sea and Subarctic Pacific. It is suggested that monsoon-caused changes of physical and chemical conditions in the upper euphoticlayer would contro the fluxes of organic matter as well as its composition and transport innorthern South China Sea.

Organic geochemical studies of sinking particulate material in China sea area(I)──Organic matter fluxes and distributional features of hydrocarbon compounds and fatty acids

Sinking particulate material collected from Nansha Yongshu reef lagoon and the continental shelf of the East China Sea by sediment traps has been analyzed and studied for the first time using organic geochemical method. The results show that about half of the sinking particulate organic matter in the two study areas are consumed before reaching the depth of 5 m to the sea floor and the degree of this consumption in Yongshu reef lagoon is larger than that in the continental shelf of the East China Sea. The distributions of hydrocarbons and fatty acids indicate that the minor difference of biological sources of sinking particulate organic matter exists between Yongshu reef lagoon and the continental shelf of the East China Sea, but they mainly come from marine plankton. Stronger biological and biochemical transformations of sinking particulate organic matter are also observed and the intensity of this transformation in Yongshu reef lagoon is greater than that in the continental shelf of the East China Sea. It is found that the occurrence of C 25 highly branched isoprenoid (HBI) diene may be related to the composition of diatom species.

Acceleration of the particulate organic matter hydrolysis by start-up stage recovery and its original microbial mechanism

To address the availability of carbon sources for denitrification,the accelerated hydrolysis of the most abundant but low-availability fraction of particulate organic matter(POM)was investigated.Mesh sieves with different pore sizes were used as primary pretreatment at the start-up-stage of the biological process to separate some POM from the liquid system.The changes in soluble carbohydrates and proteins were monitored to investigate the hydrolysis performance of the sieved POM,with waste activated sludge(WAS)as the control test.The results showed that an average of 35%POM could be entrapped before filtrate mat development.In addition,benefiting from the high polysaccharides concentration,as well as the high availability due to the relatively loose physical structure,a 23%hydrolysis efficiency of POM was obtained,in contrast to that of WAS(3.4%),with a hydrolysis constant of 0.39 h^(−1).The prominent performance was also attributed to the unique microbial communities having been domesticated at a lower temperature,especially the cellulose-degrading bacteria Paraclostridium and psychrophile Psychrobacter,making up 6.94%and 2.56%,respectively.Furthermore,the potential benefits and application of improved POM hydrolysis by start-up stage recovery via mesh sieves combined with anaerobic fermentation were evaluated,including selective POM entrapment,alleviation of blockage and wear,and a reduction in aeration energy.By the proposed strategy,carbon availability for biological nutrient removal(BNR)processes is anticipated to be improved more economically than that can be achieved by primary clarifier elimination.

石灰土易提取球囊霉素相关土壤蛋白的实验条件优化

在水-二氧化碳-碳酸盐岩-生物的相互作用下,全球形成8.24×10^(8)t C/a的岩溶碳汇,其中部分岩溶碳汇以土壤有机质的形式固存,进而在国家双碳目标中发挥重要作用。全球分布广泛的丛枝菌根真菌分泌的球囊霉素相关土壤蛋白(Glomalin-related soil protein,GRSP)性质稳定、不易分解,是土壤有机质的重要组成部分。提取合格的GRSP是深入研究岩溶土壤有机碳汇的基础,然而以往研究因GRSP提取量不高、提取不充分、产物不专一等问题,以至其在有机质中发挥的作用机制无法深入开展研究,因此,提高GRSP提取量对于探究岩溶土壤有机质的形成和稳定机制具有重要意义。本文选取岩溶区黑色、棕色、黄色和红色四种石灰土,通过温度和时间正交实验,筛选出适用于岩溶土壤颗粒态有机质(POM)和矿物结合态有机质(MAOM)易提取球囊霉素相关土壤蛋白(EE-GRSP)的最佳提取条件。实验结果表明,POM和MAOM在123℃和80min条件下提取时,EE-GRSP提取量最高。应用于四类石灰土后,EE-GRSP增量范围为4.6%~34.2%。相较于全土,MAOM具有更高的稳定性与更强的有机碳保护能力。因此,随着温度和提取时间的提高,MAOM中的EE-GRSP得到更完全的释放,提取量显著提高。由此可见,EE-GRSP提取条件优化对深入研究岩溶土壤碳汇潜力及其稳定机制具有重要意义。

乙醇汽油对汽车污染物排放影响研究进展

“双碳”背景下,替代燃料乙醇汽油的推广应用在汽车减污降碳和能源安全领域受到广泛关注.为研究乙醇汽油对汽车污染物和温室气体排放的影响,本研究基于大量文献数据,统计分析了乙醇汽油的使用对汽车尾气常规气态污染物、颗粒物(PM)、温室气体、挥发性有机物(VOCs)以及蒸发排放的影响,并综合评估其对二氧化碳(CO_(2))、PM和VOCs的减排效果,进一步针对典型区域分析乙醇汽油推广应用带来的环境效益.结果表明:①与传统汽油相比,乙醇汽油的使用可以降低尾气中总碳氢化合物(THC)、一氧化碳(CO)、氮氧化物(NOx)、VOCs、PM及其数量的排放,其降幅分别为10.0%、22.0%、1.3%、17.7%、21.3%、14.9%,且减排率均随汽油中乙醇含量的升高而增高,但是有增加VOCs蒸发排放量的趋势.②乙醇汽油对尾气中温室气体的减排效果并不显著,但通过减少化石燃料的使用能在一定程度上减少机动车尾气中CO_(2)的排放.以2022年河南省轻型汽油车保有量为基准,评估了河南省全省推广乙醇汽油(E10汽油)后轻型汽油车CO_(2)、PM及VOCs的减排量,分别为9.1×10^(5)、92.4和1118.1 t/a.研究显示,乙醇汽油的推广使用具有一定的减污降碳协同效益,加强蒸发排放控制能够进一步降低使用乙醇汽油时的污染物排放.