Organic Trace Research Articles

Chemical Characterization of Organic Aerosol Tracers Derived from Burning Biomass Indigenous to Sub-Saharan Africa: Fresh Emissions versus Photochemical Aging

Chemical Characterization of Organic Aerosol Tracers Derived from Burning Biomass Indigenous to Sub-Saharan Africa: Fresh Emissions versus Photochemical Aging

Effects of Trace Mineral Source on Growth Performance, Antioxidant Activity, and Meat Quality of Pigs Fed an Oxidized Soy Oil Supplemented Diet.

This study investigates the effects of oil quality and trace mineral source on the growth performance, antioxidant activity, and meat quality of growing-finishing pigs. A total of 180 crossbred pigs (Duroc × Landrace × Large White [64.4 ± 1.95]) were randomly allocated five dietary treatments based on body weight (BW) and sex in a 30 d trial. Pigs were fed five diets: (i) fresh soy oil + inorganic trace minerals (ITMs) + inorganic selenium (FISI), (ii) oxidized soy oil + ITMs + inorganic selenium (OISI), (iii) fresh soy oil + ITMs + selenium yeast (FISY), (iv) oxidized soy oil + ITMs + selenium yeast (OISY), and (v) oxidized soy oil + organic trace minerals (OTMs) + selenium yeast (OOSY). Each dietary treatment included six replicates and six pigs per replicate (three barrows and three gilts). Feeding OISI resulted in lower average daily gain (ADG) and dressing percentage (p < 0.05). The OOSY group had a higher dressing percentage and activities of serum CAT and GSH-Px in growing-finishing pigs (p < 0.05). In addition, the relative abundance of Campylobacterota in the colonic digesta varied with the quality of soy oil and source of trace minerals (p < 0.05), but no significant differences in short-chain fatty acid concentrations were observed among all dietary groups. In conclusion, adding oxidized soy oil to the diet negatively impacted the ADG and dressing percentage of growing-finishing pigs, and replacing ITMs with OTMs and SY alleviated these negative impacts. A combination of OTMs and SY can support antioxidant capacity to mitigate the negative impacts of oxidized oil on the growth performance and dressing percentage of growing-finishing pigs.

CHARACTERIZATION OF FINE CARBONACEOUS AEROSOLS FROM THE EASTERN MEDITERRANEAN: CONTRIBUTIONS OF FOSSIL AND NON-FOSSIL CARBON SOURCES

ABSTRACT In order to better characterise carbonaceous components in atmospheric aerosols and to assess the contributions of fossil carbon (FC) and non-fossil carbon (NFC) sources and their seasonality in the Eastern Mediterranean, we collected fine (PM1.3) aerosols at a remote marine background site, the Finokalia Research Station, Crete, Greece, over a period of one-year. PM1.3 samples were analysed for elemental carbon (EC), organic carbon (OC), water-soluble OC (WSOC), and stable carbon isotope ratio (δ13CTC) and radiocarbon content (14CTC) (pMC) of total carbon (TC). All the parameters, i.e., PM1.3, δ13CTC and 14CTC showed a clear temporal pattern with higher values in summer and lower values in autumn. The 14CTC ranged from 54.7 to 99.1 pMC with an average of 74.5 pMC during the entire year. The FC content in TC (FCTC) was found to be slightly lower in winter and almost stable in other seasons, whereas the NFC contents (NFCTC) showed a clear seasonality with the highest level in summer followed by spring and the lowest level in winter. Based on these results together with the seasonal distributions of organic tracers, we found that biomass burning (BB) and soil dust are two major sources of the fine aerosols in winter. Although biogenic emissions of VOCs followed by subsequent secondary oxidation processes are significant in summer followed by spring and autumn, pollen is a significant contributor to TC in spring. This study showed that emissions from fossil fuel combustion are significant (25.5%) but minor compared to NFC sources in the eastern Mediterranean.

Surface-derived groundwater contamination in Gulu District, Uganda: Chemical and microbial tracers

Groundwater is consumed by over 2 billion people globally, though it can be impacted by microbial and chemical contamination in both rural and (peri-)urban areas. This issue is particularly pertinent in regions like East Africa, where rapid urbanisation has strained local infrastructure, including water and sanitation systems. We use selected tracers of human and animal waste to assess the quality of community drinking sources with regards to surface-derived groundwater inputs and to compare urban versus rural water quality, under the rapidly developing urban area of Gulu, Northern Uganda. Specifically, we examine bulk and fluorescent dissolved organic matter (DOM), microorganisms (total coliforms, E.coli) and inorganic tracers of anthropogenic waste (NO3−, SO42−, Cl/Br) from various sources: boreholes (12–76 m depth; n = 90), protected springs (n = 11) and municipal taps (n = 4). Our results show that NO3− and SO42− were elevated in groundwater sources in the Gulu city urban area and the Cl/Br ratio was elevated in springs, compared to concentrations in the more rural Aswa and Omoro County area (p < 0.05). Interestingly, human and animal waste indicators E.coli and Tryp:FA (the ratio of tryptophan-like to fulvic-like fluorescence) displayed no significant difference between rural and urban settings (p > 0.05), though total coliforms were significantly higher in rural boreholes (p < 0.05). The presence of a pollution source, pollution carrier and a breakdown of a sanitary barrier at the borehole, as spot-checked by a visual sanitary risk assessment, was significantly associated with groundwater E.coli abundances. Evidence suggests monitoring and mitigation should be improved for all water types in Gulu District to meet WHO and Uganda Standard guidelines for potable water. This study offers valuable insights for water management planning and risk assessment of community water sources particularly in the context of East Africa and similar settings.

Organic Trace Minerals Enhance the Gut Health of British Shorthair Cats by Regulating the Structure of Intestinal Microbiota.

Trace minerals are essential for biological processes, including enzyme function, immune response, and hormone synthesis. The study assessed the effects of different dietary trace minerals on the gut health, microbiota composition, and immune function of cats. Eighteen adult British Shorthair cats were divided into three groups receiving inorganic trace minerals (ITM), a 50/50 mix of inorganic and organic trace minerals (ITM + OTM), or organic trace minerals (OTM) for 28 days. The OTM showed enhanced immune capacities, reduced intestinal barrier function, and lower inflammation condition. The OTM altered gut microbiota diversity, with a lower Simpson index and higher Shannon index (p < 0.05). Specifically, the abundance of Bacteroidota, Lachnospiraceae, and Prevotella in the OTM group were higher than the ITM group (p < 0.05). Metabolomic analysis identified 504 differential metabolites between the OTM and ITM groups (p < 0.05, VIP-pred-OPLS-DA > 1), affecting pathways related to steroid hormone biosynthesis and glycerophospholipid metabolism (p < 0.05, VIP-pred-OPLS-DA > 2). Additionally, there was a significant correlation between intestinal microbiota and differential metabolites. To conclude, dietary OTM can modulate the gut metabolite and microbiota composition, enhance immune and intestinal barrier function, and mitigate inflammation in cats, highlighting the benefit of using OTM in feline diet to promote the intestinal and overall health.

Overlooked Trace Molecules in Organic Aerosol Revealed by Gas Chromatography-Orbitrap Mass Spectrometry.

Molecular characterization of organic aerosol (OA) is crucial for understanding its sources and atmospheric processes. However, the chemical components of OA remain not well constrained. This study used gas chromatography-Orbitrap mass spectrometry (GC-Orbitrap MS) and GC-Quadrupole MS (GC-qMS) to investigate the organic composition in PM2.5 from Xi'an, Northwest China. GC-Orbitrap MS identified 335 organic tracers, including overlooked isomers and low-concentration molecules, approximately 1.6 times more than GC-qMS. The "molecular corridor" assessment shows the superior capability of GC-Orbitrap MS in identifying an expansive range of compounds with higher volatility and oxidation states, such as furanoses/pyranoses, di/hydroxy/ketonic acids, di/poly alcohols, aldehydes/ketones, and amines/amides. Seasonal variations in OA composition reflect diverse sources: increased di/poly alcohols in winter are derived from indoor emissions, furanoses/pyranoses and heterocyclics in spring and summer might be from biogenic emissions and secondary formation, and amides in autumn are probably from biomass burning. Integrating partial least squares discriminant analysis (PLS-DA) and potential source contribution function (PSCF) models, the source similarities and differences are further elucidated, highlighting the role of local emissions and transport from southern cities. This study offers new insights into the OA composition aided by the high mass resolution and sensitivity of GC-Orbitrap MS.

Fluorescence characteristics of organic tracer molecules for planar laser-induced fluorescence in internal combustion engines, Part B: aromatics

Fluorescence characteristics of organic tracer molecules for planar laser-induced fluorescence in internal combustion engines, Part B: aromatics

PSVI-20 Supplementing cows with an organic trace mineral drench at CIDR placement improved artificial insemination pregnancy rates

PSVI-20 Supplementing cows with an organic trace mineral drench at CIDR placement improved artificial insemination pregnancy rates

Fluorescence characteristics of organic tracer molecules for planar laser-induced fluorescence studies in internal combustion engines, part A: non-aromatics

Fluorescence characteristics of organic tracer molecules for planar laser-induced fluorescence studies in internal combustion engines, part A: non-aromatics

Impact of the biogas impurities on the quality of the precipitated calcium carbonate in the regenaration stage of a chemical absorption biogas upgrading unit

Combining Carbon Capture and Storage (CCS) with producing competitive secondary raw materials is key to decarbonizing industry and reducing resource extraction. Biogas upgrading to biomethane stand out as an alternative, but a significant gap remains in integrating this process within a circular economy framework. This issue has been recently addressed by a process that integrates biogas upgrading via caustic absorption with the production of Precipitated Calcium Carbonate (PCC) and the recovery of sodium hydroxide from waste brine solution using membrane technologies. The profitability of this approach depends on the quality of the PCC, a critical factor that this work addresses. By characterizing PCC is determined whether trace compounds in biogas contaminate the PCC and potentially affect its commercial value. It also examines the CO2 absorption process and analyzes the aqueous samples from the filtration phase of the PCC slurry. Results confirm the high purity of PCC obtained from biogas treatment using Raman spectroscopy, X-Ray Diffraction (XRD), and Scanning Electron Microscopy (SEM). The analyses show that the PCC is pure calcium carbonate, mainly in the stable calcite form, with a typical tetrahedral morphology and no detectable impurities. Characterization of aqueous solutions revealed organic trace compounds from biogas, with TOC concentrations of 9.7 (± 6.4) and 16.0 (± 8) mg C/l. Silicon measurements showed similar concentrations in the absorbent solution and filtrated PCC slurry. Additionally, ammonia escapes as gas, and hydrogen sulfide in the biogas likely contributed to sulfate salt formation. Analysis of the CO₂ absorption shows a first-order reaction with OH-, where the amount of CO₂ absorbed (46.3–50.0 g) closely matches the theoretical value of 48 g. The study reveals that most of the biogas impurities dissolve into the aqueous solution, being crucial for future studies and downstream membrane treatments, and the PCC is unaffected by these impurities with a purity suitable for commercial applications.

Effect of organic and nano trace minerals at reduced levels in layer diets on egg quality characteristics and its trace mineral content

An experiment was conducted to assess the effect of organic and nano trace minerals (copper, zinc, manganese and iron) at reduced levels in layer diets on various egg quality characteristics and its trace mineral content. 240 Hy- Line W80 layer birds of 29 weeks old were randomly distributed to five treatment groups with four replicates having twelve birds each. Basal diet was supplemented with inorganic trace minerals to meet 100 per cent requirement to form control diet or with organic trace minerals at 75 and 50% of requirement or with nano trace minerals at 50 and 25% of requirement to form four test diets. Each diet was offered to four replicate groups for 84 days which was conveniently divided into three phases of 28 days each. Egg quality parameters, viz. egg weight, egg shape index, albumen index, yolk index, yolk color score, Haugh unit score, egg shell weight, albumen weight and yolk weight among the treatment groups were not affected by source and level of trace minerals. However, egg shell thickness was significantly higher in 25% nano trace mineral group on 28th day. The trace minerals (Zn and Fe) in the yolk were significantly lower at reduced trace mineral levels (50% organic or nano and 25% nano form) when compared to 100% (inorganic) and 75% levels (organic form). It was concluded that the substitution of inorganic trace minerals with organic or nano trace minerals at reduced levels (50 or 25%, respectively) in layer diets does not affect the egg quality parameters, but reduces Zn and Fe content in egg yolk.

The effects of coated inorganic trace minerals on the growth performance, mineral retention, and intestinal health comparing with inorganic and organic trace minerals for juvenile American eels (Anguilla rostrata)

This study was conducted to compare the effects of coated inorganic trace minerals (CITM) with those of inorganic and organic trace minerals on the growth performance, mineral retention in the whole-body, and intestinal health of juvenile American eels (Anguilla rostrata). Eels were randomly divided into the inorganic trace minerals (ITM) group, organic trace minerals (OTM) group, coated inorganic trace minerals I (CITM I) group, and coated inorganic trace minerals II (CITM II) group, respectively. The supplementation level of trace minerals in the CITM II group was 50 % of those in the CITM I group. Eels were fed experimental diets for ten weeks. Compared with the ITM group, weight gain rate, specific growth rate, protein efficiency, and feed efficiency of those in the CITM I and CITM II groups were increased. Eels in the CITM I group exhibited higher retention rates of calcium, phosphorus, and zinc in whole body than those in the ITM and OTM groups. CITM I group displayed the increased levels of high-density lipoprotein cholesterol, immunoglobulin M, and D-lactic acid compared to the ITE group. Compared with the ITM and OTM groups, CITM I and CITM II groups showed enhanced intestinal histology and activities of intestinal amylase, lipase, and glutathione peroxidase (GSH-Px), coupled with an increase of GSH content. Proteome analysis demonstrated that, compared to the ITE group, CITM I group displayed enhanced intestinal protein abundance associated with vitamin digestion and absorption, fat digestion and absorption, cysteine and methionine metabolism, and amino acid biosynthesis. In conclusion, CITM is more beneficial for the growth performance, mineral retention in the whole-body, and intestinal health of juvenile American eels compared to ITM and OTM sources. Our findings provide valuable insights into the application of the coated trace minerals sources in the diets for American eels and potentially for other fish species.

Anthropogenic sources and liquid water drive secondary organic aerosol formation over the eastern Himalaya

Atmospheric aerosols have a serious impact on altering the radiation balance of the vulnerable Himalayan atmosphere. Organic aerosol (OA), one of the least resolved aerosol fractions in the Himalayas, constrain our competence to assess their climate impacts on the region. Here we investigate water-soluble OA molecules in PM10 samples collected from March to May 2019 at Lachung (27.4°N and 88.4°E), a high-altitude location (2700 m a.s.l.) in the eastern Himalaya, to elucidate their origin and formation process. The dominance of oxalic acid (C2) reveals that water-soluble OA in the eastern Himalaya are atmospherically processed. Backward air mass trajectories and mass concentration ratios of organic tracers as well as relationships with inorganic species (K+, SO42−, NH4+) suggest an anthropogenic origin of water-soluble OA with significant atmospheric processing during long-range transport to the eastern Himalayan region. We used the thermodynamic prediction of aerosol liquid water (ALW) to examine the formation mechanism of secondary OA (SOA) such as oxalic acid. Correlations of ALW with SO42− and water-soluble organic matter show that ALW is sensitive to both anthropogenic sulfate and water-soluble organic compounds in Himalayan aerosols. A strong positive relationship of C2 acid with predicted ALW provides evidence of extensive SOA formation from precursors via aqueous phase photochemical processes. This inference is supported by positive correlations of C2 acid relative abundance with diagnostic mass concentration ratios of C2 acid to precursor molecules. Our findings underscore the importance of anthropogenic sources and ALW in SOA formation through aqueous phase processes in the eastern Himalaya.

Beneficial effects of advanced chelate technology-based 7-minerals in aflatoxin-B1 challenged broilers: toxin residue reduction, serum biochemical improvement and modulation of the mRNA expression of NF-kB and Nrf2, and genes within their pathways.

Organic trace minerals (TM) offer superior nutritional benefits because of their stable structure, making their addition to broiler diets potentially beneficial during challenging periods such as aflatoxin B1 (AFB1) contamination. The present study evaluated the impacts of different replacement levels of inorganic TM (ITM) with advanced chelate technology-based TM (ACTM) on the growth performance, serum biochemical parameters, antioxidant indicators, and some inflammatory and immune parameters of broilers fed diets contaminated with AFB1. A 42-day experiment involved randomly assigning 1-day-old broiler chickens (n = 480) to one of five dietary treatments, each with six replicates. The treatments were as follows: (1) NC: basal diet without AFB1 and recommended ITM levels; (2) PC: basal diet with 0.5 mg kg-1 AFB1 and recommended ITM levels; (3) TB: PC diet +1 g kg-1 toxin binder; (4) ACTM50: replacement of ITM with 50% ACTM in the PC diet; and (5) ACTM100: replacement of ITM with 100% ACTM in the PC diet. Compared with PC treatment, ACTM100 treatment resulted in increased (P < 0.05) body weight gain, serum zinc and glutathione concentrations, immunoglobulin Y level, antioxidant enzyme activities, and hepatic gene expression of nuclear factor erythroid 2-related factor 2, glutathione peroxidase-1, superoxide dismutase-1 and transforming growth factor beta 1. The ACTM100 group also exhibited decreased AFB1 residue in the liver and kidney, serum alanine transaminase activity and malondialdehyde concentration, and hepatic gene expression levels of nuclear factor-kappa B and interferon-gamma (P < 0.05). These values were comparable to those recorded in the TB and NC treatments. In conclusion, completely replacing ITM with ACTM can benefit the metabolism and mitigate AFB1-induced immunotoxicity and oxidative damage in chickens by altering the mRNA expression of nuclear factor-kappa B and nuclear factor erythroid 2-related factor 2, and some genes downstream their signaling pathways. © 2024 Society of Chemical Industry.

Insights into the catalytic effect of atmospheric organic trace species on the hydration of Criegee intermediates

The bimolecular reactions between Criegee intermediates (CIs) and atmospheric trace species have been extensively investigated, with a particular focus on the reaction with water, while the catalytic role of atmospheric organic compounds in hydration reactions was often neglected. In this study, we employed quantum chemical calculations and Born-Oppenheimer molecular dynamics (BOMD) simulations to investigate the catalytic effects of atmospheric organic amines, organic acids, and alcohols on the hydration reactions of CIs in the gas phase and at the gas-liquid interface. The catalytic reactions were found to follow a cyclic catalytic structure and a stepwise reaction mechanism. Gas-phase studies revealed that organic acids exhibited stronger catalytic effects compared to amines and alcohols, and the catalytic efficiency of amines and alcohols was similar to those of single water molecule. In addition, the catalytic reaction barriers of organic acids and alcohols were positively correlated with their gas-phase acidity (R2 = 0.94 to 0.97). A negative correlation was observed between the catalytic reaction barrier of amines and their gas-phase basicity (R2 = 0.84 to 0.90) and proton affinity (R2 = 0.84 to 0.92). At the gas-liquid interface, organic acids promoted the formation of hydroxyethyl hydroperoxide (HEHP, CH3CH(OH)(OOH)), organic acid ions, and H3O+, whereas the catalytic hydration of CIs by organic amines resulted in the formation of CH3CH(OH)OO and amine ions. Both HEHP and CH3CH(OH)OO can be further decomposed to form OH and HO2, or participate in new particles formation as precursors. This study complements the research gap on the reaction of CIs with water, providing valuable insights into the atmospheric sources of HEHP and HOx as well as the formation of secondary organic aerosols (SOAs).

Evaluating the Impact of an Organic Trace Mineral mix on the Redox Homeostasis, Immunity, and Performance of Sows and their Offspring.

The objective of the study was to evaluate the effects of trace mineral supplementation in sows during gestation and lactation on the performance and health status of sows and their offspring. Sows (n = 30; Landrace × Yorkshire; avg parity = 3.9) were randomly allocated into two dietary treatments. Sows received a basal diet supplemented with 12mg/kg Cu, 30mg/kg Fe, 90mg/kg Zn, 70mg/kg Mn, 0.30mg/kg Se, and 1.5 mg/kg I from an inorganic trace mineral source (ITM) or a blend of hydroxychloride and organic trace mineral source (HOTM) from day 1 of gestation until the end of the lactation period at day 21. Compared to the ITM, the HOTM supplementation increased (P < 0.05) both litter birth weight and individual piglet birth weight. Although not statistically significant, HOTM tended to increase (P = 0.069) the level of lactose in colostrum. HOTM increased (P < 0.05) the concentration of Mn and Se in the colostrum, milk, and serum of sows and/or piglets. Notably, the Zn concentration in the serum of sows was higher in sows supplemented with ITM compared to HOTM. Moreover, HOTM increased (P < 0.05) the activities of GPX and SOD in gestating sows and piglets, as well as increased (P < 0.05) cytokines (IL-1β, TNF-α, and IL-10) in the serum of sows. The immunoglobulins (IgA, IgG, and IgM) also increased in sows and/or piglets at certain experimental time points. In conclusion, HOTM supplementation positively affected piglet development and improved the health status of sows and piglets potentially by regulating redox homeostasis and immunity.

Characterization of biomass burning tracers in particulate matter at 12 sites in China: Significant increase of coal combustion emitted levoglucosan in northern China during winter

Biomass burning (BB) is the largest contributor to carbonaceous aerosols globally. Specific organic tracers can track BB particles and identify BB types. At present, there is limited information on the composition of BB tracers on a continental scale. In this study, we conducted year-round sampling of particulate matter (PM) at 12 sites in China. Nine BB tracers were measured in PM with aerodynamic diameters <1.1 μm (PM<1.1), in the range of 1.1–3.3 μm (PM1.1–3.3), and > 3.3 μm (PM>3.3). The annual average concentration of these nine BB tracers (∑9 BB tracers) in the total PM was 366 ng m−3 with the majority of levoglucosan (66 %). The concentration of ∑9 BB tracers was higher in northern China than in southern China, especially in winter. ∑9 BB tracers were most enriched in PM<1.1 (50–61 % in mass), followed by PM1.1–3.3 and PM>3.3. The highest concentrations of ∑9 BB tracers were observed in winter, while satellite-recorded fire spots were intensive in autumn and spring. The mismatch of seasonal trends between them indicated that the high levels of BB tracers in winter was not due to open BB. The composition of 4-hydroxybenzoic acid, syringic acid and vanillic acid suggested that the burning of crop residues and softwoods were the major BB types in China. The ratio of levoglucosan to mannosan could neither identify the major BB types in China nor distinguish between BB and coal combustion. Correlation analysis and the PMF model demonstrated that non-BB sources contributed 7 %–58 % to levoglucosan at the 12 sites, with coal combustion being the predominant non-BB source in China, especially in northern urban sites during winter. Our findings suggest that caution should be taken in application of these organic tracers to identify BB types and estimate BB aerosols.

Source apportionment of fine particulate matter in middle Indo-Gangetic Plain by coupled radiocarbon –molecular organic tracer method

Despite significant emissions of fine particulate matter (FPM) from the Indo-Gangetic Plain (IGP) that affect the climate and air quality in the region, the sources of these emissions are not adequately addressed. This research uses a combined radiocarbon-molecular organic tracer technique to investigate the degree of contamination, seasonal fluctuations, and contribution of FPM in the middle IGP (Patna), India. The findings indicated levoglucosan (L) as the single primary BB tracer chemical, ranging from 149 ng/m3 to 490 ng/m3 (median 282 ng/m3). Winter (median 462 ng/m3) showed a 2–3 times higher level of L than the monsoon season (median 180 ng/m3). A significant association of L with other organic tracers such as galactosan (G), mannosan (M), vallinic acid, syringic acid, p-hydroxybenzoic acid (pHA) and dehydroabietic acid (DHAA)(r = 0.53 to 0.89, p < 0.05), and moderate connection with Cl− (r = 0.21, p < 0.05), SO42− (r = 0.29, p < 0.05), and NO3- (r = 0.22, p < 0.05) indicated significant BB contribution. However, non-sea salt (nss-K+) was not related to L. Based on seven days of air mass back trajectories and MODIS active fire counts analysis, we conclude that OAs composition is not the local origin but is also impacted by long-range atmospheric transport from Pakistan/Afghanistan, followed by the Bay of Bengal and the Arabian Sea. Chemical analysis of organic tracers and positive matrix factorization (PMF) modeling study identified three unique sources, i.e., biomass burning, secondary aerosols formation, and mixed type (fossil fuels and construction dust) as the primary source of FPM in Patna, accounted for 46.1 %, 28.9 %, and 24.9 %, of total emissions, respectively. The radiocarbon (14 C) analysis of total carbon (TC) samples further supported this conclusion. The results of the 14 C study indicated that emissions from BB, such as wood and stubble, were responsible for 57% of the TC concentration.

Annual variation of source contributions to PM10 and oxidative potential in a mountainous area with traffic, biomass burning, cement-plant and biogenic influences

Toxicity of particulate matter (PM) depends on its sources, size and composition. We identified PM10 sources and determined their contribution to oxidative potential (OP) as a health proxy for PM exposure in an Alpine valley influenced by cement industry. PM10 filter sample chemical analysis and equivalent black carbon (eBC) were measured at an urban background site from November 2020 to November 2021. Using an optimized Positive Matrix Factorization (PMF) model, the source chemical fingerprints and contributions to PM10 were determined. The OP assessed through two assays, ascorbic acid (AA) and dithiothreitol (DTT), was attributed to the PM sources from the PMF model with a multiple linear regression (MLR) model. Ten factors were found at the site, including biomass burning (34, 40 and 38% contribution to annual PM10, OPAA and OPDDT, respectively), traffic (14, 19 and 7%), nitrate- and sulphate-rich (together: 16, 5 and 8%), aged sea salt (2, 2 and 0%) and mineral dust (10, 12 and 17%). The introduction of innovative organic tracers allowed the quantification of the PM primary and secondary biogenic fractions (together: 13, 8 and 21%). In addition, two unusual factors due to local features, a chloride-rich factor and a second mineral dust-rich factor (named the cement dust factor) were found, contributing together 10, 14 and 8%. We associate these two factors to different processes in the cement plant. Despite their rather low contribution to PM10 mass, these sources have one of the highest OPs per µg of source. The results of the study provide vital information about the influence of particular sources on PM10 and OP in complex environments and are thus useful for PM control strategies and actions.

Organic Trace Elements Improve the Eggshell Quality via Eggshell Formation Regulation during the Late Phase of the Laying Cycle.

The quality of eggshells is critical to the egg production industry. The addition of trace elements has been shown to be involved in eggshell formation. Organic trace elements have been found to have higher biological availability than inorganic trace elements. However, the effects of organic trace elements additive doses on eggshell quality during the laying period of commercial laying hens required further investigation. This experiment aims to explore the potential mechanisms of different doses of organic trace elements replacing inorganic elements to remodel the eggshell quality of egg-laying hens during the laying period. A total of 360 healthy hens (Lohmann Pink, 45-week-old) were randomly divided into four treatments, with six replications per treatment and 15 birds per replication. The dietary treatments included a basal diet supplemented with inorganic iron, copper, zinc and manganese at commercial levels (CON), a basal diet supplemented with organic iron, copper, zinc and manganese at 20% commercial levels (LOT), a basal diet supplemented with organic iron, copper, zinc and manganese at 30% commercial levels (MOT), and a basal diet supplemented with organic iron, copper, zinc and manganese at 40% commercial levels (HOT). The trial lasted for 8 weeks. The results of the experiment showed that the replacement of organic trace elements did not significantly affect the production performance of laying hens (p > 0.05). Compared with inorganic trace elements, the MOT and HOT groups improved the structure of the eggshells, enhanced the hardness and thickness of the eggshells, increased the Haugh unit of the eggs, reduced the proportion of the mammillary layer in the eggshell, and increased the proportion of the palisade layer (p < 0.05). In addition, the MOT and HOT groups also increased the enzyme activity related to carbonate transport in the blood, the expression of uterine shell gland-related genes (CA2, OC116, and OCX32), and the calcium and phosphorus content in the eggshells (p < 0.05). We also found that the MOT group effectively reduced element discharge in the feces and enhanced the transportation of iron (p < 0.05). In conclusion, dietary supplementation with 30-40% organic micronutrients were able to improve eggshell quality in aged laying hens by modulating the activity of serum carbonate transport-related enzymes and the expression of eggshell deposition-related genes.