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Iron (Fe) plays a fundamental role in coral symbiosis, supporting photosynthesis, respiration, and many important enzymatic reactions. However, the extent to which corals are limited by Fe and their metabolic responses to inorganic Fe enrichment remains to be understood. We used respirometry, variable chlorophyll fluorescence, and O2 microsensors to investigate the impact of increasing Fe(III) concentrations (20, 50, and 100 nM) on the photosynthetic capacity of two Mediterranean coral species, Cladocora caespitosa and Oculina patagonica. While the bioavailability of inorganic Fe can rapidly decrease, we nevertheless observed significant physiological effects at all Fe concentrations. In C. caespitosa, exposure to 50 nM Fe(III) increased rates of respiration and photosynthesis, while the relative electron transport rate (rETR(II)) decreased at higher Fe(III) exposure (100 nM). In contrast, O. patagonica reduced respiration, photosynthesis rates, and maximum PSII quantum yield (Fv/Fm) across all iron enrichments. Both corals exhibited increased hypoxia (<50 µmmol O2 L-1) within their gastric cavity at night when exposed to 50 and 100 nM Fe(III), leading to increased polyp contraction time and reduced O2 exchange with the surrounding water. Our results indicate that C. caespitosa, but not O. patagonica, might be limited in Fe for achieving maximal photosynthetic efficiency. Understanding the multifaceted role of iron in corals' health and their response to environmental change is crucial for effective coral conservation. [ABSTRACT FROM AUTHOR]

Iron (Fe) plays a fundamental role in coral symbiosis, supporting photosynthesis, respiration, and many important enzymatic reactions. However, the extent to which corals are limited by Fe and their metabolic responses to inorganic Fe enrichment remains to be understood. We used respirometry, variable chlorophyll fluorescence, and O2 microsensors to investigate the impact of increasing Fe(III) concentrations (20, 50, and 100 nM) on the photosynthetic capacity of two Mediterranean coral species, Cladocora caespitosa and Oculina patagonica. While the bioavailability of inorganic Fe can rapidly decrease, we nevertheless observed significant physiological effects at all Fe concentrations. In C. caespitosa, exposure to 50 nM Fe(III) increased rates of respiration and photosynthesis, while the relative electron transport rate (rETR(II)) decreased at higher Fe(III) exposure (100 nM). In contrast, O. patagonica reduced respiration, photosynthesis rates, and maximum PSII quantum yield (Fv/Fm) across all iron enrichments. Both corals exhibited increased hypoxia (

This work reports a method and findings related to the enrichment of iron from bauxite waste (red mud) using chemical looping combustion (CLC). According to the results from X‐ray Diffraction, X‐ray Fluorescence, and scanning electron microscope–energy‐dispersive X‐ray spectroscopy, uniformly distributed iron in the red mud particles migrated outward to the surface during the 148 redox cycles in a bubbling fluidized bed reactor, in which the size‐reduced iron‐oxide particles due to attrition are concentrated in filters. The concentrations of iron oxide in raw particles and attrition fines are 43 wt.% and 83–87 wt.%, respectively. Since the attrition in CLC is inevitable, this recycled iron oxide can be a valuable by‐product to compensate for the cost of CLC, whereas the bed materials continue to participate in the CLC process. Moreover, the abundant bauxite waste can be processed in an eco‐friendly manner for integrated power generation, carbon capture, and iron recovery by the proposed strategy in this work. [ABSTRACT FROM AUTHOR]

This study compared the effects dietary organic (ferrous glycine [FG]) versus inorganic (ferrous sulfate [FS]) iron in laying hens on performance, egg quality, serum and egg yolk lipids, antioxidant status, and iron enrichment of eggs. A total of 378 Shaver White layers were allotted to 7 treatments with 6 replicates (9 birds each) from 30 to 42 weeks of age. A basal diet (19 mg iron/kg) served as control, while the other six diets were supplemented with either FS or FG to provide 30, 60, and 120 mg/kg of added iron. Dietary FG and FS treatments improved (P < 0.05) laying rate, egg weight, and egg quality of layers, relative to the control, albeit eggshell strength and eggshell calcium also deteriorated with the highest level of FS (P < 0.05). The iron treatment groups exhibited a lower serum and egg yolk levels of triglycerides, total cholesterol, and low-density lipoprotein cholesterol that accompanied by higher levels of high-density lipoprotein cholesterol and greater activities of superoxide dismutase (SOD) and glutathione peroxidase (GPx) as compared with the control (P < 0.05). The contents of malondialdehyde and protein carbonyl were conversely related to the activities SOD and GPx (P < 0.05). The serum and egg fractions (yolk, albumen, and shell) displayed gradually increases in iron contents as the level of iron increased in the diet (P < 0.05), while FG was superior to FS at all tested levels (P < 0.05). To summary, FS can be replaced by FG, with more favorable impacts on egg quality and iron enrichment. [ABSTRACT FROM AUTHOR]

This study was conducted to evaluate the effects of iron glycine chelate (Fe-Gly) on egg quality of laying hens. A total of 810 laying hens (HyLine Variety White, 26 wk old) were randomly assigned to 6 groups, and each group consisting of 135 hens (5 replicates of 27 hens each). Hens in the control group received a diet supplemented with 60 mg Fe/kg as FeSO4, whereas hens in the other 5 groups received diets supplemented with 0, 20, 40, 60, and 80 mg Fe/kg from Fe-Gly, respectively. The study showed that dietary Fe-Gly treatments influenced (P < 0.05) the internal egg quality (egg weight, Haugh unit, albumen height), compared with the control group. However, dietary Fe-Gly supplementation showed few effects on the ultrastructure of eggshell in this study. The group of 60 mg Fe/kg as Fe-Gly was promoted (P < 0.05) in succinate dehydrogenase levels of liver and spleen compared with the 0 mg Fe-Gly/kg group, whereas the control (Fe/kg as FeSO4) group has no differences compared with the 0 mg Fe-Gly/kg group. The concentrations of Fe in the eggshell, yolk, and albumen were increased with increasing concentrations of Fe-Gly, where Fe-Gly (60, 80 mg Fe/kg) had higher (P < 0.01) Fe concentration than the control in yolk and albumen. The Fe-Gly groups (60, 80 mg Fe/kg) were influenced (P < 0.05) in transferrin, divalent mental transport 1, and ferroportin 1, compared with the control (FeSO4). In conclusion, Fe-Gly (60 mg Fe/kg) improved egg quality and egg iron enrichment. In general, there were no significant differences between Fe-Gly (40) and the control group in albumen height, Haugh unit, Fe concentration in eggshell and yolk. It revealed that FeSO4 could be substituted by a lower concentration of Fe-Gly and Fe-Gly may be superior to FeSO4 for egg quality in laying hens. [ABSTRACT FROM AUTHOR]

The present study was conducted to investigate the effects of different levels of pomegranate byproduct (PBP) on performance, egg quality and blood parameters in laying hens. A total of 144 Bobze layer hens from 44 to 56 weeks during 12 weeks were randomly assigned into 4 treatments including 0 (control, corn and soy bean meal), 4, 8 and 12% of PBP, with 4 replicates and 9 layers in each. Results have indicated that there was a significant increase in egg mass, egg production the decrease in feed intake and feed conversion ratio by 4% PBP in comparison to other treatments (P<0.05). Significantly increased egg weight by inclusion of 8% PBP compared with 0 and 12% PBP. There was no significant effect of PBP levels on external and internal egg characteristics. The lowest cholesterol and the higher high-density lipoprotein and malondialdehyde have shown by 4% PBP (P<0.05). The highest amount of iron in egg yolk was observed respectively by treatments 4 and 12% PBP. It was concluded that egg yolk iron and production rate were increased by 4% PBP supplementation in diet. [ABSTRACT FROM AUTHOR]

Surface dissolved dimethylsulfide (DMS) and depth-integrated dimethylsulfoniopropionate (DMSP) measurements were made from March to April 2004 during the SOLAS Air–Sea Gas Exchange Experiment (SAGE), a multiple iron enrichment experiment in subantarctic waters SE of New Zealand. During the first two iron enrichments, chl a and DMS production were constrained, but during the third enrichment, large pulses of DMS occurred in the fertilised IN patch, compared with the unfertilised OUT patch. During the third and fourth iron infusions, total chl a concentrations doubled from 0.52 to 1.02 µg/L. Hapto8s and prasinophytes accounted for 50%, and 20%, respectively, of total chl a. The large pulses of DMS during the third iron enrichment occurred during high dissolved DMSP concentrations and wind strength; changes in dinoflagellate, haptophyte, and cyanobacteria biomass; and increased microzooplankton grazing that exerted a top down control on phytoplankton production. A further fourth iron enrichment did cause surface waters to increase in DMS, but the effect was not as great as that recorded in the third enrichment. Differences in the biological response between SAGE and several other iron enrichment experiments were concluded to reflect microzooplankton grazing activities and the microbial loop dominance, resulting from mixing of the MLD during storm activity and high winds during iron enrichment.

Magnetic biochars are implicated in graphene micro-crystallite formation, soil redox processes and highly adsorbent chars. This study investigates the mechanisms of bamboo charring – when impregnated with FeSO 4 ·7H 2 O – at 250, 350, 450 and 550 °C, using thermal and static techniques. Impregnation resulted in the oxidation of Fe 2+ to mixed Fe 3+ /Fe 2+ (magnetite) oxide forms during pyrolysis. A reaction sequence was proposed in which Fe-sulphates were incorporated with an ammonia catalyst. Sulphur became ubiquitous in both inorganic and organic forms, and additional minerals also formed. Stable aromatics and separation of holo-cellulosic and degraded lignin volatilisation phases were catalysed, and carboxylation was inhibited. Concentrations of C fluctuated more substantially, before stabilising at high HTTs. Pyrolysis temperatures of 450 °C and above appear to maximise stable C concentrations.These observations indicated that this treatment may yield agriculturally engineered chars with enhanced redox potential, more neutral pH, and a range of nutrients. [ABSTRACT FROM AUTHOR]

This paper reports the effect of dissolved iron (dFe) and dust additions on the Biological Carbon Fixation (BCF) rates in the surface layer of the central Gulf of California (GC). Two on deck experiments were conducted in the summer of 2016 at an oceanographic station located in the Guaymas Basin. Each experiment consisted in the incubation of natural phytoplankton assemblages collected at three distinct depths within the upper 50 m layer and amended either with iron (FeCl 3) or dust leachate, followed by the quantification of BCF rates using the 13C assimilation method. A very warm (∼30 °C) water column strongly stratified and with reduced phytoplankton biomass (<1 mg chlorophyll a m−3) was indicative of an oligotrophic environment. In addition, the surface levels of NO 3 −+NO 2 − (<0.1 μM), dFe (1.71 ± 1.04 nM), as well as the Fe:N (78 ± 47 nmol μmol−1) and N:P (0.04 ± 0.01) ratios revealed that phytoplankton was under conditions of inorganic nitrogen limitation. BCF rates measured during the experiments ranged between 0.46 ± 0.04 and 6.24 ± 0.34 mg C m−3 h−1 with the highest values at the maximum of fluorescence and their vertical distribution was associated with the carbon biomass of picophytoplankton and diatoms. Despite the oligotrophic condition that predominated during the cruise, most of the Fe or dust additions did not show a significant effect (p > 0.05) on the magnitude of BCF rates, which was attributed to the fact that N, rather than Fe, was the limiting nutrient for phytoplankton production. However, Fe limitation cannot be completely ruled out as two samples (one for each treatment) showed a significant increase (p < 0.05) in BCF rates. We suggest that atmospheric supply of dust during the summer could play a relevant biological role maintaining high concentrations of dFe (and other bioactive metals) in the surface waters of central GC. • The dissolved Fe effects on the summer C fixation rates in the GC are reported. • Cell abundance in the upper water column was dominated by picoautotrophs. • High thermal stratification and low chlorophyll a indicated oligotrophic conditions. • A deficit of nitrate predominated in seawater at the time of the experiments. • Nitrogen limitation prevents the effects of Fe addition on summer C fixation rates. [ABSTRACT FROM AUTHOR]

65 Ma Deccan Volcanic Province of western India forms one of the largest flood basaltic eruptions on the surface of the earth. The nature of the concealed crust below this earthquake prone region, which is marked by several low velocity zones at different depths has hardly been understood. These low velocity zones have been invariably interpreted as fluid-filled zones, genetically connected to earthquake nucleation. While carrying out detailed geological and petrophysical studies on the Late Archean basement cores, obtained from a 617 m deep KLR-1 borehole, drilled in the epicentral zone of 1993 Killari earthquake region of the southern Deccan Volcanic Province, we came across several instances where we observed remarkable drop in measured P-wave velocity in a number of high density cores. We provide detailed petrographic and geological data on 11 such anomalous samples which belong to mid-crustal amphibolite to granulite facies transitional rocks. They are associated with a mean P-wave velocity of 6.02 km/s (range 5.82-6.22 km/s) conforming to granitic upper crust, but in contrast have a high mean density of 2.91 g/cm (range 2.75-3.08 g/cm), which characterise mid to lower crust. This velocity drop, which is as much as 15 % in some cores, is primarily attributed to FeO enrichment (up to about 23 wt%) during the course of mantle-fluid driven retrogressive metasomatic reactions, caused by exhumation of deep-seated mafic rocks. Presence of Iron content (mainly magnetite), widely seen as opaques in thin sections of the rocks, seems to have resulted into sharp increase in density, as well as mean atomic weight. Our study indicates that the measured V is inversely related to FeO content as well as mean atomic weight of the rock. [ABSTRACT FROM AUTHOR]

Wheat flour (WF) of 85% meal extraction was blended with/without 50g defatted soybean flour (DSF)/kg and enriched with 50 or lOOmg iron/kg diet used in vitro and In vivo study of protein digestibility, Sixty male weanling albino rats were used as a biological model for this study. Rats were divided into two major equal groups, First group as healthy control rats and second group as iron depleted rats. Each group was subdivided into six groups according to their body mass (BM), These subgroups fed experimental diets for 10 days. Digestible protein (%) and its digestibility index, rat BM gain and its growth index were estimated using in vivo and in vitro methods, Dietary iron absorption, apparent digestibility, and rat nutritional status of iron depleted and healthy rats were determined. In addition the metabolic energy of the six diets and rat growth index were calculated. Data analysis showed that, the in vivo protein digestibility index was lower than thai index of in vitro. Protein digestibility index of the anemic rats was higher than that index of healthy rats. The growth index of the healthy rats was higher than that index of the anemic rats. The rat growth index positively proportional to the dietary iron level, The DSF presence in diet caused growth index improvement. The WF+50g DSF+50mg iron diet improves protein digestibility and rat growth index.

The effect of vacuum time, restoration time, steam-cooking and storage at 4 °C on the iron content of vacuum-impregnated (VI) whole potato was evaluated. Whole potato tubers were immersed in a 0.4 g/100 g iron (ferric pyrophosphate) solution. Vacuum pressure of 1000 Pa was applied for 0–120 min, and atmospheric pressure restoration for 0–4 h. The result indicated that the iron content of VI potatoes increased with vacuum and restoration time; 1 h vacuum-treatment potatoes provided 6.4 times higher iron content compared to raw potatoes, and 3 h restoration time supplied 6.4 times higher iron content (>4.1 mg/100 g fr.wt.) compared to raw potatoes. Moreover, VI-cooked unpeeled or peeled potatoes had 6 times higher iron content than un-VI-cooked unpeeled or peeled potatoes. European daily potato consumption (260 g) of the VI-cooked unpeeled and peeled potatoes provided adult men with 93–104% and 67–90% of the recommended daily allowance (RDA) of iron, respectively. Also, the daily potato consumption of the unpeeled and peeled potatoes could supply adult women with 43–48% and 31–41% of the RDA, respectively. This study indicated that VI treatment of whole potato was useful for enriching the iron content. [ABSTRACT FROM AUTHOR]

The acidification of paddy fields was studied in Guizhou Province, China. Affected by acid mine drainage, the pH value of irrigation water was 2.9 with the concentrations of iron and aluminium above 40 mg/L. Based on the pH(H 2O) of topsoil, the paddy fields studied were classified spatially into three zones, the natural zone (pH value from 6.2 to 5.5), the acidified zone (pH value from 5.5 to 4.5), and the seriously acidified zone (pH value from 4.5 to 3.2), respectively. Comparing to the natural zone, the buffering processes for acidification of paddy soil were discussed by considering the changes of calcium, magnesium, potassium and aluminium in soils. The Ca, Mg and K were leached from the soil by the decomposition of carbonate and kaolinite. The leaching of Mg became less with the enrichment of iron in topsoil layer. When the soil pH was below 5.0, aluminium was leached from soil because of the dissolution of alumino silicate minerals. In addition, the hydrolysis of iron and aluminium in soil provided more protons to promote the soil acidification. Furthermore, the buffer capacity of paddy soil was discussed by the results of buffer experiment, based on which the pH buffer curve was drawn and the empirical formula for calculating the acidification rate was developed. Because pH buffer capacity of soil is about 2.78 cmol c/kg pH for the pH(H 2O) value above 5.0, it is estimated that only another 50 years are needed for the pH(H 2O) of the paddy soil decrease to 3.5 in the acidified zone if the acid water is used for irrigation continuously. [ABSTRACT FROM AUTHOR]

Abstract: Coastal organisms are often exposed to both iron enrichment and eutrophication. Trace elements transfer in coastal food webs are critical for marine life and therefore influence coastal ecosystem function and the global carbon cycle. However, how these exposures affect algal element uptake and the subsequent element transfer to marine copepods (Tigriopus japonicus) is unknown. Here we investigated the effects of nitrate addition and iron speciation (Fe (OH)3 or EDTA–Fe) on the biological uptake of Cu, Zn, and Se under phosphate and iron enrichment, using Thalassiosira weissflogii, Skeletonema costatum, and Chlorella vulgaris as model marine algae. Algal element adsorption/absorption generally increased with increasing macronutrient concentrations. Algal element assimilation efficiencies depended on iron speciation and marine algae species. Element assimilation efficiencies of copepods were significantly correlated to the intracellular element concentrations in algal cells. Element uptake and transfer were controlled by eutrophication, iron speciation, and algal species in coastal food webs. [Copyright &y& Elsevier]

Abstract: Significant effort has been invested in understanding the role of iron in marine ecosystems over the past few decades. What began as shipboard amendment experiments quickly grew into a succession of in situ, mesoscale ocean iron fertilization (OIF) experiments carried out in all three high nutrient low chlorophyll (HNLC) regions of the world ocean. Dedicated process studies have also looked at regions of the ocean that are seasonally exposed to iron-replete conditions as natural OIF experiments. However, one problem common to many OIF experiments is determination of biological response beyond the duration of the experiment (typically<1 month). Satellite-derived products have been used to address this shortcoming with some success, but thus far, have been limited snapshots of a single parameter, chlorophyll. Here, we investigate phytoplankton responses to OIF in both purposeful and naturally iron enriched systems using estimates of chlorophyll (Chl), phytoplankton carbon biomass (Cphyto), their ratio (Chl:Cphyto) and two fluorescence indices, fluorescence per unit chlorophyll (FLH:Chl) and the chlorophyll fluorescence efficiency (ϕ f ). These quantities allow partitioning of the biological response to OIF into that due to changes in biomass and that due to phytoplankton physiology. We find that relative increases in Chl (∼10–20x) following OIF far exceed increases in Cphyto (<4–5x), suggesting that a significant fraction of the observed Chl increase is associated with physiological adjustment to increased growth rates, photoacclimation, and floristic shifts in the phytoplankton community. Further, a consistent pattern of decreased satellite fluorescence efficiency (FLH:Chl or ϕ f ) following OIF is observed that is in agreement with current understanding of phytoplankton physiological responses to relief from iron stress. The current study extends our ability to retrieve phytoplankton physiology from space-based sensors, strengthens the link between satellite fluorescence and iron availability, and shows that satellite ocean color analyses provide a unique tool for monitoring OIF experiments. [Copyright &y& Elsevier]

Abstract: On-deck CO2-Fe-manipulated incubation experiments were conducted using surface seawater collected from the Western Subarctic Gyre of the NW Pacific in the summer of 2008 to elucidate the impacts of ocean acidification and Fe enrichment on the abundance and community composition of phytoplankton and eubacteria in the study area. During the incubation, excluding the initial period, the mean partial pressures of CO2 in non-Fe-added bottles were 230, 419, 843, and 1124μatm, whereas those in Fe-added treatments were 152, 394, 791, and 1008μatm. Changes in the abundance and community composition of phytoplankton were estimated using HPLC pigment signatures with the program CHEMTAX and flow cytometry. A DGGE fingerprint technique targeting 16S rRNA gene fragments was also used to estimate changes in eubacterial phylotypes during incubation. The Fe addition induced diatom blooms, and subsequently stimulated the growth of heterotrophic bacteria such as Roseobacter, Phaeobacter, and Alteromonas in the post-bloom phase. In both the Fe-limited and Fe-replete treatments, concentrations of 19′-hexanoyloxyfucoxanthin, a haptophyte marker, and the cell abundance of coccolithophores decreased at higher CO2 levels (750 and 1000ppm), whereas diatoms exhibited little response to the changes in CO2 availability. The abundances of Synechococcus and small eukaryotic phytoplankton (<10μm) increased at the higher CO2 levels. DGGE band positions revealed that Methylobacterium of Alphaproteobacteria occurred solely at lower CO2 levels (180 and 380ppm) during the post-bloom phase. These results suggest that increases in CO2 level could affect not only the community composition of phytoplankton but also that of eubacteria. As these microorganisms play critical roles in the biological carbon pump and microbial loop, our results indicate that the progression of ocean acidification can alter the biogeochemical processes in the study area. [Copyright &y& Elsevier]

Abstract: We studied the microbial food web in the upper 100m of the water column in iron-limited sub-Antarctic HNLC waters south-east of New Zealand in the SAGE experiment in 2004, with focus on bacterioplankton. Samples were collected daily from inside and outside the iron enriched patch. Short term enrichment experiments were conducted on board in 4L polycarbonate bottles with water outside the iron enriched patch to study single and combined effects of micronutrient additions on microbial food web. Low bacterial growth was recorded in the study area with community turnover times of 50h or more during the study period. Measurements of bacterial standing stocks and production rates in the study show minor responses to the large scale iron enrichment, with increase in rates and stocks after the first enrichment and at the end of the study period after the third iron enrichment when solar radiation increased and wind mixing decreased. The average daily bacterial production rates were 31.5 and 33.7mgCm−2 d−1 for the OUT and IN stations, respectively; thus overall there was not a significant difference between the control and the iron-enriched patch. In the bottle experiments bacterial thymidine incorporation showed responses to single iron and silicic acid enrichments and a major growth response to the combined iron and sucrose enrichments. Phytoplankton chlorophyll-a showed clear stimulation by single additions of iron and silicic acid and silicic acid enhanced the iron impact. Cobalt additions had no effect on bacteria growth and a negative effect on phytoplankton growth. Low bacterial in situ growth rates and the enrichment experiments suggest that bacteria are co-limited by iron and carbon, and that bacterial iron uptake is dependent on carbon supply by the food web. With the high iron quota (μmolFemolC−1) bacteria may scavenge considerable amounts of the excess iron, and thus influence the relative importance of the microbial food web as a carbon sink. [Copyright &y& Elsevier]

Iron fertilization of the Southern Ocean is believed to counter the increasing CO2 concentration in the atmosphere and the consequent global warming. Though a number of large scale iron enrichment experiments have been done in the recent past in different parts of the world ocean, little effort has been made to understand the effect of iron enrichment on nitrogen uptake rates and ∫-ratios. Here we assess the effect of iron addition on N-uptake rates and ∫-ratio in the Indian sector of the Southern Ocean. This study shows, in contrast to the earlier belief, that iron addition enhances not only nitrate uptake (∼3×) but it causes a significant increase in ammonium (∼2×) and urea (∼3×) uptakes as well. Also, since iron enrichment caused significant increase in the uptake of all N-substrates, its effect on ∫-ratio was insignificant. [ABSTRACT FROM AUTHOR]

Abstract: Little is known about the effects of iron enrichment in high-nitrate low-chlorophyll (HNLC) waters on the community composition of heterotrophic bacteria, which are crucial to nutrient recycling and microbial food webs. Using denaturing gradient gel electrophoresis (DGGE) of 16S rDNA fragments, we investigated the heterotrophic eubacterial community composition in surface waters during an in situ iron-enrichment experiment (SEEDS-II) in the western subarctic Pacific in the summer of 2004. DGGE fingerprints representing the community composition of eubacteria differed inside and outside the iron-enriched patch. Sequencing of DGGE bands revealed that at least five phylotypes of α-proteobacteria including Roseobacter, Cytophaga-Flavobacteria-Bacteroides (CFB), γ-proteobacteria, and Actinobacteria occurred in almost all samples from the iron-enriched patch. Diatoms did not bloom during SEEDS-II, but the eubacterial composition in the iron-enriched patch was similar to that in diatom blooms observed previously. Although dissolved organic carbon (DOC) accumulation was not detected in surface waters during SEEDS-II, growth of the Roseobacter clade might have been particularly stimulated after iron additions. Two identified phylotypes of CFB were closely related to the genus Saprospira, whose algicidal activity might degrade the phytoplankton assemblages increased by iron enrichment. These results suggest that the responses of heterotrophic bacteria to iron enrichment could differ among phylotypes during SEEDS-II. [Copyright &y& Elsevier]

The available literature on whether or not foliar iron (Fe)-containing solutions can be one of the sustainable and low-cost strategies to increase Fe concentration in edible portions of staple food crops consisted of a few previous studies of Fe in plants, and mainly focused on Fe-deficiency remedies. Our experiment was carried out to examine the effects of foliar Fe-containing solutions on Fe enrichment and on the nutritional, cooking, and eating qualities of polished rice of the japonica 'Bing 98110' planted on a powdery loam soil under pot conditions. The results showed that Fe concentration in polished rice could be enriched with foliar Fe(II)-amino acids [the main formulation was the complex of 0.1% (w/v) FeSO4•7H2O and 0.4% (w/v) compound amino acids, 18.6% N] application. Compared with the control, Fe concentration increased significantly, by 88.0%. Meanwhile, the positive effects on Zn concentration and protein and amino acid content improvement were found with boric acid (H3BO3, B) added to Fe(II)-amino acids foliar application. In detail, Zn concentration significantly increased (19.6%), and protein and lysine were increased significantly by 30.1 and 35.1%, respectively. Also the cooking and eating qualities were improved with foliar Fe(II)-amino acids and B compound spray. [ABSTRACT FROM AUTHOR]

Abstract: Size-segregated aerosol samples (PM2.5 and PM10) were collected during Jan–Dec-2007 from a high-altitude site located in a semi-arid region (Mt. Abu, 24.6 °N, 72.7 °E, 1680 m asl) in order to asses the temporal variability in the abundance of atmospheric mineral dust and its elemental composition over western India. The mass concentrations of fine (PM2.5) and coarse (PM10–2.5) mode aerosols varied from 1.6 to 46.1 and 2.3 to 102 μg m−3 respectively over the annual seasonal cycle; with dominant and uniform contribution of mineral dust (60–80%) in the coarse mode relative to large temporal variability (11–75%) observed in the fine mode. The coarse mass fraction shows a characteristic increase with the wind speed during summer months (Mar to Jun); whereas fine aerosol mass and its elemental composition exhibit conspicuous temporal pattern associated with north-easterlies during wintertime (Oct–Feb). The Fe/Al weight ratio in PM2.5 ranges from 0.5 to 1.0 during winter months. The relative enrichment of Fe in fine mode, compared to the crustal ratio of 0.44, is attributed to the down-wind advective transport of combustion products derived from large-scale biomass burning, industrial and automobile emission sources located in the Indo-Gangetic Plain (northern India). In contrast, Ca/Al and Mg/Al weight ratios show relative enrichment of Ca and Mg in the coarse mode; indicating their dominant contribution from carbonate minerals. This has implication to efficient neutralization of atmospheric acidic species (SO4 2− and NO3 −) by mineral dust over western India. [Copyright &y& Elsevier]

There is a fundamental conflict between the suggestion that the iron content of Skaergaard liquids increases during Fe–Ti oxide fractionation and the observation that at the same time oxygen fugacity ( $$ f_{{\text{O}_{\text{2}}}} $$) drops by two log-units below the fayalite-magnetite-quartz oxygen buffer (FMQ). A new petrographic study of average Skaergaard gabbros shows that the total modal content of Fe–Ti oxides is about 22% in the early LZc and markedly decreases to below 5% in the UZc. Forward modeling based on these modal constraints, as well as experimental results on Skaergaard-related dikes, predicts that fractionation of troctolitic LZa gabbros drives the derivative liquid towards a high-iron content. Strong iron enrichment continues, together with a small decline in silica, during LZb crystallization due to the appearance of augite as a fractionating phase. The fractionation of Fe–Ti oxides in the LZc initially suppresses iron enrichment and reverses the silica trend to one of slight enrichment. However, continued evolution into the UZ produces liquids with maximum UZc FeO* content of 23–25 wt.% and SiO2 content of 53 wt.% (FeO* is total iron as FeO). The maximum in FeO* is dependent on several factors of which the Fe–Ti oxide mode has the strongest effect. The $$ f_{{\text{O}_{\text{2}}}} $$ during crystallization of the LZc is widely thought to have been at, or slightly below, the fayalite-magnetite-quartz oxygen buffer (FMQ). Under closed system evolution, incorporation of ferric iron into augite during formation of the LZb restricts the increase in $$ f_{{\text{O}_{\text{2}}}} $$ to about 0.1 log-units above FMQ (=0.1 ΔFMQ). Likewise, crystallization of the LZc through the UZa, involving Fe–Ti oxide minerals, leads to a decline in $$ f_{{\text{O}_{\text{2}}}} $$ of less than 0.1 ΔFMQ. Crystallization of the UZb-c gabbros results in oxidation to a maximum of 0.5 ΔFMQ. This behavior can account for the iron-rich character of the UZ gabbros, as well as, the low modal content of Fe–Ti oxides. Thus, evolved Skaergaard liquids are high in iron and contain a modest amount of SiO2. Our modeling result do not account for a strong drop in $$ f_{{\text{O}_{\text{2}}}} $$ through the layered series. Such a drop would require an unacceptably high proportion of Fe–Ti oxides and high-magnetite content in the fractionating assemblage. [ABSTRACT FROM AUTHOR]

Abstract: The Lagrangian Southern Ocean Iron Release Experiment (SOIREE) allowed study of a gradually evolving iron-mediated phytoplankton bloom in water labelled with the inert tracer sulfur hexafluoride, SF6. This article describes a pelagic carbon budget for the mixed layer in SOIREE and assesses the extent to which closure of the budget is achieved. Net community production (NCP) converted 837mmolm−2 of inorganic carbon to organic carbon in 12.0d after the first iron addition. A large fraction (41%) of NCP remained as particulate organic carbon in the mixed layer of the iron-enriched patch, while 23% was lost by horizontal dispersion and 0–29% was exported. The closure of the carbon budget is hampered by the lack of measurements of dissolved organic carbon (DOC), by a major uncertainty in carbon export, and by use of empirical conversion factors in estimates of carbon biomass and metabolic rates. Lagrangian carbon-budget studies may be improved by direct measurement of all major carbon parameters and conversion factors. Carbon cycling in the SOIREE bloom resembled that in ‘natural’ algal blooms in the open Southern Ocean in some respects, but not in all. Daily NCP in the SOIREE bloom (70mmolm−2 d−1) was higher than in natural blooms, partly because other studies did not account for horizontal dispersion, were for longer periods or included less productive areas. The build-up of POC stock and carbon export as a fraction of NCP in SOIREE were in the lower range of observations elsewhere. [Copyright &y& Elsevier]

Abstract: Numerical modeling experiments were conducted to examine the reasons for observed changes in the silicic acid ([Si(OH)4]) to nitrate drawdown ratio after the onset of algal iron stress during SERIES. During phytoplankton blooms and immediately after them, cells encounter a range of iron stress (between iron-replete and iron-deplete) and therefore show a range of growth rates. For these reasons, the potential influence of phytoplankton growth rate, under conditions of algal iron stress, on silicic acid and nitrate depletion were investigated in numerical experiments by altering the timing of a shift in the [Si(OH)4]: uptake ratio. These simulations suggested that the continued growth of iron-stressed phytoplankton at sub-maximum rates, with an elevated [Si(OH)4]: uptake ratio, induced depletion of silicic acid in the surface water and resulted in simultaneous limitation of growth by both iron and silicic-acid supply. Therefore, bottom-up control played an important role in terminating the phytoplankton bloom in SERIES. In the model simulations, the enhancement of diatom silicification due to increased rates of biomass-normalized silicic-acid uptake, led to increases in the export flux of opal after the onset of algal iron-stress and, consequently, it stimulated the silica pump. The regulation of both the [Si(OH)4]: uptake ratio and the growth rate of phytoplankton by iron supply are important factors that determine the relative consumption of silicic acid and nitrate upon iron stress, although the potential influence of a floristic shift in the diatom assemblage cannot be ruled out. These findings offer insights into the impact of iron fertilization, both artificial and natural, on the biogeochemical cycling of nutrients in high-nitrate, low-chlorophyll waters. [Copyright &y& Elsevier]

Abstract: A mesoscale iron-fertilization experiment was carried out in the eastern subarctic Pacific during summer 2002. The iron patch was traced for 26 days after the enrichment, and the abundance and behavior of mesozooplankton was compared with those outside of the patch during the first half of the experiment (days 2–18) by Sastri and Dower [2006. Mesozooplankton community response during the SERIES iron enrichment experiment in the subarctic NE Pacific. Deep-Sea Research Part II.) and during the post-enrichment diatom bloom and its period of decline (days 15–26; this paper). The surface chlorophyll-a concentration in the patch was high between days 15 and 17 (6mgm−3) and decreased to 1.4mgm−3 at the end of the observation. Dominant zooplankton species in the upper 200m were copepods: Eucalanus bungii, Pseudocalanus spp., Neocalanus plumchrus, N. cristatus, and Metridia pacifica. Species composition did not change significantly in the patch over the observation period. However, shallower distribution depths of E. bungii, N. cristatus and M. pacifica were observed in the patch during and after the diatom bloom. Especially, E. bungii was mainly distributed in the subsurface layer outside of the patch, but it was mainly in the surface mixed layer inside the patch, where it also had an enhanced development rate and increased biomass. We also propose the accumulation mechanism of zooplankton in the patch due to the upward immigration. Moreover, the abundance of the first copepodite stage of E. bungii and calyptopis larvae of euphausiids increased several fold in the patch compared to the densities outside the patch. The increases in both species are considered to be due to lowered mortality during the egg and naupliar stages, which was caused by lowered relative importance of eggs and nauplii in the diets of the suspension-feeding omnivores in the patch due to increased diatom abundance during the diatom bloom. Gut-pigment contents of dominant copepods in the patch increased 6–8 times, and the maximum values were observed during the bloom peak. The grazing impact on phytoplankton was low during the bloom period, but increased in the declining period of the diatom bloom. [Copyright &y& Elsevier]

Abstract: We report the response in the natural abundance of the stable isotopes of nitrogen (δ 15N) during the Fe-enrichment experiment SERIES (Subarctic Ecosystem Response to Iron Enrichment Study) in the NE Pacific. Samples were collected for isotope analysis of nitrate, particulate material (including size fractionated samples), and particles trapped in the water column from beneath the Fe-enriched patch. In all sample types, δ 15N changed in response to increased phytoplankton productivity after the Fe enrichment. The nitrate concentration and δ 15N of nitrate were inversely related, the result of the opposing effects of isotope fractionation during nitrate assimilation and the addition of new nitrate by periodic mixing of water from outside the Fe patch. During the growth period a decrease in the difference of the δ 15N of particulate nitrogen and nitrate occurred that was attributed to physical mixing, shifts in growth from regenerated nitrogen sources to nitrate, and the change in the community assemblage from<5-μm phytoplankton cells to a larger assemblage dominated by diatoms. The surface-tethered sediment trap δ 15N samples indicate that the nitrate isotope fractionation signal in surface waters was not transported below the permanent mixed layer until the end of the phytoplankton growth period, and therefore only the highest values associated with the isotope fractionation process were recorded in the sinking material from the patch. An important conclusion from this study is that mesoscale physical mixing effects and nitrogen remineralization can reduce the expression of isotope fractionation during phytoplankton growth, explaining why the high fractionation values measured in laboratory studies are not commonly observed in the natural environment. [Copyright &y& Elsevier]

Abstract: In November 2000, a second iron enrichment experiment (EisenEx) was carried out in the Southern Ocean. Iron was added on the 8th of November in the centre of an eddy at 21°E, 48°S. During the cruise, the carbonate parameters dissolved inorganic carbon (DIC), fugacity of CO2 (fCO2) and pH on the hydrogen ion scale (pHT) were determined from water samples from both inside and outside the iron fertilized patch. Before the start of the experiment, the surface properties of the eddy were quite uniform with respect to the carbonate system and representative of the High Nutrient Low Chlorophyll (HNLC) regions in the Southern Ocean. The response of the carbon dioxide system to the initial ≈4 nM iron (Fe) infusion and to two subsequent reinfusions at 15 m depth was measured every day during the study. The changes in the carbon dioxide system and major nutrients were strongly influenced by the meteorological conditions with a rapid succession of calm, often sunny spells and storm force winds during the 21 days of experiment. Twenty days after the first Fe-infusion, the maximum changes of the carbonate parameters in surface waters of the patch relative to outside patch were −15 μmol kg−1 in DIC, −23 μatm in fCO2, +0.033 units in pHT, −1.61 μM in nitrate and −0.16 μM in phosphate in a mixed layer of 80 m depth. In addition to the daily measurements, several transects were made across the patch that showed a response of the carbonate system to the influence of iron, concomitant with a response in nutrients and chlorophyll. The relative changes in dissolved inorganic carbon to nutrient concentrations inside the patch during the experiment give N/P=12, C/P=82, C/N=5.9, C/Si=2.9 and N/Si=0.5. The effect of the influx of atmospheric CO2 on the DIC inventory was small with values between 0.05 and 0.10 μmol kg−1 day−1, and did not significantly affect these ratios. Although the observed change in DIC in the Fe-enriched surface waters was lower than in the previous Fe-enrichment experiments, the equivalent biological C-uptake of 1.08×109 mol C across the patch after 20 days was significant due to the large horizontal dispersion of the patch. The ratio of biological carbon uptake to Fe added (Cbiological uptake/Feadded) was 2.5×104 mol mol−1. [Copyright &y& Elsevier]

Abstract: Dynamics of transparent exopolymer particles (TEP) was studied during the first in situ iron-enrichment experiment conducted in the western subarctic Pacific in July–August 2001, with the goal of evaluating the contribution of TEP to vertical flux as a result of increased primary production following iron enrichment in open ocean ecosystems. Subsequent to the enhancement of phytoplankton production, we observed increase in TEP concentration in the surface layer and sedimentation of organic matter beneath it. Vertical profiles of TEP, chlorophyll a (Chl a) and particulate organic carbon (POC) were obtained from six depths between 5 and 70m, from a station each located inside and outside the enriched patch. TEP and total mass flux were estimated from the floating sediment traps deployed at 200m depth. Chl a and TEP concentrations outside the patch varied from 0.2 to 1.9μgL−1 and 40–60μgXGequiv.L−1, respectively. Inside the patch, Chl a increased drastically from day 7 reaching the peak of 19.2μgL−1 on day 13, which coincided with the TEP peak of 189μgXGequiv.L−1. TEP flux in the sediment trap increased from 41 to 88mgXGequiv.m−2 d−1, with 8–14% contribution of TEP to total mass flux. This forms the basic data set on ambient concentrations of TEP in the western subarctic Pacific, and evaluation of the effect of iron enrichment on TEP. [Copyright &y& Elsevier]

Abstract: Phytoplankton species composition was analyzed inside and outside of the iron-enriched patch during the SEEDS experiment. Before the iron-enrichment, the phytoplankton community consisted of similar proportions of pico-, nano- and micro-sized phytoplankton, and the micro-phytoplankton was dominated by the pennate diatom Pseudo-nitzschia turgidula. Although all the diatoms, except the nano-sized Fragilariopsis sp., increased during the two weeks of the observation period, the flora in the patch dramatically changed with the increase of phytoplankton biomass to a centric diatom-dominated community. Neritic diatoms, especially Chaetoceros debilis, showed higher growth rates than other diatoms, without any delay in the initiation of growth after the enrichment, and accounted for 90% of the micro-phytoplankton after day 9. In contrast, the oceanic diatoms showed distinct delays in the initiation of growth. We conclude that the responses of the diatoms to the manipulation of iron concentration were different by species, and the fast and intensive response of the phytoplankton to iron-enrichment resulted from the presence of a small amount of neritic diatoms at the study site. The important factors that determine the dominant species in the bloom are the potential growth rates under an iron-replete condition and the growth lag. Abundant species in the patch are widely distributed in the North Pacific and their relative contributions in the Oyashio area and at Stn KNOT are high from spring to summer. However, a characteristic difference of species composition between the SEEDS bloom and natural blooms was the lack of Thalassiosira and Coscinodiscus species in the patch, which usually account for a major part of the phytoplankton community under blooming conditions in the western North Pacific. [Copyright &y& Elsevier]

[Display omitted] • The contribution of three stresses to OC's attrition is quantitatively analyzed. • The attrition type of OCs under different conditions are determined. • Phase separation reduces the mechanical strength of OC. • The crack propagation process on the surface of OC is illustrated. • Crack propagation and Fe-rich effect result in OC fragmentation. Chemical looping combustion (CLC) is one of the most promising CO 2 capture technologies, where oxygen carriers (OCs) circulate between a fuel reactor and an air reactor and is mainly responsible for providing lattice oxygen and heat to the fuel reactor. The lifetime of OC is an important parameter that has a great effect on CLC's economic performance. Attrition is one of the most crucial reasons that shortens OC's lifetime. In this study, attrition behavior of an iron-based OC in relatively long-period experiments was carried out in a fluidized bed reactor, and cold attrition experiment (CAE), hot attrition experiment (HAE) and reactive attrition experiment (RAE) were tested to quantify the contribution of mechanical stress, thermal stress and chemical stress to OC's attrition. Morphology of cracks, surface elements distribution and crystal phase of OC in different stages during cyclic reactions were studied in detail, and the attrition mechanism of OC is therefore proposed. For COs produced by powder mixing and sintering, results show that the contribution of chemical stress to the attrition of OC is a dynamic increase process, and it completely dominates the attrition after the 40th cycle. The attrition rate of OC under different conditions follows RAE > HAE > CAE and attrition type in CAE and HAE mainly follows surface abrasion, while the attrition in RAE is a mixed attrition mechanism dominated by bulk fracture. Analysis indicates crack propagation and the Fe-rich effect caused by the continuous oxidation–reduction reaction together lead to comminution of OC. [ABSTRACT FROM AUTHOR]

The effect of iron enrichment on algal growth and photosynthesis was investigated using natural assemblages of Lake Erie phytoplankton and axenic cultures of Anabaena, Scenedesmus and Selenastrum. Cell yield and photosynthesis were frequently inhibited in the presence of unchelated iron over the range of 3.6 to 55.7 lam iron as FeCl[sub5] In lake water and in a defined medium with low nutrient concentrations, the degree of inhibition by iron could be reduced by chelating the iron with EDTA or by enriching the cultures with phosphorus. Chemical analyses revealed that the EDTA effectively reduced the ability of the ferric iron to remove soluble phosphorus from the media. EDTA was also observed to reduce rather than enhance iron uptake by axenic cultures of A. flos-aquae. These data support the hypothesis that additions of EDTA to low-nutrient media may sense lo stimulate algal growth in the presence of iron by preventing the iron from altering extracellular concentrations of soluble ions essential for algal metabolism, In medium with high nutrient concentrations, the soluble phosphorus concentration was not appreciably altered by either EDTA-chelated or unchelated iron enrichment (0.9 to 53.7 μM). Instead, the observed enhancement of cell yield by EDTA-chelated iron in nutrient-rich media appeared to be due to the direct effect of iron on intracellular metabolic processes. [ABSTRACT FROM AUTHOR]

Because processes such as fractional crystallization and crystallization under conditions closed to oxygen are difficult to simulate in the laboratory there is a need for quantitative models of magma crystallization behaviour. Comparison of experimental data on an iron-rich basaltic composition with predictions of the MELTS free energy minimization algorithm shows that although liquidus temperatures and silicate mineral equilibria are predicted relatively well, the saturation of Fe–Ti oxides is not We have used the same experimental data to construct an alternative crystallization model based on known equilibrium phase relations, mineral–melt partitioning of major elements, and mass balance constraints. The model is used to explore the consequences of equilibrium and fractional crystallization in systems open and closed to oxygen. Liquid lines of descent for perfect equilibrium and perfect fractional crystallization are predicted to be very similar. In a system open to oxygen the model predicts that magnetite saturation leads to strongly decreasing iron and increasing silica contents of residual liquids, whereas systems closed to oxygen crystallize less abundant magnetite, leading to a less pronounced iron depletion in the liquid. Predicted bulk solid compositions and variations of fo2, with falling temperature agree well with those observed or inferred from the cumulates of the Skaergaard intrusion, but none of the predicted liquid lines of descent are consistent with the extreme iron enrichment proposed for this intrusion based on mass balance calculations. Compositional factors such as water and phosphorus are not thought to be the source of the discrepancy as the cumulates of the Basistoppen sill (which closely resemble those of Skaergaard) may be used to calculate a liquid line of descent in agreement with that predicted by the model for fractional crystallization closed to oxygen. A comparison of the predicted T-fo2, paths and liquid lines of descent with those inferred from natural systems suggests that volcanic centres such as Iceland and Hawaii evolve under conditions open to oxygen, whereas evidence from plutonic environments (e.g. Skaergaard and Kiglapait layered intrusions) suggests that they evolved under conditions more closed to oxygen. The compositional evolution of the melt phase in volcanic and plutonic systems may therefore be different, although the results of this study suggest that magnetite saturation will limit Fe enrichment in all environments to <20wt% FeO*, consistent with enrichments reported for volcanic glasses. [ABSTRACT FROM AUTHOR]

Surface dissolved dimethylsulfide (DMS) and depth-integrated dimethylsulfoniopropionate (DMSP) measurements were made from March to April 2004 during the SOLAS Air–Sea Gas Exchange Experiment (SAGE), a multiple iron enrichment experiment in subantarctic waters SE of New Zealand. During the first two iron enrichments, chl a and DMS production were constrained, but during the third enrichment, large pulses of DMS occurred in the fertilised IN patch, compared with the unfertilised OUT patch. During the third and fourth iron infusions, total chl a concentrations doubled from 0.52 to 1.02 µg/L. Hapto8s and prasinophytes accounted for 50%, and 20%, respectively, of total chl a. The large pulses of DMS during the third iron enrichment occurred during high dissolved DMSP concentrations and wind strength; changes in dinoflagellate, haptophyte, and cyanobacteria biomass; and increased microzooplankton grazing that exerted a top down control on phytoplankton production. A further fourth iron enrichment did cause surface waters to increase in DMS, but the effect was not as great as that recorded in the third enrichment. Differences in the biological response between SAGE and several other iron enrichment experiments were concluded to reflect microzooplankton grazing activities and the microbial loop dominance, resulting from mixing of the MLD during storm activity and high winds during iron enrichment. [ABSTRACT FROM AUTHOR]