Molecular-scale Study of Cr(VI) Adsorption onto Lepidocrocite Facets by EXAFS, In Situ ATR-FTIR, Theoretical Frequency Calculations and DFT+U Techniques

Lepidocrocite, as a ubiquitous iron mineral, is widely detected as different morphologies in natural environments, controlling the mobility and availability of heavy metal ions (HMIs). These different morphologies of lepidocrocite...

PENGARUH PEMBERIAN MINUMAN KURMA TERHADAP PENINGKATAN HEMOGLOBIN PADA IBU HAMIL PENDERITA ANEMIA DI RUMAH SAKIT GRANDMED LUBUK PAKAM

Anemia is a disease associated with pregnant women. The incidence of anemia due to iron mineral deficiency. This studi aims to determine the effect of giving dates drink to increasing haemoglobin levels in pregnant women with anemia in Rumah Sakit Grandmed Lubuk Pakam. This research method is quasi experiment with pre and posttest design. The population in this study is pregnant women with anemia in Rumah Sakit Grandmed Lubuk Pakam. The sample is 38 people consisting. In the treatment group was given intervention dates drink as much as 240 ml every day for 10 days. From the result of this research the majority of haemoglobin levels increased.The average haemoglobin levels after giving dates drink of 10 mg/dl. The result of the analysis with T-test was obtained p Value 0,000, it can concluded that there is the effect of determine the effect of giving dates drink to increasing haemoglobin levels in pregnant women with anemia.

Response of methanogen communities to the elevation of cathode potentials in bioelectrochemical reactors amended with magnetite

Electromethanogenesis refers to the process where methanogens utilize current for the reduction of CO 2 to CH 4 . Setting low cathode potentials is essential for this process. In this study, we test if magnetite, an iron oxide mineral widespread in the environment, can facilitate the adaption of methanogen communities to the elevation of cathode potentials in electrochemical reactors. Two-chamber electrochemical reactors were constructed with inoculants obtained from paddy field soil. We elevated cathode potentials stepwise from the initial -0.6 V vs the standard hydrogen electrode (SHE) to -0.5 V and then to -0.4 V over the 130 days acclimation. Only weak current consumption and CH 4 production were observed in the bioreactors without magnetite. But significant current consumption and CH 4 production were recorded in the magnetite bioreactors. The robustness of electro-activity of the magnetite bioreactors was not affected by the elevation of cathode potentials from -0.6 V to -0.4 V. But, the current consumption and CH 4 production were halted in the bioreactors without magnetite when the cathode potentials were elevated to -0.4 V. Methanogens related to Methanospirillum were enriched on the cathode surfaces of magnetite bioreactors at -0.4 V, while Methanosarcina relatively dominated in the bioreactors without magnetite. Methanobacterium also increased in the magnetite bioreactors but stayed off electrodes at -0.4 V. Apparently, the magnetite greatly facilitates the development of biocathodes, and it appears that with the aid of magnetite, Methanospirillum spp. can adapt to the high cathode potentials performing efficient electromethanogenesis. IMPORTANCE Converting CO 2 to CH 4 through bioelectrochemistry is a promising approach to the development of green energy biotechnology. This process however requires low cathode potentials, which takes cost. In this study, we test if magnetite, a conductive iron mineral, can facilitate the adaption of methanogens to the elevation of cathode potentials. In the two-chamber reactors constructed by using inoculants obtained from paddy field soil, biocathodes were firmly developed in the presence of magnetite, whereas only weak activities in CH 4 production and current consumption were observed in the bioreactors without magnetite. The elevation of cathode potentials did not affect the robustness of electro-activity of the magnetite bioreactors over the 130 days acclimation. Methanospirillum were identified as the key methanogens associated with the cathode surfaces during the operation at high potentials. The findings reported in this study shed new light on the adaption of methanogen communities to the elevated cathode potentials in the presence of magnetite.

Pyrite Framboid Formation Chemistry

Pyrite forms mainly through two routes: (1) the reaction between FeS species and polysulfides, and (2) the reaction of FeS species and H2S. Both of these reactions produce framboidal pyrite, and the mechanisms have been confirmed both kinetically and through the use of isotopic tracers. Aqueous Fe2+ does not appear to react directly with aqueous polysulfide species to produce pyrite, and the S-S bond in aqueous S2(-II) is normally split by aqueous Fe2+ to produce aqueous FeS and sulfur. The FeS moiety involved in pyrite formation may be provided by aqueous FeS or =FeS groups on solid surfaces. The reaction with surface =FeS occurs with any iron mineral in a sulfidic environment, including the relatively scarce iron sulfide minerals, mackinawite and greigite, nanoparticulate FeS, and pyrite itself. The reaction with surface =FeS sites on pyrite is a major route for pyrite crystal growth. The extreme insolubility of pyrite is one of the fundamental reasons for its particular involvement in framboid formation as well as for the ubiquity of framboids.

Microbial iron(III) reduction during palsa collapse promotes greenhouse gas emissions before complete permafrost thaw

Reactive iron (Fe) minerals can preserve organic carbon (OC) in soils overlying intact permafrost. With permafrost thaw, reductive dissolution of iron minerals releases Fe and OC into the porewater, potentially increasing the bioavailability of OC for microbial decomposition. However, the stability of this so-called rusty carbon sink, the microbial community driving mineral dissolution, the identity of the iron-associated carbon and the resulting impact on greenhouse gas emissions are unknown. We examined palsa hillslopes, gradients from intact permafrost-supported palsa to semi-wet partially-thawed bog in a permafrost peatland in Abisko (Sweden). Using high-resolution mass spectrometry, we found that Fe-bound OC in intact palsa is comprised of loosely bound more aliphatic and strongly-bound more aromatic species. Iron mineral dissolution by both fermentative and dissimilatory Fe(III) reduction releases Fe-bound OC along the palsa hillslopes, before complete permafrost thaw. The increasing bioavailability of dissolved OC (DOC) leads to its further decomposition, demonstrated by an increasing nominal oxidation state of carbon (NOSC) and a peak in bioavailable acetate (61.7±42.6 mg C/L) at the collapsing palsa front. The aqueous Fe2+ released is partially re-oxidized by Fe(II)-oxidizing bacteria but cannot prevent the overall loss of the rusty carbon sink with palsa collapse. The increasing relative abundance and activity of Fe(III)-reducers is accompanied by an increasing abundance of methanogens and a peak in methane (CH4) emissions at the collapsing front. Our data suggest that the loss of the rusty carbon sink directly contributes to carbon dioxide (CO2) production by Fe(III) reduction coupled to OC oxidation and indirectly to CH4 emission by promoting methanogenesis even before complete permafrost thaw.

Microbial iron(III) reduction during palsa collapse promotes greenhouse gas emissions before complete permafrost thaw

Reactive iron (Fe) minerals can preserve organic carbon (OC) in soils overlying intact permafrost. With permafrost thaw, reductive dissolution of iron minerals releases Fe and OC into the porewater, potentially increasing the bioavailability of OC for microbial decomposition. However, the stability of this so-called rusty carbon sink, the microbial community driving mineral dissolution, the identity of the iron-associated carbon and the resulting impact on greenhouse gas emissions are unknown. We examined palsa hillslopes, gradients from intact permafrost-supported palsa to semi-wet partially-thawed bog in a permafrost peatland in Abisko (Sweden). Using high-resolution mass spectrometry, we found that Fe-bound OC in intact palsa is comprised of loosely bound more aliphatic and strongly-bound more aromatic species. Iron mineral dissolution by both fermentative and dissimilatory Fe(III) reduction releases Fe-bound OC along the palsa hillslopes, before complete permafrost thaw. The increasing bioavailability of dissolved OC (DOC) leads to its further decomposition, demonstrated by an increasing nominal oxidation state of carbon (NOSC) and a peak in bioavailable acetate (61.7±42.6 mg C/L) at the collapsing palsa front. The aqueous Fe2+ released is partially re-oxidized by Fe(II)-oxidizing bacteria but cannot prevent the overall loss of the rusty carbon sink with palsa collapse. The increasing relative abundance and activity of Fe(III)-reducers is accompanied by an increasing abundance of methanogens and a peak in methane (CH4) emissions at the collapsing front. Our data suggest that the loss of the rusty carbon sink directly contributes to carbon dioxide (CO2) production by Fe(III) reduction coupled to OC oxidation and indirectly to CH4 emission by promoting methanogenesis even before complete permafrost thaw.