Particulate organic-matter: a comparison of methods for its determination and its role as an indicator of soil quality for some soils in the province of Chubut

La materia orgánica particulada (MOP) es un componente dinámico del suelo, que responde selectiva y rápidamente a los cambios de manejo y distintos tipos de disturbios. El objetivo de este estudio fue comparar dos técnicas de determinación de MOP en distintos suelos y evaluar el potencial de esta variable como indicadora de calidad de los mismos. Se estudiaron tres sitios ecológicos de la provincia del Chubut con distinto manejo o afectados por distintos disturbios: Media Luna Clausura (MLC), Media Luna Pastoreo (MLP ), Puerto Madryn bioperturbado (PMB), Puerto Madryn no bioperturbado (PMNB), Punta Ninfas no erosionado (PNNE) y Punta Ninfas erosionado (PNE). En muestras de suelos extraídas de 0 a 5 cm (PM y PN) y de 0 a 10 cm (ML) de profundidad se determinó la materia orgánica total (MOT) y la MOP por vía húmeda (MOPh) (Método Walkley y Black) y por ignición en mufla (MOPi) a 430 °C. En los Molisoles de ML y en los Aridisoles de PM la MOPi fue mayor que la MOPh, mientras que para los Aridisoles de PN no se registraron diferencias significativas entre los dos métodos. Para los suelos con carbonatos (PM) o con alofanos (ML), el método por ignición sobreestimó los contenidos de MOP. La MOT presentó una alta correlación con la MOPh y con la MOPi para todos los suelos en conjunto (r2 = 0,89 y r2 = 0,73, respectivamente). El suelo que presentó una mayor relación MOP/MOT fue PNNE. En contraste, el suelo PNE, mostró los valores más bajos para esta relación, lo que indicaría, por un lado, que la poca MO que contienen estos suelos está predominantemente asociada a la fracción < de 0,053 mm, y por el otro, que la erosión afecta en mayor medida las reservas de MOP que las de MOT. Para los suelos PM, la relación MOPi/MOT fue mayor que uno, debido a la sobreestimación del método por ignición en estos suelos con abundante carbonatos. Tanto la MOT como la MOP determinada por los dos métodos, han permitido detectar diferencias entre tipos de manejo o estado de degradación de los suelos. De todas maneras, la MOP es proporcionalmente más afectada por la erosión y el pastoreo que la MOT, lo cual nos permitiría considerarla como un buen indicador de cambios en la calidad de los suelos bajo condiciones de pastoreo o afectados por procesos erosivos.Particulate organic-matter (MOP) is a dynamic soil component that quickly and selectively responds to management changes and to different disturbance regimes. We compared two techniques to determine the MOP content in different soils and assessed the potential of this variable as an indicator of soil quality. We studied the soils of three ecological sites located in the province of Chubut under different management schemes or affected by different disturbance regimes: Media Luna exclosure (MLC), Media Luna-grazing (MLP ), Puerto Madryn bioturbed (PMB), Puerto Madryn nonbioturbed (PMNB), Punta Ninfas uneroded (PNNE) and Punta Ninfas eroded (PNE). We collected soil samples from the 0 to 5 cm (PM and PN) or 0 to 10 cm (ML) depths to determine total soil organic-matter (MOT) and MOP using wet combustion MOPh (Walkley and Black method) and weight loss-on-ignition in a high temperature oven set at 430° C (MOPi). In the Mollisols and the Aridisols from Puerto Madryn, MOPi was higher than MOPh; in the Aridisols from Punta Ninfas, however, the differences between MOPi and MOPh were not significant. In soils with high calcium carbonate (PMB and PMNB) or allophane (MLC and MLP) contents, the loss-on-ignition method overestimated MOP contents. The MOT contents were highly correlated to both MOPh and MOPi for all soils (r2 = 0.89 and r2 = 0.73, respectively). Both MOT and MOP were sensitive to land management and soil erosion. The soil that displayed the greatest MOP/ MOT ratio was the PNNE. On the contrary, the PNE site showed the lowest values for this ratio, which would indicate that the low MOT content of this soil is predominantly associated to the < 0.053 mm fraction, and that the erosion process decreased the MOP reserves more than the MOT. For the Puerto Madryn soils, the MOPi / MOT ratio was greater than 1. This seems to be mainly due to the overestimation of the loss-on-ignition method in soils with abundant carbonates. Both MOT and MOP, determined by the two methods, can be used to detect differences in management or the state of soil degradation. However, MOP seemed to be more affected by soil erosion and sheep grazing compared to MOT. These results would allow us to consider MOP as a good indicator of changes in soil quality by either soil erosion or sheep grazing.Fil: Videla, Sonia Lina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico; ArgentinaFil: Rostagno, Cesar Mario. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico; ArgentinaFil: Toyos, Maria Alicia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico; Argentin

Psychoeducational preventive treatment for women at risk of postpartum depression: study protocol for a randomized controlled trial, PROGEA

Background: Postpartum depression is a disease with a prevalence of 20% that has deleterious consequences not only for the mother but also for the baby and can cause delays in physical, social and cognitive development. In this context, the European Union Committee on Public Health has declared it essential that preventative measures are taken by centres providing care for women with a multidisciplinary approach. PROGEA is a multicentre, single-blind randomized, 3-year, longitudinal clinical trial aiming to evaluate the efficacy of a psychoeducational programme in preventing postpartum depression in at-risk women, based on a range of clinical variables, and explore prognostic factors. This paper describes the methods and rationale behind the study. Methods: We will study women receiving treatment as usual plus a psychoeducation cognitive behavioural therapy (CBT)-based intervention and a control group receiving only treatment as usual. The sample will be recruited from an incidental sampling of pregnant women in two health regions. We will recruit 600 women in the third trimester of pregnancy who consent to take part in the study. Almost half of the women, about 280, would be expected to have some risk factors for postpartum depression. All those found to have risk factors will be evaluated, and we estimate that a quarter will be classified as at-risk of developing postpartum depression as measured with the Edinburgh Postnatal Depression Scale. This subset will be randomly allocated to receive treatment as usual with or without the CBT intervention. Six sessions of CBT (1 individual and 5 group) will be offered by a psychologist. Discussion: Findings from this study will be used to design a definitive study that will examine the clinical and cost-effectiveness of the CBT-based intervention in improving the mood of women in the postpartum period.This work was supported by local grants from the Department of Education, Linguistic Policy and Culture of the Basque Country Government (2011111110)

Pure Membranous Lupus Nephritis: Description of a Cohort of 150 Patients and Review of the Literature

Objectives The course and long-term outcome of pure membranous lupus nephritis (MLN) are little understood. The aims of this study are to evaluate the clinical features, course, outcome and prognostic indicators in pure MLN and to determine the impact of ethnicity and the type of health insurance on the course and prognosis of pure MLN. Methods We conducted a retrospective review of medical records of 150 patients with pure MLN from Spain and the USA. Results Mean age was 34.2±12.5 and 80% were women. Sixty-eight percent of patients had nephrotic syndrome at diagnosis. The average serum creatinine was 0.98±0.78mg/dl. Six percent of patients died and 5.3% developed end-stage renal disease (ESRD). ESRD was predicted by male sex, hypertension, dyslipidemia, high basal 24h-proteinuria, high basal serum creatinine and a low basal creatinine clearance. Age, cardiac insufficiency, peripheral artheriopathy, hemodialysis and not having received mycophenolate mofetil or antimalarials for MLN predicted death. Conclusions Pure MLN frequently presents with nephrotic syndrome, high proteinuria and normal serum creatinine. Its prognosis is favourable in maintaining renal function although proteinuria usually persists over time. Baseline cardiovascular disease and not having a health insurance are related with poor prognosis

Sorption of Selenium(IV) and Selenium(VI) onto Iron Oxide/Hydroxide-Based Carbon Materials: Activated Carbon and Carbon Foam

Selenium pollution in water is a worldwide issue. Se(IV) and Se(VI) are mainly found in contaminated water due to their high solubility and mobility; their presence poses a serious risk as they can severely harm human health. Although iron oxide and hydroxide nanoparticles can be efficient candidates for the removal of selenium oxyanions due to their high adsorption capacity, the role of each iron species has not been fully elucidated. Furthermore, iron species are often found to be less effective for Se(VI) than Se(IV). The challenge and novelty of this study was to develop a carbon material impregnated with different iron phases, including oxides (magnetite/hematite) and hydroxides (goethite/lepidocrocite) capable of removing both Se(IV) and Se(VI). Since the phase and morphology of the iron nanoparticles play a significant role in Se adsorption, the study evaluated both characteristics by modifying the impregnation method, which is based on an oxidative hydrolysis with FeSO4 7H2O and CH3COONa, and the type of carbonaceous support (activated carbon or sucrose-based carbon foam). Impregnated activated carbons provide better removal efficiencies (70–80%) than carbon foams (<40%), due to their high surface areas and point zero charges. These results show that the adsorption of Se(VI) is more favorable on magnetic oxides (78%) and hydroxides (71%) than in hematite (<40%). In addition, the activated carbon decorated with magnetite showed a high adsorption capacity for both selenium species, even in alkaline conditions, when the sorbent surface is negatively charged. A mechanism based on the adsorption of inner-sphere complexes was suggested for Se(IV) immobilization, whereas Se(VI) removal occurred through the formation of outer-sphere complexes and redox processes

Concentration, accumulation rates, Th fluxes, focusing factors, and productivity proxies on core PS97/093-2 over the past 400,000 years

Changes in Southern Ocean export production have broad biogeochemical and climatic implications. Specifically, iron fertilization likely increased subantarctic nutrient utilization and enhanced the efficiency of the biological pump during glacials. However, past export production in the subantarctic Southeast Pacific is poorly documented, and its connection to Fe fertilization, potentially related to Patagonian Ice Sheet dynamics is unknown. We report biological productivity changes over the past 400 ka, based on a combination of 230Thxs-normalized and stratigraphy-based mass accumulation rates of biogenic barium, organic carbon, biogenic opal, and calcium carbonate as indicators of paleo-export production in a sediment core upstream of the Drake Passage (57.5º S; 70.3º W). In addition, we use fluxes of iron and lithogenic material as proxies for terrigenous input, and thus potential micronutrient supply. Stratigraphy-based mass accumulation rates are strongly influenced by bottom-current dynamics, which result in variable sediment focussing or winnowing at our site. Carbonate is virtually absent in the core, except during peak interglacial intervals of the Holocene, and Marine Isotope Stages (MIS) 5 and 11, likely caused by transient decreases in carbonate dissolution. All other proxies suggest that export production increased during most glacial periods, coinciding with high iron fluxes. Such augmented glacial iron fluxes at the core site were most likely derived from glaciogenic input from the Patagonian Ice Sheet promoting the growth of phytoplankton. Additionally, glacial export production peaks are also consistent with northward shifts of the Subantarctic and Polar Fronts, which positioned our site south of the Subantarctic Front and closer to silicic acid-rich waters of the Polar Frontal Zone. However, glacial export production near the Drake Passage was lower than in the Atlantic and Indian sectors of the Southern Ocean, which may relate to complete consumption of silicic acid in the study area. Our results underline the importance of micro-nutrient fertilization through lateral terrigenous input from South America rather than aeolian transport, and exemplify the role of frontal shifts and nutrient limitation for past productivity changes in the Pacific entrance to the Drake Passage