Soil carbon loss from drained agricultural peatland after coverage with mineral soil.

Drainage for agriculture has turned peatlands from a net sink to a net source of carbon (C). In order to reduce the environmental footprint of agricultural peatland drainage, and to counteract soil subsidence, mineral soil coverage is becoming an increasingly used practice in Switzerland. To explore the effect of mineral soil coverage on soil C loss and the source of CO2 from peatland drained for agriculture, we utilized the radiocarbon signature (F14C) of soil C and emitted CO2 in the field. The experiment, located in the Swiss Rhine Valley, was carried out on two adjacent drained organic soils, either without mineral soil cover (reference 'Ref'), or covered with mineral soil (thickness ~ 40 cm) (coverage 'Cov') 13 years ago. Drainage already commenced 130 years ago and the site was managed as meadow since the 1970ies. Drainage induced 41-75 kg C m-2 loss, which is equivalent to annual C loss rates of 0.49-0.58 kg C m-2 yr-1 and 0.31-0.63 kg C m-2 yr-1 for Cov and Ref, respectively. Mineral soil coverage had no significant effect on the amount of heterotrophic respiration, however, at Cov, the radiocarbon signature of heterotrophic CO2 was significantly (p<0.01) younger than at Ref, indicating that mineral soil coverage moved the source of decomposition of soil organic carbon (SOC) from a higher share of old peat towards a higher share of relatively younger material. In summary, our study lends support to the hypothesis that mineral soil coverage might reduce the decomposition of old peat underneath, and may therefore be a promising peatland management technique for the future use of drained peatland for agriculture.

Metal biogeochemistry in constructed wetlands based on fluviatile sand and zeolite- and clinopyroxene-dominated lava sand.

For the first time, speciation of Fe, Mn, Zn, Ni, Cu and Pb was determined along the profiles of 8 constructed wetlands (CWs) consisting of fluviatile sand (Fluv), clinopyroxene-dominated lava sand (Cl-LS) and zeolite-dominated lava sand (Ze-LS), aiming at quantifying metal behaviour in CWs and the impact caused by different filter materials. With the exception of Mn, which underwent reductive dissolution, CWs were sinks for the studied metals. Metal accumulation rates differed in the following order: Ze-LS ≥ Cl-LS > Fluv CWs, reflecting the highest metal adsorption capacity and the lowest hydraulic conductivity of Ze-LS. Sequential extraction data indicated the highest metal mobility (readily mobilised and adsorbed fractions summing up to ~60%) in Fluv CWs, implying a higher risk of metal release into adjacent environments if Fluv from CWs will be improperly disposed after usage. Zinc and Ni were transported into the deeper CW layers to a larger extent than Cu and Pb, reflecting adsorption affinity to all filter materials in the order of Pb > Cu > Zn > Ni. Therefore, understanding metal speciation and mobility in such materials is crucial when they are considered for application as filters in CWs.

Executive dysfunction in first-episode schizophrenia and relationship to duration of untreated psychosis: the West London Study.

BACKGROUND: Many studies have demonstrated early generalised cognitive impairment in schizophrenia. AIMS: To examine executive function in first-episode schizophrenia, characterise the nature of the impairment and specify any relationships with symptoms and duration of untreated psychosis (DUP). METHOD: Patients (n = 136) and normal controls (n = 81) were assessed with the Cambridge Automated Neuropsychological Test Battery, National Adult Reading Test IQ, and Scales for the Assessment of Positive and Negative Symptoms. RESULTS: Memory and executive impairments in patients were independent of IQ level. Spatial working memory was impaired because of inadequate strategy use. On a planning task, patients showed reduced planning times and suboptimal problem-solving. On an attentional set-shifting task, 75% of patients were able to perform an extra-dimensional shift thought to be a core attribute of prefrontal cortex function. Those who failed had significantly longer DUP. CONCLUSIONS: Prefrontal cortex function deteriorates at the onset of psychosis and continues to worsen over time.

Characterizing the redox status in three different forested wetlands with geochemical data.

Biogeochemistry and regulation of redox processes in wetlands and especiallytheir source sink functions regarding sulfur, nitrogen, iron, and alkalinity are still poorly understood and become increasingly important in a world of global change. We investigated three forested wetlands within the Lehstenbach catchment (Fichtelgebirge, Northeastern Bavaria, Germany) differing in their degree of water saturation, vegetation, and availability of iron with stable sulfur analysis as well as geochemical analysis (iron, nitrate, sulfate, and oxygen contents in soil solutions and groundwater). Results indicated considerable nitrate, sulfate, and iron reduction rates bound to high spatial and temporal heterogeneity at all three sites. Sites differed significantly regarding their oxygen saturation and their dynamics of sulfur and iron reduction. The sequential reduction chain did not seem an applicable concept to describe redox dynamics at micro- (cm(2)) or mesoscale (m(2)) because of (1) high small-scale heterogeneity and (2) an absence of clear relationships between redox indicative parameters. The latter might be caused by redox processes occurring simultaneously at the investigated spatial and temporal scales. However, a tendency toward exclusive relationships between oxygen and iron, nitrate and iron, and delta34S with oxygen, nitrate, and sulfate indicated that the sequential reduction chain might be a suitable modeling concept for macroscale (km(2)) investigations with large sample numbers.