Suchergebnisse

AbstractHistorical industrial activities at the Horn Richterwil, on the shore of Lake Zurich (Switzerland), caused widespread metal contamination on land and in the adjacent lake sediments. This study provides an estimation of the age and source of the contamination by using XRF core scanning, ICP-OES, and Hg-AFS for quantitative measurements of trace metals and MC-ICP-MS for the stable isotope analysis of mercury. Radiometric dating ($$^{137}$$


137

Cs, $$^{210}$$


210

Pb, and Pu dating) of two proximal cores and varve chronology in a distal core suggest two different contaminations, one stemming from around 1960 (Zn, Cd) and an earlier one from 1880 (Cr, Cu, Hg, Pb, Sn). The XRF data suggest two different contamination pathways: one by landfill of contaminated soil and another one by industrial wastewater effluents. Maximum concentrations found within all samples are in the range of per mil (dry weight) for Cr, Cu, Hg, Pb, Sn, and Zn and lie within the top 10 cm of the sediment cores. The analysis of the mercury isotopic composition ($$\delta ^{202}$$

δ
202

Hg and $$\Delta ^{199}$$

Δ
199

Hg) shows a significantly different signature for one of the cores, indicating a second mercury source. We could not identify the exact source or process leading to the isotopic fractionation of mercury, but the isotopic data confirm two different sources.

<b><i>Background/Aims:</i></b> Heroin-assisted treatment (HAT) can improve the condition of heroin addicts still using street heroin after a methadone treatment. In Belgium, a new trial compared the efficacy of a HAT to existing methadone maintenance treatment. <b><i>Methods:</i></b> In this randomised controlled trial, HAT was limited to 12 months. Participants were assessed every 3 months. They were responders if they showed improvement on the level of street heroin use, health or criminal involvement. <b><i>Results:</i></b> 74 participants were randomised in the trial. The experimental group (n = 36) counted 30% of responders more than the control group (n = 38) at each assessment point (p < 0.05), except at 12 months where the difference (11%) was no longer significant (p = 0.35). Still, after 12 months, participants in the experimental group reported significantly greater improvements (p < 0.05) than the control group on the level of street heroin use and on the level of physical and mental health. Both groups reported significantly less criminal acts after 12 months (p < 0.001), but with no significant difference between the groups. <b><i>Conclusions:</i></b> This trial confirms the short-term efficacy of HAT for severe heroin addicts, who already failed methadone treatment.

Background/Aims: Heroin-assisted treatment (HAT) can improve the condition of heroin addicts still using street heroin after a methadone treatment. In Belgium, a new trial compared the efficacy of a HAT to existing methadone maintenance treatment. Methods: In this randomised controlled trial, HAT was limited to 12 months. Participants were assessed every 3 months. They were responders if they showed improvement on the level of street heroin use, health or criminal involvement. Results: 74 participants were randomised in the trial. The experimental group (n=36) counted 30% of responders more than the control group (n=38) at each assessment point (p<0.05), except at 12 months where the difference (11%) was no longer significant (p=0.35). Still, after 12 months, participants in the experimental group reported significantly greater improvements (p<0.05) than the control group on the level of street heroin use and on the level of physical and mental health. Both groups reported significantly less criminal facts after 12 months (p<0.001), but with no significant difference between the groups. Conclusions: This trial confirms the short-term efficacy of HAT for severe heroin addicts, who already failed methadone treatment. ; Peer reviewed

AbstractIntertidal sands are global hotspots of terrestrial and marine carbon cycling with strong hydrodynamic forcing by waves and tides and high macrofaunal activity. Yet, the relative importance of hydrodynamics and macrofauna in controlling these ecosystems remains unclear. Here, we compare geochemical gradients and bacterial, archaeal, and eukaryotic gene sequences in intertidal sands dominated by subsurface deposit-feeding worms (Abarenicola pacifica) to adjacent worm-free areas. We show that hydrodynamic forcing controls organismal assemblages in surface sediments, while in deeper layers selective feeding by worms on fine, algae-rich particles strongly decreases the abundance and richness of all three domains. In these deeper layers, bacterial and eukaryotic network connectivity decreases, while percentages of clades involved in degradation of refractory organic matter, oxidative nitrogen, and sulfur cycling increase. Our findings reveal macrofaunal activity as the key driver of biological community structure and functioning, that in turn influence carbon cycling in intertidal sands below the mainly physically controlled surface layer.