Band-steaming reduces laborious hand-weeding in vegetables

Band-steaming is a new method that may reduce the need for hand-weeding in demanding row crops like carrot and drilled onion. Band-steaming only affects a soil volume equal to the intra-row area of the subsequent crop, and effectively kills the weed seeds in this soil volume. Side-effects on beneficial soil organisms are minimized as compared to current steaming technology, but still need to be assessed

Recent results in the development of band steaming for intra-row weed control

The recent achievements with developing band-steaming techniques for intra-row weed control in vegetables are presente

Effekter af damp på ukrudt og mikroliv

Ukrudt i rækkeafgrøder kan begrænses med en ny teknik, hvor jorden dampes i smalle striber. Derfor kan dampning være interessant i økologisk jordbrug. Teknikken påvirker dog også jordens mikroliv

Risiko ved transport af farligt gods

Projektet ”Transport af farligt gods”, er næsten afsluttet. Slutrapporten publiceres i 1999. Den indeholder to risikomodeller for transporter af farligt gods: en model for jernbanetrafik og en model for vejtrafik. Disse modeller angiver risikoen for udslip af forskellige størrelser ved givne transporter. Endvidere angives modeller for konsekvenserne af givne udslip, dels hu-mane konsekvenser i form af fN-kurver for dødsfald, dels miljøkonsekvenser i form af jord-og grundvandsforurening og i form af forurening af overfladevand. Modellerne indlægges i et GIS, som kan anskueliggøre konsekvensernes geografiske fordeling totalt eller vise forskelle ved forskelligt rutevalg for en given transport

Microbial community assembly and evolution in subseafloor sediment

Bacterial and archaeal communities inhabiting the subsurface seabed live under strong energy limitation and have growth rates that are orders of magnitude slower than laboratory-grown cultures. It is not understood how subsurface microbial communities are assembled and whether populations undergo adaptive evolution or accumulate mutations as a result of impaired DNA repair under such energy-limited conditions. Here we use amplicon sequencing to explore changes of microbial communities during burial and isolation from the surface to the > 5,000-y-old subsurface of marine sediment and identify a small core set of mostly uncultured bacteria and archaea that is present throughout the sediment column. These persisting populations constitute a small fraction of the entire community at the surface but become predominant in the subsurface. We followed patterns of genome diversity with depth in four dominant lineages of the persisting populations by mapping metagenomic sequence reads onto single-cell genomes. Nucleotide sequence diversity was uniformly low and did not change with age and depth of the sediment. Likewise, therewas no detectable change inmutation rates and efficacy of selection. Our results indicate that subsurface microbial communities predominantly assemble by selective survival of taxa able to persist under extreme energy limitation

Impact of PCB and p,p′-DDE Contaminants on Human Sperm Y:X Chromosome Ratio: Studies in Three European Populations and the Inuit Population in Greenland

OBJECTIVE: Recent studies indicate that persistent organohalogen pollutants (POPs) may contribute to sex ratio changes in offspring of exposed populations. Our aim in the present study was to investigate whether exposure to 2,2′,4,4′,5,5′-hexachlorobiphenyl (PCB-153) and dichlorodiphenyldichloroethene (p,p′-DDE) affects sperm Y:X chromosome distribution. SUBJECTS AND METHODS: We obtained semen and blood for analysis of PCB-153 and p,p′-DDE levels from 547 men from Sweden, Greenland, Poland (Warsaw), and Ukraine (Kharkiv), with regionally different levels of POP exposure. The proportion of Y- and X-chromosome–bearing sperm in the semen samples was determined by two-color fluorescence in situ hybridization analysis. RESULTS: Swedish and Greenlandic men had on average significantly higher proportions of Y sperm (in both cohorts, 51.2%) and correspondingly higher lipid-adjusted concentrations of PCB-153 (260 ng/g and 350 ng/g, respectively) compared with men from Warsaw (50.3% and 22 ng/g) and Kharkiv (50.7% and 54 ng/g). In the Swedish cohort, log-transformed PCB-153 and log-transformed p,p′-DDE variables were significantly positively associated with Y-chromosome fractions (p-values 0.04 and < 0.001, respectively). On the contrary, in the Polish cohort PCB-153 correlated negatively with the proportion of Y-bearing fraction of spermatozoa (p = 0.008). CONCLUSIONS: The present study indicates that POP exposure might be involved in changing the proportion of ejaculated Y-bearing spermatozoa in human populations. Intercountry differences, with different exposure situations and doses, may contribute to varying Y:X chromosome ratios

Xenoandrogenic Activity in Serum Differs across European and Inuit Populations

Background: Animal and in vitro studies have indicated that human male reproductive disorders can arise as a result of disrupted androgen receptor (AR) signalling by persistent organic pollutants (POPs) . Our aim in the present study was to compare serum xenoandrogenic activity between study groups with different POP exposures and to evaluate correlations to the POP proxy markers 2,2\ub4,4,4\ub4,5,5\ub4-hexachlorobiphenyl (CB-153) and 1,1-dichloro-2,2-bis(p-chlorophenyl) -ethylene (p,p\ub4-DDE) .Methods: We determined xenoandrogenic activity in the serum fraction containing the lipophilic POPs but free of endogenous hormones. Adult male serum (n = 261) from Greenland, Sweden, Warsaw (Poland) , and Kharkiv (Ukraine) was analyzed. Xenoandrogenic activity was determined as the effect of serum extract alone (XAR) and in the presence of the synthetic AR agonist R1881 (XARcomp) on AR transactivated luciferase activity.Results: The study groups differed significantly with respect to XARcomp activity, which was increased in the Inuits and decreased in the European study groups ; we observed no difference for XAR activity. We found the highest level of the AR antagonist p,p\ub4-DDE in Kharkiv, and accordingly, this study group showed the highest percent of serum samples with decreased XARcomp activities. Furthermore, the percentage of serum samples with decreased XARcomp activities followed the p,p\ub4-DDE serum level for the European study groups. No correlations between serum XAR or XARcomp activities and the two POP markers were revealed.Conclusions: The differences in XARcomp serum activity between the study groups suggest differences in chemical exposure profiles, genetics, and/or lifestyle factors