7 research outputs found
The Effects of Chronic Mercuric Chloride Ingestion in Female SpragueâDawley Rats on Fertility and Reproduction
Thirty-days-old female rats were chronically exposed, for 60 days, to 1or 2 mg/kg/day of mercuric chloride or an equivalent volume of water, via gavage. At 90 days of age they were mated with unexposed males. At approximately day 13 of gestation necropsies were performed on the females. Data were collected on the number of implantations and non-viable implantations in the uterus. No physical signs of Hg intoxication were seen except in weight gain. There were significantly fewer implantations in the high HgCl2 group, with significantly more non-viable implantations in the low and high HgCl2 groups, compared to controls. Lower levels of progesterone and higher levels of pituitary luteinizing hormone (LH) were found in the high HgCl2 group compared to controls, whereas pituitary follicle stimulating hormone levels (FSH), while not significant, showed a doseâ response relationship to HgCl2 levels. No difference was found in the number of corpora lutea. The experiment indicated low level chronic ingestion of mercuric chloride, in female rats, while not effecting ovulation, produced disruption of implantation and fetal viability. Lower progesterone levels, higher LH, and possibly FSH levels, indicate that mercuric chloride may have a disruptive effect in the corpora lutea which manifests itself after ovulation
The effects of chronic mercuric chloride ingestion in female SpragueâDawley rats on fertility and reproduction
The Effects of Job-Related Variables on Work-Family Conflict and The Influences of Work-Family Conflict on Organizational Commitment and Job Engagement
Catchment source contributions to the sediment-bound organic matter degrading salmonid spawning gravels in a lowland river, southern England
The ingress of particulate material into freshwater spawning substrates is thought to be contributing to the
declining success of salmonids reported over recent years for many rivers. Accordingly, the need for reliable
information on the key sources of the sediment problem has progressed up the management agenda. Whilst
previous work has focussed on apportioning the sources of minerogenic fine sediment degrading spawning
habitats, there remains a need to develop procedures for generating corresponding information for the potentially
harmful sediment-bound organic matter that represents an overlooked component of interstitial sediment.
A source tracing procedure based on composite signatures combining bulk stable 13C and 15N isotope values
with organic molecular structures detected using near infrared (NIR) reflectance spectroscopy was therefore
used to assess the primary sources of sediment-bound organic matter sampled from artificial spawning redds.
Composite signatures were selected using a combination of the KruskalâWallis H-test, principal component
analysis and GA-driven discriminant function analysis. Interstitial sediment samples were collected using
time-integrating basket traps which were inserted at the start of the salmonid spawning season and extracted
in conjunction with critical phases of fish development (eyeing, hatch, emergence, late spawning). Over the
duration of these four basket extractions, the overall relative frequency-weighted average median (±95%
confidence limits) source contributions to the interstitial sediment-bound organic matter were estimated to be
in the order: instream decaying vegetation (39 ± b1%; full range 0â77%); damaged road verges (28 ± b1%; full
range 0â77%); septic tanks (22 ± b1%; full range 0â50%), and; farm yard manures/slurries (11 ± b1%; full
range 0â61%). The reported procedure provides a promising basis for understanding the key sources of interstitial
sediment-bound organic matter and can be applied alongside apportionment for the minerogenic component of
fine-grained sediment ingressing the benthos. The findings suggest that human septic waste contributes to the
interstitial fines ingressing salmonid spawning habitat in the study area
Modelling the fate of oxidisable organic contaminants in groundwater
Subsurface contamination by organic chemicals is a pervasive environmental problem, susceptible to remediation by natural or enhanced attenuation approaches or more highly engineered methods such as pump-and-treat, amongst others. Such remediation approaches, along with risk assessment or the pressing need to address complex scientific questions, have driven the development of integrated modelling tools that incorporate physical, biological and geochemical processes. We provide a comprehensive modelling framework, including geochemical reactions and interphase mass transfer processes such as sorption/desorption, non-aqueous phase liquid dissolutio