A.R. Cole | USGS Science

USGS2021

Effects-based monitoring of bioactive compounds associated with municipal wastewater treatment plant effluent discharge to the South Platte River, Colorado, USA

Previous studies have detected numerous organic contaminants and in vitro bioactivities in surface water from the South Platte River near Denver, Colorado, USA. To evaluate the temporal and spatial distribution of selected contaminants of emerging concern, water samples were collected throughout 2018 and 2019 at 11 sites within the S. Platte River and surrounding tributaries with varying proximities to a major wastewater treatment plant (WWTP). Water samples were analyzed for pharmaceuticals, pesticides, steroid hormones, and wastewater indicators and screened for in vitro biological activities. Multiplexed, in vitro assays that simultaneously screen for agonistic activity against 24 human nuclear receptors detected estrogen receptor (ER), peroxisome proliferator activated receptor-gamma (PPARγ), and glucocorticoid receptor (GR) bioactivities in water samples near the WWTP outflow. Targeted in vitro bioassays assessing ER, GR, and PPARγ agonism corroborated bioactivities for ER (up to 55 ± 9.7 ng/L 17β-estradiol equivalents) and GR (up to 156 ± 28 ng/L dexamethasone equivalents), while PPARγ activity was not confirmed. To evaluate the potential in vivo significance of the bioactive contaminants, sexually-mature fathead minnows were caged at six locations upstream and downstream of the WWTP for 5 days after which targeted gene expression analyses were performed. Significant up-regulation of male hepatic vitellogenin was observed at sites with corresponding in vitro ER activity. No site-related differences in GR-related transcript abundance were detected in female adipose or male livers, suggesting observed environmental concentrations of GR-active contaminants do not induce a detectable in vivo response. In line with the lack of detectable targeted in vitro PPARɣ activity, there were no significant effects on PPARɣ-related gene expression. Although the chemicals responsible for GR and PPAR-mediated bioactivities are unknown, results from the present study provide insights into the significance (or lack thereof) of these bioactivities relative to short-term in situ fish exposures.

Environmental Pollution↗

USGS1996

Late quaternary deltaic and carbonate sedimentation in the Gulf of Papua foreland basin: Response to sea-level change

The rivers that drain the wet, mountainous island of New Guinea discharge about 1.5 billion tonnes/yr of sediments into the adjacent seas, including the foreland basin between New Guinea and Australia. Despite this huge sediment input, there appears to have been only limited deposition in the Gulf of Papua during the (Holocene) postglacial rise in sea level. Seismic and core data indicate that the transgressive systems tract in the Gulf of Papua is thin and patchy. It is confined to regions within and north of an incised, east-west-trending shelf-valley system. Of the possible explanations for the absence of a significant transgressive systems tract, inland storage and along- and off-shelf transport of the sediment are of greatest significance. Reef growth up to the latitude of the east-west-trending incised-valley system in the southern Gulf of Papua is considered to have been facilitated by a northward-flowing coastal boundary current, the Coral Sea Coastal Current. This current now sweeps turbid, brackish waters and terrigenous sediments discharged by the rivers northwards away from the reefs. An observed northward offset in transgressive sediments in relation to the axis of the shelf valleys suggests that such a northward.flowing shelf current operated during the late Pleistocene and early Holocene. The northern limit of the Great Barrier Reef could thus be controlled by the balance between fluvial sediment supply and northward advection of suspended sediment by the Coral Sea Coastal Current. This current may also be important in maintaining a supply of clear water to the eastern Gulf of Papua, thus enabling photosynthesis and the flourishing of calcareous-algae ( Halimeda ) bioherms or biostromes at depths of up to 100 m over much of the middle and outer shelf, directly offshore of the modern Fly Delta. These carbonate sediments represent the exposed maximum flooding surface and condensed section. Modern highstand delta deposits have begun to prograde over this layer on the inner shelf.

Journal of Sedimentary Research↗