A Sampler for Measuring Deposited Fine Sediments in Streams1

Turner, Andy W., Jeff J. Hillis, and Charles F. Rabeni, 2012. A Sampler for Measuring Deposited Fine Sediments in Streams. Journal of the American Water Resources Association (JAWRA) 48(2): 366‐378. DOI: 10.1111/j.1752‐1688.2011.00618.x Abstract: Improvements and standardization of methodologies to quickly and accurately quantify deposited sediment in streams will allow advances in our understanding of biological effects of sedimentation. Most methods used to evaluate streambed conditions as part of biological monitoring or assessment programs are selected for ease of use, but can be subjective, inappropriate, and often of unknown accuracy. We developed a portable, light‐weight device to quantify deposited unconsolidated sediment (particles <2 mm) in wadeable streams. This deposited sediment sampler is a hand‐held unit that circumscribes an area of the streambed and through suction creates a force that suspends unconsolidated materials into a collector. Laboratory evaluations determined the efficiency (percent of available deposited sediment recovered) of the sampler to collect different sizes and concentrations of deposited sediment under differing streambed conditions, which allowed appropriate correction factors to be applied to each of four categories of streambed particle size. Field trials comparing our sampler to other methods commonly used by many state and federal agencies showed high comparability. The sampler can be constructed in just a few hours from inexpensive, easily obtained materials.     

Geomechanical analysis of the Naylor Field,Otway Basin,Australia: Implications for CO2 injection and storage

A geomechanical assessment of the Naylor Field, Otway Basin, Australia has been undertaken to investigate the possible geomechanical effects of CO₂ injection and storage. The study aims to evaluate the geomechanical behaviour of the caprock/reservoir system and to estimate the risk of fault reactivation. The stress regime in the onshore Victorian Otway Basin is inferred to be strike–slip if the maximum horizontal stress is calculated using frictional limits and DITF (drilling induced tensile fracture) occurrence, or normal if maximum horizontal stress is based on analysis of dipole sonic log data. The NW–SE maximum horizontal stress orientation (142°N) determined from a resistivity image log is broadly consistent with previous estimates and confirms a NW–SE maximum horizontal stress orientation for the Otway Basin.An analytical geomechanical solution is used to describe stress changes in the subsurface of the Naylor Field. The computed reservoir stress path for the Naylor Field is then incorporated into fault reactivation analysis to estimate the minimum pore pressure increase required to cause fault reactivation (ΔP_p).The highest reactivation propensity (for critically-oriented faults) ranges from an estimated pore pressure increase (ΔP_p) of 1 MPa to 15.7 MPa (estimated pore pressure of 18.5–33.2 MPa) depending on assumptions made about maximum horizontal stress magnitude, fault strength, reservoir stress path and Biot's coefficient. The critical pore pressure changes for known faults at Naylor Field range from an estimated pore pressure increase (ΔP_p) of 2 MPa to 17 MPa (estimated pore pressure of 19.5–34.5 MPa).     

Age and proximity to local ore-smelters as determinants of tissue metal levels in beaver (Castor canadensis) of the sudbury (Ontario) area

An examination of tissue metal levels in Sudbury-area beaver (Castor canadensis) revealed that animals in the vicinity of the local ore-smelters contained elevated burdens of Ni and Pb in the liver and kidneys. Tissue concentrations averaged 1.5- to 2.5-fold higher than background values and are believed to reflect accumulations resulting through food chain contamination. Tissue levels of Cu, Cd and Zn did not vary in relation to distance from source. Tissue Cd levels were uniformly elevated throughout the four populations examined and are believed to reflect an enhanced level of food chain transfer occurring on the poorly buffered, acid-sensitive soils of the area. Burden: body weight correlations indicated that tissue concentrations of Cd increased whereas Cu levels decreased as a function of animal age. Most striking among these age-related trends was the disproportionate uptake of Cd by renal tissues, resulting in 10-fold higher burdens than those present within the liver.     

Structural responses of Daucus carota root-organ cultures and the arbuscular mycorrhizal fungus, Glomus intraradices, to 12 pharmaceuticals

Pharmaceuticals and personal care products may enter the terrestrial environment through the amendment of agricultural soils with manure or biosolids with potential impacts on beneficial soil microbe populations. The beneficial symbiotic relationship between most plant species and arbuscular mycorrhizal fungi is a primary determinant of plant health and soil fertility. As such, there is increasing recognition of the need to study the impacts of anthropogenic stressors on plant-microbe interactions in soil ecotoxicology studies and risk assessment. A case study exploring the use of root-organ cultures to evaluate the effects of 12 common veterinary and human-use pharmaceuticals on the arbuscular mycorrhizal fungus, Glomus intraradices grown on Daucus carota root-organ cultures is presented. The bioassays were conducted over a 28-day exposure period at concentrations up to 1000mugl(-1). Root length and the fungal endpoints of hyphal growth and spore production were evaluated weekly during the study. Sulfamethoxazole and atorvastatin were the most phytotoxic compounds with EC(50) values of 45mugl(-1) and 65mugl(-1), respectively. Three compounds exhibited selective mycotoxicity, whereby the fungal symbiont was adversely affected at concentrations significantly less than that calculated for root length. The EC(50) for G. intraradices hyphal length was 45mugl(-1) for doxycycline, while carbamazepine and 17-alpha-ethynyl estradiol targeted spore production with EC(50) values of 113 and 116mugl(-1), respectively. The assay results indicate that the root lengths responded quickly to the presence of phytotoxic pharmaceuticals in the culture medium. Hyphal length is a sensitive endpoint after 21 days exposure, while spore production requires 28 days exposure before significant differences could be detected. Root-organ cultures provide an effective means to evaluate chemical stressors on arbuscular mycorrhizal fungi and can be used to screen for root-based phytotoxicity.