Free water surface and horizontal subsurface flow constructed wetlands: a comparison of performance in treating domestic graywater

2012 Fall.Includes bibliographical references.Communities throughout the United States and abroad are seeking innovative approaches to sustaining their freshwater resources. Graywater reuse for non-potable demands is gaining popularity because it allows for the reuse of minimally contaminated wash water, generated and treated on site. Graywater is defined as any wastewater generated at the home or office including wastewater from the laundry, shower, and bathroom sinks but excluding water from the toilets, kitchen sinks, and dishwasher. When compared to other wastewater generated in the home, graywater is contaminated with lower concentrations of organics, solids, nutrients, and pathogens. These characteristics make the water suitable for reuse with negligible treatment when compared to other domestic wastewater sources. Graywater reuse for non-potable demands reduces the demand for treated water and preserves source waters. One method of treating graywater at a community scale for irrigation reuse is constructed wetlands. Despite widespread interest in this innovative approach, limited guidance is available on the design and operation of constructed wetlands specific to graywater treatment. The foremost objective of this research was to compare the performance of a free water surface constructed wetland (FWS) to a horizontal subsurface constructed wetland (SF) for graywater treatment and to assess their ability to meet water quality standards for surface discharge and reuse. This was done by comparison of percent (%) mass removal rates and requisite surface areas (SA) based on determined removal rates ( k ). Aerial loading rates were compared to EPA suggested aerial loading rates in an attempt to provide recommendations for target effluent concentrations. Determining contaminant removal rates is important for creating wetland design standards for graywater treatment and reuse. Contaminant removal rates were evaluated over the summer and fall of 2010 and 2011 for a SF wetland. These removal rates were compared to the removal rates evaluated over a two year period (2008-2010) for a FWS wetland. Another objective was to determine the % mass removal of three common anionic surfactants in constructed wetlands (both FWS and SF) and finally, the possibility of incorporating constructed wetlands into greenhouse community garden centers as an option to reduce the losses resulting from evapotranspiration (ET) in arid climates was explored briefly. The results indicate that SF wetlands provide relatively stable and more efficient treatment year round when compared to FWS wetlands. In particular, the SF wetland showed statistically significant higher mass removal of both biological oxygen demand (BOD5 ) and total nitrogen (TN) than the FWS wetland during winter months (P=0.1 and 0.005; α=0.1). When all the seasons were compared for each wetland individually there was a statistically significant degree of removal for BOD5 and TN between the seasons in the FWS wetland (P=0.09 and 0.04; α=0.1) while there was none in the SF wetland (P=1.0 and 0.9; α=0.1). These results are consistent with other findings in the literature. When mass removals were compared to HLRs, the trends support the ability of SF wetlands to function across a wide range of HLRs and climatic conditions, whereas FWS wetlands are less capable of performing well under less than ideal conditions. Results of the k-C* and SA analyses, though limited in their completeness, suggest once again that SF wetlands are capable of increased rates of removal not only during the warm summer months but also during the winter and transition months. Specifically, nitrification and denitrification processes may be contributing to TN removal in the SF wetland, particularly during senescent periods. Surfactant removal was also consistent with findings in the literature, with 50% removal of LAS and greater than 70% removal of AES/AS, suggesting that LAS is more persistent

Ecology of Juvenile Walleye Pollock, Theragra chalcogramma: Papers from the workshop "The Importance of Prerecruit Walleye Pollock to the Bering Sea and North Pacific Ecosystems" Seattle, Washington, 28-30 October 1993

The Alaska Fisheries Science Center (AFSC), National Marine Fisheries Service (NMFS), hosted an international workshop, 'The Importance of Prerecruit Walleye Pollock to the Bering Sea and North Pacific Ecosystems," from 28 to 30 October 1993. This workshop was held in conjunction with the annual International North Pacific Marine Science Organization (PICES) meeting held in Seattle. Nearly 100 representatives from government agencies, universities, and the fishing industry in Canada, Japan, the People's Republic of China, Russia, and the United States took part in the workshop to review and discuss current knowledge on juvenile pollock from the postlarval period to the time they recruit to the fisheries. In addition to its importance to humans as a major commercial species, pollock also serves as a major forage species for many marine fishes, birds, and mammals in the North Pacific region. (PDF file contains 236 pages.

Changes over time in the spatial distribution of walleye pollock (Theragra chalcogramma) in the Gulf of Alaska, 1984-1996

Triennial bottom trawl survey data from 1984 to 1996 were used to evaluate changes in the summer distribution of walleye pollock in the western and central Gulf of Alaska. Differences between several age groups of pollock were evaluated. Distribution was examined in relation to several physical characteristics, including bottom depth and distance from land. Interspecies associations were also analyzed with the Bray-Curtis clustering technique to better understand community structure. Our results indicated that although the population numbers decreased, high concentrations of pollock remained in the same areas during 1984–96. However, there was an increase in the number of stations where low-density pollock concentrations of all ages were observed, which resulted in a decrease in mean population density of pollock within the GOA region. Patterns emerging from our data suggested an alternative to Mac-Call’s “basin hypothesis” which states that as population numbers decrease, there should be a contraction of the population range to optimal habitats. During 1984–96 there was a concurrent precipitous decline in Steller sea lions in the Gulf of Alaska. The results of our study suggest that decreases in the mean density of adult pollock, the main food in the Steller sea lion diet, combined with slight changes in the distribution of pollock (age-1 pollock in particular) in the mid-1980s, may have contributed to decreased foraging efficiency in Steller sea lions. Our results support the prevailing conceptual model for pollock ontogeny, although there is evidence that substantial spawning may also occur outside of Shelikof Strait

Growth and formation of annual zones in whole otoliths of Greenland halibut, a slow-growing deep-water fish

-There is currently no generally agreed and validated method for age estimation of Greenland halibut (Reinhardtius hippoglossoides) from otoliths, and ageing of intermediate sized individuals of this deep-water flatfish is considered particularly uncertain. To estimate otolith growth and annual zone formation in this size range, a large oxytetracycline tagging experiment was undertaken in 2005–08 in the nursery grounds north of the Svalbard Archipelago. By January 2015, 89 of the recaptured fish had both been at large for between 1 and 6 years and had reliable length measurements at release and recapture; 29 of the recaptures were returned with whole otoliths and with a chemical time stamp that allowed identification of otolith growth patterns during time at large. Four age readers interpreted the otoliths without knowing the position of the time stamps. The expected number of zones during time at large was between three and six for 79% of recaptures, and the mean reader bias was only 0.04–0.56 years. Juvenile growth was quantified and the data were analysed in relation to sex and recapture area. This study contributes to a fully validated ageing method for use in stock assessments of this commercially important species

Modeling the Galaxy Distribution in Clusters using Halo Cores

The galaxy distribution in dark matter-dominated halos is expected to approximately trace the details of the underlying dark matter substructure. In this paper we introduce halo `core-tracking' as a way to efficiently follow the small-scale substructure in cosmological simulations and apply the technique to model the galaxy distribution in observed clusters. The method relies on explicitly tracking the set of particles identified as belonging to a halo's central density core, once a halo has attained a certain threshold mass. The halo cores are then followed throughout the entire evolution of the simulation. The aim of core-tracking is to simplify substructure analysis tasks by avoiding the use of subhalos and, at the same time, to more easily account for the so-called ``orphan'' galaxies, which have lost substantial dark mass due to tidal stripping. We show that simple models based on halo cores can reproduce the number and spatial distribution of galaxies found in optically-selected clusters in the Sloan Digital Sky Survey. We also discuss future applications of the core-tracking methodology in studying the galaxy-halo connection.Comment: 17 pages, 20 figures, 1 Appendix; version accepted by OJ

Climate change impacts on polar marine ecosystems: Toward robust approaches for managing risks and uncertainties

The Polar Regions chapter of the Intergovernmental Panel on Climate Change's Special Report on the Ocean and Cryosphere in a Changing Climate (SROCC) provides a comprehensive assessment of climate change impacts on polar marine ecosystems and associated consequences for humans. It also includes identification of confidence for major findings based on agreement across studies and weight of evidence. Sources of uncertainty, from the extent of available datasets, to resolution of projection models, to the complexity and understanding of underlying social-ecological linkages and dynamics, can influence confidence. Here we, marine ecosystem scientists all having experience as lead authors of IPCC reports, examine the evolution of confidence in observed and projected climate-linked changes in polar ecosystems since SROCC. Further synthesis of literature on polar marine ecosystems has been undertaken, especially within IPCC's Sixth Assessment Report (AR6) Working Group II; for the Southern Ocean also the Marine Ecosystem Assessment for the Southern Ocean (MEASO). These publications incorporate new scientific findings that address some of the knowledge gaps identified in SROCC. While knowledge gaps have been narrowed, we still find that polar region assessments reflect pronounced geographical skewness in knowledge regarding the responses of marine life to changing climate and associated literature. There is also an imbalance in scientific focus; especially research in Antarctica is dominated by physical oceanography and cryosphere science with highly fragmented approaches and only short-term funding to ecology. There are clear indications that the scientific community has made substantial progress in its ability to project ecosystem responses to future climate change through the development of coupled biophysical models of the region facilitated by increased computer power allowing for improved resolution in space and time. Lastly, we point forward—providing recommendations for future advances for IPCC assessments.publishedVersio

Effects of interdecadal climate variability on the oceanic ecosystems of the northeast Pacific Ocean [abstract]

EXTRACT (SEE PDF FOR FULL ABSTRACT): It is increasingly apparent that a major reorganization of the Northeast Pacific biota transpired following a climatic "regime shift" in the mid-1970s. In this paper, we characterize the effects of interdecadal climate forcing on the oceanic ecosystems of the northeastern Pacific Ocean

ICES and PICES Strategies for Coordinating Research on the Impacts of Climate Change on Marine Ecosystems

The social, economic, and ecological consequences of projected climate change on fish and fisheries are issues of global concern. In 2012, the International Council for the Exploration of the Sea (ICES) and the North Pacific Marine Science Organization (PICES) established a Strategic Initiative on Climate Change Effects on Marine Ecosystems (SICCME) to synthesize and to promote innovative, credible, and objective science-based advice on the impacts of climate change on marine ecosystems in the Northern Hemisphere. SICCME takes advantage of the unique and complementary strengths of the two organizations to develop a research initiative that focuses on their shared interests. A phased implementation will ensure that SICCME will be responsive to a rapidly evolving research area while delivering ongoing syntheses of existing knowledge, thereby advancing new science and methodologies and communicating new insights at each phase