Sanitation, renewable energy, and food security are among the most pressing global development needs of the century, especially for small cities with rapid population growth. Currently, 53% of the world’s population either lacks access to improved sanitation or discharges fecal waste to the environment without treatment. Furthermore, 80% of food consumed in developing regions is produced by 500 million small farms, and while many of them are still rain-fed, irrigated agriculture is increasing. The post-2015 Sustainable Development Goals, recently adopted by the United Nations, include targets to address the water-energy-food nexus. Wastewater reuse in agriculture can be an important solution for these goals, if it is done safely. Globally, 18 – 20 million hectares of agricultural land are irrigated with wastewater, but much is untreated, unregulated, or unsanctioned, causing concerns and uncertainty about health risks. There is a need to better understand pathogen removal in natural and non-mechanized wastewater treatment systems, such as waste stabilization ponds (WSPs) and upflow anaerobic sludge blanket (UASB) reactors, which are commonly used in small cities and towns. Riverbank filtration (RBF) is also a natural technique used by farmers in developing countries to treat surface water polluted with untreated sewage, but pathogen removal in these systems has seldom been assessed in developing countries. The focus of this dissertation is on pathogen removal in natural and non-mechanized wastewater treatment and reuse systems, to evaluate the health implications of water reuse for irrigation, with the following three objectives: 1) assess the current understanding of virus removal in WSP systems through a systematic review of the literature; 2) measure the removal of viruses and their association with particles in systems with WSPs, UASB reactors, or both; and 3) assess the fate and transport of pathogens and fecal indicators in wastewater treatment systems with direct and indirect reuse for irrigation to estimate microbial risks. To advance the understanding of virus removal in WSP systems, a comprehensive analysis of virus removal reported in the literature from 71 different WSP systems revealed only a weak to moderate correlation of virus removal with theoretical hydraulic retention time (HRT). For each log10 reduction of viruses a geometric mean of 14.5 days of retention was required, but the 95th percentile of the data analyzed was 54 days. Also, whereas virus-particle association and subsequent sedimentation has been assumed to be an important removal mechanism for viruses in WSPs, the literature review revealed a lack of evidence to confirm the validity of this assumption. The association of human adenovirus (AdV) with wastewater particles was assessed in five full-scale wastewater treatment systems in Bolivia, Brazil, and the United States (two with only WSPs, two with a UASB reactor and WSPs, and one with only UASB reactors). A mesocosm study was also conducted with WSP water from one of the full-scale systems, and some samples were also analyzed for pepper mild mottle virus (PMMoV), F+ coliphage, culturable enterovirus (EV), norovirus (NoV), and rotavirus (RV). Results indicate that WSPs and UASB reactors affect virus-particle associations in different ways, which may differ for different viruses. In UASB reactor effluent, PMMoV was more associated with particles <180 >µm, showed no indication of settling in subsequent ponds, and appeared to degrade in pond sediments after 5 days. In contrast, AdV in UASB reactor effluent was associated with small and large particles, and in subsequent ponds, particle-associated AdV showed evidence of possible settling or more rapid decay at the water surface. AdV and culturable EV were also more volumetrically-concentrated in UASB reactor sludge than they were in untreated sewage, WSP water, UASB effluent, and WSP sediments, indicating that the reactors may cause these viruses to become entrapped and concentrated in granular sludge. Some viruses may be removed in the sludge, but others exit the reactors in solution and attached to particles. The resuspension of pellets from centrifuged UASB reactor sludge samples in an eluant buffer indicated reversible AdV association with granular sludge, but some associations with particles in solution may not be reversible. The fate and transport of pathogens and fecal indicators was assessed in Bolivia for two WSP systems with direct reuse for irrigation, and one on-farm RBF system used to treat surface water polluted by untreated sewage. In the WSP systems, despite HRTs of 10 days, pathogen and fecal indicator removal was generally ≤1-log10, possibly due to overloading and short-circuiting from sludge accumulation. The RBF system provided removals on the order of 2-log10 for protozoan parasites, 3-log10 or more for viruses, and 4-log10 or more for bacteria. The use of RBF also reduced cumulative estimated health burdens associated with irrigated lettuce. Irrigation of lettuce with untreated river water caused an estimated disease burden that represents 37% of the existing burden from acute diarrhea in Bolivia; when RBF was used, this decreased to only 1.1%, which is not epidemiologically-significant, and complies with the World Health Organization guidelines. Ratios of concentrations of microorganisms in irrigation water to their respective concentrations in soil or crops were calculated, to assess transfer from irrigation water to soil or crops. These ratios (with units mL g-1) were generally < 0.1 mL g-1 for coliphage, between 1 and 100 mL g-1 for Giardia and Cryptosporidium, and generally between 100 and 1,000 mL g-1 for helminth eggs. Higher ratios could indicate more efficient transfer from water to soil or crops, longer persistence in soil or on crops, or slower leaching away from soil or crops. The results from this research demonstrate that pathogen removal in full-scale natural wastewater treatment systems happens via complex mechanisms that vary with respect to pathogen type, treatment systems configuration, and other environmental and operational parameters. Future research and innovation efforts should focus on the use of a combination of natural and non-mechanized technologies, surface-flow systems (e.g., WSPs) and subsurface systems (e.g., RBF), applied at both semi-centralized (e.g., wastewater treatment plant) and decentralized levels (e.g., on farms), to evaluate how this affects the efficiency and resiliency of pathogen removal. Also, future research is needed to further elucidate reasons for the observed differences in virus-particle associations in natural wastewater treatment systems.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / We study the richness and the spatial distribution of anuran amphibians recorded in Parque Estadual do Turvo (PET), the largest remnant of Mesophytic Semideciduous Forest in the state of Rio Grande do Sul, Brazil. In this study we (1) describe the composition of community of amphibians in PET, (2) compare the composition of species with those recorded in other localities of Seasonal Forests, testing the hypothesis that localities nearest the Misiones Nucleus support the current proposal of a new phytogeographic unit, known as Seasonal Rain Forest Region , and (3) we tested if the occurrence of breeding pond anurans differed from a null model of random placement, as well as we hypothesized that the environmental heterogeneity and spatial distribution of ponds influences the structure of anuran communities in southern Brazil. The species inventory was carried out using complementary sampling techniques (surveys at breeding sites, casual encounters, pitfall traps and search at scientific collections). To check the spatial distribution, we monitored 14 ponds with variable heterogeneity. We recorded 32 species of amphibians in the Park area, belonging to two orders: Anura, 30 native and one exotic species, and Gymnophiona, one species. The analysis of similarity among the localities of seasonal forests evidenced three groups with similarity of 45%: the former group was composed by localities of southeast and central-western Brazil, the second group was composed by southern localities, and the third group was composed by localities of the transition area with the Atlantic Forest sensu stricto. The second group supports the proposal of a new phytogeographic unit, known as 'Tropical Seasonal Forests Region'. We recorded 15 anuran species at the monitored ponds, and the species occurrence was clearly not random, corroborating our hypothesis that the anuran composition of species is influenced by environmental heterogeneity. The main descriptors of pond heterogeneity correlated with abundance of anuran species were area, depth, hydroperiod, percentage of vegetation cover on water surface, and distance of pond in relation to the nearest Park edges. The community structure of anurans was not affected by the geographical distribution of ponds. The results of the present study demonstrate that the heterogeneity of water bodies is a strong regulator of community structure of breeding pond amphibians and this information has implications for conservation strategies of Neotropical Austral anurans. / Estudamos a riqueza e a distribuição espacial da anurofauna registrada no Parque Estadual do Turvo (PET), maior remanescente de Floresta Estacional Semidecidual do estado do Rio Grande do Sul, Brasil. Nesse trabalho, (1) descrevemos a composição da comunidade de anuros do PET, (2) comparamos a composição da anurofauna com a de outras localidades de Florestas Estacionais, testando a hipótese de que as localidades próximas ao Núcleo Misiones corroboram a nova unidade fitogeográfica, conhecida como Região das Florestas Tropicais Sazonais , e (3), testamos se a ocorrência de espécies de anuros em poças é diferente de um modelo nulo de distribuição randômica, hipotetizando que a heterogeneidade ambiental e a distribuição espacial das poças têm influência sobre a estrutura das comunidades de anuros no sul do Brasil. Para o inventariamento das espécies foram empregadas diferentes técnicas (amostragens em sítios de reprodução, encontros ocasionais, armadilhas de interceptação e queda e consulta a coleções científicas). Para verificar a distribuição espacial, monitoramos 14 poças com heterogeneidade ambiental variável. Foram registradas 32 espécies de anfíbios no Parque e arredores, pertencentes a duas ordens: Anura, 30 espécies nativas e uma exótica e Gymnophiona, uma espécie. A análise de similaridade entre as localidades de Florestas Estacionais apresentou a formação de três grupos com 45% de similaridade entre eles: o primeiro grupo composto pelas localidades do sudeste e centro-oeste, o segundo grupo composto pelas localidades do sul e o terceiro grupo pelas localidades da porção de transição com a Floresta Atlântica sensu stricto. A formação do segundo grupo corrobora a proposta de uma nova unidade fitogeográfica, conhecida como Região das Florestas Tropicais Sazonais . Foram registradas 15 espécies de anuros nas poças, e sua distribuição foi claramente não randômica, corroborando a nossa hipótese de que a composição das espécies é influenciada pela heterogeneidade ambiental. As principais variáveis que estão correlacionadas com a estruturação das poças são: a área, a profundidade, o hidroperíodo, a porcentagem de cobertura vegetal no espelho d água e a distância que se encontravam em relação à borda mais próxima do Parque. A estrutura das comunidades de anuros não foi influenciada pela distribuição espacial das poças. Esse resultado indica que as poças estudadas foram independentes quanto à composição da anurofauna. Os resultados do presente estudo demonstraram que a heterogeneidade dos corpos d água é uma forte reguladora da estrutura de comunidades de anfíbios anuros e essa informação tem implicações para estratégias de conservação da anurofauna Neotropical Austral.

In urban areas, stormwater management ponds (SWPs) are built to mitigate polluted runoff. Although these ponds are increasing in numbers, their ecology is not well understood. Physical and chemical characteristics of 17 SWPs in the City of Ottawa were measured to determine the drivers of phytoplankton biomass (Chl. a) and primary production (PP). While total phosphorus was the best predictor of algal biomass in the ponds (as in lakes), the imperviousness of the catchment could also predict Chl. a. Planktonic PP in two ponds measured seasonally was more closely related to water residence time than to nutrient concentrations with rates approaching at times the theoretical maximum for aquatic systems. In one pond, whole ecosystem metabolism, estimated using diel changes in dissolved oxygen and δ18O-O2, suggested that these hypereutrophic systems were net sinks for carbon in the summer but likely sources to the atmosphere at other times of the year.

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Eutrophication in aquaculture ponds is one of the major issues related to both the environment and the health of consumers. This study has selected and conducted a water-quality survey of nine freshwater aquaculture ponds in Ho Chi Minh City. The empirical results showed that these ponds were seriously polluted with COD and BOD5 whose values did not meet the B2 column of the Vietnamese National Technical Regulation on Surface Water Quality (QCVN 08-MT:2015/BTNMT). On the other hand, most N-NH4+ and N-NO2- concentrations in the ponds met the threshold value of B2 column. The values of the chlorophyll-a are greater than 10 μg/L, indicating that investigated ponds are in a state of eutrophication. In addition, the results of the TSI calculations showed that most of the sites that are in hypereutrophication state and phosphorus is identified as the eutrophication limit factor in these sites. / Phú dưỡng hóa nguồn nước nuôi trồng thủy sản là một trong các vấn đề lớn liên quan đến cả môi trường và sức khỏe người tiêu dùng. Nghiên cứu này đã lựa chọn và tiến hành khảo sát chất lượng nước của chín ao hồ nuôi thủy sản trên địa bàn thành phố Hồ Chí Minh. Kết quả phân tích cho thấy các ao hồ trên bị ô nhiễm hữu cơ nặng với thông số COD và BOD5 đều không đạt chuẩn B2 theo quy chuẩn kỹ thuật quốc gia về chất lượng nước mặt (QCVN 08-MT:2015/BTNMT). Về mặt ô nhiễm các chất dinh dưỡng, nồng độ N-NH4+ và N-NO2- đa số chỉ thỏa mãn loại B2, thậm chí vượt ngưỡng quy định của cột B2. Các giá trị của thông số chlorophyll-a đều lớn hơn 10 μg/L, chứng tỏ các ao hồ khảo sát đều đang trong tình trạng phú dưỡng. Thêm vào đó, kết quả tính toán chỉ số TSI cho thấy hầu hết các vị trí nghiên cứu đang ở trạng thái siêu phú dưỡng và photpho được xác định là yếu tố giới hạn sự phú dưỡng của các vị trí khảo sát nêu trên.

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Thesis (MScConsEcol (Conservation Ecology and Entomology))--University of Stellenbosc, 2007. / Freshwater insect species and their host ecosystems are widely threatened, particularly within agricultural and urban landscapes of Mediterranean areas, including that of the Western Cape Province, South Africa. The study here determined the biodiversity value of nineteen artificial ponds (temporary and permanent) and two river margin sites in the Cape Floristic Region (CFR). The aim was to determine aquatic beetle and bug abundance and species richness in these ponds, a topic which has been hardly explored in South Africa. Sites were sampled from September 2005 to September 2006. A total of 18 677 aquatic beetle and bug individuals were sampled, representing 43 genera (28 beetle and 15 bug genera), 64 species (44 aquatic beetle and 20 bug species). Different pond types had distinct species assemblages. The associated physico-chemical characteristics of these sites were also investigated. The key environmental variable affecting aquatic beetle and bug distribution was naturalness (no human and environmental impact on waterbody). The results showed that the most important determinant of aquatic beetle and bug species richness across all sites was emergent macrophytes, such as Typha capensis and Persicaria decipiens. Artificial ponds in the CFR clearly increase the area of occupancy for insects, and therefore play a major role in conserving them. This is especially so when the ponds are at moderate temperatures (i.e. 19º C). Although all ponds contributed to the aquatic beetle and bug diversity in the region, they differed in relative value, depending on the combination of environmental variables affecting each pond.

From the Proceedings of the 1974 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona Academy of Science - April 19-20, 1974, Flagstaff, Arizona / This study attempts to determine the water quality changes in stock tanks and what factors are instrumental in the changes, and to assess the effects of the changes. Algal growth was the most prominent change taking place in the tanks with time. Little change in the water chemistry was noted until just before the tanks dried up. As algae died, ions tied up by the algae were released to the water, causing an increase in concentration of many of the nutrients. In order to determine the impact of various factors on algal growth, the data from eight stock tanks were analyzed by stepwise linear regression. Although 20 variables were used in the complete analysis, six variables were associated with 56.3 percent of the variance: time (since first sampling), total n, potassium, pH, inflow (recharge to the tanks), and hco3 concentration. Time and total n explained 51.3 percent of the variance, and potassium increased the variance to 52.8 percent. The pH reversed the relative positions of time and total n, with total n becoming dominant. The last two factors, inflow and hco3 were negative (resulting in a decrease in algal population) and increased the coefficient of variance to 56.3 percent.