The Natural History of Slapton Ley Nature Reserve XVIII: nitrogen and phosphorus losses from the catchment - an export coefficient modelling approach

Nitrogen and phosphorus losses from the catchment of Slapton Ley, a small coastal lake in SW England, were calculated using an adaptation of a model developed by Jorgensen (1980). A detailed survey of the catchment revealed that its land use is dominated by both permanent and temporary grassland (respectively 38 and 32% of its total area), and that the remainder is made up of the cultivation of cereals and field vegetables, and market gardening. Livestock numbers in the catchment constitute ca. 6600 head of cattle, 10,000 sheep, 590 pigs, 1700 poultry and 58 horses. The permanent human population of the area is ca. 2000, served by two small gravity-fed sewage treatment works (STWs). Inputs to, and losses from, farmland in the catchment were computed using Jorgensen’s model, and coefficients derived from the data of Cooke (1976), Gostick (1982), Rast and Lee (1983) and Vollenweider (1968). Allowing for outputs from STWs, the total annual external load of N and P upon Slapton Ley is 160 t (35 kg ha-1) a-1 N, and 4.8 t (1.05 kg ha-1) a-1 P. Accordingly to Vollenweider (1968, 1975), such loadings exceed OECD permissible level by a factor of ca. 50 in the case of N, and ca. 5 in that of P. In order to reduce nutrient loads, attention would need to be paid to both STW and agricultural sources.

Nitrogen speciation and phosphorus fractionation dynamics in a lowland chalk catchment

A detailed analysis of temporal and spatial trends in nitrogen (N) speciation and phosphorus (P) fractionation in the Wylye, a lowland Chalk sub-catchment of the Hampshire Avon, UK is presented, identifying the sources contributing to nutrient enrichment, and temporal variability in the fractionation of nutrients in transit from headwaters to lower reaches of the river. Samples were collected weekly from ten monitoring stations with daily sampling at three further sites over one year, and monthly inorganic N and total reactive P (TRP) concentrations at three of the ten weekly monitoring stations over a ten year period are also presented. The data indicate significant daily and seasonal variation in nutrient fractionation in the water column, resulting from plant uptake of dissolved organic and inorganic nutrient fractions in the summer months, increased delivery of both N and P from diffuse sources in the autumn to winter period and during high flow events, and lack of dilution of point source discharges to the Wylye from septic tank, small package Sewage Treatment Works (STW) and urban Waste Water Treatment Works (WwTW) during the summer low flow period. Weekly data show that contributing source areas vary along the river with headwater N and P strongly influenced by diffuse inorganic N and particulate P fluxes, and SRP and organic-rich point source contributions from STW and WwTW having a greater influence in the lower reaches. Long-term data show a decrease in TRP concentrations at all three monitoring stations, with the most pronounced decrease occurring downstream from Warminster WwTW, following the introduction of P stripping at the works in 2001. Inorganic N demonstrates no statistically significant change over the ten year period of record in the rural headwaters, but an increase in the lower reaches downstream from the WwTW which may be due to urban expansion in the lower catchment.

The sources of phosphorus in the waters of Great Britain

Total phosphorus (TP) and soluble reactive phosphorus (SRP) loads to watercourses of the River Basin Districts (RBDs) of Great Britain (GB) were estimated using inventories of industrial P loads and estimates of P loads from sewage treatment works and diffuse P loads calculated using region-specific export coefficients for particular land cover classes combined with census data for agricultural stocking densities and human populations. The TP load to GB waters was estimated to be 60 kt yr(-1), of which households contributed 73, agriculture contributed 20, industry contributed 3, and 4 came from background sources. The SRP load to GB waters was estimated to be 47 kt yr(-1), of which households contributed 78, agriculture contributed 13, industry contributed 4, and 6 came from background Sources. The 'average' area-normalized TP and SRP loads to GB waters approximated 2.4 kg ha(-1) yr(-1) and 1.8 kg ha(-1) yr(-1), respectively. A consideration of uncertainties in the data contributing to these estimates suggested that the TP load to GB waters might lie between 33 and 68 kt yr(-1), with agriculture contributing between 10 and 28 of the TP load. These estimates are consistent with recent appraisals of annual TP and SRP loads to GB coastal waters and area-normalized TP loads from their catchments. Estimates of the contributions of RBDs to these P loads were consistent with the geographical distribution of P concentrations in GB rivers and recent assessments of surface waters at risk from P Pollution.

Characterising phosphorus and nitrate inputs to a rural river using high-frequency concentration-flow relationships

The total reactive phosphorus (TRP) and nitrate concentrations of the River Enborne, southern England, were monitored at hourly interval between January 2010 and December 2011. The relationships between these high-frequency nutrient concentration signals and flow were used to infer changes in nutrient source and dynamics through the annual cycle and each individual storm event, by studying hysteresis patterns. TRP concentrations exhibited strong dilution patterns with increasing flow, and predominantly clockwise hysteresis through storm events. Despite the Enborne catchment being relatively rural for southern England, TRP inputs were dominated by constant, non-rain-related inputs from sewage treatment works (STW) for the majority of the year, producing the highest phosphorus concentrations through the spring–summer growing season. At higher river flows, the majority of the TRP load was derived from within-channel remobilisation of phosphorus from the bed sediment, much of which was also derived from STW inputs. Therefore, future phosphorus mitigation measures should focus on STW improvements. Agricultural diffuse TRP inputs were only evident during storms in the May of each year, probably relating to manure application to land. The nitrate concentration–flow relationship produced a series of dilution curves, indicating major inputs from groundwater and to a lesser extent STW. Significant diffuse agricultural inputs with anticlockwise hysteresis trajectories were observed during the first major storms of the winter period. The simultaneous investigation of high-frequency time series data, concentration–flow relationships and hysteresis behaviour through multiple storms for both phosphorus and nitrate offers a simple and innovative approach for providing new insights into nutrient sources and dynamics.

High-frequency water quality monitoring in an urban catchment: hydrochemical dynamics, primary production and implications for the Water Framework Directive

This paper describes the hydrochemistry of a lowland, urbanised river-system, The Cut in England, using in situ sub-daily sampling. The Cut receives effluent discharges from four major sewage treatment works serving around 190,000 people. These discharges consist largely of treated water, originally abstracted from the River Thames and returned via the water supply network, substantially increasing the natural flow. The hourly water quality data were supplemented by weekly manual sampling with laboratory analysis to check the hourly data and measure further determinands. Mean phosphorus and nitrate concentrations were very high, breaching standards set by EU legislation. Though 56% of the catchment area is agricultural, the hydrochemical dynamics were significantly impacted by effluent discharges which accounted for approximately 50% of the annual P catchment input loads and, on average, 59% of river flow at the monitoring point. Diurnal dissolved oxygen data demonstrated high in-stream productivity. From a comparison of high frequency and conventional monitoring data, it is inferred that much of the primary production was dominated by benthic algae, largely diatoms. Despite the high productivity and nutrient concentrations, the river water did not become anoxic and major phytoplankton blooms were not observed. The strong diurnal and annual variation observed showed that assessments of water quality made under the Water Framework Directive (WFD) are sensitive to the time and season of sampling. It is recommended that specific sampling time windows be specified for each determinand, and that WFD targets should be applied in combination to help identify periods of greatest ecological risk. This article is protected by copyright. All rights reserved.

Land use, water quality and ecological responses in Lake Colac – trends from Australia

Purpose - Recently, Colac Otway Shire in Australia released its management plan for Lake Colac, claiming over-enrichment of the lake with nutrients and degraded water quality. This paper aims to investigate these claims by establishing a correlation between key water and ecological indicators and land uses.

Design/methodology/approach - Examines the correlation between impairment and stressors in Lake Colac. This was achieved by identifying the likely sources of pollutants into Lake Colac; identifying any existing monitoring program; and characterizing the water and sediment inputs. The likely impacts of increased nutrients and sediment levels on indigenous flora and fauna were also examined. The use of meiofauna (very small benthic metazoan animals) was investigated as an indicator of degraded sites. Plankton diversity as a measure of water health was also assessed.

Findings - Water quality in Lake Colac was found to vary both temporally and spatially, and exhibited low attainment against acceptable trigger values/objectives. At current levels the lake can be classified as poorly degraded. Likely sources of pollution were identified to be related to land uses in the catchments. The biota of the lake, investigated at four study sites, yielded a sparse, benthic macrofaunal assemblage that was dominated by oligochaetes. In contrast, an abundant and taxonomically diverse meiofaunal assemblage was noted. Future meiofaunal analyses are likely to resolve suitable biotic indicator species of free-living nematodes in response to land use and waterway threats specified in the study. Originality value - This work will provide a better understanding of integrated environmental systems to enable development of best management practices, thus transforming the way the land and water are used in the future. Following the present work, other key water and ecological indicators (increased dispersion and dominance of biological species) at five additional sites were studied. Alternative management options for the effluent generated at Colac Sewage Treatment Plant and possible ecological effects of each option were also evaluated. More recently, a sediment characterization study was also carried out at sensitive sites representative of locations where build up of sediments and algae outbreaks are reported. This will enable classification of sediment and evaluation of dredging options.

Heavy metal accumulation in soils at three field sites subject to effluent irrigation

Three field sites were chosen to study the environmental assimilative capacity of heavy metals in soil. These sites were the Werribee Farm and the Myome Farm in Australia and Shenyang Zhangshi Irrigation Area in China. The Werribee Farm and the Shenyang Zhangshi Irrigation Area received sewage treatment and application on land for a long time. The Myome farm is an experimental site in which investigations on land application of municipal wastewater on water repellent soils is currently being trailed. Heavy metal contamination, in particular Cr, Cu and Zn, in the Land Filtration soil of Werribee Farm was widespread. More than a century of sewage irrigation has occurred in the Werribee Farm. The temporal distribution pattern of heavy metals (Cd, Cr, Cu, Ni, Pb and Zn) in the soil at this site follow an exponential trend with time and the spatial distribution pattern of accumulation of heavy metals in different paddocks correlates with the number of years of sewage irrigation at that site in the Farm. Extensive sewage irrigation at Shenyang Zhangshi Irrigation Area resulted in significant Cd pollution in soil-plant (rice) system and poses a significant threat to the health of local people. Even after eight years since cessation of sewage irrigation, the bioavailable fractions of Cd in the soil as analyzed by sequential extraction techniques were very high thus illustrating long-term persistence. The simultaneous competitive adsorption of metals in water repellent soils (at Myome Farm in South Australia) was studied. In the competitive situation, Cr, Pb and Cu are the heavy metal cations more strongly adsorbed by the soil, whereas Cd, Ni and Zn are the least adsorbed. The increase in Freundlich adsorption capacity by clay amendment suggested that clayed soils are capable sorption of higher heavy metal loadings compared to the non-clayed water repellent soil, which is more vulnerable to heavy metal inputs. A simple model of environmental assimilative capacity is proposed. The results of comparison of the three field sites shows that the Werribee Farm has a higher environmental assimilative capacity of heavy metals in soil than the soils at Shenyang Zhangshi Irrigation Area and Myome Farm, however heavy metal contamination at Werribee Farm is still a concern. The model of environmental assimilative capacity of heavy metals in soil is an effective tool to assist management of effluent applied land irrigation systems and can be used to better design environmental engineering systems.

A history of wastewater irrigation in Melbourne, Australia

Reclamation of wastewater for irrigation has had an important role to play in Melbourne’s struggle to manage water resources as effectively as possible. Rapid growth within the first few years of the founding of the city led to a sanitary crisis, which provided the impetus for the construction of a large sewerage system. Interest in using the effluent from sewage treatment plants for irrigation gained attention in the late 1970s, but despite some activity in the early 1980s, it was not until 2005 that large-scale wastewater irrigation schemes became a reality. Successful to a degree, there have also been problems, and the future viability of one large irrigation scheme for commercial vegetable production is threatened by high salt concentrations in the treated wastewater. Greywater irrigation at the household level has also become commonplace in Melbourne over the last decade, but it is difficult to regulate and the health risks urgently need to be quantified. More recently, several third-pipe schemes, where treated wastewater is reticulated to households, have been commissioned with plans for many more, and treated stormwater is growing in popularity, particularly for irrigation of public open spaces.

Comportamento do reator seqüencial em batelada (RSB) sob estado estacionário dinâmico utilizando idade do lodo como parâmetro de controle operacional

O reator seqüencial em batelada (RSB) é uma variante de lodos ativados capaz de promover a remoção da matéria orgânica, a remoção dos nutrientes e a separação da fase sólida da líquida em uma unidade. A valorização das áreas urbanas, a carência de tratamento terciário e a crescente necessidade de redução nas dimensões de estações de tratamento de esgoto devem impulsionar o desenvolvimento de pesquisas sobre RSB em curto espaço de tempo. A partir deste cenário, o presente trabalho teve como objetivo modelar o comportamento do reator seqüencial em batelada a partir da teoria desenvolvida por Marais e colaboradores. Dentro deste contexto, a cinética de oxidação dos compostos orgânicos e do nitrogênio na forma amoniacal foi descrita e modelada. O trabalho experimental foi realizado em duas escalas: bancada e piloto. O experimento em escala de bancada foi dividido em duas fases. Foram utilizados dois RSBs e um sistema de fluxo contínuo. Um reator seqüencial em batelada (RSB1) foi operado com idade de lodo. O outro reator em batelada (RSB2) foi operado em função da relação F/M e o sistema de fluxo contínuo (FC1) por idade de lodo. Estes reatores foram utilizados como controle no monitoramento do RSB1 Na primeira fase, os três sistemas removeram apenas matéria orgânica. Na fase seguinte, removeram matéria orgânica e nitrogênio. A partir dos resultados obtidos em escala de bancada, foi possível concluir que o modelo desenvolvido pode ser aplicado ao reator seqüencial em batelada operando com idade de lodo, permitindo determinar a qualidade do efluente, a produção de lodo e o consumo de oxidante. Além disso, foi possível descrever o comportamento da taxa de consumo de oxigênio em função da oxidação da matéria orgânica biodegradável e da oxidação do nitrogênio na forma amoniacal. O reator seqüencial em batelada operado com idade de lodo (RSB1) alcançou remoção média de matéria orgânica de 90 % nas idades de lodo de 30, 20, 10 e 5 dias. A remoção média de nitrogênio mais elevada foi obtida na idade de lodo de 20 dias e atingiu 87 %. Nas demais idades de lodo a remoção média de nitrogênio variou entre 79 e 42 %. A modelagem do comportamento do reator seqüencial em batelada resultou numa proposta de metodologia para o dimensionamento que tem como finalidade abolir critérios obsoletos e inadequados para o dimensionamento de lodos ativados em batelada No experimento em escala piloto, foram utilizados um reator seqüencial em batelada, denominado RSB, e um sistema de fluxo contínuo com a configuração Bardenpho, denominado FC. Os sistemas de lodos ativados sob investigação foram monitorados em duas idades de lodo: 30 e 10 dias. Os dados do experimento em escala piloto mostraram que os processos físico-químicos e biológicos envolvidos na remoção de matéria orgânica e nitrogênio no RSB foram mais eficientes do que no Bardenpho quando trataram o mesmo esgoto doméstico e foram submetidos às mesmas condições operacionais. No RSB, obteve-se 88 e 89 % de remoção de matéria orgânica nas idades de lodo de 10 e 30 dias, respectivamente. Nesta seqüência das idades de lodo, a eficiência do Bardenpho caiu de 87 para 76 %. O sistema de fluxo contínuo removeu 66 e 52 % do nitrogênio total afluente nas idades de lodo de 10 e 30 dias, respectivamente. A eficiência do RSB na remoção de nitrogênio foi determinada apenas na idade de lodo de 10 dias e alcançou 69 %. A partir dos resultados obtidos em escala de bancada e piloto, constata-se que o reator seqüencial em batelada operando com idade de lodo pode ser utilizado no tratamento de esgoto doméstico e obter eficiência na remoção de matéria orgânica e nitrogênio igual ou superior ao sistema de fluxo contínuo.

A utilização de serviços odontológicos entre crianças e fatores associados em Sobral, Ceará, Brasil

NORO, L. R. A. et al. A utilização de serviços odontológicos entre crianças e fatores associados em Sobral, Ceará, Brasil. Cad. Saúde Pública, v. 24, n. 7, p. 1509-1516. 2008. ISSN 0102-311X.

Diagnóstico ecotoxicológico dos efluentes lançados no complexo estuarino do Jundiaí/Potengi, Natal/RN

Untreated effluents that reach surface water affect the aquatic life and humans. This study aimed to evaluate the wastewater s toxicity (municipal, industrial and shrimp pond effluents) released in the Estuarine Complex of Jundiaí- Potengi, Natal/RN, through chronic quantitative e qualitative toxicity tests using the test organism Mysidopsis Juniae, CRUSTACEA, MYSIDACEA (Silva, 1979). For this, a new methodology for viewing chronic effects on organisms of M. juniae was used (only renewal), based on another existing methodology to another testorganism very similar to M. Juniae, the M. Bahia (daily renewal).Toxicity tests 7 days duration were used for detecting effects on the survival and fecundity in M. juniae. Lethal Concentration 50% (LC50%) was determined by the Trimmed Spearman-Karber; Inhibition Concentration 50% (IC50%) in fecundity was determined by Linear Interpolation. ANOVA (One Way) tests (p = 0.05) were used to determinate the No Observed Effect Concentration (NOEC) and Low Observed Effect Concentration (LOEC). Effluents flows were measured and the toxic load of the effluents was estimated. Multivariate analysis - Principal Component Analysis (PCA) and Correspondence Analysis (CA) - identified the physic-chemical parameters better explain the patterns of toxicity found in survival and fecundity of M. juniae. We verified the feasibility of applying the only renewal system in chronic tests with M. Juniae. Most efluentes proved toxic on the survival and fecundity of M. Juniae, except for some shrimp pond effluents. The most toxic effluent was ETE Lagoa Aerada (LC50, 6.24%; IC50, 4.82%), ETE Quintas (LC50, 5.85%), Giselda Trigueiro Hospital (LC50, 2.05%), CLAN (LC50, 2.14%) and COTEMINAS (LC50, IC50 and 38.51%, 6.94%). The greatest toxic load was originated from ETE inefficient high flow effluents, textile effluents and CLAN. The organic load was related to the toxic effects of wastewater and hospital effluents in survival of M. Juniae, as well as heavy metals, total residual chlorine and phenols. In industrial effluents was found relationship between toxicity and organic load, phenols, oils and greases and benzene. The effects on fertility were related, in turn, with chlorine and heavy metals. Toxicity tests using other organisms of different trophic levels, as well as analysis of sediment toxicity are recommended to confirm the patterns found with M. Juniae. However, the results indicate the necessity for implementation and improvement of sewage treatment systems affluent to the Potengi s estuary

Caracterização da água da microbacia do córrego rico avaliada pelo índice de qualidade de água e de estado trófico

A avaliação do índice de qualidade da água (IQA) e do índice de estado trófico médio (IETm) pode subsidiar a formulação de planos de manejo e gestão de sistemas aquáticos. Neste trabalho, foi avaliada a qualidade da água da microbacia do Córrego Rico, que abastece a cidade de Jaboticabal (SP), utilizando o IQA e IETm. As amostragens de água foram realizadas entre setembro-2007 e agosto-2008, em três pontos: a) em uma das nascentes; b) após a Estação de Tratamento de Esgoto de Monte Alto, e c) na captação de água para abastecimento público de Jaboticabal. As amostras foram analisadas quanto aos parâmetros físicos, químicos e microbiológicos: temperatura, oxigênio dissolvido, pH, DBO5, nitrogênio total, fósforo total, turbidez, resíduo total, ortofosfato, clorofila-a e Escherichia coli. de acordo com os resultados obtidos, concluiu-se que: a) as atividades antrópicas às margens do Córrego Rico reduzem a qualidade de sua água, durante os diferentes períodos do ano; b) os valores médios de IQA nos três pontos analisados apresentaram relação direta com os valores médios de IETm, porém ocorreu maior discriminação da qualidade da água pelo IETm, identificando diferentes graus de trofia para os pontos e períodos de amostragens; c) o IQA apresentou melhor diferenciação da qualidade da água entre pontos no período seco e o IETm diferenciou melhor no período chuvoso; d) o processo de autodepuração e/ou a confluência do Córrego Tijuco com o Córrego Rico contribuem para melhor qualidade da água, tornando-a adequada ao abastecimento urbano após tratamento convencional.

Efeitos da aplicação de efluente de tratamento de esgoto na fertilidade do solo e produtividade de pepino sob irrigação subsuperficial

O experimento foi conduzido com o objetivo de avaliar técnicas para a aplicação de águas residuárias na agricultura, proporcionando melhor reutilização de água, recurso natural atualmente escasso e muito mal disponibilizado. Utilizou-se da cultura de pepino (Cucumis sativus L.) em estufa, com oito parcelas irrigadas com efluentes de tratamento de esgoto residencial e oito parcelas irrigadas com água tratada e distribuída pela SABESP (tratamento-testemunha), ambas abastecidas por sistema de irrigação subsuperficial, avaliando-se a produção média por planta, a fertilidade do solo e a disposição de nutrientes na água do solo. Nas análises do solo, verificaram-se maiores teores de P, K e CTC no solo irrigado com efluentes. Nesse mesmo tratamento, constataram-se os maiores teores de N, nitrato, Ca, Mg, Zn e S para as análises da água retida na matriz do solo. Quanto à produção total média por planta, as parcelas irrigadas com efluente apresentaram 2.769,6 g de matéria fresca, superior aos 1.968,6 g verificados no tratamento-testemunha, demonstrando a importância da utilização de efluente de esgoto para o fornecimento de nutrientes e aumento de produtividade.

Dinâmica de Sedimentação de Lodo em Lagoas de Estabilização

Stabilization ponds are an effective sewage treatment alternative for the climatic conditions prevailing in Brazil. In the present work, a primary facultative pond was studied, in the city of Natal, Rio Grande do Norte, Northeast Brazil. The aim of this study was to evaluate the sedimentation dynamics in the facultative pond. The pond was divided in three section or zones along its length starting from the inlet end namely A1, A2 and A3. The research was accomplished in three phases. In the first the mapping of the sludge layer was done, sludge core samples were also collected for analysis for total, fixed and volatile solids and the depth of the sludge layer was determined using a portable echo sounder. In the second solids sedimentation rates were measured using traps placed in the inlet and outlet zones and in the third phase resuspension sludge was evaluate using a tracer. The amount accumulated sludge since the start operation was 13.583 m3. The sedimentation constant averages changed between 0.93 to 2.94 and 3.90 to 5.80 for the depths of 0.5 and 1.0 m respectively. The relationship between volatile and fixed solids (SV/SF) increased along the pond. The removal efficiencies were 52.12%, 36.09%, and 37.50% for BOD, COD and SS, respectively. The sludge accumulation model proposed had a good adjustment with 0.17 m3/hab.year rate. The results presented here demonstrated that the wind had a direct influence on the sedimentation of solids in this pond affecting the efficiency and sludge accumulation