Motionless of snail Hydrobia ulvae (Pennant) as response to sediment toxicity and its consequences for the post-exposure feeding

Post-exposure feeding and motionless may be useful endpoints for assessing toxicity. The present study aimed to examine (i) the immobility of the estuarine snail Hydrobia ulvae resulting from short-term exposure to copper-spiked sediment, and subsequently, (ii) the potential application of post-exposure feeding (indirectly measured as pellets excreted) as an ecotoxicological response associated with motionlessness. Mobility and post-exposure feeding were influenced by copper contamination. Motionless was noticeable above the concentration of 200 μg Cu g-1, where 40% of the organisms were inactive. Practically all the organisms remained active at the two lowest concentrations: 40 (control) and 60 μg Cu g-1. For 400 and 800 μg Cu g-1 the motionless was generally higher than 50%. Mortality higher than 25% was observed at 200, 400 and 800 μg Cu g-1, with values of 27, 40 and 60%, respectively. The feeding inhibition values showed an increasing inhibition from 20% at the lowest concentration (60 μg Cu g-1), up to 59% at 400 μg Cu g-1; at concentration of 800 μg Cu g-1, although the physical activity inhibition had reached 67%, the post-exposure feeding was 1.5 higher in relation to the control. Probably, the starvation period due to motionless during exposure seems to increase the post-exposure feeding and egestion when food was provided; alternatively, increased pellet production could also indicate a detoxification process

Reconnaissance of Sediment-Phosphorus Relationships in Upper Flaming Gorge Reservoir

Executive Summary: A reconnaissance-level study was conducted in Flaming Gorge Reservoir, Wyoming, during the late summer of 1982 in order to determine the possible importance of the sediment sin exacerbating the blue-green algal blooms that occur in summer in the upper reservoir. Sediments can affect phytoplankton dynamics in reservoirs on an annual basis by delyaing the availability of particulate P associated with spring runoff until late summery, when the warm water temperatures and the light climate favor the growth of blue-green algae. Over the longer term, however, sediments that historically have served as a trap for part of the annual phosphous load entering the system may release some of this stored P in response to decreased P concentrations in the overlying water. The decreased concentrations may result from unusally wet water years or, more importantly from a management standpoint, from restoration strategies aimed at reducing inputs of P from the watershed. The resulting internal P loading can delay the anticipated recovery of a reservoir for may years, relative to the recovery rate that owuld be predicted in its absence. The study of lacustrine sediments is helpful in predicting the potential for internal P loading from a particular sediment, as well as the factors more important in controlling P releas

An integrated environmental assessment of the water and sediments from the coastal areas of Guarujá, São Paulo, Brazil: a physico-chemical, biological and ecotoxicological approach

O município de Guarujá, litoral do Estado de São Paulo, Brasil, considerado um dos principais destinos turísticos brasileiros, possui uma sub-bacia hidrográfica sob forte pressão antrópica. Isto ocorre porque embora possua uma área de drenagem de aproximadamente 143 km², cerca de 107 km² são áreas ambientalmente protegidas e, portanto, 316.000 habitantes se concentram em uma pequena fração territorial (correspondente a 36 km2). Durante o verão, quando o turismo intensifica, a população chega a duplicar. Em decorrência deste forte adensamento populacional e da ausência de planeamento urbano, Guarujá sofre há décadas com problemas socioambientais e de infraestrutura urbana, principalmente porque mais de 64.000 moradores habitam áreas de favelas (principalmente nos bairros da Enseada e do Perequê) e, portanto, não possuem saneamento básico. Desta forma, embora a rede de coleta e tratamento de esgotos municipal esteja dimensionada para uma população de 450.000 habitantes, o destino dos esgotos clandestinos destas favelas acaba sendo os 43 canais artificiais de drenagem urbana, que descarregam uma mistura complexa (composta por esgoto doméstico e carga difusa urbana) diretamente para as praias do município e, portanto, podendo comprometer a saúde pública e ambiental de Guarujá. Embora avaliar a qualidade balnear, se mostre emergencial no Guarujá, estes estudos ainda são escassos no município. Diante deste cenário, o objetivo geral desta tese foi avaliar a qualidade da água e do sedimento nos canais de drenagem urbana localizados em quatro diferentes praias do Guarujá: Tombo (certificada com Bandeira Azul), Enseada (com alta visitação turística), Perequê (habitada por uma comunidade pesqueira) e Iporanga (localizada numa unidade de conservação). Além destes quatro canais, foi investigada a coluna de água e o sedimento da zona de mistura do emissário oceânico submarino, cujo esgoto municipal passa por um tratamento preliminar em terra. Para atender a estes objetivos, amostras mensais foram obtidas no período entre outubro de 2017 a agosto de 2018, e trinta e oito variáveis ambientais selecionadas (físicas, químicas, biológicas e ecotóxicológicas), juntamente com vinte e três compostos farmacêuticos de diferentes classes terapêuticas, foram analisados utilizando testes estatísticos padrão e/ou diferentes índices de qualidade da água. Nos canais de drenagem urbana, os resultados mais expressivos obtidos desta tese, foram: (i) há evidenciais de que os canais do Guarujá são importantes veículos de transporte de poluentes convencionais e emergentes para o Oceano Atlântico Sul; (ii) áreas com déficit de saneamento (principalmente na Enseada e Perequê), juntamente com o período de maior afluência turística (verão brasileiro/período chuvoso), foram fatores que potencializaram a piora da qualidade da água; (iii) de maneira geral, a melhor qualidade da água foi registrada em Iporanga (mais de 90% em conformidade com a legislação brasileira); (iv) os canais do Tombo, Enseada e Perequê foram classificados como muito ruins (apenas 34-43% em conformidade com a legislação vigente) e, como consequência, altas concentrações das bactérias Escherichia coli e Enterococcus ssp foram detectadas nestes canais. Além disso, a presença de mastadenovírus humanos (espécies C, D e F) na Enseada e Perequê, também foram importantes descobertas, potencialmente preocupantes para a saúde pública local; (v) táxons da macrofauna bentônica, tolerantes à poluição orgânica, foram inventariados no sedimento adjacente aos canais (por exemplo, Oligochaeta, Ceratopogonidae, Chironomidae e Chironomus); (vi) dezasseis compostos farmacêuticos foram detectados, sendo que cinco deles (cafeína, acetaminofeno, diclofenaco, valsartan e losartan), indicaram riscos escológicos moderados a altos para algas, crustáceos e/ou peixes; e (vii) toda esta complexa mistura de poluentes dos canais, indicaram uma alta toxicidade aguda e crônica para os microcrustáceos Daphnia simillis e Ceriodaphnia dúbia, respectivamente. Já na descarga marinha de esgotos, os resultados mais importantes, na coluna de água, foram: (i) das trinta e três variáveis fisicoquímicas e bacteriológicas analisadas, nove não atenderam à legislação vigente e, portanto, a água foi classificada como de qualidade regular; (ii) dez compostos farmacêuticos foram detectados, sendo que três deles (cafeína, diclofenaco e acetaminofeno), indicaram riscos baixos a moderados para algas, crustáceos e/ou peixes. Já nos sedimentos, as baixas concentrações de seis metais pesados, a boa representatividade de anfípodes e poliquetas (dentre os vinte e cinco táxons bentônicos inventariados), além da ausência de toxicidade aguda para o tanaidaceo Kalliapseudes schubartii, indicaram sedimentos pouco poluídos. Com a evidência da forte interferência antrópica na qualidade da água do Guarujá, melhorias em benefício da saúde pública e da proteção dos sistemas ecológicos (fundamentadas em boas práticas internacionais e na legislação brasileira vigente) foram sugeridas, como sejam: (i) programas de educação e conscientização ambiental; (ii) programas de recolhimento de resíduos de medicamentos; (iii) manutenção de vias públicas; (iv) fiscalização das ligações clandestinas de esgotos no bairro do Tombo; (v) regularização fundiária das favelas da Enseada e do Perequê; (vi) instalação de um sistema de comporta, interceptor oceânico e barreiras de conteção nos canais de drenagem. E por fim, foi sugerida a modernização do sistema de tratamento de esgotos do município, através da instalação de um tratamento, no mínimo, com um nível secundário.The municipality of Guarujá, on the coast of the State of São Paulo, Brazil, considered one of the main tourist destinations in Brazil, has a sub-basin under strong anthropic pressure. This occurs because although it has a drainage area of approximately 143 km², about 107 km² are environmentally protected areas and, therefore, 316,000 inhabitants are concentrated in a small territorial fraction (corresponding to 36 km2). During the summer, when tourism intensifies, the population almost doubles. As a result of this high-population density and absence of urban planning, Guarujá has suffered for decades from socio-environmental and urban infrastructure problems, mainly because more than 64,000 residents live in slum areas (locally named “favelas”, mainly in the Enseada and Perequê neighbourhoods) and therefore do not have basic sanitation. Thus, although the municipal sewage collection and treatment network is sized for a population of 450,000 inhabitants, the destination of clandestine sewage from the “favelas” ends up on the 43 artificial urban drainage channels, which drain a complex mixture (composed of domestic sewage and urban diffuse load) directly to the beaches of the municipality and, therefore, may compromise the public and environmental health of Guarujá. Although the assessment of the bathing water quality is a priority in Guarujá, these studies are scarce in the municipality. In this scenario, the general objective of this thesis was to evaluate the water and sediment quality in urban drainage channels located in four different beaches of Guarujá: Tombo (Blue Flag certified), Enseada (high tourist visitation), Perequê (inhabited by a fishing community) and Iporanga (located in a conservation unit). In addition to these four channels, the water column and the sediment of the mixing zone of the submarine ocean outfall, whose municipal sewage undergoes preliminary treatment on land, were investigated. To meet these objectives, monthly samples were obtained during the period from October 2017 to August 2018, and thirty-eight selected environmental variables (physical, chemical, biological and ecotoxicological), together with the twenty-three pharmaceutical compounds of different therapeutic classes, were analysed using standard statistical tests and/or different water quality indices. In the urban drainage channels, the most expressive results obtained from this thesis, were: (i) there is evidence that the channels of Guarujá are important vehicles for the transport of conventional and emerging pollutants to the South Atlantic Ocean; (ii) areas with sanitation deficit (mainly in Enseada and Perequê), together with the period of greatest tourist affluence (Brazilian summer/rainy season), were factors that potentiated the worsening of water quality; (iii) in general, the best water quality was recorded at Iporanga (more than 90% of compliance with the Brazilian legislation); (iv) the Tombo, Enseada and Perequê channels were classified as very bad (only 34-43% of compliance with the current legislation) and, as a consequence, high concentrations of the bacteria Escherichia coli and Enterococcus ssp were detected in these channels. Furthermore, the presence of human mastadenovirus (species C, D and F) in Enseada and Perequê were also important findings, and raises great concern for local public health; (v) benthic macrofauna taxa, tolerant to organic pollution, were inventoried in the sediment adjacent to the channels (e.g. Oligochaeta, Ceratopogonidae, Chironomidae and Chironomus); (vi) sixteen pharmaceutical compounds were detected, five of which (caffeine, acetaminophen, diclofenac, valsartan and losartan), indicated a moderate to high ecological risks to algae, crustaceans and/or fish; and (vii) this whole complex mixture of pollutants from the channels, indicated high acute and chronic toxicity to the microcrustaceans Daphnia simillis and Ceriodaphnia dubia, respectively. As for the marine sewage discharge, the most important results, in the water column, were: (i) of the thirty-three physicochemical and bacteriological variables analysed, nine did not comply with the current legislation and, therefore, the water was classified as regular; (ii) ten pharmaceutical compounds were detected, three of them (caffeine, diclofenac and acetaminophen), indicating low to moderate risks for algae, crustaceans and/or fish. In the sediments, the low concentrations of six heavy metals, the good representation of amphipods and polychaetes (among the twenty-five benthic taxa inventoried), besides the absence of acute toxicity for the tanaidaceous Kalliapseudes schubartii, indicated slightly polluted sediments. With the evidence of the strong anthropic interference in the quality of the water of Guarujá, improvements for the benefit of public health and the protection of the ecological systems (based on good international practices and on the Brazilian legislation in force) were suggested, such as: (i) community awareness and educational programs; (ii) drug disposal programs; (iii) public road maintenance; (iv) inspection of clandestine sewage connections in the Tombo neighbourhood; (v) land regularization of the Enseada and Perequê favelas; (vi) installation of a floodgate system, ocean interceptor and containment barriers in the drainage channels. Finally, it was suggested that the municipal sewage system should be modernised by installing, at least, a secondary level of treatment.La municipalité de Guarujá, sur la côte de l'État de São Paulo, au Brésil, considérée comme l'une des principales destinations touristiques du Brésil, possède un sous-bassin soumis à une forte pression anthropique. En effet, bien qu'elle ait une zone de drainage d'environ 143 km², 107 km² sont des zones protégées sur le plan environnemental et, par conséquent, 316 000 habitants sont concentrés dans une petite fraction territoriale (correspondant à 36 km2). Pendant l'été, lorsque le tourisme s'intensifie, la population presque double. En raison de cette forte densité de la population et de l'absence de planification urbaine, Guarujá souffre depuis des décennies de problèmes socio-environnementaux et d'infrastructure urbaine, principalement parce que plus de 64 000 habitants habitent les bidonvilles (localement appelés « favelas », principalement dans les quartiers d'Enseada et de Perequê) sans aucun système sanitaire de base. Ainsi, bien que le système municipal de collecte et de traitement des eaux usées soit dimensionné pour une population de 450 000 habitants, la destination des effluents clandestines des « favelas » est les 43 canaux artificiels de drainage urbain, qui drainent un mélange complexe (composé d'eaux usées domestiques et de charge urbaine diffuse) directement vers les plages de la municipalité et, par conséquent, peuvent compromettre la santé publique et environnementale de Guarujá. Bien que l'évaluation de la qualité des eaux balnéaires soit une urgence à Guarujá, ces études sont encore rares dans la municipalité. Compte tenu de ce scénario, l'objectif général de cette thèse était d'évaluer la qualité de l'eau et des sédiments dans les canaux de drainage urbains situés sur quatre plages différentes de Guarujá: Tombo (certifié Pavillon Bleu), Enseada (forte fréquentation touristique), Perequê (habité par une communauté de pêcheurs) et Iporanga (situé dans une unité de conservation). En plus de ces quatre canaux, la colonne d'eau et les sédiments de la zone de mélange de l'émissaire sous-marin, dont les eaux usées municipales subissent un traitement préliminaire à terre, ont été étudiés. Pour atteindre ces objectifs, des échantillons mensuels ont été obtenus entre octobre 2017 et août 2018, et trente-huit variables environnementales sélectionnées (physiques, chimiques, biologiques et écotoxicologiques), ainsi que vingt-trois composés pharmaceutiques de différentes classes thérapeutiques, ont été analysés en utilisant des tests statistiques standard et/ou différents indices de qualité de l'eau. Dans les canaux de drainage urbains, les résultats les plus expressifs obtenus dans le cadre de cette thèse, ont été: (i) il est prouvé que les canaux de Guarujá sont d'importants véhicules de transport de polluants conventionnels et émergents vers l'océan Atlantique Sud; (ii) les plages présentant un déficit sanitaire (principalement à Enseada et Perequê), ainsi que la période de plus grande affluence touristique (été brésilien/saison des pluies), sont des facteurs qui ont potentialisé la détérioration de la qualité de l'eau; (iii) en général, la meilleure qualité d'eau a été enregistrée à Iporanga (plus de 90% de conformité avec la législation brésilienne); (iv) les canaux Tombo, Enseada et Perequê ont été classés comme très mauvais (seulement 34-43% de conformité avec la législation en vigueur) et, en conséquence, de fortes concentrations des bactéries Escherichia coli et Enterococcus ssp ont été détectées dans ces canaux. En outre, la présence de mastadenovirus humains (espèces C, D et F) à Enseada et Perequê a également été constatée, ce qui a suscité une grande inquiétude pour la santé publique locale; (v) des taxons de la macrofaune benthique, tolérante à la pollution organique, ont été inventoriés dans les sédiments adjacents aux canaux (par exemple Oligochaeta, Ceratopogonidae, Chironomidae et Chironomus); (vi) seize composés pharmaceutiques ont été détectés, et cinq d'entre eux (caféine, acétaminophène, diclofénac, valsartan et losartan), ont indiqué des risques escologiques modérés et élevés pour les algues, les crustacés et/ou les poissons; et (vii) tout ce mélange complexe de polluants provenant des canaux, a indiqué une toxicité aiguë et chronique élevée pour les microcrustacés Daphnia simillis et Ceriodaphnia dubia, respectivement. En ce qui concerne le rejet des eaux usées en mer, les résultats les plus importants dans la colonne d'eau ont été obtenus: (i) sur les trente-trois variables physico-chimiques et bactériologiques analysées, neuf ne répondaient pas à la législation en vigueur et, par conséquent, l'eau a été classée comme régulière; (ii) dix composés pharmaceutiques ont été détectés, dont trois (caféine, diclofénac et acétaminophène), indiquant des risques faibles et modérés pour les algues, les crustacés et/ou les poissons. Dans les sédiments, les faibles concentrations de six métaux lourds, la bonne représentation des amphipodes et des polychètes (parmi les vingt-cinq taxons benthiques inventoriés), outre l'absence de toxicité aiguë pour le tanaidacé Kalliapseudes schubartii, indiquaient des sédiments peu pollués. Compte tenu des preuves de la forte interférence anthropique dans la qualité de l'eau de Guarujá, des améliorations au profit de la santé publique et de la protection des systèmes écologiques (basées sur les bonnes pratiques internationales et sur la législation brésilienne en vigueur) ont été suggérées, parmi lesquelles : (i) programmes de sensibilisation environnementale et d'information de la communauté ; (ii) programmes de collecte des déchets médicaux; (iii) amélioration de la voie publique; (iv) surveillance des branchements clandestins d'eaux usées dans le quartier de Tombo; (v) régularisation foncière des favelas d'Enseada et de Perequê; (vi) installation d'un système de vannes, d'un intercepteur océanique et de barrières de confinement dans les canaux de drainage. Finalement, il a été suggéré de moderniser le réseau d'égouts municipal en installant, au moins, un système de traitement secondaire

Effects of maintenance dredging on the macrofauna of the water column in a turbid estuary

Many human activities in or near aquatic habitats generate alterations in their environmental conditions, which could affect the organisms that inhabit them. Maintenance dredging of navigation channels in order to allow large ships access to inland ports is one such source of disturbance. In this study, by taking multiple approaches (immediate-, short- and medium term), we analysed the effects of a maintenance dredging operation on physiochemical variables and the early life stages of fish and other macrofauna groups present in two zones of the Guadalquivir estuary with different salinity ranges (poly- and mesohaline). Most physiochemical variables were homogenized in the water column immediately after the water mass passed by the dredger, including sediment resuspension. However, this process seemed to be transient as no significant increments in the depth-averaged levels of turbidity were observed in the short- and medium-terms. Instead, metal concentrations of Cr, Fe and Zn increased in the polyhaline station. Even so, these perturbations did not appear to be severe enough to influence the macrofauna. Still, organisms can suffer direct mechanical impacts of the trailer suction. Hyperbenthic species, like Pomatoshcistus spp. or decapods, tended to decrease slightly, while pelagic species such as Engraulis encrasicolus or mysids did not, indicating that benthic organisms are usually more susceptible to high entrainment. Nonetheless, the possible effects of this disturbance were of the same order or less than those of natural ones; therefore, organisms of the macrofauna could be well adapted to cope with them.Plan Propio Universidad de Sevill

The biogeochemistry of 210Pb and 210Po in fresh waters and sediments

Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution January 1988The focus of this work was geochemical cycling of 210Pb in lakes, including the water column, sediments, and their interactions with each other. A special goal was to elucidate processes that might influence the distribution and fluxes of the radionuclide in ways that could effect 210Pb sediment dating. A mass balance for the epilimnion showed that 210Pb inputs by precipitation were matched by outputs on settling particles, indicating that direct uptake by bottom sediments was inconsequential. Below the epilimnion, vertical eddy diffusion was calculated by the heat flux gradient method including corrections for both radiant heating and heat loss to sediments. Vertical mixing was very low because of stability imparted by a steep temperature/density gradient extending right to the sediment water interface. Anoxic conditions caused remobilization of reduced iron, which reprecipitated at the oxycline and returned to the bottom via settling. 210Pb followed the same pattern except that, at the interface, it was scavenged rather than precipitated. Below the zone of precipitation, both 210Pb and iron distributions could be described by a model consisting of constant release from anoxic sediments, horizontal transport, and simple dilution in the water column. Cycling of 210Po was complicated by unidentified additional factors. A finite difference model (SEDIMIX) was used to find the combination of sedimentation and Fickian redistribution that provided the best fit to the 210Pb sediment data. Sedimentation rates were found to increase linearly with overlying water depth. The magnitude of the Fickian component of 210Pb transport was equal to calculated rates of pore water diffusive flux, which is probably more important than sediment mixing in this lake. 210Pb, 210Po, and ancillary geochemical parameters were measured on the solid fraction and pore waters of two cores taken from the deepest basin in August and September. The radionuclides were two orders of magnitude higher than in overlying water and had steep concentration gradients that could support substantial diffusive fluxes. Fe, Mn, S(II), and alkalinity did not have similar gradients. 210Pb partition coefficients ranged from 1500 to 15000, decreasing with depth, and seemed to be controlled by sorption on iron oxides. Remobilization to the water column apparently comes from a thin layer of iron-rich floc near the sediment water interface. Deeper in the cores, diffusive transport can cause redistribution of 210Pb to an extent that can affect 210Pb dating.Financial support for parts of this work has come from a National Science Foundation graduate research fellowship, a U.S. Geological Survey water resources research grant, three National Wildlife Federation environmental conservation fellowships, the Massachusetts D.W.P.C., and a Geological Society of America graduate award

Linking Management and Markets: The Northwest Atlantic Sea Herring Industry and the Case for Regional Quotas

This review and characterization of the U.S. Atlantic sea herring fishery and industry analyzes opportunities for and constraints to developing the herring resource more fully. Chapter 1 describes the herring resource, the existing fishery, and reviews current research into the international transboundary migrations of the Atlantic sea herring. Chapters 2 and 3 describe the development of the herring fishery management plan in the context of the global herring market and the management complications that arise from the transboundary migrations of the stocks. Examples of successful linkages between fisheries management and market development are described in Chapter 4 to illustrate the importance of incorporating these two elements into fisheries management plans. These management systems, largely drawn from other countries which encourage more local control and responsibility for sustaining fisheries resources, are summarized to illustrate options for inclusion in the draft U.S. Atlantic herring management plan. A proposal and justification for regional and/or community -based allocations of herring is presented in Chapter 5. This proposal is grounded in the language of the draft Atlantic sea herring management plan currently under development, and draws on examples of similar management schemes which have proved successful in linking management and marketing of fisheries resources. In order to develop a current perspective on the U.S. herring industry, a representative cross-section of industry participants was interviewed for their opinions on opportunities and constraints to further utilization of the Atlantic herring resource. Summary results of the interviews are included in relevant chapters of the paper

Vegetative Filter Strip: A Best Management Practice (Bmp) for Feedlot Runoff Pollution Control in North Dakota

Runoff from animal feeding operations is a major source of water pollution. Vegetative filter strips (VFS) are effective ways to reduce nonpoint source pollution. In this study, vegetative filter strips with different designs and in climatic and management conditions of North Dakota were evaluated. Runoff samples were collected from inflow (before entering VFS) and outflow (after exiting the VFS) locations using automatic samplers. Collected samples were analyzed for solids and nutrients. It was observed that the transport reductions by VFS were ranged from very low to up to 100%. However, soluble nutrients were not as effectively removed as sediment and sediment bound nutrients. Filter with longer length was more effective in reducing transport of sediments and nutrients. Antecedent soil moisture condition had an important effect on VFS performance. An attempt was made by varying the VFS soil pH in a broader range to investigate effect of pH on reducing transport of soluble nutrients from manure borne runoff. Soil was treated with calcium carbonate to adjust pH at different levels. Treated soil was packed into galvanized iron boxes and seeded with grasses to simulate vegetative filter strips. Runoff experiments were conducted with manure solution and inflow, outflow, and leachate samples were collected. Samples were analyzed for sediment and nutrients. It was observed that the soluble nutrients transport was influenced by the pH, and higher ortho-P transport reduction was observed in higher pH. Leaching of NO3-N at higher pH was observed, indicating potential of groundwater pollution from the soil with higher pH. Using calcium carbonate to increase soil pH and thereby reducing transport of soluble nutrient could increase VFS performance. To aid VFS design and evaluation, a model was developed to predict trapping efficiency of sediment, sediment bound P, and dissolved P from VFS. Two procedures were coded into FORTRAN and added into existing VFSMOD model. The model was calibrated and validated using field data. Due to limited data points and difficulties in measuring runoff volume, the model appeared to be under or over predicting. In future, model predictability can be improved by accurately measuring runoff volume and carefully selecting input parameters.North Dakota Department of Health (EPA Section 319 grants

Nutrient and organic matter dynamics in a macrotidal estuary impacted by human activities, the Nanliu Estuary, southern China

Anthropogenic nutrients, mainly from agriculture but also from aquaculture, cause eutrophication. Negative effects include ecosystem degradation via oxygen depletion following organic matter decomposition. Mangrove forests are potential nutrient filters. This study investigates land-derived material inputs into coastal waters of southern China and assesses the effect of mangroves. Nanliu River and Lianzhou Bay comprise multiple human impacts. Transformations and fates of nutrients and organic matter were investigated by biogeochemical field and laboratory methods. The role of mangroves was assessed by field measurements, incubation experiments, and model calculations. Results show that land-use in river catchments dominantly contributes to eutrophication in coastal waters. This is a regional rather than local conservation issue. Natural factors do not sufficiently reduce nutrients, making improved nutrient management the only option preventing eutrophication