A spatial-temporal optimization approach to watershed management: Acid mine drainage treatment in the Cheat River watershed, WV, USA

Most water management studies concentrate on the inter-temporal allocation problem or, more recently, spatial dynamics - but not both. While early spatial-temporal studies focused on the allocation of water quantity, this paper presents an approach to water quality analysis that incorporates both spatial and temporal dynamics in a watershed framework. The acid mine drainage (AMD) problem in the Cheat River watershed of West Virginia, USA, serves as a case study and provides an opportunity to test the modeling approach developed. The empirical models are written in General Algebraic Modeling System (GAMS) and solved using the CPLEX mixed integer programming package. The results suggest that available investments should be concentrated in heavily impaired stream segments. The model can be used to assess the economic implications of alternative watershed Total Maximum Daily Load (TMDL) implementation or other management strategies.     

Risk of Myxobolus cerebralis infection to rainbow trout in the Madison River, Montana, USA.

Myxobolus cerebralis, the parasite that causes salmonid whirling disease, has had detrimental effects on several salmonid populations in the Intermountain West, including the rainbow trout in the Madison River, Montana, USA. The goal of this study was to examine relationships among characteristics of the environment, Tubifex tubifex (the alternate host) populations, and rainbow trout whirling disease risk in the Madison River. Environmental characteristics were measured in side channels of the Madison River, and differences were described with a principal components analysis. The density of T. tubifex, the prevalence of infection in T. tubifex, and the density of infected T. tubifex were determined for the side channels using benthic core samples and examination of live tubificids for infection. The site-specific contribution to whirling disease risk in the side channels was determined using in situ exposures of sentinel rainbow trout. Regression analyses were used to determine correlations among these characteristics. Side channels differed in site-specific contribution to rainbow trout whirling disease risk, which was positively correlated to the density of infected T. tubifex. Side channels with fine sediments and lower water temperatures made greater site-specific contribution to whirling disease risk and had higher densities of infected T. tubifex than side channels with coarser sediments and higher temperatures. The ability to characterize areas of high whirling disease risk is essential for improving our understanding of the dynamics of M. cerebralis such that appropriate management strategies can be implemented. In addition, this study provides a model of how the disease ecology of complex aquatic parasites can be examined when the influential processes operate on different spatial scales.     

Feedbacks between bivalve density, flow, and suspended sediment concentration on patch stable states

We explore the role of biophysical feedbacks occurring at the patch scale (spatial scale of tens of meters) that influence bivalve physiological condition and affect patch stability by developing a numerical model for the pinnid bivalve, Atrina zelandica, in cohesive sediments. Simulated feedbacks involve bivalve density, flow conditions (assumed to be primarily influenced by local water depth and peak current speed), suspended sediment concentration (evaluated through a balance between background concentration, deposition, and erosion), and changes in the physiology of Atrina derived from empirical study. The model demonstrates that high bivalve density can lead to skimming flow and to a concomitant decrease in resuspension that will affect suspended sediment concentration over the patch directly feeding back on bivalve physiology. Consequently, for a given flow and background suspended sediment load, the stability of a patch directly depends on the size and density of bivalves in the patch. Although under a range of conditions patch stability is ensured independently of bivalve density, simulations clearly indicate that sudden changes in bivalve density or suspended sediment concentration can substantially affect patch structure and lead to different stable states. The model highlights the role of interactions between organisms, flow, and broader scale environmental conditions in providing a mechanistic explanation for the patchy occurrence of benthic suspension feeders.     

Applications of Venturi Principle to Water Aeration Systems

The concentration of dissolved oxygen is an important indicator of water quality because aquatic life lives on the dissolved oxygen in the water. Aeration can increase dissolved oxygen when levels become deficient. Hydraulic structures can significantly improve dissolved oxygen levels by creating turbulent conditions where small air bubbles are carried into the bulk of the flow. Recent researches have focused on developing measurement and predictive techniques for oxygen transfer at hydraulic structures to maintain and enhance water quality. However, reviewing existing studies on aeration performance of hydraulic structures, it seems that there are not too many studies on venturi aeration. The present paper shows applications of venturi principle to water aeration systems. The aeration characteristics of venturi nozzle, venturi conduit and venturi weir are analyzed. The results indicate that venturi aeration might contribute significantly to air entrainment and aeration efficiency. Therefore, venturi device can be used as highly effective aerator in aeration processes.     

Cultivation of Chlorella sp. HQ in inland saline-alkaline water under different light qualities

• Optimal growth of Chlorella in inland saline-alkaline water was achieved by blue LED. • Lipids of Chlorella sp. HQ were mainly composed of C16:0 and C18:2 under various LEDs. • The BiodieselAnalyzer^© software was used to evaluate the Chlorella biodiesel quality. • Chlorella sp. HQ was a high-quality feedstock for biodiesel production. Inland saline-alkaline water can be used for the low-cost cultivation of microalgae, but whether algal biomass under various light sources has the potential to produce biodiesel remains to be developed. Herein, the influence of different light-emitting diode (LEDs) light colors (blue, red, white, mixed blue-red, and mixed blue-white LED) on the growth performance, lipid accumulation, and fatty acid composition of Chlorella sp. HQ cultivated in inland saline-alkaline water was investigated. The highest algal density was obtained under blue LEDs at the end of cultivation, reaching 1.93±0.03 × 10⁷ cells/mL. White LEDs can improve biomass yield, total lipid yield, and triacylglycerol yield per algal cell. The main fatty acid components of Chlorella from inland saline-alkaline water were palmitic acid and linoleic acid. The BiodieselAnalyzer^© software was used to predict algal biodiesel quality by estimating different quality parameters. The cetane number, kinematic viscosity, and density of Chlorella biodiesel were 51.714–67.69, 3.583–3.845 mm²/s, and 0.834–0.863 g/cm³, respectively. This further proved that the Chlorella biomass obtained from inland saline-alkaline water has the potential to be used as a high-quality biodiesel feedstock.     

Field-scale roles of density, temperature, nitrogen, and predation on aphid population dynamics

Robust analyses of noisy, stage-structured, irregularly spaced, field-scale data incorporating multiple sources of variability and nonlinear dynamics remain very limited, hindering understanding of how small-scale studies relate to large-scale population dynamics. We used a novel, complementary Bayesian and frequentist state-space model analysis to ask how density, temperature, plant nitrogen, and predators affect cotton aphid (Aphis gossypii) population dynamics in weekly data from 18 field-years and whether estimated effects are consistent with small-scale studies. We found clear roles of density and temperature but not of plant nitrogen or predators, for which Bayesian and frequentist evidence differed. However, overall predictability of field-scale dynamics remained low. This study demonstrates stage-structured state-space model analysis incorporating bottom-up, top-down, and density-dependent effects for within-season (nearly continuous time), nonlinear population dynamics. The analysis combines Bayesian posterior evidence with maximum-likelihood estimation and frequentist hypothesis testing using average one-step-ahead residuals.     

Historical metal concentrations in lacustrine food webs revealed using fossil ephippia from Daphnia.

Metal contamination of freshwater ecosystems is increasingly prevalent due to anthropogenic activities such as metal smelting and fossil fuel combustion. While toxicological studies focus on aqueous metal concentrations that result in lethal or sublethal responses, currently the only method for reconstructing a lake's metal contamination history is through an examination of the sedimentary deposits. In this paper, we suggest that cladoceran diapausing eggs (ephippia), which are abundant in nature and accumulate maternally derived metals, can be used to measure historical variations in biologically relevant metals that derive from the water column (water, diet). Linear regressions of total metal content against ephippia density or mass were strong (R2 > 0.80, P < 0.04) and revealed that metals were incorporated into ephippia with little contamination from the sediment matrix. Comparison of metal concentrations in ephippia and bulk sediments from three lakes demonstrated that some metals associated with urban sources (Cd, Cr, Mo) were preferentially concentrated in ephippia, whereas concentrations of other metals indicating landscape erosion (Al, Ca, Fe, Mn) exhibited greater concentrations in bulk sediments than in diapausing eggs. Because historical changes in metals within fossils and bulk sediments were uncorrelated in most instances, past variation in the metal content of ephippia provided a unique history of food web exposure to metals in the water column.     

Simultaneous removal of Co,Cu, and Cr from water by electrocoagulation

This study provides an electrocoagulation process for the removal of metals such as cobalt, copper, and chromium from water using magnesium as anode and galvanized iron as cathode. The various parameters like pH, current density, temperature, and inter electrode distance on the removal efficiency of metals were studied. The results showed that maximum removal efficiency was achieved for cobalt, copper, and chromium with magnesium as anode and galvanized iron as cathode at a current density of 0.025?A?dm^?2 at pH 7.0. First- and second-order rate equations were applied to study adsorption kinetics. The adsorption process follows second-order kinetics model with good correlation. The Langmuir and Freundlich adsorption isotherm models were studied using the experimental data. The Langmuir adsorption isotherm favors monolayer coverage of adsorbed molecules for the adsorption of cobalt, copper, and chromium. Temperature studies showed that adsorption was endothermic and spontaneous in nature.     

Determining the viability of marine protists using a combination of vital, fluorescent stains

Determining the viability of protists and small microzooplankton has long been a focus of studies in marine biology and ecology. It is especially relevant in the issue of shipborne invasive species, and impending international guidelines and various national regulations on the allowable concentrations of organisms in discharged ballast water have spurred the growth of an industry that develops and manufactures ballast water management systems. The success of management systems and ability of ships to meet ballast water discharge standards is determined by the number of viable organisms in treated water. Here, we propose combining two vital, fluorescent stains (fluorescein diacetate [FDA] and 5-chloromethylfluorescein diacetate [CMFDA]) with direct microscopic observation to enumerate viable organisms ≥10 and <50 μm in minimum dimension (nominally protists). This approach was validated in four locations in the United States to determine the efficacy of the stains. Although the accuracy of the stains varied by geographic location and the taxonomic composition of the planktonic assemblage, combining fluorescent stains is a robust, powerful tool that can be optimized for the species present at each location. While this method was developed for analyzing viable organisms in treated ballast water, it may also be used or adapted for any field of research that examines a broad taxonomic range of autotrophic and heterotrophic plankton.     

Controls on vegetation structure in Southwestern ponderosa pine forests, 1941 and 2004

Long-term studies can broaden our ecological understanding and are particularly important when examining contingent effects that involve changes to dominance by long-lived species. Such a change occurred during the last century in Southwestern (USA) ponderosa pine (Pinus ponderosa) forests. We used five livestock grazing exclosures established in 1912 to quantify vegetation structure in 1941 and 2004. Our objectives were to (1) assess the effects of historical livestock grazing on overstory structure and age distribution, (2) assess the effects of recent livestock grazing and overstory on understory vegetation, and (3) quantify and explain changes in understory vegetation between 1941 and 2004. In 1941, canopy cover of tree regeneration was significantly higher inside exclosures. In 2004, total tree canopy cover was twice as high, density was three times higher, trees were smaller, and total basal area was 40% higher inside exclosures. Understory species density, herbaceous plant density, and herbaceous cover were negatively correlated with overstory vegetation in both years. Most understory variables did not differ between grazing treatments in 1941 but were lower inside exclosures in 2004. Differences between grazing treatments disappeared once overstory effects were accounted for, indicating that they were due to the differential overstory response to historical livestock grazing practices. Between 1941 and 2004, species density declined by 34%, herbaceous plant density by 37%, shrub cover by 69%, total herbaceous cover by 59%, graminoid cover by 39%, and forb cover by 82%. However, these variables did not differ between grazing treatments or years once overstory effects were accounted for, indicating that the declines were driven by the increased dominance of the overstory during this period. Our results demonstrate that historical livestock grazing practices are an aspect of land-use history that can affect ecosystem development. Grazing history must be considered when extrapolating results from one site to another. In addition, the understory vegetation was more strongly controlled by the ponderosa pine overstory than by recent livestock grazing or by temporal dynamics, indicating that overstory effects must be accounted for when examining understory responses in this ecosystem.     

Geographical associations between aluminium in drinking water and death rates with dementia (including Alzheimer's disease), Parkinson's disease and amyotrophic lateral sclerosis in Norway

Comparisons of maps and correlation and regression analysis indicate a geographical association between aluminium (Al) in drinking water and registered death rates with dementia (coded from death certificates as the underlying or a contributory cause of death) in Norway. High levels of Al in drinking water are in most cases related to acid precipitation. In general, correlations between aggregate environmental measurements and mortality are a weak source of evidence for risk factors for disease, however, and interpretations regarding cause-and-effect relationships should therefore be made with great care. The major uncertainty probably relates to the use of registered death rates with dementia as a measure of incidence rates of Alzheimer's disease. The dementia rates are correlated with population density, and it is possible that the association between AI and dementia might be due to differences in diagnosis and reporting of dementia. Thus, the present study can only be regarded as introductory, and further epidemiological studies are needed to help elucidate the role of AI in Alzheimer's disease. The results provide little evidence of an association between AI in drinking water and Parkinson's disease or amyotrophic lateral sclerosis.     

Faunal relationships among the near-reef zooplankton at three locations on heron reef,great barrier reef,and seasonal changes in this fauna

Samples of zooplankton were collected using a light trap at 5 sites in 3 locations on Heron Reef: (a) near the surface of open water 300 m south of the reef crest; (b) near the surface and at the substratum on the upper reef slope; (c) near the surface and at the substratum on a patch reef in the Heron lagoon. The collections made were analysed with respect to: (a) distribution and abundance of the taxa present; (b) faunistic relationships among samples from the 5 sites; (c) seasonal changes in both of these factors. A total of 181 taxa were recognised, many of which are identified to species, and many of which are demersal or epi-benthic in habits. At all sites, the abundance of animals increases from May to November, and faunal similarity between sites also changes. In May, reef collections are generally similar to one another and, with the exception of the slope surface collection, distinct from the open water collection. In September this pattern is enhanced, but in November slope collections more closely resemble the open water collection, while the lagoon collections are quite distinct from slope and open water collections. Lagoon surface and substratum collections also differ considerably from each other at this time. A MULTCLAS cluster analysis of the samples confirms the pattern of change in faunal relationships seen from examination of the collections. Dark-trap samples were used to assess the bias introduced by using a light to attract the animals, as well as to estimate the density of the fauna sampled. Lighttrap samples over-represent calanoid and harpacticoid copepods and gammarid amphipods, but the bias is minor and does not prevent use of a light trap as an efficient sampling tool for near-reef plankton. The density of the fauna is approximately 700 animals m^-3 at all sites. This may be a lower density than in more tropical regions. Pronounced seasonal changes occur in faunal composition of collections from open water and from surface sites. The substratum collections show more constant faunas throughout the year. Major changes are primarily in the proportions of copepods and cumaceans present. Changes in amphipod numbers are also important at lagoon sites.     

Life cycle assessment of low impact development technologies combined with conventional centralized water systems for the City of Atlanta,Georgia

Low-impact development (LID) technologies, such as bioretention areas, rooftop rainwater harvesting, and xeriscaping can control stormwater runoff, supply non-potable water, and landscape open space. This study examines a hybrid system (HS) that combines LID technologies with a centralized water system to lessen the burden on a conventional system (CS). CS is defined as the stormwater collection and water supply infrastructure, and the conventional landscaping choices in the City of Atlanta. The study scope is limited to five single-family residential zones (SFZs), classified R-1 through R-5, and four multi-family residential zones (MFZs), classified RG-2 through RG-5. Population density increases from 0.4 (R-1) to 62.2 (RG-5) persons per 1,000 m2. We performed a life cycle assessment (LCA) comparison of CS and HS using TRACI 2.1 to simulate impacts on the ecosystem, human health, and natural resources.We quantified the impact of freshwater consumption using the freshwater ecosystem impact (FEI) indicator. Test results indicate that HS has a higher LCA single score than CS in zones with a low population density; however, the difference becomes negligible as population density increases. Incorporating LID in SFZs and MFZs can reduce potable water use by an average of 50% and 25%, respectively; however, water savings are negligible in zones with high population density (i.e., RG-5) due to the diminished surface area per capita available for LID technologies. The results demonstrate that LID technologies effectively reduce outdoor water demand and therefore would be a good choice to decrease the water consumption impact in the City of Atlanta.

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Production dynamics of the eelgrass, <Emphasis Type="Italic">Zostera marina</Emphasis> in two bay systems on the south coast of the Korean peninsula

Production dynamics of eelgrass, Zostera marina was examined in two bay systems (Koje Bay and Kosung Bay) on the south coast of the Korean peninsula, where few seagrass studies have been conducted. Dramatically reduced eelgrass biomass and growth have been observed during summer period on the coast of Korea, and we hypothesized that the summer growth reduction is due to increased water temperature and/or reduced light and nutrient availabilities. Shoot density, biomass, morphological characteristics, leaf productivities, and tissue nutrient content of eelgrass were measured monthly from June 2001 to April 2003. Water column and sediment nutrient concentrations were also measured monthly, and water temperature and underwater irradiance were monitored continuously at seagrass canopy level. Eelgrass shoot density, biomass, and leaf productivities exhibited clear seasonal variations, which were strongly correlated with water temperature. Optimal water temperature for eelgrass growth in the present study sites was about 15–20°C during spring period, and eelgrass growths were inhibited at the water temperature above 20°C during summer. Daily maximum underwater photon flux density in the study sites was usually much higher than the light saturation point of Z. marina previously reported. Densities of each terminal, lateral, and reproductive shoot showed their unique seasonal peak. Seasonal trends of shoot densities suggest that new eelgrass shoots were created through formation of lateral shoots during spring and a part of the vegetative shoots was transformed into flowering shoots from March. Senescent reproductive shoots were detached around June, and contributed to reductions of shoot density and biomass during summer period. Ambient nutrient level appeared to provide an adequate reserve of nutrient for eelgrass growth throughout the experimental period. The relationships between eelgrass growth and water temperature suggested that rapid reductions of eelgrass biomass and growth during summer period on the south coast of the Korean peninsula were caused by high temperature inhibition effects on eelgrass growth during this season.     

罗非鱼-附着藻-沉水植物相互关系研究进展

在浅水富营养化湖泊中,沉水植被是决定湖泊清水态或混水态的关键因子。而附着藻对沉水植物强烈的遮阴作用以及对碳源、营养盐等资源强烈的竞争,成为限制沉水植物群落生长和发展的关键因子。罗非鱼作为一种杂食性鱼类,具有牧食附着藻的能力,其下行效应（top-down effect）可以在一定程度上减轻附着藻对沉水植物生长的这种不利影响。因此,作为我国南方水体中的优势种类,适当种群密度的罗非鱼在富营养化浅水湖泊生态修复过程中是可加以利用,并在一定程度上抑制了附着藻的生长和发展,有利于浅水湖泊的生态修复和管理。同时,罗非鱼也具有通过摄食、排泄等活动加速水体氮、磷营养盐再生,牧食浮游动物、沉水植物等不利的一面。因此,在综合考虑多种因素条件下,需要对罗非鱼-附着藻-沉水植物三者之间的相互关系进行深入研究,探讨生态系统对罗非鱼的响应,这对我国南方浅水富营养化湖泊的生态恢复与管理,尤其是沉水植被的重建与保护具有重要的理论意义和实践价值。     

A box model of carrying capacity for suspended mussel aquaculture in Lagune de la Grande-Entrée,Iles-de-la-Madeleine,Québec

An object-oriented model of environment–mussel aquaculture interactions and mussel carrying-capacity within Lagune de la Grande-Entrée (GEL), Iles-de-la-Madeleine, Québec, was constructed to assist in development of sustainable mussel culture in this region. A multiple box ecosystem model for GEL tied to the output of a hydrodynamic model was constructed using Simile software, which has inherent ability to represent spatial elements and specify water exchange between modelled regions. Mussel growth and other field data were used for model validation. Plackett–Burman sensitivity analysis demonstrated that a variety of bioenergetic parameters of zooplankton and phytoplankton submodels were important in model outcomes. Model results demonstrated that mussel aquaculture can be further developed throughout the lagoon. At present culture densities, phytoplankton depletion is minimal, and there is little food limitation of mussel growth. Results indicated that increased stocking density of mussels in the existing farm will lead to decreased mass per individual mussel. Depending on the location of new farm emplacement within the lagoon, implementation of new aquaculture sites either reduced mussel growth in the existing farm due to depletion of phytoplankton, or exhibited minimum negative impact on the existing farm. With development throughout GEL, an excess of phytoplankton was observed during the year in all modelled regions, even at stocking densities as high as 20 mussels m⁻³. Although mussels cultured at this density do not substantially impact the ecosystem, their growth is controlled by the flux of phytoplankton food and abundance of zooplankton competitors. This model provides an effective tool to examine expansion of shellfish farming to new areas, balancing culture location and density.     

Hydrogeochemical study of the drinking water from the Khaybar village,SW Saudi Arabia

This paper presents the results of chemical analysis of four drinking waters from the Khaybar village, SW Saudi Arabia. Four main water‐wells in the Khaybar village were investigated. The Khaybar ground water is clear without odour but its taste differs according to the amount of total dissolved solids (T.D.S.). The pH values of such water are slightly alkaline. T.D.S. of the Khaybar water is higher than the Saudi highest desired level, but it is generally within the Saudi maximum permissible level.

Good drinking quality water can be found in Al Mazaab and Al Tilah water‐wells in the Khaybar village. The other two water‐wells can be used for irrigation purposes only.

The geological features of the Khaybar area suggest a meteoric origin for the Khaybar ground water which has been stored in the fractured metamorphic and igneous rocks and in alluvial deposits.     

物种敏感度分布的非参数核密度估计模型

针对目前物种敏感度分布参数方法建模所存在的缺点,首次提出基于非参数核密度估计方法的物种敏感度分布模型,并提出相应的最优窗宽和检验方法。选用无机汞作为案例研究对象,利用非参数核密度估计方法和3种传统参数模型分别推导了保护我国水生生物的无机汞的急性水质基准值。结果表明,非参数核密度估计方法在推导无机汞水质基准中的稳健性和精确度都大大优于传统参数模型,能够更好地构建物种敏感度分布曲线。该方法的提出丰富了水质基准的理论方法学,为更好地保护水生生物提供了有力的支撑。     

Validation of an enzyme linked immunosorbent assay (elisa) for cyprinus carpio l. vitellogenin,as a biomarker of reproductive disorders

Vitellogenin is a female sex-specific protein, and a validated and suitable method for its assay can be applied as a biomarker of reproductive disorders in male and female aquatic animals. Therefore, the present study was designed to validate an ELISA for measuring plasma vitellogenin in wild carp ( Cyprinus carpio L.) living in the Lake of Trasimeno (Umbria, Italy); plasma samples were taken during pre-spawning, spawning, and post-spawning periods; in addition to vitellogenin, in both male and female carps, plasma changes of estradiol-17 g were monitored together with those of estrogen receptor density in the liver. In females, VTG showed high seasonality, reaching the highest levels in March during the pre-spawning period; the VTG levels correlated with those of estradiol-17 g ( E 2 ), and with the changes of gonadosomatic index (GSI), while a non parallel trend was found in the liver estrogen receptor (ER) density. In forty percent of males, VTG was found to be present in the plasma and changes of ER density in the liver were observed. The data here reported suggest that the common carp can be a useful sentinel species for biomonitoring studies of environmental estrogens, and of their effects on its reproductive biology.     

Relative size of Aristotle's lantern in Echinometra mathaei occuring at different densities

Like species of sea urchins in Zanzibar and Oregon (USA), Echinometra mathaei (de Blainville) at Rottnest Island, Western Australia, displays variation in the size of Aristotle's lantern relative to the maximum diameter of the test. This variation was associated with local variations in density of urchins at each of two sites in each of two years (1980 and 1981); this association with density was consistent with the proposal that relatively larger lanterns are a response to decreased food availability. Furthermore, variation of relative lantern size associated with local density was similar in magnitude to the variation displayed between sites and between years. This temporal variation demonstrated the plasticity of the relative lantern size over periods as short as 12 mo. Further experimental studies are required before relative length of lanterns can be used as estimates of food availability.