Open Waterways Research Articles

Predicting Advanced Air Mobility Adoption Globally by Machine Learning

Advanced air mobility (AAM) is a sustainable aviation initiative to deliver cargo and passengers in urban and regional locations by electrified drones. The widespread expectation is that AAM adoption worldwide will help to reduce pollution, reduce transport costs, increase accessibility, and enable a more reliable and resilient supply chain. However, most countries lack regulations that legalize AAM. A fragmented regulatory approach hampers the progress of business prospectors and international organizations concerned with human welfare. Therefore, amidst high uncertainty, knowledge of indicators that can predict the propensity for AAM adoption will help nations and organizations plan for drone use. This research finds predictive indicators by assembling a unique dataset of 36 economic, social, environmental, governance, land use, technology, and transportation indicators for 204 nations. Subsequently, the best of 12 different machine learning models ranks the predictive importance of the indicators. The gross domestic product (GDP) and the regulatory quality index (RQI) developed by the Worldwide Governance Indicators (WGI) project were the two top predictors. Just as importantly, the poor predictors were as follows: the social progress index developed by the Social Progress Imperative, the WGI rule-of-law index, land use characteristics such as rural and urban proportions, borders on open waterways, population density, technology accessibility such as electricity and cell phones, carbon dioxide emission level, aviation traffic, port traffic, tourist arrivals, and roadway fatalities.

Numerical Investigation of the Hydraulic Impacts Induced by a Bioreactor Installed in a Contaminated Waterway

Because of climate change, the erection of dams through transboundary rivers, and the shortage of water resources, countries worldwide are facing several challenges. Unconventional water resources such as recycling wastewater are urgently needed to overcome the demand–supply gap. The bioreactor is considered an effective means of removing contaminants and enhancing the self-purification on open waterways. This study numerically investigates the hydraulic impacts of an installed bioreactor in an open channel. Three-dimensional numerical models were developed based on computational fluid dynamics (CFD) to simulate different arrangements of the gravel bioreactor installed in the open channel. The relative heading up increased as Froude’s number increased, regardless of the number of bio-filter segments. The heading up values decreased significantly when dividing the bio-filter into several segments with the same total length. The relative heading up decreased linearly as the distance between the bio-filter segments increased for a constant bio-filter length. On the other hand, the relative heading up increased linearly as the length of the bio-filter segments increased for a constant inter-distance of the bio-filter segments. For simultaneous changes in both the length of the bio-filter segments and their inter-distance, the relative heading up increased nonlinearly with the product of both the length and inter-distance. This study confirmed that the greater the inclination angles of the bio-filter’s face, the greater the heading up. When considering the base case with the inclination angle of 45°, the increasing ratios of the relative heading up were 14.5%, 16.1%, and 19.7%, corresponding to the angles 60°, 75°, and 90°, respectively.

Estimating abundance of an elusive cetacean in a complex environment: Harbor porpoises (Phocoena phocoena) in inland waters of Southeast Alaska

The harbor porpoise (Phocoena phocoena) is common in temperate waters of the eastern North Pacific Ocean, including Southeast Alaska inland waters, a complex environment comprised of open waterways, narrow channels, and inlets. Two demographically independent populations are currently recognized in this region. Bycatch of porpoises in the salmon drift gillnet fisheries is suspected to occur regularly. In this study, we apply distance sampling to estimate abundance of harbor porpoise during ship surveys carried out in the summer of 2019. A stratified survey design was implemented to sample different harbor porpoise habitats. Survey tracklines were allocated following a randomized survey design with uniform coverage probability. Density and abundance for the northern and southern Southeast Alaska inland water populations were computed using a combination of design-based line- and strip-transect methods. A total of 2,893 km was surveyed in sea state conditions ranging from Beaufort 0 to 3 and 194 harbor porpoise groups (301 individuals) were detected. An independent sighting dataset from surveys conducted between 1991 and 2012 were used to calculate the probability of missing porpoise groups on the survey trackline (g[0]=0.53, CV=0.11). Abundance of the northern and southern populations were estimated at 1,619 (CV=0.26) and 890 (CV=0.37) porpoises, respectively. Bycatch estimates, which were only obtained for a portion of the drift gillnet fishery, suggest that mortality within the range of the southern population may be unsustainable. Harbor porpoises are highly vulnerable to mortality in gillnets, therefore monitoring abundance and bycatch is important for evaluating the potential impact of fisheries on this species in Southeast Alaska.

Identification, classification and quantification of microplastics in road dust and stormwater

Microplastics (MP) have become a major emerging class of pollutants representing significant eco-toxicological risks for ecosystems and marine environments. The aim of this study was to identify, classify and quantify MP present in both road dust and stormwater samples. A significantly higher level of MPs within road dust samples was detected from industrial area (1130 particles/kg of dust) than from residential area (520 particles/kg of dust), while stormwater samples from industrial and residential sites yielded 26 particles/L and 17 particles/L, respectively. Fiber-like shape accounted for 53% and 74% in road dust and stormwater samples, respectively. The main polymeric materials collected for both road dust and stormwater samples were, in order of occurrence (i) low-density polyethylene, (ii) high-density polyethylene, (iii) polypropylene, (iv) polyethylene terephthalate, (v) polystyrene, (vi) polyester and (vii) poly (amide). Most of the MP had an average maximum dimension smaller than 2 mm for both road dust and stormwater samples. The results from this study demonstrates that road dust is a significant contributor to MP pollution through direct polymeric materials wear off and transfer through stormwater, which eventually will end up in open water ways and broader ecological niches.

Assess the performance of chemical coagulation process for microplastics removal from stormwater

Microplastic (MP) is considered as one of the emerging pollutants in marine environments. Because of low density and small particle size (<5 mm), MPs are easily discharged into open waterways by stormwater runoff. Therefore, the aim of this study was to investigate the effect of coagulation process for the removal of different types of MPs such as low-density polyethylene (LDPE), high-density polyethylene (HDPE) and polypropylene (PP) from synthetic stormwater. The effect of different types of a coagulant such as alum and polyacrylamide (PAM), dosages of coagulants, solution pH and weathering conditions was investigated for the removal of MPs. Results found that a combination of alum and PAM performed better than standalone coagulant for MPs removal. The removal of all three types of MPs was high at low pH (3–5). It is also found that the removal efficiency of LDPE, HDPE and PP was 92 %, 84 % and 96 %, respectively under the weathering conditions. The mechanisms for MP removal were charge neutralization and hydrophobic interaction between MP and coagulant flocs. Overall, this study has confirmed that the coagulation process was very effective for removing MP particles under weathering conditions.

Understanding the fate of nano-plastics in wastewater treatment plants and their removal using membrane processes

Nanoplastics (NPs) have become a major environmental issue due to their adverse effect on the water environment. Wastewater treatment plant (WWTP) is considered as one of the main sources for breaking down of larger-sized plastic debris and microplastics (MPs) into NPs. This study aims to provide a comprehensive understanding of NPs generation in the WWTPs, their physiochemical characteristics and interaction with the WWTPs. It is found that cracking is the major mechanism of plastics fragmentation in the WWTPs. This review also discusses the current membrane process used for NPs removal. It is found that conventional membrane processes are ineffective as they are not designed for NPs removal and fouling is a major obstacle for its application. Therefore, this study concludes by providing an outlook of developing a bio-nanofiltration process that can be used as a tertiary treatment for removing NPs and other components present in water. Such a process can produce NPs-free water for non-potable use or safe discharge into open waterways.

The Lifeguard Rescue Reporting System: Survey Results from a Collaborative Data Collection Method

Several water safety organizations have attempted to improve reporting regarding lifeguard actions in order to better understand the characteristics of successful, non-fatal rescues. In 2003, a collective effort initiated the Lifeguard Rescue Reporting System, an online survey distributed to lifeguards and facility managers across the United States and Canada to better understand rescue actions performed in pools/spas, water parks, and open water areas. After seven years of data collection, the online survey accumulated data reflecting 1,676 rescue actions, collecting information including location, victim characteristics and outcome, rescuer characteristics and strategies, and other general circumstances. Descriptive results indicated that at least half of victims were 14 years old or younger across all settings. Depths of 0.9-1.5m (3-5 ft) represented the range at which incidents most frequently occurred in pools and spas and waterparks, whereas the depth of incidents was generally deeper in natural and open waterways. During rescue incidents, water safety personnel generally identified victims either visually (83-92% of the time) and/or audibly (18-29%), although victim “profiling” was also employed 10-14% of the time to identify at-risk swimmers. Notably, across all three water setting types, no medical aid was required in most cases (60-72%), suggesting the efficacy and essentiality of lifeguards as aquatic first responders. Accordingly, as water-based recreation maintains its popularity, systematically collecting and analyzing data specific to everyday, rescue actions are critical to improving lifeguard education and strategic, data-based operating procedures.

Comparison of the chemistry and mineralogy of ilmenite concentrates sourced from fluvial (Brahmaputra River) and beach placer (Cox’s Bazar) deposits, Bangladesh

Bangladesh has known concentrations of heavy mineral (HM) sand resources in shoreline placer deposits along the southern and eastern coastlines and also within river sand bar placer deposits associated with the extensive river systems throughout the country. The high-grade Cox’s Bazar beach placer deposits are in populated and environmentally sensitive areas making the future of mineral sands exploitation uncertain. In comparison, the Brahmaputra fluvial deposits are less rich in total HMs but constitute a potential major resource.The recovery of Ti-rich ilmenite from beach placer deposits is widespread but rare from fluvial deposits however many river systems in Bangladesh are annually dredged to maintain open waterways offering a new source of heavy minerals. Exploitation will depend on the quality of the ilmenite compared to existing commercially traded material. In this study, ilmenite concentrates derived from fluvial deposits (Brahmaputra River) and beach placer deposits (Cox’s Bazar) were compared using XRF, XRD and EPMA techniques.The level of impurities associated with the Brahmaputra River ilmenite was higher than in the equivalent Cox’s Bazar fractions suggesting possible issues with liberation or the properties of the associated gangue minerals reacted differently to the separation conditions, or both. Ilmenite from both regions exhibited texturally alike grain types and chemically similar compositions with detrital ilmenite from Cox’s Bazar characterised by TiO2 contents ranging from 49–53 wt-% (average 51 wt-%) while the range for the Brahmaputra River was 44–53 wt-% (average 49 wt-%). The slightly higher and much narrower range in TiO2 for the Cox’s Bazar material was consistent with this material having been subject to more chemical weathering resulting from a longer transit time and reworking through wave action. Based on the major and minor element compositions of ilmenites from both sources, the most likely route for processing the ilmenite-rich component would be via the sulphate route to pigment.

Floating wetlands for nutrient removal in eutrophicated coastal lagoons: Decision support for site selection and permit process

Lagoons often suffer from eutrophication. Floating islands planted with native emergent macrophytes offer a solution for internal nutrient removal. These’active barriers’ have been applied in various inland waters, but never in coastal and marine environments. First coastal floating wetlands were installed in different lagoons along the Southern Baltic Sea. However, prior to these installations a comprehensive site selection and permit process had to be carried out. Participatory mapping was performed, law regulations in five European countries investigated and open-source data was integrated to evaluate where suitable installation sites would be. Regional environmental conditions influence how a floating wetland is designed, planted and installed, but do not limit the choice of installation sites explicitly. Restrictions and site choices depend largely on ‘social preferences’ and legal requirements. The participatory mapping showed that visibility of the floating wetlands is important. The proximity to the shore, and hence to potential bathing sites, as well as the proximity to larger cities or tourist destinations are important decision-making factors. The legal steps in the permit process differ in European countries and transferability is difficult. However, all case studies share in common that open waterways and undisturbed maritime traffic are a priority. All investigated lagoons belong to the European Natura 2000 network and are protected habitats. Nevertheless, this does not per se have to complicate the permit process for floating wetlands as the aim of the macrophyte islands is in accordance with the regional, national and European laws on nature protection. A variety of scientific articles proved the usefulness of floating wetlands for nutrient removal in mesocosm experiments. It is time to pave the way for pilot installations in coastal waters. This study with its overview tables on European regulations and graphical visualization serves as a guideline and decision support tool for site selection and permit process.

Reexamination of an outbreak after forty-seven years: Key lessons from the Sagmalcılar outbreak, 1970

In October of 1970, approximately 1,500 people were ill and 52 people died of a cholera outbreak in Sagmalcilar, Istanbul. The outbreak spread over a wide area, carried through the old waterways passing under the garbage-laden areas near the Habipler village and the open waterways in the region of Esenler, Sagmalcilar. The spread of the disease was stopped at the end of October. During this outbreak, all patients were followed up, isolated and treated by the local healthcare workers. A wide range of immunization studies were conducted and water resources and open water zones were chlorinated. The sale of unbottled water, soft drinks and ice in the region was forbidden, and the dead, as well as cemetery grounds were limed. The houses where outbreaks had occurred were marked with yellow papers. In this study, periodical newspapers, related works and official reports of the Grand National Assembly of Turkey were used as resources. In this article, valuable lessons from the Sagmalcilar outbreak were presented and discussed through an analysis of the studies conducted during this epidemic.

A Geospatial Approach to Targeting Constructed Wetlands for Nitrate Removal in Agricultural Watersheds

Constructed wetlands are an effective yet costly strategy for reducing nitrate loading from agricultural subsurface drainage in the Midwestern United States. Targeting wetland placement to sites that intercept high nitrate loads and where topography permits optimal wetland sizing can maximize wetland nitrate removal efficiency while maintaining productive agriculture. The goals of this work were first to determine targeted locations for constructed wetlands to remove nitrate by applying a geospatial approach within an Indiana study region, and second to estimate the nitrate removal efficiency of these proposed wetlands. Criteria were developed from previously published wetland siting criteria associated with the Iowa CREP program and adapted to Indiana-specific conditions. Final criteria included location on cropped land and not within open waterways, size of upland contributing area, presence of tile drainage, and wetland-like topography. Within the study region, 18 locations were found to meet the targeting criteria for strategic wetland placement, requiring land conversion of 0.08% of the study region and intercepting 2.7% of flow from tile-drained lands. Estimated wetland nitrate removal efficiency was on average 37%, including land conversion of wetland and surrounding buffers, resulting in the removal of approximately 1.0% of all nitrate currently exported from tile-drained land in the study area. Wetland placement was most influenced by criteria relating to contributing area, exclusion of streams where wetlands could be potentially located, and topography. Adjusting criteria could allow for a larger set of constructed wetlands and achieve greater overall nitrate reductions at the watershed scale, but this set would likely include less efficient wetlands.

A Measure of Resistance: Detecting Tamiflu Metabolite in Sewage Discharge and River Water

During the flu season each year, combating the different strains of the influenza virus becomes a public health priority, with treatment dependent upon two groups of antiviral drugs: neuraminidase inhibitors and M2 ion channel inhibitors. Oseltamivir phosphate, marketed as Tamiflu, is a popular neuraminidase inhibitor widely used to treat flu symptoms. Oseltamivir carboxylate (OC), Tamiflu’s active metabolite, is known to withstand activated sludge treatment at sewage treatment plants (STPs), but less is known about how much OC may make its way into waterways that receive STP effluent. Now a new study conducted in Kyoto City, Japan, during the 2008–2009 flu season reports some of the first measurements of OP occurrences in STP discharge and in river water [EHP 118:103–107; Ghosh et al.]. According to the World Health Organization, between 250,000 and 500,000 people die each year from influenza, and each year, millions of people take Tamiflu to battle flu symptoms. After the sewage treatment process, the excreted active metabolite remains in STP effluent and travels to waterways where effluent is discharged. The investigators in the current study collected samples from STP effluent and from river water on three different occasions: at the beginning of the flu season, during the peak period, and 2 weeks after the peak period. Using solid-phase extraction followed by liquid chromatography–tandem mass spectrometry, they measured the highest concentration of OC, 293.3 ng/L, in an STP discharge sample collected during the peak of the flu season. Concentration amounts were higher in effluent from STPs that used traditional activated sludge treatment; in contrast, effluent from plants that used advanced ozonation as tertiary treatment contained significantly lower OC levels (37.9 ng/L). River water samples showed a range of OC levels from 6.6 to 190 ng/L during the peak of the flu season. Previous research indicates OC concentrations ranging from 80 to 230 ng/L will disable 50% of the influenza virus. This level of exposure is most likely to kill virus particles that are particularly susceptible to OC, while selecting for viruses that are resistant to the drug’s effects. The authors note, “During a common flu season, waterfowl can ingest large quantities of OC with virus. . . . Exposing waterfowl infected with influenza A virus to elevated levels of OC in open waterways could trigger the development of Tamiflu-resistant viral strains.” The authors suggest ozonation as tertiary treatment that may reduce OC load in STP effluent. They also recommend conducting further investigations to determine the fate of antiviral drugs at every interval of the STP process.

A Measure of Resistance: Detecting Tamiflu Metabolite in Sewage Discharge and River Water

During the flu season each year, combating the different strains of the influenza virus becomes a public health priority, with treatment dependent upon two groups of antiviral drugs: neuraminidase inhibitors and M2 ion channel inhibitors. Oseltamivir phosphate, marketed as Tamiflu, is a popular neuraminidase inhibitor widely used to treat flu symptoms. Oseltamivir carboxylate (OC), Tamiflu’s active metabolite, is known to withstand activated sludge treatment at sewage treatment plants (STPs), but less is known about how much OC may make its way into waterways that receive STP effluent. Now a new study conducted in Kyoto City, Japan, during the 2008–2009 flu season reports some of the first measurements of OP occurrences in STP discharge and in river water [EHP 118:103–107; Ghosh et al.]. According to the World Health Organization, between 250,000 and 500,000 people die each year from influenza, and each year, millions of people take Tamiflu to battle flu symptoms. After the sewage treatment process, the excreted active metabolite remains in STP effluent and travels to waterways where effluent is discharged. The investigators in the current study collected samples from STP effluent and from river water on three different occasions: at the beginning of the flu season, during the peak period, and 2 weeks after the peak period. Using solid-phase extraction followed by liquid chromatography–tandem mass spectrometry, they measured the highest concentration of OC, 293.3 ng/L, in an STP discharge sample collected during the peak of the flu season. Concentration amounts were higher in effluent from STPs that used traditional activated sludge treatment; in contrast, effluent from plants that used advanced ozonation as tertiary treatment contained significantly lower OC levels (37.9 ng/L). River water samples showed a range of OC levels from 6.6 to 190 ng/L during the peak of the flu season. Previous research indicates OC concentrations ranging from 80 to 230 ng/L will disable 50% of the influenza virus. This level of exposure is most likely to kill virus particles that are particularly susceptible to OC, while selecting for viruses that are resistant to the drug’s effects. The authors note, “During a common flu season, waterfowl can ingest large quantities of OC with virus. . . . Exposing waterfowl infected with influenza A virus to elevated levels of OC in open waterways could trigger the development of Tamiflu-resistant viral strains.” The authors suggest ozonation as tertiary treatment that may reduce OC load in STP effluent. They also recommend conducting further investigations to determine the fate of antiviral drugs at every interval of the STP process.

The PRISM3D paleoenvironmental reconstruction

The Pliocene Research, Interpretation and Synoptic Mapping (PRISM) paleoenvironmental reconstruction is an internally consistent and comprehensive global synthesis of a past interval of relatively warm and stable climate. It is regularly used in model studies that aim to better understand Pliocene climate, to improve model performance in future climate scenarios, and to distinguish model-dependent climate effects. The PRISM reconstruction is constantly evolving in order to incorporate additional geographic sites and environmental parameters, and is continuously refined by independent research findings. The new PRISM three dimensional (3D) reconstruction differs from previous PRISM reconstructions in that it includes a subsurface ocean temperature reconstruction, integrates geochemical sea surface temperature proxies to supplement the faunal-based temperature estimates, and uses numerical models for the first time to augment fossil data. Here we describe the components of PRISM3D and describe new findings specific to the new reconstruction. Highlights of the new PRISM3D reconstruction include removal of Hudson Bay and the Great Lakes and creation of open waterways in locations where the current bedrock elevation is less than 25m above modern sea level, due to the removal of the West Antarctic Ice Sheet and the reduction of the East Antarctic Ice Sheet. The mid-Piacenzian oceans were characterized by a reduced east-west temperature gradient in the equatorial Pacific, but PRISM3D data do not imply permanent El Niño conditions. The reduced equator-to-pole temperature gradient that characterized previous PRISM reconstructions is supported by significant displacement of vegetation belts toward the poles, is extended into the Arctic Ocean, and is confirmed by multiple proxies in PRISM3D. Arctic warmth coupled with increased dryness suggests the formation of warm and salty paleo North Atlantic Deep Water (NADW) and a more vigorous thermohaline circulation system that may have provided the enhanced ocean heat transport necessary to move warm surface water to the Arctic. New deep ocean temperature data also suggests greater warmth and further southward penetration of paleo NADW.

Towards the development of intelligent navigation support systems for group shipping and global marine traffic control

Computerised navigation is a developing technology in a branch of autonomous and intelligent engineering systems. It aims to enhance safety and security at sea and to improve the reliability of ship-to-ship operations and global marine traffic control. A recently standardised automatic identification system (AIS) takes full advantage of GPS-based real-time positioning and timing information of ships. The use of the AIS is steadily growing to meet the needs of the merchant shipping and fishing industries. Nevertheless, a significant decrease in the number of ship accidents and hazardous incidents in open waterways has yet to occur. The work gathered in this paper is to establish a proactive means to prevent marine accidents by the use of the full potential of the AIS. Specifically, this paper describes the development of an AIS synthesis-capable navigation support system enhanced with a degree of intelligence built from a physical model suitable to capture the dynamics of group-based navigation of ocean-going vessels. The system envisioned is to provide adequate decision-making support for group shipping, especially during the critical maneuvering in restricted areas such as channel passing and harbour approaches. Foundations for and experimental results of this study, including an analysis with the simulated traffic of Tokyo Uraga Channel route, are presented.

Integrating Ranch Forage Production, Cattle Performance, and Economics in Ranch Management Systems for Southern Florida

The presence of grazing cattle near open waterways has created environmental concerns related to the potential for water contamination. In Florida the removal of cattle from grazing landscapes or decreasing stocking density is being investigated as one option to improve the quality of surface water runoff draining into Lake Okeechobee, Florida. The objective of this study was to determine the effects of stocking rate on cow-calf performance, forage availability and quality, and ranch economic performance. Experimental pastures were established on a southern Florida cow-calf operation with stocking rates of 0.58, 1.01, and 1.35 ha·cow -1 on summer pastures and 0.93, 1.62, and 2.16 ha·cow -1 on winter pastures, corresponding to high, medium, and low rates, respectively. The study was conducted over 4 consecutive production years. Cow body condition scores (BCS), pregnancy rate, and calf average daily gain were used as measures of animal performance. Forage utilization was estimated by measuring the difference between forage yield inside and outside grazing exclusion cages and forage quality by crude protein and in vitro organic matter digestibility . Forage yield, utilization, and quality were not significantly affected by stocking rate. Although statistically not significant ( P = 0.17), cattle in the high stocking rate experienced a numerically greater loss of BCS following the winter grazing period, but stocking rate did not affect pregnancy rate or calf gains. Production (kg weaned calves·ha -1 ) was increased ( P < 0.01) for a high stocking rate compared with medium and low stocking rates. Overall ranch profitability will decrease as stocking rates decline. Ranch revenues decrease one-for-one as stocking rates decrease. At the same time, unit cow costs increase at an increasing rate as fewer brood cows are left to support the ranch's fixed cost structure. La presencia de ganado apacentando cerca de las vías acuáticas ha creado una preocupación ambiental relacionada con el potencial de contaminación del agua. En Florida, la remoción del ganado de los pastizales o la disminución de la densidad de carga animal están siendo investigadas como una opción para mejorar la calidad del agua del escurrimiento superficial que drena en el lago Okeechobee en Florida. El objetivo de este estudio fue determinar los efectos de la carga animal en el comportamiento productivo del binomio vaca-becerro, la disponibilidad y calidad del forraje y los aspectos económicos del rancho. Las praderas experimentales se establecieron en el sur de Florida en un rancho dedicado al sistema vaca-becerro con cargas animal de 0.58, 1.01, y 1.35 ha·vaca -1 para las praderas de verano y de 0.93, 1.62, y 2.16 ha·vaca -1 para las praderas de invierno, que corresponden a cargas alta, media y baja respectivamente. El estudio se condujo durante cuatro años productivos consecutivos. La clasificación de la condición corporal (BCS), tasa de preñez y las ganancias de peso diarias promedio de los becerros se usaron como medidas del comportamiento animal. La utilización del forraje fue estimada midiendo la diferencia entre el rendimiento de forraje dentro y fuera de jaulas de exclusión y la calidad del forraje determinando la proteína cruda y la digestibilidad in vitro de la materia orgánica. El rendimiento de forraje, la utilización y calidad no fueron afectadas significativamente por la carga animal. Aunque estadísticamente las diferencias no fueron significativas ( P = 0.17), el ganado en la carga alta experimentó una pérdida numéricamente mayor de la condición corporal después periodo de apacentamiento en invierno, pero la carga animal no afectó la tasa de preñez o la ganancia de peso de los becerros. La producción (kg de becerro destetado·ha -1 ) se incrementó ( P < 0.01) en la carga animal alta en comparación con las cargas media y baja. La rentabilidad global del rancho decrecerá conforme la carga animal disminuye. Los ingresos del rancho disminuyen al uno por uno conforme la carga animal disminuye. Al mismo tiempo, los costos unitarios por vaca se incrementan al aumentar la carga y conforme una pocas vacas con cría son dejadas para soportar la estructura fija de costos del rancho.

Field monitoring and evaluation of innovative solutions for cleaning storm water runoff

Urbanization increases the variety and amount of pollutants transported to receiving waters. Sediment from development and new construction; oil, grease, and toxic chemicals from automobiles; nutrients and pesticides from turf management and gardening; viruses and bacteria from failing septic systems; road salts; and heavy metals are examples of pollutants generated in urban areas. Sediments and solids constitute the largest volume of pollutant loads to receiving waters in urban areas. When runoff enters storm drains, it carries many of these pollutants with it. In older cities, this polluted runoff is often released directly into open waterways without any treatment. Increased pollutant loads can harm fish and wildlife populations, kill native vegetation, foul drinking water supplies, and make recreational areas unsafe. The objective of the study, performed by University of Pavia (Italy), University of Brescia (Italy) and GreenTechTexas International (US), reported herein is to evaluate the use of an innovative stormwater technology (EcoDräin) to reduce pollution due to urban runoff in existing urban areas. The paper describes the methodology and the results achieved with tests conducted in laboratory in Pavia University in Italy and in two pilot areas in Italy and in Australia to investigate the EcoDräin's effectiveness for oil and heavy metals retention and sediment trapping. In the tests performed in a marina near Sydney in Australia a reduction has been achieved in oil and grease concentration higher than 95% and a reduction in metal concentration (particularly Copper, Lead and Zinc) close to 98%. The paper also describes the methodology of the analysis on the absorbing material after its use and the consequent determination of the most efficient and environmentally safe way to dispose of consummated absorbent.

Ploidy of Feral Grass Carp in the Chesapeake Bay Watershed

We examined the ploidy of feral grass carp Ctenopharyngodon idella captured from open waterways of the Chesapeake Bay watershed. Using flow cytometry, we determined the ploidy of blood and gonads (when mature ovaries or testes were present) to elaborate upon several issues associated with stocking grass carp, namely, escapism, illegal stockings, and the reproductive potential of triploid grass carp. During a 3-year period (1994–1997), ploidy was determined for 11 of 16 feral individuals, 2 of which were diploid (18%). In the survey, we detected gonadal development in one diploid female, three triploid females, and one triploid male. Flow cytometry analysis revealed multiple ploidy in the gonadal tissue of both sexes of triploids. This is the first examination of gonad ploidy in feral triploids, and we provide evidence that although some triploid grass carp may produce gametes, viable offspring would be produced only under extremely unlikely conditions.

Assessing impacts of introduced aquatic species: Grass carp in large systems

Introduced species have created environmental benefits and unanticipated disasters so a priori assessments of species introductions are needed for environmental management. A checklist for assessing impacts of introduced species was developed from studies of introduced species and recommendations for planning introductions. Sterile, triploid grass carp (Ctenopharyngodon idella) are just beginning to be used as a biocontrol agent for the management of aquatic vegetation in open waterways. Potential impacts of grass carp in open systems were identified by reviewing grass carp biology relative to the impact assessment checklist. The potential consequences of introduced grass carp were reviewed for one case study. The case study demonstrated that conclusions about potential impacts and monitoring needs can be made despite incomplete information and uncertainty.

鹿児島県上甑島の，塩分が異なる２つの汽水湖における大型底生動物相

Quantitative seasonal samplings of macrobenthos were carried out in two brackish lakes with different salinity in Kamikoshiki Island, Kagoshima Prefecture.At Lake Kazakiike, where chlorinity of the water was around 1 ‰ macrobenthic fauna was constructed mostly with chironomid larvae and oligochaetes, which were presumably fresh form, and some brackish and one marine species were added to the fauna. At Lake Kaiike, where surface water usually showed 10 ‰ chlorinity, all species were marine.The population density of macrobenthos was high in autumn and low in summer in both lakes. Dominant species changed at each depth among bivalves and polychaetes in Lake Kaiike.Common brackish species were characteristically absent in both Lake Kazakiike and Lake Kaiike. The author assumed that the absence of open waterways from the lakes into both fresh and marine region was responsible for the lack of brackish species in both lakes.