Physical-chemical Parameters Of Water Research Articles

ENVIRONMENTAL ASSESSMENT OF POLYCULTURE FARMING PRACTICE BASED ON MACROBENTHIC ASSEMBLAGES: A STUDY CASE AT COASTAL AREA OF KALIWUNGU, KENDAL (CENTRAL JAVA, INDONESIA)

The purpose of this study was to determine environmental quality parameters using number of species, diversity and similarity of macrobenthic communities. This study was conducted at two locations, the Location I was a polyculture farming area, farming milkfish (Chanos Chanos) and black tiger shrimp (Penaeus monodon) and seaweed Gracilaria sp. in the coastal area of Mororejo, Kendal District, Central Java. Location II was the coastal area of PT. Plywood Indonesia, which is located adjacent to industrial activities as well as directly affected the tide. Systematic random sampling was employed, measuring physical-chemical parameters of water and sediment. Samples of macrobenthos were taken from the sediment. Data was analysed using diversity and evenness indices approach. Samples of macrobenthos were taken from the sediment using Eckman grab, then was analysed using diversity and evenness indices approach. Results showed that the Location I was dominated by Cerithidea cingulata and Terebralia sulcata (Potamididae), Minima batillaria (Batillaridae). The Location II was dominated by Cirratulus sp., Cirriformia sp. and Aphelochaeta (Cirratulidae) and Prionospio sp. (Spionidae), which are considered as indicators of disturbed area. This results implied that the use of area for both polyculture and industrial activities may lead to environmental disturbance, thus environmental coastal management need to be applied in regular basis, both temporally and spatially.

The role of environmental factors for the composition of microbial communities of saline lakes in the Novosibirsk region (Russia).

BackgroundNothing is currently known about microbial composition of saline lakes of the Novosibirsk region and its dependence on physical-chemical parameters of waters. We studied the structure of microbial communities of saline lakes of the Novosibirsk region and the effect of physical-chemical parameters of waters on microbial communities of these lakes.ResultsAccording to the ion content, the lakes were classified either as chloride or chloride-sulfate types. Water salinity ranges from 4.3 to 290 g L−1. Many diverse microbial communities were found. Filamentous and colonial Cyanobacteria of the genera Scytonema, Aphanocapsa, and/or filamentous Algae dominated in littoral communities. Spatial and temporal organization of planktonic microbial communities and the quantities of Archaea and Bacteria were investigated using fluorescent in situ hybridization. We have found that the dominant planktonic component is represented by Archaea, or, less frequently, by Bacteria. Various phylogenetic groups (Bacteria, Archaea, Algae, and Cyanobacteria) are nonuniformly distributed. The principal component analysis was used to detect environmental factors that affect microorganism abundance. We found the principal components responsible for 71.1 % of the observed variation. It was demonstrated that two-block partial least squares was a better method than principal component analysis for analysis of the data. We observed general relationships between microbial abundance and water salinity.ConclusionsWe have performed the first-ever study of the structure of the microbial communities of eleven saline lakes in the Novosibirsk region along with their physical-chemical parameters of waters. Our study demonstrates that saline lakes in the Novosibirsk region contain a unique microbial communities that may become a prolific source of microorganisms for fundamental and applied studies in various fields of ecology, microbiology, geochemistry, and biotechnology, and deserve further metagenomic investigation.

Ecological guilds of epiphytic diatoms (Bacillariophyta) on Acrostichum danaeifolium Längst. & Fisch in a subtropical wetland in southern Brazil

Abstract Aim: Seasonal patterns diatom community on Acrostichum danaeifolium were examined in a wetland in southern Brazil. Methods The adhered diatoms were removed from the plant, species identification and growth forms were performed, and determined physical-chemical parameters of water. Results In total, 96 taxa belonging to 46 genera were identified. Nitzschia frustulum, Pseudostaurosira brevistriata and Plagiogramma tenuissimum were abundant species. Distinct growth forms that formed low-and high-profile ecological guilds and a mobile guild were observed. Navicula and Nitzschia were the genera with the greatest number of species, and these diatoms formed mucilage tubes. The water temperature varied from 10-26 °C, the depth from 0.35-0.80 m, the transparency from 0.20-0.23 m, the flow from 9.4-42.12 m3 s–1, the pH from 7.08-8.89, the electrical conductivity from 0.65-15.83 mS cm–1, the total organic phosphorus from 0.03-0.11 mg L–1, and the total organic nitrogen from 0.29-0.49 mg L–1. In summer, marine species such as Thalassiosira eccentrica and Rhaphoneis castracanii were also present. Conclusions The high-profile guild prevailed in all seasons of the year, with higher number of growth forms in the guild in winter. The richness found on A. danaeifolium shows that this plant provide a favorable habitat for epiphytic diatoms in wetlands such as Lagoa Pequena.

LA RELACIÓN ENTRE PELTIGERA SP. Y RHIZOPHORA MANGLE EN ARROYO DE PLATA (BOLÍVAR), CARIBE COLOMBIANO

Objective: To determine the distribution and status of mangrove stands in Arroyo de Plata (Department of Bolivar). Methodology: Field work was conducted through woodland, using biological sampling of the flora and the physical and chemical parameters of water and soil along transects within the forest. Results: The composition of the stand includes five species, Rhizophoramangle (red, colorao or colorado mangrove), Avicenniagerminans (salty, dark color, black or iguanero mangle) Laguncularia racemosa (white, yellow or bobo mangrove), Conocarpus erecta (zaragoza mangle) and Pelliciera rhizophorae (tea mangrove). The lichen (Peltigera sp), was found associated with the pioneer species (R. mangrove) whose relationship is carried out only when the mangrove is in a state of degradation and the physical-chemical parameters of water and soil, are extreme. Conclusion: Mangroves showed mature coastal basin type mixed characteristics, where the invasive species P. rhizophorae has the highest IVI due to its high density. Registration of Peltigera sp lichens and its presence of the Colombian Caribbean mangrove is not only the first for this region, its distribution may be restricted to the coastal zone, it is incidental and demonstrates its ability to adapt to environmental changes, and can be considered between the bio-indicators of environmental characteristics, especially of the the current alterations of soil and water.

The effects of physical-chemical water parameters on the Nymphaeion alliance development in northwestern Serbia

<em>Nymphaeion</em> alliance vegetation is dominant floating-leaved vegetation in the Danube–Tisza–Danube hydrosystem in northwestern Serbia and comprises <em>Nymphaeetum albae</em>, <em>Nymphaeetum albo-luteae</em>, <em>Nymphoidetum peltatae</em> and <em>Trapetum natantis</em> associations. Comparative analysis of physical-chemical water parameters on localities where these – in most parts of Europe endangered and vulnerable stands – develop showed that most phytocenoses are associated with specific habitat conditions. Of the analyzed water properties, the factors that cause <em>Nymphaeion</em> alliance phytocenoses differentiation are primarily pH, alkalinity and COD-MnO<sub>4</sub>. Formation of the <em>Nymphaeetum albae</em> stands is significantly associated with the highest values of pH, COD-MnO<sub>4</sub> and alkalinity, and the lowest nitrate, nitrite, dissolved and the total phosphorus content values, in comparison to the other studied associations. <em>Nymphoidetum peltatae</em> stands develop in waters characterized by the lowest pH and COD-MnO<sub>4</sub>, low alkalinity, and the highest nitrate and nitrite values in relation to the other analyzed phytocenoses. <em>Trapetum natantis</em> stands, on the other hand, prefer the warmer sections of the canal network, neutral pH, and the highest values of BOD<sub>5</sub>, dissolved and total phosphorus. Habitat conditions in which <em>Nymphaeetum albo-luteae</em> stands develop are of the widest range in comparison to other investigated phytocenoses.

Bioindicador Ceriodaphnia dubia aplicado na avaliação ecotoxicológica da água da bacia hidrográfica do rio Una

The majority of the Una River Basin is located in Taubate County and contributes significantly to its water supply. The main goal of this research was to evaluate the water quality of the Una River using the microcrustacean C. dubia as bioindicator for tests of chronic and acute toxicity. Bimonthly water samples were obtained from each of six localities throughout the Una Basin, from March to October, 2011. Physical-chemical water parameters such as pH, electrical conductivity, hardness, dissolved oxygen and precipitation were measured and correlated to the C. dubia reproductive rates. No significant relationships were found between the water’s electrical conductivity and precipitation with respect to bioindicator reproductive rates. However, at the Sete Voltas, Antas and Rocinha Sub-Basins, significant interactions were detected between some water parameters and reproductive rates, suggesting that water may constrain the reproduction of C. dubia. Acute toxicity was not detected in any of the six sites, while chronic toxicity was recorded at Rocinha, Sete Voltas, Antas, Medio and Baixo Una Sub-Basins. In general, the water quality of the Una Basin, as indicated by the absence of acute toxicity, still remains in an acceptable conservation condition. Caution is needed, however, since slight pollution sources are causing chronic toxicity in some localities. In addition, as the microcrustacean C. dubia, appeared to be a reliable bioindicator in this investigation, we suggest that it be used for continuous water quality monitoring programs.

Ecology of horn snail (Telescopium telescopium, Linnaeus 1758) on mangrove ecosystem of Pantai Mayangan, West Java

Abstract. Rahmawati G, Yulianda F, Samosir AM. 2013. Ecology of horn snail (Telescopium telescopium, Linnaeus 1758) on mangrove ecosystem of Pantai Mayangan, West Java. Bonorowo Wetlands 3: 41-49. The aim of this research was to know the influence of mangrove and abandoned ponds on the growth and population of horn snail (Telescopium telescopium, Linnaeus 1758) at Pantai Mayangan, Legon Kulon Subdistrict, Subang District, West Java. The study was conducted from May to October 2011 with monthly sampling intervals. Sampling was done in two places: abandoned pond (station 1) and mangrove area (station 2). Each station consists of 3 replications, using 1 x 1 m2 transects. Physical-chemical water parameters are measured in situ, whereas TDS, TSS, and COD are measured in the Laboratory of Productivity and Aquatic Environment, Bogor Agricultural University, Bogor. The bottom substrate was sampled in the first month and last month of the study and was analyzed at the Soil Science Routine Laboratory, Bogor Agricultural University, Bogor. The results showed that the density of horn snail population in mangrove areas was lower than in abandoned ponds. Based on Morisita’s index, the horn snail distribution pattern is uniform, random, and clumped. Horn snail has a negative allometric growth pattern with b <3, i.e., long growth is more dominant than weight growth. The condition factor of horn snails in abandoned ponds is higher than in mangrove areas. Physical-chemical water parameters generally support horn snail growth. The horn snail meat index indicates that the meat is lower than the shell weight. Horn snail can be managed by increasing the volume of pond water, recirculation system, use of pond or sedimentary channel to cope with low dissolved oxygen, mangrove planting to maintain ecosystem balance, and horn snail catching in abandoned pond area which has high horn snail density

Habitat Variation in Vernal Pool Ecosystems on Both Sides of the Strait of Gibraltar

Lumbreras, A.; Tahiri, H.; Pinto-Cruz, C.; Pardo, C., and Molina, J.A., 2012. Habitat variation in vernal pool ecosystems on both sides of the Strait of Gibraltar. We studied vernal pool (VP) ecosystems along a latitudinal gradient crossing the Strait of Gibraltar in order to determine its role in the distribution of VP plant communities. We analyzed flora, vegetation, physical–chemical water parameters, and climatic data from two vernal pool areas on both the European (Iberian) and African (Moroccan) sides of the Strait. Despite the minor distance between both territories, the pools clearly differed in species composition and ecology. However, they showed a similar vegetation zonation in growth forms, including isoetid, batrachiid, and helophytic vegetation. The distribution of the plant communities was related to nutrient load, temperature, and precipitation. Water nitrate concentration was higher in Morocco, where VPs are characterized by Isoetes velata subsp. adspersa and Ranunculus saniculifolius communities. Iberian VPs had lower water nitrate content, and were characterized by Isoetes velata subsp. velata and Ranunculus peltatus communities. We think this nutrient difference is likely to be caused by the different land management regime on each side of the Strait, with more intensive agriculture in Morocco. Long-term (historical) and present-day (ecological) processes have been proposed to account for the habitat variation in vernal pool ecosystems on both sides of the Strait of Gibraltar.

POTENTIAL ROLES OF BIOTIC FACTORS IN REGULATING ZOOPLANKTON COMMUNITY DYNAMICS IN JAKARTA BAY SHALLOW WATER COASTAL ECOSYSTEM

<p>The dynamics in zooplankton abundance were regulated by changes in water physical-chemical parameters and interaction with biotic factors. In this research we examined the relationship between zooplankton community dynamic and important biotic factors, such as predation and food availability, in Jakarta bay. Plankton samplings were done in 10 sampling stations in Jakarta bay, from July to November 2009. Zooplankton samples were collected using horizontal towing method with NORPAC plankton net (mesh size 300 μm). Salinity, water depth, water temperature, and water transparency were measured. Phytoplankton samples were also collected with the same method as zooplankton, using Kitahara plankton net (mesh size 80 μm). Zooplankton taxas were grouped into two groups, the prey and predatory zooplankton. The results showed that there were two different patterns in zooplankton groups dynamic i.e., the single and double peak. The abundance peak in most zooplankton groups, such as copepods, cirripeds, luciferids, and tunicates, were induced by the high food availability during the phytoplankton bloom in August. The high abundance of prey zooplankton groups in August was responded by the predatory zooplankton groups, resulting in high abundance of predatory zooplankton in adjacent month. The high abundance of ctenophores and chordates (fish larvae) were suggested as the main factor for the low abundance of other zooplankton in September. Physical and chemical factors were not the regulating factors due to the stability of those factors during this research period. Thus we concluded that food availability and predator-prey interaction were the main factors which regulate zooplankton community dynamics in Jakarta bay.</p><p>Keywords: predator-prey interaction, zooplankton, abundance peak, food availability, phytoplankton bloom</p>

POTENTIAL ROLES OF BIOTIC FACTORS IN REGULATING ZOOPLANKTON COMMUNITY DYNAMICS IN JAKARTA BAY SHALLOW WATER COASTAL ECOSYSTEM

The dynamics in zooplankton abundance were regulated by changes in water physical-chemical parameters and interaction with biotic factors. In this research we examined the relationship between zooplankton community dynamic and important biotic factors, such as predation and food availability, in Jakarta bay. Plankton samplings were done in 10 sampling stations in Jakarta bay, from July to November 2009. Zooplankton samples were collected using horizontal towing method with NORPAC plankton net (mesh size 300 μm). Salinity, water depth, water temperature, and water transparency were measured. Phytoplankton samples were also collected with the same method as zooplankton, using Kitahara plankton net (mesh size 80 μm). Zooplankton taxas were grouped into two groups, the prey and predatory zooplankton. The results showed that there were two different patterns in zooplankton groups dynamic i.e., the single and double peak. The abundance peak in most zooplankton groups, such as copepods, cirripeds, luciferids, and tunicates, were induced by the high food availability during the phytoplankton bloom in August. The high abundance of prey zooplankton groups in August was responded by the predatory zooplankton groups, resulting in high abundance of predatory zooplankton in adjacent month. The high abundance of ctenophores and chordates (fish larvae) were suggested as the main factor for the low abundance of other zooplankton in September. Physical and chemical factors were not the regulating factors due to the stability of those factors during this research period. Thus we concluded that food availability and predator-prey interaction were the main factors which regulate zooplankton community dynamics in Jakarta bay.Keywords: predator-prey interaction, zooplankton, abundance peak, food availability, phytoplankton bloom

Photocatalytic Degradation of Pesticides in Natural Water: Effect of Hydrogen Peroxide

The aim of this paper is to evaluate the effectiveness of photocatalytic treatment with titanium dioxide in the degradation of 44 organic pesticides analyzed systematically in the Ebro river basin (Spain). The effect of the addition of hydrogen peroxide in this treatment is studied, and a monitoring of effectiveness of photocatalytic processes is carried out by measurements of physical-chemical parameters of water. The application of photocatalytic treatment with 1 g L−1of TiO2during 30 minutes achieves an average degradation of the studied pesticides of 48%. Chlorine demand, toxicity, and dissolved organic carbon (DOC) concentration of water are reduced. If hydrogen peroxide is added with a concentration of 10 mM, the average degradation of pesticides increases up to 57%, although chlorine demand and toxicity of water increase while DOC concentration remains unchanged with this treatment. The application of either photocatalytic treatments does not produce variations in the physical-chemical parameters of water, such as pH, conductivity, colour, dissolved oxygen, and hardness. The pesticides which are best degraded by photocatalytic treatments are parathion methyl, chlorpyrifos, α-endosulphan, 3,4-dichloroaniline, 4-isopropylaniline, and dicofol while the worst degraded are HCHs, endosulphan-sulphate, heptachlors epoxide, and 4,4′-dichlorobenzophenone.

Comparative Study of Water Quality at Different Peat Swamp Forest of Batang Igan, Sibu Sarawak

Problem statement: It is important to find the status of water qualit y at converted peat swamp forest into oil palm plantation. This study w as conducted to find and determine the water quality at peat swamp forest of Batang Igan, Sibu S arawak. This study presents a status on the water quality of peat swamp forest at the area. Approach: In-situ data and a total of 72 water samples were collected at four sampling stations (S1, S2, S3 and S4) in three different months of July, August and November 2009. In-situ data included temperature, conductivity, Dissolved Oxygen (DO), pH and Turbidity. Analysis for ammoniacal nitrogen (NH 3-N), Biological Oxygen Demand (BOD), Chemical Oxygen Demand (COD) and Total Suspended Solids (TSS) were conducted in the laboratory. Results for water quality parameters are as follows, temper ature range (26.85-32.90 °C), pH range (3.03-3.84), DO range (1.99-8.05 mg/L), conductivity (42.07-98.72 µS cm -1 ), TSS range (1-54 mg L -1 ), turbidity (0.39-9.80 NTU), BOD range (0.5-9.8 mg L -1 ), COD (0-17) and ammoniacal nitrogen (0.2-0.42 mg L -1 ). The Water Quality Index (WQI) which was calculated based on six water quality parameters namely dissolved oxygen, biological oxygen demand, chemical oxygen demand, pH, ammoniacal nitrogen and total suspended solids, was representa tive of the state of water quality in Batang Igan p eat swamp forest. Results: Based on WQI, S1 was categorized under Class III while S2, S3 and S4 were categorized under Class II. Conclusion: The physical-chemical parameters of water in Batan g Igan peat swamp forest were in normal range or in class I and class II that is in good water status except for pH and dissolved oxygen for the water; however it i s normal condition for peat water.

WATER PARAMETERS EVOLUTION IN A HYDROELECTRIC SITE

This study presents the impact of the cascade arrangement of the hydropower plants of reversible bulb turbines (HPP) belonging to Lower Olt River, in south of Romania, on water quality. A comparative analysis of the water quality is performed for period of ten years of continuous operation of the hydro electrical site. The water physical-chemical parameters are considered and important issues over the water quality are studied: the support of aquatic environment, the hydro turbines impact, the pollutants storage, the water hardness influence over turbines and the environmental impact of hydropower plants operation.

Influence of geology in the geochemistry signature of Itacolomi State Park waters, Minas Gerais-Brazil

In all geological scenarios, mineral water reactions will affect the water chemistry. As such, water resources in different rocks commonly involve different hydrogeological compartments. The aim of this work is to evaluate the influence of geology in the geochemistry signature of Itacolomi State Park waters. To do so, a survey of the geological units in the area was carried out, a geological/stratigraphic division was made, and its correlation with the main geological events was determined. Using the advantages of GIS, all the catchments were delimited. Based on this division, near 30 stream and lake segments were chosen for analyses. In each point, all physiochemical properties of the water were measured, and samples were collected to determine the concentrations of major and trace elements by ICP–OES. The dynamics of the Itacolomi State Park rock-soil and stream water solutions suggest that mixing of drainage waters from different bedrock and soil sources regulates stream water physical–chemical parameters and solute concentrations. The analytical data showed a clear correlation between the chemical compositions of the solute and the geological characteristics of the catchment. Units that are covered by iron oxide hardpan (Manso unit) and iron-banded formations (Custodio unit) show a large amount of soluble elements, including high values of Fe and Mn. On the other hand, the presence of high values of Al and K (Itacolomi unit) are a direct consequence of the presence of quartzite associated with low pH values.

Winter phytoplankton communities in different depths of three mesotrophic lakes (Łęczna-Włodawa Lakeland, Eastern Poland)

AbstractPhytoplankton samples were collected from three mesotrophic lakes: Piaseczno, Rogóźno and Krasne during winter seasons (from January to March). The samples were analyzed for species analysis and abundance of planktonic algae in relation to different depths of water column (0–7 m). Selected water physical-chemical parameters were also measured. Abundance of phytoplankton depended strongly on the thickness of snow and ice cover or mixing conditions. The maximal phytoplankton total number reached about 5 × 106 ind. L−1 beneath the clear ice in the Krasne Lake, minimal numbers were recorded under the thick snow and ice layers in the Piaseczno Lake (2 × 103 ind. L−1). The winter phytoplankton communities were dominated by flagellates principally cryptomonads (Cryptomonas spp. Rhodomonas minuta), euglenophytes (Trachelomonas volvocina, T. volvocinopsis), dinoflagellates (Peridinium bipes, Gymnodinium helveticum) and chrysophytes (Mallomonas elongata, M. akrokomos, Dinobryon sociale) or non-motile small species of blue-green algae (e.g. Rhabdoderma lineare, Limnothrix redekei), diatoms (Stephanodiscus spp., Asterionella formosa), and green algae (e.g. Scenedesmus spp., Monoraphidium spp.). Phytoplankton abundance and structure showed differentiation during the winter season and along the water column as well.

Diatoms as indicators of isolated herbaceous wetland condition in Florida, USA

Abstract Benthic, epiphytic, and phytoplanktonic diatoms, as well as soil and water physical–chemical parameters, were sampled from 70 small (average 0.86 ha) isolated depressional herbaceous wetlands located along a gradient of human disturbance in peninsular Florida to (1) compare diatom assemblage structure between algal types; (2) develop biological indicators of wetland condition; (3) examine synecological relationships between diatom structure and environmental variables, with the ultimate goal of developing an index of biological integrity using a single assemblage. Collected diatom samples were enumerated to 250 valves and identified to species or subspecies. An assessment of wetland condition was made using a landscape-scale human disturbance score (Landscape Development Intensity index, LDI), calculated for each site using land use maps and GIS. Assemblages from both impaired and reference sites were compared using blocked multi-response permutation procedures, the percent similarity index, and visually examined using non-metric multidimensional scaling (NMDS). No ecologically significant compositional differences were found within sites. Mantel's test (Mantel's r = 0.29, p 0.50, p Metrics to assess wetland condition were developed using epiphytic abundance data. Epiphytic taxa sensitive or tolerant to human landscape modification were identified using Indicator Species Analysis, and autecological indices relating diatom sensitivity to nutrients, pH, dissolved oxygen levels, saprobity, salinity, and trophic status were calculated. Fourteen final metrics were identified, scored on an ordinal scale, and combined into the Diatom Index of Wetland Condition (DIWC). The DIWC was highly correlated with the disturbance score (Spearman's rs = −0.71, p

Farelo de mandioca (<em>Manihot esculenta</em>) Crants em substituição ao milho (<em>Zea mays</em> L.) em rações para alevinos de carpa-capim (<em>Ctenopharyngodon idella<em>)

The experiment was carried out aiming to evaluate different substitution levels of corn by cassava meal in grass carp ctenopharyngodon idella fingerlings diets. It was used 120 fingerlings with initial live weigh of 2.51+0.05 g, distributed in 24 net ponds at a randomized blocks design with six treatments and four replications, each block corresponding to a fiber-ciment 1000 L tank with six net ponds (120 L) inside. Each net ponds with five fingerlings was considered an experimental unit. The treatments consisted in rations (32% crude protein and 3000 kcal/kg digestible energy) with different cassava meal inclusion levels of (0.00, 5.99, 11.98, 17.97, 23.95, 29.94) corresponding a 00.0, 20.0, 40.0, 60.0, 80.0 e 100.0% of replacement of corn. Effect were not observed of cassava-by-product meal inclusion levels on the final weight, final length, feed: gain, condition index and survival rate of grass carp ctenopharyngodon idella fingerlings. The water physical-chemical parameters were 22.92oC, 24.54oC 6.38 mg/L, 7.47 e 0.16 ms/cm, respectively to morning temperature, afternoon temperature, dissolved oxygen, ph and electric conduct. It may be concluded that the cassava meal can substitute the corn in even 100% in grass carp fingerlings diets

Densidade de estocagem de juvenis de tambaqui durante a recria em tanques-rede

O objetivo deste trabalho foi determinar a densidade de estocagem mais adequada para a fase de recria de juvenis de tambaqui (Colossoma macropomum) em tanque-rede. Foram utilizados 12 tanques-rede de 1 m³ cada, com peixes distribuídos nas densidades de 200, 300, 400 e 500 peixes/m³ em três repetições. Os peixes foram alimentados seis vezes por semana em três refeições diárias com ração comercial com 36% de proteína bruta, durante 60 dias. Foram analisados o crescimento em peso e em comprimento, o coeficiente de variação do comprimento, a taxa de crescimento específico e a glicose sanguínea aos 30 e 60 dias de criação. Ao final do experimento, foram analisados os seguintes parâmetros de produtividade: sobrevivência, conversão alimentar aparente, ganho de peso e produção por área. Os parâmetros físico-químicos da água foram avaliados a cada sete dias. O crescimento em peso e em comprimento, aos 60 dias, foi maior na densidade de 200 peixes/m³ do que na de 500 peixes/m³. O coeficiente de variação, a taxa de crescimento específico e a glicose não diferiram entre as densidades aos 30 e 60 dias. A sobrevivência final, a conversão alimentar aparente e o ganho de peso foram iguais em todas as densidades. A produção por área foi significativamente maior nas duas maiores densidades. Os resultados indicaram que a densidade de 400 peixes/m³ é a mais adequada para recria de juvenis de tambaqui em tanque-rede.

Purification of a contaminated thermal well at an oil drilling site

The thermal water from the well MT-4 in Northeast Slovenia contains many organic micropollutants of geogenic origin because of the nearby oil fields. Therefore, a special technological treatment was necessary to make the water suitable for bathing: consisting of flocculation, sand filtration, and adsorption on granular activated carbon. We managed to remove not only all potentially toxic organic substances, but also the mesophilic bacteria (CFU) as well as sulfite reducing bacteria. On the other hand, all the important physical chemical parameters of water remained practically unchanged. In this way a hygienic water quality for balneological purposes was obtained. ©1999 John Wiley & Sons, Inc. Environ Toxicol 14: 211–216, 1999

An artificial stream mesocosm to simulate fate and effects of chemicals: Technical data and initial experience with the biocenosis

An artificial stream system is described which has been installed at the Fraunhofer Institute to simulate fate and effects of environmental chemicals in relevant water compartments. The artificial stream is part of the institute's outdoor field simulation facilities for studies with radio-labelled substances. The circular stream system has a length of about 35 m, a width of 0.6 m, a depth of 0.35 m and is made of stainless steel to avoid contaminations. Two inlets and an extended segment diversify the current. Current is generated by electrically-driven steel paddles which allows a regulation of velocity. The artificial stream is filled with sediment (about 2.5 m 3) and water (approx. 3 m 3) from a small natural stream. Each of the inlets contains an aquatic lysimeter with an undisturbed sediment core of 0.6 m diameter and 0.6 m column height, which is flanged at the bottom of the water basin. This design allows the study of fate of substances in the ecosystem compartments water, sediment and water leaching through the river bed. A preliminary study was performed comparing various physical-chemical water parameters and the development of the biocenosis in the natural and the artificial stream in order to determine whether the natural stream can serve as reference stream in experiments. Following an adaptation period of 4–8 weeks, macroinvertebrate species diversity and population densities were similar in both streams. Therefore, it is concluded that the natural stream can be used as control in future investigations. Exposure studies are planned including investigations of adverse effects of contaminants on organisms transferred to the artificial stream from a natural water.