Showing papers in "Studies in Environmental Science in 1986"
TL;DR: This chapter focuses on some biochemistry related to the adhesion of fouling diatoms to surfaces, and the effect of an inhibitor of glycoprotein synthesis on adhesion should be investigated.
Abstract: Publisher Summary This chapter focuses on some biochemistry related to the adhesion of fouling diatoms to surfaces Cross-feeding in biofilms may involve much more than exchange of organic molecules It could, for instance, involve the detoxification of the biofilm environment by bacterial respiration of photosynthetically-produced oxygen Except where stated otherwise, the experimental organism used in this study was Amphora coffeaeformis (Agardh) Kutz A coffeaeformis has been shown to respond to a glucose gradient in agar by moving up the concentration gradient In the absence of glucose, cells move in a series of random ellipses The fact that the cytochemical work of Daniel et al showed the diatom adhesive polymer to be an acid polysaccharide and the subsequent finding that an inhibitor of protein synthesis prevented adhesion, suggested that the effect of an inhibitor of glycoprotein synthesis on adhesion should be investigated
49 citations
TL;DR: The results to date with RTV silicone elastomers indicate them to be worthy of more study as nonbiocidal antifouling systems, and Amphora was chosen for laboratory studies because of its importance in shipfouling and for its ease of culturing and rapid attachment to surfaces.
Abstract: Publisher Summary This chapter elaborates the control of fouling by nonbiological systems. The impact of fouling includes the loss of efficiency of ships, buoys, pilings, offshore platforms, sonar domes, and a variety of piping systems. Fouling has been controlled traditionally by antifouling paints that prevent settlement of organisms through the release of biocides, chiefly metallic e.g., copper, or organometallic compounds e.g., triorganotins. Amphora was chosen for laboratory studies because of its importance in shipfouling and for its ease of culturing and rapid attachment to surfaces. In spite of being derived from a clonal culture, differences in the adhesive capacity of cells between cultures occur. The results to date with RTV silicone elastomers indicate them to be worthy of more study as nonbiocidal antifouling systems. Their physical properties of poor abrasion resistance and tear strength limit the range of possible applications to situations where such characteristics are not of primary importance e.g., aquaculture, offshore structures, piping systems and power station water intakes.
29 citations
TL;DR: A survey of slime formation of antifouling paints can be found in this paper, where the authors explain the world-wide survey of the formation of slime forming of paint.
Abstract: Publisher Summary This chapter explains the world-wide survey of slime formation of antifouling paints Microbial slime films have been shown to increase significantly the drag of objects in contact with moving seawater Small growths of Tubularla indivisa were found on the organotin varnishes and during 1984 patches of Achanthes subsessilis were also present Fouling growth on nontoxic submerged surfaces can be immense even within two months as seen at certain sites in the present study Although the test areas employed were very small, fouling development was consistent from one year to the next and followed the same pattern as that observed on large test areas immersed at certain sites Laboratory studies on biocide resistance (particularly using mixed combinations of biocides) are needed on those diatoms found to flourish on antifouling paint surfaces Such data combined with the analysis of paint leachates will improve theunderstanding of the biology of fouling organisms
28 citations
TL;DR: Monitoring in tributaries of a small eutrophic prairie stream with agricultural watershed subject to extensive soil erosion found diatom-dominated biofilm communities developed in one-month periods over two years with generally less trapped sediments in the early spring than sites downstream.
Abstract: Diatom-dominated biofilm communities which developed in one-month periods over two years were monitored in tributaries of a small eutrophic prairie stream with agricultural watershed subject to extensive soil erosion. Site A, which was spring fed, had a year-round flow, the highest silica and nitrate-nitrogen levels, and a distinct diatom community regardless of the season with generally less trapped sediments in the early spring than sites downstream. All communities (Sites A-E) had at least two tiers existing side by side on the primary glass substrates: a prostrate tier of pennate diatoms, attached or motile, with their valve surfaces parallel to the substrate; and a second tier of pennate species attached by a proximal apical pole perpendicular to the primary substrate. At all sites, but particularly the downstream sites, the communities were surrounded and/or covered by sediments held by mucilages of dominant and codominant diatom species and bacteria of the first two tiers. Second tier (perpendicular) life-forms included rosettes of Surirella ovata , individual Navicula lanceolata , clumps or rows of Gomphonema parvulum , rosettes of Synedra ulna , clumps or rosettes of Eunotia curvata , and fan-like aggregates of Meridion circulare forming hemispherical colonies. Some diatoms of this tier were not attached directly to the artificial substrate but to other diatoms or to bound particulates. Filamentous bacteria were particularly important in tying together clumps of organisms and sediments in tiers 1 and 2, at sites C and D. A third tier consisted of filamentous organisms, e.g. Oedogonium sp. (Chlorophyceae), a stalked diatom Gomphonema sp., and protozoans including stalked peritrichs, which developed intermingled with the first two tiers and directly attached to the glass substrate. Secondary attachment of Gomphonema and Synedra to filaments of the third tier occurred, but this tier was never sufficiently populated or stable enough to trap and hold a layer of sediments. A species of diatom could occupy only one tier ( Achnanthes lanceolata , tier 1; Synedra ulna, Synedra acus tier 2), or more than one tier if its growth habit included structural and/or functional heteromorphy. Diatom life-forms are illustrated, as are bacteria in their associations with the diatom-dominated communities.
26 citations
TL;DR: In this article, the main weathering processes are due to the combined action of rainwater and atmospheric pollutants (particularly the carbonaceous particles due to combustion) deposited on the surface of the monument.
Abstract: The problem of the conservation of historical monuments (statues, columns, ancient buildings) requires an accurate study of the many environmental agents which bring about the deterioration process and affect the actual rate of deterioration. Among the most active causes of weathering, we can cite: (i) the weakening of the outer layer of the art work, which is caused by complex microphysical effects and is in particular due to wetting of the monument (a comparison between the effects of rainwater and condensation is made); (ii) the chemico-physical action of pollutants captured in both the dry and wet phase. the destructive processes depend on many factors: the past history of the monument, the capture and nature of the pollutants, and the frequency of some microclimatic conditions, particularly those supplying the water necessary for chemical reactions. to this end studies of diurnal and seasonal variations on the monument of both the heat wave and the fluxes of moisture and energy are very important. Some of these processes have been shown with microclimatic studies and microphysical investigation associated with mineralogic and chemical analyses of samples of weathered material. Mathematical models in some cases (especially for solarradiation and temperature) permit physical simulation, reconstruction of past data and extrapolation into the future observation of many monuments from different epochs, situated at various sites, gives examples of the fundamental processes that are often associated with, or masked by, other effects. The main weathering processes are due to the combined action of rainwater and atmospheric pollutants (particularly the carbonaceous particlesdue to combustion) deposited on the surface of the monument. The way in which the surface is wetted is very important: in fact, as hortdrizzle can activate the dry deposit without washing it away, and i n this case the pH of rain dro plets is of secondary importance; on the other hand, showers supply abundant water which favours dissolution of the stone and removal of the solute, resultingin athinning of the original rock. Another important factor is the dynamic regime (i. e. laminar or turbulent) of the water flowing over the surface of the monument. In zones where the surface of marble or calcareous monuments is only wetted, but protected from run-off, black crusts (characterized by crystals of gypsum and calcite with carbonaceous particles embedded in the crusts) are formed. Zones subjected t o heavy run-off are also subjected to a thinning of the rock and small authentic calcite crys tals form that are white in appearance. In the case of relatively unpolluted towns, where marble and limestone sulphation is not the main cause of the deterioration process, biological deterioration mechanisms are often very important, due to the activity of epilithic and endolithic microflora and microfauna. The case of particularly precious mortars, i.e. mals or frescces, is discussed in order to clarify the thermodynamic mthcd proposed for the analysis of qrimental campaigns. Finally actions are described that act on the causes and not only an the effects.
26 citations
TL;DR: In this paper, the effects of fluorides on various oral microorganisms including Streptococcus, Actinomyces, Candida, Pseudomonus, Bacteroides and Fusobacterium were examined.
Abstract: The purpose of this study was to examine the effects of fluorides on various oral microorganisms including Streptococcus, Actinomyces, Candida, Pseudomonus, Bacteroides and Fusobacterium , on the acid production of Streptococcus mutans (S mutans ), and on the synthesis of water insoluble glucan catalyzed by extracellular enzyme (glucosyltransferase) derived from S mutans The minimum inhibitory concentrations of fluoride provided as NaF for Actinomyces, Candida and Pseudomonus were higher than those for the other microorganisms NaF arrested bacterial growth bacteriostatically but did not affect the synthesis of water-insoluble glucan Glucan synthesis was inhibited only by CoF 2 at concentrations of 600-1000 ppm F Lactic acid production was suppressed in both the cell resting and cell growing systems Fluorides of bivalent cations such as SnF 2 and CoF 2 inhibited the growth of the microorganisms more markedly than NaF
25 citations
TL;DR: In this paper, it was shown that after 12 weeks of experimental exposure to 194 μg 0 3 /m 3, spruce clone needles exhibited increased intercellular areas associated with increased internal surfaces and raised internal/external surface quotients if compared to the reference trees.
Abstract: If the monitored air pollution values are compared with the air quality criteria it becomes apparent that in many parts of Europe high concentrations of ozone, extremely risky to vegetation, are formed in the summer months (May to September) with their high intensities of solar irradition. After 12 weeks of experimental exposure to 194 μg 0 3 /m 3, spruce clone needles exhibited increased intercellular areas associated with increased internal surfaces and raised internal/external surface quotients if compared to the reference trees. After exposure to 292 μg SO 2 /m 3 over the same period, however, the intercellular system and both the other values were reduced. the histological changes of the Black Forest spruce trees corresponded to the experimentally ozone-induced ones whereas the changes of tissue of the Fichtel Gebirge samples were similar to those recognized after experimental SO 2 exposure. Both the needles of the samples exposed to either O 3 or SO 2 and the needles of the severely damaged field study items exhibited reductions of transpiration and water potential as well as reduced photosynthetic rates; simultaneously the osmotic potentials of all samples were raised due to the raised total sugar contents. Despite of comparatively lower contents of the needles, leaching experiments with Black Forest needles produced higher magnesium and calcium leaching rates than the corresponding experiments with Fichtel Gebirge needles. That the sulfur contents of the Black Forest needles were significantly lower than those of the Fichtel Gebirge items reflects the difference in SO 2 concentrations the two sites are exposed to.
21 citations
TL;DR: Impingement or “raining” of diatom cells from the water column was more important in the recolonization of rock surfaces than direct encroachment from the adjacent attached community.
Abstract: The source of algal colonizers onto rock substrates in a eutrophic reservoir was analyzed during the spring diatom pulse by placing sediment traps in and beyond the periphyton growth zone and by scraping intact surfaces of known age. Impingement or “raining” of diatom cells from the water column was more important in the recolonization of rock surfaces than direct encroachment from the adjacent attached community. Relative to substrate-associated standing crops ( = 2.16 × 104cells mm−2), high densities of planktonic and periphytic diatoms impinged from the water column ( = 5.03 × 103cells mm−2d−1), particularly in the upper (surge) zone. Direct encroachment from immediately adjacent populations contributed very little quantitatively (none detected) or qualitatively (6 rare taxa of 67 total diatom taxa found) to the recolonization of denuded surfaces. Storm-induced turbulence reduced natural periphyton densities by up to 47%, with pseudoperiphytic species (e.g., Fragilaria vaucheriae ) exhibiting greater losses than attached forms. The percentage of nonliving diatoms on rock substrates increased during calm periods, prior to storm events.
21 citations
TL;DR: A simple mathematical model of immigration and growth was used to study diatom accumulation, species composition, and diversity patterns during colonization on clay tiles as mentioned in this paper, and the results indicated that the fastest reproducers also had the fastest immigration rates during later stages of colonization.
Abstract: A simple mathematical model of immigration and growth was used to study diatom accumulation, species composition, and diversity patterns during colonization on clay tiles. Accumulation patterns of dominant species and the entire assemblage were accurately predicted by the model when immigration parameters were iteratively varied to the best fit. The species that were fast immigrators during early stages of colonization were different than those species with high growth rates. However, modelled estimates of maximum immigration rates during colonization indicated that the fastest reproducers also had the fastest immigration rates during later stages of colonization. Field procedures for estimating immigration rates were probably not as accurate as estimates made with the model. Patterns of species composition and diversity were shown to be strongly influenced by the balance created when different species were fast immigrators and fast reproducers.
20 citations
TL;DR: In this article, the direct and indirect effects that algal fouling can have on corrosion and on corrosion protection systems are discussed. But the extent to which algae contribute to processes such as pitting corrosion in the absence of bacteria is not easy to assess because if all the protection systems work properly corrosion should not happen at all.
Abstract: Publisher Summary This chapter elaborates the direct and indirect effects that algal fouling can have on corrosion and on corrosion protection systems. A number of algal/corrosion scenarios can be formulated for different situations depending on the type of corrosion protection adopted. These interactions have been derived largely from laboratory studies and theoretical considerations because direct observations from offshore are limited. Some of the interactions are known to depend upon bacterial activity and it is not clear to what extent algae contribute to processes such as pitting corrosion in the absence of bacteria. The extent to which fouling is a problem offshore is not easy to assess because if all the protection systems work properly corrosion should not happen at all. Generally, despite some initial problems on certain structures, corrosion protection systems have performed well in the North Sea.
18 citations
TL;DR: Dynamic bone histomorphometry has further increased the understanding of the effects of fluoride on intraskeletal mechanisms affecting the structure and metabolism of the bone but it does not allow clear-cut differentiation from metabolic bone disease.
Abstract: Quantitative tetracycline-based analysis of iliac bone biopsy was performed in 17 patients with endemic skeletal fluorosis. All had lived in endemic fluorosis areas since their birth. The mean age was 25.6 years and duration of symptoms 7.6 years. The mean fluoride content of the drinking water was 17.8 ppm and the mean daily intake of fluoride was 26.2 mg. None of the patients had Vitamin D deficiency, intestinal malabsorption or renal dysfunction. Pertinent biochemical findings were: raised plasma levels of fluoride, alkaline phosphatase and iPTH, and increased urinary fluoride excretion. Static and dynamic histomorphometric measurements revealed the profiles of osteomalacia and secondary hyperparathyroidism in varying combinations in all cases. Increases in osteoid volume, osteoid surfaces, osteoid seams width, resorption surfaces and mineralization lag time and decreases in corrected apposition rate, bone formation rates and tetracycline labeled surfaces were the variable features recorded in each case. Dynamic bone histomorphometry has further increased the understanding of the effects of fluoride on intraskeletal mechanisms affecting the structure and metabolism of the bone but it does not allow clear-cut differentiation from metabolic bone disease. Endemic skeletal fluorosis, therefore, may be regarded as a parametabolic bone disease.
TL;DR: It is confirmed that fluoride is one of the chemical agents responsible for inducing echinocyte formation and fluoride accumulation in the erythrocyte membrane led to depletion of calcium in the membrane.
Abstract: Ingestion of fluoride in excess leads to its accumulation in the erythrocyte membrane. The biochemical and structural abnormalities detected are reported in this communication. Blood samples of rabbits administered with 10 mg NaF/kg body weight at 24 hour intervals for varying durations were investigated. Human subjects afflicted with hydrofluorosis were also investigated. Fluoride and calcium contents of serum and erythrocyte membrane were estimated using an ion selective electrode and an atomic absorption spectrometer respectively. The erythrocyte morphology was studied using a scanning electron microscope. The results indicate that fluoride accumulation in the erythrocyte membrane led to depletion of calcium in the membrane. Erythrocytes with spinous projections were at a maximum of 7% in human subjects. However, the number in the rabbit rose from 1% to 9% as the duration of exposure to fluoride was increased from 1-20 months. It was also evident that older erythrocytes were more seriously affected than the newly formed erythrocytes as fluoride accumulation increased. This study has confirmed that fluoride is one of the chemical agents responsible for inducing echinocyte formation.
TL;DR: The algal blofouling of oligotrophic Lake Tahoe refers to the increased growth of attached algae, periphyton, on naturally occurring rock substrata along the shoreline as discussed by the authors.
Abstract: The algal blofouling of oligotrophic Lake Tahoe refers to the increased growth of attached algae, periphyton, on naturally occurring rock substrata along the shoreline. Persistent patterns of periphyton production have been observed and associated with land disturbance (i.e., development) within the watershed. Nutrient bioassays demonstrated productivity can be stimulated with increased availability of nitrogen alone or phosphorus and nitrogen together. Both stream and ground waters have been identified as nutrient loading pathways from the watershed to the lake. Particular activities associated with land disturbance increase nutrient mobility and subsequent loading to Lake Tahoe. These activities are believed to be causal factors affecting the differential accural of periphyton biomass (Chl a ) along the shoreline.
TL;DR: In this article, the development of quantitative design approaches to facilitate the more rigorous demands placed on adsorption systems in such applications is summarized, and some of the challenging areas for future efforts to enchance the efficiency of activated carbon adaption processes for water and wastewater treatment are considered.
Abstract: Contemporary issues and developments relating to the application of activated carbon adsorption processes for water and wastewater treatment are discussed. Consideration is given to the increasingly important role of adsorption as a technology for removing specific target compounds or classes of compounds from waters and wastewaters containing complex mixes of organic substances. The development of quantitative design approaches to facilitate the more rigorous demands placed on adsorption systems in such applications is summarized. Finally, some of the challenging areas for future efforts to enchance the efficiency of carbon adsorption processes for water and wastewater treatment are considered.
TL;DR: In this article, the antifouling performance of different combinations of cuprous and zinc oxides in self-polishing polymer (SPC) paint was tested and the results showed that Nontoxic uncoated panels were more heavily fouled than the test paints and also were fouled by a more diverse range of organisms.
Abstract: Publisher Summary This chapter describes the cuprous and zinc oxides that were compared as additional biocides in self-polishing polymer (SPC) paint —that is,the antifouling performance of different combinations of cuprous and zinc oxides in such was tested. Nontoxic uncoated panels were more heavily fouled than the test paints and also were fouled by a more diverse range of organisms. This included extensive fouling by macroalgae from February until August with highest algal fouling in June and July mainly of Ectocarpus and Giffordia species. Raft trials are a good method of testing a large number of formulations with replication. They are rigorous tests of antifouling activity as they are performed at sites rich in fouling organisms similar to the situation of a ship in harbor, which is where most fouling occurs. A high proportion of the fouling organisms on the SPC test paints were diatoms and they must compete under the influence of seasonal changes as well as in response to the presence of antifouling biocides.
TL;DR: The effect of fluoride and ascorbic acid on serum alkaline phosphatase activity was similar to that on bone fluoride deposition, and a pronounced increase in the enzyme activity was observed especially in the low protein group.
Abstract: Female mice ( Mus musculus , Swiss Websters) fed a diet containing low (4%) proteins were tested for the effects of supplemental fluoride and ascorbic acid on body weight, fluoride deposition in the tibia, and blood composition. The results were compared with those obtained from control mice fed a diet containing normal (27%) protein. At the end of 12 weeks, the animals maintained on the low protein diet showed a 40% reduction in body weight, which was unaffected by supplemental fluoride at 10 ppm. Fluoride administration enhanced the tibia fluoride level by 550% in the low protein group and by 160% in the normal protein group. These increases were markedly diminished in the presence of supplemental ascorbic acid. The effect of fluoride and ascorbic acid on serum alkaline phosphatase activity was similar to that on bone fluoride deposition. A pronounced increase in the enzyme activity was observed especially in the low protein group.
TL;DR: In this paper, the authors evaluate dry and wet deposition of pollutants and their forest growth deterioration effects based on the chemical composition of leaves (pollutants and nutrients), growth increment and litter decomposition.
Abstract: The dying-forest syndrom occupies scientists and foresters in Central Europe It is generally agreed that the atmospheric pollution is a major factor (SO 2, NO x, ozone) causing the damage However, the mechanisms involved in forests deterioration and especially the methods of evaluation of these damages are not completely understood and agreed upon among scientists the evaluation of dry and wet deposition of pollutants and their forest growth deterioration effects should be based on the chemical composition of leaves (pollutants and nutrients), growth increment and litter decomposition
TL;DR: The methods of data analysis adopted to provide information to meet engineering requirements and the distribution of algae on offshore structures in the North Sea are described and compared with the algal fouling on navigation buoys from inshore waters in the Inner Moray Firth.
Abstract: Publisher Summary This chapter explains the methods of data analysis adopted to provide such information to meet engineering requirements and describes the distribution of algae on offshore structures in the North Sea. The offshore algal communities are compared with the algal fouling on navigation buoys from inshore waters in the Inner Moray Firth in north-east Scotland. The fouling on offshore installations in the North Sea has necessitated a regular monitoring of the species composition, extent of cover and marine growth thickness. The thickness measurements are particularly important for estimating the effects of marine growth on hydrodynamic loading. Horizontal banding of algae on floating structures has been reported previously. Six different algal zones extending upward from the waterline were recognized on structures in Langstone and Portsmouth harbors.
TL;DR: Reconciliation of the apparently higher in vitro concentrations and the anticipated lower in vivo observations has been obtained by steady-state modeling of the subcellular partitioning of fluorides into cellular fractions driven by a non-ionic diffusion gradient.
Abstract: Physiologic data of whole plant response to elevated ambient air levels of fluoride would seem inconsistent with concentrations required to affect biochemical mechanisms in vitro. Reconciliation of the apparently higher in vitro concentrations and the anticipated lower in vivo observations has been obtained by steady-state modeling of the subcellular partitioning of fluorides into cellular fractions driven by a non-ionic diffusion gradient. Application of this predictive model to reported literature values and physiologic observations has resulted in an understanding of the sequence of biochemical alterations of metabolism associated with elevated ambient atmospheric concentrations of fluoride. This model can be applied to other environmental pollutants which act as weak acid-base couples and may be used to predict the concentrations of these toxic compounds at subcellular sites. Such a model would provide useful information in studying contemporary problems such as acid rain. Information on the subcellular partitioning of pollutants will help elucidate the initial sites of toxicity in the organism and aid in the development of realistic allowable levels of these compounds in the environment.
TL;DR: In this paper, an investigation of the marine fouling diatom communities on both nontoxic and toxic test panels suspended from a raft in Langstone Harbor, South Coast of England was conducted.
Abstract: Publisher Summary This chapter discusses an investigation of the marine fouling diatom communities on both nontoxic and toxic test panels suspended from a raft in Langstone Harbor, South Coast of England. A general comparison is made between the floristic composition of these two surface types, which is related to aspects such as the quality and quantity of incorporated antifouling biocide and various environmental parameters, such as depth of immersion of the panels and water temperature. The formation of a primary film and biofouling layers on a surface is influenced by a number of factors including sea–water chemistry, turbulence, temperature, light, and incorporated antifouling biocides. Several reports have drawn attention to the effect of depth on the development of benthic diatom communities. Amphora was by far the most abundant genus within the biofouling layer, other prominent genera being Navicula , Cocconeis , and Synedra . The diversity index method allowed comparison of diatom communities from month to month and it was evident that Amphora coffeaeformis var. perpusilla was the dominant diatom species in most samples.
TL;DR: In this article, electron spin resonance and infrared spectrometries and chlorine analysis were used to obtain information on the occurring interaction mechanisms and type of bonding between humic polymers and Xenobiotic molecules.
Abstract: Product of interaction obtained in aoueous medium between 3 humic acids of synthetic, peat and coal origin and 9 chlorophenoxyalkanoic acids and esters of different chemical structure and and properties (type of alkanoic chain and number of chlorine ring-atoms) were investigated by electron spin resonance and infrared spectrometries and chlorine analysis in order to obtain information on the occurring interaction mechanisms and type of bonding. The increased chlorine content and decreased free radical concentration generally measured in the interaction products, in comparison with values of the original humic acids, confirmed the already suggested incorporation of xenobiotic units by stable covalent bonds into humic polymers, through cross-coupling, homolytic reactions between indigenous humic free radicals and chtorophenoxy-radical intermediates generated by a previous chemical, photochemical and/or enzymatic degradation of the original xenobiotic molecule. For comparative purposes, the study was also extended to the products obtained by interaction of the same chlorophenoxy compounds with 7 more humic acids of different sources, including soil and compost. The various humic acids considered showed a definite, different interacting power in coupling with the xenobiotics, in the order: synthetic > peat> soil> coal>compost. The reactivity of humic acids was found to be indirectly correlated with their carboxyl content and carboxyl/phenolic hydroxyl ratio. The different molecular structure of chlorophenoxyalkanoic compounds did not apparently influence their reactivity towards humic acids. An approximate trend was shown as a function of the number of chlorine ring-atoms, which appeared to affect the reactivity according to the order: monochlorinated > dichlorinated > trichlorinated.
TL;DR: In this article, the authors found that cattle from farms near a coal combustion thermoelectric plant had complete attrition of incisors at 6 to 7 years and the degree of wear was related to the distance between farms and the plant as a linear function.
Abstract: Dental lesions in cattle were studied in 11 farms located within 1.2 to 9.6 km from a coal combustion thermoelectric plant. Incisor teeth of some cattle showed evidence of chronic fluoride poisoning. The most important alteration was dental attrition. Cattle from farms near the plant had complete attrition of incisors at 6 to 7 years. The degree of wear was related to the distance between the farms and the plant as a linear function y = 4.11 + (-0.42x); r 2 = 0.75 (P
TL;DR: The results suggest that renal fluoride clearance decreased not only with the evidence of kidney disease but also with advancing age, which may be an important factor to be considered in the health care of workers exposed to fluoride and of populations living in fluoride polluted areas.
Abstract: Several characteristics of the aging process related to renal function and fluoride metabolism were investigated. A cross-sectional analysis of 1088 healthy subjects by 10-year age groups showed a progressive linear decline in creatinine clearance (CCr) and fluoride clearance (CF). There was a significant reduction in CCr and CF after age 80. The amount of fluoride filtered through the glomeruli per minute (FF), tubular reabsorp-tion of fluoride (TRF) and its rate (%TRF), seemed to remain stable until age 79. The 24-hour excretion of fluoride and CF were well correlated with each other (r=0.83) in 7 patients with chronic renal failure (CRF) and 11 healthy subjects after fluoride administration. The results suggest that renal fluoride clearance decreased not only with the evidence of kidney disease but also with advancing age. For the health care of workers exposed to fluoride and of populations living in fluoride polluted areas, age may be an important factor to be considered.
TL;DR: It is suggested that water movement is an important mechanism which acts to increase the bio-availability of nutrients and therefore allows these algae to achieve high rates of growth even though ambient substrate concentrations are low.
Abstract: Periphyton growth in oligotrophic Lake Tahoe appears to be regulated by nutrient Input and provides additional evidence of cultural eutrophication. A stalked diatom community, Gomphoneis herculeana , dominates the biomass in the eulittoral (splash) zone, and it is the luxuriant growth of this alga which has caused algal biofouling problems in this pristine lake. 15N-labelled nitrate and ammonium uptake experiments showed that this community had a greater affinity for these nutrients than did the sublittoral periphyton community which depended on nitrogen fixation to meet its cellular demands. The rates of nitrogen uptake at natural substrate levels, measured under no flow (static) conditions were too low to account for this community's N-demand. We suggest that water movement (e.g., wave action) is an important mechanism which acts to increase the bio-availability of nutrients and therefore allows these algae to achieve high rates of growth even though ambient substrate concentrations are low.
TL;DR: In this article, strong-base ion exchange fibrous materials (SBF) were used as sorbents for purification of air from acid impurities exemplified by SO 2, and the results of the investigation of their physico-chemical and mechanical properties, chemical stability, as well as the data on water and sulphur dioxide sorption as a function of their concentration in the gas phase.
Abstract: Strong-base ion-exchange fibrous materials (SBF) were tested as sorbents for purification of air from acid impurities exemplified by SO 2 . The SBF exchangers were prepared by amination with the trimethylamine of chloromethylated polystyrene grafted on polypropylene fibres. In the present paper are presented the results of the investigation of their physico-chemical and mechanical properties, chemical stability, as well as the data on water and sulphur dioxide sorption as a function of their concentration in the gas phase. Influence of different parameters on the efficiency of absorption of SO 2 from air by CO 3 2- and HCO 3 − forms of the fibres has been tested. These parameters are: gas flow rate, concentration, and air humidity. The optimal condition for regeneration has been established. It has been shown that the fibrous ion-exchange materials made of strong-base fibres are highly efficient means for removal of SO 2 from air.
TL;DR: 1-DGA is a fungicide with cationic surface active properties, which has been used particularly against scab of apple and pear since its introduction in 1956.
Abstract: Publisher Summary This chapter elaborates the synergism among antifouling biocides. The results of an investigation into the effects of tributyltinoxide (TBTO), together with two cationic surfactants, 1-dodecylguanidineacetate (1-guanidinododecaneacetate; trade names dodine, cyprex, melprex) or 2-dodecylguanidine acetate (2-guanidinododecane acetate; guanidine, (1-methylundecyl)-monoacetate) on the diatom Amphora coffeaeformis are reported in the chapter. TBTO exhibits pronounced algicidal activity against the diatom A. coffeaeformis and a total kill is achieved at a concentration of 250 nM. 1-DGA is a fungicide with cationic surface active properties, which has been used particularly against scab of apple and pear since its introduction in 1956. There are many examples of synergism between biocides and this has been used to enhance the action of drugs, antibiotics, and fungicides.
TL;DR: In this article, the physic-chemical processes affecting copper, zinc, and tin toxicity to algae were studied and the relative importance of these interactions (both magnitude and time dependence) were discussed.
Abstract: Publisher Summary This chapter focuses on the physic-chemical processes affecting copper, zinc, and tin toxicity to algae. Both Cu and Zn are essential algal micronutrients, cofactors in numerous biochemical processes. The availability of a nutrient or toxic substance can be significantly affected by precipitation. Methods for modeling the effects of adsorption–desorption reactions have been previously reviewed. Useful predictions of algal response require an understanding of the relative importance of these interactions (both magnitude and time dependence). Photoreduction and dissolution of Mn oxides by dissolved humic substances has been proposed as an important factor regulating dissolved Mn distribution in seawater. Photodegradation of iron (Fe) chelates also enhances Fe uptake by algae. Anderson et al. observed that Fe uptake by Thalassiosira weissflogii in a chemically defined medium dominated by FeEDTA complexation doubled in the presence of light.
TL;DR: Sulphur dioxide emissions reached all-time highs around 1970 to 1973 and SO2 emissions in both countries decreased from that time until the early 1980's as discussed by the authors, and Canadian emissions decreased from 6.6 to 3.8 million tonnes in the same time period.
Abstract: Studies of environmental damage from acidification by acid deposition in Canada date from the 1950's. in the late 1960's, acidification of surface waters and other forms of environmental damage near point source emissions in Canada and the United States led to development of Clean Air Acts in both countries and the implementation of various control programs. Sulphur dioxide emissions reached all-time highs around 1970 to 1973 and SO2 emissions in both countries decreased from that time until the early 1980's. U.S. emissions decreased from about 28 million tonnes to 21 million tonnes from 1973 to 1984 and Canadian emissions decreased from 6.6 to 3.8 million tonnes in the same time period. Canadian emissions are ensured to decrease further as a result of Canada's Sulphur Dioxide Control Program which goes beyond the objectives of the 30% Club.
The aquatic environment has responded favorably to these emission reductions. Sulphate runoff from 12 Nova Scotian and 8 Newfoundland watersheds decreased by nearly 50% in the corresponding time. Rivers in both cases showed an expected increase in pH. Near Sudbury, Ontario, following reductions in emissions from the large smelters, surface water sulphate concentrations have declined and pH of the acidified lakes has increased.
The past reductions in SO2 and favorable response in the environment is most encouraging but we are still faced with a situation of extensive surface water damage. Lakes in large areas of Eastern Canada have less than 20% of the alkalinity expected from normal weathering processes and as many as 14,000 individual lakes have been acidified. There are examples of the top meter of soil water being acidified by a combination of sulphate and nitrate.
Biological surveys have documented a continuing decline in biological quality of lakes and have documented the loss of aquatic organisms as a result of periodic pH depressions in streams.
In recent years, we have observed decline of sugar maple, our national emblem, in Central and Eastern Canada. the trees have been subjected to attacks by tent caterpillar and severe weather conditions. There is increasing evidence that the decline is caused by a complex interaction of insect damage, weather and stress caused by acidic precipitation.
We can conclude from the eastern North American experience that while emissions and deposition have been reduced and water quality has improved, both the aquatic and forest situations are still far from acceptable.
TL;DR: Although amino acids do not themselves represent a health hazard, they can be transformed to hazardous substances during subsequent treatment or they may constitute an organic residual easily assimiliable in the poster supply, so it is necessary to minimize this release.
Abstract: The α-amino acids, essential cellular constituents, come from protein degradation, metabolites or industrial wastes and are present in fresh water. Their total concentration in the free state varies from 0.02 to 0.3 mg NI −I These compounds may be analysed by HPLC and fluorescence detection after orthophtaldialdehyde derivatization. A concentration step on a cation exchange resin must first be performed. In the initial phase of our study, we followed the concentration of amino acids through the different steps of a drinking-water treatment plant. An increasing concentration of amino acids often appeared after sand filtration. In order to examine this phenomenon, we conducted a study with a pilot scale — aerated carbon biological filter. During this study, a release of free amino acids, proteins, or peptides was noticed. This release may result from an “in situ” cellular lysis or it may merely reflect the presence of cellular metabollites. Nevertheless, the release of amino acids is reduced when the filter media is activated carbon, which adsorbs the aromatic amino acids. Although amino acids do not themselves represent a health hazard, they can be transformed to hazardous substances during subsequent treatment or they may constitute an organic residual easily assimiliable in the poster supply. Thus, it is necessary to minimize this release.