Mitigation of low stream pH and its effects on salmonids

Crushed limestone (200 tonnes) was spread in bars on the bed of an acidic brook (mean pH 5.0) in Nova Scotia, Canada. A seasonally variable but significant increase in pH of running water resulted, and a longitudinal pH gradient over the limed section extended to the mouth of the brook. The effectiveness persisted after 3 years, during which pH downstream of the limestone increased an average of 0.4 pH units (range < 0.1-1.3 pH units) along with significantly increased Ca, Mg and acid neutralizing capacity. Total and exchangeable Al were not altered by the limestone and non-exchangeable forms dominated. The interstitial water was nearly neutral (mean pH 7.1) in limestone beds but it was acidic (mean pH 5.4) in gravel beds of the control section upstream. Spawning Atlantic salmon (Salmo salar) dug three times more redds in gravel of the limed section than in the control. Salmon fry survived and they were significantly more abundant in the limed section than in the control. The density of juvenile salmon increased over time, indicating a recovery of the population. The density of brook trout (Salvelinus fontinalis) also increased and trout fry were usually more abundant in the limed section than in the control. The observed benefits for salmonids suggest that small-scale application of limestone to stream beds and spawning sites can be used to mitigate the effects of low stream pH.     

The interactive effects of low pH, toxic metals, and DOC on a simulated temporary pond community

The effects of pH, potentially toxic metals, and dissolved organic carbon (DOC) on a freshwater, palustrine wetland assemblage (three amphibian species, one mosquito genus, and 18 genera of algae) were examined in 500 liter outdoor mesocosms. The design was fully factorial and exposure levels were set to represent concentrations that occur naturally in temporary ponds in central Pennsylvania, an acid-impacted region of the USA. Water chemistry was precisely regulated by use of an artificial pond water rather than using stream water or well water with partially unknown composition. Jefferson (Ambystoma jeffersonianum) and spotted salamanders (A. maculatum) were negatively impacted by low pH and high metal concentrations. Wood frogs (Rana sylvatica) were negatively impacted by high DOC and low pH. These negative effects included increased time to metamorphosis and decreased survival and wet body mass at metamorphosis. Mosquito emergence was unaffected by pH, metals, or DOC. All three abiotic factors (metals, pH, and DOC) interacted to determine algal taxonomic composition. Hence, abiotic conditions may determine amphibian reproductive success both directly and indirectly, via effects on algae, since a primary food source of salamanders, zooplankton, are affected by changes in algal composition. These complex interactions should be considered in evaluating the possible toxicity of pond waters to fauna and flora. Until now, pH alone has been considered the primary limiting factor for amphibians breeding in temporary ponds.     

Biochemical responses in Salmo salar muscle following exposure to ethynylestradiol and tributyltin

This study investigated the effects of nominal concentrations of two endocrine-disrupting chemicals (EDCs) on fish physiology. The effects of the synthetic pharmaceutical estrogen ethynylestradiol (EE(2)) and the antifoulant tributyltin (TBT) were investigated in exposure studies with immature Atlantic salmon, Salmo salar. Fish were exposed for 7 days to waterborne EE(2), TBT, or a combination of both. The activities of lactate dehydrogenase (LDH), acetylcholinesterase (AchE) and glutathione S-transferase (GST), and lactate and glycogen content were determined in samples of fish muscle. Fish exposed to EE(2) for 3 days responded rapidly with increasing AchE and GST activities and increasing lactate content. These responses were limited to the first 3 days of exposure and had disappeared by day 7, indicating that the fish had adapted to EE(2) exposure. Compared to the controls, TBT increased AchE and LDH activity, inhibited GST activity and had no effect on lactate content. When mixed, the highest concentration of EE(2) increased the effect of TBT on lactate content. However, fish exposed to a lower concentration of EE(2) in combination with TBT had the lowest lactate content. Effects on AchE and LDH activities were smaller when TBT was combined with EE(2) compared to TBT alone. This suggests that TBT and EE(2) influence biochemical processes in fish muscle, acting on different organizational levels, by antagonistic and synergistic mechanisms.     

Biochemical and locomotor responses of Carcinus maenas exposed to the serotonin reuptake inhibitor fluoxetine

The aim of this study was to assess the effects of the widely used anti-depressant fluoxetine on behaviour (locomotion), moulting, neuromuscular transmission, energy production and anti-oxidant defences’ efficiency of the epibenthic crab Carcinus maenas. Crabs were individually exposed to fluoxetine concentrations for 7 d. Effects on locomotion were assessed at the end of the exposure using an open field test adapted to C. maenas in the present study. Tissue samples were later collected to evaluate fluoxetine effects on physiological functions using the activity of key enzymes and other parameters as biomarkers, namely: N-acetyl-β-glucosaminidase (NAGase) in the epidermis (moulting) and the hepatopancreas; cholinesterases (ChE) in muscle (neuromuscular cholinergic transmission); NADP⁺-dependent isocitrate dehydrogenase (IDH) and lactate dehydrogenease (LDH) in muscle (energy production); glutathione S-transferases (GST) in hepatopancreas (biotransformation and oxidative stress system); glutathione reductase (GR), and glutathione peroxidade (GPx), total glutathione levels (TG) and lipid peroxidation levels in the hepatopancreas (anti-oxidant defences and oxidative damage). Because no information on C. maenas NAGase activity was previously available, its variation during the moult cycle was also investigated. The results showed that locomotion was significantly increased at fluoxetine concentrations equal or above 120 μg L⁻¹, with animals spending more time moving, walking longer distances than controls. Levels of NAGase activity were found to vary in relation to C. maenas moult cycle, but no alterations were observed after exposure to fluoxetine. Significant increases in the activity of ChE, GST and GR enzymes, and the levels of TG were found, with a lowest observed effect concentration (LOEC) of 120 μg L⁻¹. Effects on locomotion were significantly and positively correlated to those induced on ChE activity. The results raise concern when hypothesising conditions of chronic exposure in the wild.     

Effects of low pH alone and combined with copper sulphate on blood parameters of rainbow trout

Copper sulphate (0.2 ppm) has only a slight damaging effect on tissues as indicated by measurements of biochemical and haematological parameters. These effects are significantly increased in the presence of sulphuric acid at pH 6.5.     

Distribution of elements in needles of Pinus massoniana (Lamb.) was uneven and affected by needle age

Macronutrients (P, S, K, Na, Mg, Ca), heavy metals (Fe, Zn, Mn, Cu, Pb, Cr, Ni, Cd) and Al concentrations as well as values of Ca/Al in the tip, middle, base sections and sheaths of current year and previous year needles of Pinus massoniana from Xiqiao Mountain were analyzed and the distribution patterns of those elements were compared. The results indicated that many elements were unevenly distributed among the different components of needles. Possible deficiency of P, K, Ca, Mn and Al toxicity occurred in needles under air pollution. Heavy metals may threaten the health of Masson pine. Needle sheaths were good places to look for particulate pollutants, in this case including Fe, Cu, Zn, Pb, Cr, Cd and Al.     

Biochemical and genotoxic effects in women exposed to pesticides in Southern Ecuador

Environmental Science and Pollution Research - Toxicity refers to the potential of a substance such as a pesticide to cause damage to the structure or functions of an exposed organism. Pesticides...     

Distribution of elements in needles of Pinus massoniana (Lamb.) was uneven and affected by needle age

Macronutrients (P, S, K, Na, Mg, Ca), heavy metals (Fe, Zn, Mn, Cu, Pb, Cr, Ni, Cd,) and Al concentrations as well as values of Ca/Al in the tip, middle and base sections, and sheaths of current year and previous year needles of Pinus massoniana from Xiqiao Mountain were analyzed and the distribution patterns of those elements were compared. The results indicated that many elements were unevenly distributed among the different components of needles. Possible deficiency of P, K, Ca, Mn and Al toxicity occurred in needles under air pollution. Heavy metals may threaten the health of Masson pine. Needle sheaths were good places to look for particulate pollutants, in this case including Fe, Cu, Zn, Pb, Cr, Cd and Al.     

The effects of atmospheric nitrogen deposition and soil chemistry on the nutritional status of Pseudotsuga menziesii, Pinus nigra and Pinus sylvestris

The ammonium content and the base cation content, expressed relative to ammonium, are enhanced in the soil of Dutch forests, due to the extremely high deposition of ammonium to the forest floor. A nation-wide investigation was carried out to establish whether and how these changed nitrogen fluxes in deposition and soil affect the nutritional status of coniferous trees. The chemical composition of needles of Douglas fir, Scots pine and Corsican pine showed a regional trend similar to that of deposition and soil solution. Particularly nutrients, expressed relative to nitrogen, decreased from North to South. Of the macronutrients phosphorus was most often deficient and therefore probably limiting in the Douglas fir stands. Many pine trees suffered from relative magnesium shortages. In all stands, magnesium and, in Douglas stands, also phosphorus contents of the needles were negatively correlated with ammonium and ammonium/cation ratios in deposition. However, in contrast to pine trees, nutrient contents in needles of Douglas fir showed correlation with nitrate rather than with ammonium in the soil solution. Correlation analyses indicate that nitrogen fluxes in the soil, indirectly affect the nutritional status of coniferous trees.     

The individual and combined effects of ozone and simulated acid rain on growth, gas exchange rate and water-use efficiency of Pinus armandi Franch

The seedlings of Pinus armandi Franch. were exposed to ozone (O(3)) at 300 ppb for 8 h a day, 6 days a week, and simulated acid rain of pH 3.0 or 2.3, 6 times a week, alone or in combination, for 14 weeks from 15 June to 20 September 1993. The control seedlings were exposed to charcoal-filtered air and simulated rain of pH 6.8 during the same period. Significant interactive effects of O(3) and simulated acid rain on whole plant net photosynthetic rate were observed, but not on other determined parameters. The exposure of the seedlings to O(3) caused the reductions in the dry weight growth, root dry weight relative to the whole plant dry weight, net photosynthetic rate, transpiration rate in light, water-use efficiency and root respiration activity, and increases in shoot/root ratio, and leaf dry weight relative to the whole plant dry weight without an appearance of acute visible foliar injury, but did not affect the dark respiration rate and transpiration rate in the darkness. The decreased net photosynthetic rate was considered to be the major cause for the growth reduction of the seedlings exposed to O(3). On the other hand, the exposure of the seedlings to simulated acid rain reduced the net photosynthetic rate per unit chlorophyll a + b content, but did not induce the significant change in other determined parameters.     

Biochemical changes in needles of Pinus radiata D. Don trees in relationship to long-term ozone exposure indices

Ambient concentrations of ozone in Europe are high enough to cause negative effects on vegetation. Therefore, many efforts have been made to determine exposure indices and critical levels for protection of vegetation. In this context, the choice of a suitable attribute to determine the pollutant effect is of paramount importance. Until now, much of the work has been done with attributes such as biomass or growth. In the present work correlation factors have been established between biochemical parameters (peroxidase activity, ascorbate and sulfhydryl contents) of Pinus radiata trees and exposure indices of ozone. Our results show that peroxidase cannot be used as an indicator of effects of long-term exposure to ozone but still remains as an excellent indicator of short-term ozone fluctuations in the field. Ascorbate may act as an intermediate indicator responding to both short fluctuations and long-term exposures to ozone. Finally, sulfhydryl may be used as a long-term indicator in relation to the AOT (average over threshold) exposure index. Our results also point to the fact that Pinus radiata may be affected by ozone at AOT values lower than 10 ppm.h as already observed with other tree species.     

Role of plants, mycorrhizae and phytochelators in heavy metal contaminated land remediation

Phytoremediation is a site remediation strategy, which employs plants to remove non-volatile and immisible soil contents. This sustainable and inexpensive process is emerging as a viable alternative to traditional contaminated land remediation methods. To enhance phytoremediation as a viable strategy, fast growing plants with high metal uptake ability and rapid biomass gain are needed. This paper provides a brief review of studies in the area of phytoaccumulation, most of which have been carried out in Europe and the USA. Particular attention is given to the role of phytochelators in making the heavy metals bio-available to the plant and their symbionts in enhancing the uptake of bio-available heavy metals.     

Growth and photosynthetic responses of two pine species (Pinus koraiensis and Pinus rigida) in a polluted industrial region in Korea

We investigated the effects of pollutants on two pine species (Pinus koraiensis and Pinus rigida) in an industrial region in Korea, using a physiological approach. The concentrations of fluorine (F) and chlorine (Cl) in the atmosphere, in precipitation and soil water at the damaged site were all significantly higher than at a control site. Moreover, the concentrations of F, Cl and Mn in pine needles were significantly higher, and essential elements and chlorophyll in needles were significantly lower at the damaged site than at the control site. The photosynthetic capacities, shoot length and survival statistics of needles of the two pines were all significantly reduced at the damaged site compared to the control site, especially P. rigida. Based on our comparison of photosynthetic responses and the concentrations of F, Cl and Mn in needles of the two pine species, P. koraiensis is more resistant to excess Mn in its needles than P. rigida.     

Cadmium adsorption and desorption behaviour on goethite at low equilibrium concentrations: effects of pH and index cations

The transport and bioavailability of cadmium is governed mainly by its adsorption-desorption reactions with minerals such as goethite--a common iron oxide mineral in variable charged and highly weathered tropical soils. Soil factors such as pH, temperature, solution Cd concentration, ionic strength and ageing affect Cd adsorption on goethite. The desorption behaviour of Cd from goethite at low concentrations is not fully understood. This study investigates the adsorption-desorption of Cd at low Cd concentrations (Cd adsorbed on goethite from 20 to 300 microM Cd solutions) in Na and Ca nitrate solutions of 0.03 M nominal ionic strengths. Synthetic goethite prepared by ageing a ferric hydroxide gel at high pH and room temperature was used for Cd adsorption and desorption studies. For desorption experiment 10 successive desorptions were made for the whole range of initial Cd concentrations (20-300 microM) in the presence of 0.01 M Ca(NO3)2 or 0.03 M NaNO3 solutions. Cadmium adsorption was found to be higher in Na+ than Ca2+ probably due to the competition of Ca2+ ions with Cd2+ ions for adsorption sites on the surfaces of goethite. The effect of index cation on Cd adsorption diminished with increase in pH from 5.0 to 6.0. Cadmium desorption decreased with increase in pH from 5.0 to 6.0 in both Na and Ca systems. After 10 successive desorptions with 0.03 M NaNO3 at the lowest initially adsorbed Cd approximately 45%, 20% and 7% of the adsorbed Cd was desorbed at pH 5.0, 5.5 and 6.0, respectively. The corresponding desorptions in the presence of 0.01 M Ca(NO3)2 were 49%, 22% and 8%, respectively. The Freundlich parameter, k, based on each progressive step of desorption at different adsorbed concentration increased with increasing desorption step, which may indicates that a fraction of Cd was resistant to desorption. Low Cd desorbability from goethite may be due to its specific adsorption and/or possibly as a result of Cd entrapment in the cracks or defects in goethite structure.     

Light regime, riboflavin, and pH effects on 2,4-D photodegradation in water

A laboratory study was conducted to determine the effects of light regime, riboflavin, and pH on photodegradation of 2,4-D in aqueous solution. In controlled-environment chamber experiments, riboflavin sensitized 2,4-D photolysis in a concentration-dependent manner under both attenuated UV (-UV) and enhanced UV (+UV) light regimes. The photolysis half-life of 2,4-D in solutions containing 10 mg L-1 riboflavin was 9.7 and 12.5 h when exposed to +UV and -UV, respectively, compared to no photolysis in the absence of riboflavin. In contrast, the extrapolated half-life of 2,4-D in solutions containing 2.5 mg L-1 riboflavin was 46 h under +UV and 72 h under -UV. The rate of 2,4-D photolysis in the presence of riboflavin increased under both light regimes as initial pH of the solution was decreased from 7.5 to 4.5. The half-life of 2,4-D in the presence of 10 mg L-1 riboflavin at pH 4.5 and exposed to +UV was 1.6 h. Lumichrome, a principal photoproduct of riboflavin, did not photosensitize 2,4-D. Concentrations of 2,4-dichlorophenol formed as a result of riboflavin-sensitized 2,4-D photolysis were higher under the -UV than the +UV regime. These results indicate that riboflavin concentration, solution pH, and light regime are interacting factors that may be manipulated to enhance rates of aqueous 2,4-D photolysis.     

Interactive effects of aluminum, phosphorus and mycorrhizae on growth and nutrient uptake of Panicum virgatum L. (Poaceae)

The effects of Al on Panicum virgatum (switchgrass), a widespread perennial grass, were determined in relation to factors which might interact with Al in the soil. Plants were grown for 8 weeks in sand culture and were treated with 3 Al levels (0.5, 2.0, 5.0 mM), 2 P levels (0.065, 0.161 mM), 2 inoculum types (vesicular-arbuscular mycorrhizal (VAM) inoculum or VAM-free soil inoculum) and 2 inoculum sources (a high Al forest in NY or a low Al forest in Ohio) in a factorial design. Plant growth decreased with increasing Al and increased with increasing P, but the Al effect was less at high P than low P. VAM-inoculated plants outgrew non-VAM plants, especially at low and medium Al levels. Total P and Ca uptake decreased with increasing Al concentration, especially at low P levels. VAM inoculation did not result in increased P uptake at any Al level though VAM plants took up significantly more Ca than non-VAM plants at any Al level. VAM plants had lower tissue Al concentrations and took up less Al than non-VAM plants; Al uptake increased with increasing soil Al in non-VAM plants but not in VAM plants. Plants given inoculum from the high Al site had significantly lower tissue Al than plants given the low Al site inoculum, regardless of VAM status. We conclude that the presence of a VAM infection, moderate levels of soil P, and the source of the inoculum can reduce the effects of soluble Al. We discuss potential physiological and edaphic mechanisms by which Al may be immobilized and Ca availability increased in the presence of VAM fungi and other soil microflora.     

Multi-biomarker responses in green mussels exposed to PFCs: effects at molecular,cellular, and physiological levels

Perfluorinated chemicals (PFCs) are extremely persistent and have been found extensively in the environment and wildlife. Oceans are the final sink for many persistent organic pollutants (POPs) including PFCs. However, to date, there has been a lack of studies that investigated the environmental consequences of PFCs on marine organisms. To fill in this gap, environmental toxicity of two dominant PFCs, perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA), was examined in a sentinel species, green mussel Perna viridis, using a series of biomarkers corresponding to different biological levels (molecular, cellular, and physiological). Correlations among these biomarkers were also investigated. The results showed that the tested compounds can induce a series adverse effect at different biological levels, including oxidative stress, DNA damage, membrane instability, suppressed filtration rate, and reduced body weight. Correlation analysis revealed that excess production of reactive oxygen species could be the major toxic pathway. An indirect mode of toxic action was also explored where adverse impacts could be secondary effects of PFC exposure. The joint analysis of biomarkers from multiple biological levels resulted in a comprehensive understanding of how PFC exposure can influence the health of organisms. The correlations of these biomarkers also provided a new perspective of the ecological consequences of PFCs.     

Biochemical responses of the marine mussel Mytilus galloprovincialis to petrochemical environmental contamination along the North-western coast of Portugal

Following the development of urban and industrial centres petrochemical products have become a widespread class of contaminants. The aim of this study was to investigate the effects of petrochemical contamination in wild populations of mussels (Mytilus galloprovincialis) along the NW Atlantic coast of Portugal by applying antioxidant and energetic metabolism parameters as biomarkers. For that, mussels were collected at five sampling sites presenting different petrochemical contamination levels. To evaluate the mussels' antioxidant status, enzymatic activities of catalase, superoxide dismutase, glutathione peroxidase, glutathione reductase, glutathione S-transferases, as well as glutathione redox status were evaluated in gills and digestive glands of mussels collected from the selected sites. Lipid peroxidation was determined in the same tissues to quantify cellular oxidative damage. Furthermore, to investigate how energetic processes may respond to these contaminants, the activity of NADP(+)-dependent isocitrate dehydrogenase was determined in mussels' digestive glands, and octopine dehydrogenase was determined in mussels' posterior adductor muscle. Furthermore, the concentrations of aliphatic hydrocarbons, unresolved complex mixture and polycyclic aromatic hydrocarbons (PAHs) were quantified in mussels' tissue, and abiotic parameters were quantified in water samples collected at each site. Several biomarkers showed statistically significant differences among sampling sites. The redundancy analysis (RDA) used to perform the integrated analysis of the data showed a clear separation of the sampling sites in three different assemblages, which are in agreement with the PAHs levels found in mussels tissues. In addition, the RDA indicated that some of the selected biomarkers may be influenced by abiotic parameters (e.g. salinity, pH, nitrates and ammonia). The approach selected for this study seems to be suitable for monitoring petrochemical contamination.     

Interaction of pH with mercuric chloride toxicity to penaeid prawns from a tropical estuary, East Coast of India: enhanced toxicity at low pH

Toxicity tests were conducted to study the interaction of pH and the response of two size groups of penaeid prawns i.e. Penaeus monodon and Penaeus indicus to different sets of five concentrations of HgCl2 (0.01-0.09 mg l(-1)) under a broad range of pH conditions (5-9). Behavioural responses varied according to test solution concentration and nominated values of pH. Abnormality was detected in the higher concentrations with lower pH in smaller size group of P. monodon. High mortality was observed at higher concentration of test solution with low pH. Irrespective of species and size group LC50 demonstrated similar trend of variation with respect to time period. At pH 9 the threshold limit for 65-75 mm size group of P. monodon and P. indicus was 0.043 and 0.049 mg l(-1) respectively while it was 0.041 and 0.035 mg l(-1) respectively at pH 8; and 0.038 and 0.044 mg l(-1) respectively at pH 7. Relative toxicities were significantly varied except for bigger size groups in the studied pH ranges. The result was pronounced at pH 5 with maximum 1.61 times for inter-hour relative toxicity in contrast to all. At pH below 7 of mercury resulted more toxic compared to high pH range (>7) might be due to acid toxicity itself. At each pH smaller size groups were sensitive while bigger shown tolerant. P. monodon were more sensitive than P. indicus. The toxic order of pH effect was 9<8<7<6<5. Toxicity increased significantly (p>0.01) in acidic medium compared to alkaline.