Efeitos do cobre na macrófita potamogeton pectinatus L. e sua possível utilização o monitoramento ou remediação de ambientes aquáticos contaminados por este metal

O cobre é um metal essencial para as plantas, porém considerado tóxico quando em elevadas concentrações na água. No caso de macrófitas aquáticas já foi demonstrado que este metal inibe o processo fotossintético e provoca alterações pigmentares. Neste contexto, expusemos (96h) a macrófita aquática Potamogeton pectinatus (L.) à diferentes concentrações de cobre 1, 10, 100 e 1000 µM para avaliar o potencial bioacumulador da planta, e às concentrações de 1, 10 e 100 µM de Cu para verificar os possíveis efeitos do metal na taxa fotossintética (24 e 96h) em diferentes intensidades luminosas (17, 100, 300 e 500 µmol/m2 /s), no teor pigmentar (96h) e no crescimento das macrófitas (30 dias). Para os experimentos de bioacumulação mantivemos um grupo de plantas controle (sem adição de cobre no meio), enquanto que para os outros testes mantivemos um grupo controle e um grupo em solução nutritiva de Hoagland 100%, que contem cobre e outros micronutrientes em concentrações ideais para sobrevivência e crescimento de P. pectinatus. Nossos resultados mostram que a macrófita P. pectinatus é capaz de acumular altas concentrações de cobre, sendo que este acúmulo aumenta com a elevação dos níveis do metal na água. Apesar de basicamente não haver diferença estatística entre a concentração do metal nos diferentes órgãos da planta, as raízes mostraram-se capazes de acumular mais cobre que as folhas e caule com base no fator de bioconcentração. Com relação aos teores de clorofila “a”, “b” e carotenoides, estes foram menores nas folhas das plantas controle em comparação com as plantas em solução de Hogland, mas esta diferença só foi significativa nas plantas expostas ao cobre, que apresentaram menor concentração dos teores pigmentares já à 1 µM de Cu. Quanto à fotossíntese, em 24h de exposição, novamente observamos um efeito negativo da ausência e presença de cobre nas concentrações de 1, 10 e 100 µM, bem como, um efeito da luminosidade, de forma que as plantas em solução de Hoagland apresentaram maior taxa fotossintética quando em 100 µmol/m2 /s. Em virtude de um aumento na respiração em 96h, a fotossíntese, quando ocorreu, foi menor que em 24h e não diferiu entre os grupos e luminosidade. Em relação ao crescimento, as plantas perderam biomassa, mas mantiveram seus comprimentos e apenas aquelas em solução de Hoagland aumentaram seu número de folhas. Ainda, verificou-se clorose e necrose nas plantas controle e expostas ao cobre. Diante do exposto, concluímos que a macrófita P. pectinatus acumula altas concentrações de cobre, principalmente na raiz, sendo capaz e refletir as concentrações do metal no meio. Esta condição, sugere seu uso no biomonitoramento e fitorremediação de locais contaminados por cobre. Por outro lado, elas mostram-se sensíveis ao metal pela redução no teor pigmentar e fotossíntese, sugerindo estes como mecanismos toxicidade do cobre.

Environmental effects of thermal and radioactive discharges from nuclear power plants in the boreal brackish-water conditions of the northern Baltic Sea

During recent decades, thermal and radioactive discharges from nuclear power plants into the aquatic environment have become the subject of lively debate as an ecological concern. The target of this thesis was to summarize the large quantity of results obtained in extensive monitoring programmes and studies carried out in recipient sea areas off the Finnish nuclear power plants at Loviisa and Olkiluoto during more than four decades. The Loviisa NPP is located on the coast of the Gulf of Finland and Olkiluoto NPP on that of the Bothnian Sea. The state of the Gulf of Finland is clearly more eutrophic; the nutrient concentrations in the surface water are about 1½ 2 times higher at Loviisa than at Olkiluoto, and the total phosphorus concentrations still increased in both areas (even doubled at Loviisa) between the early 1970s and 2000. Thus, it is a challenge to distinguish the local effects of thermal discharges from the general eutrophication process of the Gulf of Finland. The salinity is generally low in the brackish-water conditions of the northern Baltic Sea, being however about 1 higher at Olkiluoto than at Loviisa (the salinity of surface water varying at the latter from near to 0 in early spring to 4 6 in late autumn). Thus, many marine and fresh-water organisms live in the Loviisa area close to their limit of existence, which makes the biota sensitive to any additional stress. The characteristics of the discharge areas of the two sites differ from each other in many respects: the discharge area at Loviisa is a semi-enclosed bay in the inner archipelago, where the exchange of water is limited, while the discharge area at Olkiluoto is more open, and the exchange of water with the open Bothnian Sea is more effective. The effects of the cooling water discharged from the power plants on the temperatures in the sea were most obvious in winter. The formation of a permanent ice cover in the discharge areas has been delayed in early winter, and the break-up of the ice occurs earlier in spring. The prolonging of the growing season and the disturbance of the overwintering time, in conditions where the biota has adjusted to a distinct rest period in winter, have been the most significant biological effects of the thermal pollution. The soft-bottom macrofauna at Loviisa has deteriorated to the point of almost total extinction at many sampling stations during the past 40 years. A similar decline has been reported for the whole eastern Gulf of Finland. However, the local eutrophication process seems to have contributed into the decline of the zoobenthos in the discharge area at Loviisa. Thermal discharges have increased the production of organic matter, which again has led to more organic bottom deposits. These have in turn increased the tendency of the isolated deeps to a depletion of oxygen, and this has further caused strong remobilization of phosphorus from the bottom sediments. Phytoplankton primary production and primary production capacity doubled in the whole area between the late 1960s and the late 1990s, but started to decrease a little at the beginning of this century. The focus of the production shifted from spring to mid- and late summer. The general rise in the level of primary production was mainly due to the increase in nutrient concentrations over the whole Gulf of Finland, but the thermal discharge contributed to a stronger increase of production in the discharge area compared to that in the intake area. The eutrophication of littoral vegetation in the discharge area has been the most obvious, unambiguous and significant biological effect of the heated water. Myriophyllum spicatum, Potamogeton perfoliatus and Potamogeton pectinatus, and vigorous growths of numerous filamentous algae as their epiphytes have strongly increased in the vicinity of the cooling water outlet, where they have formed dense populations in the littoral zone in late summer. However, the strongest increase of phytobenthos has extended only to a distance of about 1 km from the outlet, i.e., the changes in vegetation have been largest in those areas that remain ice-free in winter. Similar trends were also discernible at Olkiluoto, but to a clearly smaller extent, which was due to the definitely weaker level of background eutrophy and nutrient concentrations in the Bothnian Sea, and the differing local hydrographical and biological factors prevailing in the Olkiluoto area. The level of primary production has also increased at Olkiluoto, but has remained at a clearly lower level than at Loviisa. In spite of the analogous changes observed in the macrozoobenthos, the benthic fauna has remained strong and diversified in the Olkiluoto area. Small amounts of local discharge nuclides were regularly detected in environmental samples taken from the discharge areas: tritium in seawater samples, and activation products, such as 60Co, 58Co, 54Mn, 110mAg, 51Cr, in suspended particulate matter, bottom sediments and in several indicator organisms (e.g., periphyton and Fucus vesiculosus) that effectively accumulate radioactive substances from the medium. The tritium discharges and the consequent detection frequency and concentrations of tritium in seawater were higher at Loviisa, but the concentrations of the activation products were higher at Olkiluoto, where traces of local discharge nuclides were also observed over a clearly wider area, due to the better exchange of water than at Loviisa, where local discharge nuclides were only detected outside Hästholmsfjärden Bay quite rarely and in smaller amounts. At the farthest, an insignificant trace amount (0.2 Bq kg-1 d.w.) of 60Co originating from Olkiluoto was detected in Fucus at a distance of 137 km from the power plant. Discharge nuclides from the local nuclear power plants were almost exclusively detected at the lower trophic levels of the ecosystems. Traces of local discharge nuclides were very seldom detected in fish, and even then only in very low quantities. As a consequence of the reduced discharges, the concentrations of local discharge nuclides in the environment have decreased noticeably in recent years at both Loviisa and Olkiluoto. Although the concentrations in environmental samples, and above all, the discharge data, are presented as seemingly large numbers, the radiation doses caused by them to the population and to the biota are very low, practically insignificant. The effects of the thermal discharges have been more significant, at least to the wildlife in the discharge areas of the cooling water, although the area of impact has been relatively small. The results show that the nutrient level and the exchange of water in the discharge area of a nuclear power plant are of crucial importance.

The Impact of Endothall on the Aquatic Plant Community of Kress Lake, Washington

CA dense mat-forming population of Eurasian watermilfoil ( Myriophyllum spicatum L . ) was interfering with fishing and recreation in a small western Washington lake. A low concentration (1.5 mg/L active ingredient) of the herbicide endothall formulated as Aquathol® K was used in 2000 to attempt to selectively control the Eurasian watermilfoil. Aquatic plant biomass and frequency data were collected before treatment, ten weeks after treatment and during the growing season for 3 additional years. Macrophyte data were analyzed to assess the herbicide’s impacts on Eurasian watermilfoil as well as the rest of the aquatic plant community. Results showed a significant decrease in Eurasian watermilfoil biomass and frequency 10 weeks after treatment. The Eurasian watermilfoil continued to be present, but at a significantly reduced level through the remainder of the study (3 years after treatment). Of the native plant species, large-leaf pondweed ( Potamogeton amplifolius Tucker . ) frequency and biomass was significantly reduced after treatment. Common elodea ( Elodea canadensis Rich.), muskgrass ( Chara sp. Vallaint.) and bladderwort ( Utricularia sp. L.) all increased significantly after treatment. (PDF has 6 pages.)

Influence of Dilute Acetic Acid Treatments on American Pondweed Winter Buds in the Nevada Irrigation District, California

American pondweed ( Potamogeton nodosus Poir.) is commonly found in northern California irrigation canals. The purpose of this study was to test the hypothesis that exposure of American pondweed winter buds to dilute acetic acid under field conditions would result in reduced subsequent biomass.

Interactions between American pondweed and monoecious hydrilla grown in mixtures

To assess the potential for monoecious hydrilla ( Hydrilla verticillata (L.f.) Royle) to invade existing aquatic plant communities, monoecious hydrilla was grown in mixtures with American pondweed ( Potamogeton nodosus Poiret). When grown with hydrilla from axillary turions, American pondweed was a stronger competitor. When grown with hydrilla from tubers, American pondweed was equally as strong a competitor as hydrilla.

Macrophyte - mollusc relationship in Lake Kariba

Five species of submerged vegetation Lagarosiphon ilicifolius, Najas pectinata, Vallisneria aethiopica, Ceratophyllum demersum and Potamogeton octandrus; 7 species of gastropods Melanoides tuberculata, Bellamya capillata, Biomphalaria pfeifferi, Bullinus tropicus, Cleopatra sp, and Lymnaea natalensis and 4 species of bivalves Corbicula africana, Caelatura mossambicensis, Mutela dubia and Aspatharia wahlbergii are correlated with environmental variables particularly slope and transparency, in Lake Kariba. A stepwise regression analysis further revealed interdependence between (Cleopatra sp., B. pfeifferi, L. natalensis, B. capillata, and V. aethiopica as well as between as between C. mossambicensis and L. ilicifolius and N. pectinata. The dependence of B. pfeifferi, L. natalensis, B. capillata, Cleopatra sp. on V. aethiopica and C. mossambicensis on L. ilicifolius and N. pectinata implies that a change in the biomass of the vegetation species may affect distribution and biomass of the faunal species.

马来眼子菜化感作用对斜生栅藻同工酶的影响

采用聚丙烯酰胺凝胶电泳的方法,研究了马来眼子菜(Potamogeton malaianus)和斜生栅藻(Scenedesmusobliquus)共培养系统中斜生栅藻的过氧化物酶(POD)、超歧化物氧化酶(SOD)、过氧化氢酶(CAT)、细胞色素氧化酶(COD)等同工酶的变化,探讨了沉水植物化感作用对藻类部分酶类的影响。与正常生长状态的对照组相比,马来眼子菜作用下的样品组斜生栅藻POD酶带总数保持稳定,但酶谱组成发生变化;样品组斜生栅藻SOD酶带数量减少而CAT酶带数量增加。综合结果表明,样品组藻体在化感作

武汉莲花湖水生植被重建的实践与启示

通过截污、控制养鱼、控藻和科学种植等措施,2~3年内,在长江中游地区水质为劣Ⅴ类的重富营养湖泊武汉小莲花湖重建了以伊乐藻(Elodea nuttallii)为优势种的沉水植物先锋群落,2004和2005年春季的沉水植被盖度分别达到98%和95%,抑制了水华的发生,改善了水质。利用冬季水位低、透明度相对高的时机种植伊乐藻、菹草(Potamogeton crispu)等这些适合冬春季生长的沉水植物是建立沉水植物先锋群落的一个有效途径。由于以伊乐藻或菹草为优势种的先锋群落不稳定,必须配备丰富物种、优化结构、增加

富营养底质对沉水植物的胁迫研究 Ι.乙酸对伊乐藻和菹草萌发与幼芽生长的影响

湖泊底质中有机物的厌氧代谢产生多种有机酸,其中主要成分是乙酸。研究了暴露于不同浓度的乙酸溶液后伊乐藻(Elodea nuttallii)和菹草(Potam ogeton crispus)无性繁殖体的萌发和幼芽的生长状况。1 mmol/L的乙酸能显著抑制伊乐藻幼芽的生长(p<0.05),但对其繁殖体的萌发无明显影响。在4 mmol/L的乙酸影响下,菹草幼芽仍有明显的生长;菹草繁殖体的萌发受到显著抑制(p<0.05),但在随后的培养中可全部萌发。4 mmol/L以上的乙酸暴露3 d或6 d导致伊乐藻全部死亡,

保安湖沉水植物分布的GIS模拟

以 GPS为辅助 ,在保安湖主体湖和桥墩湖进行沉水植物调查。将野外调查数据构建 GIS数据库 ,基于 GIS软件平台 ,运用 Kringing插值法对保安湖沉水植物分布进行模拟。模拟结果清楚地显示出调查时保安湖沉水植物及 4优势种 (金鱼藻 Ceratophyllum demersum L.、穗状狐尾藻 Myriophyllum spicatum L .、微齿眼子菜 Potamogeton maackianus A.Benn.及苦草 Vallisneria spiralis L.)分别在湖中的分布情况。统

Reducing organic substances from anaerobic decomposition of hydrophytes

Oxidation-reduction properties of surface sediments are tightly associated with the geochemistry of substances, and reducing organic substances (ROS) from hydrophytes residues may play an important role in these processes. In this study, composition, dynamics, and properties of ROS from anaerobic decomposition of Eichhornia crassipes (Mart.) Solms, Potamogenton crispus Linn, Vallisneria natans (Lour.) Hara, Lemna trisulca Linn and Microcystis flos-aquae (Wittr) Kirch were investigated using differential pulse voltammetry (DPV). The type of hydrophytes determined both the reducibility and composition of ROS. At the peak time of ROS production, the anaerobic decomposition of M. flos-aquae produced 6 types of ROS, among which 3 belonged to strongly reducing organic substance (SROS), whereas there were only 3-4 types of ROS from the other hydrophytes, 2 of them exhibiting strong reducibility. The order of potential of hydrophytes to produce ROS was estimated to be: M. flos-aquae > E. crassipes > L. trisulca > P. crispus approximate to V. natans, based on the summation of SROS and weakly reducing organic substances (WROS). The dynamic pattern of SROS production was greatly different from WROS. The total SROS appeared periodic fluctuation with reducibility gradually weakening with incubation time, whereas the total WROS increased with incubation time. Reducibility of ROS from hydrophytes was readily affected by acid, base and ligands, suggesting that their properties were related to these aspects. In addition to the reducibility, we believe that more attention should be paid to the other behaviors of ROS in surface sediments.

The accumulation of alkylphenols in submersed plants in spring in urban lake, China

The concentrations of alkylphenols (APs) were investigated in water, sediments and submersed macrophytes from the Moon Lake, Wuhan city, China. The water samples contained APs, ranging up to 26.4 mu g l(-1) for nonylphenol (NP) and 0.68 mu g l(-1) for octylphenol (OP). APs were found in the sediment samples with concentrations ranging from 4.08 to 14.8 for NP and from 0.22 to 1.25 mu g l(-1) dry weight for OP. The samples from the site near former sewage inlet showed the highest concentrations of APs in both water and sediments. The results of distribution pattern and dynamics of NP and OP in submersed macrophytes of the Moon Lake showed that the two pollutants were all found in Myriophyllum verticillatum, Elodea nuttallii, Ceratophyllum oryzetorum, and Potamageton crispus collected from the Moon Lake. For NP, M. verticillatum had the highest capacity of accumulation, followed by E. nuttallii, C. oryzetorum and P. crispus. However the distribution pattern of OP differed from that of NP, and the highest amount of accumulation was observed in E. nuttallii, followed by M. verticillatum, P. crispus, and C. oryzetorum. The temporal pattern of APs was also observed in submersed macrophytes from March to May, and the highest accumulation period was in May. (c) 2008 Elsevier Ltd. All rights reserved.

Allelopathic interactions between Potamogelon maackianus and Microcystis aeruginosa

The allelopathic interactions between Potamogeton maackianus and toxic cyanobacteria (Microcystis aeruginosa) were studied. P maackianus inhibited the growth of M. aeruginosa, both in a coexistence culture system and in exudates experimental culture system. M. aeruginosa also showed effects on the secondary metabolic biosynthesis and secreting behavior of P maackianus. The main lipophilic components of the hexane extracts and the exudates from the macrophyte were analyzed through GC-MS determination. The lipophilic components of the hexane extracts and the exudates from P. maackianus were influenced by M. aeruginosa or their released chemicals. Comparing the lipophilic constituents of the hexane extracts with those in the exudates, the results showed that weak polar compounds contained in the macrophytes can be secreted into the surrounding water. Many compounds, such as N-phenyl-2-naphthalenamine and isopropyl myristate, were detected both in the hexane extracts and the exudates. The changes of lipophilic components in the hexane extracts would be a response to the stress of toxic cyanobacteria or their released toxins. Those changes of exudates, especially the increased content of N-phenyl-2-naphthalenamine, might also be an induced defensive behavior mediated by the released toxins from M aeruginosa. The study results about reciprocal allelopathic responses between macrophytes and cyanobacteria can help in the management of eutrophic waters, and is also important information concerning strategies for recovering eutrophic waters.