Fertilizers and eutrophication in southwestern Australia: Setting the scene

An excess of plant nutrients has caused serious eutrophication in aquatic ecosystems of southwestern Australia manifested by excessive growth and accumulation of green and bluegreen algae. Phosphorus is generally the limiting nutrient for algal growth and phosphatic fertilizers applied to nutrient-deficient, leaching, sandy soils are the main source of P, supplemented by rural industry point sources. Nitrogen is the limiting nutrient in marine embayments with little drainage from the land. Measures to reduce the load of P delivered to drainage include basing fertilizer application rates on soil testing for P and the use of less soluble P fertilizers. Catchment management plans are being implemented with community involvement to reduce P loads and maintain agricultural production. This introductory paper reviews the history of eutrophication in southwestern Australia and of studies into its causes, principally in the large Peel-Harvey estuary. It briefly summarises other papers in this special issue concerned with different aspects of the problem: how to fertilize the land without causing eutrophication.     

大沙河水库富营养化及蓝藻水华特点分析

依据近几年来大沙河水库水质监测和水生态调查的成果资料,通过对大沙河水库水质现状,富营养化程度和蓝藻水华特点的分析评价,总结了大沙河水库蓝藻水华呈现持续爆发,偶尔消退的特点。进一步评估了水华发生风险,分析了水库污染的原因,提出了保护和治理建议。     

水环境中蓝藻毒素研究进展

随着社会的发展,水体富营养化日益严重,藻类及藻毒素严重污染了水环境,不仅给传统净水工艺带来不利影响,增加了水处理难度,而且严重威胁人类健康和生命安全,已成为全球性的环境问题.本文较详细地介绍了蓝藻的起源、特性及其危害,并综述了有关其检测方法及防治措施.最后,对蓝藻毒素降解技术的发展方向进行展望.     

去除藻毒素的水处理方法

蓝-绿藻水华及其所含毒素已成为我国许多富营养化水源的主要问题.蓝-绿藻所含的毒素是复杂的有机化合物,其中包括神经毒素、肝毒素和皮肤毒素.在水处理时如能有效去除藻类,则藻毒素将随之减少.除藻措施可在水源地或水厂内同时进行.在水源处可采取的措施是预氧化、投加除藻剂和防止水源水因水质或水温而引起的上下分层.一般水厂常规处理工艺不能有效去除藻毒素,可以采用强化混凝、优化粉末活性炭和臭氧以及氯的投加量、用生物活性炭过滤或组合工艺.其中生物预处理、臭氧氧化、粉末或颗粒活性炭吸附有较好去除效果.但是在藻类大量繁殖时,须慎重采用预氧化,否则当用氯或臭氧进行预氧化时,如投药量不当,会使藻细胞破裂,反而析出较多的毒素到水中.蓝-绿藻毒素的最佳去除工艺是臭氧和活性炭相结合的生物活性炭法.     

Overview of the potent cyanobacterial neurotoxin β-methylamino-L-alanine (BMAA) and its analytical determination

Blue-green algae are responsible for the production of different types of toxins which can be neurotoxic, hepatotoxic, cytotoxic and dermatotoxic and that can affect both aquatic and terrestrial life. Since its discovery the neurotoxin β-methylamino-L-alanine (BMAA) has been a cause for concern, being associated with the neurodegenerative disease amyotrophic lateral sclerosis/Parkinsonism–dementia complex (ALS/PDC). The initial focus was on Guam where it was observed that a high number of people were affected by the ALS/PDC complex. Subsequently, researchers were surprised to find levels of BMAA in post mortem brains from Canadian patients who also suffered from ALS/PDC. Recent research demonstrates that BMAA has been found at different levels in the aquatic food web in the brackish waters of the Baltic Sea. There is emerging evidence to suggest that sand-borne algae from Qatar can also contain BMAA. Furthermore, there is now concern because BMAA has been found not only in warmer regions of the world but also in temperate regions like Europe. The aim of this review is to focus on the methods of extraction and analysis of the neurotoxic non-protein amino acid BMAA. We also consider the neurotoxicity, aetiology, and diverse sources and routes of exposure to BMAA. In recent years, different methods have been developed for the analysis of BMAA. Some of these use HPLC-FD, UPLC-UV, UPLC-MS and LC-MS/MS using samples that have been derivatised or underivatised. To date the LC-MS/MS approach is the most widely used analytical technique as it is the most selective and sensitive method for BMAA determination.     

Relevance and challenges in monitoring marine biotoxins in non-bivalve vectors

Seafood poisoning outbreaks can be caused by marine biotoxins which are naturally produced by harmful algal blooms. To minimize the risk of acute intoxications due to consumption of contaminated seafood a proper monitoring program must be in place. In recent decades several directives have been laid down by the European Commission to regulate known toxins, reassess their regulatory limits and update their reference detection methods. However, a revision of the seafood organisms that can act as toxin vectors has not been carried out. The control system has been designed based on physiological specificities of live bivalve mollusks. Although the prescribed controls in EC regulation 854/2004 apply to echinoderms, tunicates and marine gastropods, several difficulties are posed to a cost-effective monitoring program for these quite diverse and non-analogous groups of seafood organisms. Echinoderms, tunicates and marine gastropods are frequently secondary target species for toxins surveillance. In this study, the potential of non-bivalve organisms as toxin vectors and their threat for public health is evaluated based on their feeding behavior (i.e. filter-feeders, herbivores, predators), growth and metabolic rates, motile capacity and dynamics of toxin accumulation/elimination. A summary of previous reports on toxin accumulation and human incidents is presented to highlight the seafood species of higher risk to consumers, including crustaceans that are not listed in the EU directives for toxins monitoring and should be strongly considered as potent vectors of biotoxins to humans. Finally, the challenges in terms of sampling efforts and analytical determination for the regular surveillance of biotoxins in non-bivalve vectors are discussed.     

How Brittany and Florida coasts cope with green tides

Although the direct involvement of nitrogen and phosphorus has been shown, eutrophication remains poorly managed to this day. The excessive growth of some opportunist seaweeds is the consequence in coastal ecosystems close to agricultural or strongly urbanized and industrialized zones. In Brittany, a leading tourist region of France, green tides set down on the beaches big quantities of Ulva, of which some 100,000 m³ are harvested annually, with significant ecological and economic consequences. In Florida, although the macroalgae (notably Codium) drift about with the currents, they are of sufficient mass and spread over such areal extent to inhibit penetration of sunlight through the water column to the coral reef surface. They strand also on the beaches. Stabilization of algae by composting and methanization of hydrolyzed and pressed algae juice are two methods which have been studied in Brittany and can be used to enhance the value of the harvested seaweed, depending on local conditions and on evolution of needs in energy, basic materials or organic products. But the parallel made here between two very different ecosystems, both disturbed, leads above all to the question of what course to follow now to avoid a worldwide disaster.

Bien que le rôle de l’azote et du phosphore dans les processus d’eutrophication ait été montré, celle‐ci reste mal contrôlée à ce jour. La croissance excessive d’algues opportunistes en est la conséquence dans des écosystèmes côtiers proches de zones agricoles ou fortement urbanisées et industrialisées. En Bretagne, région touristique de France, des marées vertes déversent sur les plages de grandes quantités d’ulves, dont environ 100,000 m³ sont récoltés annuellement, avec d’importantes conséquences écologiques et économiques. En Floride, bien que les macroalgues (notamment Codium) dérivent avec les courants, elles sont en masse suffisante et suffisamment réparties pour empêcher la pénétration de la lumière dans la colonne d’eau jusqu’au récif de corail. Elles s’échouent également sur les plages. La stabilisation par compostage et la méthanisation de jus d’algues hydrolysées et pressées sont deux méthodes qui ont été étudiées en Bretagne afin de valoriser l’algue récoltée, en fonction des conditions locales et de l’évolution des besoins en énergie, matières premières ou produits organiques. Mais le parallèle fait ici entre deux écosystèmes très différents, tous deux perturbés, mène surtout à se demander quelle voie suivre maintenant pour éviter un désastre mondial.     

Calmodulin and Its Interactive Proteins Participate in Regulating the Explosive Growth of Alexandrium pacificum (Dinoflagellate)

Alexandrium pacificum is a typical dinoflagellate that can cause harmful algal blooms, resulting in negative impacts on ecology and human health. The calcium (Ca²⁺) signal transduction pathway plays an important role in cell proliferation. Calmodulin (CaM) and CaM-related proteins are the main cellular Ca²⁺ sensors, and can act as an intermediate in the Ca²⁺ signal transduction pathway. In this study, the proteins that interacted with CaM of A. pacificum were screened by two-dimensional electrophoresis analysis and far western blots under different growth conditions including lag phase and high phosphorus and manganese induced log phase (HPM). The interactive proteins were then identified using matrix-assisted laser desorption ionization time-of-flight mass spectrometry. Four proteins were identified, including Ca²⁺/CaM-dependent protein kinase, serine/threonine kinase, annexin, and inositol-3-phosphate synthase, which all showed high expression levels under HPM. The gene expression levels encoding these four proteins were also up-regulated under HPM, as revealed by quantitative polymerase chain reaction, suggesting that the identified proteins participate in the Ca²⁺ transport channel and cell cycle regulation to promote cell division. A network of proteins interacting with CaM and their target proteins involved in the regulation of cell proliferation was raised, which provided new insights into the mechanisms behind the explosive growth of A. pacificum.     

A systematic study on spatial and seasonal patterns of eight taste and odor compounds with relation to various biotic and abiotic parameters in Gonghu Bay of Lake Taihu, China

A systematic study was conducted on seasonal and spatial patterns of taste and odor (T&O) compounds with relation to biotic and abiotic parameters at fifteen sites in Gonghu Bay of Lake Taihu in 2008. We developed a sensitive and automated method to simultaneously analyze eight T&O compounds (boiling points ranging from 38 °C to 239 °C) by using Purge-and-Trap (P&T) coupled with GC/MS. Maximum particulate dimethyl trisulfide (DMTS, 69.6 ng/L) exceeded its odor threshold concentrations (OTC, 10 ng/L) and maximum dissolved DMTS was 6.1 ng/L, but still far below concentration in the drinking water pollution incident of Wuxi City in 2007 when DMTS reached 1768-11,399 ng/L. Geosmin (GEO), 2-methylisoborneol (MIB), β-cyclocitral, β-ionone and 2-isobutyl-3-methoxypyrazine (IBMP) occasionally or frequently exceeded their OTCs, whereas 2-isopropyl-3-methoxypyrazine (IPMP) and dimethyl sulfide (DMS) did not. We found for the first time significant correlations between particulate β-cyclocitral and β-ionon concentrations and intracellular and extracellular microcystin concentrations. Spatially, Nanquan Waterworks faced more risk by T&O contamination than Xidong Waterworks. High concentrations of NO₃-N, TDN and TN could be risky signs of taste and odor events by DMS, DMTS, IPMP, IBMP and GEO.