Policies related to agriculture and environment in the European Community

This paper summarizes recent EC policy relating to agriculture and the environment. The important changes in the reform of the Common Agricultural Policy are outlined and in particular the agri-environmental measures that provide for Member States to aid farmers that take measures to reduce pollution from intensive agriculture and improve the rural environment. The Nitrate Directive, which is the first EC Directive relating to agriculture and the environment, is summarized. Other water directives relevant to agriculture and the aquatic environment as they relate to nutrients (nitrogen and phosphorus) in water are also outlined. The EC Fifth Action Programme on the Environment as it relates to agriculture is also considered. Finally, an attempt is made to assess the likely impact of these policies on agriculture and the aquatic environment.     

尼罗河三角洲早—中全新世气候—环境变化对早期农业发展的影响

对尼罗河三角洲平原东北部一个古埃及文化遗址(Kom El-Khilgan)1.5 m长的沉积物剖面KH1开展14C测年、沉积物粒度和孢粉分析.根据岩性、粒度和测年等结果综合判定:剖面150~100 cm地层为早全新世河流相沉积;100~27 cm地层为早、中全新世(8000—4000 cal a BP)三角洲冲积平原沉积,其中涵盖了古埃及前王朝至古王国时期(6500—4131cal a BP)的人类活动信息;27~0 cm为现代表土层.孢粉分析结果反映了在距今8000~4000 a期间:1)研究区气候由湿润过渡为温和,最后趋于干旱;2)随着气候变干,尼罗河上游水文变化对三角洲环境影响减小,研究区由沼泽湿地逐渐过渡为干草甸环境,更多的土地可以被人类利用;3)常被用来指示农业活动的35μm禾本科、陶器碎片和炭屑的出现并逐渐增加,表明该遗址附近的人类农业活动始于距今6500 a左右,并持续至距今4000 a前后.上述证据表明尼罗河三角洲全新世早—中期湿润向干旱过渡的气候驱动了人类农业活动的开展.本研究为进一步探讨尼罗河三角洲古文明对环境适应性研究提供了科学依据.     

Water use in agriculture in China: importance,challenges, and implications for policy

Irrigation is too important for China to live without. With 75% of grain production of China coming from irrigated land, irrigation plays a major role in food security and poverty alleviation in China, and even in stabilizing the world grain market due to the potential significance of China's gain imports. Yet, water use in China's agriculture faces ever-increasing challenges. These include water shortage, pollution, transferring water out of agriculture, and a surprisingly low water use efficiency. Some possible solutions to these problems can be grouped into two categories: supply-side solutions and demand-side solutions. Demand-side solutions that try to raise water use efficiency are more promising and have higher payoffs on investment. In addition to water pricing reform, comprehensive reform is required to induce farmers to use water efficiently in China.     

The transport of trace substances in the atmosphere and their implications for the general circulation of the stratosphere

Summary Considerations concerning the distribution of artificial radioactive substances in the troposphere point to the occurrence of stratospheric-tropospheric exchange in the region of the discontinuity between the tropical and middle latitude tropopause. Computations of the horizontal flux of ozone in the lower stratosphere and examination of the distribution of the tracer tungsten 185 in the stratosphere suggest that the trace substances are transported northwards from the tropical stratosphere by the action of transient eddy processes in which northward moving parcels of air are sinking and southward moving parcels are rising. The amount of ozone transported varies seasonally and is a maximum in the late winter and spring. The total transport appears sufficient to account for the observed spring build-up of ozone in middle and high latitudes. The eddies invoked are shown to be consistent with the observed countergradient transport of heat in the lower stratosphere, the pattern of stratospheric isentropes and the covariance values found from meridional and vertical velocities. The combined results indicate a new view concerning the mechanics of stratospheric motions as contrasted with the classical ideas of mean meridional motions.

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Zusammenfassung Erwägungen im Hinblick auf die Verteilung künstlicher radio-aktiver Bestandteile in der Troposphäre deuten auf das Auftreten von stratosphärischem-troposphärischem Austausch in der Diskontinuäts-Zone zwischen der tropischen und mittleren Breite in der «Tropopause». Berechnungen des horizontalen Einfliessens des Ozons in der niedrigeren Stratosphäre und Untersuchung der Verteilung des Spurmaterials Wolfram 185 in der Stratosphäre deuten darauf hin, dass die Spuren-Bestandteile nordwärts transportiert werden von der tropischen Stratosphäre durch die Wirkung vorübergehender Wirbel-Prozesse; die Luftmassen, die sich in nördlicher Richtung bewegen, sinken, die in südlicher Bewegung, steigen. Der transportierte Ozon-Gehalt wechselt mit der Jahreszeit, ist maximal spät in Winter und Frühjahr. Der gesamte Transport erscheint genügend, um den beobachteten Frühjahrs-Zuwachs von Ozon in den mittleren und höheren Breitegraden zu rechtfertingen. Die in Betracht kommenden Wirbel scheinen in Übereinstimmung zu sein mit dem beobachtetem Hitze-Transport in der niedrigen Stratosphäre entgegen dem Aufstieg, mit dem üblichen Verlauf der stratosphärischen Isotropen und den Werten, die für die Co-Varianten gefunden wurden von meridionalen und vertikalen Geschwindigkeiten. Die kombinierten Resultate geben einen neuen Einblick in den Mechanismus der strato-sphärischen Strömungen in Kontrast zu den klassischen Ideen einer durchschnittlichen meridionalen Strömung.

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Résumé Des considérations concernant la distribution des substances radio-actives artificielles dans la troposphère indiquent l'occurrence d'un échange strato-sphérique-troposphérique dans la région de discontinuité entre les latitudes tropicales et centrales de la tropopause. Des computations du flux horizontal d'ozone dans la basse stratosphère et l'examen de la distribution du traceur tungstène 185 dans la stratosphère suggèrent que les trace-substances soient transportées vers le nord de la stratosphère tropicale par l'action des procès de tourbillon transitoire dans lequel les parcelles d'air mouvant vers le nord s'enfoncent et les parcelles mouvant vers le sud s'élèvent. Le total d'ozone transporté varie periodiquement et devient maximum pendant la fin de l'hiver et du printemps. Le transport total paraît suffisant à justifier l'élévation de l'ozone observée au printemps aux latitudes moyennes et supérieures. Les tourbillons invoqués se montrent consistant au contregradient du transport de chaleur observé dans la basse stratosphère, le modèle des isentropes et les valeurs covariées se trouvent dependre des vitesses méridionales et verticales. Les résultats combinés indiquent une nouvelle vue sur les mécaniques des mouvements stratosphériques contrastant des idées classiques aux mouvements moyens méridionaux.

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The research reported in this article was sponsored by the Atomic Energy Commission under Contract No. AT (30-1) 2241 and by the Geophysics Research Directorate, Air Force Cambridge Research Center, under Contract No. AF 19 (604) 5223.     

花东海盆浊流沉积的磁性特征及其环境意义

对取自台湾以东花东海盆GX168孔的浊流沉积物进行系统的岩石磁学研究,揭示其沉积学和岩石磁学特征,分析其物源和形成机制.研究结果显示,剖面上共识别出12层浊流沉积物,其分布存在规律,下部350～700 cm共发育11层浊流沉积物,而0～350 cm仅出现1层浊流沉积物.浊流沉积物粒径明显较背景沉积物粗,石英、长石含量更高,底部与下伏背景沉积呈突变接触,顶部与上覆背景沉积呈渐变接触,内部发育典型的正粒序韵律结构.浊流沉积物和背景沉积物具有相似的磁学特征,两者均以磁铁矿为主要载磁矿物类型,且磁铁矿颗粒均以准单畴和多畴颗粒为主.同时,两者也存在一定差异,浊流沉积物中磁铁矿较背景沉积物更为富集,磁化率和饱和等温剩磁更强,磁铁矿粒径更粗,这与浊流沉积物原始沉积区更靠近物源区有关.花东海盆浊流沉积形成的诱发机制可能是末次冰期以来频发的海平面波动造成陆坡之上沉积物重力失稳,导致陆坡沉积物向海盆搬运.     

湖北金沙河水库浮游植物群落结构及其与水环境因子的关系

为探明长江中游大型水库水质状况,并为饮用水源安全保障提供科学依据,于2013 2014年按季节对湖北红安金沙河水库浮游植物群落结构及其多样性进行调查,并运用多元统计定量分析浮游植物群落结构与环境因子之间的关系.共鉴定出浮游植物8门94属216种,其中绿藻门为优势种群,其种类数占总物种数的51.39%,其次是硅藻门和蓝藻门.金沙河水库优势种随季节变化而变化,夏季以尖针杆藻(Synedra acus)的优势度最大(0.195),秋季以小胶鞘藻(Phormidium tenus)(0.180)和中华尖头藻(Raphidiopsis sinensia)(0.171)的优势度最大,冬季以具星小环藻(Cyclotella stelligera)(0.220)和圆筒锥囊藻(Dinobryon cylindricum)(0.234)的优势度最大,春季则是链状曲壳藻(Achanthidum catenatum)成为绝对优势种(0.910);金沙河水库浮游植物群落总的变化规律为夏季的硅藻门、蓝藻门和绿藻门,秋季的蓝藻门、绿藻门、硅藻门和隐藻门,向冬季的硅藻门和金藻门转变,春季则是硅藻门为绝对优势类群.Shannon-Wiener多样性指数和Pielou均匀度指数显示,浮游植物在秋季的多样性和均匀度较高,春季的多样性指数和均匀度指数显著低于其它季节,这是因为春季有绝对单一的优势物种,而秋季没有,且秋季的物种数最多,因此其Margalef丰富度指数也最高.将各季节优势种和经Pearson相关性分析筛选出的环境因子进行冗余分析,结果表明筛选的环境因子中磷酸盐、总磷和溶解氧浓度是影响金沙河水库浮游植物群落结构的主要环境因子.从藻类季节变化规律来看,金沙河水库夏、秋季水质污染程度较春、冬季严重;但从藻类丰度和多样性指数来看,春、夏季水质较秋、冬季污染严重.     

Expansion of agricultural oasis in the Heihe River Basin of China: Patterns,reasons and policy implications

The Heihe River Basin (HRB) is the second largest inland river basin in the arid region of northwestern China. An agricultural oasis is a typical landscape in arid regions providing precious fertile soil, living space and ecological services. The agricultural oasis change has been one of the key issues in sustainable development in recent decades. In this paper, we examined the changes in the agricultural oasis in HRB and analyzed the socio-economic and climatic driving forces behind them. It was found that the agricultural oasis in HRB expanded by 25.11% and 14.82% during the periods of 1986–2000 and 2000–2011, respectively. Most of the newly added agricultural oases in HRB were converted from grassland (40.94%) and unused land (40.22%). The expansion in the agricultural oasis mainly occurred in the middle reaches of HRB, particularly in the counties of Shandan, Minle, Jinta and Jiuquan city. Changes in the rural labor force, annual temperature and precipitation have significant positive effects on agricultural oasis changes, while the ratio of irrigated agricultural oases has significant negative effects on agricultural oasis changes. The agricultural oasis expansion in HRB is the combined effect of human activity and climate change.     

神农架大九湖湿地摇蚊群落组成及其环境指示意义

泥炭地是一种水-陆过渡型的湿地生态系统。水体沼泽化过程中,植被等生物群落也随之改变,进而影响泥炭地碳埋藏和发育过程。作为泥炭地生态系统重要的次级生产者,摇蚊群落结构变迁可以为追溯泥炭地环境演变和发育历史提供关键线索。泥炭地在发育过程中将经历各种不同阶段,然而,现有的泥炭地摇蚊群落调查仅限于泥炭生境或泥炭地中开阔水域,较短的生境梯度不足以提供更为全面的摇蚊群落变化信息。神农架大九湖湿地包含泥炭地、湖泊、临时性水体等多种生境,本研究选择该湿地公园作为研究区域,通过采集不同生境的表层沉积物及水体样品,提取底泥亚化石摇蚊头壳,分析大九湖湿地中不同生境下的摇蚊群落结构差异,并对其与环境因子间的关系进行探讨。结果表明:1)大九湖湿地不同生境中摇蚊优势种迥异,泥炭藓藓丘生境中Limnophyes、Psilometriocnemus、Pseudosmittia等半陆生种类为主要优势种,湖泊生境中则以典型静水种Polypedilum nubeculosum-type为主要优势种,而过渡性水域(泥炭地洼地、沟渠及水洼生境)中,静水种与半陆生种共存;2)烧失量、水位埋深和pH是塑造不同生境类型下摇蚊群落结构的显著环境因子,水文条件主要通过改变碳积累过程等其他环境条件间接影响生物群落组成;3)沿水生-半陆生生境梯度,有机质含量和类型均发生显著变化,而摇蚊群落也由静水种、静水/半陆生共存转变为以半陆生种为主,摇蚊群落对生境变化表现出良好的响应过程。本研究揭示了不同生境条件下摇蚊群落的结构差异及影响摇蚊群落结构的潜在因子,为未来基于摇蚊的长时间尺度上泥炭地发育过程分析提供参考依据。     

Fossil gastropods from the MGS3 stratigraphic segment in the Salawusu River Valley and their climatic and environmental implications

Contemporaneous with MIS3, the MGS3 segment of the Milanggouwan stratigraphic section in the Salawusu River Valley, Mu Us Desert, China contains fossil gastropods (terrestrial and freshwater snails) in strata 33LS, 35LS, 37FL and 39LS. Examination of these fossils revealed 11 species belonging to 8 families and 10 genera. They can be classified as: (1) assemblage of Gyraulus and Galba mainly consisting of Gyraulus convexiusculus, Gyraulus sibiricus, Galba pervia and Galba superegra Gredler, etc. (2) assemblage of Vallonia mainly consisting of terrestrial snails, such as Vallonia patens, Pupilla muscorum and Discus paupe, etc. Based on the dating results, and the living habits, living conditions, and geographic distribution of their extant species, we suggest that: the ages of 33LS, 35LS, 37FL, and 39LS are 26000, 29000, 33000 and 38000 a, respectively, corresponding well to the interstadial period in GRIP 4, 5, 6 and 10 in terms of chronology and climatic characters; 33LS, 35LS and 39LS represent very warm-humid periods, while 37FL represents a less warm-humid period; the four periods of climatic fluctuations recorded in MGS3 were related to the strong impact of the summer monsoon in East Asia in Mu Us Desert of China during the interstadial of MIS3 on a global climatic background.     

The spatial distribution of sedimentary compounds and their environmental implications in surface sediments of Lake Khar Nuur (Mongolian Altai)

Lake sediments are valuable natural archives to reconstruct paleoclimate and paleoenvironmental changes which consist of inorganic and organic sediment compounds of allochthonous origin from the catchment and of autochthonous production in the lake. However, for robust paleo-reconstructions it is important to develop a better understanding about sedimentation processes, the origin of inorganic and organic sediment compounds and their distribution within the lake. In this context, modern process studies provide important insights, although environmental and anthropological changes can affect the spatial distribution of sediment compounds through time. Therefore, in this study the spatial distribution of grain size and geochemical proxies in 52 surface sediment samples from Lake Khar Nuur, a small high-altitude lake in the Mongolian Altai with a small and anthropogenically used hydrological catchment, is investigated. The results show a distinct sediment focussing in the two deep basins of the lake, which therefore act as accumulation zones. In those accumulation zones, total organic carbon (TOC), total nitrogen (N) and their isotopic composition (δ¹³C_TOC, δ¹⁵N) as well as n-alkanes indicate that organic sediment compounds are a mixture of both allochthonous and autochthonous origin. While the recent catchment vegetation consists of grasses/herbs and the shrub Betula nana (L.) with distinct differences in their n-alkane homologue patterns, those differences are not reflected in the sediment surface samples which rather indicates that grass-derived n-alkanes become preferentially incorporated in the lake. Extensive anthropogenic activity such as grazing and housing in the southern part of the catchment causes soil erosion which is well reflected by high TOC, N and sulphur (S) contents and ¹⁵N depleted δ¹⁵N values at the central southern shore, i.e. increased allochthonous sediment input by anthropogenically-induced soil erosion. Overall, the surface sediments of Lake Khar Nuur origin from allochthonous and autochthonous sources and are focussed in the accumulation zones of the lake, while their distribution is both environmentally and anthropogenically driven.     

Environmental regulations of agriculture in the Baltic Sea catchment areas, with reference to the European Union and the North Sea

The environmental policies aimed at reducing nutrient emissions from the agricultural sectors in the Baltic states, Poland, Germany and Scandinavia are detailed. The emissions include leaching, run-off and erosion losses of nitrogen and phosphorus, volatile losses of ammonia, and farm waste discharges. Farm waste discharges and nitrate leaching from agricultural fields have received considerable attention during the last few decades, but more recently the remaining loss categories have also been recognized as substantial contributors of nutrients to the environment.

Environmental targets have been set in the Helsinki Commission (HELCOM) Ministerial Declaration of 15 February 1988, stating that a significant reduction (e.g. 50%) of the nutrient load to the Baltic Sea shall be reached before 1995. A similar target for the Oslo and Paris (OSPARCOM) Convention waters has been set by the North Sea ministers, while the EU Nitrate Directive expresses an environmental standard by setting an upper limit to nitrate concentrations in groundwater.

It is argued here that in most instances only marginal reductions in agricultural emissions will be achieved under the current policies before 1995 (or later). Exceptions are seen in transition economy countries where fertilizer consumption and livestock production have decreased significantly. As agriculture is a major source of nutrients to convention waters, the overall 50% reduction target will not be met. Furthermore, it is argued that there is scope for a considerable reduction of losses from agriculture and that the instruments to achieve the objectives are readily available. Measures should focus on the total input of nutrients to the agro-ecosystems and not so much attempt to regulate specific management practices. The more prominent instruments include the reduction or alteration of agricultural subsidies, market considerations and the use of environmental taxes (on fertilizers and nutrients in animal manure) combined with in-depth structural regulations. It is, however, necessary to generate further political willingness to ensure decisions and successful implementation of the various measures—a process which requires public attention.     

Empirical behaviour of tests for the beta distribution and their application in environmental research

The beta distribution is used in different models of environmental research. The power of the test for beta distribution of Raschke [Biased transformation and its application in goodness-of-fit tests for the beta and gamma distribution. Commun. Statist. B–Computa. Simula. 38 (2009): 1870–1890] is researched here. The power of the Kolmogorov–Smirnov, Kuiper, Cramér-von Mises, Watson and Anderson–Darling tests are researched for different sample sizes, levels of significance and parameters of the beta distribution. The limitation to these tests is discussed including the differences between previous publications. The empirical behaviour is investigated by extensive Monte Carlo simulations. The most powerful test for the beta distribution is the Anderson–Darling test for the considered constellations of alternative distribution, contamination or scaling. The second best test is the Cramér-von Mises test, followed by the Watson test. The analysis of relative humidity data of meteorology and of runoff coefficients of the hydrology demonstrates the advantages of the new tests and the necessity to test an assumption of beta distribution.     

Evidence for periodicities in the auroral occurrence frequency since 300 AD and their implications

Spectral analyses of the Chinese auroral records dating from 300 AD using maximum entropy, Fourier and autocorrelation methods have revealed significant periods. The power spectral density of the auroral records has a strong multiplet of spectral lines centered on the median period. The prominent period is 200 years followed by enveloping bands of 80–130, 40–60 and 20–30 years. Nonstationarity is found for periods less than 120 years.The similarity of these periods with intervals between sunspot minima and other solar-terrestrial parameters is noted     

Fluvial terraces and their implications for Weihe River valley evolution in the Sanyangchuan Basin

Fluvial terraces are important geomorphic markers for modern valley development.When coupled with numeric ages,terraces can provide abundant information about tectonic,climatic,paleohydrological and the paleoenvironmental changes.On the basis of the paleomagnetic,electron spin resonance(ESR) and optically stimulated luminescence(OSL) dating,in addition to an investigation of local loess-paleosol sequences,we confirmed that 13 fluvial terraces were formed,and then preserved,along the course of the Upper Weihe River in the Sanyangchuan Basin over the past 1.2 Ma.Analyses of the characteristics and genesis of these terraces indicate that they resulted from the response of this particular river system to climate change over an orbital scale.These changes can further be placed within the context of local and regional tectonic uplift,and represent an alternation between lateral migration and vertical incision,dependent upon the predominance of climatic and tectonic controls during different periods.Most of the terraces are strikingly similar in that they have several meters of paleosols which have developed directly on top of fluvial deposits located on the terrace treads,suggesting that the abandonment of terraces due to river incision occurred during the transitions from glacial to interglacial climates.The temporal and spatial differences in the distribution patterns of terraces located on either side of the river valley indicate that a tectonic inversion occurred in Sanyangchuan Basin at-0.62 Ma,and that this was characterized by a transition from overall uplift to depression induced by fault activity.Synthesized studies of the Basin's terraces indicate that formation of the modern valley of the Upper Weihe River may have begun in the late Early Pleistocene between1.4-1.2 Ma.     

Drought impacts on water quality and potential implications for agricultural production in the Maipo River Basin,Central Chile

ABSTRACT

Droughts can have serious negative impacts on the water quality needed for irrigated agriculture. The Metropolitan region of Chile is a relevant producer of high-value crops and is prone to droughts. Standardized Drought Indices were used to characterize meteorological and hydrological droughts for the period from 1985 to 2015. To understand the relationship between droughts and water quality, we evaluated the correlations between daily discharge and surface water quality observations. The threshold level method was used to compare physicochemical parameters during hydrological drought periods with the Chilean water quality thresholds for agricultural uses. A significant (p < 0.05) negative relationship between discharge and electrical conductivity and major ions was found in most of the basin. Hydrological stations located in irrigation districts exceeded the official thresholds for these parameters during hydrological drought periods seriously threatening irrigated agriculture of the region.     

Seasonal evolution of runoff generation on agricultural land in the Belgian loess belt and implications for muddy flood triggering

Muddy floods due to agricultural runoff are a widespread and frequent phenomenon in the European loess belt, and particularly in central Belgium. These floods are triggered when high quantities of runoff are generated on cropland and cause severe erosion. Three soil surface characteristics are relevant to determine the runoff potential of cultivated soils: soil cover by crops and residues, soil surface crusting and roughness. These characteristics have been observed on 65 cultivated fields throughout 2005. A heavy rainfall event representative for events triggering muddy floods in the region (60 mm h^?1 during 30 minutes) has been simulated using a 0·5 m² simulator on fields with the 17 most observed combinations of soil surface characteristics in central Belgium. Runoff is not observed in the case of (ploughed) bare uncrusted soils, nor in the case of soils covered by crops showing a transitional crust and a moderate roughness (1–2 cm). In the cases where runoff has been observed, mean runoff coefficients ranged from 13% (wheat in July) to 58% (sugar beet or maize in May and June). Grassed buffer strips (GBSs) and grassed waterways (GWWs) show a higher runoff coefficient (62% for GBSs and 73% for GWWs) than most cultivated soils (13–58%). Furthermore, it is demonstrated that small plot measurements can be used to estimate runoff generation at the field scale. A classification of runoff generation risk based on the surveys of soil surface characteristics has been applied to common crops of central Belgium. February as well as the period between May and September are the most critical for runoff at the field scale. However, it appears from monitoring of a 16 ha catchment that the highest runoff volumes and peak discharges are recorded between May and August after heavy rainfall, explaining why 85% of muddy floods are recorded during this period in central Belgium. Copyright © 2007 John Wiley & Sons, Ltd.     

松辽盆地深部地壳构造特征与无机油气生成模式

松辽盆地中地壳有一低速-高导层(也称塑性层),中地壳的塑性层与松辽盆地的成因以及盆山耦合系统有关.盆地地幔流体活动有下列表现:(1)高热流、高地温场;(2)深大断裂与火山岩喷溢;(3)碱交代作用(如钠长石化、伊利石化);(4)Mg2 交代作用(如白云石化)等等.地球化学省与地球化学急变带控制了大油气田的分布并显示了盆地发生的壳-幔相互作用.中地壳的低速-高导层不是岩浆岩,而是一充满地幔流体的地质体,它们富含氢、碱金属(K 、Na )、卤素(F-、Cl-)、碳(甲烷、CO、CO2)、氮、硫等.在中地壳的温度压力条件下,在Fe、Ni等催化荆的参与下,H2与CO(CO2)可发生费-托合成烃的反应.实验表明:这个反应不仅可生成气态烃还可生成液态烃,并将发生碳同位素分馏作用.松辽盆地的U形运移模型受到质疑.按照石油无机生成的模型,松辽盆地的深部将会有更多的石油与天然气,庆深气田的发现便是一个明证.     

Antioxidant and biotransformation responses in Liza aurata under environmental mercury exposure - relationship with mercury accumulation and implications for public health

This study was carried out in the Laranjo basin (Ria de Aveiro, Portugal), an area impacted by mercury discharges. Liza aurata oxidative stress and biotransformation responses were assessed in the liver and related to total mercury (Hg_t) concentrations. A seasonal fish survey revealed a sporadic increase in total glutathione (GSH_t) and elevated muscle Hg_t levels, although Hg levels did not exceed the EU regulatory limit. As a complement study, fish were caged for three days both close to the bottom and on the water surface at three locations, and displayed higher Hg_t levels accompanied by increased GSH_t content and catalase activity as well as EROD activity inhibition. The bottom group displayed higher hepatic Hg_t and GSH_t contents compared with the surface group. Globally, both wild and caged fish revealed that the liver accumulates higher Hg_t concentrations than muscle and, thus, better reflects environmental contamination levels. The absence of peroxidative damage in the liver can be attributed to effective detoxification and antioxidant defense.