Changes in mercury levels in lake whitefish (Coregonus clupeaformis) and northern pike (Esox lucius) in the LG-2 reservoir since flooding

After flooding of the LG-2 reservoir in 1978–1979, it was noticed that Hg levels in fish rose dramatically. In this study the Hg data have been examined on the basis of fish age for lake whitefish (Coregonus clupeaformis) and northern pike (Esox lucius), representing two different trophic levels. Data were fit to Von Bertalanffy functions using non-linear regression analyses. Reductions in error sums of squares indicated that differences among years were the major sources of variation, but that there were differences among stations within years. For age profiles both species showed changes after flooding, whitefish increasing immediately and remaining similar until 8 years after flooding, with decreases afterward, while pike continued to increase until 8 years after flooding, remaining somewhat stable afterwards. For whitefish, cohorts (year classes) from before flooding had similar concentrations, with maxima reached by around 1982, concentrations afterward remaining stable. Subsequent cohorts reached plateaus at around 2–4 years of age, each successive cohort having a lower plateau. For pike, Hg kept increasing in an almost linear fashion, cohorts from before flooding having similar concentrations. Analyses indicated the very gradual return of whitefish to conditions present before flooding, while pike were remaining at much higher levels. Inputs to older pike were therefore not decreasing, but younger pike may have been improving.     

Mercury in the surface water of Swedish forest lakes —concentrations,speciation and controlling factors

Concentrations of total Hg and five operationally defined Hg species were determined in the surface water of 25 Swedish forest lakes of different type. Regional and seasonal variations were studied during the ice-free season of 1986. The concentration of total Hg was usually in the range of 2 to 10 μg m-3. Hg concentrations were highly correlated to the concentration of humic matter measured as water color. Hg concentrations were about twice as high in acidic lakes (pH 5) than in circumneutral lakes, which is attributed basically to the acidity of humic compounds acting as Hg carriers in boreal waters. Significant seasonal variations were caused by hydrological processes. During periods of high water flow, Hg concentrations increased dramatically, especially in humic lakes. Between spring and autumn, chemically reactive Hg compounds were gradually replaced by more inert species. Hg/C ratios were higher than in surface runoff from forest watersheds, indicating a significant impact of direct deposition of Hg on lake surfaces during summer. Regional differences were small despite differences in Hg contamination.     

Losses and recoveries of fish populations in acidified lakes of southern Finland in the last decade

Acid-induced fish damage in small lakes in southern Finland was studied in a fish status survey of eighty lakes from 1985–1987. Later, twenty of these lakes were selected for further monitoring. A sampling of these lakes from 1988–1989 showed that the decrease in some perch (Perca fluviatilis L.) and roach (Rutilus rutilus L.) populations still continued. The results from the same lakes in 1992 showed that successful reproduction had taken place with many of the perch populations that had been close to extinction in 1985. In contrast, no signs of recovery in the roach populations were detected. The explanation for the appearance of new cohorts of perch could have been the decrease in acid deposition but the exceptional hydrological conditions of winters in the early 1990s may also have affected them. The different responses of the perch and roach populations were interpreted as a consequence of the different sensitivity of these two species to acidification. Even a slight improvement in the water quality has resulted in the appearance of strong new year-classes of perch, but not of roach. Therefore, more improvement in water quality is needed until a sensitive species like roach can reproduce again.     

Heavy metals in perch (Perca fluviatilis L.) from two acidified lakes in the salpausselkä esker area in Finland

Hg concentrations in muscle and Cd, Pb, Al, Zn and Fe concentrations in muscle, liver and kidney ofPerca fluviatilis from two acidified lakes in the Salpausselkä esker area in Southern Finland were studied. The metal concentrations in perch from the Tiilijärvi lakes were similar to those in other acidified Finnish lakes. Only Hg concentrations correlated strongly with the age and size of perch. The need for age correction in studies on the Hg concentrations on perch was noticed. The highest concentrations of Cd, Pb and Zn occured in kidney and those of Al and Fe in liver.     

A new variant of arcelin in wild common bean, Phaseolus vulgaris L., from southern Mexico

Arcelin, a seed protein discovered in wild Phaseolus vulgaris L. accessions, gives high levels of resistance to the Mexican bean weevil [MBW; Zabrotes subfasciatus (Boheman)]. Six variants of arcelin have been described. In this paper we report on a new variant, arcelin 7, found in six wild bean accessions collected in the southern state of Chiapas in Mexico. The new variant is clearly distinct from previously reported ones. It confers high levels of resistance to MBW, comparable to those due to the presence of arcelin 1, arcelin 2 and arcelin 4. Accessions containing arcelin 7 were not as resistant as the one containing arcelin 5 but significantly better in terms of resistance than arcelins 3 and 6. Arcelin 7 was found in a poorly sampled area of Mexico threatened with genetic erosion due to expanding agricultural operations. This exemplifies the need for urgent additional collecting efforts.     

Retention of phosphorus in soil and vegetation of a buffer zone area during snowmelt peak flow in southern Finland

In regions with a distinct winter-period, nearly half of the annual runoff occurs during a short snow-melt period early in spring. During this time functioning buffer zones are important means of preventing the leaching of phosphorus from forest land into downstream watercourses. Sparse vegetation restricts biological P accumulation and high flows reduce the capacity of deeper soil layers to adsorb P, indicating that the effectiveness of buffer zones may be low. Our aim was to increase the understanding of phosphorus retention in a buffer zone area under such unfavourable conditions for P removal, and to estimate the amount of P sorbed by soil and taken up by vascular plants and mosses. Over a five-day period in spring we added 10kg (60kg ha^-1) of PO₄-P and 185MBq (1100MBq ha^-1) ³²P to a 25-50m wide buffer zone area (0.17ha) in southern Finland. We measured the total P retention and recovery during ten days after the beginning of the experiment. Recovery of ³²P was 16% of added P, of which 90% was in soil, 3% in vascular plants and 5% in mosses. Thus, our results showed that the total P retention was low, most likely because the water flow did not slow down sufficiently and penetrate deeply enough to enable a close contact between P in the runoff and the soil matrix. Most of the recovered P was in the soil suggesting that adsorption by soil was the most important sink for P under early spring high flow conditions.     

Field evaluation of phenology and success of hardy,micro-propagated old shrub roses in northern Finland

Abstract

Five old shrub rose taxa were studied in field experiments in northern Finland during the years 1993–1999. The plant material was micro-propagated from woody plants selected for their ornamental value and hardiness for northern areas of Finland. The observations in the experiments were based on phenological monitoring and survey of plant success. The results revealed significant differences in the success of the different rose genotypes, and the most valuable genotypes were identified. Micropropagation was successfully used as a propagation method and these in vitro propagated roses grew naturally under harsh field conditions. The Rosa ‘Tornedal’ origins, R. ‘Poppius’ and R. ‘Sipi’ were ranked the most suitable cultivars for northern landscaping. Overall, all of the studied roses succeeded fairly well.     

基于小流域尺度的黔北喀斯特地区产流产沙特征

目前,中国西南喀斯特地区流域尺度产流产沙长期定位观测试验报道较少,且其相关机制的探讨不足。该文基于小流域尺度,分析典型喀斯特小流域产流产沙特征,定性、定量探讨喀斯特小流域产流产沙的主要影响因子。选取位于贵州北部的典型喀斯特小流域—遵义浒洋水小流域为研究区,采用小流域控制站定位观测法,在4年连续观测的基础上,分析浒洋水小流域月际、年际产流产沙特征,并重点分析了降雨对小流域产流产沙的影响。结果表明:受喀斯特地区特殊的"二元"侵蚀环境等因素影响,浒洋水小流域产流、产沙高峰不同期,产流高峰出现在10月,多年月均值为63.9万m3,而产沙高峰为6月,116.21t。显著性检验则表明,浒洋水小流域月际产流无显著差异(P0.05),但6月产沙则显著高于1、2、3及12月(P0.05),其他月份间产沙无显著差异(P0.05);受年度降雨的影响,2010-2013年,无论是产流还是产沙,2013年均显著高于其他年份(P0.05)。研究期间,小流域多年平均输沙模数为215.32 t/(km2·a),这一结果与贵州省公布的贵州喀斯特区土壤侵蚀模数279.47t/(km2·a)接近;该小流域降雨对产流产沙影响显著,降雨强度(I60)同产流产沙在0.05水平上显著相关,而降雨量同产流产沙则在0.01水平上显著相关。结果可为喀斯特地区的水土流失治理提供参考。     

Chemical,biological and socio-economic approaches to the liming of Lake Alinenjärvi in southern Finland

The aim of this comprehensive study is to estimate the effects and usefulness of liming Lake Alinenjärvi based on chemical, biological and socio-economic studies. Methodological standpoints concerning the limestone dissolution rate, acidic surges and reacidification are also discussed. L. Alinenjärvi (0.4S km²) is located near the city of Nokia with a surrounding population of over 5 000 (< 2 km). Before liming, the lake had only a sparse crayfish (Astacus astacus L.) population left, because reproduction had been failing since the early 1980s. The most important effect of liming is that it should connect with the potential production of crayfish. The roach (Rutilus rutilus L.) population was also affected. The liming improved the chemical quality of the water, and decreased also the Al and Mn concentrations. The number of phytoplankton species increased, and the species composition of periphyton changed after liming. The a-chlorophyll concentration in water remained low. Furthermore, crustacean zooplankton and benthic animals increased in abundance in the first late summer after liming. The diet analysis of perch (Perca fluviatilis L.) gave comparable results suggesting a possible positive effect of liming on their food resources. The improved water quality seems to make the reproduction of the crayfish possible again, but recovery would take several years. To guarantee a recovery, the introduction of new crayfish individuals and supplementary neutralizing methods would be needed. The results of a mailed survey showed that L, Alinenjärvi is a valuable water source for the local people. The most usual forms of leisure around the lake and shores are, however, outdoor recreation and swimming, with only minor usage for fishing. Despite that, though the immediate benefits would be negligible, a majority of local residents supported the continuation of liming even though they would have to carry the costs in the future.     

鲁中南山区马蹄峪小流域土壤有机质和全氮空间分布特征

以鲁中南山区马蹄峪小流域土壤为对象,综合考虑土地利用和采样点的代表性及可操作性,采集表层(0～20 cm)土壤样品97个,利用回归克里格方法和“3S”技术,分析小流域土壤有机质和全氮的空间分布特征.结果表明:1)马蹄峪小流域表层土壤有机质和全氮质量分数平均值分别为20.45和1.18 g/kg,变异系数分别为27.68...     

Mercury anomalies in lake water and in commercially harvested fish,Kaminak Lake area,district of Keewatin,Canada

Mercury (Hg) was measured in approximately seven hundred samples of surface water collected from Kaminak Lake and nearby small and large lakes in a tundra environment located west of Hudson Bay. Mercury variations were expected to be related to sulphide mineralization, and patterns of Hg enrichment were to be used as pathfinders for locating potentially economic sulphide deposits. Water in the northern part of Kaminak Lake, which is underlain by sedimentary and volcanic bedrock with known potential for sulphide (base metal) mineralization, was consistently enriched in Hg, as were smaller lakes lying along the same bedrock trend. Mercury concentrations in lake trout from a commercial fishery on Kaminak Lake ranged from 0.57 ppm (parts per million = mg/kg or mg/l) to 2.0 ppm Hg (70 samples), exceeding the national consumption guidelines of 0.5 ppm. Subsequently, the Kaminak fishery was abandoned and relocated on nearby Kaminuriak Lake where similar fish species averaged less than 0.5 ppm Hg. High Hg concentrations in fish from this remote, unpopulated region, far from industrial sources of pollution, are related mostly or wholly to local geological phenomena.     

Soils of northern spurs of the Cherskii Ridge in the area of the northern pole of cold: Morphology,properties, and classification

The soils in the area of the northern pole of cold located on the interfluve between the Yana and Adycha rivers within the spurs of Kisilyakh Ridge included in the mountain system of Cherskii Ridge have been studied for the first time. The profile-genetic approach has been applied to describe the soils and determine their classification position. It is found that the major soil types in this region are the soils of the postlithogenic trunk belonging to the orders of lithozems (Cryic Leptosols), gley soils (Gleyic Skeletic Cryosols), and Al–Fe-humus soils (Spodic Skeletic Cryosols). The ecological ranges of altitudinal zones— the taiga zone with various types of lithozems below 630–700 m a.s.l. and the tundra zone with combinations of gley and nongley cryogenic soils above these heights—have been established. The development of gley or nongley soils is specified by the local orogenic and lithological conditions and slope aspect, which, in turn, control the degree of drainage and the presence and character of permafrost. In the profile of mountainous gley soils (gleyzems) with shallow ice-rich permafrost, cryogenic processes and features typical of the analogues of these soils on plains—cryogenic cracking, cryoturbation, solifluction, thixotropy, oxiaquic features above permafrost, saturation of the soil profile with mobile humus, etc.—are typical.     

Growth,Survival, Protein Content,and Phytoremediation Potency of Various Rangeland Plant Species (Medicago polymorpha L., Medicago rigidula L., and Onobrychis sativa L.) Grown in Vermicompost-Containing Potting Media

A pot experiment based on completely randomized factorial arrangement design with four replications was conducted under greenhouse condition at Malayer University, Malayer, Iran. Pots contained a mixture of soil and different concentrations (0% and 60% w/w) of vermicompost. Plants were exposed to three lead nitrate concentrations: 0, 4, and 8 mM. Based on the results of this research, shoot height and root length of the studied plants significantly decreased with increased lead concentrations in all vermicompost application levels. Generally, plants exposed to lower levels of lead and vermicompost application had higher root:shoot ratio. The survival capacity of all the studied plants was significantly reduced with increased lead concentrations, but increased with increased vermicompost application level. The total protein content increased with decrease in lead nitrate concentration, but decreased with decrease in vermicompost application. Generally, translocation factor increased significantly as vermicompost application rate increased. The highest root concentration factor of lead was found in V1×Pb2 as compared to the other treatment levels. Generally, tolerance index values of all the studied plants were significantly higher in the lower lead concentration treatments.     

Toxic concentrations of iron and manganese in leaves of phaseolus vulgaris L. growing on freely‐drained soils of ph 6.5 in northern Tanzania

Abstract

A bronzing symptom of trifoliolate leaves of Phaseolus vulgaris is described which has been found to be widespread on the southern slopes of the Meru and Kilimanjaro massifs in northern Tanzania. The symptom occurred on plants growing on freely‐draining soils of moderate pH and has led to complete loss of yield of badly affected plants. Leaves with the bronziug symptom contained large concentrations of iron (>3080 mg/kg) and manganese (>760 mg/kg) considered to be toxic in Phaseolus.     

Influence of Quercus ilex trees on herbaceous production and nutrient concentrations in southern PortugalElena Cubera1, 2

In an open woodland in Portugal, the nature of interactions between Quercus ilex trees and herbaceous plants was assessed during 2 years by studying how manipulation of incident solar radiation, water and nutrient supply affect the herbaceous biomass and N, K, P, Ca, Mg, and Mn concentrations. Measurements were carried out in three environments consisting of (1) open grassland, (2) beneath the tree canopy, and (3) under artificial shade. Each of these environments was subjected to two regimes of fertilization and two water levels in a factorial design. The fertilizer treatment consisted of application of no fertilizer or a combination of 200 kg calcium ammonium nitrate ha^–1 (26% N) and 350 kg superphosphate ha^–1 (8% P), while the water‐supply treatment consisted of either no irrigation or irrigation fortnightly from February 1 to April 30. Grasses showed significantly lower nutrient concentrations than forbs. However, nutrient concentrations of the whole herbaceous community were within the recommended ranges for cattle nutrition. A negative effect of shade on herbaceous biomass production was observed. The effect of watering on herbaceous biomass was less prominent than the effect of fertilization, irrespective of the environment, suggesting that Q. ilex does not compete for soil‐water resources with herbaceous biomass in this ecosystem. Fertilization increased total biomass by 106%, 49%, and 97% in the open grassland, beneath the tree canopy, and under artificial shade, respectively. During the first and second year, fertilization increased herbaceous P concentrations by 24% and 83%, respectively, if compared with concentrations obtained at the unfertilized plots. Higher K and Mg concentrations were observed in herbaceous plants beneath the tree canopy than in the open areas, indicating a positive effect of trees on pasture quality. The positive and negative effects of trees on understory forage are discussed.     

The effects of low pH,low calcium concentrations and elevated aluminium concentrations on sodium fluxes in brown trout,Salmo Trutta L.

The effects of pH (c. 7.0, 5.4, 4.5 and 4.0), nominal Al levels (0 and 8 μmol L^?1) and Ca levels (10 and 50 μmol L^?1) on Na influx, efflux and netflux of brown trout have been investigated using artificial lake water of known composition. Low pH had little effect on influx, but tended to increase efflux, particularly in the low Ca treatments. A nominal addition of 8 μmol Al L^?1 at pH 4.5 and 4.0 reduced influx significantly. Efflux was unaffected. Aluminium addition at pH c. 7.0 and 5.4 had no such effect. The measured Al concentrations at the end of the static 8 hr flux measuring experiments were markedly lower than the nominal amount of A1 added to the start.     

土石山区护坡草本植物根系抗拉力学特性

为了解山西省土石山区护坡植物的根系抗拉力学特性,对比选择最适宜的水土保持物种.对其边坡上黑麦草(Lolium perenne L.)、香根草(Vetiveria zizanioides L.)、百喜草(Paspalum notatum Flugge)3种护坡植物的根系开展抗拉力学试验,研究3种植物根系最大抗拉力、极限抗拉强度以及弹性模量随直径及根长大小变化的规律.研究结果显示:根长一定时,3种植物的最大抗拉力随直径的增加而增加,单根极限抗拉强度随根系直径的增大而减小;而直径一定时,根系最大抗拉力和极限抗拉强度随根系长度的增大而减小;弹性模量值随着根径和根长增大呈下降的趋势.3种植物根系平均最大抗拉力关系为:香根草(16.258 N)＞黑麦草(11.734N)＞百喜草(4.891 N);平均极限抗拉强度关系为:百喜草(116.226 MPa)＞黑麦草(50.839 MPa)＞香根草(49.650MPa);平均弹性模量分别为:百喜草(20.392 MPa/mm)＞香根草(3.257 MPa/mm)＞黑麦草(3.245 MPa/mm).结果表明这3种植物中百喜草根系的固土能力最好,在选择最为适宜的水土保持物种时可优先考虑.研究结果可为土石山区水土保持研究提供一定的科学依据.     

Investigation of sulfonamide, tetracycline, and quinolone antibiotics in vegetable farmland soil in the Pearl River Delta area, southern China

Thirteen antibiotics in soil from vegetable farmlands of the Pearl River Delta, southern China, were investigated. At least three antibiotics were detected in each sample. Six antibiotics including four quinolones, tetracycline, and sulfamethoxazole were detected in >94% of the samples. The total contents of three tetracyclines, eight sulfonamides, and four quinolones were not detected-242.6, 33.3-321.4, and 27.8-1537.4 μg/kg, respectively. The highest antibiotic concentrations were observed mainly in vegetable farmlands affiliated with livestock farms. Chlortetracycline, sulfameter, and quinolones in some samples exceed the ecotoxic effect trigger value (100 μg/kg) set by the Steering Committee of Veterinary International Committee on Harmonization. The composition and concentration of antibiotics in soil were correlated with vegetable species. This study has revealed an alarming condition of antibiotics in vegetable farmland soil. Further investigation including environmental fate, plant uptake, and human exposure to antibiotics by plant-derived food should be conducted.     

Soil physicochemical properties in a high-quality tea production area of Thai Nguyen province in northern region,Vietnam

This study investigated general physicochemical properties of tea garden soils at the alluvial plain of Cong River in Tan Cuong commune, Vietnam. Four gardens were selected as study sites on three transect lines established perpendicularly to the river. Soil samples were collected from the surface (0–10 cm) and subsurface (20–30 cm). Soil texture classes varied from sandy loam to light clay, which was affected by different terrains along the transect lines as well as severe disturbance such as terracing and earth excavation. The levels of total C and total N were correlated with increasing garden age, suggesting the replenishment of soil organic matter pool by the addition of plant residue and manure. Meanwhile, the soils showed strongly acidic nature with the average pH(H₂O) of 3.7 at the surface and 3.9 at the subsurface. The effective cation exchange capacity (ECEC) was low at 4.7 and 4.9 cmol_c kg^?1, respectively, and dominated by exchangeable Al³⁺. Soil acidification was exacerbated with increasing garden age. However, a relatively large saturation of exchangeable calcium (Ca²⁺), potassium (K⁺), and magnesium (Mg²⁺) on the ECEC was found in the surface soils. The levels of available P were high, occasionally exceeding 1000 and 500 mg kg^?1 at the surface and subsurface, respectively. In spite of strongly acidic condition, ammonium (NH₄-N) applied as fertilizer was converted to nitrate (NO₃-N) to move down to deeper layers. The levels of the bases, P, and mineral N seem to be principally determined by management practices. Significant portion of these nutrients was likely to exist in water soluble forms without adsorption onto soils. It should be required to develop proper schemes and to educate the owners for adequate fertilizer managements.