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1.
Effects of acute cadmium poisoning on survival, its residual values and histopathology in certain organs of a freshwater airbreathing fish, Channa punctatus (BLOCH ) were investigated. The threshold concentration, MATC and LC50 values obtained from 96 h static bioassay, revealed that Channa is more susceptible to cadmium ions at higher temperature. The atomic absorption spectrophotometric determination of cadmium residues differed significantly in organs of specimens having survived and died after 96 h of exposure. The gill accumulate the highest amount of cadmium, the liver accumulated a slightly smaller amount than the gill, while the kidney accumulated the least. The histopathological lesions subjected to sublethal (5.2 mg/l Cd) and lethal (8.4 mg/l Cd) concentrations of cadmium were: detachment and rupture of lamellar epithelium, collapse of pillar cells and hypertrophy in mucus producing gland cells in the gill; vacuolization and coagulative necrosis in hepatic cells of the liver; and expansion, necrosis and accumulation of cellular debris in renal tubules of the kidney. The probable causes for death of fish due to cadmium ions have been discussed. 相似文献
2.
Accumulation of Pesticides in Anaerobic Clayey Till‐Controls and Implications for Groundwater 
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下载免费PDF全文 Pesticide residuals after point‐source pesticide spills in clay‐rich aquitards may potentially affect underlying groundwater for many decades due to slow release of accumulated pollution in the clayey matrix material of the aquitard. In this study, we evaluated factors behind different degrees of accumulation of phenoxy acids (MCPP, dichlorprop, 2,4‐D MCPA) and triazines (simazine and terbutylazine) observed in an old pesticide pollution described by Jørgensen et al. (2016a, this issue). By using leaching experiments, it was shown that a zone of maximum concentrations of MCPP and dichlorprop (mg/L) observed by Jørgensen et al. (2016a, this issue) represented accumulated potentially mobile pollution in anaerobic, however largely immobile pore water of the clayey matrix in the upper few meters of the unoxidized aquitard zone. By using sorption experiments, we determined 9 to16 times higher mobility by diffusion and flow for the phenoxy acids (R = 1 to 2) than for the triazines (R = 9 to 16) in the clayey matrix material of the aquitard. This indicated that more rapid and greater accumulation could occur for the phenoxy acids in the clayey matrix than for the triazines. In contrast, the relative mobility of the phenoxy acids and triazines was much closer in sand‐filled fractures and thin sand layers/lamina in the clay, suggesting that the migration of the same compounds along these textural preferential flow paths into the underlying aquifer was less different. Despite that a greater mass had originally been spilled of 2,4‐D and MCPA having similar mobility as the accumulated MCPP and dichlorprop, these compounds were not accumulated in the zone of maximum concentrations. It is suggested that the controls, which initially allowed for the observed separate accumulation of MCPP and dichlorprop as a zone of maximum pollution, were due to the combination of high persistence and high mobility for these specific pesticides in the clayey till matrix material of the aquitard. The investigation showed that over time the initial high concentrations of the accumulated phenoxy acids (MCPP, dichlorprop) transformed into high concentrations of related mobile degradation products (e.g., 4‐CPP and 2‐CPP), which extended the total time of groundwater pollution beyond the disappearance of the original phenoxyacids. 相似文献
3.
洪泛系统具有复杂动态的水文环境,在季节性洪水脉冲影响下,地表-地下水交互转化对洪泛区水循环和生态环境保护等方面具有重要意义.本文采用野外试验、统计分析和达西定律等研究方法,开展了鄱阳湖洪泛区碟形湖湿地系统(河流-洲滩湿地-碟形湖)地表-地下水文学特征、相互作用和交换通量研究.数据资料显示,在地形地貌影响下,研究区洲滩地下水位明显低于碟形湖水位,但总体上略高于周边河流水位,统计结果进一步表明,在控制洪泛湿地的地下水动态方面,河流水文情势变化对地下水的影响作用要强于碟形湖水文变化.就河流-地下水转化关系而言,研究区湿地系统的地下水与周边河流水体之间存在动态转化关系,地下水对河流的补给通量以及河流对地下水的补给通量分别约为0.4和0.2 m/d.就湖泊-地下水转化关系而言,碟形湖一般来说补给周边滩地的地下水系统,但两者之间的交换通量基本小于0.1 m/d.在年尺度上,研究区地表-地下水之间的累积交换通量变化约介于7.5~48.2 m/a,其中河流-地下水的累积交换通量约是碟形湖-地下水的4~7倍,且秋、冬季的累积交换通量要明显大于春、夏季.本文研究结果可为洪泛区河湖系统的水资源联合管理、水环境整治和生态环境保护等方面提供科学支撑. 相似文献
4.
Residues of DDT isomers accumulated in the testes of Channa punctatus (BLOCH) were quantitatively estimated by exposing the fish to 2.5 ppm sublethal concentration for 32 days. The study revealed a high accumulation of DDT residues in the testes. The maximum concentration of residues was noted on the 32nd day of the experiment. The DDT isomer accumulated in maximum concentrations was followed by DDE and DDD isomers. The maximum residue concentrations were 0.3221 ppm (DDT), 0.1119 ppm (DDE) and 0.0695 ppm (DDD) on the 32nd day of the experiment. The total DDT residue concentration at the final interval was 0.563 ppm. 相似文献
5.
植物是大型河流生态系统的重要成分。但受气候变化和人类活动影响,洲滩禾本科植物高度不断发生调整,进而影响洲滩生境和河道防洪安全,故需长期监测。近年来,伴随着星载激光雷达(LiDAR)技术的发展,应用LiDAR卫星数据反演洲滩禾本科植物高度成为一种可能。本文融合新一代星载LiDAR系统GEDI数据与Sentinel-2影像,基于XGBoost算法构建了考虑物候、累积温度与光合有效辐射指标的洲滩典型禾本科植物高度外推模型,同时利用Attention-UNet算法搭建了洪淹区域识别模型。随后以长江中游洲滩为例,探明了星载LiDAR技术在获取洲滩植株高度方面的性能,分析了各指标对模型精度的影响,并初步得出了洲滩典型禾本科植物高度对不同淹没条件的响应模式。主要结论包括:(1)星载LiDAR系统GEDI具有准确探测洲滩植物高度的能力,与无人机航测数据相比RMSE=0.43 m;(2)运用GEDI数据构建禾本科植物高度外推模型时,考虑物候和累积温度等指标可有效提升模型精度,提升幅度为6.8%～10.7%;(3)利用无人机航测数据对模型外推植物高度进行评价,RMSE=0.80m。同时从模型外推结果中可知... 相似文献
6.
This paper aims to analyse the geoelectrical resistivityρ
s
data on the dipole electrode sounding, which were firstly accumulated from the earthquake prone region in China. The analyses
on the one order difference value of the geoelectrical resistivity indicated that, firstly, more than 4 percent of theρ
s
data reveals the precursors by 3 to 76 days ahead the earthquakes occurring, with the magnitude range of 4 ≤M ≤ 6. 4, in a region of 100 km around the station, and secondly, the results revealed that the seasonal variation ofρ
s
data were slight.
The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,14, 211–219, 1992. 相似文献
7.
Dr. René Gächter Dr. Wolfgang Geiger 《Aquatic Sciences - Research Across Boundaries》1979,41(2):277-290
Phytoplankton, periphyton and zooplankton samples, chironomid andSialis sp. larvae, and fry of trout and bream collected from unpolluted and artificially metal-polluted limno-corrals were analyzed
for mercury, copper, cadmium, zinc and lead. The results indicate that these metals are not accumulated through the food chain
and suggest that increased metal concentrations in the environment favor the growth of phytoplankton organisms with a low
metal sorption capacity. 相似文献
8.
D. J. Stom S. S. Timofeeva N. F. Kashina L. J. Bielykh S. N. Souslov V. V. Boutorov M. S. Apaktzin 《洁净——土壤、空气、水》1980,8(3):241-245
Under laboratory conditions and conditions similar to practice in the shore region of the lake Baikal, Nitella was added to aqueous solutions of benzidine and α-naphthylamine in the concentration range of 10?3 … 10?4 M. The results are summarized graphically in in tables. The two substances were accumulated in the protoplasm of the Nitella cells in considerable quantities. 相似文献
9.
Sb, As, Cu, and Zn toxicity and contamination have become a growing concern in recent years. Phytoremediation, a plant based and cost effective technology, may be an effective approach in the cleanup of water contaminated by these metals. In this study, the aquatic macrophyte Eleocharis acicularis was used in laboratory and field experiments to assess its capability to accumulate Sb, As, Cu, and Zn, and thereby investigate its potential application in phytoremediation. The results showed that E. acicularis adapted well to water contaminated by these metals. The removal rates of Sb, As, Cu, and Zn in the laboratory experiment were 3.04, 2.75, 0.417, and 1.49 μg/L/day, respectively. The highest concentrations of these metals accumulated in E. acicularis after 10 days of the laboratory experiment were 6.29, 6.44, 20.5, and 73.5 mg/kg dry weight, respectively. Only 8% of As, 12% of Sb, 87% of Cu and 93% of Zn removed from the water were used by E. acicularis. The highest concentrations of Sb, As, Cu, and Zn accumulated in E. acicularis after 10 wk of the field experiment were 76.0, 22.4, 33.9, and 266 mg/kg dry weight, respectively. The results indicate that E. acicularis has the ability to accumulate Sb, As, Cu, and Zn from contaminated water. 相似文献
10.
K. S. Richards 《地球表面变化过程与地形》1981,6(2):183-186
The Dovedale Griff has incised into valley fill deposits in Staindale to expose sub-fossil wood at the base of a meander cut bank. The wood includes oak (Quercus sp.) driftwood, and apparently in situ stumps of willow (Salix sp.) and alder (Alnus sp.). An alder stump is dated at 6270 radiocarbon years BP. Fluvial gravels approximately 1±5 m thick have accumulated above the wood, which has been exposed by renewed incision. 相似文献
11.
Water–rock–gas system is simulated using a technique based on the fundamental principles of modern hydrogeochemistry regarding the formation parameters of natural-water chemistry to show that groundwater pollution hazard at a gold-bearing placer is acute for any site of water exchange changing from passive to active. Under passive water exchange, the products of sulfide oxidation are accumulated; whereas under active water exchange, the oxidation products are leached out to form acid drainage flows. The treatment of acid drainage water and the neutralization of acid solutions are more effective under reduction or weakly alkaline conditions. 相似文献
12.
Rhizofiltration is a subset technique of phytoremediation which refers to the approach of using plant biomass for removing contaminants, primarily toxic metals, from polluted water. The effective implementation of this in situ remediation technology requires experimental as well as conceptual insight of plant–water interactions that control the extraction of targeted metal from polluted water resources. Therefore, pot and simulation experiments are used in this study to investigate the rhizofiltration of a lead containing wastewater using plants of Carex pendula, a common wetland plant found in Europe. The metal contaminant extraction along with plant growth and water uptake rates from a wastewater having varying Pb concentration is studied experimentally for 2 wk. The temporal distribution of the metal concentration in the wastewater and the accumulated metal in different compartments of C. pendula at the end are analyzed using atomic absorption spectrometry. Parameters of the metal uptake kinetics are deduced experimentally for predicting the metal removal by root biomass. Further, mass balance equations coupled with the characterized metal uptake kinetics are used for simulating the metal partitioning from the wastewater to its accumulation in the plant biomass. The simulated metal content in wastewater and plant biomass is compared with the observed data showing a good agreement with the later. Results show that C. pendula accumulates considerable amounts of lead, particularly in root biomass, and can be considered for the cleanup of lead contaminated wastewaters in combination with proper biomass disposal alternatives. Also, the findings can be used for performing further non‐hydroponics experiment to mimic the real wetland conditions more closely. 相似文献
13.
Analytical and experimental study on dissolved pollutant wash‐off over impervious surfaces 下载免费PDF全文
下载免费PDF全文 Non‐point source pollution in the impervious surface of city, which including dissolved and particulate pollutants, is a significant source of water pollution. Simple first‐order decay models can generally simulate the cumulative wash‐off process of the particulate pollutants. There is inadequate knowledge as to whether or not they are suitable for dissolved pollutants. This study presents a mathematical wash‐off model for dissolved pollutants, which combines analytical equations for overland flows and the exponential equation for the pollutant wash‐off. A series of laboratory experiments have been conducted to verify this wash‐off model. It shows that the pollutant concentration and pollutant transport rate can be predicted well by the newly developed equations. It is found that the pollutant concentration monotonically decreases to zero as the accumulated pollutants are washed off, whereas the pollutant transport rate first increases to the maximum value and then decreases to zero. The maximum pollutant transport rate is found to increase with the decrease of the arrival time of the maximum value. The difference between the simplified exponential model and the amended wash‐off equation depends on the initial residual percentage (Pc), but the present equation generally provides a more accurate representation of the wash‐off process of dissolved pollutants. 相似文献
14.
V. P. Trubitsyn 《Izvestiya Physics of the Solid Earth》2010,46(11):922-930
Basalts of mid-ocean ridges are depleted in incompatible elements that have passed into the continental crust. Basalts of
hot spots (oceanic islands and igneous provinces) have a chemical composition close to the primary uniform mantle and are
even somewhat enriched in incompatible elements. At present, for explaining the reason for this difference, there are different
qualitative schemes of differentiation and mixing of substance in the mantle. In the present work, the results of numerical
modeling of the two-component thermochemical convection in the mantle are given. They quantitatively demonstrate with which
parameters in the mantle the layers of different chemical composition can remain unchanged. Models with different density
contrasts and with variable viscosity are examined. The times of the partial mixing of layers depending on the values of these
parameters are calculated. For retaining the stratified mantle for two Ga, the density contrast must be more than 2%. If the
layer D″ contains a substance of the primary composition, then, its upper boundary can be the place of origin of the plumes that
feed the hot spots of the Earth. The enrichment in the incompatible elements and the variety of the chemical composition of
hot spots can be explained by the mixing of the substance of the slowly eroded D″ layer and the oceanic crust accumulated in it. 相似文献
15.
From April 1997 to June 1998 Nemurella pictetii populations were regularly sampled in two springstreams at 220 and 850 m a.s.l., respectively, in Hesse (Germany), at approximately 51°N. Random samples of larvae were taken at three week intervals during the vegetation period, and once a month during winter. Sex, instar, body length, head capsule width and wing pad length of all larvae were recorded. Temperatures were recorded every hour, temporal patterns of temperature agreed closely between sites. Mean winter lows were 3.9 °C at both sites, the mean summer high was 11.9 °C at the lower site, as opposed to 9.6 °C at the mountain site.At both sites, adult emergence started in May. At the mountain site, recruitment started in late July and continued into autumn. There was cohort splitting in the young generation. Some individuals grew rapidly until October–November, but last instar larvae first appeared in March the next year. 1600 degree-days above 0 °C were accumulated during complete development. At the lower site, recruitment began in early July, and cohort splitting also occurred. Fast growing summer recruits emerged as adults in late August, having accumulated only 700 degree-days (above 0 °C). Their offspring hatched in November-December and emerged the next spring, having accumulated also only 700 degree-days. However, only part of the population was bivoltine. Many of the summer recruits grew more slowly and accumulated close to 1900 degree days until they emerged the next spring, together with the offspring of their own fast-growing siblings. Dependence of growth rate on temperature could not be estimated and appears to vary with daylength. For example, 3–6 °C support growth and development provided daylength exceeds 10 hrs of light, or is rising.At both sites and in all cohorts individuals emerging earliest were larger than later emerging ones. The size decline is significantly correlated with number of days after the winter solstice. For the first time it is shown that the decline does not occur shortly before adult emergence but actually takes place several instars before the last. Size differences are then carried on, and amplified, during subsequent molts, until adulthood. The literature presently relates seasonal size declines of insects to high or rising temperatures experienced by larvae approaching adulthood. Our data show that, at least in Nemurella, this explanation fails. On average, females were distinctly larger than males. Differences in mean last instar size were noticed also between sites and years. They remain presently unexplained. The mean sex ratio in both populations was close to 1:1. 相似文献
16.
The effects of DDT on the regeneration of cutaneous wounds has been studied in Mystus (mystus) vittatus. The fishes were locally collected, they were inflicted incised wounds surgically and kept in 0.01 and 0.15 ppm concentrations of DDT. The regenerating skin at different stages of development ranging from 15 min to 25 d after the injury was studied through microtomy sections. The following toxic effects were studied:
- A small amount of DDT accumulated in the subcutis at the 25 days stage,
- the regeneration of wounds under DDT stress has been slower, delayed or irregular,
- the secretion of fibrinous exudate has been copious,
- epithelization and fibroblastic activities have been slower,
- the higher concentration of 0.15 ppm of DDT produced more toxic effects than the lower concentration of 0.01 ppm,
- the earlier stages of wound healing up to 3 d have been more adversely affected than later stages.
17.
Different morphology of Nuphar lutea in two contrasting aquatic environments and its effect on ecosystem engineering 下载免费PDF全文
下载免费PDF全文 Jonas Schoelynck Kris Bal Veerle Verschoren Ellis Penning Eric Struyf Tjeerd Bouma Dieter Meire Patrick Meire Stijn Temmerman 《地球表面变化过程与地形》2014,39(15):2100-2108
Aquatic plants (macrophytes) can have a large effect on river hydraulics and geomorphology. Though, the extent to how plant morphological plasticity actively influences these feedbacks has received little scientific attention. The nymphaeid macrophyte species Nuphar lutea (L.) Smith is characterized by a distinct leaf duality. Floating leaves shade most of the submerged leaves thereby limiting light penetration in the water. Despite their apparent negligible photosynthetic role, submerged leaves of N. lutea remain intact during summer and contribute a significant part to the total biomass. Our results indicate that the submerged leaves are crucial in plant–flow interactions and hence in the engineering potential of the plant, i.e. the capacity to locally reduce flow velocities and to promote sedimentation, including organic matter deposition. Plant individuals growing in running river water were compared to individuals from adjacent oxbow lake water. The number and size of submerged leaves were significantly higher for river standing individuals and the accumulated sediment contained significantly more organic matter, total nitrogen and total phosphorus, and was characterized by a lower carbon/nitrogen ratio and a finer grain size. We therefore argue that the submerged N. lutea canopy in rivers has the ability to create a high‐nutrient, low hydrodynamic environment, resembling the conditions found in oxbow lakes. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
18.
19.
MA Haiping WANG Qian ZHANG Bo WU Shanyi WANG Pengtao DOU Xiying LI Minjuan 《中国地震研究》2020,34(2):210-218
To study the crustal movement in the vicinity of the epicenter before the Zhangye MS5.0 earthquake in 2019, the characteristics of crustal deformation before the earthquake are discussed through the GPS velocity field analysis based on the CMONOC data observed from GPS. The baseline time series between two continuous GPS stations and the strain time series of an area among several stations are analyzed in the epicenter area. The resulting time series of baseline azimuth around the epicenter reflects that the energy of the fault in the northern margin of Qilian Mountain is accumulated continuously before 2017. Besides, the movement trend of azimuth slows down after 2017, indicating the stress accumulation on both sides of the seismogenic fault zone has reached a certain degree. The first shear strain and EW-direction linear strain in the epicentral area of the Zhangye MS5.0 earthquake remain steady after 2017, and the surface strain rate decreases gradually after 2016. It is illustrated that there is an obvious deformation loss at the epicentral region three years before the earthquake, indicating that a certain degree of strain energy is accumulated in this area before the earthquake. 相似文献
20.
Judith Hebelen Rodriguez Eduardo Daniel Wannaz María Luisa Pignata Andreas Fangmeier Jürgen Franzaring 《洁净——土壤、空气、水》2012,40(12):1315-1319
In order to study the pollution gradient in the vicinity of a large aluminium production facility in Patagonia (Argentina), a passive biomonitoring was performed employing foliage from three tree species. Primary scope was to identify pollution gradients and to select suitable tree species which can be used as biomonitor plants in the study area. Therefore, leaves of Eucalyptus rostrata, Populus hybridus and different needle ages of Pinus radiata were collected at different distances from the industry and the fluoride concentration was analysed in washed and unwashed samples in order to determine the amount of external fluoride. Washing reduced the F‐concentrations by 24, 39 and 51% on average in E. rostrata, P. hybridus and P. radiata, respectively, indicating that species‐specific characteristics determine the accumulation and wash‐off of dust‐associated fluorine. F‐concentrations varied from 6 to 3652 ppm F in unwashed samples indicating a steep pollution gradient in the study area. The influence of F‐emissions was discernible in all samples up to a distance of 3500 m from the smelter. E. rostrata accumulated more fluorine than the other species at equal distance from the emission source. The present study confirms that aluminium smelting results in high F deposition in the study area. Establishing a biomonitor network around large emitters is suitable and feasible to evaluate the efficiency of air control measures. 相似文献