Comparative analysis of land use and lake water quality in rural and urban zones of south Chennai, India

Chennai city, the capital of Tamil Nadu state in South India, has been experiencing rapid expansion since the last two decades, resulting in major changes in land use and degradation of wetlands. Small lakes in the peri-urban areas face severe strain on their environment due to transition of rural to urban conditions, leaving at stake their aquatic health and intended uses. This paper studies the role of urbanization and land use changes in the water quality of peri-urban (Rajakilpakkam) and rural (Vengaivasal) lakes. Water samples were collected and analysed for temperature, total dissolved solids, major ions, nutrients and biological oxygen demand as per standard methods. The temperature, pH and biological oxygen demand did not differ between lakes, while total dissolved solids (p = 0.008), alkalinity (p = 0.000), total hardness (p = 0.001) and phosphate (p = 0.000) were significantly higher in Rajakilpakkam. Seasonal and spatial variations in water quality between the lakes showed the direct impact of rapid and uncontrolled growth of built-up areas in the catchment area, in enhancing waste water inflows with inorganic salts and nutrients in Rajakilpakkam lake compared with Vengaivasal lake. Urbanization of the catchment and encroachments in Rajakilpakkam lake tends to reduce the social interdependence of lake and community and promote disuse, leading to decline in water quality. The impending environmental costs caused by urbanization to these lakes will only be tackled, if the main issues of domestic and industrial discharges and encroachments are addressed properly.     

On the Classification of Aquatic Communities: An Example of Zooplanktonic Cenoses of Karst Lakes in the North of European Russia

Nine lakes in the Arkhangelsk oblast were analyzed with respect to their morphometry, hydrology, and hydrochemistry, and their zooplankton was studied for three years. The data on zooplankton abundance, biomass, the ratio of filter-feeders and predators, the Shannon index of species diversity, and average individual weight of zooplankters were obtained. Differences in the structure of zooplanktonic cenoses were revealed in lakes differing in morphometric parameters, prevailing ions (HCO₃ ^–, SO₄ ^2–), and their concentration.     

Abundance and diversity of aquatic macroinvertebrate communities in lakes exposed to Chernobyl-derived ionising radiation

Littoral (lake shore) macroinvertebrate communities were studied in eight natural lakes affected by fallout from the Chernobyl accident. The lakes spanned a range in ¹³⁷Cs contamination from 100 to 15500 kBq m⁻² and estimated external dose rates ranged from 0.13 to 30.7 μGy h⁻¹. General linear models were used to assess whether abundance of individuals, taxon richness, Berger-Parker dominance and Shannon-Wiener diversity varied across the lakes. Step-wise multiple regressions were used to relate variation in total abundance, taxon richness, Berger-Parker dominance, Shannon-Wiener diversity, taxon richness within major groups of macroinvertebrates and abundance of the more common individual taxa to the measured environmental characteristics (conductivity, pH, total hardness and phosphate; lake area, lake maximum depth and total external dose) of the lakes. No evidence was found in this study that the ecological status of lake communities has been influenced by radioactive contamination from the Chernobyl accident. Indeed, the most contaminated lake, Glubokoye, contained the highest richness of aquatic invertebrates. Taxon richness in the eight study lakes varied from 22 (Svyatskoe #7) to 42 (Glubokoye) which spans a range typical for uncontaminated lakes in the region. Since ⁹⁰Sr is readily-absorbed by Mollusca, estimated dose rates to this group exceeded those for other invertebrate groups in two lakes (Perstok and Glubokoye). However this study found no association between mollusc diversity or abundance of individual snail species and variation between lakes in the external radiation dose. Indeed Glubokoye, the lake most contaminated by ⁹⁰Sr, had the highest richness of freshwater snails per sample (an average of 8.9 taxa per sample).     

Inventories of Pu, Cs, and excess Pb in sediments from freshwater and brackish lakes in Rokkasho, Japan, adjacent to a spent nuclear fuel reprocessing plant

We investigated the vertical profiles of ^239+240Pu, ¹³⁷Cs, and excess ²¹⁰Pb (²¹⁰Pb_ex) in sediment core samples obtained from two freshwater lakes and two brackish lakes situated near the first commercial spent nuclear fuel reprocessing plant in Rokkasho, Japan, before the final test of the plant using actual spent nuclear fuel. The inventory of ^239+240Pu in those lakes was larger than that in soil in Rokkasho, which indicated the inflow of ^239+240Pu from the catchment area in addition to direct deposition on the lake surfaces. The ¹³⁷Cs inventory in sediments of the brackish lakes was lower than that in the soil, which showed that part of the ¹³⁷Cs was removed from the sediments by the brackish water or that it was not deposited into the sediments, because of the high solubility of Cs in brackish water. The ¹³⁷Cs inventory in sediments of the freshwater lakes was higher than that of the brackish lakes, and comparable with that in soil except for one core sample out of four. The ^239+240Pu/¹³⁷Cs ratio in freshwater lake sediments was higher than that in soil, and that indicated that part of the ¹³⁷Cs was lost from the sediments. The low inventory of ¹³⁷Cs may be attributable to competition for absorption sites in sediments with ammonium ions formed in the reducing environment which occurs from summer to fall in the sediments. Those data will be used as background data on the artificial radionuclides in the lakes to assess the effect of released radionuclides on their concentrations.     

Does human activity impact the natural antibiotic resistance background? Abundance of antibiotic resistance genes in 21 Swiss lakes

Antibiotic resistance genes (ARGs) are emerging environmental contaminants, known to be continuously discharged into the aquatic environment via human and animal waste. Freshwater aquatic environments represent potential reservoirs for ARG and potentially allow sewage-derived ARG to persist and spread in the environment. This may create increased opportunities for an eventual contact with, and gene transfer to, human and animal pathogens via the food chain or drinking water. However, assessment of this risk requires a better understanding of the level and variability of the natural resistance background and the extent of the human impact. We have analyzed water samples from 21 Swiss lakes, taken at sampling points that were not under the direct influence of local contamination sources and analyzed the relative abundance of ARG using quantitative real-time PCR. Copy numbers of genes mediating resistance to three different broad-spectrum antibiotic classes (sulfonamides: sul1, sul2, tetracyclines: tet(B), tet(M), tet(W) and fluoroquinolones: qnrA) were normalized to copy numbers of bacterial 16S rRNA genes. We used multiple linear regression to assess if ARG abundance is related to human activities in the catchment, microbial community composition and the eutrophication status of the lakes. Sul genes were detected in all sampled lakes, whereas only four lakes contained quantifiable numbers of tet genes, and qnrA remained below detection in all lakes. Our data indicate higher abundance of sul1 in lakes with increasing number and capacity of wastewater treatment plants (WWTPs) in the catchment. sul2 abundance was rather related to long water residence times and eutrophication status. Our study demonstrates the potential of freshwater lakes to preserve antibiotic resistance genes, and provides a reference for ARG abundance from lake systems with low human impact as a baseline for assessing ARG contamination in lake water.     

Water quality of reclaimed water from treated urban wastewater in Chaobai River Basin,North China

The utilization of reclaimed water could be an efficient tool to alleviate water scarcity, especially for dry river augmentation. However, it is crucial to monitor water quality to ensure safety to human health and to avoid negative effects on the environment. Reclaimed water samples were collected bimonthly from May to November in 2010 in Chaobai River, and the physiochemical parameters were determined. The main results are as follows: The parameters exceeding the threshold value of the water guidelines are mainly nutrition related to nitrogen and phosphorus, which are known to increase the risk of eutrophication in surface waters. Additionally, nitrite and nitrate can be detrimental to human health. The majority of the parameters have a peaking concentration in May, whereas others either show significant temporal variation over the entire period or remain relatively constant in all four months. Correlation analysis shows that some parameters (pH, T and B) have no significant correlation with others, whereas significant positive correlation was found for Sr with EC and TDS, for Cl with TDS, for SiO₂ with TP and for NO₃–N with TN and a significant negative correlation between SO₄ and Ba. According to principal component analysis, 60.108% of the total data is represented by dominant solutes, and the second principal component with a percentage of 31.876 comprises parameters related to nitrogen. Subsequent cluster analysis of parameters identified four groups, which represent different compositions, and samples in May differ from others.     

Specific Structural Features of Zooplankton in Lakes Differing in Trophic Status: Species Populations

The index of cenotic significance and other indices calculated on its basis were used for revealing specific structural features of zooplanktonic communities in lakes differing in productivity. The results showed that new indices (complexity coefficient, index of cenotic significance of dominant species, and integrated cenotic significance of the zooplankton) strongly correlate with the trophic status of the water body and are more responsive to changes in the structure of the community than the Shannon–Weaver index of species diversity. The results confirm the hypothesis that the structure of zooplankton is simplified in the course of lake eutrophication.     

Ra–Po–Pb isotope systematics in waters of Sambhar Salt Lake,Rajasthan (India): geochemical characterization and particulate reactivity

The Sambhar Salt Lake hydrological system, including river waters, groundwaters, evaporating pans and sub-surface brines, has been analyzed for the salt content (TDS) and naturally occurring radionuclides (²¹⁰Po, ²¹⁰Pb and ^226,228Ra). The abundance of these radionuclides and their activity ratios show a wide variation in different hydrological regimes, which helps to geochemically characterize the lake system. A significantly lower Ra to total dissolved solids (TDS) ratio in the brines (by two to three orders of magnitude), when compared to the groundwaters and river waters, suggests removal of dissolved Ra by co-precipitation with Ca–Mg minerals at an early stage of the brine evolution. The concentration of Ra in evaporating lake/pan waters saturates at a value of about 35 Bq L⁻¹ over the salinity range of 100–370 g L⁻¹; attributable to its equilibration with the clay minerals. The two distinct regimes, saline lake system (lake water, evaporating pans and sub-surface brines) and groundwaters have been identified based on their differences in the distribution of ^226,228Ra isotopes. This observation points to the conclusion that the groundwaters and the lake brines are not intimately coupled in terms of their origin and evolution. The abundances of ²¹⁰Po and ²¹⁰Pb along with their activity ratios (²¹⁰Po/²¹⁰Pb) are markedly different among the surface lake waters/evaporating pans, sub-surface lake brines and groundwaters. These differences are explained in terms of different geochemical behaviour of these nuclides in presence of algae and organic matter present in these water regimes.     

Short- and long-term patterns of ¹³⁷Cs in fish and other aquatic organisms of small forest lakes in southern Finland since the Chernobyl accident

We summarize the patterns of ¹³⁷Cs activity concentrations and transfer into fish and other biota in four small forest lakes in southern Finland during a twenty-year period following the Chernobyl accident in April 1986. The results from summer 1986 showed fastest accumulation of ¹³⁷Cs into planktivorous fishes, i.e. along the shortest food chains. Since 1987, the highest annual mean values of ¹³⁷Cs have been recorded in fish occupying the highest trophic levels, for perch (Perca fluviatilis) 13,600 Bq/kg (ww) and for pike (Esox lucius) 20,700 Bq/kg (ww). At the same time, activity concentrations of ¹³⁷Cs in crustacean zooplankton and Asellus aquaticus have ranged between 1000 and 19,500 Bq/kg (dw). In 2006, 5-28% of the 1987 ¹³⁷Cs activity concentration levels were still present in perch and pike. Since 1989 their ¹³⁷Cs activity concentrations in oligohumic seepage lakes have remained significantly higher than in polyhumic drainage lakes due to the increased transfer of ¹³⁷Cs into fish in the seepage lakes with lower electrolyte concentrations, longer water retention times and lower sedimentation rate.     

Composition and Some Ecological Features of Winter Zooplankton in Deep Stratified Lakes

For the first time, zooplankton and environmental factors have been studied in winter in the deep stratified lakes Siverskoe, Borodaevskoe, and Vydogoshch. The zooplankton consists of 18–22 species of rotifers, copepods, and cladocerans, including 15–18 specifically winter, cryophilic and eurythermic forms. The populations of zooplankters reproduce actively: males and egg-bearing females (in copepods), females with embryos and eggs in brood pouches (in cladocerans), and females with attached eggs (in rotifers) are present. In lakes Siverskoe and Borodaevskoe (depth 20–24 m), where oxygen deficiency is observed only in the bottom water layer, the zooplankton populates the greater part of the water column and forms a large aggregation in the oxycline and near the bottom. The abundance of bacteria in these zones is high (up to 4–6 × 10⁶ cells/ml). In Lake Vydogoshch (depth 16 m), oxygen deficiency extends to the middle layers, and all zooplankton is distributed above the oxycline. The biomass of winter zooplankton in Lake Siverskoe in 1983 averaged 1.26 g/m³, with a maximum of 4 g/m³; in 1993, 1.4 and 8.04 g/m²; the respective values in Lake Borodaevskoe were 0.98 and 3.1 in 1983 and 0.14 and 1.6 in 1993; in Lake Vydogoshch, 0.15 and 0.24 in 1983 and 1.25 g/m³ in 1993. The development of winter zooplankton is limited by the size of the zone of oxygen deficiency and depends on the amount of food (bacterioplankton). The distribution of zooplankton in the water column and its biomass in individual layers is determined by the rate of methane formation and oxidation.__________Translated from Ekologiya, No. 3, 2005, pp. 201–214.Original Russian Text Copyright © 2005 by Rivier.     

Effect of liming on the behaviour of (90)Sr and (137)Cs in a lake ecosystem

Liming of lakes is considered one possible remedial action to reduce the accumulation of radionuclides into fish in the case of a radiological accident. These responses were tested in field conditions in a small acidified lake that was divided into two parts: one limed with CaCO₃ and the other half left as an unlimed control. The transfer of ⁹⁰Sr from water into fish decreased on average by 50% during the first year after liming. However, at the same time the ⁹⁰Sr concentration in water increased, reaching a maximum within 6 months after liming. Approximately 50% more ⁹⁰Sr was detected in water in the limed part of the lake than on control side during the first year. ⁹⁰Sr was most probably released from the sediment as the Ca concentration and pH of the water increased. As a result of these two processes, which counterbalanced each other (increased release of ⁹⁰Sr into water from sediment and decreased transfer of ⁹⁰Sr from water into fish), the ⁹⁰Sr concentration in fish did not notably differ between the limed and control sides of the lake. Liming may only be suitable as a remedial action if carried out immediately after a radiological accident, before significant amounts of radionuclides have been deposited in lake sediments. In the case of ¹³⁷Cs, the effect of liming was less pronounced. ¹³⁷Cs activity concentration in water increased in the first year by 20% and uptake by fish decreased by 20%.     

1990~2015年青海省湖泊时空变化及其对气候变化的响应分析

湖泊作为陆地水圈重要组成部分，是揭示全球气候变化与区域响应的重要信息载体。利用遥感技术获取青海省1990~2015年湖泊时空变化特征，并结合近25 a青海省气温和降雨量的时空变化特征以探究湖泊对气候的响应。结果表明:近25 a，青海省湖泊面积从12 757 km2增加到15 167 km2，湖泊数量由241个增加到286个。不同区域湖泊时空变化存在差异，主要包括3个区域：东部地区（Ⅰ）、西北地区（Ⅱ）和西南地区（Ⅲ）。其中，降雨量的增加促进了Ⅰ区域湖泊面积和数量的增加，湖泊面积由7 173 km2增加到8 474 km2，湖泊数量增加19个。Ⅱ区域湖泊面积由1 369 km2增加到1 542 km2，湖泊数量增加7个。该区域主要地形为柴达木盆地，是我国干旱区之一，干燥少雨，湖泊面积较少且变化剧烈。其湖泊扩张主要是因为降雨量增加，而较强的蒸散发极易导致湖泊萎缩。Ⅲ区域湖泊面积由4 215 km2增加到5 152 km2，湖泊数量增加19个。湖泊扩张的主要原因为降雨量的增加和蒸发的减少。研究为青海省湖泊科学利用与水资源合理配置提供了基础数据。 关键词： 青海省；湖泊；时空变化；气候变化响应     

Proposal for new best estimates for the soil solid–liquid distribution coefficient and soil-to-plant transfer of nickel

The objective of this study was to compile data, based on an extensive literature survey, for the soil solid–liquid distribution coefficient (K_d) and soil-to-plant transfer factor (TF) for nickel. The K_d best estimates were calculated for soils grouped according to texture and organic matter content (sand, loam, clay and organic) and soil cofactors affecting soil–nickel interaction, such as pH, organic matter, and clay content. Variability in K_d was better explained by pH than by soil texture.     

Using diatoms to assess the impacts of prehistoric, pre-industrial and modern land-use on Danish lakes

The impact of contemporary agriculture on Danish lakes is acknowledged to be extreme. In particular, high loading of nutrients from agricultural soils contributes to the eutrophic conditions found in many of Denmark’s lakes. Palaeolimnological studies have shown that human disturbance of the Danish landscape since the introduction of agriculture around 6,000 years ago has had a major impact on lake ecosystems. The European Union’s Water Framework Directive requires an evaluation of reference conditions for lakes, the conditions expected with only minimal human impact. Monitoring data and palaeolimnological studies of Danish lakes demonstrate that many of the most detrimental effects of eutrophication have been experienced in recent decades. A new study has suggested that the reference status for Danish lakes may be set to the status in ad 1850–1900, probably providing attainable, realistic restoration targets for many sites. The aims of this study were to explore the impacts of past and contemporary land-use on Danish lakes, and to consider how appropriate the use of 1850 as a date to define reference status is for these sites. Catchment land-cover data for ad 1800, taken from historical maps, and sedimentary diatom assemblages of the same age, from dated sediment cores, were used to assess the impact of pre-industrial land-use on 20 Danish lakes. Analysis of contemporary land-cover data and surface-sediment diatom assemblages for the 20 sites was also made. In-lake total phosphorus (TP) concentrations were estimated using the sedimentary diatom assemblages and an existing calibration dataset for Danish lakes. The percentage of the lake catchment that was agricultural land in ad 1800 explained 8.8% of the total variation in the diatom data. The land-cover variables ‘built-up areas’ and ‘plantations’, together explained 16.9% of the variation in the diatom data for the modern samples. Diatom-inferred TP concentrations were high for both ad 1800 (mean 112 μg TP L⁻¹) and the present (mean 122 μg TP L⁻¹), the latter estimates reflecting efforts in recent decades to reduce nutrient loading to Danish lakes following very high levels of nutrient enrichment post-1950. The data presented highlight the impact that human activities 200 years ago, particularly agriculture, had on Danish lake systems. The long cultural history and major anthropogenic disturbance of the Danish landscape mean that true reference conditions for lakes (or ‘baseline’ conditions, those found prior to human impacts) can be found only by considering century to millennial timescales.     

Effects of drought stress on leaf gas exchange and chlorophyll fluorescence of Glycyrrhiza uralensis

Leaf gas exchange and chlorophyll fluorescence of Glycyrrhiza uralensis Fisch at two water supplies (equivalent to 240 mm for present precipitation and to 120 mm for future decreasing precipitation) were compared. There was a midday depression in net photosynthetic rate (P _N) for either treatment, but stomatal limitation was dominant for present precipitation treatment and non-stomatal limitation for the drought treatment. Compared with present precipitation treatment, P _N, stomatal conductance (g _s) and transpiration rate (E) were always lower at drought stress, but stomatal limitation value (L _s) and water use efficiency (WUE) were higher in the morning. The decrease in carboxylation efficiency (CE), apparent quantum yield (AQY), light-saturated photosynthetic rate and maximal photochemical efficiency of photosystem 2 (PS 2) (F _v/F _m) suggested that rubisco activity reduced and PS 2 partially inactivated during the day under drought. However, part of this inactivation of PS 2 might be alleviated due to increased thermal dissipation under drought.     

Transfer of Sr into fish in Finnish lakes

The long-term behavior of ⁹⁰Sr was investigated from 1987 to 1997 in fifteen lakes in southern and central Finland following the 1986 Chernobyl accident. Both water and fish samples (perch, pike, vendace) were analyzed. ⁹⁰Sr stays long in the freshwater ecosystem; the observed half-lives during the study period were generally around 10 years in water and even longer in fish. One lake exhibited very different behavior for ⁹⁰Sr, with elevated levels in fish and water and very short observed half-life in fish, less than 2 years. Concentration factors of ⁹⁰Sr in fish (Bqkg⁻¹ f.w. in fish/Bqkg⁻¹ in water) among the studied lakes significantly correlated with both the Ca concentration and electrical conductivity of the water. More ⁹⁰Sr was transferred into fish in lakes with a low electrical conductivity and a low Ca concentration. Among other water parameters evaluated were pH, color, total nitrogen, and phosphorus.     

Specific features of the biology of Artemia in lakes of the Urals and Western Siberia

Morphometric analysis of 24 populations of Artemia brine shrimps from lakes of Western Siberia and the Urals was performed during the growing season of 2010. Differentiation among these populations was revealed, with the level of total water mineralization being the main differentiating factor. Fluctuating asymmetry in the number of setae on the right and left branches of the furca was observed in the brine shrimps. Its level showed a tendency to decrease with an increase in total water mineralization in the lakes.     

运用MODIS数据反演洪湖叶绿素a含量业务可行性分析

洪湖是湖北省最大的湖泊，具有调蓄、灌溉、供水、渔业、物种保护、航运、旅游等多种功能，是长江中下游典型的大型浅水型湖泊。传统的设点监测费力、费时，随着遥感技术和手段的进步，遥感反演洪湖叶绿素a浓度成为技术上可能。利用2005年至2010年6年监测数据与同期MODIS数据进行统计分析，研究业务上进行洪湖叶绿素a含量反演的可能性，结果表明：当叶绿素a含量比较高时，它成为影响湖中NDVI指数的主要因素，当浓度较低时，它与NDVI指数相关性差，表明它不是主要要素；通过分析不同时段两者统计关系结果为：12～2月因藻类浓度比较小，叶绿素a浓度低，加上其它要素干扰湖中NDVI指数，监测数据与同期MODIS数据中NDVI指数相关性比较低（也是极显著相关），其它时间都有较好的相关性（相关系数都高于085），研究表明：运用MODIS数据中的NDVI指数能准确监测洪湖叶绿素a含量。并提出相应的业务处理流程与方法     

Differential exposure of alpine ospreys to mercury: Melting glaciers,hydrology or deposition patterns?

Mercury (Hg) is a global contaminant impacting even remote environments. In alpine watersheds, glacial meltwater is a source of Hg, which accumulated in glaciers during the 1960–1980 cooling cycle. The considerable variation observed for Hg exposure of alpine animals in proximal watersheds could result from differences among those watersheds in Hg loading from glacial meltwater. Alternatively, variation may be the result of hydrology, atmospheric Hg deposition patterns, or food web characteristics. To examine those possibilities, we measured Hg in ospreys (Pandion haliaetus), apex predators in 15 watersheds in western Canada. Mercury levels in feathers of nestlings increased with increasing modeled atmospheric deposition rates and decreased with lake size. In eggs mercury decreased with δ¹³C, an indicator of food web structure, and with pH and elevation. Thus, Hg levels in chicks were strongly associated with local patterns relevant when the chicks were growing (e.g. the period post-snow melt: Hg deposition, lake size) while Hg levels in eggs were weakly associated with local patterns relevant during the snow melt (elevation, δ¹³C), with the remainder of the Hg variation in eggs determined by other factors such as possible Hg accumulation by the adult elsewhere. Modeled atmospheric deposition from prevailing upwind locations including Asia, followed by runoff into small lakes, were related to Hg patterns in osprey, with little apparent role for recent melting of glaciers. Our study highlights the importance of physical patterns to the environmental chemistry of top predators.     

The impact of warming on the appearance of furunculosis in fish of the James Bay region,Quebec, Canada

A regional climate change impact assessment was conducted which investigated the timing of the first appearance of furunculosis caused by the bacterium, Aeromonas salmonicida, in fish of the Ouje-Bougoumou region of northern Quebec, Canada. Historical data were used to assess whether there was a temporal relationship between increased temperatures (observed climate data) and the appearance of furunculosis (traditional environmental knowledge was used to provide context). To project future impacts of climate change, climate models and lake models were used. Regression analysis revealed a significant, positive temporal trend in mean air temperature. The temperature range conducive to A. salmoncida survival coincided with the first appearance of furunculosis. In addition, it is predicted that lake temperatures will remain suitable for the presence of A. salmonicida into the future; it is likely that the disease will persist throughout the twenty-first century. Climate change appears to be a factor explaining the onset of furunculosis; however, other factors/stressors cannot be discounted, such as, the effects past mining activities near the lakes of the Ouje-Bougoumou region have had on the body burden of contaminants in the fish (and the potential effects on the fish immune system).