Recovery of acid-sensitive species of ephemeroptera, plecoptera and trichoptera in river audna after liming

River Audna has been continuously limed on a full scale basis since 1985. Monitoring of benthic invertebrates of the river showed that the fauna was dominated by acid-tolerant species before liming and during the first year after the start of the treatment. Moderately acid-sensitive species, like Diura nanseni, Isoperla grammatica and Hydropsyche siltalia were found only in small numbers in a few localities in this period. In autumn 1987, the first appearance of the highly acid-sensitive mayfly Baetis rhodani was recorded at two stations in the main river. During the following years, this species colonized other localities and several other sensitive invertebrates, such as Heptagenia sulphurea, Caenis horaria, Hydropsyche pellucidula and Lepidostoma hirtum were also recorded. The change in faunal composition was highly significant compared to unlimed reference stations.     

The response of stream-dwelling fish to liming

The fish fauna in 22 limed and seven unlimed small streams was monitored using yearly electrofishing to assess the effects of liming on species occurrence and abundance. The liming techniques were divided into three main methods, lake liming, doser liming and wetland liming, to evaluate whether different strategies had different effects on the fish fauna. The predominant species at the investigated stations were salmonids, mainly brown trout (Salmo trutta) and Atlantic salmon (Salmo salar). Other species generally occurred in low numbers. The average number of fish species did not increase significantly after liming, which was probably due to recolonization difficulties caused by the frequent occurrence of migration obstacles in the streams. After liming the density of salmonids increased significantly, irrespective of the liming method. Other fish species showed no general increase, but in individual streams significant increases of European minnow (Phoxinus phoxinus) and bullhead (Cottus gobio) occurred. Some unlimed streams had acid spates with a pH below 6, which immediately lowered the numbers of salmonid parr. Other unlimed streams lost fish species progressively due to increasing acidification. pH, and probably increased levels of metals, were the major factors regulating the fish fauna. Few examples of biotic interactions were observed, but with an increase of Atlantic salmon parr after liming, brown trout abundances decreased in three streams.     

The effect of liming agricultural land on the chemistry and biology of the River Esk, north-west England

A land-use study indicated that a reduction in agricultural liming may have been a major factor in the development of acid episodes and consequent fish kills in the River Esk and River Duddon. A field study was carried out to determine whether the reintroduction of catchment liming in the Esk valley could ameliorate acid episodes and thus prevent fish kills. Lime was applied to areas which had been limed in the past, comprising 10% of the Esk catchment. Flow, pH, calcium, aluminium, total humic substances, conductivity and invertebrates were monitored before and after liming. The River Duddon was monitored as a reference. There was a general reduction of the acidity of both the River Esk and the River Duddon during the study period. This appeared to be controlled by rainwater chemistry. There was little evidence for a major effect of liming on water chemistry which suggests that the mortalities of salmonids in the early 1980s were not due to a reduction in agricultural liming.     

The mixing zone between limed and acidic river waters: complex aluminium chemistry and extreme toxicity for salmonids

When liming running waters, dosers must compensate for different flow and water qualities and for the downstream inflow from acid tributaries which creates mixing zones. At a certain point in the mixing zone, a constant or fluctuating chemical disequilibrium will appear due to transformation processes. In laboratory assays, over-saturated solutions of aluminium with ongoing active precipitation of aluminium have been found to be especially toxic to fish. Recent experiments in a mixing zone in the limed River Audna, Norway, have confirmed this phenomenon. Atlantic salmon (Salmo salar L.) and sea trout (Salmo trutta L.) smolts were exposed to acid and limed waters and mixtures of the two waters downstream from the point of connection. In the acid tributary (mean values: pH=4.8, Ca=1.3 mg litre (-1)), Ali 236 microg litre(-1)=), LT5) was 22 and 40 h for Atlantic salmon and sea trout, respectively. In the mixing zone (pH=4.8-6.5, Ca=1.2-3.2 mg litre(-1), Ali=50-240 microg litre(-1)), LT50 was 7 h for both species, masking the normal species difference in tolerance. Osmoregulatory failure and rapid gill lesions occurred in the mixing zone as an effect of the transformation of Al into high molecular weight precipitating species. This is the first documentation of the existence of such highly toxic mixing zones in nature, and the results clearly show that the mixing zone is even more toxic to fish than acid aluminium-rich waters.     

Evaluation of biological integrity of a small urban stream system by investigating longitudinal variability of the fish assemblage

We investigated the integrity of fish assemblages of a small anthropogenically impacted urban stream system in south-western Germany. Heavy point and non-point pollution physiologically stresses the aquatic fauna while migration barriers and river morphological alterations negatively influence habitat availability. Investigations conducted in 1998 and 1999 revealed that the fish assemblage was altered and several site-specific fish species were missing while non-site-specific species were relatively common. Highest species diversity was recorded in a reach downstream of the main migration barrier, while upstream only a few species were present. In general, a shift to ubiquitous and limnophilic species as well as to less pollution sensitive species was observed. Adult fish dominated the population structure throughout the stream course. Recruitment was confined mainly to the less polluted headwater. In the present study we introduce an assessment system based on the similarity of the potential natural and the actually established fish assemblage as demanded by the Water Framework Directive of the European Union for the evaluation of the ecological status of a fish assemblage in a stream [EC of the European Parliament and of the Council of Europe establishing a framework for community action in the field of water policy. Brussels, 30 June, 2000. 1997/0067 (COD)]. Both, stream morphological quality and pollution data sampled within the two study years confirm the validity of the suggested assessment method.     

Case study on rehabilitation of a polluted urban water body in Yangtze River Basin

In the past three decades, the fast development of economy and urbanization has caused increasingly severe pollutions of urban water bodies in China. Consequently, eutrophication and deterioration of aquatic ecosystem, which is especially significant for aquatic vegetation, inevitably became a pervasive problem across the Yangtze River Basin. To rehabilitate the degraded urban water bodies, vegetation replanting is an important issue to improve water quality and to rehabilitate ecosystem. As a case study, a representative polluted urban river, Nanfeihe River, in Hefei City, Anhui Province, was chosen to be a rehabilitation target. In October 2009 and May 2010, 13 species of indigenous and prevalent macrophytes, including seven species emergent, one species floating leaved, and five species submersed macrophytes, were planted along the bank slopes and in the river. Through 1.5 years’ replanting practice, the water quality and biodiversity of the river had been improved. The concentrations of total nitrogen (TN), total phosphorus (TP), and ammonia nitrogen (NH₄ ⁺–N) declined by 46.0, 39.5, and 60.4 %, respectively. The species of macrophytes increased from 14 to 60, and the biodiversity of phytoplankton rose significantly in the river (p?<?0.05). The biomasses of zooplankton and benthos were also improved after the vegetation replanting. The study confirmed that vegetation replanting could alleviate the increasing water pollution and rehabilitate the degraded aquatic ecosystem. The case study would be an example for polluted urban waters restoration in the middle–downstream area of Yangtze River Base.     

Evaluating the fish safety level of river water and wastewater with a larval medaka assay

A larval medaka (Oryzias latipes) assay was proposed to evaluate the fish safety level of river waters and wastewaters. Organic toxicants were 10-100 times concentrated with adsorption cartridges from 4 l of river water or 1-10 times concentrated from 400 ml of wastewater. Toxicity of these concentrated solutions was determined by exposing 48-72 h post-hatch age larvae for 48 h. The method effectively revealed a variation of the median lethal concentration ratio (LCR50) from 13 to >100 in 125 river water samples, and from <1 to >10 in five typical wastewater samples. Ayase River, which takes water mostly from agricultural or household discharge, showed significantly (P<0.001) lower LCR50 than Sagami River that takes natural water as the source. Safety Levels in both Sagami River and Ayase River were influenced by the irrigation activity, LCR50 at some sites showing a seasonal-specific decrease in winter. Pollution from pulp and paper industries contributed to the low LCR50 in several tributaries of Ayase River. Required little manpower in sampling, pretreatment and testing, the proposed larval medaka assay was proved as an efficient tool for screening those high risk sites for priority management.     

Pesticide and PCB levels in fish from Alberta (Canada)

Pesticide and PCB analyses were completed on fat and muscle samples of 750 fish collected from 11 major lakes and rivers in Alberta. Although phenoxy and organophosphate residues were always below detectable limits, traces of chlorinated pesticides and their derivatives, particularly DDE, DDD and chlordane, were detected in most fat samples. Methoxychlor was frequently found in goldeye from the North Saskatchewan River but not recorded in fish from any other lake or river. Its presence in goldeye, a highly migratory species, was probably a result of biting-fly control programs in the Saskatchewan part of the river. PCB levels exceeded 25 mg/kg in the fat of several species from the North Saskatchewan River but were generally lower in the other systems. Analysis of 160 sediment samples from the North Saskatchewan River revealed no point source of PCB contamination, with residues always <0.01 mg/kg dry weight.     

综合调水对苏州河周边水系水质影响的数值模拟

进行长期有效的水资源综合调度是实现2010年苏州河河水变清的综合整治目标的一项重要措施。为进一步论证该项措施对周边水系的水质影响,为综合调水提供科学的决策依据,利用MIKE11模型系统建立了上海市苏州河水系的水动力、水质模型,进行苏州河综合调水对黄浦江以及蕴藻浜水质的影响作用的数值模拟。分析表明,苏州河综合调水对松浦大桥取水口水质基本没有影响,并可以在一定程度上改善黄浦江干流中下游河段的水质;东引北排初期会增加蕴藻浜干流的污染负荷,持续调水6d后蕴藻浜干流河段的水质将得到改善。     

Effects of subacute doses of cadmium on pH-stressed Leptophlebia marginata (L.) and Baetis rhodani Pictet (Insecta: Ephemeroptera)

Cd uptake, emergence, survival and locomotory activity at two pH levels were studied in a 27-day experiment with Leptophlebia marginata and in a 19-day experiment with Baetis rhodani. Model ecosystems containing recirculating stream water, patches of sediment and leaves, simulated a natural stream. During the experiments, concentrations of Al, Cd, Fe and Zn increased in the water at pH 5, while conductivity decreased. Cd was taken up by both species at a rate which indicated linear uptake kinetics. No steady state of Cd in the animals was observed. The larvae of B. rhodani contained significantly more Cd than the adults (p<0.001). Uptake of Cd by Baetis rhodani was higher at pH 7 than at pH 5 (p<0.05). The survivial of L. marginata was not influenced by pH and Cd stress, but emergence was significantly reduced (p<0.05). The survival and the emergence of B. rhodani were reduced by low pH and also by Cd addition (p<0.01). At pH 7, Cd had no significant adverse effect on survival. Locomotory activity of Baetis rhodani was reduced by low pH and additionally by Cd stress.     

Derivation of site-specific surface water quality criteria for the protection of aquatic ecosystems near a Korean military training facility

This study suggested the first Korean site-specific ecological surface water quality criteria for the protection of ecosystems near an artillery range at a Korean military training facility. Surface water quality (SWQ) criteria in Korea address human health protection but do not encompass ecological criteria such as limits for metals and explosives. The first objective of this study was to derive site-specific SWQ criteria for the protection of aquatic ecosystems in Hantan River, Korea. The second objective was to establish discharge criteria for the artillery range to protect the aquatic ecosystems of Hantan River. In this study, we first identified aquatic organisms living in the Hantan River, including fishes, reptiles, invertebrates, phytoplankton, zooplankton, and amphibians. Second, we collected ecotoxicity data for these aquatic organisms and constructed an ecotoxicity database for Cd, Cu, Zn, TNT, and RDX. This study determined the ecological maximum permissible concentrations for metals and explosives based on the ecotoxicity database and suggested ecological surface water quality criteria for the Hantan River by considering analytical detection limits. Discharge limit criteria for the shooting range were determined based on the ecological surface water quality criteria suggested for Hantan River with further consideration of the dilution of the contaminants discharged into the river.     

Restoring acidified streams in upland Wales: a modelling comparison of the chemical and biological effects of liming and reduced sulphate deposition

Increasing emphasis is being placed on the restoration of surface waters which have been affected by acidification. Amongst the possible strategies are management of the causes, by reducing acidic deposition, and management of the symptoms, by treating affected areas with basic material such as limestone. In few cases have there been comparisons of the likely effect of these two strategies on surface water chemistry and ecology, although there is widespread belief that the two are similar in outcome. At present, only a modelling approach permits such a comparison. This paper describes chemical and biological responses of three Welsh streams whose catchments were limed experimentally in 1987-1988 as part of the Llyn Brianne project. Actual changes are compared with simulated changes which occur following reduced acid deposition according to the hydrochemical model, MAGIC (Model of Acidification of Groundwaters in Catchments). The results indicate that liming and 90% reduction in sulphate deposition reduce concentrations of toxic aluminium to similar levels. However, calcium concentrations and pH were increased by liming to values which were high by comparison with conditions simulated at low acid deposition, either in the past or future. Trout density increased in two of the streams following liming to levels similar to those simulated under low acid deposition. By contrast, the aquatic invertebrate fauna changed after liming so that streams acquired species typical of higher calcium concentrations than those simulated under low acid deposition. Species characteristic of 'soft water' communities were apparently lost, although more data are required to separate treatment effects from random change in the longer term. The 'soft water' community also declined in the model as a result of acidification, indicating that both liming and acid deposition resulted in a different faunal community from that prior to acidification. The results support those who conclude that liming is suitable for the restoration or protection of a fishery, but indicate that there may be other ramifications, for example to conservation, which must be considered when liming is implemented. However, the simulation of biological conditions under low acid deposition involves extrapolation from the initial data base. Further data are now required to assess empirically the likely biological character of British streams which have low base cation concentrations unaffected by acid deposition.     

Environmental risk assessment in five rivers of Parana River basin,Southern Brazil,through biomarkers in Astyanax spp.

Environmental Science and Pollution Research - In the current study, water quality of five river sites in Parana River basin (Brazil), utilized for public water supply, was assessed through a set...     

Recovery by riffle macroinvertebrates in a river after a major accidental spillage of chlorpyrifos

The impact of a major spillage of the insecticide 'Dursban' on the riffle macroinvertebrates along 19 km of the River Roding, Essex, is described. Five affected riffles and an upstream control were kick-sampled at approximately 10-week intervals for two years following the spill, and the results are compared with species composition and relative abundance data collected from the same sites during the previous six years. Initial concentrations of the active ingredient, chlorpyrifos, in river water (up to 2.5 mg litre(-1)) exceeded the level lethal to all the aquatic arthropods present by at least 10-fold, and this group of macroinvertebrates was eliminated. Molluscs and annelids, which are relatively tolerant of chlorpyrifos, survived. Since these groups already dominated the lowermost urban reaches, the impact of the spill was greatest further upstream, where reaches with a better water quality previously supported a more diverse and abundant arthropod fauna. Chlorpyrifos residues in water declined below 1 microg litre(-1) within 11 weeks, but sediment within 5 km of the spillage site remained highly contaminated for considerably longer. Of ten arthropod taxa previously common to all sites, chironomid larvae were first to recolonise affected reaches, 13 weeks after the spill. The isopod Asellus aquaticus, was also quick to recover. Although other arthropods had recolonised most sites within 79 weeks, the coleopteran Oulimnius tuberculatus and the epheremeropteran Caenis moesta had failed to return to the lowermost reaches after 108 weeks. Downstream drift was probably the principal factor influencing the pattern of arthropod recolonisation, with the location and aquatic fauna of tributary streams entering the affected reaches being particularly important.     

Mobility of heavy metals as related to soil chemical and mineralogical characteristics of Brazilian soils

In order to better understand the relationship between soil characteristics and mobility of some heavy metals, correlation studies were conducted in samples of unlimed and limed A, B and C horizons of three Brazilian soils, representative of the majority of the tropical soils. A number of chemical and mineralogical characteristics of one Oxisol and two Ultisols were related to the retardation factors (Rf) for zinc (Zn), cadmium (Cd), copper (Cu) and lead (Pb). The retardation factors, obtained in leaching column experiments, were used as an estimate of solute movement in the profile. Soil types and soil horizons were found to influence metal retardation factors which, in turn, correlated better with the chemical than the mineralogical soil characteristics. For the unlimed soil samples, the soil characteristics that significantly correlated with Zn-Rf and Cd-Rf were the sum of exchangeable bases (SB), and soil exchangeable (Ca-KCl) and non-exchangeable (Ca-HCl) calcium contents. These results showed the strong influence of the cation exchange phenomenon on the retention and mobility of these two metals. For Cu and Pb, not only SB, cation exchange capacity (CEC) and Ca-KCl and Ca-HCl but also the organic matter correlated well with the Rf, showing that complex or chelate formation may play an important role in the movement of these elements. The important soil chemical characteristics related to the retardation factors in the limed soil samples were SB for Cd, and Ca-HCl for Cu and Pb, suggesting that precipitation may also influence the mobility and retention of the latter two heavy metals in these soil samples. Soil pH influenced the heavy metals adsorption and movement as shown by the significant correlation with the retardation factors when the combined data for the unlimed and limed soil samples was considered.     

万家寨引黄北干线桑干河道输水水质模拟与控制

主要对采用河道输水方案的山西万家寨引黄北干线桑干河道水质进行模拟与控制研究,依据各水体特性建立河流水质数值模型和水库数值模型,运用系统分解方法将整个研究河道分解为若干个河段,并采用情景分析方法生成3个水质模拟情景,分析模拟结果表明,在山阴取水口和怀仁取水口水质达地表水Ⅲ类标准条件下,册田水库的入水水质不达标。应用反演思想生成2个水质控制情景和3个子情景,在水库出水口水质达标的情况下,分析确定沿河各排污口的污染物排放控制量,给出了保证册田水库水质安全的控制方法。     

Relating cadmium concentrations in three macrophyte-associated freshwater invertebrates to those in macrophytes,water and sediments

We found that Cd concentrations in three species of macrophyte-associated invertebrates (the gastropods Bithynia tentaculata and Physa gyrina, and the amphipod Gammarus fasciatus) collected at twenty sites along the St. Lawrence River were correlated with Cd concentrations in their main food source, i.e. macrophytes and associated periphyton. Cd in these invertebrates was not significantly correlated with Cd concentrations in the sediments (even when corrections for iron oxide or organic carbon content were applied) or to calculated free-cadmium concentrations in the water. Cd levels in juveniles of B. tentaculata were very tightly linked to Cd concentrations in macrophytes, which is consistent with the close relationship that these organisms have developed with macrophytes. Linear models predicting Cd levels in juveniles of B. tentaculata from Cd levels in different macrophyte species were strong (R2 = 0.69-0.90). Analysis of covariance on these models showed no statistical difference of slope or intercept for any of the macrophyte species, except Vallisneria americana. We suggest that the macrophyte-periphyton complex is a key link in the transfer of cadmium to some aquatic invertebrates in the littoral zone of the St. Lawrence River and that macrophytes and their associated epiphytes should also be used as biomonitors.     

Dynamics of phosphorus forms in the bottom sediments and their interstitial water for the Prut River (Moldova)

Phosphorus concentration in rivers results from both external inputs and internal loading from the bottom sediments. Seasonal, spatial, and multi-annual dynamics of phosphorus forms in bottom sediments and their interstitial water for the river Prut (Moldova) were evaluated. In order to determine content of total phosphorus in the bottom sediments, fresh (wet) samples were subjected to persulfate oxidation. The content of inorganic phosphorus was determined after acidic oxidation of samples. The amount of organic phosphorus was obtained by subtracting inorganic phosphorus from the amount of total phosphorus. Content of phosphorus forms in interstitial water was determined after centrifugation of fresh (wet) sediments. In general, the shape of dynamics of the amounts of inorganic phosphorus in sediments was close during years?2009, 2010, and 2011, with registered higher contents of this form on the middle course of the river. The spatial dynamics of organic phosphorus is less homogeneous along the Prut River. During 2009, higher amounts of organic phosphorus were recorded on the middle sector. During the spring of year?2010, the content of organic phosphorus in sediments was practically not changed along the river. The ratio of inorganic/organic phosphorus in bottom sediments was similar during the researched years, with the predominance of the inorganic phosphorus being recorded. Also, the increasing tendency of the percentage of organic phosphorus from spring to summer was identified. Generally, appropriate spatial and seasonal dynamics of phosphorus forms in bottom sediments and their interstitial water were recorded, although sometimes with some differences.     

Mitigation of low stream pH and its effects on salmonids

Crushed limestone (200 tonnes) was spread in bars on the bed of an acidic brook (mean pH 5.0) in Nova Scotia, Canada. A seasonally variable but significant increase in pH of running water resulted, and a longitudinal pH gradient over the limed section extended to the mouth of the brook. The effectiveness persisted after 3 years, during which pH downstream of the limestone increased an average of 0.4 pH units (range < 0.1-1.3 pH units) along with significantly increased Ca, Mg and acid neutralizing capacity. Total and exchangeable Al were not altered by the limestone and non-exchangeable forms dominated. The interstitial water was nearly neutral (mean pH 7.1) in limestone beds but it was acidic (mean pH 5.4) in gravel beds of the control section upstream. Spawning Atlantic salmon (Salmo salar) dug three times more redds in gravel of the limed section than in the control. Salmon fry survived and they were significantly more abundant in the limed section than in the control. The density of juvenile salmon increased over time, indicating a recovery of the population. The density of brook trout (Salvelinus fontinalis) also increased and trout fry were usually more abundant in the limed section than in the control. The observed benefits for salmonids suggest that small-scale application of limestone to stream beds and spawning sites can be used to mitigate the effects of low stream pH.     

Evaluation of zoobenthic assemblages and recovery following petroleum spill in a coastal area of Río de la Plata estuarine system, South America

The objective of this work was to analyse zoobenthic assemblages in the coastal sector of the Río de La Plata, Argentina, after a petroleum spill. Sampling stations were located in representative sites of various landscapes. Structure, composition, physico-chemical parameters and seasonal changes were recorded in order to assess taxocenosis evolution during the period 1999–2003. Recovery signs were estimated by means of biotic indices and the presence of sensitive species. Tolerant species were dominant in heavily polluted sites, with low diversity and water quality values, according to the biotic indices used. In certain zones, sediment quality remains impoverished, with a visible oil film on the surface. However, during the last sampling, some points showed an increase in biotic indices, pointing to a slight improvement in environmental conditions.