Temporal and spatial changes in primary biomass as a diagnosis and prognosis in environmental impact (Rapel Reservoir,Central Chile)

Extensive mortality of silversides (Atherinidae), Odontesthes bonariensis, was recorded during July 1989 in the Rapel Reservoir. Temporal and spatial changes observed in biomass concentration (chlorophyll-a) through both ground and remote sensing samples (LANDSAT), allowed us to establish a potential environmental impact. Ground measurements established an input of sulfate (SO₄) in a eutrophic area. The mean concentration of biomass tended to decrease in this area in comparison with other mesotrophic areas. The local disfunction associated with the observed biomass changes has been used to develop a prediction in species composition and in biomass concentration.

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Resumen Durante la primera semana de Julio de 1989, se registró una muerte masiva de pejerreyes, Odontesthes bonariensis en el Embalse Rapel. En los procesos de monitoreo de la calidad de agua en el Embalse Rapel, se utilizó una representacion espacial primaria de las variables de estado elegidas. Las tendencias témporo-espaciales observadas en la concentración de biomasa fitoplanctónica (clorofila-a) permitieron establecer un impacto ambiental potencial por un agente exógeno al sistema. A partir de mediciones de terreno se estableció la presencia de sulfato (SO₄) en una zona de características eutróficas. Los efectos observados en esta zona, en comparación al resto del embalse, fueron una disminución en la concentración media de la biomasa. La disfunción local observada, permitió sustentar una prognosis asociada a la composición de especies fitoplanctónicas y la concentración de biomasa local.

     

Using Landsat image time series to study a small water body in Northern Spain

Ramsar Convention and EU Water Framework Directive are two international agreements focused on the conservation and achievement of good ecological and chemical status of wetlands. Wetlands are important ecosystems holding many plant and animal communities. Their environmental status can be characterised by the quality of their water bodies. Water quality can be assessed from biophysical parameters (such as Chlorophyll-a concentration ([Chla]), water surface temperature and transparency) in the deeper or lacustrine zone, or from bioindicators (as submerged aquatic vegetation) in the shallow or palustrine zone. This paper proves the use of Landsat time series to measure the evolution of water quality parameters and the environmental dynamics of a small water body (6.57 ha) in a Ramsar wetland (Arreo Lake in the North of Spain). Our results show that Landsat TM images can be used to describe periodic behaviours such as the water surface temperature or the phenologic state of the submerged vegetation (through normalized difference vegetation index, NDVI) and thus detect anomalous events. We also show how [Chla] and transparency can be measured in the lacustrine zone using Landsat TM images and an algorithm adjusted for mesotrophic Spanish lakes, and the resulting values vary in time in accordance with field measurements (although these were not synchronous with the images). The availability of this algorithm also highlights anomalies in the field data series that are found to be related with the concentration of suspended matter. All this potential of Landsat imagery to monitor small water bodies in wetlands can be used for hindcasting of past evolution of these wetlands (dating back to 1970s) and will be also useful in the future thanks to the Landsat continuity mission and the Operational Land Imager.     

The Duero Diatom Index (DDI) for river water quality assessment in NW Spain: design and validation

Diatom indices developed in certain geographic regions are frequently used elsewhere, despite the strong evidence that such metrics are less useful when applied in regions other than that where species–environment relationships were originally assessed, showing that species have particular autoecological requirements in different geographic areas. The goal of this study was to develop a new metric, the Duero Diatom Index (DDI), aimed at monitoring water quality in Duero basin watercourses (NW Spain). In summer 2008 and 2009, a total of 355 epilithic diatom samples were collected following standard protocols. The 2008 samples were used to develop the DDI, whereas the samples collected during 2009 were used in the index testing. Weighted averages method was used to derive the autoecological profiles of diatoms with respect to pH, conductivity, biological oxygen demand, ammonia, nitrates, and phosphates. The optimum and tolerance values for the measured environmental variables were determined for 137 taxa with abundances and frequencies of occurrence above 1 %, and subsequent trophic indicator and sensitivity values were defined for the DDI. The correlation between the observed and the diatom-inferred nutrient concentrations was highest for phosphates (ρ _S?=?0.72). Significant statistical relationship were observed between DDI values and the chemistry-based General Quality Index values (p?=?0.006) and the specific pollution index (SPI) diatom metric (p?=?0.04). DDI has demonstrated a better correlation with water chemistry than SPI diatom metric.     

Dissolved oxygen content as an index of water quality in San Vicente Bay,Chile (36 degrees 45'S)

The present report describes some effects of industrial and municipal effluents on the waters of San Vicente Bay. Analyses ofthe main substances contained in the fishing industry effluentsuggest rating criteria based on the oxygen saturation of thewater as an assessment of organic pollution. Six cruises were carried out throughout the Bay, from June to December 1996. Watersamples were analyzed for dissolved oxygen, oil and grease content, and sediment samples for organic matter content. Waterparameters (salinity, temperature) were used to characterize theBay's hydrography, and to calculate values for oxygen saturation. The measurements demonstrated a local broad range of oxygen deficit, with a maximum of 45% in the winter to 95% in the spring. In November more than 65% of the Bay's area showed oxygendeficits greater than 40%. Organic matter was unusually high insediments along the northern sector of the Bay. The results suggest that the oxygen depletion was a representative parameterfor establishing a relative scale of water quality in this Bay.     

Sources and seasonal variation of PAHs in the sediments of drinking water reservoirs in Hong Kong and the Dongjiang River (China)

The main objective of this study was to investigate occurrence of polycyclic aromatic hydrocarbons (PAHs) in the sources of the drinking water supply of Hong Kong. The main emphasis was on the Dongjiang River in mainland China which is the major source, supplying 80% of the total consumption in Hong Kong (the remaining 20% is obtained from rain water). Sediments were collected from four sites along the Dongjiang River and four reservoirs in Hong Kong during both the dry and wet weather seasons. The concentrations of total PAHs in the sediments ranged between 36 and 539 microg/kg dry wt. The lower levels were detected at the upstream site on the Dongjiang River and at the reservoirs in Hong Kong (44-85 microg/kg dry wt), while the mid- and downstream sites on the Dongjiang River were more polluted (588-658 microg/kg dry wt). Examination of the PAH profiles revealed that the mid- and downstream sections of the Dongjiang River contained high percentages of 4,5,6-ring PAHs, similar to the amounts of atmospheric particulate matter and road dust collected during the dry weather season from the Pearl River Delta region as reported in the literature. Seasonal changes were revealed in the reservoirs of Hong Kong, with higher PAH levels in the wet weather season than in the dry weather season. For those reservoirs in Hong Kong that store water from the Dongjiang River, a distinct seasonal pattern was also observed, namely, that under dry weather season conditions the PAHs found in the sediments were primarily from petrogenic source, while under wet weather season conditions they were from pyrolytic sources. No such pattern was detected in the reservoirs which stored only rain water.     

Survey design for lakes and reservoirs in the United States to assess contaminants in fish tissue

The National Lake Fish Tissue Study (NLFTS) was the first survey of fish contamination in lakes and reservoirs in the 48 conterminous states based on a probability survey design. This study included the largest set (268) of persistent, bioaccumulative, and toxic (PBT) chemicals ever studied in predator and bottom-dwelling fish species. The U.S. Environmental Protection Agency (USEPA) implemented the study in cooperation with states, tribal nations, and other federal agencies, with field collection occurring at 500 lakes and reservoirs over a four-year period (2000–2003). The sampled lakes and reservoirs were selected using a spatially balanced unequal probability survey design from 270,761 lake objects in USEPA’s River Reach File Version 3 (RF3). The survey design selected 900 lake objects, with a reserve sample of 900, equally distributed across six lake area categories. A total of 1,001 lake objects were evaluated to identify 500 lake objects that met the study’s definition of a lake and could be accessed for sampling. Based on the 1,001 evaluated lakes, it was estimated that a target population of 147,343 (±7% with 95% confidence) lakes and reservoirs met the NLFTS definition of a lake. Of the estimated 147,343 target lakes, 47% were estimated not to be sampleable either due to landowner access denial (35%) or due to physical barriers (12%). It was estimated that a sampled population of 78,664 (±12% with 95% confidence) lakes met the NLFTS lake definition, had either predator or bottom-dwelling fish present, and could be sampled.     

Development and evaluation of the Lake Macroinvertebrate Integrity Index (LMII) for New Jersey lakes and reservoirs

In response to the recent focus by the U.S. EnvironmentalProtection Agency on bioassessment of lakes, a multimetric index was developed for New Jersey lakes and reservoirs using benthicmacroinvertebrates. Benthic samples were collected fromreference and impaired lakes with muck and intermediate sedimentsin central and northern New Jersey during summer 1997. We used astepwise process to evaluate properties of candidate metrics andselected five for the Lake Macroinvertebrate Integrity Index(LMII): Hilsenhoff Biotic Index (HBI), percent chironomidindividuals, percent collector-gatherer taxa, percentoligochaetes/leeches, and number of Diptera taxa. We scoredmetrics as the fraction of the best expected value (based on allsites) achieved at a site and summed them into the LMII. Evaluation of the LMII showed that it discriminated well betweenreference and impaired lakes and was strongly related to severalpotential stressors. Chemical and physical gradients distinguished between reference and impaired lakes, and the LMIIsummarized these gradients well. The LMII corresponded stronglywith land use, but some lakes with more urban land use stillachieved high scores. Based on a power analysis, the ability ofthe LMII to detect differences in condition was sensitive to thenumber of samples from each lake.     

Trends in nutrient and sediment retention in Great Plains reservoirs (USA)

Reservoirs are artificial ecosystems with physical, chemical, and biological transitional characteristics between rivers and lakes. Greater water retention time in reservoirs provides conditions for cycling materials inputs from upstream waters through sedimentation, biological assimilation and other biogeochemical processes. We investigated the effects of reservoirs on the water quantity and quality in the Great Plains (Kansas, USA), an area where little is known about these dominant hydrologic features. We analyzed a 30-year time-series of discharge, total phosphorus (TP), nitrate (NO₃ ^?), and total suspended solids (TSS) from six reservoirs and estimated overall removal efficiencies from upstream to downstream, testing correlations among retention, discharge, and time. In general, mean removal of TP (42–74 %), TSS (0–93 %), and NO₃ ^? (11–56 %) from upstream to downstream did not change over 30 years. TP retention was associated with TSS removal, suggesting that nutrient substantial portion of P was adsorbed to solids. Our results indicated that reservoirs had the effect of lowering variance in the water quality parameters and that these reservoirs are not getting more or less nutrient-rich over time. We found no evidence of temporal changes in the yearly mean upstream and downstream discharges. The ratio upstream/downstream discharge was analyzed because it allowed us to assess how much contribution of additional unsampled tributaries may have biased our ability to calculate retention. Nutrient and sediment removal was less affected by hydraulic residence time than expected. Our study demonstrates that reservoirs can play a role in the removal and processing of nutrient and sediments, which has repercussions when valuing their ecological services and designing watershed management plans.     

Monitoring toxic cyanobacteria and cyanotoxins (microcystins and cylindrospermopsins) in four recreational reservoirs (Khon Kaen, Thailand)

The toxic cyanobacterial communities of four recreational reservoirs (Bueng Kaen Nakhon, Bueng Thung Sang, Bueng Nong Khot, and Bueng See Than) in Amphur Muang, Khon Kaen Province, Thailand, were investigated. Water samples were collected via monthly sampling from June to October 2011 for the study on the diversity and density of toxic cyanobacteria and toxin quantification. The main toxic cyanobacteria present in these reservoirs were Aphanocapsa sp., Cylindrospermopsis sp., Leptolyngbya sp., Limnothrix sp., Microcystis sp., Oscillatoria sp., Planktolyngbya sp., Planktotrix sp., and Pseudanabaena sp. The dominant bloom-forming genera in the water samples from Bueng Nong Khot and Bueng See Than were Microcystis sp. and Cylindrospermopsis sp., respectively. Enzyme-linked immunosorbent assays specific for cyanotoxins were performed to detect and quantify microcystins and cylindrospermopsins, with the highest average microcystins content (0.913 μgL^?1) being found in the sample collected from Bueng Nong Khot and the highest average cylindrospermopsins content (0.463 μgL^?1) being found in the sample collected from Bueng See Than. The application of 16S rRNA analyses to cyanobacterial isolates BKN2, BNK1, BNK2, and BST1 indicated that these isolates are most closely related to Limnothrix planctonica (JQ004026) (98 % similarity), Leptolyngbya sp. (FM177494) (99 % similarity), Microcystis aeruginosa (DQ887510) (99 % similarity), and Limnothrix redekei (FM177493) (99 % similarity), respectively.     

Application of water quality indices and analysis of the surface water quality monitoring network in semiarid North-Central Chile

Surface water quality has increasing importance worldwide and is particularly relevant in the semiarid North-Central Chile, where agriculture and mining activities are imposing heavy pressure on limited water resources. The current study presents the application of a water quality index in four watersheds of the 29°-33°S realm for the period 1999-2008, based on the Canadian Council of Ministers for the Environment approach and the Chilean regulation for irrigation water quality. In addition, two modifications to the index are tested and a comprehensive characterization of the existing monitoring network is performed through cluster analysis. The basins studied show fairly good water quality in the overall, specially the Limarí basin. On the other hand, the lower index values were obtained for the headwaters of Elqui, associated with the El Indio mining district. The first modification of the indicator (i.e., to consider parameters differentially according to their effect on human health or the environment) did not produce major differences with respect to the original index, given the generally good water quality. The second modification (i.e., to consider as threshold values the more restrictive figures derived from a set of regulations) yielded important differences in the indicator values. Finally, an adequate characterization of the monitoring network was obtained. The results presented spatial coherence and the information can be used as a basis for the optimization of the monitoring network if required.     

Monitoring and validating spatio-temporal dynamics of biogeochemical properties in Mersin Bay (Turkey) using Landsat ETM+

The objective of this study was to devise and validate simple models for estimating spatio-temporal dynamics of seven optically (in)active biogeochemical properties in Mersin Bay using Landsat 7 Enhanced Thematic Mapper Plus (ETM+) data and GIS. Spatio-temporal dynamics of Secchi depth (S (depth)), dissolved oxygen (DO), nitrite nitrogen (NO(2)-N), nitrate nitrogen (NO?-N), silicate (SiO?), 5-day biological oxygen demand (BOD5), and chlorophyll-a (Chl-a) were estimated using best-fit multiple linear regression (MLR) models as a function of Landsat 7 ETM+ and ground data in 2007 and 2008, latitude, longitude, and day of year. Validation of the MLR models against Landsat and ground data in 2005 led to r values ranging from 0.39 for NO?-N (P?=?0.008) to 0.79 for S (depth) (P?相似文献   

Persistent organochlorine residues in fish and water birds from the Biobio river,Chile

Concentrations of polychlorinated biphenyls (PCBs), DDT and its metabolites, HCH isomers and hexachlorobenzene (HCB) were determined in fish and birds from different locations in the Biobio river basin (central Chile). Samples collected near the mouth of the river contained high concentrations of PCBs, reflecting the massive use of these xenobiotics in the urban and industrial areas of Concepcion and Talcauano. Samples collected in the central part of the basin contained very high concentrations of lindane that coincide with the widespread use of lindane-based pesticides (purified -HCH) in this area. DDT was distributed homogeneously throughout the basin, except at Laguna Icalma, the source of the river in the Andes. Most PCB residues in fish and birds consisted of congeners between penta- and hepta-chlorobiphenyls. In fish, the predominant congeners were the pentachlorobiphenyl 23445 (IUPAC number 118) and the hexachlorobiphenyl 2234455 (PCB-153); in birds 224455 (PCB-180) prevailed.     

Occurrence and dominance of Cylindrospermopsis raciborskii and dissolved cylindrospermopsin in urban reservoirs used for drinking water supply,South China

The tropical cyanobacterium Cylindrospermopsis raciborskii is of particular concern for its invasive characteristics and production of the toxin cylindrospermopsin (CYN). The present study represents the first attempt to determine the distribution of C. raciborskii and CYN in tropical China. The presence of C. raciborskii and CYN, as well as the composition of phytoplankton, was determined from a total of 86 samples from 25 urban reservoirs for drinking water supply in Dongguan City of South China. The presence of C. raciborskii was observed in 21 of the 25 reservoirs and confirmed that this species has been widely distributed in the investigated reservoirs. C. raciborskii accounted for between 0.1 and 90.3 % of the total phytoplankton biomass and contributed to the majority of the phytoplankton in some reservoirs such as Tangkengbian and Xiagongyan. Its biomass was negatively correlated with NO₃ ^?-N concentration and Secchi depth. Dissolved CYN was detected in more than one-half of the reservoirs with concentrations up to 8.25 μg L^?1, and it positively correlated with C. raciborskii biomass. Dissolved microcystins (MCs) were detected in 12 of the 25 reservoirs with a maximum concentration 1.99 μg L^?1. Our data strongly suggest that C. raciborskii and CYN could be important health hazards in urban reservoirs of South China and that more data are needed for further assessment.     

Simultaneous quantitative monitoring of four indicator contaminants of emerging concern (CEC) in different water sources of Central India using SPE/LC-(ESI)MS-MS

Environmental occurrence of CECs poses a great threat to both aquatic life and human health. The aim of this study was to optimize and validate SPE/LC-(ESI)MS-MS method for simultaneous quantitative monitoring of two sub-classes of CECs (pharmaceuticals and hormones) and to estimate the concentrations of select CECs in environmental water samples. For all the tested analytes, recoveries in laboratory reagent water were greater than 81%. Average percent (relative standard deviation) RSD of the analytes in recovery, repeatability, and reproducibility experiments were ≤?10%. Determination coefficients (r²) of primidone, diclofenac, testosterone, and progesterone were estimated to be 0.9979, 0.9972, 0.9968, and 0.9962, respectively. Limits of detection (LOD) for primidone, diclofenac, testosterone, and progesterone were 4.63 ng/L, 5.36 ng/L, 0.55 ng/L, and 0.88 ng/L, respectively. Limits of quantification (LOQ) for primidone, diclofenac, testosterone, and progesterone were 14.72 ng/L, 17.06 ng/L, 1.766 ng/L, and 2.813 ng/L, respectively. Average recoveries in environmental water and wastewater samples were greater than 74% and RSD were ≤?7%. Trace levels (68.33–125.70 ng/L) of primidone were detected in four environmental water samples, whereas diclofenac was not detected in any of the tested sample. Trace levels of progesterone were observed in two environmental samples (16.64 –203.73 ng/L), whereas testosterone was detected in STP inlet sample (178.16 ng/L).     

Establishing minimum water level for Plastiras reservoir (Greece) combining water quality modelling with landscape aesthetics

A water quality model (MERES) is applied in the multi-purpose reservoir of Plastiras in Greece. The model was calibrated with limited field data using the standard trial and error procedure; next, it was applied for four scenarios of reservoir operation, which correspond to four values of minimum water levels (MWL). Model results were combined with landscape aesthetics to establish a “safe” MWL in the reservoir. MWL was proposed to be +784 m, a value that ensures a very good water quality by retaining the reservoir in the status of “a little beyond oligotrophic” and a very good quality of landscape with an acceptable area of dead zones; it also ensures an annual release of 127.5 hm³ of water within a reliability level of 90%. This quantity can be considered as acceptable from the water supply point of view.     

Retrieval of total suspended matter (TSM) and chlorophyll-a (Chl-a) concentration from remote-sensing data for drinking water resources

The concentrations of chlorophyll-a (Chl-a) and total suspended matter (TSM) are major water quality parameters that can be retrieved using remotely sensed data. Water sampling works were conducted on 15 July 2007 and 13 September 2008 concurrent with the Indian Remote-Sensing Satellite (IRS-P6) overpass of the Shitoukoumen Reservoir. Both empirical regression and back-propagation artificial neural network (ANN) models were established to estimate Chl-a and TSM concentration with both in situ and satellite-received radiances signals. It was found that empirical models performed well on the TSM concentration estimation with better accuracy (R ² = 0.94, 0.91) than their performance on Chl-a concentration (R ² = 0.62, 0.75) with IRS-P6 imagery data, and the models accuracy marginally improved with in situ spectra data. Our results indicated that the ANN model performed better for both Chl-a (R ² = 0.91, 0.82) and TSM (R ² = 0.98, 0.94) concentration estimation through in situ collected spectra; the same trend followed for IRS-P6 imagery data (R ² = 0.75 and 0.90 for Chl-a; R ² = 0.97 and 0.95 for TSM). The relative root mean square errors (RMSEs) from the empirical model for TSM (Chl-a) were less than 15% (respectively 27.2%) with both in situ and IRS-P6 imagery data, while the RMSEs were less than 7.5% (respectively 18.4%) from the ANN model. Future work still needs to be undertaken to derive the dynamic characteristic of Shitoukoumen Reservoir water quality with remotely sensed IRS-P6 or Landsat-TM data. The algorithms developed in this study will also need to be tested and refined with more imagery data acquisitions combined with in situ spectra data.     

Poly(sodium acrylamidoalkanoates) in water treatment

Poly(sodium 6-acrylamidocaproate), poly(sodium 11-acrylamidoundecanoate), poly(sodium 11-N-methylacrylamidoundecanoate) and poly(sodium 11-N-ethylacrylamidoundecanoate) have been synthesized. The performance of these anionic polyelectrolytes as coagulant aids in water treatment was assessed by the jar test. The effects of polymer dosage and pH on their performances were investigated in order to establish the optimum flocculation conditions. The effectiveness of these polyelectrolytes as well as a commercially available cationic polyamine organic coagulant aid was compared in terms of floc size, settling rate and the quality of treated water. Poly(sodium 6-acrylamidocaproate) and poly(sodium 11-acrylamidoundecanoate) were superior to poly(sodium 11-N-methylacrylamidoundecanoate) and poly(sodium 11-N-ethylacrylamidoundecanoate), and they are as effective as the commercial cationic coagulant aid.     

Environmental management plan (EMP) for Melamchi water supply project, Nepal

More than 1.5 million people live in the Kathmandu valley. The valley is facing an extreme shortage of water supply. At the same time the demand is escalating rapidly. To address this issue of scarcity of water, the government of Nepal has proposed a project of inter-basin transfer of water from Melamchi River located 40 km north-east of the Kathmandu valley. The project will cover two districts and three municipalities and will potentially have significant impacts on the environment. In accordance with the Environmental Protection Regulation of Nepal (1997), the Melamchi Water Supply Project (MWSP) has undergone an EIA during the feasibility study stage of the proposed project. The recommendations contained in the EIA were integrated into the project design for implementation in 2006. This paper summarizes the background of MWSP, the environmental concerns described in the EIA and the status of Environmental Management Plan (EMP) developed to address environmental compliance and other issues involving participation and support of the local people. This paper also provides some lessons to learn on the modalities of addressing the demands and grievances of the local people concerning environmental management.     

Spectrophotometric method for the determination of chromium (VI) in water samples

A simple and sensitive spectrophotometric method for the determination of chromium has been developed. The method is based on the diazotization of Dapsone in hydroxylamine hydrochloride medium and coupling with N-(1-Napthyl) Ethylene Diamine Dihydrochloride by electrophilic substitution to produce an intense pink azo-dye, which has absorption maximum at 540 nm. The Beer's law is obeyed from 0.02-1.0 microg mL(-1) and the molar absorptivity is 3.4854 L mol(-1) cm(-1). The Limits of quantification and Limit of detection of the proposed method are 0.0012 microg mL(-1) and 0.0039 microg mL(-1) respectively. The method has been successfully applied for the determination of chromium in water samples and the results were statistically evaluated with that of the reference method.