Major ion chemistry of shallow groundwater of a fast growing city of Central India

Nagpur City located in semiarid area of central India is a fast-growing industrial centre. In recent years, rapid development has created an increased demand for drinking water, which is increasingly being fulfilled by groundwater abstraction. The present study was undertaken to assess major ion chemistry of shallow groundwater to understand geochemical evolution of groundwater and water quality for promoting sustainable development and effective management of groundwater resources. A total of 47 water samples were collected from shallow aquifer of selected parts of the city and the water chemistry of various ions viz. Ca^2 +, Mg^2 +, Na⁺, K⁺, CO₃  ^2-_{3}^{\ \, 2-}, HCO₃  ^-_{3}^{\ \, -}, Cl⁻, SO₄  ^2-_{4}^{\ \,2-} and NO₃  ^-_{3}^{\ \,-} are carried out. The chemical relationships in Piper diagram identify Ca–HCO₃–Cl and mixed Ca–Na–HCO₃–Cl as most prevalent water types. Alkaline earth exceeds alkalis and weak acids exceed strong acids. Ionic ratios and Gibb’s diagram suggest that silicate rock weathering and anthropogenic activities are the main processes that determine the ionic composition in the study area. The nitrate appeared as a major problem of safe drinking water in this region. We recorded highest nitrate concentration, i.e., 411 mg/l in one of the dug well. A comparison of groundwater quality in relation to drinking water quality standards revealed that about half of the shallow aquifer samples are not suitable for drinking.     

Statistical source identification of metals in groundwater exposed to industrial contamination

Levels of selected metals Na, Ca, Mg, K, Fe, Mn, Cr, Co, Ni, Cd, Pb and Mn were estimated by flame atomic absorption spectrophotometry in groundwater samples from Kasur, a significant industrial city of Pakistan. Salient mean concentration levels were recorded for: Na (211 mg/l), Ca (187 mg/l), Mg (122 mg/l), K (87.7 mg/l), Fe (2.57 mg/l) and Cr (2.12 mg/l). Overall, the decreasing metal concentration order was: Na > Ca > Mg > K > Fe > Cr > Zn > Co > Pb > Mn > Ni > Cd. Significantly positive correlations were found between Na–Cr (r = 0.553), Na–Mn (r = 0.543), Mg–Fe (r = 0.519), Mg–Cr (r = 0.535), Pb–K (r = 0.506) and Pb–Ni (r = 0.611). Principal Component Analysis and Cluster Analysis identified tannery effluents as the main source of metal contamination of the groundwater. The present metal data showed that Cr, Pb and Fe levels were several times higher than those recommended for water quality by WHO, US-EPA, EU and Japan. The elevated levels of Cr, recorded as 21–42 fold higher compared with the recommended quality values, were believed to originate from the tanning industry of Kasur.     

Application of a Larval Medaka Assay to Evaluate the Fish Safety Level in Sagami River, Japan

Physico-chemical characteristics of some river and hand-dug well waters used for drinking and domestic purposes in the oil rich Niger Delta area of Nigeria were assessed using standard methods. The concentrations of the parameters in the river water samples ranged in the following order: pH (5.6–6.9), temperature (26.90–28.60°C), turbidity (23–63 NTU), electrical conductivity (52–184 μs/cm), DO (5.4–7.2 mg/l), BOD (21–57 mg/l), TDS (6.0–217 mg/l), PO₄ ³⁻ (0.19–1.72 mg/l), SO₄ ²⁻ (25–36.8 mg/l), NO₃ ⁻ (20.3–28 mg/l), Fe (6.07–15.71 mg/l), Zn (0.04–0.24 mg/l), Pb (0.01–0.17 mg/l), Ni (0.01–0.13 mg/l), Vn (0.01–0.20 mg/l) and Hg (0.001–0.002 mg/l). The concentrations of these parameters in the hand-dug well water ranged in the following order: pH (5.7–6.8) temperature (26–30°C), turbidity (134–171 NTU), electrical conductivity (160–340 μs/cm), DO (5.4–6.4 mg/l), BOD (13–34 mg/l), TDS (110–190 mg/l), PO₄ ³⁻ (0.84–1.84 mg/l), SO₄ ²⁻ (10.6–28.1 mg/l), NO₃ ⁻ (11.3–23 mg/l), Fe (13.17–16.31 mg/l), Ni (0.01–0.02 mg/l), Vn (0.01–0.04 mg/l) and Hg (0.001–0.004 mg/l). The concentrations of BOD, turbidity, NO₃ ⁻ and Fe in the water samples were above WHO and FMENV permissible limits for safe drinking water. The results suggest that the use of such waters for drinking and domestic purposes pose a serious threat to the health of the users and calls for the intervention of government agencies.     

Risk assessment due to intake of heavy metals through the ingestion of groundwater around two proposed uranium mining areas in Jharkhand,India

Heavy metal pollution of water resources can be apprehended in East Singhbhum region which is a highly mineralised zone with extensive mining of copper, uranium and other minerals. Ten groundwater samples were collected from each site and the heavy metal analysis was done by atomic absorption spectrophotometer. Analysis of the results of the study reveals that the concentration of iron, manganese, zinc, lead, copper and nickel in groundwater of Bagjata mining area ranged 0.06–5.3 mg l^− 1, 0.01–1.3 mg l^− 1, 0.02–8.2 mg l^− 1, 1.4–28.4 μg l^− 1, 0.78–20.0 μg l^− 1 and 1.05–20.1 μg l^− 1, respectively. In case of Banduhurang mining area, the range was 0.04–2.93 mg l^− 1, 0.02–1.1 mg l^− 1, 0.01–4.68 mg l^− 1, 1.04–33.21 μg l^− 1, 1.24–18.7 μg l^− 1 and 1.06–14.58 μg l^− 1, respectively. The heavy metals were found to be below the drinking water standards (IS:10500 1993) except iron (0.3 mg l^− 1) and manganese (0.1 mg l^− 1). The hazard quotients of the heavy metals for drinking water were below 1 posing no threat due to intake of water to the people for both the areas.     

Identification of mangrove water quality by multivariate statistical analysis methods in Pondicherry coast,India

Different multivariate statistical analysis such as, cluster analysis, principal component analysis, and multidimensional scale plot were employed to evaluate the trophic status of water quality for four monitoring stations. The present study was carried out to determine the physicochemical parameters of water and sediment characteristics of Pondicherry mangroves—southeast coast of India, during September 2008–December 2010. Seasonal variations of different parameters investigated were as follows: salinity (10.26–35.20 psu), dissolved oxygen (3.71–5.33 mg/L), pH (7.05–8.36), electrical conductivity (26.41–41.33 ms⁻¹), sulfide (1.98–40.43 mg/L), sediment texture sand (39.54–87.31%), silt (9.89–32.97%), clay (3.06–31.20%), and organic matter (0.94–4.64%). pH, temperature, salinity, sand, silt, clay, and organic matter indicated a correlation at P < 0.01. CA grouped the four seasons in to four groups (pre-monsoon, monsoon, post-monsoon, summer) and the sampling sites in to three groups. PCA identified the spatial and temporal characteristics of trophic stations and showed that the water quality was worse in stations 3 and 4 in the Pondicherry mangroves.     

Cyanobacterial Flora from Polluted Marine Shores

Citation of cyanobacterial cultures from the shores of south west coast of Gujarat, India and their relationship with sea water quality, influenced by extensive pollutant runoff is reported in this study. Intensity of pollution was evaluated by physico-chemical analysis of water. Higher load of suspended solids (60–1000 mg l⁻¹) and nutrients (PO₄ ⁻P: 1.3–4 μmole l⁻¹ and NO₃ ⁻N: 12.5–17.8 μmole l⁻¹) were persistent throughout the analysis. Community structure is seen to be influenced by such persistent pollution. Twenty nine cyanobacterial species were isolated belonging to 9 genera of 4 families, with an elevated occurrence of Oscillatoria and Lyngbya species. No heterocystous cyanobacteria were isolated throughout the study.     

Water quality and dissolved inorganic fluxes of N,P, SO<Subscript>4</Subscript>, and K of a small catchment river in the Southwestern Coast of India

The southwestern coast of India is drained by many small rivers with lengths less than 250 km and catchment areas less than 6,500 km². These rivers are perennial and are also the major drinking water sources in the region. But, the fast pace of urbanization, industrialization, fertilizer intensive agricultural activities and rise in pilgrim tourism in the past four to five decades have imposed marked changes in water quality and solute fluxes of many of these rivers. The problems have aggravated further due to leaching of ionic constituents from the organic-rich (peaty) impervious sub-surface layers that are exposed due to channel incision resulting from indiscriminate instream mining for construction-grade sand and gravel. In this context, an attempt has been made here to evaluate the water quality and the net nutrient flux of one of the important rivers in the southwestern coast of India, the Manimala river which has a length of about 90 km and catchment area of 847 km². The river exhibits seasonal variation in most of the water quality parameters (pH, electrical conductivity, dissolved oxygen, total dissolved solids, Ca, Mg, Na, K, Fe, HCO₃, NO₂-N, NO₃-N, P _\text-inorg_{\rm \text{-}inorg}, P _\text-tot_{\rm \text{-}tot}, chloride, SO₄, and SiO₂). Except for NO₃-N and SiO₂, all the other parameters are generally enriched in non-monsoon (December–May) samples than that of monsoon (June–November). The flux estimation reveals that the Manimala river transports an amount of 2,308 t y^− 1 of dissolved inorganic nitrogen, 87 t y^− 1 dissolved inorganic phosphorus, and 9246 t y^− 1 of SO₄, and 1984 t y^− 1 K into the receiving coastal waters. These together constitute about 23% of the total dissolved fluxes transported by the Manimala river. Based on the study, a set of mitigation measures are also suggested to improve the overall water quality of small catchment rivers of the densely populated tropics in general and the south western coast in particular.     

A spectrophotometric assay method for vanadium in biological and environmental samples using 2,4-dinitrophenylhydrazine with imipramine hydrochloride

A simple, rapid, and sensitive method involving the interaction of 2,4-dinitrophenylhydrazine with imipramine hydrochloride in presence of vanadium (V) in sulfuric acid medium has been proposed for the determination of vanadium. The purple-colored product developed showed an absorption maximum at 560 nm and was stable for 24 h. The working curve was linear over the concentration range of 0.1–2.8 μg ml^− 1, with sensitivity of detection of 0.0124 μg ml^− 1. Molar absorptivity and Sandell’s sensitivity were found to be 2.6 × 10⁴ l/mol cm and 0.0039 μg cm^− 1, respectively. The accuracy of the proposed method was assessed by Student’s t test and variance ratio F test, and the results were on par with the reported method. The method was successfully used in the determination of V in water, human urine, soil, and plant samples, and it was free from interference by various concomitant ions.     

Variations in sensitivity of two populations of Corophium Orientale (Crustacea: Amphipoda) towards cadmium and sodium laurylsulphate

The aim of this work was to monitor the sensitivity of two populations of Corophium orientale (Crustacea: Amphipoda) living at the outfall of two rivers (Magra and Serchio), comparing their responses towards two different toxicant solutions. Sensitivity was monthly checked performing the 96h-LC₅₀ static water only test with Cd(NO₃)₂ and SDS. If no significant differences were found between the two populations, they could have been employed without distinction to perform sediment toxicity bioassays. As regard to Cd, an increasing in LC₅₀ values from summer to winter was evident in each population (Serchio River: August 2003  =  1,36 mg/l, February 2004  =  7,23 mg/l; Magra River: August  =  1,21 mg/l, April  =  5,01 mg/l). This pattern was correlated to the droop of temperatures in winter period. The responses of the two populations towards the cadmium were compared using the ANOVA. The analysis showed any significant differences between the populations (p  =  0.12). The pattern of sensitivity towards SDS for the population living on Magra River was similar to the same pattern found for Cd; as regard to the population living on Serchio River, data were not enough to describe the annual pattern. Anyway, statistical analysis was performed and no significant differences were found between the two populations (p  =  0.34).     

Physicochemical and microbiological assessment of recreational and drinking waters

The present study was aimed to make an assessment of health risk due to pollution and human pathogenic bacteria associated with the recreational and drinking water sources in twin densely populated holy Indian cities Ayodhya and Faizabad. Though physicochemical studies revealed that the water available in the area is under recommended limits for human use, it is unsafe on account of poor microbiological quality of surface and ground water in the region. The most probable number (MPN) test results revealed the preponderance of ≥2,400 total coliforms (TC) (100 ml)^− 1 in river, pond, dug well and kund waters. Contrary to that, 94% tube wells, 32% hand pumps and 25% piped supply water were under safe limits having <3 TC (100 ml)^− 1. The shallow depth (~40 ft), water logging and presence of septic tanks in the near vicinity are the possible reasons of poor microbial quality of hand pump drinking water. The municipal supply water passes along sewage line where loose connections and/or cracks in pipe lead to mixing and contamination. The significant best quality of tube well water evident from the absence of TC could be attributed to the depth of well ≥150 ft and usually their location away from the habitation. A total of 263 bacteria from 186 water samples were isolated, and at least five genera of enteric bacteria from various water sources were identified morphologically and biochemically as Escherichia coli, Klebsiella sp., Enterobacter sp., Shigella sp. and Salmonella sp. The serotyping of 72 E. coli and 36 Salmonella sp. revealed 51 as E. coli O157 and 20 as Salmonella sp. The presence of enteric pathogens in water sources pose threat to human health and therefore call for immediate remedial measures.     

Determination of road dust loadings and chemical characteristics using resuspension

The contribution of fugitive dust from traffic to air pollution can no longer be ignored in China. In order to obtain the road dust loadings and to understand the chemical characteristics of PM₁₀ and PM_2.5 from typical road dust, different paved roads in eight districts of Beijing were selected for dust collection during the four seasons of 2005. Ninety-eight samples from 28 roads were obtained. The samples were resuspended using equipment assembled to simulate the rising process of road dust caused by the wind or wheels in order to obtain the PM₁₀ and PM_2.5 filter samples. The average road dust loading was 3.82 g m^− 2, with the highest of 24.22 g m^− 2 being in Hutongs in the rural–urban continuum during winter. The road dust loadings on higher-grade roads were lower than those on lower-grade roads. Attention should be paid to the pollution in the rural–urban continuum areas. The sums of element abundances measured were 16.17% and 18.50% for PM₁₀ and PM_2.5 in road dust. The average abundances of OC and EC in PM₁₀ and PM_2.5 in road dust were 11.52%, 2.01% and 12.50%, 2.06%, respectively. The abundance of elements, water-soluble ions, and OC, EC in PM₁₀ and PM_2.5 resuspended from road dust did not change greatly with seasons and road types. The soil dust, construction dust, dust emitted from burning coal, vehicle exhaust, and deposition of particles in the air were the main sources of road dust in Beijing. Affected by the application of snow-melting agents in Beijing during winter, the amount of Cl⁻ and Na⁺ was much higher during that time than in the other seasons. This will have a certain influence on roads, bridges, vegetations, and groundwater.     

Does biodiversity of macroinvertebrates and genome response of Chironomidae larvae (Diptera) reflect heavy metal pollution in a small pond?

The investigation was carried out on a small pond situated on a recent mine spoil at Bolesław in the Olkusz region with Zn–Pb ore deposits. Water of the pond had pH 7.2–8.5 and low concentrations of heavy metals. Concentrations of Pb (487 μg g^− 1) and Zn (1,991 μg g^− 1) in the sediment were very high and potentially could lead to toxicological effects. In the pond, 48 taxa of macroinvertebrates belonging to Oligochaeta and water stages of Ephemeroptera, Odonata, Megaloptera, Trichoptera, Heteroptera, Coleoptera and Diptera (mainly Chironomidae family) were found. The influence of heavy metals on macroinvertebrates diversity was not found. Effect of heavy metal pollution was observed on the appearance of chromosome aberrations in the polytene chromosomes of Chironomidae larvae. It was manifested by two ways: (1) in Kiefferulus tendipediformis and Chironomus sp. chromosome rearrangements in fixed state (tandem fusion and homozygous inversions), indicated intensive process of speciation; (2) in Chironomus sp., K. tendipediformis, Glyptotendipes gripekoveni (Chironomidae) somatic chromosome rearrangements (inversions, deficiencies, specific puffs, polyploidy) affected few cells of every individual. The somatic functional and structural alterations in Chironomidae species are particular suitable as biomarkers—they can be easily identified and used for detecting toxic agents in the environment.     

Survey of Levels of Phthalate Ester Plasticizers in a Sewage Lagoon Effluent and a Receiving Stream

In this study, samples from a sewage treatment lagoon and those from a receiving stream were analyzed for their phthalate esters content. Knowledge of the distribution of ubiquitous phthalate esters in the sewage lagoon and the receiving stream was necessary because of the reports of their subtle toxicity to aquatic biota and humans. Liquid–liquid extraction, Clean-up experiment and High Performance Liquid Chromatography (HPLC) were the methods employed for the quantitative determination of the Phthalates. A study of uncontaminated water was done to establish blank levels. The sewage lagoon and the receiving stream were grossly polluted as several phthalate ester plasticizers: DMP, DEP, DPhP, DBP, DEHP, DOP and DINP were found present at monthly mean levels of between 24.02 mg/L and 139.25 mg/L in the sewage treatment lagoon and 10.41 mg/L and 80.53 mg/L in the receiving stream. The results showed higher levels of phthalate esters in the sewage lagoon compared to the receiving stream. The sewage lagoon was identified as a pollution point source into the receiving stream. Levels of phthalates obtained from the receiving stream are much higher than the water criteria of 3 μg/L phthalates recommended by the United States Environmental Protection Agency (USEPA) for the protection of fish and other aquatic life in water and the Suggested No-Adverse Effect Levels (SNAEL) of 7.5–38.5 μg/L for drinking water. This should give cause for great environmental concern. Peoples’ health downstream is at stake and so is the ‘health’ of the ecosystem.     

Determination of total petroleum hydrocarbons (TPH) in agricultural soils near a petrochemical complex in Guangzhou,China

The total petroleum hydrocarbons (TPH) pollution in regional agricultural soils was investigated. Seventy soil samples collected from surface layers (0–20 cm) and horizons of five selected pedons in the vicinity of a petrochemical complex in Guangzhou, China were analyzed, and the vertical variation and spatial variability of TPH were evaluated. The TPH concentration in top soils around the petrochemical complex ranged from 1,179.3 to 6,354.9 mg kg^− 1, with the average of 2,676.6 mg kg^− 1. Furthermore, significant differences between land-use types showed that the TPH concentration in top soils was strongly influenced by accidental spills. Both the TPH trends in pedons and the identified hot-spot areas also showed that the accidental explosions or burning accidents were mainly responsible for the pollution. The results reported here suggest that the regular monitoring and inspection shall be conducted for safety and to avoid or minimize the accidents, and the effective measures should be taken to remediate the contaminated areas and to assure that the important industrialization of Guangzhou area would not mean human health risks near the petrochemical complex.     

Implications of climate change for evaporation from bare soils in a Mediterranean environment

The purpose of this study was to predict quantitative changes in evaporation from bare soils in the Mediterranean climate region of Turkey in response to the projections of a regional climate model developed in Japan (hereafter RCM). Daily RCM data for the estimation of reference evapotranspiration (ET _r) and soil evaporation were obtained for the periods of 1994–2003 and 2070–2079. Potential evaporation (E _p) from bare soils was calculated using the Penman–Monteith equation with a surface resistance of zero. Simulation of actual soil evaporation (E _a) was carried out using Aydin model (Aydin et al., Ecological Modelling 182:91–105, 2005) combined with Aydin and Uygur (2006, A model for estimating soil water potential of bare fields. In Proceedings of the 18th International Soil Meeting (ISM) on Soils Sustaining Life on Earth, Managing Soil and Technology, Sanliurfa, 477–480pp.) model of predicting soil water potential at the top surface layer of a bare soil, after performances of Aydin model (R ² = 94.0%) and Aydin and Uygur model (R ² = 97.6) were tested. The latter model is based on the relations among potential soil evaporation, hydraulic diffusivity, and soil wetness, with some simplified assumptions. Input parameters of the model are simple and easily obtainable such as climatic parameters used to compute the potential soil evaporation, average diffusivity for the drying soil, and volumetric water content at field capacity. The combination of Aydin and Aydin and Uygur models appeared to be useful in estimating water potential of soils and E _a from bare soils, with only a few parameters. Unlike ET _r and E _p projected to increase by 92 and 69 mm (equivalent to 8.0 and 7.3% increases) due to the elevated evaporative demand of the atmosphere, respectively, E _a from bare soils is projected to reduce by 50 mm (equivalent to a 16.5% decrease) in response to a decrease in rainfall by 46% in the Mediterranean region of Turkey by the 2070s predicted by RCM, and consequently, to decreased soil wetness in the future.     

Rinodina sophodes (Ach.) Massal.: a bioaccumulator of polycyclic aromatic hydrocarbons (PAHs) in Kanpur City, India

The aim of this study is to determine the possibility of using Rinodina sophodes (Ach.) Massal., a crustose lichen as polycyclic aromatic hydrocarbons (PAHs) bioaccumulator for evaluation of atmospheric pollution in tropical areas of India, where few species of lichens are able to grow. PAHs were identified, quantified and compared to evaluate the potential utility of R. sophodes. The limit of detection for different PAHs was found to be 0.008–0.050 μg g^− 1. The total PAHs in different sites were ranged between 0.189 ± 0.029 and 0.494 ± 0.105 μg g^− 1. The major sources of PAHs were combustion of organic materials, traffic and vehicular exhaust (diesel and gasoline engine). Significantly higher concentration of acenaphthylene and phenanthrene indicates road traffic as major source of PAH pollution in the city. Two-way ANOVA also confirms that all PAHs content showed significant differences between all sampling sites (P 1%). This study establishes the utility of R. sophodes in monitoring the PAHs accumulation potentiality for development of effective tool and explores the most potential traits resistant to the hazardous environmental conditions in the tropical regions of north India, where no such other effective way of biomonitoring is known so far.     

Aerosol characteristics and surface radiative forcing components during a dust outbreak in Gwangju, Republic of Korea

Atmospheric surface aerosol radiative forcing (SARF) ΔF, forcing efficiency ΔF_e and fractional forcing efficiency ΔFF_e evaluated from cloud-screened narrowband spectral and thermal-offset-corrected radiometric observations during the Asia dust outbreak episodes in Gwangju, Republic of Korea are reported in this study. Columnar aerosol optical properties (aerosol optical depth (AOD), τ _aλ, Angstrom exponent α, mass concentration of fine and coarse mode particles) were also reported for the station between January 2000 and May 2001 consisting of 211cloud-free days. Results indicate that majority of the AOD were within the range 0.25–0.45 while some high aerosol events in which AODs ≥ 0.6 were observed during the severe dust episodes. For example, AOD increases from annual average value of 0.34 ± 0.13 at 501 nm to values >0.60 during the major dust events of March 27–30 and April 7–9, 2000, respectively. The α _{501–870 nm} which is often used as a qualitative indicator of aerosol particle size had values ranging from 0.01 to 1.77. The diurnal forcing efficiency ΔDF_e at Gwangju was estimated to be −81.10 ± 5.14 W m ⁻²/τ _{501 nm} and −47.09 ± 2.20 W m ⁻²/τ _{501 nm} for the total solar broadband and visible band pass, respectively while the fractional diurnal forcing efficiency ΔFDF_e were −15.8 ± 0.64%/τ _{501 nm} and −22.87 ± 1.13%/τ _{501 nm} for the same band passes. Analyses of the 5-day air-mass back trajectories were further developed for Gwangju in order to classify the air-mass and types of aerosol reaching the site during the Asia dust episodes.     

Deterioration of water quality of Surma river

Surma River is polluted day by day by human activities, poor structured sewerage and drainage system, discharging industrial and household wastes. The charas (natural channels) are responsible for surface runoff conveyance from its urban catchments to the receiving Surma River. Water samples have been collected from a part of Surma River along different points and analyzed for various water quality parameters during dry and monsoon periods. Effects of industrial wastes, municipal sewage, and agricultural runoff on river water quality have been investigated. The study was conducted within the Chattak to Sunamganj portion of Surma River, which is significant due to the presence of two major industries – a paper mill and a cement factory. The other significant feature is the conveyors that travel from India to Chattak. The river was found to be highly turbid in the monsoon season. But BOD and fecal coliform concentration was found higher in the dry season. The water was found slightly acidic. The mean values of parameters were Conductivity 84–805 μs; DO: dry-5.52 mg/l, monsoon-5.72 mg/l; BOD: dry-1mg/l, monsoon-0.878 mg/l; Total Solid: dry-149.4 mg/l, monsoon-145.7 mg/l. In this study, an effort has been taken to investigate the status of concentration of phosphate (PO⁻⁴) and ammonia–nitrogen (NH₄–N) at four entrance points of Malnichara to the city, Guali chara, Gaviar khal and Bolramer khal. Data has been collected from March–April and September–October of 2004. Concentrations have been measured using UV Spectrophotometer. Although the phosphate concentration has been found within the limit set by DOE for fishing, irrigation and recreational purposes, however ammonia–nitrogen has been found to exceed the limit.     

Residual fate and persistence of endosulfan (50 WDG) in Bengal gram (Cicer arietinum)

A detailed study has been presented on heavy metal content of the Iture Estuary. Waters of the Sorowie and Kakum rivers that supply water into the Estuary were investigated to ascertain heavy metal pollution levels due to anthropogenic activities. Concentration s of Cd, Zn, Se and Pb were measured. The study shows pre-occupying pollution levels that constitute a threat to both terrestrial and aquatic ecosystems. The abundance of metals in the Estuary is in the order Zn > Pb > Cd > Se. The level of Cd in the Iture Estuary ranged between 0.011 mg/l and 0.041 mg/l while Se was in the range 0.018 mg/l to 0.029 mg/l, Pb 0.020 mg/l to 0.075 mg/l and Zn 0.040 to 2.45 mg/l. The impact of contaminated water from the Sorowie River on the Iture Estuary was outstanding and the study points out the importance of the Sorowie River as a primary pollution source to the Iture Estuary. The pollution of the Iture Estuary was found to be connected to human activities in its catchments.     

Water quality assessment using integrated modeling and monitoring in Narva Bay, Gulf of Finland

A coupled three-dimensional hydrodynamic–ecological model was used for the assessment of water quality in Narva Bay during one biologically active season. Narva Bay is located in the south-eastern Gulf of Finland. Narva River with a catchment’s area covering part of Russia and Estonia discharges water and nutrients to Narva Bay. The ecological model includes phytoplankton carbon, nitrogen and phosphorus, chlorophyll a, zooplankton, detritus carbon, nitrogen and phosphorus, inorganic nitrogen, inorganic phosphorus and dissolved oxygen as state variables. Both the hydrodynamic and ecosystem models were validated using a limited number of measurements. The hydrodynamic model validation included comparison of time series of currents and temperature and salinity profiles. The ecological model results were compared with the monitoring data of phytoplankton biomass, total nitrogen and phosphorus and dissolved oxygen. The comparison of hydrodynamic parameters, phytoplankton biomass, surface layer total phosphorus and dissolved oxygen and near-bottom layer total nitrogen was reasonable. Time series of spatially mean values and standard deviations of selected parameters were calculated for the whole Narva Bay. Combining model results and monitoring data, the characteristic concentrations of phytoplankton biomass, total nitrogen and phosphorus and near-bottom dissolved oxygen were estimated. Phytoplankton biomass and total phosphorus showed seasonal variations, of 0.6–1.1 and 0.022–0.032 mg/l, respectively, during spring bloom, 0.1–0.3 and 0.015–0.025 mg/l in summer and 0.2–0.6 and 0.017–0.035 mg/l during autumn bloom. Total nitrogen and near-bottom oxygen concentrations were rather steady, being 0.25–0.35 and 2–6 mg/l, respectively. The total nitrogen and phosphorus concentrations show that according to the classification of Estonian coastal waters, Narva Bay water belongs to a good water quality class.