Surface water quality contamination source apportionment and physicochemical characterization at the upper section of the Jakara Basin, Nigeria

The present study investigates the surface water quality of three important tributaries of Jakara Basin, northwestern Nigeria to provide an overview of the relationship and sources of physicochemical and biological parameters. A total of 405 water samples were collected from 27 sampling points and analyzed for 13 parameters: dissolved oxygen (DO), 5-day biochemical oxygen demand (BOD₅), chemical oxygen demand (COD), suspended solids (SS), pH, ammonia-nitrogen (NH₃NL), dissolved solids (DS), total solids (TS), nitrates (NO₃), chloride (Cl), phosphates (PO₄), Escherichia coli (E. coli) and fecal coliform bacteria (FCB). Pearson’s product–moment correlation matrix and principal component analysis (PCA) were used to distinguish the main pollution sources in the basin. Four varimax components were extracted from PCA, which explained 84.86, 83.60, and 78.69 % of the variation in the surface water quality for Jakara, Tsakama, and Gama-Kwari Rivers, respectively. Strong positive loading included BOD₅, COD, NH₃NL, E. coli, and FCB with negative loading on DO attribute to a domestic waste water pollution source. One-way ANOVA revealed that there was no significant difference in the mean of the three water bodies (p?>?0.05). It is therefore recommended that the government should be more effective in controlling the point source of pollution in the area.     

Phytoplankton Patterns in Massachusetts Bay—1992–2007

The Massachusetts Water Resources Authority (MWRA) conducts a comprehensive multidisciplinary monitoring program in Massachusetts Bay, Cape Cod Bay, and Boston Harbor to assess the environmental effects of a relocated secondary-treated effluent outfall. Through 2007, 8.7 years of baseline data and 7.3 years of postdiversion data (16 total years), including species level estimates of phytoplankton and zooplankton abundance, have been collected. MWRA’s monitoring program and other studies make this region one of the most thoroughly studied and well-described marine systems in the world. The data show that the diversion of MWRA effluent from the harbor to the bay has decreased nutrients concentrations and improved water quality in the harbor (e.g., higher dissolved oxygen, lower chlorophyll). The diversion also resulted in an increase in dissolved inorganic nutrients (especially ammonium) in the vicinity of the bay outfall, but no obvious impacts such as increased biomass or decreased bottom water dissolved oxygen have been observed. Regional changes in phytoplankton and zooplankton unrelated to the diversion have been seen, and it is clear that the bays are closely connected both physically and ecologically with the greater Gulf of Maine. Direct responses to modifications of the nutrient field within a 10 × 10-km area centered near the midpoint of the 2-km long outfall diffuser in Massachusetts Bay (a.k.a. the nearfield) have not been seen in the plankton community. However, plankton variability in the bays has been linked to large regional to hemispheric scale (NAO) processes.     

Evaluating the effectiveness of bank infiltration process in new Aswan City, Egypt

Riverbank filtration (RBF) is an efficient and low-cost natural alternative technology for water supply application in which surface water contaminants are removed or degraded as the infiltrating water moves from the river to the pumping wells. In this study, a full-scale RBF site consisting of three vertical wells installed 50 m from Nile bank was investigated. The RBF systems are particularly well suited for providing better water quality than withdrawal directly from the Nile River to produce drinking water for New Aswan city. The study is carried out by taking samples over 1 year from riverbank filtrates wells, Nile River (as induced surface water), and some production wells were collected and analyzed. Physicochemical and microbiological measurements such as turbidity, dissolved oxygen, total suspended solids, total organic carbon, total dissolved solids, electrical conductivity, pH, Fe, Mn, NH₃, NO₂, NO₃, PO₄, Ca, Mg, Na, K, HCO₃, SO₄, Cl, total bacteria, and total coliform were carried out. The results of bank filtrate were compared with those of the natural groundwater and previous reported Nile water. Chemical and bacterial quality parameters of RBF are under the allowable limits for drinking water. Moreover, bank filtration is simultaneously improved the ambient groundwater and cleaned Nile water in the studied area. Result of this full-scale RBF plant showed the effectiveness of riverbank filtration as a proven treatment technique in Nile Valley with a fraction of cost comparing to conventional surface treatment plants.     

Chemistry and discharge characteristics of Odukpani junction springs, Calabar Flank, south-eastern Nigeria

A 6-month study spanning the rainy and dry seasons was conducted on Odukpani Junction springs (Nigeria) to assess the variation in discharge and physico-chemical parameters. The study also evaluated the impact of geology and indiscriminate disposal of wastes on spring water quality. The results indicate a poor correlation between discharge (Q) and amount of rainfall (R). This is attributed to the distance of the meteorological station and the sampled localities, thus eliminating micro rainfall data. However, Q increased with an increase in R. The variation of ions with time was not large; however, concentrations were higher during the rainy season in most cases. Three major chemical facies (Ca-HCO₃, Ca-SO₄, K-HCO₃) identified show major relationship with lithology. Multiple regression equations have been developed to predict the total dissolved solids (TDS), electrical conductivity (EC) and discharge (Q). The level of nitrate is high (9-43 mg/l) compared with the World Health Organisation (WHO) limits of 10.0 mg/l. This is attributed to the indiscriminate dumping of domestic, human and animal wastes. Other parameters determined are within the limits acceptable for potable water by the Nigerian Federal Environmental Protection Agency (NFEPA) and WHO.     

Nutrient uptake in a highly turbid estuary (the Humber, United Kingdom) and adjacent coastal waters

Surveys were conducted in April and June 1995 to quantify the uptake of dissolved nutrients in a highly turbid estuary (the Humber, United Kingdom) and to determine the factors controlling nutrient uptake rates. A combination of isotope labelling methods were used in conjunction with on-deck incubation techniques to estimate the uptake of dissolved nutrients (PO₄ ^3?, NH₄ ⁺, NO₃ ^?, and urea) in surface samples collected from coastal waters. Similarly, isotope labelling and laboratory incubgation techniques were employed to estimate dissolved nitrogen uptake (NH₄ ⁺, NO₃ ^?, and urea) in surface samples collected from the estuary mouth. Nutrient uptake rates were at the low end of ranges for coastal and estuarine environments reported in the literature. Concentrations of chlorophyll and the availability of photosynthetically active radiation were identified as potentially important factors controlling the uptake rates of nutrients. Uptake rates of dissolved nitrogen in the Humber mouth appeared to be related to the location of smapling sites. Depletion rates of dissolved nutrients in situ were estimated on the basis of integrated water column nutrient uptake rates and indicated assimilation of up to 16% of nutrients in the entire water column. Estimated depletion rates did not indicate preferential loss of any of the nutrient species investigated.     

Nitrogen pools in Georgia coastal waters

The amount of nitrogen present as ammonia, nitrate, nitrite, dissolved organic nitrogen, and particulate nitrogen was determined for nearshore Georgia shelf waters and for tidal water inundating a 0.5 hectare dikedSpartina alterniflora salt marsh in the adjacent estuary. Concentrations of ammonia, nitrate, and nitrite were comparatively low in offshore water (<2.2 μg-at N/1), and in high tide water in the marsh (<9.9 μg-at N/1). High concentrations of ammonia, up to 73.4 μg-at N/1, were measured in low tide water draining from marsh. The largest pools of nitrogen in offshore water and in high tide water in the marsh creek were dissolved organic nitrogen (DON) (2.5 to 20.4 μg-at N/1) and particulate nitrogen (PN) (0.1 to 30.0 μg-at N/1). Concentrations in marsh creek water at low tide were higher, ranging from 4.4 to 38.0 μg-at N/1 for DON and from 13.0 to 239.0 μg-at N/1 for PN. Comparisons of the average concentrations of dissolved and particulate forms of nitrogen in the marsh tidal creek during flood and during ebb tide suggested no net movement of the inorganic nitrogen nutrients, a net influx of PN to the marsh, and a net outflux of DON from the marsh.     

Influence of water chemistry on the distribution of an acidophilic protozoan in an acid mine drainage system at the abandoned Green Valley coal mine,Indiana, USA

Euglena mutabilis, a benthic photosynthetic protozoan that intracellularly sequesters Fe, is variably abundant in the main effluent channel that contains acid mine drainage (AMD) discharging from the Green Valley coal mine site in western Indiana. Samples of effluent (pH 3.0–4.6) taken from the main channel and samples of contaminated stream water (pH 3.3 to 8.0) collected from an adjacent stream were analyzed to evaluate the influence of water chemistry on E. mutabilis distribution. E. mutabilis communities were restricted to areas containing unmixed effluent with the thickest (up to 3 mm) benthic communities residing in effluent containing high concentrations of total Fe (up to 12110 mg/l), SO₄ (up to 2940 mg/l), Al (up to 1846 mg/l), and Cl (up to 629 mg/l). Communities were also present, but much less abundant, in areas with effluent containing lower concentrations of these same constituents. In effluent where SO₄ was most highly concentrated, E. mutabilis was largely absent, suggesting that extremely high concentrations of SO₄ may have an adverse effect on this potentially beneficial Fe-mediating, acidophilic protozoan.     

Assessment of the quality of groundwater from different parts of southeastern Nigeria for potable use

Groundwater samples from three different states of southeastern Nigeria were analyzed for a range of physicochemical parameters and heavy metal constituents in order to determine their potability as drinking water sources. The results indicate that the physicochemical parameters (pH, temperature, TDS, TH, electrical conductivity, Cl^?, NO₃ ^? and SO₄ ^2?) tested for have most of their values fall within the permissible limits given by the Nigerian and World Health Organization standards for drinking water quality. The results also reveal that apart from Cu and Pb the rest of the tested heavy metals (As, Zn, Ni, total Fe, Cd and Mn) recorded values that are significantly above the maximum permissible limits for drinking water purposes and therefore have the potential to cause health impacts for long-term potable use. On the basis of principal component analysis, the sources of the measured chemical constituents are likely to be predominantly geogenic (weathering of soluble minerals in the formations) and partly anthropogenic (industrial effluent, agricultural practices and mining activities). Single-factor ANOVA tests indicated insignificant differences in the datasets within/between states or geological units. Caution or adequate treatment is generally required when utilizing the groundwater from the area for drinking purpose due to the elevated metal concentrations and rating as poor to unsuitable water quality.     

Macrobenthic communities from wetland impoundments and adjacent open marsh habitats in South Carolina

Forty-eight core and grab samples were taken from two impoundments and an adjacent tidal creek and salt marsh during each of six sampling periods (January, June and November 1983; and January, April and July 1984). Habitats sampled within the impoundments included the perimeter ditch and shallow vegeted areas dominated byRuppia maritima, Spartina alterniflora, andScirpus robustus. The adjacent tidal creek bottom and low marsh ofS. alterniflora were sampled for comparison with the impoundment sites. Major differences in faunal composition and density of macrobenthic invertebrates were observed between habitats in this study. Macrobenthic density was highest (475 individuals 0.05 m^?2) at the impoundment site dominated byScripus robustus, where oligochaetes were abundant. The open marsh site had a density of 254 individuals 0.05 m^?2. Among unvegetated sites, density for all sampling periods was higher in Chainey Creek than in the perimeter ditches of the impoundments. The total number of taxa was highest for the open marsh and tidal creek sites. The impoundments contained vegetated sites which were inhabited by fewer species than nonimpounded sites, while the perimeter ditch sites were comparatively depauperate. Cluster and nodal analyses identified four broad assemblages based on habitat: 1) an open marsh assemblage, 2) a creek assemblage, 3) a eurytopic assemblage, and 4) an impoundment assemblage. The separation of faunal assemblages by sampling site rather than sampling period suggests that physical differences between habitats were important factors determining distribution patterns.     

Characteristics of dissolved organic nitrogen (DON) in the surface water of Beijing Olympic Forest Park

The characteristics of dissolved organic nitrogen (DON) in surface water from Beijing Olympic Forest Park (BOFP) were investigated in this study. Nanofiltration (NF) pretreatment procedure using two NF membranes (NF90 and NF270) was applied to increase the accuracy and precision of DON measurements in surface water samples with high dissolved inorganic nitrogen/total dissolved nitrogen (DIN/TDN) ratios. Compared to NF90, NF270 showed better performance in lowering the DIN/TDN ratio and retaining DOC in both the synthetic water and raw water samples. DON concentrations ranged from 0.01 to 0.83 mg N L^?1 in water samples collected over four different months and showed a seasonal variation. The DON increased in summer due to the higher activity of decomposers on recent litterfall or because of a higher production of biomass in the surface water body. The molecular weight (MW) fractions of <3 kDa accounted for more than 50 % of the total DOC concentration and the fractions of <3 kDa contributed to more than 48 % of the total DON concentration. It could be concluded that most of the DON present in surface water of BOFP was composed of small molecules, which were mainly composed of monomers such as amino acids and urea, readily available for the uptake by phytoplankton and heterotrophic bacteria.     

Hydrogeochemistry of mine, surface and groundwaters from the Sanggok mine creek in the upper Chungju Lake, Republic of Korea

 The Sanggok mine used to be one of the largest lead-zinc mines in the Hwanggangri mining district, Republic of Korea. The present study characterizes the heavy metal contamination in the abandoned Sanggok mine creek on the basis of physico-chemical properties of various kinds of water samples (mine, surface and groundwater). Hydrochemistry of the water samples is characterized by the relatively significant enrichment of Ca²⁺, HCO₃ ^–, NO₃ ^– and Cl^– in the surface and groundwaters, whereas the mine water is relatively enriched in Ca²⁺, Mg²⁺, heavy metals, and HCO₃ ^– and SO₄ ^2–. The more polluted mine water has a lower pH and higher Eh, conductivity and TDS values. The concentrations of some toxic elements (Al, As, Cd, Cu, Fe, Mn, Pb, Se, Sr, Pb and Zn) are tens to hundreds of times higher in the mine water than in the unpolluted surface and groundwaters. However, most immobile toxic pollutants from the mine drainage were quickly removed from the surface water by the precipitation of Al and Fe oxyhydroxides. Geochemical modeling showed that potentially toxic heavy metals might exist largely in the forms of MSO₄ ^2– and M²⁺ in the mine water. These metals in the surface and groundwaters could form M²⁺, CO₃ ^2– and OH^– complex ions. Computer simulation indicates that the saturation indices of albite, alunite, anhydrite, chlorite, fluorite, gypsum, halloysite and strontianite in the water samples are undersaturated and have progressively evolved toward the saturation condition. However, barite, calcite, chalcedony, dolomite, gibbsite, illite and quartz were in equilibrium, and only clay minerals were supersaturated. Ground and mine waters seemed to be in equilibrium with kaolinite field, but some surface water were in equilibrium with gibbsite and seceded from the stability field of quartz. This indicates that surface water samples in reaction with carbonate rocks would first equilibrate with carbonate minerals, then gibbsite to kaolinite. Investigations on water quality and environmental improvement of the severely polluted Sanggok creek, as well as remediation methods on the possible future pollution of the groundwater by the acid mine drainage from the abandoned metal mines, are urgently required. Received: 4 February 2000 · Accepted: 9 May 2000     

Elemental hydrochemistry assessment on its variation and quality status in Langat River, Western Peninsular Malaysia

This paper discusses the hydrochemistry variation and its quality status in Langat River, based on the chemistry of major ions, metal concentrations and suitability for drinking purposes. Water samples were collected from 30 different stations to assess their hydrochemical characteristics. The physico-chemical parameters selected were temperature, electrical conductivity, total dissolved solids (TDS), salinity, dissolved oxygen , pH, redox potential, HCO₃, Cl, SO₄, NO₃, Ca, Na, K, Mg, ²⁷Al, ¹³⁸Ba, ⁹Be, ¹¹¹Cd, ⁵⁹Co, ⁶³Cu, ⁵²Cr, ⁵⁷Fe, ⁵⁵Mn, ⁶⁰Ni, ²⁰⁸Pb, ⁸⁰Se and ⁶⁶Zn to investigate the variation of the constituents in the river water. Most of the parameters comply with the Drinking Water Quality Standard of the World Health Organization and the Malaysian National Standard for Drinking Water Quality by the Malaysia Ministry of Health except for EC, TDS, Cl, HCO₃, SO₄, Na, Mg, Al, Fe and Se. The results show that the Langat River is unsuitable for drinking purposes directly without treatment.     

Hydrochemical assessment of pond and stream water near abandoned barite mine sites in parts of Oban massif and Mamfe Embayment,Southeastern Nigeria

Hydrochemical studies were carried out in parts of Oban Massif and Mamfe Embayment, Southeastern Nigeria to examine the contributions of barite mining activities on water quality. Pond and stream water samples were collected from six abandoned barite mines and adjoining streams areas during dry and wet seasons. These samples were analysed for physicochemical parameters using standard techniques. The results showed that the quality of water samples in the vicinity of barite mine sites was characterized by low pH, low mineralization, high suspended solids and deep colour. Sodium (Na⁺) and calcium (Ca²⁺) are the dominant cations and bicarbonate (HCO₃ ^?) and sulphate (SO₄ ^2?) the dominant anions. The low concentration of dissolved silica, relatively high concentrations of Na⁺, HCO₃ ^? and SO₄ ^2? suggest a combined influence of silicate, carbonate and weathering of mine spoils. The total dissolved solids, total suspended solids, electrical conductivity and major ions (except Na⁺ and K⁺) are higher for water draining barite mines from Cretaceous sediments, while Na⁺, K⁺, Ba²⁺ are higher in basement rock areas. Correlation and factor analyses suggest that the main components of the water samples are related to anthropogenic, geogenic, mineralization and environmental controls, while Gibbs diagram plots indicate weathering as the main process controlling the chemistry of water. Computed values of hardness and some irrigational parameters showed that the pond and stream water samples are generally soft and can be used for irrigation. Generally, the water quality satisfied the WHO (2008) and NIS (2007) standards for domestic, agriculture and industrial. However, there is the need to assess the impact of the pollution on the ecosystem and human health while remediation measures are being considered.     

Hydrogeochemical assessment of surface and groundwater resources of Korba coalfield,Central India: environmental implications

The present study assesses the impact of coal mining on surface and groundwater resources of Korba Coalfield, Central India. Accordingly, water samples collected from various sources are analyzed for major ions, trace elements, and other mine effluent parameters. Results show that the groundwater samples are slightly acidic, whereas river water and mine water samples are mildly alkaline. Elevated concentrations of Ca²⁺, Na⁺, HCO₃ ^?, and SO₄ ^2? alongside the molar ratios (Ca²⁺+Mg²⁺)/(SO₄ ^2?+HCO₃ ^?) <1 and Na⁺/Cl^? >1 suggest that silicate weathering (water-rock interaction) coupled with ion exchange are dominant solute acquisition processes controlling the chemistry of groundwater in the study area. The overall hydrogeochemistry of the area is dominated by two major hydrogeochemical facies (i.e., Ca–Cl–SO₄ and Ca–HCO₃). Analysis of groundwater and river water quality index (GRWQI) elucidates that majority (82%) of samples are of “excellent” to “good” category, and the remaining 12% are of “poor” quality. Similarly, the effluent water quality index (EWQI) indicates that 6 out of 8 samples belong to excellent quality. Concentration of trace element constituents such as As, Zn, Cu, Cr, and Cd is found to be well within the stipulated limits for potable use, except for Fe, Mn, and Pb. Suitability of water samples for irrigation purpose, established using standard tools like Wilcox and USSL diagrams, reveal “excellent to permissible” category for majority of the samples. The present study also substantiates the effectiveness of the measures implemented for the treatment of mine effluent water.     

Salt-marsh tide pools as winter refuges for the mummichog,Fundulus heteroclitus,in New Jersey

Mummichog,Fundulus heteroclitus, were collected weekly from a southern New Jersey high-salinity salt marsh from October 1988 to June 1989 and from September 1989 to June 1990 to determine the overwintering habitat. Major habitat types sampled within the salt marsh were subtidal creek, intertidal creeks, and salt-marsh pools. Few individuals were collected in the intertidal creek or the subtidal creek from the end of October through the beginning of May for both years, when creek water temperatures were low. Both young-of-the-year and adults of both sexes were abundant in the salt-marsh pools (total lengths ranged from 29 mm to 125 mm) throughout the winter. In the spring, catch per unit effort (CPUE) within the tidal creek increased with increasing water temperature, while CPUE in marsh pools decreased with increases in estuarine water temperature. These collection patterns indicate that the majority ofF. heteroclitus may move from subtidal and intertidal creeks into salt-marsh pools in the late fall and leave in the spring. This seasonal movement could explain how fish survive winter environmental conditions because daily average water temperatures of salt-marsh pools were warmer than subtidal creek temperatures for much of the winter.     

Oligohaline benthic invertebrate communities at two Chesapeake Bay power plants

Benthic invertebrate populations at the Surry power plant on James River, Virginia and the C. P. Crane power plant on Saltpeter Creek, Maryland exhibited large spatial and temporal variations. At C. P. Crane, where the cooling water is pumped between two tidal creeks, populations in the receiving creek exhibited five response patterns: 1) mitigation of a winter dieoff (Rangia cuneata, a brackish water clam), 2) acceleration of growth or development (R. cuneata; Scolecolepides viridis, a polychaete;Leptocheirus plumulosus, an amphipod; Tubificidae; andCoelotanypus sp., a dipteran), 3) importantion of larvae from the source water creek (S. viridis andCoelotanypus sp.), 4) extension of creek-dwelling species into the adjacent river (Coelotanypus sp. and other dipterans), and 5) increased severity of late summer population depressions (S. viridis andL. plumulosus). At Surry, where the cooling was no confined creek system at the discharge, and effects were less pronounced. The community in the Surry discharge zone resembled the community at downriver stations more closely than at upriver reference stations. TheL. plumulosus population near the Surry discharge was depressed, while theMytilopsis leucophaeta population was enhanced. No major ecological damage was attributed to either power plant, due in part to the resilience of estuarine endemic populations, but the unique features exhibited by each of the two sites support the argument that oligohaline estuarine zones should not be designateda priori for unregulated industrial development.     

Hydrochemical characteristics of groundwater and surface water for domestic and irrigation purposes in Vea catchment,Northern Ghana

The Vea catchment, mainly underlain by crystalline basement rocks, is located in Northern Ghana. Hydrogeochemical studies were carried out in this area with the objective of identifying the geochemical processes influencing water quality and suitability of surface and groundwater for agricultural and domestic uses. Sixty-one groundwater and four surface water samples were collected from boreholes, dams and rivers and analysed for Ca²⁺, Mg²⁺, Na⁺, K⁺, HCO₃ ^?, Cl^?, and SO₄ ^2?, Fe_tot, PO₄ ^3?, Mn_tot, NH₄ ⁺, NO₃ ^?, NO₂ ^?. In addition, pH, total dissolved solids, electrical conductivity, total hardness, turbidity, colour, salinity and dissolved oxygen were analysed. Chloro-alkaline indices 1 and 2, and characterization of weathering processes suggest that the chemistry of groundwater is dominated by the interaction between water and rocks. Cation exchange and silicate weathering are the dominant processes controlling the chemical composition of the groundwater in the area studied. Mineral saturation indices indicate the presence of at least three groups of groundwater in the Vea catchment with respect to residence time. The meteoric genesis index suggests that 86% of the water samples belong to the shallow meteoric water percolation type. The findings further suggest that the groundwater and surface water in the basin studied are mainly Ca–Mg–HCO₃ water type, regardless of the geology. Compared to the water quality guidelines of WHO, the study results on sodium absorption ratio, sodium percentage, magnesium hazard, permeability index and residual sodium carbonate indicate that groundwater and surface water in the Vea catchment are generally suitable for drinking and irrigation purposes.     

Effects of stormwater nutrient discharges on eutrophication processes in nearshore waters of the Florida keys

Rainfall events cause episodic discharges of groundwaters contaminated with septic tank effluent into nearshore waters of the Florida keys, enhancing eutrophication in sensitive coral reef communities. Our study characterized the effects of stormwater discharges by continuously (30-min intervals) measuring salinity, temperature, tidal stage, and dissolved oxygen (DO) along an offshore eutrophication gradient prior to and following heavy rainfall at the beginning of the 1992 rainy season. The gradient included stations at a developed canal system (PP) on Big Pine Key, a seagrass meadow in a tidal channel (PC), a nearshore patch reef (PR), a bank reef at Looe Key National Marine Sanctuary (LK), and a blue water station (BW) approximately 9 km off of Big PIne Key. Water samples were collected at weekly intervals during this period to determine concentrations of total nitrogen (TN), ammonium (NH₄ ⁺), nitrate plus nitrite NO₃ ^? plus NO₂ ^?), total phosphorus (TP), total dissolved phosphorus (TDP), soluble reactive phosphorus (SRP), and chlorophyll a (chl a). Decreased salinity immediately followed the first major rainfall at Big Pine Key, which was followed by anoxia (DO <0.1 mg I^?1), high concentrations of NH₄ ⁺ (≈24 μM), TDP (≈1.5 μM), and chl a (≈20 μg I^?1). Maximum concentration of TDP (≈0.30 μM) also followed the initial rainfall at the PC, PR, and LK stations. In contrast, NH₄ ⁺ (≈4.0 μM) and chl a (0.45 μg I^?1) lagged the rain event by 1–3 wk, depending on distance from shore. The highest and most variable concentrations of NH₄ ⁺, TDP, and chl a occurred at PP, and all nutrient parameters correlated positively with rainfall. DO at all stations was positively correlated with tide and salinity and the lowest values occurred during low tide and low salinity (high rainfall) periods. Hypoxia (DO <2.5 mg I^?1) was observed at all stations follwing the stormwater discharges, including the offshore bank reef station LK. Our study demonstrated that high frequency (daily) sampling is necessary to track the effects of episodic rainfall events on water quality and that such effects can be detected at considerable distances (12 km) from shore. The low levels of DO and high levels of nutrients and chl a in coastal waters of the Florida Keys demand that special precautions be exercised in the treatment and discharge of wastewaters and land-based runoff in order to preserve sensitive coral reef communities.     

Efficiency assessment of aerobic biological effluent treatment plant treating pharmaceutical effluents

The present paper undertakes a study of the physico-chemical properties and toxic heavy metals content in the untreated and treated pharmaceutical effluents in order to evaluate the working efficiency of industrial effluent treatment plants. The treatment efficiency achieved for various parameters was conductivity (79.94%), alkalinity (93.91%), hardness (87.70%), chloride (89.24%), cyanide (79.66%), phosphate (99.19%), total dissolved solids (85.89%), total suspended solids (96.87%), salinity (52.41%), dissolved oxygen (27.32%), biochemical oxygen demand (83.39%) and chemical oxygen demand (72.21%). The removal efficiency achieved for different heavy metals was Cu²⁺ (79.66%), Ni²⁺ (69.22%), Cr⁶⁺ (80.15%), Pb²⁺ (72.14%), Fe³⁺ (92.59%) and Zn²⁺ (90.61%). The level of biochemical oxygen demand (64 mg L^?1) in the treated effluents was above the limit of 30.0 mg L^?1, chemical oxygen demand level (208 mg L^?1) was close to a limit of 250 mg L^?1, while average Pb²⁺ concentration (0.10 mg L^?1) was on the borderline of maximum permissible limit of 0.10 mg L^?1 set by Central Pollution Control Board for safe discharge of industrial effluent in inland surface water. The average concentration of cyanide (0.01 mg L^?1) in the treated industrial effluent of our study is of great concern to the fisheries of freshwater ecosystem in which the effluents finally get discharged. Based on the results of the present study, it is concluded that the pollution level in the discharged pharmaceutical effluent is of the great concern requiring proper treatment and regular scientific monitoring so as to protect the environmental degradation of water resources and facilitate the propagation of the aquatic life.