An appraisal of subsurface geology and groundwater resources of Owerri and environs based on electrical resistivity survey and borehole data evaluation

The research was aimed at determining the depth to the watertable, aquifer thickness and subsurface geology of the studyarea thus revealing its groundwater distribution as well as its potential as a substitute to the surface water resources.Vertical electrical soundings were carried out in the study area with maximum electrode spread. The Schlumberger electrode configuration technique was adopted. VES data were processedusing Schlumberger analysis package. Lithologic logs of alreadyexisting boreholes in the study area were collected, evaluatedand comparison were carried out. The results reveal alternatinglayers of sands, sandstones, gravel and clay. The lithologiclogs revealed that the study area is underlain by coastal sands (Benin formation). The water table varies from 10–64 m and thickness of the aquifer ranges from 20–80 m. Results show that the study area is underlain by a thick extensive aquifer that has a transmissivity of 2.8 × 10^-2m² s^-1 to 3.3 × 10^-1m² s^-1 and storativity 1.44 × 10^-4 to 1.68 × 10^-3m s^-1 values. The specific yield is about 0.31.The sandy component of the study area forms more than 90% ofthe sequence, therefore the permeability, the transmissivity andthe storage coefficient are high with an excellent source of groundwater resources.     

Use of microbial activity measurements for monitoring RBC biofilms

Fixed biomass technologies, such as rotating biological contactors or biodiscs, have been applied for wastewater depuration both in large and medium–small-sized agglomerations. Biofilm’s composition and microorganism activity are essential parameters for the successful operation and control of these systems. Biofilm’s thickness and total dry weight have been widely used for biofilm’s characterization but, actually, are not sufficient to describe biofilm activity. In fact, biofilm’s activity is not proportional to the quantity of fixed biomass, but increases with the thickness of biofilm up to a determined level called the “active thickness”. Above this level, the diffusion of nutrients through the film becomes a limiting factor. A stable, thin, and active biofilm thus offers numerous advantages in water and wastewater treatment. Different parameters have been used to evaluate biofilm’s activity. The specific oxygen uptake rate, INT-dehydrogenase activity, and the ratio active/total cells have been applied for that purpose. These methods are not only simple and rapid but also sensitive, precise, and representative. The results obtained confirm the potential of the microbial activity measurements studied for an accurate biofilm’s characterization and biomass activity estimation in fundamental research and for the practical operation and control of fixed biomass depuration systems.     

Biofilm thickness measurement using an ultrasound method in a liquid phase

In this report, the development of an online, noninvasive, measurement method of the biofilm thickness in a liquid phase is presented. The method is based in the analysis of the ultrasound wave pulse-echo behavior in a liquid phase reproducing the real reactor conditions. It does not imply the removal of the biomass from the support or any kind of intervention in the support (pipes) to detect and perform the measurements (non-invasiveness). The developed method allows for its sensor to be easily and quickly mounted and unmounted in any location along a pipe or reactor wall. Finally, this method is an important innovation because it allows the thickness measurement of a biofilm, in liquid phase conditions that can be used in monitoring programs, to help in scheduling cleaning actions to remove the unwanted biofilm, in several application areas, namely in potable water supply pipes.     

Transient modeling of trickling filters for biological ammonia removal

A dynamic model for nitrifying trickling filters is developed, based on material balances in the biofilm and the bulk liquid. The model predicts the profile of ammonia as a function of the operating parameters (volumetric flow rate and feed ammonia concentration) and the biofilm thickness as a function of filter depth and time. This revised version was published online in July 2006 with corrections to the Cover Date.     

Biomonitoring in the Boulder River Watershed, Montana, USA: Metal Concentrations in Biofilm and Macroinvertebrates, and Relations with Macroinvertebrate Assemblage

Portions of the Boulder River watershed contain elevated concentrations of arsenic, cadmium, copper, lead, and zinc in water, sediment, and biota. We measured concentrations of As, Cd, Cu, Pb, and Zn in biofilm and macroinvertebrates, and assessed macroinvertebrate assemblage and aquatic habitat with the objective of monitoring planned remediation efforts. Concentrations of metals were generally higher in downstream sites compared with upstream or reference sites, and two sites contained metal concentrations in macroinvertebrates greater than values reported to reduce health and survival of resident trout. Macroinvertebrate assemblage was correlated with metal concentrations in biofilm and macroinvertebrates. However, macroinvertebrate metrics were significantly correlated with a greater number of biofilm metals (8) than metals in invertebrates (4). Lead concentrations in biofilm appeared to have the most significant impact on macroinvertebrate assemblage. Metal concentrations in macroinvertebrates were directly proportional to concentrations in biofilm, indicating biofilm as a potential surrogate for monitoring metal impacts in aquatic systems.     

Zoning for eco-geological environment before mining in Yushenfu mining area,northern Shaanxi,China

Zoning for the eco-geological environment (EGE) aims to protect and improve the regional ecological environment. It is the basis for evaluating the ecological characteristics of a mining area prior to mining activities and has the purpose of implementing water-preserved mining according to zoning type. In this study, four EGE types were proposed following field investigation in the Yushenfu mining area: oasis type with phreatic water and bottomland in desert (OTPWBD), oasis type with surface water and valley river (OTSWVR), loess gully type with surface runoff (LGTSR), and regional deep groundwater enrichment type (RDGET). Nine EGE evaluation indices were selected: rainfall, evaporation capacity, Luohe formation thickness, surface elevation, Sara Wusu aquifer water abundance, surface lithology, topography, slope, and normalized difference vegetation index (NDVI). Remote sensing technology and geographic information systems were first used to generate the evaluation index thematic maps. Then, the weight of each evaluation index was determined based on an analytic hierarchy process (AHP). Third, the index weight was used to form an improved weighted fuzzy C s clustering algorithm, and EGE zones were assigned using the MATLAB computing platform. For comparison, the AHP was also adopted for EGE zoning and a map of zoning differences was obtained. Finally, EGE field surveys of typical mines were carried out, which verified that EGE zoning using fuzzy clustering was accurate and reasonable.     

Geochemical survey of an illegal waste disposal site under a waste emergency scenario (Northwest Naples, Italy)

Since the mid 1980s, Naples and the Campania region have suffered from the dumping of wastes into overfilled landfills. The aim was to characterise a former cave located in Roccarainola (Naples, Italy) for its eventual destination to a controlled landfill site. A detailed hydro-geochemical survey of the area was carried out through drilling of 14 boreholes and four monitoring wells. Samples of water, sediment and soil were analysed for heavy metals and organic contaminants from a dew pond placed in the middle of the cave. The underneath aquifer was also surveyed. The nature of gases emitted from the site was investigated. Results of the geognostic survey revealed the presence of huge volumes of composite wastes, approximately half a million of cubic metre, which accumulated up to a thickness of 25.6 m. In some points, wastes lie below the free surface level of the aquifer. The sampled material from the boreholes revealed levels of As, Cd, Cr, Cu, Hg, Pb, Sn, Tl and Zn exceeding the intervention legal limits. Outstanding loads of Cd, Pb and Zn were found, with levels exceeding of about 50, 100 and 1,870 times the limit. In several points, polycyclic aromatic hydrocarbon load was extremely high, 35 vs 1 mg kg^?1 of the threshold. The aquifer was also very heavily polluted by Cd, Cr-tot, Cu, Fe, Mn, Ni, Pb and Zn, with impressive high load of Cr and Mn, up to 250–370 times the limits. Hot gases up to 62 °C with presence of xylene and ethylbenzene were found. Results indicated that the site needs an urgent intervention of recovery to avoid compromising the surrounding areas and aquifers of the Campania plain.     

Operational and Design Considerations of a Trickling Filter for Ammonia Removal from Potable Water

We studied the steady-state behavior of a mathematical model of a nitrifying trickling filter. In particular, we studied the effect of the operating conditions of the filter on the complete and safe nitrification. We presented the results with the help of the operating diagram of the system and we determined the range of operating conditions resulting in optimal operation. We also computed biofilm thickness along the filter depth and concentration profiles inside the biofilm, and compared them with experimental results found in the literature. The comparison shows very good qualitative agreement between model predictions and experimental data.     

Impacts of restoration of an uncontrolled phosphogypsum dumpsite on the seasonal distribution of abiotic variables, phytoplankton, copepods, and ciliates in a man-made solar saltern

The restoration of an uncontrolled phosphogypsum landfill was investigated for its effects on the seasonal distribution of phytoplankton, ciliates, and copepods. Sampling was carried out monthly from September 2007 to August 2008 at four ponds of increasing salinity (A1, 41 psu; A5, 46 psu; A16, 67 psu; and C31, 77 psu) in the Sfax solar saltern (southeastern Tunisia). Physicochemical and biological analyses were carried out using standard methods. Results showed drastic reduction of phosphate input and greater diversity of phytoplankton, ciliates, and copepods than before restoration. Pennate diatoms and new ciliates, considered bio-indicators of less-stressed marine ecosystems, proliferated in the A1 pond for the first time after restoration. Copepods appeared to feed on a wide range of prey. Economically, removal of the 1.7 million m³ of phosphate improved the quality of the site’s salt production, enabling the salt company to receive the quality ISO 9001 accreditation.     

Development and application of microwave assisted extraction (MAE) for the extraction of five polycyclic aromatic hydrocarbons in sediment samples in Johannesburg area, South Africa

A microwave-assisted extraction (MAE) method was verified and applied for the extraction of polycyclic aromatic hydrocarbons (PAHs) in sediment samples. Soxhlet extraction was used as the reference method. The optimum MAE was carried out with 20 mL of hexane/acetone (1:1, v/v) mixture in a 1-g sample at 250 W for 20 min. Soxhlet extraction was carried out with 250 mL of dichloromethane:hexane (1:1, v/v) mixture in a 15-g sample for 24 h in a water bath maintained at 60 °C. The collected extracts were both cleaned up, reduced to 1 mL under nitrogen and then injected into an HPLC fluorescence. To increase the sample throughput, simultaneous MAE was performed. The obtained percentage recoveries ranged from 61 to 93 and 88–98 for MAE and SE, respectively. The optimised MAE method was validated using certified reference material. It was then applied to real sediment samples from in and around the greater Johannesburg area. The sediments from Jukskei River were found to be the most polluted while Hartbeespoort Dam sediments were found to be least polluted. The overall order of concentrations for the studied PAHs per site was as follows: Jukskei River?>?Kempton Park?>?Centurion Dams?>?Natalspruit River (PIT)?>?Hartbeespoort Dam.     

Endocrine disruption effects of 2,2',4,4',6-pentabromodiphenylether (BDE100) in reporter gene assays

Polybrominated diphenyl ethers (PBDEs) constitute an important group of flame retardants. 2,2',4,4',6-Pentabromodiphenylether (BDE100) is a prominent PBDE congener in some human populations. The potential of BDE100 to modulate responses mediated by the estrogen (ER), thyroid hormone (ThR) or androgen receptors (AR) were investigated by use of transactivation reporter gene assays. The African green monkey kidney CV-1 cell transiently transfected with the constructed reporter gene plasmid ERE-TATA-Luc and pUAS-tk-Luc with luciferase (Luc) under control of the estrogen response (ERE), or thyroid hormone response (ThRE) elements were used to evaluate (anti)estrogen and thyroid effects of BDE100. The (anti)androgenic potency of BDE100 was also evaluated by use of MDA-kb2 cells, which were stably transfected with MMTV-luciferase. The assays displayed appropriate responses to known natural estrogen 17β-estradiol (E2), ThR ligand triiodothyronine (T3), and the AR agonist 5α-dihydrotestosterone (DHT). 10 or 50 μM BDE100 significantly up-regulated expression of Luc under control of the ER. Antiestrogenic potency was observed for BDE100 (IC50 = 6.21 μM). Co-exposure to 50 μM BDE100 significantly enhanced expression of Luc caused by 5 nM T3. BDE100 was antiandrogenic at 10 and 50 μM with an IC50 of 28.60 μM BDE100. These results suggest that BDE100 can modulate the endocrine system in multiple ways by interfering with several hormonal signaling pathways simultaneously.     

Constructed wetlands using aluminium-based drinking water treatment sludge as P-removing substrate: should aluminium release be a concern?

This study investigated an important issue of aluminium (Al) release from a novel reuse of Al-based water treatment sludge (Al-WTS) in constructed wetland system (CWs) as alternative substrate for wastewater treatment. Al-WTS is an inevitable by-product of drinking water treatment plants that use Al-salt as coagulant for raw water purification. It has recently been demonstrated that Al-WTS can be reused as a low-cost phosphorus (P) adsorbent and biofilm carrier in CWs for wastewater treatment. However, to facilitate the large scale application of Al-WTS in CWs as wetland substrate, concerns about Al leaching during its reuse in CWs must be addressed as Al is a dominant constituent in Al-WTS. In this study, a desk review of literature on Al release during Al-WTS reuse was conducted. Furthermore, a 42-week Al monitoring was carried out on a pilot field-scale CWs employing Al-WTS as main substrate. Results show that 22 out of the 35 studies reviewed, reported Al release with levels of soluble Al reported ranging from 0.01 to about 20 mg L(-1). Monitoring of Al in the pilot field-scale CWs shows that there was Al leaching. However, except for the first three weeks of operation, effluents concentrations of both total- and soluble-Al were all below the general regulatory guideline limit of 0.2 mg L(-1). Overall, the study addresses a vital concern regarding the successful application of Al-WTS in CWs and shows that Al release during such novel reuse is quite low and should not preclude its use.     

Monitoring dioxins and furans in the vicinity of an old municipal waste incinerator after pronounced reductions of the atmospheric emissions

In order to get an overall picture of the environmental impact of an old municipal solid waste incinerator (MSWI) from S. Adrià del Besòs (Barcelona, Catalonia, Spain), a monitoring program addressed at determining the levels of a number of pollutants in the vicinity of the facility was initiated in 1998. In March 1999, an adaptation was carried out due to EU legislation on pollutant emissions from the stack. As a result, emissions of polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) were notably reduced, and a significant (30%) decrease was found in the levels of PCDD/F in herbage samples collected in the vicinity of the MSWI. In March 2001, herbage samples were collected at the same sampling points and the PCDD/F levels measured again. The current PCDD/F concentrations range from 0.23 to 1.43 ng I-TEQ kg(-1) (dry matter), with median and mean values of 0.58 and 0.66 ng I-TEQ kg(-1) (dry matter), respectively, while in the 2000 survey the PCDD/F concentrations ranged from 0.22 to 1.20 ng I-TEQ kg(-1) (dry matter), with median and mean values of 0.57 and 0.61 ng I-TEQ kg(-1) (dry matter), respectively. Although the current PCDD/F concentrations in herbage samples are comparable to those found in recent surveys carried out in various places of Catalonia, an exhaustive evaluation of the data, including principal component analysis, indicates that other emission sources of PCDD/Fs also have a notable environmental impact on the area under direct influence of the MSWI.     

Monitoring the impact of dissolved oxygen and nitrite on anoxic biofilm in continuous denitrification process

An anoxic biofilm involved in continuous denitrificationprocess was monitored to investigate the effect of differentconcentrations of influent dissolved oxygen (DO) or nitrite onthe biofilm. Microelectrode measurements evidenced nitrateremoval activity of biofilm. When different concentrations ofDO were applied to the reactor, generally decreasedconcentrations of DO were observed as bed depth increased fromthe bottom of the reactor. Greatest decrease of the DO wasobserved in the lower 20% of the bed depth. Nitrate removalefficiency was inversely proportional to influent DOconcentrations (8.3-11.9 DO mg L^-1) or nitrite loadingrates (0-5.5 N-NO₂ ^- kg m^-3 day^-1) employed in this study. Nitrite loading rates to achieve morethan 90% of nitrate removal efficiency were 1.46 N-NO₂ ^-kg m^-3 day^-1 or less at pH 7.5 and 0.34 N-NO₂ ^- kg m^-3 day^-1 or less at pH 6.8. Nitrate removal efficiency was 63% or more within the lower 20% of the bed depth at the nitrite loading rates that allowed more than 90% of nitrate removal efficiency of the reactor. The results of this study provide first quantitative data that nitrate removalperformance of an anoxic biofilm is inhibited by DO or nitrite,reported to be a limiting factor in the suspended biologicaldenitrification process.     

Genotoxic effects of water pollution on two fish species living in Karasu River,Erzurum, Turkey

Karasu River, which is the only river in the Erzurum plain, is the source of the Euphrates River (Eastern Anatolia of Turkey). The river is in a serious environmental situation as a result of pollution by agricultural and industrial sewage and domestic discharges. The present study aims to evaluate genotoxic effects of toxic metals in chub, Leuciscus cephalus, and transcaucasian barb, Capoeta capoeta, collected from contaminated site of the Karasu River, in comparison with fish from an unpolluted reference site. Heavy metal concentrations in surface water of the river were determined. The condition factor (CF) was taken as a general biomarker of the health of the fish, and genotoxicity assays such as micronucleus (MN) and other nuclear abnormalities (NA) were carried out on the fish species studied. MN and NA such as kidney-shaped nucleus, notched nucleus, binucleated, lobed nucleus, and blebbed nucleus were assessed in peripheral blood erythrocytes, gill epithelial cells, and liver cells of the fish. A significant decrease in CF values associated with a significant elevation in MN and NA frequencies was observed in fish collected from the polluted sites compared with those from the reference site. Results of the current study show the significance of integrating a set of biomarkers to identify the effects of anthropogenic pollution. High concentrations of heavy metals have a potential genotoxic effects, and the toxicity is possibly related to industrial, agricultural, and domestic activities.     

Monitoring and assessing variation of sewage quality and microbial functional groups in a trunk sewer line

In this study, the variation of sewage quality was investigated and the active fraction of different microbial functional groups in biofilm was quantified in a 5.6-km trunk sewer line. The sewage quality including suspended solids, biochemical oxygen demand, total chemical oxygen demand (COD), total nitrogen, total Kjeldahl nitrogen, ammonia nitrogen, nitrite nitrogen, and nitrate nitrogen were measured and compared with the values in literatures. The results indicated that since the wastewater treatment plant was not operated at its full capacity, the concentrations of different compounds were lower compared with the values in literatures. The values of heterotrophic growth rate constant lay between 5.6 and 8.6 day^???1. Its average value was 7.7 day^???1. The values of heterotrophic lysis rate constant lay between 0.2 and 0.4 day^???1. The active heterotrophic biomass in biofilm varied from 240 to 800 mg COD m^???2 and average value was 497 mg COD m^???2. The biofilm mass varied from 880 to 1,080 mg m^???2. The percentage of heterotroph to biofilm mass fall within the range of 24.0–90.9% and average value was 52.9%. In the oxygen uptake rate batch tests, the biomass, growth rate constant, and lysis rate constant of autotroph could not be determined because the fraction of autotroph in biofilm was relatively few. It revealed that the degradation of organic matters, nitrification, and denitrification occurred in the trunk sewer line. But the results indicate that the condition seem favorable for nitrification.     

Solid phase extraction of Cd,Pb, Ni,Cu, and Zn in environmental samples on multiwalled carbon nanotubes

A simple and sensitive solid phase extraction (SPE) method on multiwalled carbon nanotubes (MWCNTs) is presented for the determination of cadmium, lead, nickel, copper, and zinc at trace levels combined with flame atomic absorption spectrometry. The effects of parameters like pH, sample volume, sample and eluent flow rates, eluent concentration, and volume and type of eluent on the recovery of trace elements was examined. The metals retained on the nanotube at pH 6.5 as α-benzoin oxime complexes were eluted by 10 mL 2 M HNO₃ in acetone. The influence of matrix ions on the developed method was also evaluated. The preconcentration factor of the method was found to be 50. The detection limits for Cd(II), Pb(II), Ni(II), Cu(II), and Zn(II) were found as 1.7, 5.5, 6.0, 2.3, and 2.4 μg L^?1, respectively. To test the accuracy of the method, the method was applied to TMDA-70 fortified lake water and Spinach 1570A standard reference materials. Addition recovery studies were applied to tap water and cracked wheat samples, and determination of the analyte elements was carried out in some food samples with good results.     

Antimony: a traffic-related element in the atmosphere of Buenos Aires, Argentina

Vehicular traffic is one of the main sources of antimony in highly populated urban areas like Buenos Aires where an overall traffic density of 1 500 000 vehicles per day (corresponding to 7500 vehicles km(-2)) is estimated. In this context, a study was undertaken to ascertain the levels of Sb and other traffic-related elements (TRE) in the atmosphere of this city. To this end, sixty-seven samples of PM-10 particulate matter were collected during eight days in nine representative sampling sites located downtown Buenos Aires and spread over an area of about 30 km2. The collection of particulate matter was performed on ash-free glass-fibre filters using high volume samplers with PM-10 sampling heads. A combination of aqua regia and perchloric acid was used for leaching metals from filters. The resulting solutions were evaporated and then diluted with 0.1 mol l(-1) HCl. Antimony was determined by inductively coupled plasma-quadrupole mass spectrometry (ICP-QMS) at ng g(-1) levels. Concentrations of Sb varied from 12.9 +/- 0.9 to 375 +/- 23 microg g(-1)(equivalent to 0.87 +/- 0.06 to 15.3 +/- 0.8 ng m(-3)). Statistical analysis was performed on the data set including the measured PM-10 mass and Sb concentrations for the monitored period. Correlations of Sb with other TRE namely, Cu and Mo were also assessed. The highest concentrations of Sb were detected at two sites (Hospital Alemán and Casa Rapallini) located in streets with traffic consisting mostly of passenger cars and showing a "stop-and-go" pattern in peak hours. Antimony levels in the Buenos Aires PM-10 are by far below the level of 0.5 mg m(-3)(for an 8 hour workday, 40 hour work week) set by the US Occupational Safety and Health Administration (OSHA) for occupational exposure. However, monitoring of Sb and other TRE should be carried out in a systematic fashion to detect the possibility of increases in from the present levels.