The chemical dynamics at Meio Stream Basin, São Paulo State, Brazil were evaluated using major elements as natural tracers. The surface water samples from Meio Stream were collected near the mouth of Meio Stream at the confluence with the Mogi-Guaçu River on February 25, 2005, April 20, 2005, and July 8, 2005. Rainwater samples were collected (using a “bulk” collector) for 1 year at one sampling point located about 4 km from downtown Leme city and other possible sources of contamination. The analyses were performed by pH, temperature, dissolved oxygen, electrical conductivity, total solids, sulfate, nitrate, phosphate, alkalinity, chloride, sodium, calcium, potassium, and magnesium. This basin has serious environmental problems in terms of rainwater and surface water quality, which result in the negative annual flux of cations and anions at Meio Stream Basin, with the exception of chlorine. The Meio Stream, downstream from Leme city, receives several elements/compounds through anthropogenic activities, mainly related to the discharge of domestic effluents. Anthropogenic inputs (mining, fossil fuel burning, and agricultural activities) are responsible for the higher concentrations of cations and anions in the rainwater from this basin.

This study has investigated how to simultaneously remove both heavy metals (Cu, Mn, and Zn) and natural organic matters (NOM; humic acid and fulvic acid) from river water using potassium ferrate (K₂FeO₄), a multipurpose chemical acting as oxidant, disinfectant, and coagulant. In water sample including each 0.1 mM heavy metal, its removal efficiency ranged 28-99% for Cu, 22-73% for Mn, and 18-100% for Zn at the ferrate(VI) doses of 0.03-0.7 mM (as Fe). The removal efficiency of each heavy metal increased with increasing pH, whereas an overall temperature did not make any special effect on the reaction between the heavy metal and ferrate(VI). A high efficiency was achieved on the simultaneous treatment of heavy metals (0.1 mM) and NOM (10 mg/l) at the ferrate(VI) doses of 0.03-0.7 mM (as Fe): 87-100% (Cu), 31-81% (Mn), 11-100% (Zn), and 33-86% (NOM). In the single heavy metal solution, the optimum ferrate dose for treating 0.1 mM Cu or Mn was 0.1 mM (as Fe), while that for treating 0.1 mM Zn was 0.3 mM (as Fe). In the mixture of three heavy metals and NOM, on the other hand, 0.5 mM (as Fe) ferrate(VI) was determined as an optimum dose for removing both 0.1 mM heavy metals (Cu, Mn, and Zn) and 10 mg/l NOM. Prior to the addition of ferrate(VI) into the solution of heavy metals and NOM (HA or FA), complexes were formed by the reaction between divalent cations of heavy metals and negatively charged functional groups of NOM, enhancing the removal of both heavy metals and NOM by ferrate(VI).

Considering the importance of the oral route for human exposure to atrazine, we have investigated the possible effect of this herbicide on the human intestinal cells and the integrity of the epithelial barrier, using Caco-2 cells as the intestinal model in vitro. We evaluated possibile cytotoxic and genotoxic effects of atrazine in concentrations ranging from 1 to 250 μM on the Caco-2 cells at different stages of growth after short- and long-term exposure. Results from the tetrazolium blue (MTT) test and the Trypan blue exclusion assay showed that atrazine cytotoxicity was dose- and time-dependent. Obtained data indicated that atrazine at high concentrations (50 and 250 μM) was able to induce effects on Caco-2 proliferation and viability. Moreover, it was found that the long-term exposure to atrazine at the non-cytotoxic dose caused inhibition of the intestinal cell maturation and decreased the transepithelial electrical resistance, the indicator of the epithelial barrier integrity. Studies on the atrazine genotoxicity determined using the single cell microelectrophoresis assay indicated that atrazine did not induce DNA damages in the Caco-2 cells at concentrations of up to 50 μM, whereas enhancement in the DNA damage was observed at 250 μM. Altogether, our results indicate that atrazine at expected human oral exposure concentrations is not able to induce effects on the Caco-2 cell proliferation and viability, but may suppress the intestinal cell differentiation and reduce the cell monolayer integrity. We suggest that chronic exposure on low levels of atrazine may lead to alteration in the expression of the morphological and functional features of the Caco-2 cells related to the transport and barrier function of small intestinal enterocytes. In consequence, this may lead to alterations in the intestinal absorption process.

The feasibility of using recycled granular tire rubber (GTR) to remove molinate from contaminated water bodies was evaluated in this study. Adsorption equilibrium data was well described by a linear isotherm, and the adsorption was completely reversible. Breakthrough curves showed column efficiencies of approximately 40%, based on total capacity, and complete bed regeneration was achieved using clean water. The effluent from the regeneration step was successfully decontaminated using a defined bacterial mixed culture, capable of molinate mineralization. It was shown that this treated water can be used for regenerating a subsequently saturated bed. The GTR adsorbent showed two important features: complete reversibility towards molinate adsorption and stability along successive adsorption/bio-regeneration cycles. Common adsorbents, such as activated carbons and resins, loose performance very quickly under the same conditions, due to irreversible adsorption.

A strong base anion exchange resin Amberlite IRA-400 Cl⁻ and its hybrids with Mn(OH)₂ and Cu(OH)₂ are used for the removal of chromium from the synthetic spent tannery bath. The recovery is examined by varying the experimental conditions, viz., resin dosage, stirring speed, and temperature. The rate of chromium removal by Amberlite IRA-400 Cl⁻ increased almost four times when the resin dosage was increased from 0.2 to 1.0 g. Furthermore, the rate of chromium sorption almost doubled when the stirring speed was increased from 100 to 1,000 rpm, suggesting that the sorption is a diffusionally controlled process. The chromium removal capacity also increased with the rise of temperature, showing the endothermic nature of the process. The results are explained with the help of film diffusion, particle diffusion, and Lagergren pseudo-first-order kinetic models. The kinetics results of the Amberlite IRA-400 Cl⁻ are compared with its hybrid anion exchange resins IRA-400 Mn(OH)₂ and IRA-400 Cu(OH)₂. It is found that the hybrid ion exchangers have greater removal ability and fast kinetics as compared to the parent exchanger.

This study was carried out to assess the overall water quality and identify major variables affecting the deep groundwater quality in Kathmandu Valley, Nepal. Forty-two deep wells were sampled during premonsoon and monsoon seasons in 2007 and analyzed for the major physicochemical variables. The water quality variables such as NH ₄ ⁺ -N, Fe, Pb, As, and Cd at most of the sampling locations exceeded the World Health Organization guideline levels for drinking water. Multivariate statistical techniques such as factor analysis and cluster analysis were applied to identify the major factors (variables) corresponding to the different source of variation in deep groundwater quality. Factor analysis indentified six major factors explaining 74.77% of the total variance in water quality; and the major variations are related with the degree of groundwater mineralization, decomposition of organic matter, and reduction of groundwater environment. The water quality of deep groundwater is influenced by the natural hydrogeochemical environment. The wells are broadly divided into two major groups based on the similar groundwater characteristics using cluster analysis. Results show that water quality of deep groundwater does not vary significantly as a function of season.

Linear anionic polyacrylamide (LA-PAM) is being considered as a soil amendment to reduce seepage and infiltration in unlined earthen canals. While polyacrylamides have been extensively used for potable water treatment, dewatering sewage sludge, coal and mine processing, paper manufacturing, and agriculture, little is known about its ecological impact to aquatic ecosystems. Acute toxicity (LC₅₀, 24 and 48 h) and chronic exposure tests (limited and continuous exposures) were conducted on Daphnia magna. In the chronic limited exposure experiments, Daphnia were exposed to LA-PAM for only 24 h whereas for the chronic continuous exposure the concentrations of 0, 0.5, 1, 5, 10, and 100 mg/L were tested and the endpoints of growth, onset to reproduction, fecundity, and mortality were measured for the duration of 32 days. There was no significant difference among the chronic, limitedly exposed organisms. The acute toxicity for LA-PAM was measured at 100, 150, 200, 250, and 300 mg/L. The acute test showed that the LC₅₀ for LA-PAM was at 152 mg/L. Overall in the chronic, continuous exposure test, D. magna was negatively impacted by LA-PAM at levels as low as 1 mg/L. Growth was reduced by 37% and 89% at 1 and 100 mg/L, respectively. Fecundity and onset to reproduction was impaired at 10 and 100 mg/L. Kinematic viscosity ranged from 0.98 cSt at 1 mg/L to 2.9 at 100 mg/L. At these levels, mechanical and physiological impairments due to the viscous properties of LA-PAM are the proposed mechanisms of reduction in the life history traits of D. magna.

We tested the efficacy of matrix-based fertilizers (MBFs) to improve Kentucky bluegrass (Poa pratensis L.) growth while reducing NH, NO3, dissolved reactive phosphorus (DRP), and total phosphorus (TP) compared to commercial slow-release fertilizer (SRF) Polyon®, ESN®, and Avail® in greenhouse column studies. The MBFs covered a range of inorganic N and P in compounds that are relatively loosely bound (MBF6) and more tightly bound compounds (MBF7) with Al(SO4)318H2O and/or Fe2(SO4)33H2O and with high ionic exchange compounds starch, cellulose, and lignin. The total amount of NO3 and NH4 leached was greater from columns receiving Polyon® and ESN® fertilizers than all other treatments. The MBF6+Avail® or MBF7+Avail® fertilizers leached 64–68% less NO3 than Polyon® (43-0-0) and ESN® (46-0-0), and 73–76% less TDP and TP than Avail® (10-34-0). A greater amount of NO3 was leached from the MBF6+Avail® and the MBF7+Avail® treatments than the other MBF fertilizer treatments. Shoot and root biomass were greater when plants received the Avail®, MBF6+Avail®, and MBF7+Avail® fertilizer treatments than the other fertilizer treatments. When combined with small quantities of commercial SRFs, these new MBFs were able to maintain plant growth while reducing N and P leaching. These new MBF formulations do not depend on organic or inorganic coatings to reduce N and P leaching and with further testing and development could be effective commercial fertilizers.

A study on pH and chemical composition of precipitation was carried out in two Italian sites, one urban (site 1) and one rural (site 2), located approximately 30 km far from Bologna, during a 3-year period. No significative site variation was found. In both locations, bulk deposition pH ranged from slightly acid to slightly alkaline, despite the volume weighted mean concentration of acidic species, NO ₃ ⁻ and SO ₄ ²⁻ (67.4 and 118.4 μeq l⁻¹ in site 1 and 88.7 and 103.8 μeq l⁻¹ in site 2), that were similar to those of typical acidic rainfall region. This might be ascribed to the neutralization reaction of the Ca²⁺, attributed to the calcareous soil and the frequent dusty air mass intrusion from the Sahara. The pair correlation matrix and the analysis of the main components suggested also ammonium and other crustal elements as neutralization agents. The depositional rate of SO ₄ ²⁻ and NO ₃ ⁻ , chemical elements of agricultural interest, amounted to 38 and 28 and 32 and 35 kg ha⁻¹ for site 1 and site 2, respectively. These supplies of nutrient were not negligible and had to be considered on cultivated lands. NH ₄ ⁺ deposition rate on site 2 was 7 kg ha⁻¹, 23% over site 1, probably due to nitrogen fertilization in the fields around the monitoring station. In site 1, SO ₄ ²⁻ presented a seasonal trend, indicating that its principal source was the residential heating. Results emphasized that the entity of the bulk deposition acidification is linked not only to the ions local emission sources (fossil fuel combustions, heating, and fertilizers) but also to the surrounding territory and the prevalent wind that transports through kilometers air masses which may contain acidic and alkaline species.

Thais gradata samples were collected from six locations along the southern shores of Peninsular Malaysia and analyzed for imposex incidence and organotin (butyltins (BTs), including tributyltin, dibutyltin, and monobutyltin, and phenyltins (PTs), including triphenyltin, diphenyltin, and monophenyltin concentrations), in tissue burden. On average, the BT levels were found to be higher than the levels reported a year before for other biota. In contrast, the PT compounds were found to be lower than in the previous report. The present study also classified the morphological expressions of the imposex scheme for this species into seven stages (stage 0 to stage 6) by observing the development of vas deference sequence (VDS) and penis bulk. This latest imposex scheme clearly indicates the mechanism of VDS growth, the structural changes from penis bulk to a penis with flagellum, and from a normal vaginal opening to a swollen vaginal opening. The degree of imposex was assessed using the vas deference sequence index and the percentage of females possessing the imposex characteristics. It was found that locations possessing high imposex levels also tended to show high BT levels in the snail tissue samples. However, correlation analysis did not show a significant relationship among the two parameters. A better result could be obtained if more samples and sampling locations were added in order to prove the hypothesis. The nonsignificant correlation between the shell height and any of the organotin compounds, along with no significant differences between BT levels in female and lower imposex stage samples, suggests that the BT concentration detected was a recent contamination.