Based on the fact that streamwater quality reflects landscape conditions, the objectives of this study were: to investigate nitrogen (N), carbon (C), and major ion concentrations in six streams crossing minimally disturbed Atlantic Forest areas, with similar geomorphological characteristics; to determine N and C fluxes in one of these pristine streams (Indaiá); and assess the impact of human activity on the biogeochemistry of two other streams in the same region, crossing urbanized areas. The distribution pattern of carbon and inorganic nitrogen dissolved forms, as well as the major ion and biogenic gas concentrations in the streamwater, was similar in pristine streams, indicating that the C and N dynamics were determined by influence of some factors, such as climate, atmospheric deposition, geology, soil type, and land covering, which were analogous in the forested watersheds. The urban streams were significantly different from the pristine streams, showing low dissolved oxygen concentrations, high respiration rates, and high concentrations of carbon dioxide, dissolved inorganic nitrogen, dissolved inorganic carbon, and major ion. These differences were attributed to anthropogenic impact on water quality, especially domestic sewage discharge. Additionally, in the Indaiá stream, it was possible to observe the importance of rainfall over temporal dynamics of dissolved carbon forms, and also, the obtained specific flux of dissolved inorganic nitrogen was relatively elevated (approximately 11 kg ha⁻¹ year⁻¹). These results reveal the influence of human activity over the biogeochemistry of coastal streams and also indicate the importance N export of Atlantic Forest to the ocean.

The aim of the present study was to estimate the geochemical background and anomaly threshold values of the surface soils in Kavala, northern Greece. In order to reach this goal, a simple and practical procedure was applied. This procedure included the extraction of 42 major and trace elements by analytical grade HNO3 from 65 surface soil samples, analysis by inductively coupled plasma–optical emission spectrometry and inductively coupled plasma–mass spectrometry, the distribution of the elemental data displayed on probability graphs (Q-Q plots), and the visualization of the results spatially by GIS software. The results indicated that natural factors mostly influence the elevated concentrations of Al, Ca, Fe, K, Mg, Si, B, Ba, Ce, Ga, Ge, La, Li, Mn Rb, Sb, Se, Sn, Sr, Y, and Zr, while anthropogenic activities mostly influence the elevated concentrations of Ag, As, Cd, Co, Cr, Cs, Cu, Hg, Mo, Ni, Pb, Th, Ti, U, V, W, and Zn. Nevertheless, almost all the elements determined showed their elevated concentrations inside the industrial part of Kavala area, which implies that the anthropogenic activities taking place in the study area, influence importantly the spatial distribution of the elements. The methodology followed in this research seems to be an adequate alternative for soil environmental studies.

The purpose of this study was to determine the impacts of regional historical uranium mining activities within sediments of the Bowman–Haley reservoir of southwestern North Dakota. The extent of anthropogenic-influenced watershed impacts were quantified through the determination of sediment metals concentrations and metal enrichment factors to evaluate the potential of geochemically influenced As and U remobilization within the reservoir sediments. Sediment cores were collected and analyzed for total metal concentrations at five locations within the reservoir: Spring Creek delta, Alkali Creek delta, two locations within the North Fork of the Grand River confluence, and adjacent to the reservoir outfall. Pearson-moment correlations were used to establish inter-core metal correlations, while sediment enrichment factors were determined relative to background concentrations. Enrichment factor results suggest all sampling sites are classified as minor to moderately enriched for As and U. Metal behavior for the three reservoir inlets indicated similar metal loading sources and post-depositional behavior, while metals migration within the vicinity of the reservoir outlet appear to be controlled by geochemical and/or physical processes. For the reservoir outlet, As and U normalized to Al suggest the occurrence of vertical migration of As, while surface-bound U remobilization was apparent within the water column immediately above the sediments. Elevated U was found within the Spring Creek inlet, and appear attributed to historical uranium processing operations located in Griffin, North Dakota. While the reservoir As and U sediment concentrations may be considered low, their presence appears directly attributed to historical uranium mining activities within the Bowman–Haley reservoir watershed.

The objective of this study is to develop a method for using the single-well natural gradient drift test (SWNGDT) in the field to assess in situ aerobic cometabolism of trichloroethylene (TCE) and to analyze microbial community changes. The SWNGDT was performed in a monitoring well installed in a TCE-contaminated aquifer in Wonju, South Korea. The natural gradient drift biostimulation test (NGDBT) and surrogate test (NGDST) were performed by injecting dissolved solutes (bromide (a tracer), toluene (a growth substrate), ethylene (a nontoxic surrogate substrate to probe for TCE transformation activity), dissolved oxygen (DO, an electron acceptor), and nitrate (nutrient)) into the aquifer. Push–pull blocking tests (PPBT) were also performed to examine whether the monooxygenase of toluene oxidizers is involved in the degradation of toluene and the transformation of ethylene. Through the NGDBT, NGDST, and PPBT, we confirmed that the addition of toluene and oxygen in these field tests stimulated indigenous toluene utilizers to cometabolize aerobically TCE, with the following results: (1) the observed simultaneous utilization of toluene and DO; (2) the transformation of ethylene to ethylene oxide and propylene to propylene oxide; and (3) the transformation of TCE. Furthermore, the results of restriction fragment length polymorphism suggested that the microbial community shifts and the microbes capable of transforming TCE are stimulated by injecting the growth substrate, toluene.

In this study, microalgae Scenedesmus quadricauda was entrapped in calcium alginate/polyvinyl alcohol composite hydrogel beads by phase-inversion techniques. The composite biosorbents were used for removal of Cu(II) and Cd(II) ions from single component and binary systems using cell-free composite beads as a control system. The effects of the experimental conditions (such as pH, initial metal ions concentrations, temperatures, contact time, and biosorbent concentrations) on Cu(II) and Cd(II) removal efficiencies were studied. The maximum metal ions on the bare and algal biomass immobilized in alginate beads were observed between pH 5.0 and 6.0. The biosorption of metal ions by the bare and composite beads increased as the initial concentration of the metal ions increased in the medium. The biosorption of Cu(II) and Cd(II) on the composite beads appears to be slightly temperature dependent. The maximum biosorptions of metal ions onto microalgae entrapped in composite beads were 0.970 ± 0.028 and 0.682 ± 0.017 mmol/g for Cu(II) and Cd(II) ions, respectively. The equilibrium experimental data for two metallic species fitted well by the Langmuir model. The values of ΔG° at all temperatures are negative, indicating the spontaneous nature of the biosorption process. When the metal ions competed (in the case of the biosorption from their mixture), the amounts of biosorption onto microalgae cells entrapped in beads were 0.857 ± 0.033 mmol/g for Cu(II) and 0.593 ± 0.024 mmol/g for Cd(II). Under noncompetitive and competitive conditions, the affinity order of ions for biosorbents was Cu(II) > Cd(II).

The polluted site object of our study was located on an island nourished using different materials, including industrial by-products, inside the area of Porto Marghera (Venice Lagoon, Italy). Until the 1970s, this area was one of the most important chemical districts in Italy and was largely subjected to heavy metals and metalloids pollution. In the year 2004, some Populus and Salix spp. had been planted in this polluted site in order to investigate both the hydrological control and the phytoremediation capability of these trees. In the present work, polluted soil was analyzed at different depths for both metals content and culturable microbial communities with the aim to evaluate the establishment of previously planted poplar and willow plants. Bacteria were characterized on the basis of the r/K-strategists distribution since r-strategists (fast-growing bacteria) and K-strategists (slow-growing bacteria) are characteristic for unstable and stable environments, respectively. A better characterization of bacterial communities composition was obtained from colony development and eco-physiological indices. Results appeared to confirm a good establishment of poplar and willow plants in the heavy metal contaminated site.

Recently, there has been increasing concern about perfluorinated compounds, especially perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) due to their biotic and abiotic persistence and chronic toxicity. To characterize the spatial distribution and seasonal variation of PFOS and PFOA in the aquatic and oceanic environment of Singapore, more than 100 water samples from reservoirs, rivers/canals, coastal waters, and treated effluents of wastewater treatment plants (WWTPs) were collected and analyzed in this study. Solid-phase extraction followed by high-performance liquid chromatography (HPLC) coupled with tandem MS (HPLC/MS/MS) was applied to quantitatively identify PFOS and PFOA. PFOS concentrations in surface waters, wastewaters and coastal waters were in the range of 2.2–87.3 ng/L, 5.8–532 ng/L, and 1.9–8.9 ng/L, respectively, while those of PFOA were 5.7–91.5 ng/L, 7.9–1,060 ng/L, 2.4–17.8 ng/L, respectively. Compared with surface waters and wastewaters, coastal waters had lower concentrations of PFOS and PFOA. Highest concentration of PFOA (532 ng/L) and PFOA (1,060 ng/L) were observed in treated effluents of two WWTPs. Our results suggest that coastal waters in the western area of Singapore are more heavily contaminated than those in the middle and eastern areas. The release of effluents from WWTPs is an important pathway by which perfluorinated compounds enter the oceanic environment. Between dry season and wet season, significant seasonal differences (p = 0.025) were observed in surface waters for PFOS only, while no discernable seasonal differences were found for both PFOS and PFOA in coastal waters and wastewaters.

Pharmacologically active substances used in the treatment of human and animal illnesses may usually enter the aquatic environment via effluents from sewage treatment plants, as they are not completely biodegraded or removed during waste water treatment. 17β-Estradiol genotoxicity was evaluated in Oreochromis niloticus (family Cichlidae) using micronucleus test, other nuclear abnormalities assessment, and the comet assay with erythrocytes. Fish were exposed to aqueous systems contaminated with 6 ng/L 17β-estradiol for three periods: 24 h, 48 h, and 10 days. The results showed that 17β-estradiol has genotoxic potential in different periods, since significant differences (P = 0.036) were observed in the micronucleus frequencies of the 10-day exposure groups in relation to the control group. Also, the same was observed when comparing the nuclear abnormality frequencies (P = 0.018) of the 24-h exposure group with the negative control group, and when using comet assay (P < 0.001) for 48-h evaluations. The tested concentration of the 17β-estradiol gave rise to mutagenic and genotoxic effects on the blood cells of O. niloticus, therefore the substance being considered a clastogenic chemical contaminant on both acute and chronic exposures. The assessment using a combination of micronucleus test, nuclear abnormalities, and comet assays proved to be suitable and useful in the genotoxicity testing of 17β-estradiol at nanograms per liter.

A 9-month-long continuous flow column study was carried out to investigate Cr(VI) removal by Fe0 with the presence of humic acid. The study focused on the influences of humic acid promoted dissolved iron release and humic acid aggregation in Fe0 columns receiving synthetic Cr(VI) contaminated groundwater containing various components such as bicarbonate and Ca. The effects of humic acid varied significantly depending on the presence of Ca. In Ca-free columns, the presence of humic acid promoted the release of dissolved iron in the forms of soluble Fe-humic acid complexes and stabilized fine Fe (hydr)oxide colloids. As a result, the precipitation of iron corrosion products was suppressed and the accumulation of secondary minerals on Fe0 surfaces was diminished, and a slight increase in Cr(VI) removal capacity by 18% was record compared with that of humic acid-free column. In contrast, in the presence of Ca, as evidenced by the SEM and FTIR results, humic acid greatly co-aggregated with Fe (hydr)oxides and deposited on Fe0 surfaces. This largely inhibited electron transfer from Fe0 surfaces to Cr(VI) and reduced the drainable porosity of the Fe0 matrix, resulting in a significant decrease in Cr(VI) removal capacity of Fe0. The Cr(VI) removal capacity was decreased by 24.4% and 42.7% in humic acid and Ca receiving columns, with and without bicarbonate respectively, compared with that of Ca and humic acid-free column. This study yields new considerations for the performance prediction and design of Fe0 PRBs in the environments rich in natural organic matter (NOM).

Different substrates were evaluated to investigate their effect on nitrate removal and denitrifying bacterial community in soils obtained from wetland. Serial batch kinetic tests were conducted on soils obtained from wetland mixed with glucose and sawdust using KNO3 solution. Column tests were also conducted on soils obtained from wetland mixed with three different substrates (glucose, sawdust, and scoria coated with zero-valent iron) using KNO3 solution. For the batch tests, the nitrate removal efficiency for soil mixed with glucose was comparable to that for soil mixed with sawdust, but the nitrate removal rate for soil mixed with glucose (23.3 NO3 −-N mg/L-d) was approximately eight times higher than that for soil mixed with sawdust (2.8 NO3 −-N mg/L-d). For column tests among soil samples, nitrate removal efficiency was highest in soil mixed with glucose, which is an easily biodegradable carbon source. Removal efficiency increased with increasing incubation time for both soil samples with glucose and sawdust. A phylogenetic analysis based on nitrate reductase gene demonstrated that the different carbon sources affected both the diversity and compositions of the denitrifying bacterial in soil samples.