Sediment cores were collected from the central and northern parts of Lake Dianchi, a large and shallow eutrophic lake situated in southwest China. Total organic carbon, total nitrogen (TN), and total phosphorus (TP) as well as the δ¹³C and δ¹⁵N were analyzed in the sediment cores. Age model of the sediment cores were established according to ¹³⁷Cs geochronology, which reveals that the sedimentary record covers a period of the last 50 years. During that time, Dianchi had been undergoing a distinct conversion from oligotrophic to eutrophic, as a result of increasing nutrient loadings. The two cores displayed similar increases for values of TN and δ¹⁵N, and the variations of the both parameters matched well with that of TP, which presumably suggested that δ¹⁵N is a reliable proxy for anthropogenic nutrient input. Also, dynamics of δ¹⁵N and TP showed that anthropogenic nutrients input seemed to start in the 1970s. The upward elevation of δ¹⁵N might be ascribed to the increasing input of isotopically heavier dissolved inorganic nitrogen and the accelerated denitrification process when the lake water was oxygen-depleted. The less variation of δ¹⁵N in the uppermost several centimeters of both cores were probably the result of pollution controls carried out by the local government in the recent decade. The upward increasing of δ¹³C in the two cores seemed to be induced by the enhanced productivity since 1980, which was in accordance with limnological observation. Therefore, δ¹³C values were believed to be an effective proxy for reconstructing the history of eutrophication in Lake Dianchi. In addition, this study also suggested that carbon and nitrogen isotopes are applicable to large, shallow lakes in interpreting the past environmental change.

Soils in areas of mining and smelting of Pb-Zn ores in Southern Poland are strongly enriched in heavy metals (Zn, Pb, Fe, Cd, Tl, As). The highest concentrations of Zn (<55,506 mg kg⁻¹), Pb (<8,262 mg kg⁻¹), Cd (<220 mg kg⁻¹) and Tl (<67 mg kg⁻¹) are linked to the fine fractions of upper soil layers in sites contaminated by past exploitation and processing of ores. The high stress of metals, and the negative influence of acid waste drainage has limited the development of flora and fauna in these areas. The increasing ability of plants to grow is due to the positive symbiotic action of fungi and bacteria. The mycorrhizal communities were identified in rhizospheres rich in unstable Zn-Pb-Fe sulphides such as sphalerite, galena, pyrite and marcasite and carbonates of Zn (smithsonite) and Pb (cerussite). They occur in associations with sulphates, e.g., gypsum. In parts of fungi, secondary mineral phases containing Zn, Pb, Fe and Mn occur. Metal-bearing aggregates formed during symbiotic action between myccorhiza and bacteria connected with them. They enhance the binding of bio-available ions of Zn, Pb and Mn in the most unstable phases. Metal contents in the mycorrhizal parts of the rhizospheric soils were determined by Atomic Absorption Spectroscopy. Mineralogical investigations involved X-ray diffraction, scanning electron microscopy with energy dispersive spectrometry.

In this research, we have investigated the removal efficiency of natural organic matter (NOM) from river and stream water using potassium ferrate(VI). For the study, ferrate was added in 100-ml water sample mixed either with humic acid or with fulvic acid. The removal efficiency at the ferrate dose of 2-46 mg/l (as Fe) was 21-74% for 10 mg/l humic acid and 48-78% for 10 mg/l fulvic acid. NOM was more effectively removed either at lower pH or at higher temperature. The removal performance by ferrate was comparable to that by traditional coagulants (i.e., alum, FeSO₄·7H₂O, and FeO(OH)). In addition, the removal rate of humic acid using traditional coagulants was improved by pretreatment with a very small dose of ferrate. The reaction between ferrate and humic acid was completed within 60 s, while showing first-order kinetic, and then reached a steady state.

The use of vermicompost was expanded as natural adsorbent for cationic dyes retention. The adsorption profiles in batch and flow modes for crystal violet and methylene blue on vermicompost material were evaluated. In batch mode, a retention index higher than 97% was obtained for both compounds, while in flow condition, 40 g of dried adsorbent material were enough to remove 100 mg of crystal violet or methylene blue at column flow rates of 5 and 20 mL min⁻¹. Adsorption isotherms showed adsorptive maximum capacities for vermicompost of 0.78 and 5.47 mg g⁻¹, respectively, which were compatible with the literature. Due to this good efficiency capacity, incineration steps can be considered as acceptable disposal procedures for enriched vermicompost. From these characteristics, economical and environmental advantages of the proposed material for the evaluated cationic dyes retention were evidenced.

Municipal wastewaters with industrial discharges typically contain heavy metals which may inhibit the biological processes in wastewater treatment plants. In this study, copper inhibition on strict nitrifiers in a suspended growth (SG) reactor and a combined attached and suspended growth (A''SG) reactor was compared. Both reactors were subjected to a continuous copper input of 5 mg/L. When the accumulated total copper concentration in the reactor were approximately 25 mg/L (due to sorption to the biomass), a sharp decrease in nitrification (increase in inhibition) were observed in the SG reactor while nitrification remained the same for the A''SG reactor indicating that attached growth systems were more robust against copper toxicity than suspended growth systems. Using MINTEQA2, the concentrations of various chemical species were estimated and, of the different species present, adsorbed copper in the biomass and aqueous Cu(NH₃)₄ ⁺² were found to positively correlate with percent inhibition of nitrification. Based on the changes in the concentrations of the two species, Cu(NH₃)₄ ⁺² was probably the main chemical species responsible for inhibition of nitrification. This study has implications for wastewater treatment plants treating wastewaters with high ammonia and copper present.

The goal of this work was to study quantitatively lead bioaccumulation from a lead-doped nutrient medium by using a living aquatic macrophytes Pistia stratiotes. Several sets of aquatic plants with approximately 30 g weight were grown in greenhouse conditions and in hydroponic solutions supplied with a non-toxic Pb²⁺ concentration. The synchrotron radiation total X-ray fluorescence spectrometry was used to determine the metal concentrations in dry plants and hydroponic media as a function of time. Four different non-structural bioaccumulation models were applied to describe the process dynamics and to estimate the accumulated lead maximum capacity and rate constants. According to the experimental data, both biosorption and bioaccumulation mechanisms can be considered. Due to the low desorption rate constant, the experimental data were well described by the irreversible kinetic model. The results concerning modeling of living macrophytes' metal bioaccumulation kinetics can be used to predict the heavy metal removal dynamics from wastewaters in artificial wetlands.

Wastewater contains varieties of carbonaceous and nitrogenous compounds that undergo complicated biodegradation processes in wastewater treatment plants. How these different compounds are degraded by activated sludge in aerobic conditions is still a mystery. Researchers have been trying to interpret it using the oxygen uptake rate (OUR) derived from the respirograms of respective substrates. Several models have been proposed to interpret the substrate removal mechanisms using the experimental observations. Have we succeeded in understanding the messages by activated sludge correctly using these models? In this paper, the distinctive nature of the respirograms when activated sludge is fed with different substrates and the biokinetic models that have been developed to explain the substrate removal mechanisms using derived OUR profiles are reviewed. In addition, a sensitivity study was conducted on the recently evolved simultaneous storage and growth model to investigate the influence of key parameters on OUR profiles during the biodegradation process.

Airborne particulate matter (PM) extracts were investigated for their content of organic compounds and for the direct and oxidative DNA damage induced on lung epithelial cells A549. PM₁₀ was seasonally collected at two monitoring sites (Stations 1 and 2), characterized by different traffic loads. The cells were exposed for 30 min to extracts of PM₁₀ diluted at 0.025%, 0.05%, and 0.1% for summer samples, and at 0.05%, 0.1%, and 0.15% for winter samples. Oxidative and direct DNA damage were evaluated by formamidopyrimidine glycosylase (fpg) comet assay analyzing tail moment (TM) values from fpg-enzyme-treated cells (TMenz) and enzyme untreated cells (TM) respectively and by comet percentage analysis. Measurements relating to Station 2 showed higher levels of polycyclic aromatic hydrocarbons (PAHs), and their methyl-(methyl-PAHs) and nitro-(nitro-PAHs) derivatives in both the seasons. Nitro-PAH concentrations were higher in summer than in winter at both the stations. We found a significant increase of comet percentages at the highest dose of extract from both stations in summer and from Station 2 in winter. The TM and TMenz values relative to the summer sampling showed an early oxidative DNA damage induction also followed by direct DNA damage more evident at Station 2, that seems to correlate with the presence of higher nitro-PAH concentrations during the warm season. At both monitoring stations, the results from winter sampling campaign showed a direct DNA damage induction at 0.1% of extract and oxidative-direct DNA damage at the highest dose (0.15%).

In this biological oxygen demand (BOD) study, the manometric respirometric BOD OxiTop® method was used to monitor the biodegradation of two summer grade (SFO 1 and 2) and two winter grade light fuel oils (WFO 1 and 2) in OECD 301 F conditions, in groundwater, and in two different Finnish forest soils (mineral-poor and mineral-rich). The biodegradation measurements in the OECD 301 F conditions were carried out in two nutrient solutions for 28 days. In both solutions WFO 1 reached the highest biodegradation degree, 32% in the solution OECD 301 F, and 70% in a solution containing additional ammonium chloride. In groundwater conditions all the biodegradation degrees of fuel oils remained below 2% within the 28-day period. SFO 1 reached the highest 30 day biodegradability (4%) in mineral-poor soil, 18% in mineral-rich soil. In a 189-day measurement in a mineral-rich soil, the biodegradation degree for the SFO 1 was 94%. The manometric respirometric method proved to be a very suitable and practicable measurement method for the purpose of biodegradation studies of highly volatile light fuel oils, because in this method samples are treated to a lesser degree than in conventional methods, and dilutions are not needed. Results also indicated a considerable effect of conditions on the biodegradability in both water and soil environments. The results of these biodegradation studies could be used when planning in situ treatment methods based on natural biodegradation. In situ treatment methods are eco-efficient, and are especially suitable for sparsely populated sites.

Understanding wetland hydrogeology is important as it is coupled to internal geochemical and biotic processes that ultimately determine the fate of potential contaminant inputs. Therefore, there is a need to quantitatively understand the complex hydrogeology of wetlands. The main objective of this study was to improve understanding of saturated groundwater flow in a forested riparian wetland located on a golf course in the Lower Pee Dee River Basin in South Carolina, USA. Field observations that characterize subsurface wetland flow critical to solute transport originating from storm-generated runoff are presented. Monitoring wells were installed, and slug tests were performed to measure permeabilities of the wetland soil. A field-scale bromide tracer experiment was conducted to mimic the periodic loading of nutrients caused by storm runoff. This experiment provided spatial and temporal data on solute transport that were analyzed to determine travel times in the wetland. Furthermore, a 3-D numerical, steady-state flow model (MODFLOW) was developed to simulate subsurface flow in the wetland. A particle tracking model was subsequently used to calculate solute travel times from the wetland inlet to the outlet based on flow modeling results. It was evident that observed tracer breakthrough times were not typical of these measured wetland soil matrix conductivity values. Based on surface water sampling results at the wetland outlet, tracer arrival time was about 9 h after the injection of the tracer. These results implied an apparent mean K value of 2,050 m/day, which is 152 times larger than the mean of the measured values using slug tests (13.4 m/day). Modeling efforts clearly demonstrated this implied preferential flow behavior; particle travel times resulting from the calibrated flow model were in the order of hundreds of days, while actual travel times in the wetland were in the order of hours to a few days. This significant difference in travel times was attributed to the presence of macropores in the form of dead root channels and cavities forming a pipe-flow network. The analyses presented in this study resulted in an estimate of the ratio of matrix permeability to matrix plus macropore permeability of approximately 1/150. Eventually, the tracer test and resulting travel times between various points in the wetland were critical to understanding the true wetland flow dynamics. The final conceptual model of the hydraulic properties of the wetland soils comprised a low permeability matrix containing a web of high K macropores. Simulation of tracer transport in this system was possible using a flow model with significantly elevated K values.