The content and speciation of heavy metals can fundamentally affect the hydrolysis of sludge. This research study investigates the migration and transformation rule of heavy metals during the hydrolysis process by measuring the content of exchangeables (F1), bound to carbonates (F2), bound to Fe-Mn oxides (F3), bound to organic matter (F4), and residuals (F5) under different periods of time undergoing hydrolysis. The results show that the hydrolysis process generally stabilized Cu, Zn, Mn, Ni, Pb, Cr, and As by transforming the unstable states into structurally stable states. Such transformations and stabilization were primarily caused by the changes in local metal ion environment and bonding structure, oxidation of sulfides, pyrolyzation of organic matter, and evaporation of resulting volatile materials. An X-ray diffractometry (XRD) of the residuals conducted after hydrolysis indicated that hydrolysis did have a significant influence on the transportation and transformation of heavy metals.

A hazard assessment was conducted of contaminants found at inflow and outflow monitoring stations of the Water Conservation Areas (WCAs) in South Florida. WCAs (1, 2A, 2B 3A, 3B) lie north of Everglades National Park (ENP) and southeast of Lake Okeechobee, span almost 1400 mi², and serve a number of water resource functions which include food control for three major counties, delivering water to ENP, and water storage during dry downs and for recharging groundwater. Measured concentrations of contaminants in sediment and water were evaluated at 13 monitoring stations in the WCAs using a screening benchmark approach. Chemicals of potential ecological concern (COPECs) included herbicides, organochlorine pesticides, organochlorine industrial chemicals, and heavy metals. Of the stations, total cadmium was a COPEC at nine of them. Most sites had maximum detected concentrations of cadmium that exceeded state of Florida (USA) water quality criteria standards. Beryllium, copper, mercury, methylmercury, and zinc (measured as total metal concentration) also exceeded surface water criteria at several sites. Several organochlorine chemicals in sediment were COPECs; chlordane, polychlorinated biphenyls, and p,p′-DDT with its metabolites (p,p′-DDD and p,p′-DDE) had more than 200 sediment benchmark exceedences. Mercury in fish tissue was a COPEC at S5A when compared to a no-effect residue value for survival. Greater potential hazards were observed at northern monitoring sites than southern sites around the WCAs. The hazard assessment approach for screening water quality data described in this article can help focus higher tier risk assessment work, including laboratory, field, and data analysis studies, on contaminants with greater potential for adverse biological effects.

Escherichia coli (E. coli) contamination of groundwater (GW) and surface water (SW) occurs significantly through the subsurface from onsite wastewater treatment systems (OWTSs). However, E. coli transport in the subsurface remains inadequately characterized at the field scale, especially within the vadose zone. Therefore, the aim of this research is to investigate the impact of groundwater fluctuations (e.g., recharging, discharging conditions) and variable conditions in the vadose zone (e.g., pulses of E. coli flux) by characterizing E. coli fate and transport in a linked surface water-soil water-groundwater system (SW-SoW-GW). In particular, this study characterizes the impact of flow regimes on E. coli transport in the subsurface and evaluates the sensitivity of parameters that control the transport of E. coli in the SW-SoW-GW system. This study was conducted in Lake Granbury, which is an important water supply in north-central Texas providing water for over 250,000 people. Results showed that there was less removal of E. coli during groundwater recharge events as compared to GW discharge events. Also, groundwater and surface water systems largely control E. coli transport in the subsurface; however, temporal variability of E. coli can be explained by linking the SW-SoW-GW system. Moreover, sensitivity analysis revealed that saturated water content of the soil, total retention rate coefficient, and hydraulic conductivity are important parameters for E. coli transport in the subsurface.

We conducted a field experiment to determine whether application of biosolids (municipal sewage sludge) to degraded areas of the Brazilian Atlantic rainforest had the potential to contaminate native forest species with trace metals in the sandy soils of the region. Treatments consisted of 0, 2.5, 5, 10, 15, and 20 dry Mg biosolids ha⁻¹, with nine native pioneer, secondary, and climax tree species assessed for metal uptake: capixingui, aroeira-pimenteria, canafístula, cedro-rosa, mutamba, angico-vermelho, copaíba, jatobá, and jequitibá. Biosolid application did not have a statistically significant effect on metal concentrations in soil, and Cd was the only metal with increased availability. No increased metal uptake was seen in tree foliage sampled at 6 and 12 months after application. Additional longer-term study is recommended; however, the results of this study indicate biosolids could be used in Atlantic rainforest reclamation in degraded sandy soils with little impact on soil accumulation and tree uptake of trace metals.

In this study, the genotoxic and histopathological effects of olive-mill wastewater (OMW) on the tissue cells of Lepomis gibbosus were investigated. The fish were caught from Topçam dam lake (Çine/Aydın) and were exposed to the wastewater in 50-L aquariums which contained 0.5 % OMW for 3–5 and 7 days. In genotoxic investigations, a statistically significant increase was observed in the frequency of micronuclei in the L. gibbosus in experimental groups. As a result of the exposure to OMW, histopathological findings which showed a parallel increase with the amount of exposure in the gill, liver and muscle tissues were determined. In the gills, disruption of lamellae shape, shortening and breakage of primary and secondary lamellae, fusion and branching, separation in the secondary lamellae epithelium, ballooning dilation, hyperplasia in support cells and increase in mucus cells were observed. In the parenchyma of the liver, a difference in local staining, focal necrosis, haemorrhaging in necrotic areas, oedema of blood vessels, expansion in sinusoids, congestion and dilation in portal veins, deterioration of vessel walls, cytoplasmic vacuolization in hepatocytes, pyknotic nuclei, decrease in glycogen storage in hepatocytes near the central vein and aggregates of melanomacrophages were also observed. The necrosis in muscle bundles, widespread oedema between myofibrils, degeneration and separation in some muscle groups, decrease in glycogen content, intramuscular oedema and atrophy in the myofibers were determined in the experimental groups.

To improve the denitrification characteristics of anaerobic denitrifying bacteria and obviate the disadvantage of use of explosive hydrogen gas, tourmaline, a polar mineral, was added to the hydrogenotrophic denitrification system in this study. Microbial reduction of nitrate in the presence of tourmaline was evaluated to assess the promotion effect of tourmaline on nitrate biodegradation. The experiment results demonstrated that tourmaline speeded up the cultivation process of bacteria from 65 to 36 days. After domestication of the bacteria, nitrate (50 mg NO₃ ⁻–N L⁻¹) was completely removed within 3 days in the combined tourmaline–bacteria system, and the generated nitrite was also removed within 8 days. The reduction rate in this system is higher relative to that in the bacteria system alone. Efficient removal of nitrate by tourmaline-supported anaerobic bacteria (without external hydrogen input) indicated that tourmaline might act as the sole hydrogen donor to sustain autotrophic denitrification. Besides the production of hydrogen, the promoted activity of anaerobic denitrifying bacteria might be caused by the change of water properties, e.g., the pH of aqueous solutions was altered to about 8.0 and the oxidation–reduction potential decreased by 62 % in the tourmaline system. The distinctive effects of tourmaline on bacteria were related to its electric properties.

The concentrations and fractions of cadmium (Cd), copper (Cu), lead (Pb), and zinc (Zn) in soils collected from Hailuogou Glacier foreland in eastern Tibetan Plateau were analyzed to decipher their mobility, and their eco-risk was assessed combined with multiple environmental indices. The concentrations of Cd were more than ten times higher than its local background in the O horizon and nearly three times higher in the A horizon. The concentrations of Pb and Zn were relatively high in the O horizon, whereas that of Cu increased with soil depth. The main fractions of metals in the surface horizons were reducible and acid-soluble for Cd, oxidizable and residual for Cu, reducible and oxidizable for Pb, and reducible and residual for Zn. The metal mobility generally followed the order of Cd > Pb > Zn > Cu in the O horizon and Cd > Pb > Cu > Zn in the A horizon. Sorption and complexation by soil organic matters imparted an important effect on the mobilization and transformation of Cd, Pb, and Zn in the soils. The oxidizable Cu fraction in the soils showed significant correlation with organic matters, and soil pH mainly modulated the acid-soluble and reducible Cu fractions. The concentrations and other environmental indices including contamination factor, enrichment factor, geoaccumulation index, and risk assessment index revealed that Cd reached high contamination and very high eco-risk, Pb had medium contamination but low eco-risk, Zn showed low contamination and low eco-risk, and Cu was not contaminated in the soils. The data indicated that Cd was the priority to concern in the soils of Hailuogou Glacier catchment.

As concentrations of greenhouse gases (GHG: N₂O, CO₂, CH₄) continue to increase in the earth’s atmosphere, there is a need to further quantify the contribution of natural systems to atmospheric GHG concentrations. Within this context, characterizing GHG contributions of riparian zones following storms events is especially important. This study documents soil GHG effluxes in a North Carolina riparian zone in the days following both a natural 2.5-cm precipitation event, and that same event associated with the addition of 8.7 cm artificial rainwater in select static chambers. No significant differences in CO₂, CH₄, and N₂O fluxes in response to increased moisture were observed between a depression, a sand bar, and an upland forested area. However, in this water-limited riparian zone, less negative CH₄ fluxes (i.e., methane oxidation decreased) and higher CO₂ fluxes (i.e., aerobic respiration increased) were observed following precipitation. A short-term burst in N₂O emission was observed in the hours after precipitation occurred, but elevated N₂O emissions did not persist long enough to turn the site from the N₂O sink to a N₂O source in the 3 days following the beginning of the experiment. Our results are in contrast with riparian GHG studies in wetter environments and illustrate the importance of water limitation in regulating riparian soil response to precipitation with respect to GHG emissions. More studies should be conducted in water-limited environments (e.g., US southeast/southwest) before management strategies commonly applied in wetter environments (e.g., US Northeast/Midwest) are applied in these regions.

Pharmaceutically active compounds (PhACs) are common contaminants found in surface and groundwaters, often due to their inefficient removal from wastewater treatment plants. One way in which these compounds can be removed is via aerobic cometabolism, a process that involves oxygenases produced by microorganisms. Limited work has been done examining the efficacy of cometabolism in the removal of PhACs. Therefore, the aim of this work was to investigate the use of an alkane (pentane) in the aerobic cometabolic transformations of paracetamol, ibuprofen, naproxen, diclofenac, and nimesulide. Both paracetamol and ibuprofen (single aromatic compounds) were readily transformed, with net specific biodegradation rates equal to 1.6 and 3.2 μmol/gcₑₗₗ/day, respectively. Conversely, the two aromatic ring PhACs showed slower (naproxen and nimesulide) or no transformation (diclofenac). In addition, four of the tested PhACs (ibuprofen, paracetamol, naproxen and nimesulide) did not inhibit pentane uptake.

To demonstrate the variation and affecting factors of dissolved oxygen under different aeration strategies in polluted urban river sediment, simulation systems constructed with collected sediment and in situ overlaying water were aerated up or beneath the sediment-water interface 6 h day⁻¹ for 15 days. The results showed that aeration greatly altered the spatial pattern of DO in overlying water regardless of the way of treatment. Within the first 5 min of aeration, DO in overlying water increases rapidly from 0.86–3.13 mg L⁻¹ to the saturated range of 6.12–8.14 mg L⁻¹. During the first 5 days, aeration to water costed 5 min to reach the highest DO, while aeration to sediment costed 30 min to reach a lower highest level of DO in overlaying water. Analysis showed that DO was significantly negatively correlated with NO₂ ⁻-N and COD Mₙ , suggesting that DO was synergistically consumed by biochemical processes of organic matter degradation and nitrification. Aeration to sediment (ES group) and aeration to water (EW group) differently influenced nitrification and organic matter degradation. After daily aeration treatment, nitrification was the main oxygen-depleting process in EW group, especially after the action of the second stage of nitrification, where organic matter was probably largely degraded during aeration. However, in ES group, DO was consumed by both organic matter oxidation and nitrification processes.