Ciliated protozoa are important components of the microbial food web in various habitats, especially aquatic environments. These organisms are useful bioindicators for both environmental quality assessment and the wastewater purification process. The pathogenic parasitic protozoan species Giardia and Cryptosporidium represent a significant concern for human health, being responsible for numerous disease outbreaks worldwide. The predation of cysts and oocysts in 15 ciliate species from water and sewage samples collected in Campinas, São Paulo, Brazil were verified under laboratory conditions. The ciliated protozoan species were selected based on their mode of nutrition, and only bacterivorous and suspension-feeders were considered for the experiments. The species Blepharisma sinuosum, Euplotes aediculatus, Sterkiella cavicola, Oxytricha granulifera, Vorticella infusionum, Spirostomum minus, and Stentor coeruleus ingested cysts and oocysts, the resistance forms of Giardia spp. and Cryptosporidium spp., respectively. This is the first time that the ingestion of Giardia cysts by ciliated protozoa has been reported. These findings may contribute to a better understanding of the biological removal of these pathogens from aquatic environments.

Soil contamination by heavy metals in coal mine wastelands is a significant environmental issue in most developing countries. The purpose of this study is to evaluate contamination characteristics in the coal mine wastelands of Sanlidong coal mine, Tongchuan, China. To achieve this goal, we conducted field sampling work, followed by further analysis of the properties of soil contamination and accumulation characteristics in woody plants. At this site, the pH value ranged from 4.41 to 7.88, and the nutrient content of the soil rose gradually with the time after deposition due to the weathering effect improving the soil quality. Meanwhile, the levels of Cd, Cr, Cu, Ni, and Zn gradually decreased with the passage time. Generally, heavy metal contamination was found to be more serious in the discharge refuse area, with Cd contamination at moderate or heavy levels; Ni, Zn, and Cu contamination at light levels; and with no Cr contamination. The geoaccumulation index (I gₑₒ) was highest for Cd (2.38–3.14), followed by Ni, Zn, Cu, and Cr. Heavy metals accumulated on the lower slopes and spread to the surrounding areas via hydrodynamic effects and wind. According to transfer and enrichment coefficient analyses, Robinia pseudoacacia, Ulmus pumila, and Hippophae rhamnoides with considerable biomass could be used as pollution-resistant tree species for vegetation restoration. This study provided a theoretical basis for the restoration of the ecological environment in the mining area. This report described a link between heavy metal contamination of soils and growth dynamics of woody plants in China.

Understanding plant behaviour in polluted soils is critical for the sustainable remediation of metal-polluted sites including abandoned mines. Post-operational and abandoned metal mines particularly in semi-arid and arid zones are one of the major sources of pollution by soil erosion or plant hyperaccumulation bringing ecological impacts. We have selected from the literature 157 species belonging to 50 families to present a global overview of ‘plants under action’ against heavy metal pollution. Generally, all species of plants that are drought, salt and metal tolerant are candidates of interest to deal with harsh environmental conditions, particularly at semi-arid and arid mine sites. Pioneer metallophytes namely Atriplex nummularia, Atriplex semibaccata, Salsola kali, Phragmites australis and Medicago sativa, representing the taxonomic orders Caryophyllales, Poales and Fabales are evaluated in terms of phytoremediation in this review. Phytoremediation processes, microbial and algal bioremediation, the use and implication of tissue culture and biotechnology are critically examined. Overall, an integration of available remediation plant-based technologies, referred to here as ‘integrated remediation technology,’ is proposed to be one of the possible ways ahead to effectively address problems of toxic heavy metal pollution. Graphical abstract Integrated remediation technology (IRT) in metal-contaminated semi-arid and arid conditions. The hexagonal red line represents an IRT concept based on remediation decisions by combination of plants and microbial processes.

Pseudomonas putida PYR1 and Acinetobacter baumannii INP1 isolated from Liaohe estuarine wetlands were entrapped in cinder beads to make cinder gel-beads. They were combined with reeds for bioremediation of pyrene- and indeno(1,2,3-cd)pyrene-contaminated estuarine wetlands. The results showed that the removal percentages of pyrene and indeno(1,2,3-cd)pyrene (69.2 and 89.8 % respectively) in 40 days using cinder gel-beads/reeds were obviously higher than those using cinder gel-beads(52.6 and 70.0 %) and reeds (33.5 and 78.6 %) alone, about four times those of the control (13.8 and 31.1 %). The removal efficiency of pyrene was in the order cinder gel-beads/reeds > cinder gel-beads > reeds > control, which was different from cinder gel-beads/reeds > reeds > cinder gel-beads > control of indeno(1,2,3-cd)pyrene. This result indicated that the functional mechanism to remove indeno(1,2,3-cd)pyrene with six benzene rings was different from that of pyrene. The synergistic effect of reeds and cinder gel-beads for indeno(1,2,3-cd)pyrene removal was weaker than that of pyrene. But the absorption and transformation of reeds with high efficiency were beneficial to indeno(1,2,3-cd)pyrene removal from wetlands. Additionally, microbial analysis with high-throughput sequencing presented that Gammaproteobacteria were dominant PAH-degrading groups in bioremediation with immobilized bacteria. This strategy can serve as a model system for the removal of more complex or structurally related organic compounds from contaminated sites.

The Mar Piccolo basin is an internal sea basin located along the Ionian coast (Southern Italy), and it is surrounded primarily by fractured carbonate karstic environment. Because of the karstic features, the main continental water inflow is from groundwater discharge. The Mar Piccolo basin represents a peculiar and sensitive environment and a social emergency because of sea water and sediment pollution. This pollution appears to be caused by the overlapping effects of dangerous anthropogenic activities, including heavy industries and commercial and navy dockyards. The paper aims to define the contribution of subaerial and submarine coastal springs to the hydrological dynamic equilibrium of this internal sea basin. A general approach was defined, including a hydrogeological basin border assessment to detect inflowing springs, detailed geological and hydrogeological conceptualisation, in situ submarine and subaerial spring measurements, and flow numerical modelling. Multiple sources of data were obtained to define a relevant geodatabase, and it contained information on approximately 2000 wells, located in the study area (1600 km²). The conceptualisation of the hydrogeological basin, which is 978 km² wide, was supported by a 3D geological model that interpolated 716 stratigraphic logs. The variability in hydraulic conductivity was determined using hundreds of pumping tests. Five surveys were performed to acquire hydro-geochemical data and spring flow-yield measurements; the isotope groundwater age was assessed and used for model validation. The mean annual volume exchanged by the hydrogeological basin was assessed equal to 106.93 10⁶ m³. The numerical modelling permitted an assessment of the mean monthly yield of each spring outflow (surveyed or not), travel time, and main path flow.

Major and trace element, PAH, and PCB concentrations were measured in surface sediments and particles from sediment traps collected in the First and Second Basin of the Mar Piccolo (Gulf of Taranto) in two periods (June–July and August–September, 2013). The aim of the study was to evaluate pollution degree, sediment transport and particle redistribution dynamic within the area. Results confirm the higher contamination of sediments from the First Basin observed by previous researches, particularly for Cu, Hg, Pb, total PAHs, and total PCBs. Advective transport from the First to the Second Basin appears to be the leading transfer mechanism of particles and adsorbed contaminants, as evidenced by measured fluxes and statistical analyses of contaminant concentrations in surficial sediments and particles from sediment traps. Long-range selective transports of PAHs and microbial anaerobic degradation processes for PCBs have been also observed. These results are limited to a restricted time window but are consistent with the presence of transport fluxes at the bottom of the water column. This mechanism deserves further investigation and monitoring activities, potentially being the main responsible of pollutant delivering to the less contaminated sectors of the Mar Piccolo.

In this study, the distribution of labile trace metals (LTMs; Cd, Co, Cr, Cu, Ni, Pb, and Zn) in a semi-urban runoff collector was examined to assess its influence to a natural aqueous system (Jalle River, Bordeaux, France). This river is of high importance as it is part of a natural reserve dedicated to conserving aquatic flora and fauna. Two sampling campaigns with a differing precipitation condition (period 1, spring season; and period 2, summer season associated with storms) were considered. Precipitation and water flow were monitored. The collector is active as it is receptive to precipitation changes. It influences the river through discharging water, contributing LTMs, and channeling the mass fluxes. During period 2 where precipitation rate is higher, 25 % of the total water volume of the river was supplied by the collector. LTMs were detected at the collector. Measurements were done by using diffusive gradient in thin films (DGT) probes deployed during 1, 7, and 14 days in each period. The results showed that in an instantaneous period (day 1 or D1), most of these trace metals are above the environmental quality standards (Cd, Co, Cr, and Zn). The coefficient of determination (r ² > 0.50) employed confirmed that the LTM concentrations in the downstream can be explained by the collector. While Co and Cr are from the upstream and the collector, Cd, Cu, and Zn are mostly provided by the collector. Ni, however, is mostly delivered by the upstream. Using the concentrations observed, the river can be affected by the collector in varying ways: (1) adding effect, resulting from the mix of the upstream and the collector (if upstream ˂ downstream); (2) diluted (if upstream ˃ downstream); and (3) conservative or unaffected (upstream ~ downstream). The range of LTM mass fluxes that the collector holds are as follows: (1) limited range or ˂10 g/day, Cd (0.04–1.75 g/day), Co (0.08–05.42 g/day), Ni (0.06–1.45 g/day), and Pb (0.08–9.89 g/day); (2) moderate range or 11–50 g/day, Cr (0.23–33.26 g/day) and Cu (0.77–37.88 g/day); and (3) wide range or ˃50 g/day, Zn (26.33–676.61 g/day). Hence, the collector is a major source of concern in terms of contamination. This is as the water with considerable LTMs is channeled openly to the river without any treatment.

The goal of this study was to contribute to understanding of the mechanisms behind sensitivity differences between early and late instar larvae of Chironomus riparius and to address the influence of the differences in standard testing approaches on the toxicity evaluation. A 10-day contact sediment toxicity test was carried out to assess sensitivity to cadmium exposure in relation to different age and laboratory culture line origin of test organisms. Chironomid larvae of early (OECD 218 method) and late instar (US-EPA600/R-99/064 method) differed substantially in sensitivity of traditional endpoints (OECD: LOEC 50 and 10 μg Cd/g dry weight (dw); US-EPA: LOEC > 1000 and 100 μg Cd/g dw for survival and growth, respectively). Bioaccumulated cadmium and metallothioneins (MTs) concentrations were analyzed to investigate the role of MTs in reduced sensitivity to cadmium in late instar larvae. Metallothioneins were induced after treatment to greater Cd concentrations, but their levels in relation to cadmium body burdens did not fully explain low sensitivity of late instars to cadmium, which indicates some other effective way of detoxification in late instars. This study brings new information related to the role of MTs in age-dependent toxicant sensitivity and discusses the implications of divergence in data generated by chironomid sediment toxicity tests by standardized methods using different instars.

The carbonaceous aerosol concentrations in coarse particle (PM₁₀: Dp ≤ 10 μm, particulate matter with an aerodynamic diameter less than 10 μm), fine particle (PM₂.₅: Dp ≤ 2.5 μm), and ultrafine particle (PM₀.₁₃₃: Dp ≤ 0.133 μm) carbon fractions in a rural area were investigated during haze events in northwestern China. The results indicated that PM₂.₅ contributed a large fraction in PM₁₀. OC (organic carbon) accounted for 33, 41, and 62 % of PM₁₀, PM₂.₅, and PM₀.₁₃₃, and those were 2, 2.4, and 0.4 % for EC (elemental carbon) in a rural area, respectively. OC3 was more abundant than other organic carbon fractions in three PMs, and char dominated EC in PM₁₀ and PM₂.₅ while soot dominated EC in PM₀.₁₃₃. The present study inferred that K⁺, OP, and OC3 are good biomass burning tracers for rural PM₁₀ and PM₂.₅, but not for PM₀.₁₃₃ during haze pollution. Our results suggest that biomass burning is likely to be an important contributor to rural PMs in northwestern China. It is necessary to establish biomass burning control policies for the mitigation of severe haze pollution in a rural area.

This study aims to reveal the microbial mechanism of in situ surfactant-enhanced bioremediation (SEBR). Various concentrations of rhamnolipids, Tween 80, and sodium dodecyl benzenesulfonate (SDBS) were separately sprayed onto soils contaminated with polycyclic aromatic hydrocarbons (PAHs) for years. Within 90 days, the highest level of degradation (95 %) was observed in the soil treated with rhamnolipids (10 mg/kg), followed by 92 % degradation with Tween 80 (50 mg/kg) and 90 % degradation with SDBS (50 mg/kg). The results of the microbial phospholipid fatty acids (PLFAs) suggest that bacteria dominated the enhanced PAH biodegradation (94 % of the maximum contribution). The shift of bacterial community structure during the surfactant treatment was analyzed by using the 16S rRNA gene high-throughput sequencing. In the presence of surfactants, the number of the operational taxonomic units (OTUs) associated with Bacillus, Pseudomonas, and Sphingomonas increased from 2–3 to 15–30 % at the end of the experiment (two to three times of control). Gene prediction with phylogenetic investigation of communities by reconstruction of unobserved states (PICRUSt) shows that the PAH-degrading genes, such as 1-hydroxy-2-naphthoate dioxygenase and PAH dioxygenase large subunit, significantly increased after the surfactant applications (p < 0.05). The findings of this study provide insights into the surfactant-induced shifts of microbial community, as well as critical factors for efficient bioremediation.