There has been a growing concern with the environmental influences of nanomaterials due to recent developments in nanotechnology. This study investigates the impact and fate of hematite nanoparticles (α-Fe₂O₃ NPs) (∼14 nm in size) on a crop species, barley (Hordeum vulgare L.). For this purpose, hematite NPs (50, 100, 200, and 400 mg/L) were hydroponically applied to barley at germination and seedling stages (three weeks). Inductively coupled plasma mass spectrophotometry (ICP-MS) along with vibrating sample magnetometer (VSM) techniques were used to track the NPs in plant tissues. The effects of NPs on the root cells were observed by scanning electron microscopy (SEM) and confocal microscopy. Results revealed that α-Fe₂O₃ NPs significantly reduced the germination rate (from 80% in control to 30% in 400 mg/L), as well as chlorophyll (36–39%) and carotenoid (37%) contents. Moreover, the treatment led to a significant decline in the quantum yield of photosystem II (Fv/Fm). Leaf VSM analysis indicated a change in magnetic signal for NPs-treated samples compared with untreated ones, which is mostly attributed to the iron (Fe) ions incorporated within the leaf tissue. Besides, Fe content in the roots and leaf had gradually increased by the increasing doses of NPs, which was confirming NPs’ translocation to the aerial parts. Microscopic observations revealed that α-Fe₂O₃ NPs altered root cell morphology and led to the injury of cell membranes. This study, in the light of our findings, shows that α-Fe₂O₃ NPs (∼14 nm in size) are taken up by the roots of the barley plants, and migrate to the plant leaves. Besides, NPs are phytotoxic for barley as they inhibit germination and pigment biosynthesis. This inhibition is probably due to the injury of the cell membranes in the roots. Therefore, the use of hematite NPs in agriculture and thereby their environmental diffusion must be addressed carefully.

Contamination by polycyclic aromatic hydrocarbons (PAHs) has been observed at high elevation environments; however, the occurrence and spatial variation of PAHs in alpine lakes of China is not well understood. We measured 15 priority PAHs in the sediments of Lake Qinghai in the Qinghai-Tibet Plateau, and assessed their distribution, source, and ecological risks. The total PAH concentration ranged from 30.4 to 125.2 ng g⁻¹. Low molecular weight PAHs were dominant in the sediments, suggesting a local source for the emissions. Sediment sites closer to local settlements and rivers had higher concentration of PAHs. The concentration of PAHs was significantly correlated with pH, probably as a result of the high salinity of the lake, while it was not significantly correlated with organic matter content. Molecular diagnostic ratio analysis indicated that PAHs were derived mainly from coal and biomass combustion. Specifically, the positive matrix factorization model showed that petrogenic sources, vehicular emissions, biomass combustion, and coal combustion contributed for 11.6, 16.3, 23.6, and 48.5% of the PAHs, respectively. The risk quotient method was used to assess ecological risk of PAHs individually. The results indicate that indeno[1,2,3-cd]pyrene, benzo[b]fluoranthene, benzo[a]pyrene, phenanthrene, and anthracene would produce moderate ecological risks in 5, 20, 65, 100, and 100% of the sediment sites, respectively, while the other 10 PAH homologues would scarcely produce any serious ecological risk. We used the hierarchical Archimedean copula integral assessment model to evaluate the integral risk of PAHs. The result showed that 10, 40, and 50% of the sediment sites belong to mid-high, low, and mid-low risk levels, respectively. The current concentration and risk levels of PAHs in this study might be used as a baseline to assess the influence of future anthropogenic activities.

Arsenic (As) has been recognized as one of the most toxic metalloids present in the surface soil contaminating food chain and posing threat to human life. Sulfur (S) fertilizer is often supplied in paddy soil for rice growth, but its impact on As mobility and related bacteria remains poorly understood. In this study, a pot experiment was set up with two different types of sulfur treatments (element sulfur and Na₂SO₄) to evaluate the effect of sulfur fertilizers on As speciation in porewater, As fractions in soil, As accumulation in rice plants. Besides, rhizosphere bacterial composition and functional genes that might influence As mobility were also studied. The results revealed that the addition of 150 mg/kg Na₂SO₄ decreased As(III) and As(V) concentrations in soil porewater at maturation stage by 77% and 64%, respectively. With the same sulfur content, Na₂SO₄ was more effective than element sulfur. The addition of sulfur fertilizers promoted rice growth and reduced As accumulation in shoots, further reduced As translocation from root to above-ground parts by 39–59%. The addition of sulfur fertilizers had little effect on genes involved in As metabolism. However, the relative abundance of Fe(III) and sulfate reduction related genera increased with the addition of 150 mg/kg Na₂SO₄, consistent with the increase of Fe(III) reducing bacteria Geobacteraceae and sulfate reducing gene dsrA. The phenomenon likely influenced the decrease of As concentrations in soil porewater and rice uptake. The outcomes indicate that promoting Fe- and S- reducing bacteria in the rhizosphere by sulfur fertilizers may be one way to reduce As risk in the soil-rice system.

Condensed organic matters (COM) with black carbon-like structures are considered as long-term carbon sinks because of their high stability. It is difficult to distinguish COM from general organic matter by conventional chemical analysis, thus the contribution by and interaction mechanisms of organo-mineral complexes in COM stabilization are unclear and generally neglected. Molecular markers related to black carbon-like structures, such as benzene polycarboxylic acids (BPCAs), are promising tools for the qualitative and quantitative analysis of COM. In this study, one natural soil and two cultivated soils with 25 y- or 55 y-tillage activities were collected and the distribution characteristics of BPCAs were detected. All the investigated soils showed similar BPCA distribution pattern, and over 60% of BPCAs were detected in clay fraction. The extractable BPCA contents were substantially increased after mineral removal. The ratios of BPCA contents before and after mineral removal indicate the extent of COM-mineral particle interactions, and our results suggested that up to 73% COM were protected by mineral particles, and more stronger interactions were noted on clay than on silt. The initial cultivation dramatically decreased COM-clay interactions, and this interaction was recovered only slowly after 55-y cultivation. Kaolinite and muscovite are important for COM protection. But a possible negative correlation between BPCAs and reactive iron oxides of the cultivated soils suggested that iron may promote COM degradation when disturbed by tillage activities. This study provided a new angle to study the stabilization of COM and emphasized the importance of organo-mineral complexes for COM stabilization.

Aquatic organisms are usually exposed to various co-existing pollutants. However, toxic effects of pesticide mixtures on aquatic organisms and its potential underlying mechanism still remain unclear. The joint effects of fenpropathrin (FEN) and paclobutrazol (PAC) on zebrafish (Danio rerio) using diverse toxicological endpoints were investigated in the current work. Our data exhibited that the 96-h LC₅₀ values of FEN to zebrafish at multiple life phases ranged from 0.0029 (0.0013–0.0042) to 0.16 (0.082–0.23) mg a.i. L⁻¹, which were lower by comparison to PAC ranging from 13.16 (8.564–21.03) to 23.43 (17.94–29.91) mg a.i. L⁻¹. Combination of FEN and PAC displayed synergistic effect on embryonic zebrafish. Activities of T-SOD, Cu/Zn-SOD and CYP450 were remarkably changed in the majority of single and mixture treatments by comparison to the untreated group. The mRNA levels of 17 genes related to oxidative stress, cellular apoptosis, immune system and endocrine system were assessed, and the data suggested that embryonic zebrafish were affected by both single pesticides and their mixtures. Five genes (P53, tsh, ERα, crh and cxcl-clc) showed greater alterations when exposed to pesticide mixtures by comparison to their individual chemicals. Therefore, it is urgently necessary to conduct more studies on mixture toxicities of different pesticides to explore the chemical mixtures with synergistic interactions.

Chromium (Cr) is a toxic element among which hexavalent chromium [Cr(VI)] is more toxic than trivalent chromium [Cr(III)]. Chromium can be reduced or oxidized in soil because soil is a complex medium and various soil components affect redox reaction of Cr in soil. Therefore, Cr speciation in hydroponics and soil was compared and Cr uptake and speciation by lettuce grown in the media were evaluated. Higher phytotoxicity was found in Cr(III) spiked soil than in Cr(VI) spiked soil, while Cr toxicity was higher in Cr(VI) treated hydroponics than Cr(III) treated hydroponics. Chromium was mainly accumulated in lettuce roots as Cr(III), and more Cr was translocated from roots to shoots grown in Cr(VI) treated hydroponics than Cr(III) treated hydroponics. Accumulation of Cr in roots grown in Cr(III) treated nutrient solution reduced Fe, K, Ca, Mg, and P uptake in lettuce. Chromium valence state was Cr(III) in lettuce leaves and roots grown in both Cr(III) and Cr(VI) treated hydroponics and soil. Chromium speciation in hydroponically grown lettuce roots was Cr(III) coordinated with 6 oxygens in the first shell and 2 or 4 carbons in the second shell as analyzed by X-ray absorption spectroscopy (XAS), which was similar to chromium acetate. The valence state of Cr in Cr(III) and Cr(VI) treated nutrient solution was not changed, while Cr(VI) was reduced to Cr(III) in Cr(VI) spiked soil by soil organic matter. Spiking of Cr(III) induced reduction of Mn in soil, which resulted in an increase of bioavailable Mn concentration in the Cr(III) spiked soil. Therefore, the increased phytotoxic effect for lettuce in Cr(III) spiked soil can be attributed to the reduction of Mn and subsequent release of Mn(II). For Cr(III) contaminated soil, Mn speciation should be considered, and bioavailable Mn concentration should be monitored although Cr existed as Cr(III) in soil.

Lake eutrophication has become a serious environmental problem in China. Manipulations covering more elements of trophic pyramid are methods for lakes to obtain clear water state and should be studied in detail. In the present study, Meishan Dongpo Lake was divided into two parts, and a combined biomanipulation project was conducted in one part (RLake), and the other part was used as a control (CLake). Species of submerged-plant, fish, macrobenthos, and zooplankton were screened and a certain number of them were added to adjust the eco-chain in RLake. After restoration, the coverage of submerged macrophytes reached >85%; zooplankton greater than 0.6 mm in size increased in number, and the ratio of zooplankton biomass to chlorophyll-a (Chl-a) concentration increased. The dominant fish species changed, and disturbance of the sediment was reduced. The average density of mollusks in RLake was 111.5 ± 19.8 ind m⁻², which was much higher than that in CLake (36.7 ± 2.1 ind m⁻²). Water quality and clarity were substantially improved, and nutrient concentrations, particularly total phosphorus, total nitrogen, and Chl-a were significantly reduced. The aquatic community parameters were negatively correlated with the nutrient parameters and Chl-a. The ecological restoration have adjusted the aquatic ecosystem in RLake, and many positive feedback effects among the aquatic communities made them remove internal nutrients and Chl-a more efficiently.

An alarming rise of micro-nano plastics (MNPs) in environment is currently causing the biggest threat to biotic and abiotic components around the globe. These pollutants, apart from being formed through fragmentation of larger plastic pieces and are also manufactured for commercial usage. MNPs enter agro-ecosystem, wildlife, and human body through the food chain, ingestion or through inhalation, causing blockage in the blood-brain barrier, lower fertility, and behavioural abnormalities among other problems. Hence, it becomes essential to develop novel procedures for remediation of MNPs. Among the numerous existing methods, microbial remediation promises to degrade/recover MNPs via a green route. Since microbial remediation processes mostly depend upon biotic and abiotic factors such as (temperature, pH, oxidative stress, etc.), it becomes easy to influence changes in the plastic pollutants. Hence, with the help of recent technologies, a complete degradation/removal of MNPs can be expected by utilizing the respective carbon content as energy sources for growth of microorganisms. In this review, considering the urgent environmental need, the impact of micro-nano plastics on ecosystem along with its corresponding degradation mechanisms has been brought out. Also, importance of the various recent research approaches in MNPs remediation is highlighted. Finally, the role of enzyme and membrane technology, nanoparticle technology, and metagenomics in remediation of MNPs are discussed for the first time in detail to bring out a novel remedy for the environment.

Sludge is an inevitable by-product of municipal wastewater treatment processes, and its high moisture content poses a major challenge for its subsequent treatment and disposal. Previous studies have explored the effects of applying modified corn-core powder (MCCP) on dewatering sludge. Here, we characterized the effects of applying both MCCP and sludge-based biochar (SBB) on dewatering sludge. Analysis of the anti-shear ability of SBB revealed that SBB was a skeleton builder with high compressive strength, demonstrating that SBB could maintain the permeability of sludge under high-pressure filtration processes and facilitate the flow of bound water. Dissipative particle dynamics (DPD) was used to simulated the sludge flocculating process and verify the feasibility of the experiment. As the simulation progressed, the reaction in the sludge network reached equilibrium and the simulated structure of the sludge became loose. The dewatering performance and physicochemical properties of the treated sludge were studied to further characterize the effect of this combined technology. Compared with MCCP-sludge, MCCP&SBB-sludge, which was treated by 20% DS (mass of dry solids in sludge) of SBB and 20% DS of MCCP, achieved superior dewaterability. This combined method reduced the specific resistance of filtration by 76% and enlarged the net sludge solids yield by 138%. Further study of the properties of MCCP&SBB-sludge revealed a loose structure that resembled the structure recovered by the simulation, suggesting that the DPD simulation method simulated the sludge flocculating process successfully. Therefore, the combined application of MCCP and SBB was superior for sludge dewatering because of the synergistic effects of MCCP and SBB.

No information is available on the long-term effects on thyroid and growth hormones of children exposed to phthalate-tainted products, despite the infamous 2011 Taiwan phthalate episode. We investigated estimated daily intake levels and their long-term effects on serum thyroid and growth hormone levels in children.We recruited 166 children (2–18 years old) in three visits who provided specimens and filled out a questionnaire from the Risk Assessment of Phthalate Incident in Taiwan (RAPIT) project study from 2012 to 2016. Morning spot urine samples were analyzed for nine phthalate metabolites. Serum thyroid (triiodothyronine [T₃], thyroxine [T₄], and free T₄) and growth hormone (insulin-like growth factor-1 [IGF-1] and its binding protein 3 [IGF-BP3]) levels were measured. A generalized estimating equation model was used to evaluate associations between phthalate metabolite levels and children’s thyroid and growth hormone levels.The median metabolite levels of monomethyl phthalate (MMP), Σdibutyl phthalate (DBP), and Σdi-(2-ethylhexyl) phthalate (DEHP) at visits 1, 2, and 3 were 6.59, 10.5, and 21.0 ng/mL, 0.15, 0.24, and 0.20 nmol/mL, and 0.15, 0.17, and 0.12 nmol/mL, respectively. After adjusting for potential confounding factors, we found that levels of urinary MMP were negatively associated with T₃ (β = −0.013, p = 0.047), T₄ (β = −0.016, p = 0.006), free T₄ (β = −0.012, p = 0.002), and IGF-BP3 (β = −0.025, p = 0.003). Urinary mono-ethyl phthalate (MEP) was negatively associated with IGF-1 (β = −0.027, p = 0.029) and IGF-BP3 (β = −0.016, p = 0.018). In addition, serum free T₄ was positively associated with urinary mono-2-ethyl-5-hydroxy hexyl phthalate (MEHHP) (β = 0.016, p = 0.043), mono-2-ethyl-5-oxohexyl phthalate (MEOHP) (β = 0.015, p = 0.024), and ΣDEHPm (β = 0.019, p = 0.020).Our findings support the hypothesis that specific phthalates disturb the hemostasis of thyroid and growth hormone levels in children exposed to phthalate-tainted products.