The spatial distributions, fluxes, and environmental effects of non-methane hydrocarbons (NMHCs) were investigated in the Yellow Sea (YS) and the East China Sea (ECS) in spring. The average concentrations of ethane, propane, i-/n-butane, ethylene, propylene and isoprene in the seawater were 18.1 ± 6.4, 15.4 ± 4.7, 6.8 ± 2.9, 6.4 ± 3.2, 67.1 ± 26.7, 20.5 ± 8.7 and 17.1 ± 11.1 pmol L⁻¹, respectively. The alkenes in the surface seawater were more abundant than their saturated homologs and NMHCs concentrations (with the exception of isoprene) decreased with carbon number. The spatial variations of isoprene were consistent with the distributions of chlorophyll a (Chl-a) and Chaetoceros, Skeletonema, Nitzschia mainly contributed to the production of isoprene, while the others’ distributions might be related to their photochemical production. Observations in atmospheric NMHCs indicated alkanes in the marine atmosphere decreased from inshore to offshore due to influence of the continental emissions, while alkenes were largely derived from the oceanic source. In addition, no apparent diurnal discrepancy of atmospheric NMHCs (except for isoprene) were found between daytime and night. As the main sink of NMHCs in seawater, the average sea-to-air fluxes of ethane, propane, i-/n-butane, ethylene and propylene were 31.70, 29.75, 18.49, 15.89, 239.6, 67.94 and 52.41 nmol m⁻² d⁻¹, respectively. The average annual emissions of isoprene accounted for 0.1–1.3% of the global ocean emissions, which indicated that the coastal and shelf areas might be significant sources of isoprene. Furthermore, this study represents the first effort to estimate the environmental effects caused by NMHCs over the YS and the ECS and the results demonstrated contributions of alkanes to ozone and secondary organic aerosol (SOA) formation were lower than those of the alkenes and the largest contributor was isoprene.

Chlorinated paraffins (CPs), a type of toxic and persistent organic substances, can persist in environmental media for a long time and have adverse effects on human health. Thus, it is of great importance to investigate the accumulation and environmental behavior of CPs in industrial areas. In this study, farmland soil, water, and sediment core samples from abandoned oxidation ponds used by three chemical plants to treat wastewater over the past 38 years were investigated in detail. Results show that the concentration of CPs in sediments varied significantly with the water flow direction. The oxidation pond closest to a sewage outlet had the highest concentrations of short-chain chlorinated paraffin (SCCPs) and medium-chain chlorinated paraffin (MCCPs), within the ranges of 44.0–6.21 × 10⁴ ng/g dw (mean 9.32 × 10³ ng/g dw) and 143–1.30 × 10⁶ ng/g dw (mean 1.22 × 10⁵ ng/g dw), respectively. However, in the oxidation pond farthest from the sewage outlet, CP concentrations in sediments were significantly reduced, with ∑SCCPs and ∑MCCPs concentrations ranging from N.D.-249 ng/g dw (mean 66.8 ng/g dw) and N.D.-222 ng/g dw (mean 34.0 ng/g dw), respectively. Moreover, MCCP level in the water was below the detection limit, while the concentration of SCCP ranged from 41.0 to 1.53 × 10³ ng/L (mean 267 ng/L). Finally, a remarkable spatial trend and specific congener distribution were observed in the sediment test results. The horizontal and vertical distributions of the sediments indicate that short-chain (C₁₀₋₁₁) and low-chlorinated (Cl₆₋₇) homologs are more likely to migrate deeper or farther away from the pollution source.

Since the urbanization and industrialization are wildly spread in recent decades, the concentration of Zn in soil has increased in various regions. Although the interactions between P and Zn has long been recognized, the effect of high level of Zn on P uptake, translocation and distribution in rice and its molecular mechanism are not fully understood. In this study, we conducted both hydroponic culture and field trial with different combined applications of P and Zn to analyze the rice growth and yield, the uptake, translocation and distribution of P and Zn, as well as the P- and Zn-related gene expression levels. Our results showed that high level of Zn decreased the rice biomass and yield production, and inhibited the root-to-shoot translocation and distribution of P into new leaves by down-regulating P transporter genes OsPT2 and OsPT8 in shoot, which was controlled by OsPHR2-OsmiR399-OsPHO2 module. High Zn supply triggered P starvation signal in root, thereafter increased the activities of both root-endogenous and -secreted acid phosphatase to release more Pi, and induced the expression OsPT2 and OsPT8 to uptake more P for plant growth. On the other hand, high level of P significantly decreased the Zn concentrations in both root and shoot, and the root uptake ability of Zn through altering the expression levels of OsZIPs, which were further confirmed by the P high-accumulated mutant osnla1-2 and OsPHR2-OE transgenic plant. Taken together, we revealed the physiological and molecular mechanisms of P–Zn interactions, and proposed a working model of the cross-talk between P and Zn in rice plants. Our results also indicated that appropriate application of P fertilizer is an effective strategy to reduce rice uptake of excessive Zn when grown in Zn-contaminated soil.

Understanding the distribution and persistence of the fumigant dimethyl disulfide (DMDS) under different soil conditions would contribute to a more environmentally sustainable use of this gas. We determined the effects of soil type, soil moisture content and soil organic amendment rate on DMDS distribution and persistency using soil columns in the laboratory. The peak concentrations of DMDS at 60 cm soil depth in sandy loam soil, black soil and red loam soil were 1.9 μg cm⁻³, 0.77 μg cm⁻³, 0.22 μg cm⁻³, respectively. The total soil residues of DMDS in sandy loam soil, black soil and red loam soil were 0.4, 1.3 and 1.3%, respectively. The peak concentrations of DMDS at 60 cm soil depth and the total soil residues of DMDS applied decreased from 3.2 μg cm⁻³ to 0.9 μg cm⁻³ and 3.3 to 0.5% when soil moisture content increased from 6 to 18%, respectively. Incremental increases (0–5%) in organic amendment rates decreased DMDS distribution through the soils and increased soil residues. Wait periods were required of 7, 21 and 21 days after polyethylene (PE) film was removed to reduce residues sufficiently for cucumber seed germination in sandy loam soil, black soil and red loam soil with 12% moisture content and 0% organic amendment rate, respectively. However, no wait period was required for successful cucumber seed germination in sandy loam soils (Beijing) with 6, 12 or 18% moisture content or organic amendment rates of 1 or 5%, respectively, but in commercial practice 7 days delay would be prudent. Our results indicated that soil type, soil moisture content and organic amendment rates significantly affected DMDS distribution, persistency and residues in soil. Those factors should be taken into consideration by farmers when determining the appropriate dose of DMDS that will control soil pests and diseases in commercially-produced crops.

The spatial distribution, chemical composition and ecological risk of 16 phthalate esters (PAEs) were investigated in the sea-surface microlayer (SML), seawater and sediment samples of the Bohai Sea (BS) and the Yellow Sea (YS). The concentration levels of the ΣPAEs spanned a range of 449–13441 ng L−1 in the SML, 453–5108 ng L−1 in seawater, and 1.24–15.8 mg kg−1 in the sediment samples, respectively, with diisobutyl phthalate (DiBP), di-n-butyl phthalate (DBP) and di-ethylhexyl phthalate (DEHP) as the dominant PAEs in both the water and sediment samples. The concentrations of ΣPAEs in the BS were higher than those in the YS. The vertical distribution of ΣPAEs in the water column showed that the concentrations were higher in the surface waters, but decreased slightly with depth, and started to increase at the bottom. Additionally, PAEs were significantly enriched in the SML, with an average enrichment factor of 1.46. The ecological risk of the PAEs was evaluated by the risk quotient (RQ) method, which indicated that DEHP posed a high risk to aquatic organisms in the whole water-phase, while the RQ values of DBP and DiBP reached a high risk levels in sedimentary environment.

Polychlorinated diphenyl ethers (PCDEs) are typical halogenated aromatic pollutants that have shown various toxicological effects on organisms. However, the contamination status of PCDEs in the fresh water lakes of China remains poorly researched. In this study, the levels of 15 congeners of PCDEs in the sediments, suspended particulate matter (SPM) and water of Chaohu Lake were determined. The results showed that the ranges of concentrations of total PCDEs (ΣPCDEs) in the sediment, SPM and water were 0.279 ng g−1 dry weight (d.w.)–2.474 ng g−1 d.w., 0.331 ng g−1 d.w.–2.013 ng g−1 d.w. and 0.351 ng L−1–2.021 ng L−1, respectively. The most abundant congeners found in sediments, SPM and water were 3,3′,4,4′-tetra-CDE, deca-CDE and 2,4,6-tri-CDE, with average contributive ratios of 17.36%, 15.48% and 20.63%, respectively. The medium and higher chlorinated PCDEs (e.g., penta- and deca-CDEs) were the dominant congeners in sediments and SPM. The percentages of lower chlorinated PCDEs (e.g., tri-CDEs) in the water were higher than those in the sediments. The combined input of ΣPCDEs from the eight main tributaries to Chaohu Lake was estimated at 6.94 kg y−1. Strong linear correlations between the concentrations of ΣPCDEs and organic carbon (OC) contents in three type samples from Chaohu Lake suggested OC could influence the distribution of PCDEs in Chaohu Lake substantially. In addition, the calculated average organic carbon normalized partition coefficients (logKoc) of 15 PCDEs between water and SPM were in the range of 4.55–5.45 mL g−1. This study confirmed that Chaohu Lake is contaminated by PCDEs.

Hexavalent chromium (Cr(VI)) reduction by Geobacter sulfurreducens PCA was evaluated in batch experiments, and the form and amounts of intracellular and extra-cellular Cr(VI) reduction products were determined over time. The first-order Cr(VI) reduction rate per unit mass of cells was consistent for different initial cell concentrations, and approximately equal to (2.065 ± 0.389) x 10−9 mL CFU−1 h−1. A portion of the reduced Cr(VI) products precipitated on Geobacter cell walls as Cr(III) and was bound via carboxylate functional groups, a portion accumulated inside Geobacter cells, and another portion existed as soluble Cr(III) or organo-Cr(III) released to solution. A mass balance analysis of total chromium in aqueous media, on cell walls, and inside cells was determined as a function of time, and with different initial cell concentrations. Mass balances were between 92% and 98%, and indicated Cr(VI) reduction products accumulate more on cell walls and inside cells with time and with increasing initial cell concentration, as opposed to particulates in aqueous solution. Reduced Cr(VI) products both in solution and on cell surfaces appear to form organo-Cr(III) complexes, and our results suggest that such complexes are more stable to reoxidation than aqueous Cr(III) or Cr(OH)3. Chromium inside cells is also likely more stable to reoxidation, both because it can form organic complexes, and it is separated by the cell membrane from solution conditions. Hence, Cr(VI) reduction products in groundwater during bioremediation may become more stable against re-oxidation, and may pose a lower risk to human health, over time and with greater initial biomass densities.

Chlorinated paraffins (CPs) are industrial chemicals produced in large quantities. Short-chain CPs (SCCPs) were classified as persistent organic pollutants under the Stockholm Convention in 2017. Medium-chain CPs (MCCPs) became candidate persistent organic pollutants in 2021. CPs are now ubiquitously found in the environment. Honey bees can be exposed to CPs during foraging, and this exposure subsequently results in the contamination of honey and other bee products along with colony food production and storage. Here, SCCP and MCCP concentrations in honey collected from Chinese apiaries in 2015 and 2021 were determined. Total CP concentrations in honey from 2021 to 2015 were comparable, but the ratio of MCCPs/SCCPs was higher in 2021 than in 2015. SCCP and MCCP congener group profiles in all honey samples were similar and dominated by C₁₀–₁₁Cl₆–₇ and C₁₄Cl₆–₇, respectively. MCCP concentrations were also higher than SCCP concentrations in bees, pollen, and wax but not in bee bread, which were all collected in 2021. The order of average CP concentrations was determined as wax > bee > pollen > bee bread > honey. Poor relationships were found between SCCP concentrations in honey and other samples, but a relationship between MCCP concentrations in honey and other samples was observed. Migration tests of CPs in plastic bottles showed essentially no migration into honey during storage. The risks to humans from CPs in honey are low.

Both heavy metals and radiation could affect the proliferation and dissemination of emerging antibiotic resistance pollutants. As an environmental medium rich in radioactive metals, the profile of antibiotic resistance in uranium mine remains largely unknown. A uranium mine in Guangdong province, China was selected to investigate the distribution and influencing factors of antibiotic-resistant bacteria (ARB) and antibiotic resistance genes (ARGs) including intracellular ARGs (iARGs), adsorbed-extracellular ARGs (aeARGs), and free extracellular ARGs (feARGs). The result indicated that sulfonamide and tetracycline ARB could be generally detected in mining area with the absolute concentrations of 7.70 × 10²–5.18 × 10⁵ colony forming unit/g. The abundances of aeARGs in mine soil were significantly higher than those of iARGs (p < 0.05), highlighting the critical contribution of aeARGs to ARGs spread. The feARGs in mine drainage and its receiving river were abundant (3.38 × 10⁴–1.86 × 10⁷ copies/mL). ARB, aeARGs, and iARGs may correlate with nitrogen species and heavy metals (e.g., U and Mn), and feARGs presented a significant correlation with chemical oxygen demand (p < 0.05). These findings demonstrate the occurrence of ARB and ARGs in uranium mine for the first time, thereby contributing to the assessment and control of the ecological risk of antibiotic resistance in radioactive environments.