Micronized Cu (μ-Cu) is used as a wood preservative, replacing toxic chromated copper arsenate (CCA). Micronized Cu is malachite [Cu₂CO₃(OH)₂] that has been milled to micron/submicron particles, with many particle diameters less than 100 nm, mixed with biocides and then used to treat wood. In addition to concerns about the fate of the Cu from μ-Cu, there is interest in the fate of the nano-Cu (n-Cu) constituents. We examined movement of Cu from μ-Cu-treated wood after placing treated-wood stakes into model wetland ecosystems. Release of Cu into surface and subsurface water was monitored. Surface water Cu reached maximum levels 3 days after stake installation and remained elevated if the systems remained inundated. Subsurface water Cu levels were 10% of surface water levels at day 3 and increased gradually thereafter. Sequential filtering indicated that a large portion of the Cu in solution was associating with soluble organics, but there was no evidence for n-Cu in solution. After 4 months, Cu in thin-sections of treated wood and adjacent soil were characterized with micro X-ray absorption fine structure spectroscopy (μ-XAFS). Localization and speciation of Cu in the wood and adjacent soil using μ-XAFS clearly indicated that Cu concentrations decreased over time in the treated wood and increased in the adjacent soil. However, n-Cu from the treated wood was not found in the adjacent soil or plant roots. The results of this study indicate that Cu in the μ-Cu-treated wood dissolves and migrates into adjacent soil and waters primarily in ionic form (i.e., Cu²⁺) and not as nano-sized Cu particles. A reduced form of Cu (Cu₂S) was identified in deep soil proximal to the treated wood, indicating strong reducing conditions. The formation of the insoluble Cu₂S effectively removes some portion of dissolved Cu from solution, reducing movement of Cu²⁺ to the water column and diminishing exposure.

Rhizosphere acidification in leguminous plants can release P from the dissolution of phosphate compounds which can reduce Pb bioavailability to them via the formation of insoluble Pb compounds in their rhizosphere. A soil polluted from Pb-acid batteries effluent (SPBE), having total Pb = 639 mg kg⁻¹, was amended with six different rates (0, 0.5, 1, 2, 4 and 6%) of oxalic acid-activated phosphate rock (OAPR) and their effects on pH, available P and bioavailable Pb concentrations in the rhizosphere and bulk soils of mung bean plant were evaluated. Furthermore, the effects of these variant OAPR rates on Pb concentrations in plant parts, bioaccumulation factor (BAF) and translocation factor (TF) for Pb in grain and traits like productivity, the activities of antioxidant enzymes, and grain biochemistry were investigated. Results revealed that increasing rates of OAPR significantly increased pH values and available P while decreased bioavailable Pb concentrations in the rhizosphere over control. The highest dissolution of P in the rhizosphere was with 4 and 6% OAPR rates. As a result, the formation of insoluble Pb compounds affected on reduced Pb concentrations in shoots, roots, and grain in addition to lower grain BAF and TF values for Pb over control. Likewise, the highest plant productivity, improved grain biochemistry, high Ca and Mg concentrations, least oxidative stress, and enhanced soil alkaline phosphatase activity were found with 4 and 6% OAPR rates. The OAPR 4% rate is suggested for reducing grain Pb concentration, cell oxidative injury, and improving grain biochemistry in mung bean.

A full-scale, experimental landfarm was tested for the capacity to biodegrade oil-polluted soil under high-Arctic tundra conditions in northeast Greenland at the military outpost 9117 Station Mestersvig. Soil contaminated with Arctic diesel was transferred to the landfarm in August 2012 followed by yearly addition of fertilizer and plowing and irrigation to optimize microbial diesel biodegradation. Biodegradation was determined from changes in total petroleum hydrocarbons (TPH), enumeration of specific subpopulations of oil-degrading microorganisms (MPN), and changes in selected classes of alkylated isomers and isomer ratios. Sixty-four percent of the diesel was removed in the landfarm within the first year, but a recalcitrant fraction (18%) remained after five years. n-alkanes and naphthalenes were biodegraded as demonstrated by changing isomer ratios. Dibenzothiophenes and phenanthrenes showed almost constant isomer ratios indicating that their removal was mostly abiotic. Oil-degrading microorganisms were present for the major components of diesel (n-alkanes, alkylbenzenes and alkylnaphthalenes). The degraders showed very large population increases in the landfarm with a peak population of 1.2 × 10⁹ cells g⁻¹ of total diesel degraders. Some diesel compounds such as cycloalkanes, hydroxy-PAHs and sulfur-heterocycles had very few or no specific degraders, these compounds may consequently be degraded only by slow co-metabolic processes or not at all.

Micro-crustaceans are important grazers that control the algal blooms in eutrophic lakes. However, we know little about how these key species may be affected by long-term exposure to contaminants and when the transgenerational effects are reversible and irreversible. To address this, we investigated the effects of lead (Pb, 100 μg L⁻¹) exposure on morphology and reproduction of Moina dubia for nine consecutive generations (F1–F9) in three treatments: control, Pb, and pPb (M. dubia from Pb-exposed parents returned to the control condition). In F1–F2, Pb did not affect morphology, and reproduction of M. dubia. In all later generations, Pb-exposed M. dubia had a smaller body and shorter antennae than those in control. In F3–F6, pPb-exposed animals showed no differences in body size and antennae compared to the control, suggesting recoverable effects. In F7–F9, the body size and antennae of pPb-exposed animals did not differ compared to Pb-exposed ones, and both were smaller than the control animals, suggesting irreversible effects. Pb exposure reduced the brood size, number of broods and total neonates per female in F3–F9, yet the reproduction could recover in pPb treatment until F7. No recovery of the brood size and number of broods per female was observed in pPb-exposed animals in the F8–F9. Our study suggests that long-term exposure to metals, here Pb, may cause irreversible impairments in morphology and reproduction of tropical urban micro-crustaceans that may lower the top-down control on algal blooms and functioning of eutrophic urban lakes.

Mercury (Hg) is an environmental contaminant that poses a threat to aquatic systems globally. Temporal evaluations of Hg contamination have increased in recent years, with studies focusing on how anthropogenic activities impact Hg bioavailability in a variety of aquatic systems. While it is common for these studies and ecological risk assessments to evaluate Hg bioaccumulation and effects in wildlife, there is a paucity of information regarding Hg dynamics in reptiles. The goal of this study was to investigate temporal patterns in total mercury (THg) and methylmercury (MeHg) concentrations across a 36-year period, as well as evaluate relationships among and between destructive (kidney, liver, muscle) and non-destructive (blood, tail) tissue types in a common watersnake species. To accomplish this, we measured THg and MeHg concentrations in multiple tissues from brown watersnakes (Nerodia taxispilota) collected from Steel Creek on the Savannah River Site (SRS; Aiken, SC, USA) from two time periods (1983–1986 and 2019). We found significant and positive relationships between tail tips and destructive tissues. In both time periods, THg concentrations varied significantly by tissue type, and destructive tissues exhibited higher but predictable THg values relative to tail tissue. Methylmercury concentrations did not differ among tissues from the 1980s but was significantly higher in muscle compared to other tissues from snakes collected in 2019. Percent MeHg of THg in N. taxispilota tissues mirrored patterns reported in other reptiles, although the range of % MeHg in liver and kidney differed between time periods. Both THg and MeHg concentrations in N. taxispilota declined significantly from the 1980s to 2019, with average values 1.6 to 4-fold lower in contemporary samples. Overall, our data add further evidence to the utility of watersnakes to monitor Hg pollution in aquatic environments and suggest attenuation of this contaminant in watersnakes in our study system.

With increasing concerns on the ecological risks of pollutants, many efforts have been devoted to revealing the toxic effects of pollutants on algae or bacteria in their monocultures. However, how pollutants affect algae and bacteria in their cocultures is still elusive but crucial due to its more environmental relevance. The present review outlines the interactions between algae and bacteria, reveals the influential mechanisms of pollutants (including pesticides, metals, engineered nanomaterials, pharmaceutical and personal care products, and aromatic pollutants) to algae and bacteria in their coexisted systems, and puts forward prospects for further advancing toxic studies in algal-bacterial systems. Pollutants affect the physiological and ecological functions of bacteria and algae by interfering with their relationships. Cell-to-cell adhesion, substrate exchange and biodegradation of organic pollutants, enhancement of signal transduction, and horizontal transfer of tolerance genes are important defense strategies in algal-bacterial systems to cope with pollution stress. Developing suitable algal-bacterial models, identifying cross-kingdom signaling molecules, and deciphering the horizontal transfer of pollutant resistant genes between algae and bacteria under pollution stress are the way forward to fully exploit the risks of pollutants in natural aquatic environments.

This study demonstrated that nitrogen-doped carbon materials (NCMs) could effectively catalyze the chlorine elimination process in hexachloroethane (HCA) declorination in sulfide-containing environments for the first time. The kₒbₛ values of HCA dechlorination by sulfide in the presence of 10 mg/L NCMs were higher than that of no mediator at pH 7.3 by one or two orders of magnitude. The catalytic capabilities of NCMs on HCA dechlorination were evident in common ranges of natural pH (5.3–8.9) and it could be accelerated by the increase of pH but be suppressed by the presence of dissolved humic acid. Moreover, NCMs exhibited much better catalytic capability on HCA dechlorination compared to the carbon materials, mainly owing to the combined contributions of pyridine N, including enhanced nucleophilic attack to HCA molecule by generating newborn C–S–S and activation of HCA molecule by elongating C–Cl bonds. The functions of pyridine N in micron-sized NCMs with mesopores were better than in nano-sized NCMs on HCA dechlorination. These findings displayed the potential of NCMs, when released into sulfide-containing environments, may significantly increase the dechlorination of chlorinated aliphatic hydrocarbons.

New agronomic and management approaches are urgently required to meet the challenges of improving resource use efficiency and crop yields in intensive agricultural systems. Here we report the fertilizer N use efficiency (FNUE), fate of fertilizer N and N budgets in newly designed cropping systems as compared with conventional winter wheat-summer maize double cropping (Con. W/M) in the North China Plain. A¹⁵N labelling approach was used to quantify FNUE by these new cropping systems which included optimized winter wheat-summer maize (Opt. W/M) with two harvests in one year; winter wheat/summer maize-spring maize (W/M-M) and winter wheat/summer soybean-spring maize (W/S-M) with three harvests in two years, and spring maize (M) with one harvest in one year. The results showed that only 18–20% of fertilizer N was recovered by crops in Con. W/M. Although Opt. W/M significantly increased FNUE to 33%–35% with increased crop yields, it consumed as much groundwater as Con. W/M. The W/M-M, W/S-M and M significantly increased FNUE to 27%–44% and reduced groundwater use and fertilizer N losses when compared to Con. W/M. The W/M-M achieved a comparable grain yield, but W/S-M and M had significantly lower grain yields when compared to Con. W/M. However, grain N harvest in W/S-M was comparable with Con. W/M due to higher grain N content in soybean. Post-anthesis fertilizer N uptake provided little contribution to total N uptake, and accounted for 5%, 12%, 7% and 2% of the average N uptake for winter wheat, spring maize, summer maize and summer soybean, respectively. When taking the second crop into account, Con. W/M recovered 27% of fertilizer N, while it increased to 36%–50% under the new cropping systems. We conclude that W/M-M and W/S-M will deliver significant improvements in the environmental footprints and sustainability of intensively managed cropping systems in the North China Plain.

The distinct spatial variability in microplastic concentrations between marine regions and habitats calls for a better understanding about the transport pathways of this omnipresent pollutant in the marine environment. This study provides empirical evidence that a sessile filter feeder, the Blue mussel M. edulis, accelerates microplastic deposition by aggregating them into sinking particulate faeces and pseudofaeces. After settling to the seafloor, the bioturbation of benthic fauna quickly buries these microplastics. Collectively, these results suggest that if such biologically-mediated benthic-pelagic coupling would be integrated into hydrodynamic transport models, the spatial variability and source-sink dynamics of microplastics would be better understood. It is proposed that microplastic pollution is monitored through sampling that takes into account faeces and pseudofaeces underneath filter feeders. The implications of this detrital pathway for microplastic transfer to the seafloor, and the role of shellfish mariculture in this process, are discussed. Studies that consider filter feeders and benthic communities from other regions, and during different seasons, are needed to validate the proposed biological pump mechanism across space and time.