The primary objectives of peatland restoration are to reduce greenhouse gas emissions and maintain water quality. However, the effects of human activities, such as drainage and rewetting, on pore water quality remain insufficiently understood. In this study, we synthesized pore water quality data from 197 northern peatlands, encompassing natural, drained, and rewetted systems. Our analysis revealed that drainage significantly increases the concentrations of dissolved organic carbon (DOC), ammonium, and phosphate in pore water compared to natural peatlands. While rewetting reduced these concentrations, they remained elevated relative to natural systems. Notably, pore water concentrations in rewetted peatlands were closely linked to water table levels, with peak concentrations observed under inundated conditions, particularly in fen peatlands. Over an approximately 30-year observation period, no consistent temporal trends in pore water quality following rewetting were identified. These findings highlight the complexity of pore water quality responses to rewetting and the importance of long-term monitoring for optimizing peatland restoration practices.

Microplastics (MPs) and ocean warming present a dual threat to marine phytoplankton, with significant but not fully understood effects. This study assessed how projected MP pollution and rising water temperatures influence phytoplankton biomass, abundance, and diversity. While MPs at future concentrations did not impact biomass or abundance at current temperatures, under projected warming conditions, biomass decreased by 41 % and diversity by 38.8 % in MP-exposed samples. This suggests that MP toxicity, aggregation, and reduced light penetration, intensified by warming, can inhibit phytoplankton growth. Diatoms, crucial for global primary productivity, were especially affected, with declines in their abundance and diversity potentially reducing carbon sequestration by up to 10.45 billion tons annually. Community composition shifted towards fewer genera, implying lower biodiversity and resilience, which could disrupt marine food webs and affect human populations. Seagrass wetlands, a Nature-based Solution, might mitigate some impacts by trapping MPs and limiting their effects on phytoplankton. These results highlight the urgent need for further research to address and mitigate the combined impacts of MPs and warming on marine ecosystems, due to potential broad ecological and socioeconomic repercussions.

Ground level ozone is an abiotic stress estimated to reduce mean global annual wheat yields by nearly 10%. This study in solardomes exposed an elite cultivar, and multiple lines of synthetic wheat (primary and F2) to four levels of ozone (30 ppb, 55 ppb, 80 ppb, 110 ppb) for three months, with two lines (cv Paragon and an F2 line, BC1) selected for X-ray microcomputed tomography. The uCT imaging revealed ozone’s effect on individual grain formation, both spatially within the spike and on grain shape. Reductions in grain number occurred primarily across the middle of the spike. Grain volume reductions were driven more by reduced width and depth than reduced length. Based on yield data, both lines demonstrated relative tolerance to ozone. Links between ozone’s effects on grain morphology and grain quality are also explored. These data provide information that could be utilised in wheat breeding programmes to increase tolerance to ozone of this staple food crop.

The interaction between nitrogen storage and translocation, senescence, and late phase photosynthesis is critical to the post-anthesis grain fill period in wheat, but ozone's effect on nitrogen dynamics within the wheat plant is not well understood. This study used solardomes to expose a widely grown elite spring wheat cultivar, cv. Skyfall, to four levels of ozone (30 ppb, 45 ppb, 70 ppb, 85 ppb) for 11 weeks, with two levels of nitrogen fertilization, 140 kg ha(-1) and 160 kg ha(-1), the higher rate including an additional 20 kg N ha(-1) at anthesis. Chronic ozone exposure triggered earlier senescence in the 4th, 3rd and 2nd leaves but not the flag leaf, with a similar pattern of reduced chlorophyll content in the lower, older leaf cohorts, which started before senescence became visible. At anthesis there was no evidence of any effect of ozone on nitrogen storage in upper plant parts. However, high ozone increased levels of residual nitrogen found within plant parts at harvest, with concomitant reductions in C:N ratios and Nitrogen Remobilization Efficiency. Extra nitrogen fertilization applied at anthesis appeared to ameliorate the effect of ozone on nitrogen content and nitrogen translocation. The application of N-15 ammonium nitrate at anthesis confirmed that the majority of post-anthesis nitrogen uptake had been translocated to the ear/grain by harvest, with no effect of ozone on the translocation of nitrogen around the plant. These data can inform future modelling of ozone's effect on nitrogen dynamics and global wheat yields.

Iron (Fe) oxides promote carbon store stability in conventional (aerated) soils, and yet emerging evidence shows that Fe may also contribute to C decomposition in at redox interfaces. Mineral soil addition is common during peatland cultivation, but high content of Fe in mineral soil may lead to carbon loss upon flooding of agricultural peatlands (e.g. paddies). However, the mechanisms arising in such peatlands are poorly understood. We investigated different forms of Fe, including reactive Fe associated with organic carbon (FeR-OC), in field (natural and agricultural peatlands) and in vitro incubation experiments to in order to elucidate potential pathways of Fe-mediated decomposition. Our results show that FeR and short-range-order Fe (with Fes of particular importance due to its high capacity for carbon sorption) were enriched in agricultural peatlands compared with natural peatlands, while FeR-OC level was similar in both. Although Fes accounted for 60–80% of FeR, ferrous Fe accounted for 85–90% of Fes in agricultural peatlands, suggesting that high ferrous Fe levels counteract the role of Fes in forming Fe-carbon complexes in such flooded conditions. Furthermore, controlled experiments with Fe and phenol oxidase additions demonstrated that Fe reduction could initiate a cascade effect on carbon mineralization by acting as a terminal electron acceptor, releasing dissolved organic carbon from Fe‑carbon complexes, promoting oxidative decomposition and mobilizing dissolved organic carbon in flooded agricultural peatlands. In conclusion, our study demonstrates that increased Fe levels can aggressively accelerate carbon loss in flooded agricultural peatlands through previously underestimated pathways.

Peatland reservoirs are global hotspots for drinking water provision and are likely to become more important as demand per capita rises and the climate changes. Dissolved organic carbon (DOC) is associated with harmful disinfection byproducts and reduced aesthetic quality, and its removal is the major treatment cost. Littoral zones are known to be disproportionately important for DOC production through macrophyte inputs, and such communities are predicted to expand with warming in northern regions. However, little is known about autochthonous DOC contributions and their response to climatic change. Here we exposed mesocosms to elevated CO 2 (eCO 2 ), warming and a combined treatment across a trophic gradient. Regression analysis indicated that while sediments, macrophytes, and phytoplankton are important DOC sources ( P < 0.05), benthic algal biomass showed the strongest relationship with DOC ( P < 0.05), suggesting it is an underestimated source. DOC removal indicators, namely phenol oxidase (depolymerization) and respiration (mineralization) were inversely related to DOC concentration in oligohumic ( P < 0.05) and oligotrophic ( P < 0.1) systems, suggesting heterotrophic processes are important in DOC removal. DOC concentrations increased across all systems ( P < 0.05), irrespective of trophic status, due to increased photoautotrophic inputs (macrophyte, pelagic, and benthic algae) under eCO 2 , warming, and combined scenarios, with inhibited depolymerization and mineralization under eCO 2 , even when combined with warming ( P < 0.05 and P < 0.05 excepting the oligo‐mesotrophic reservoir P < 0.1 respectively). Increased DOC loads of all fractions, regardless of provenance, are predicted in a future climate and, thus, investment in techniques to remove a greater range of DOC fractions is proposed to help “future proof” drinking water supplies.

Northern peatlands store ~30% of the world’s soil carbon. This carbon sequestration is due to slow decomposition, as illustrated by ancient wooden artefacts and ‘bog bodies’ preserved over millennia. Such artefacts suggest that carbon could be captured externally and stored long term in peat. However, whether such carbon would remain stable following lowered water tables is not known. Here, we show that adding woody litter results in preservation of the exogenous carbon, as well as protection of soil carbon within the host ecosystem from severe drought, as a result of leached polyphenolics. These compounds not only inhibit microbial extracellular and intracellular metabolism but also deprive microbial growth of iron and substrates such as carbon and nitrogen. Our results suggest that this technique harnesses natural ecosystem resilience mechanisms and may have implications for new carbon-farming approaches. Northern peatlands are a significant carbon sink but are vulnerable to decomposition during drought and low water tables. Woody litter added to these ecosystems during high water table conditions leaches polyphenolics that protect carbon stores against decomposition, even during subsequent drought.

Modern wheat cultivars are increasingly sensitive to ground level ozone, with 7–10% mean yield reductions in the northern hemisphere. In this study, three of the genome donors of bread wheat, Triticum urartu (AA), T. dicoccoides (AABB), and Aegilops tauschii (DD) along with a modern wheat cultivar (T. aestivum ‘Skyfall’), a 1970s cultivar (T. aestivum ‘Maris Dove’), and a line of primary Synthetic Hexaploid Wheat were grown in 6 L pots of sandy loam soil in solardomes (Bangor, North Wales) and exposed to low (30 ppb), medium (55 ppb), and high (110 ppb) levels of ozone over 3 months. Measurements were made at harvest of shoot biomass and grain yield. Ae. tauschii appeared ozone tolerant with no significant effects of ozone on shoot biomass, seed head biomass, or 1000 grain + husk weight even under high ozone levels. In comparison, T. urartu had a significant reduction in 1000 grain + husk weight, especially under high ozone (−26%). The older cultivar, ‘Maris Dove’, had a significant reduction in seed head biomass (−9%) and 1000 grain weight (−11%) but was less sensitive than the more recent cultivar ‘Skyfall’, which had a highly significant reduction in its seed head biomass (−21%) and 1000 grain weight (−27%) under high ozone. Notably, the line of primary Synthetic Hexaploid Wheat was ozone tolerant, with no effect on total seed head biomass (−1%) and only a 5% reduction in 1000 grain weight under high ozone levels. The potential use of synthetic wheat in breeding ozone tolerant wheat is discussed.

Nitrogen deposition and tropospheric ozone are important drivers of vegetation damage, but their interactive effects are poorly understood. This study assessed whether long-term nitrogen deposition altered sensitivity to ozone in a semi-natural vegetation community. Mesocosms were collected from sand dune grassland in the UK along a nitrogen gradient (5-25 kg N/ha/y, including two plots from a long-term experiment), and fumigated for 2.5 months to simulate medium and high ozone exposure. Ozone damage to leaves was quantified for 20 ozone-sensitive species. Soil solution dissolved organic carbon (DOC) and soil extracellular enzymes were measured to investigate secondary effects on soil processes. Mesocosms from sites receiving the highest N deposition showed the least ozone-related leaf damage, while those from the least N-polluted sites were the most damaged by ozone. This was due to differences in community-level sensitivity, rather than species-level impacts. The N-polluted sites contained fewer ozone-sensitive forbs and sedges, and a higher proportion of comparatively ozone-resistant grasses. This difference in the vegetation composition of mesocosms in relation to N deposition conveyed differential resilience to ozone. Mesocosms in the highest ozone treatment showed elevated soil solution DOC with increasing site N deposition. This suggests that, despite showing relatively little leaf damage, the 'ozone resilient' vegetation community may still sustain physiological damage through reduced capacity to assimilate photosynthate, with its subsequent loss as DOC through the roots into the soil. We conclude that for dune grassland habitats, the regions of highest risk to ozone exposure are those that have received the lowest level of long-term nitrogen deposition. This highlights the importance of considering community- and ecosystem-scale impacts of pollutants in addition to impacts on individual species. It also underscores the need for protection of 'clean' habitats from air pollution and other environmental stressors. (C) 2019 Elsevier Ltd. All rights reserved.

There have been widespread attempts to rewet peatlands in Europe and elsewhere in the world to restore their unique biodiversity as well as their important function as nutrient and carbon sinks. However, changes in hydrological regime and therefore oxygen availability likely alter the abundance of enzyme-inhibiting polyphenolic compounds, which have been suggested as a "latch" preventing large amounts of carbon from being released into the atmosphere by microbial mineralization. In recent years, a variety of factors have been identified that appear to weaken that latch including not only oxygen, but also pH. In minerotrophic fens, it is unknown if long-term peat mineralization during decades of drainage and intense agricultural use causes an enrichment or a decline of enzyme-inhibiting polyphenols. To address this, we collected peat samples and fresh roots of dominating plants (i.e., the peat parent material) from the upper 20 cm peat layer in 5 rewetted and 6 natural fens and quantified total phenolic content as well as hydrolysable and condensed tannins. Polyphenols from less decomposed peat and living roots served partly as an internal standard for polyphenol analysis and to run enzyme inhibition tests. As hypothesized, we found the polyphenol content in highly decomposed peat to be 8 times lower than in less decomposed peat, while condensed tannin content was 50 times lower in highly degraded peat. In addition, plant tissue polyphenol contents differed strongly between peat-forming plant species, with the highest amount found in roots of Carex appropinquata at 450 mg g-1 dry mass, and lowest in Sphagnum spp. at 39 mg g-1 dry mass: a 10-fold difference. Despite large and clear differences in peat and porewater chemistry between natural and rewetted sites, enzyme activities determined with Fluorescein diacetate (FDA) hydrolysis and peat degradation were not significantly correlated, indicating no simple linear relationship between polyphenol content and microbial activity. Still, samples with low contents of polyphenols and condensed tannins showed the highest microbial activities as measured with FDA.

Dune slacks are biodiverse seasonal wetlands which experience considerable fluctuations in water table depths. They are subject to multiple threats such as eutrophication and climate change, and the interactions of both of these pressures are poorly understood. In this study we measured the impact of groundwater nitrogen contamination, as ammonium nitrate (0, 0.2, 10 mg/L of DIN, dissolved inorganic nitrogen), lowered water table depth (lowered by 10 cm) and the interactions of these factors, in a mesocosm study. We measured gross nutrient budgets, evapotranspiration rates, the growth of individual species and plant tissue chemistry. This study found that nitrogen uptake within dune slack habitats is substantial. Atmospheric inputs of 23 kg N ha −1 yr. −1 were retained by the mesocosms, with no increase of nutrient levels in the groundwater, i.e. there was no leaching of excess N. When N was added to the groundwater (in addition to atmospheric N), total uptake was equivalent to 116 kg N ha −1 yr. −1 , at a groundwater DIN concentration of 10 mg/L. This resulted in increased plant tissue N concentrations showing uptake by the vegetation. The effect of lowering water tables did not influence N uptake, but did alter vegetation composition. This suggests that groundwater can be a substantial input of N to these habitats and should be considered in combination with atmospheric inputs, when assessing potential ecosystem damage.

Mowing is a common management technique employed in Europe and North America to manage seral wetland plant communities to: (a) prevent development to late succession, (b) minimise internal eutrophication and (c) conserve biodiversity. However, little is known about the effect mowing has on water quality, and the duration of any effects. Therefore, mowing treatments were applied in two abandoned fen plant communities: a Schoenus nigricans-Juncus subnodulosus (SN) community (hand-cutting) and a Cladio-Molinietum (CM) community (machine mowing). Mowing took place once in each community across three sites in North Wales, U.K. Effects on water chemistry were followed for two years post mowing.

Algal blooms resulting from the eutrophication of surface waters represent a significant ecological and water treatment issue. The potential for wetland systems to act as sinks for various types of pollutants indicates their potential for mitigating algal blooms. Although nutrient uptake in terrestrial treatment wetland systems has received substantial attention in the literature, relatively little is known about the mechanisms involved in floating constructed wetland (FCW) function for algal control and whether plant species can optimise performance. Here, the effect of FCWs on water quality including nutrient levels and algal biomass was investigated, along with the effect of planting with different species of macrophyte. All the planted FCWs showed significant potential for algal bloom mitigation in both hypereutrophic and mesotrophic systems; algal biomass control is proposed to be due to the direct uptake of nitrate and phosphate via macrophyte roots, rather than algaecidal effect of phenolic compounds. Dissolved organic carbon (DOC) release was found to differ between species, with implications for drinking water treatment.

Chlorination of drinking water protects humans from water-born pathogens, but it also produces low concentrations of dibromoacetonitrile (DBAN), a common disinfectant by-product found in many water supply systems. DBAN is not mutagenic but causes DNA breaks and elevates sister chromatid exchange in mammalian cells. The WHO issued guidelines for DBAN after it was linked with cancer of the liver and stomach in rodents. How this haloacetonitrile promotes malignant cell transformation is unknown. Using fission yeast as a model, we report here that DBAN delays G1-S transition. DBAN does not hinder ongoing DNA replication, but specifically blocks the serine 345 phosphorylation of the DNA damage checkpoint kinase Chk1 by Rad3 (ATR) at broken replication forks. DBAN is particularly damaging for cells with defects in the lagging-strand DNA polymerase delta. This sensitivity can be explained by the dependency of pol delta mutants on Chk1 activation for survival. We conclude that DBAN targets a process or protein that acts at the start of S phase and is required for Chk1 phosphorylation. Taken together, DBAN may precipitate cancer by perturbing S phase and by blocking the Chk1-dependent response to replication fork damage.

Peat represents a globally significant pool of sequestered carbon. However, peatland carbon stocks are highly threatened by anthropogenic climate change, including drought, which leads to a large release of carbon dioxide. Although the enzymatic mechanisms underlying drought-driven carbon release are well documented, the effect of drought on peatland microbial communities has been little studied. Here, we carried out a replicated and controlled drought manipulation using intact peat ‘mesocosm cores’ taken from bog and fen habitats, and used a combination of community fingerprinting and sequencing of marker genes to identify community changes associated with drought. Community composition varied with habitat and depth. Moreover, community differences between mesocosm cores were stronger than the effect of the drought treatment, emphasising the importance of replication in microbial marker gene studies. While the effect of drought on the overall composition of prokaryotic and eukaryotic communities was weak, a subset of the microbial community did change in relative abundance, especially in the fen habitat at 5 cm depth. ‘Drought-responsive’ OTUs were disproportionately drawn from the phyla Bacteroidetes and Proteobacteria. Collectively, the data provide insights into the microbial community changes occurring alongside drought-driven carbon release from peatlands, and suggest a number of novel avenues for future research.

Numerous catchment characteristics including topography, geology, soil and vegetation are reported to exert a strong influence on mean surface water properties. The present study employs a geographical information system (GIS) approach to examine, for the first time, the relationship between reservoir water quality [dissolved organic carbon (DOC) concentration, colour, nitrate concentration and pH] and catchment Phase 1 Habitat coverage. Analysis was conducted on two occasions and at two different spatial scales. Numerous statistically significant correlations were identified, suggesting the use of Phase 1 Habitat data could help improve predictive models of surface water quality. The occurrence and strength of correlations varied seasonally in response, we argue, to temporal variations in hydrological regime and anthropogenic activity. The data also suggest that the proximity of habitat types to the reservoir is significant in affecting reservoir water quality. The findings are used to recommend suitable measures for drinking water companies to mitigate against water quality issues.

Dune slacks are biodiverse seasonal wetlands which experience considerable fluctuation in water table depth. They are under threat from eutrophication and lowered water tables due to climate change and water abstraction. The biological effects caused by the interactions of these pressures are poorly understood, particularly on soil processes. We used a mesocosm experiment and laboratory assays to study the impact of lowered water tables, groundwater nitrogen contamination, and their synergistic-effects on soil microbial processes and greenhouse gas emissions. This study showed that just a 10 cm decrease in water table depth led to a reduction, in denitrification and to a corresponding increase in soil nitrogen content. Meanwhile N2O emissions occurred for longer durations within dune slack soils subject to higher concentrations of groundwater nitrogen contamination. The results from extracellular enzyme assays suggest that decomposition rates increase within drier soils shown by the increase in beta-glucosidase activity, with further sensitivity to groundwater nitrogen contamination shown by the increase in phenol oxidase activity. Dune slack soils with a 10 cm lower water table had significantly lower CH4 emissions, nearly 5 times lower in the drier soils. Our findings demonstrate that dune slacks are sensitive to both small changes in groundwater levels and to groundwater nitrogen contamination. The biological impacts from lowered water tables are likely to be intensified where there is also groundwater nitrogen contamination. (C) 2016 Elsevier Ltd. All rights reserved.

Peatlands contain more than double the amount of carbon than is found in the biomass of the world's forests. Such stores are due to the build-up of dead plant material, resulting from restraints on microbial decomposition in the peat-substrate: in particular the inhibitory effects of phenolic compounds create an 'enzymic latch' on the breakdown of organic matter. We propose that this mechanism could be harnessed for a number of peatland-based geoengineering schemes. Such strategies would involve using molecular, agronomical and biogeochemical approaches to manipulate microbial activities in peatlands maximizing their abilities to store and capture carbon. Although like all geoengineering proposals, peatland geoengineering does not offer a 'magic bullet' in reversing the effects of climate change, it potentially has numerous advantages over other suggested schemes. Most of the technologies and knowledge are already established, the projects are reversible, and they do not compete with other land uses such as food production. It can therefore be argued that peatland geoengineering offers a realistic 'Plan B' to save the planet from the effects of anthropogenic climate change.

Drained peatland catchments are reported to produce more colored, dissolved organic carbon (DOC)-rich water, presenting problems for potable water treatment. The blocking of peatland drainage ditches to restore the water table is increasingly being considered as a strategy to address this deterioration in water quality. However, the effect of ditch blocking on the potential of DOC to form trihalomethanes (THMs) has not been assessed. In this study, the effect of peat rewetting on pore water DOC concentration and characteristics (including THM formation potential [THMFP]) was assessed over 12 months using peat cores collected from two drained peatland sites. The data show little evidence of differences in DOC concentration or characteristics between the different treatments. The absence of any difference in the THMFP of pore water between treatments suggests that, in the short term at least, ditch blocking may not have an effect on the THMFP of waters draining peatland catchments.

Nutrients and faecal contaminants can enter wetland systems in a number of ways, with both biological and potentially human-health implications. In this study we used a combination of inorganic chemistry, dissolved organic matter (DOM) fluorescence and Escherichia coli and total coliform (TC) count techniques to study the sources and multiple pathways of contamination affecting a designated sand dune site of international conservation importance, surrounded by agricultural land. Analysis of stream samples, groundwater and dune slack wetlands revealed multiple input pathways. These included riverbank seepage, runoff events and percolation of nutrients from adjacent pasture into the groundwater, as well as some on-site sources. The combined techniques showed that off-site nutrient inputs into the sand dune system were primarily from fertilisers, revealed by high nitrate concentrations, and relatively low tryptophan-like fulvic-like ratios <0.4Ramanunits (R.U.). The E. coli and TC counts recorded across the site confirm a relatively minor source of bacterial and nutrient inputs from on-site grazers. Attenuation of the nutrient concentrations in streams, in groundwater and in run-off inputs occurs within the site, restoring healthier groundwater nutrient concentrations showing that contaminant filtration by the sand dunes provides a valuable ecosystem service. However, previous studies show that this input of nutrients has a clear adverse ecological impact.