Christopher Freeman

Bangor University · School of Natural Sciences

Tropical peatlands contain one of the largest pools of terrestrial organic carbon, amounting to about 89,000 teragrams (1 Tg is a billion kilograms). Approximately 65 per cent of this carbon store is in Indonesia, where extensive anthropogenic degradation in the form of deforestation, drainage and fire are converting it into a globally significant...

Terrestrial and oceanic ecosystems contribute almost equally to the sequestration of ca 50 per cent of anthropogenic CO(2) emissions, and already play a role in minimizing our impact on Earth's climate. On land, the majority of the sequestered carbon enters soil carbon stores. Almost one-third of that soil carbon can be found in peatlands, an area...

Peatlands represent a vast store of global carbon. Observations of rapidly rising dissolved organic carbon concentrations in rivers draining peatlands have created concerns that those stores are beginning to destabilize. Three main factors have been put forward as potential causal mechanisms, but it appears that two alternatives--warming and increa...

CH4 emission in the Arctic has large uncertainty due to the lack of mechanistic understanding of the processes. CH4 oxidation in Arctic soil plays a critical role in the process, whereby removal of up to 90% of CH4 produced in soils by methanotrophs can occur before it reaches the atmosphere. Previous studies have reported on the importance of risi...

Over half of the Earth's wetlands have been reclaimed for agriculture, leading to significant soil P destabilization and leaching risks. To evaluate the effects of agricultural land use on soil P stability, we used sequential P extraction to investigate the long-term effects of wetland cultivation for rice and soybean on soil P fractions, including...

Approximately 17% of the land worldwide is considered highly vulnerable to non‐native plant invasion, which can dramatically alter nutrient cycles and influence greenhouse gas (GHG) emissions in terrestrial and wetland ecosystems. However, a systematic investigation of the impact of non‐native plant invasion on GHG dynamics at a global scale has no...

Inland waters (rivers, reservoirs, lakes, ponds, streams) and estuaries are significant emitters of methane (CH4) and nitrous oxide (N2O) to the atmosphere, while global estimates of these emissions have been hampered due to the lack of a worldwide comprehensive dataset of CH4 and N2O flux components. Here, we synthesize 2997 in‐situ flux or concen...

Changes in the effect of temperature on microbial community composition (which included microbial diversity, abundance, and structure) and enzyme activities were measured at a bog peatland in North Wales, UK in spring (April), summer (August), and autumn (November), by using a thermal gradient bar. Microbial diversity (richness) and abundance were...

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...

Reported high drug use at music festivals coupled with factors such as public urination can lead to the direct release of illicit drugs into the environment. Glastonbury Festival 2019 had 203,000 attendees, its site is intercepted by the Whitelake River providing a direct route for illicit drug pollution into the local environment. We tested for po...

Elevated atmospheric CO2 may have consequences for methane (CH4) emissions from wetlands, yet the magnitude and direction remain unpredictable, because the associated mechanisms have not been fully investigated. Here, we established an in situ macrocosm experiment to compare the effects of elevated CO2 (700 ppm) on the CH4 emissions from two wetlan...

Non-marine waters (i.e., rivers, reservoirs, lakes, ponds, streams and estuaries) are globally significant emitters of methane (CH 4 ) and nitrous oxide (N 2 O) to the atmosphere, while global estimates of these emissions have been hampered due to the lack of a worldwide comprehensive database with the collection of complete CH 4 and N 2 O flux com...

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...

Northern peatlands are substantial carbon sinks because organic matter in peat is highly stable due to the low rate of decomposition. Waterlogged anaerobic conditions induce accumulation of Sphagnum-derived phenolic compounds that inhibit peat organic matter decomposition, a mechanism referred to as the “enzymic latch”. Recent studies have predicte...

Fertilization in agricultural peatlands accelerates nutrient cycling and creates a potential risk to nearby natural peatlands. Here, using undisturbed peatlands as reference, we studied soil carbon (C), nitrogen (N), phosphorus (P) and the key enzymes for nutrient cycling at 0–50 cm soil depth in agricultural, nearby disturbed peatlands in a temper...

While iron (Fe) has been proposed to constrain dissolved organic carbon (DOC) export by forming precipitation (Fe-OC) in peatlands, uncertainties remain about the potential interactions between Fe and nitrogen. Such interactions are important for Fe and carbon exports as they can dissolve the Fe-OC through Fe reduction. Here we studied the reductio...

The addition of phenolic compounds to peatland soils has been proposed as a means of enhancing the suppression of enzymes, reducing the rate of organic matter decomposition and increasing below-ground carbon sequestration. This study evaluated the potential of phenolic enrichment as a peatland restoration strategy by adding wood chips from common t...

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 followi...

The occurrence of microplastics in marine habitats is well documented and of growing concern. The presence of these small (<5 mm) pieces of plastic is less well recorded in inland water systems. In this paper, we determine a cost-efficient and straightforward method for the collection and identification of microplastics in UK inland waters. We foun...

Salt marshes are anticipated to be exposed to elevated atmospheric CO2 and high salinity due to sea-level rise in the future. This study aims to investigate the effects of elevated atmospheric CO2 and high salinity on microbial communities using intact cores collected from a salt marsh in North Wales, UK. The cores were exposed to two levels of CO2...

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 hav...

Fisheries capture has plateaued, creating ever-greater reliance on aquaculture to feed growing populations. Aquaculture volumes now exceed those of capture fisheries globally1,2, with China dominating production through major land-use change; more than half of Chinese freshwater aquaculture systems have been converted from paddy fields1,3. However,...

Changes to climate are projected over the next 50 years for many peatland areas. As decomposition of peat-forming vegetation is likely to be intrinsically linked to these changes in climate, a clear understanding of climate-peat dynamics is required. There is concern that increased temperature and decreased precipitation could increase the rate of...

The original version of this Article contained an error in the Acknowledgements, which incorrectly omitted from the end the following: ‘In particular, we thank the staff of the Centre for Ecology and Hydrology (including A. Burden, N. Ostle and C. Evans) in relation to a NERC grant involving CF & TJ (NE/E011748/1; 2007–2010), which established the...

The globally widespread drainage of peatlands has often been shown to lead to increased concentrations and fluxes of dissolved organic carbon (DOC) in streams and rivers. Elevated DOC concentrations have implications for carbon cycling, ecosystem functioning and potable water treatment. Peatland rewetting, principally through ditch blocking, is oft...

Peatlands store 1/3 of global soil carbon, destabilisation of which contributes much to the recent increase in DOC (dissolved organic carbon) in freshwater ecosystems. One suggested mechanism for the enhanced decomposition of peat and the releases of DOC is recovery from acidification. However, no biological role in the process has yet been identif...

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,...

Peatland ecosystems contain one-third of the world's soil carbon store and many have been exposed to drought leading to a loss of carbon. Understanding biogeochemical mechanisms affecting decomposition in peatlands is essential for improving resilience of ecosystem function to predicted climate change. We investigated biogeochemical changes along a...

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 peatla...

Our growing awareness of the microbial world’s importance and diversity contrasts starkly with our limited understanding of its fundamental structure. Despite recent advances in DNA sequencing, a lack of standardized protocols and common analytical frameworks impedes comparisons among studies, hindering the development of global inferences about mi...

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 DBA...

Linear alkylbenzene sulphonate (LAS) is a major anionic surfactant used in detergents worldwide and as such is a ubiquitous constituent of domestic and municipal wastewaters. Increasingly, constructed wetlands are being employed as a low cost and sustainable alternative to traditional wastewater treatment processes. Plants are known to play a vital...

The production and decomposition of litter in mangroves plays a significant role in the nutrient and organic carbon cycles. These can be highly variable both spatially and temporally as a result of numerous factors including tidal range, forest type, abundance and type of herbivorous fauna, temperature, and microbial activity. Mangroves also play a...

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 substan...

Root exudates released by vascular plants contain significant amounts of photosynthetically-derived low molecular weight carbon compounds and gases, such as oxygen. These compounds are reported to have a priming effect on the activity of soil microbes which, in turn, release extracellular soil enzymes. Rates of root exudation are known to correlate...

Drought conditions are expected to increase in frequency and severity as the climate changes, representing a threat to carbon sequestered in peat soils. Downstream water treatment works are also at risk of regulatory compliance failures and higher treatment costs due to the increase in riverine dissolved organic carbon (DOC) often observed after dr...

Northern peatlands store 455 Pg of carbon–a third of the entire global carbon store. Carbon accumulates because phenolic inhibitors slow the rate of decomposition to below that of photosynthetic production. The disproportionate importance of phenolics in peatlands is related to the unique properties of waterlogged peat soils suppressing the activit...

Poly-β-hydroxyalkanoate (PHA) is a prokaryotic energy reserve material which has been used as an indicator of environmental stress in aquatic bacteria. The following technique has been used to quantify PHA in peatland microorganisms. Peat samples were dried, digested in sulphuric acid to convert PHA into crotonic acid, and the resulting acid determ...

Drought conditions are expected to increase in frequency and severity as the climate changes, representing a threat to carbon sequestered in peat soils. Downstream water treatment works are also at risk of regulatory compliance failures and higher treatment costs due to the increase in riverine dissolved organic carbon (DOC) often observed after dr...

Wetlands are often viewed as providing a cost-effective and natural alternative treatment strategy for ameliorating pollutants during the transit of wastewater from terrestrial to aquatic systems. Natural wetlands have been used as convenient wastewater discharge sites for at least a century while artificially constructed wetlands are becoming incr...

Peatland ecosystem services include drinking water provision, flood mitigation, habitat provision and carbon sequestration. Dissolved organic carbon (DOC) removal is a key treatment process for the supply of potable water downstream from peat-dominated catchments. A transition from peat-forming Sphagnum moss to vascular plants has been observed in...

Data interpretation and comparison in enzyme assays can be challenging because of the complex nature of the environment and variations in methods employed. This letter provides an overview of common enzyme assays, the need for methods standardization, and solutions addressing some of the concerns in microplate fluorimetric assay approaches.

Mangrove swamps accumulate a significant amount (45–98 %) of organic carbon in sediments; however, there is a knowledge gap in explaining the mechanism behind this. Through the analysis of substrate samples from a red mangrove (Rhizophora mangle) swamp in southwest Florida, USA, this study investigated whether the “enzymic latch”, which suppresses...

The Indian River Lagoon, located on the Atlantic coast of Florida (USA), is one of the most diverse estuaries in the country gathering both temperate and subtropical species. The enormous biodiversity of the Lagoon has been recently threatened by multiple, massive, phytoplankton blooms since fall 2011. As a consequence, the sea grass coverage of th...

The objective of this study was to monitor a newly constructed wetland (CW) in north Wales, UK, to assess whether it contributes to an improvement in water quality (nutrient removal) of a nearby drinking water reservoir. Inflow and outflow of the Free Water Surface (FWS) CW were monitored on a weekly basis and over a period of 6 months. Physicochem...

Coastal systems are some of the most widely invaded ecosystems on earth. Non-native and invasive species may have a negative effect on local biodiversity and can out-compete local species eradicating native fauna. The invasive mussel, Mytella charruana, was found in the Mosquito Lagoon (FL) in 2004 and has been reappearing ever since. In order to d...

The distribution and function of microorganisms are of crucial importance for the flow of matter in the Earth's biogeochemical cycles. Effects of microbial communities on the carbon and nitrogen cycles are particularly important for producing climate gases such as CO(2), CH(4), or N(2)O. However, the biogeochemical cycles are reversely impacted by...

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...

In this study we have demonstrated that plants originating from upland peat bogs are sensitive to increasing background concentrations of ozone. Peatland mesocosms from an upland peat bog in North Wales, UK were exposed to eight levels of elevated background ozone in solardomes for 4 months from May to August, with 24 h mean ozone concentrations ra...

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...

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) c...

Natural dissolved organic carbon (DOC) consists of different bio-molecular classes of compounds that are currently very difficult and time-consuming to isolate as individual compounds. However, it is possible to separate natural DOC into hydrophobic and hydrophilic fractions. Such characterisation approaches are becoming increasingly important beca...

Peatlands export significant amounts of dissolved organic carbon (DOC) to freshwaters, but the quantity of DOC reaching marine environments is typically less than the input to the fluvial system due to processing within the water column. Key removal processes include photo-chemical degradation, and heterotrophic bacterial respiration. In this study...

Peatlands and other terrestrial ecosystems export large amounts of dissolved organic carbon (DOC) to freshwater ecosystems. In catchments used for supplying drinking water, water treatment works (WTWs) can remove large quantities of this organic matter, and can therefore play a unique modifying role in DOC processing and associated greenhouse gas (...