In two saltmarshes, Old Hall in the Blackwater (southeast England) and Warton Bank in the Ribble (northwest England), we took vegetation and soil samples every six to eight weeks from August/September 2024 to January 2025 to characterise seasonal denitrification and vegetation dynamics. The data includes, vegetation species and diversity; seawater and porewater samples (NO3-, NH4+, PO43-); seawater ion concentrations (Cl-, Na2+, K+, Br-, Mg3+ and Ca2+); moisture and organic matter content in the sediment. A key ecosystem service in coastal systems is the remediation of nutrient pollution through sediment burial, vegetative uptake and microbial processing. Denitrification is a facultative anaerobic process where microbial activity transforms nitrate (NO3-), which in high concentrations can be environmentally harmful, into the environmentally benign dinitrogen gas (N2). Denitrification's magnitude is considered particularly important in saltmarsh systems compared to other habitats, although an intermediate product, nitrous oxide (N2O), can also be given off and contribute to climate change. Full details about this dataset can be found at https://doi.org/10.5285/72962722-bd56-4b3e-b397-90ceec6c821e

This dataset contains results from in situ field measurements of riverbed nitrogen transformations in the Hammer Stream, a sandy tributary of the River Rother in West Sussex, UK. Measurements were performed in November 2014 and February, April and July 2015. The data include baseline concentrations of nutrients (NO2, NO3, NH3, PO4), chloride, oxygen, pH, temperature, Fe(II), organic carbon, 15N-N2 and methane (CH4) and nitrous oxide (N2O) sampled from porewater prior to injection of 15N-nitrate. Full details about this dataset can be found at https://doi.org/10.5285/7ded510f-3955-4b92-851d-29c0f79a0b99

We surveyed two seagrass beds and two mudflats in each of six coastal sites in England (Holy Island, Blackwater, Thames, Chichester, Plymouth, Morecambe) between December 2024 and March 2025 to characterise national differences in denitrification rates and their relationship with potential drivers. A key ecosystem service in coastal systems is the remediation of nutrient pollution through sediment burial, vegetative uptake and microbial processing. Denitrification is a facultative anaerobic process where microbial activity transforms nitrate (NO3-), which in high concentrations can be environmentally harmful, into the environmentally benign dinitrogen gas (N2). Denitrification's magnitude is considered particularly important in saltmarsh systems compared to other habitats, although an intermediate product, nitrous oxide (N2O), can also be given off and contribute to climate change. This data accompanies the technical report "Denitrification dynamics and relationships with potential drivers across English saltmarshes, seagrass beds, and mudflats: Capturing national variation in space and time" Full details about this dataset can be found at https://doi.org/10.5285/ea9811f4-5856-4a7e-bbe6-dcea9c115ea2

We surveyed two salt marshes in each of six estuaries (Solway, Morecambe Bay, Ribble, Humber, Blackwater, Chichester) between September and November 2024 to characterise national differences in denitrification rates and their relationship with potential drivers. A key ecosystem service in coastal systems is the remediation of nutrient pollution through sediment burial, vegetative uptake and microbial processing. Denitrification is a facultative anaerobic process where microbial activity transforms nitrate (NO3-), which in high concentrations can be environmentally harmful, into the environmentally benign dinitrogen gas (N2). Denitrification's magnitude is considered particularly important in saltmarsh systems compared to other habitats, although an intermediate product, nitrous oxide (N2O), can also be given off and contribute to climate change. Full details about this dataset can be found at https://doi.org/10.5285/26efc506-a265-4bb1-8296-d6988ab8d714

This dataset contains water chemistry and phytoplankton cell counts collected from 3 different depths at 3 different sites in Durleigh Reservoir in Somerset, England, during 2018. Water samples were collected on 22 Feb, 5 Apr, 20 Apr, 30 May, 13 Jun, 27 Jun, 9 Jul, 24 Jul, 20 Aug, 21 Aug, 22 Aug, 23 Aug, 24 Aug, and 5 Oct 2018. The data available to download includes phytoplankton cell counts (cells/ml), turbidity (NTU), pH, Ammonia (mg/l), total oxidised nitrogen (mg/l) nitrite (mg/l), nitrate (mg/l), ammonium (mg/l), orthophosphate (mg/l), silica (mg/l), Potassium (mg/l), Calcium (mg/l), Geosmin (ng/l), 2-MIB (ng/l), total and soluble manganese, iron, copper, magnesium, zinc, and aluminium (all: mg/l). Full details about this dataset can be found at https://doi.org/10.5285/f5f85f15-8f3a-474c-ae58-7cdeab2a53ca

Data on the carbon and nitrogen cycling in soils from different geologies within the Hampshire Avon catchment, UK. The dataset also includes functional gene data, anion and cation concentrations, methane production and oxidation potential, and nitrification, denitrification and mineralization rates. Data were collected between February 2013 and November 2014. Data were collected to address the hypotheses of how the functional microbial community involved in carbon and nitrogen cycling changed seasonally and with geology. Data were collected as part of the project "The role of lateral exchange in modulating the seaward flux of C, N, P", funded under NERC's Macronutrients Cycles research programme. Full details about this dataset can be found at https://doi.org/10.5285/83f83414-f644-4684-ad5b-e1237fb12fc5

Discrete data for major ions and nutrients in river water for 13 sites in the Humber catchment over the periods 1993 to 1997 and 1996 to 1997 and for 3 sites from the Tweed catchment over the period 1994 to 1997. Ions and nutrients measured were: Ammonia, Calcium (dissolved), Magnesium (dissolved), Potassium (dissolved), Sodium (dissolved), Bromide-ion, Carbon (organic dissolved), Chloride-ion, Nitrate, Nitrite, Phosphorus (soluble reactive), Phosphorus (total dissolved), Silicate (reactive dissolved), Sulphate, Carbon (organic particulate), Nitrogen (particulate), Phosphorus (total). Sites were sampled at regular weekly intervals and more intermittently during high flows (on average an extra sampling once a month per site). Samples were obtained using a wide neck PTFE bottle in a plastic covered bottle carrier (lowered from bridges where possible otherwise collected by immersing sample bottle by hand in the water as near the main flow as possible). Samples were filtered through Whatman 0.45um sterile membrane filters immediately on return to laboratory. Samples stored in sterilin tubes in the dark at 40C and analysed by Dionex DX100 ion chromatography system. Silicate reactive dissolved and Chloride-ion concentrations were determined by automated colourimetry and dissolved organic carbon concentrations were determined using a TOCsin II aqueous carbon analyser. Some samples on the River Aire were collected using EPIC automatic samplers. The analysis was carried out by members of the analytical chemistry section at York University (from April 1994 until November 1996) and at Wallingford Institute of Hydrology (September 1993 to April 1994 and December 1996 to April 1997), as part of the Land Ocean Interaction Study (LOIS). Full details about this dataset can be found at https://doi.org/10.5285/4482fa14-aee2-4c7f-9c62-a08dc9704051

[THIS DATASET HAS BEEN WITHDRAWN]. Soil solution data from the UK Environmental Change Network (ECN) terrestrial sites. Variables measured include pH, conductivity, alkalinity, aluminium, calcium, chloride, ammonium, nitrate nitrogen, phosphate phosphorous, potassium, sulphate sulphur, sodium, total nitrogen and total dissolved phosphorous. These data are collected by suction samplers at all of ECN's terrestrial sites using a standard protocol. They represent continuous fortnightly records from 1992 to 2012. ECN is the UK's long-term environmental monitoring programme. It is a multi-agency programme sponsored by a consortium of fourteen government departments and agencies. These organisations contribute to the programme through funding either site monitoring and/or network co-ordination activities. These organisations are: Agri-Food and Biosciences Institute, Biotechnology and Biological Sciences Research Council, Cyfoeth Naturiol Cymru - Natural Resources Wales, Defence Science & Technology Laboratory, Department for Environment, Food and Rural Affairs, Environment Agency, Forestry Commission, Llywodraeth Cymru - Welsh Government, Natural England, Natural Environment Research Council, Northern Ireland Environment Agency, Scottish Environment Protection Agency, Scottish Government and Scottish Natural Heritage. Full details about this dataset can be found at https://doi.org/10.5285/456c24dd-0fe8-46c0-8ba5-855c001bc05f

Soil solution data from the UK Environmental Change Network (ECN) terrestrial sites. Variables measured include pH, conductivity, alkalinity, aluminium, calcium, chloride, ammonium, nitrate nitrogen, phosphate phosphorous, potassium, sulphate sulphur, sodium, total nitrogen and total dissolved phosphorous. These data are collected by suction samplers at all of ECN's terrestrial sites using a standard protocol. They represent continuous fortnightly records from 1992 to 2015. ECN is the UK's long-term environmental monitoring programme. It is a multi-agency programme sponsored by a consortium of fourteen government departments and agencies. These organisations contribute to the programme through funding either site monitoring and/or network co-ordination activities. These organisations are: Agri-Food and Biosciences Institute, Biotechnology and Biological Sciences Research Council, Cyfoeth Naturiol Cymru - Natural Resources Wales, Defence Science & Technology Laboratory, Department for Environment, Food and Rural Affairs, Environment Agency, Forestry Commission, Llywodraeth Cymru - Welsh Government, Natural England, Natural Environment Research Council, Northern Ireland Environment Agency, Scottish Environment Protection Agency, Scottish Government and Scottish Natural Heritage. Full details about this dataset can be found at https://doi.org/10.5285/b330d395-68f2-47f1-8d59-3291dc02923b

Precipitation chemistry data from the UK Environmental Change Network (ECN) terrestrial sites. Variables measured include pH, conductivity, alkalinity, aluminium, calcium, chloride, ammonium, nitrate nitrogen, phosphate phosphorous, potassium, sulphate sulphur, sodium, total nitrogen and total dissolved phosphorous. These data are collected by a bulk collector at all of ECN's terrestrial sites using a standard protocol. They represent continuous weekly records from 1992 to 2015. ECN is the UK's long-term environmental monitoring programme. It is a multi-agency programme sponsored by a consortium of fourteen government departments and agencies. These organisations contribute to the programme through funding either site monitoring and/or network co-ordination activities. These organisations are: Agri-Food and Biosciences Institute, Biotechnology and Biological Sciences Research Council, Cyfoeth Naturiol Cymru - Natural Resources Wales, Defence Science & Technology Laboratory, Department for Environment, Food and Rural Affairs, Environment Agency, Forestry Commission, Llywodraeth Cymru - Welsh Government, Natural England, Natural Environment Research Council, Northern Ireland Environment Agency, Scottish Environment Protection Agency, Scottish Government and Scottish Natural Heritage. Full details about this dataset can be found at https://doi.org/10.5285/18b7c387-037d-4949-98bc-e8db5ef4264c