DOI: 10.5285/ee1b9eb7-6fbd-4dd5-8f8f-e07d32c057e4
title: Carbon and nutrient data for streams in the Peruvian Amazon

description: Data from two small streams, two rivers and rainfall fractions in the Western Amazonian basin at Tambopata National Reserve in Madre de Dios region, Peru.  Data presented are nutrients (calcium, magnesium, potassium, sodium, total soluble phosphorus and silica) and fluvial carbon - dissolved inorganic carbon (DIC) and its isotopic composition δ13C-DIC, dissolved organic carbon (DOC) and particulate organic carbon (POC).  Samples were collected during the period from February 2011 to May 2012 targeting both wet and dry seasons. 

Samples for DIC samples were collected using pre-acidified evacuated Exetainers. Established standard methods were used to take samples for DOC and nutrients. Established standard methods were used to analyse samples for DIC, DOC and nutrients These methods are outlined in the lineage. The samples were taken to understand the hydrological controls on the carbon concentrations and fluxes during different flow conditions.

The data collection was carried out as part of the Natural Environment Research Council funded Amazonica project.
description: During three field campaigns (Feb.-Apr. 2011, Sept.-Dec. 2011 and Mar.-May 2012) samples for measurement of Dissolved Inorganic Carbon (DIC), Delta 13 Carbon - Dissolved Inorganic Carbon , Dissolved Inorganic Carbon (DOC) and Particulate Organic Carbon (POC) concentrations were collected from the streams and rivers in the study area. On a selected set of samples nutrient analyses were carried out. Different flow conditions were targeted in sampling to understand the hydrological controls on the carbon concentrations and fluxes. DIC samples were collected in pre-acidified (150 micro litre of concentrated phosphoric acid) evacuated 12 millilitre (ml) exetainers (Labco Ltd). Using a 10 ml syringe (rinsed with sample water 3 times) sample was injected into the exetainers and the needle withdrawn under water to prevent air ingress. On each sampling occasion triplicate exetainers were filled. DIC samples were analysed according to the headspace method on Thermo-Fisher-Scientific Gas Bench/Delta V Plus for DIC concentration and isotopic composition Delta 13 Carbon -DIC. Initially two replicate exetainers were analysed (in randomised order) and the third sample used as a backup to check if a good agreement was not achieved between the first two. This technique is further described in Waldron et al. 2014.

DOC samples were collected in polyethylene bottles and filtered through pre-furnaced (8 hours at 450 degrees Celsius ) 0.7 micro metre glassfibre filter paper (Whatman GF/F) on the day of sampling and stored refrigerated in Nalgene bottles. Prior to the analysis aliquots of the samples were acidified to pH 3.9 and degassed to remove any DIC and analysed for DOC concentration by combustion (Thermalox TOC 2020, Analytical Sciences). The filter papers were air-dried and stored in air tight containers with indicating silica gel as a drying agent. POC concentration was measured by loss on ignition. In the laboratory the filter papers were first oven dried (3 hours at 105 degrees Celsius) to establish the dry weight which was measured on a five figure balance. Then the filter papers were furnace (16 hours at 375 degrees Celsius) and re-weighed. The weight loss was converted to mg C assuming percentage Organic Carbon is equal to 50 percent. 

Aliquots of the filtered water sample were analysed for calcium (Ca) and magnesium (Mg) by Atomic Absorption Spectrometry (Perkin Elmer Analyst 400). Potassium (K) and sodium (Na) concentrations were determined by flame photometry (Sherwood Scientific M410). Colorimetric method was used to measure total dissolved phosphorus (totP) and silicon (Si). Phosphorus analysis is based on the formation of a phosphomolybdate complex which is then reduced using ascorbic acid to give blue colour that can be measured at 880 or 700 Nano metres (nm). Silica was converted to a coloured compound using the Heteropoly Blue Molybdosilicate method (American Public Health Association, 1999) and measured at 650 nm.

Data was entered into Excel spreadsheets and exported as comma separated files for ingestion into the Environmental Information Data Centre (EIDC).