PROGRAMS AND PLANS--Field collection and data processing procedures for atmospheric deposition samples In Reply Refer To: December 15, 1980 EGS-Mail Stop 412 QUALITY OF WATER BRANCH TECHNICAL MEMORANDUM NO. 81.07 Subject: PROGRAMS AND PLANS--Field collection and data processing procedures for atmospheric deposition samples The collection and analysis of atmospheric deposition samples is becoming a more prominent part of the WRD water quality program as evidenced by the Urban Hydrology Studies Program, the acid rain thrust, and an increasing number of state cooperative programs requiring such data. The present state of knowledge in data collection and interpretation techniques is, however, quite limited and the subject of much controversy, especially in the case of dry deposition (even the term dry deposition is controversial). Despite these factors, samples have been and will continue to be collected. It is imperative, therefore, that to the extent possible a set of guidelines be provided for the procedures to be followed in processing samples in the field and storing the data in the computer. An initial set of guidelines is provided in this memorandum, but modifications are likely as new information is gained. Atmospheric deposition is operationally divided into two components, wet deposition (rain, snow, fog, dew) and dry deposition (particulates, aerosols, gases). The distribution of constituent concentrations in wet deposition relative to elevation, proximity to sources of chemical constituents, and time during a wet deposition event is not very well understood at the present time. However, it is commonly held that the load of a given constituent falling on a watershed in wet deposition can be measured with acceptable precision by a limited number of samplers located throughout the watershed. The sampling precision currently is being examined in several experiments. Systematic relations between location, parameters, and composition have not yet been developed, but research on this subject is being conducted by a number of organizations. It is hoped that quantitiative guidelines on sampler location will be available within a few years. The amount of dry deposition material collected in the type of collector used by the Survey and the concentrations of constituents in this material are known to vary widely even between closely spaced samplers. These collectors are usually placed relatively close to the ground and therefore accumulate only a non-representative portion of the total dry material in the atmospheric load. The material in the collector will represent mostly those larger sized particles of local origin that move along relatively close to the ground. It is being suggested that this portion of the dry atmospheric load be called "dustfall". The collection of dustfall is probably not quantitative over the interval of collection and there is evidence to suggest that a state of equilibrium exists between material input to and output from the collector. Consequently, until further knowledge becomes available, the objective for collecting dustfall should be limited to providing a qualitative indicator of the magnitude of ambient atmospheric sources rather than attempting to quantify deposition accurately over a watershed. Correlation analysis of dustfall with runoff quality might prove beneficial but should be interpreted cautiously. Even with these constraints precipitation inputs, in general, should be considered major components of the geochemical cycle. COLLECTORS Wet deposition and dustfall samples can be collected with the Aerochem Metrics Model 30l sampling device or equivalent. Placement of the device will depend on the nature of the information required. Dustfall might be viewed in a manner similar to suspended sediment and bedload in a stream. A sampler placed low to the ground will tend to collect the larger sized particles that reflect predominantly local characteristics whereas as the sampler is placed at increasing heights the chemical constituents in the particles will reflect longer range transport phenomena. In general, an unobstructed zone should surround the sampler with no large objects protruding (or standing) above a line-of-site projected at an angle of no more than 30 degrees above the horizontal to minimize the contamination from leaves, droplets blown from tree surfaces, etc. Some protection from excessive winds is desirable and is best provided by trees sufficiently far away to not interfere with the unobstructed zone described above. The actuating mechanism for moving the coverplate over the dustfall collector should be checked frequently and adjusted to insure that the dry collector receives a minimal amount of wet deposition. On the Aerochem Metrics model this can be done preferably by decreasing or increasing the high temperature setting to increase or decrease, respectively, the sensitivity. Under certain circumstances the sensitivity can be increased by applying pressure to the grid covering the cover plate. The reduced distance between the grid and the plate permits a lesser amount of moisture to activate the mechanism. FIELD PROCEDURES The field procedures for preparing atmospheric deposition samples for laboratory analysis will have a unique set of guidelines for samples collected in the Urban Hydrology program and another set which will be the basis for all other programs. The Urban Hydrology program is a special case to insure comparability of laboratory results between stream samples and atmospheric deposition samples. Specifically, total and total recoverable analyses on urban hydrology atmospheric deposition samples will be performed on the "whole water" (unfiltered) sample as is normally done for stream samples. All other total and total recoverable analyses on atmospheric deposition samples will be performed on the material retained on a membrane filter after filtration. Since the filter material will be included in this analysis a background factor will be subtracted from each value. The background value will be determined from a filter from the same batch used for collecting the sample. The Central Laboratory is being asked to make preparations for handling this type of sample. In the following discussion appropriate distinctions will be made between urban hydrology samples and others. Wet-deposition samples should normally be collected on a storm event basis rather than composited over a number of storms. Composite samples from minor wet deposition events preceding major storm events may be composited in an urban hydrology study even if the minor events were insufficient to cause runoff. Dustfall samples should be removed from the collector on a frequency of not less than once every two months, but monthly collections are recommended. If deposition rates are sufficiently large, a higher frequency of collection nay be useful in special cases. In any case, adequate material for the analysis of all required constituents within appropriate detection limits must be provided; otherwise, "less than" detection limit values will have to be reported. This may require some dry runs to determine the minimal amount of material required. The dustfall material is removed from the collector by sequential rinsing with small volumes of deionized water (preferably supplied by the Central Laboratory to standardize matrix effects) from a wash-bottle containing a known volume of water (250 ml recommended) and alternate scrubbing with a clean flexible spatula made of such material that the introduction of extraneous trace metals or organics is minimized. Before rinsing the walls of the collector, large pieces of organic material, such as leaves and insects, should be removed with tweezers. Samples that have noticeable bird droppings should be discarded because leaching of bird droppings and other organic material by accidental water in the dry collector could seriously mask the chemistry of the dry- deposition material. Analytical data for all dry deposition samples should be scrutinized carefully for any indication of contamination. The important point to remember is to insure a quantitative transfer of all sample material in the bucket to the cone splitter. The resulting sample will have a water volume which will be the sum of any wet deposition accidentally accumulated in the dry collector (which can be considerable in some cases) during the sampling interval and the volume of deionized water added. The volume of deionized water added and the resulting sample volume must be determined accurately, preferably by weighing, but an accurate graduated cylinder will suffice. The Ohaus lll9D triple beam scale (about $300) is recommended by the National Atmospheric Deposition Program (NADP). This unit is rugged and can handle up to lOkg +/- 1 to 2g. Once the final wet deposition or dustfall sample is obtained and the volume accurately determined, the following procedures are followed: 1. Use cone splitter to obtain uniform subsamples for each bottle type required by laboratory including an extra bottle for field analysis of pH, conductivity, and alkalinity, if needed. For each dustfall sample collected, be sure to include a separate bottle for a total solids determination because the individual constituent analyses on the dustfall sample can not be run without the total solids value. 2 Field analyses - if the wet deposition has a conductivity of 50 umhos or less follow the procedure outlined in QW Branch Tech Memo 80.19 for determination of pH in low conductivity waters. 3. Unfiltered samples Urban Hydrology - acidify, preserve, or chill appropriate bottles as you would a regular "whole-water" stream sample. Ship samples to laboratory specifying that analyses are to be run on "whole-water" sample. Other programs - acidify, preserve, or chill appropriate bottles as you would a regular "whole-water" stream sample. Ship bottles to laboratory specifying that analyses are to be run on the residue retained on a membrane filter (laboratory will do filtering). 4 Filtered dust-fall samples - prior to filtering add preservative to nutrient bottles and then allow all bottles to be filtered to sit chilled for 24 hours. After filtering, acidify appropriate bottles and continue to chill nutrient bottles. 5. Filtered wet deposition samples - same procedure as for filtered stream sample. 6. The sample log-in sheet and any field note sheet will contain the following information to be used by the laboratory to process the samples and input the data into the computer. a. begin time and date of collection b. end time and date of collection c. volume of deionized water added to dry deposition sample d. resulting volume of dry deposition sample (wet deposition and deionized water added) e. volume of wet deposition collected f. sample type (wet deposition or specific dry deposition component (e.g. dustfall) g. collection areas of wet and dry deposition collectors h. wind velocity (WATSTORE code 00035), optional DATA PROCESSING Additional values for WATSTORE parameter code 72005 (sample source code) will be requested so that an atmospheric deposition sample can be uniquely identified as such, thus allowing the sample source code to be used as a retrieval parameter. Wet deposition, dustfall, and other potential dry deposition components will each have its own value for this code. Additional site specification data can be supplied in the station-name field of the WRD Station Header File. Wet and dry deposition samples will be stored as separate analyses in the Water-Quality File. Analytical results for wet deposition samples will be stored in the computer using the same parameter codes and units as stream samples. For dry deposition samples new parameter codes will have to be requested and the units will be mass of constituent per mass of total dry deposition material, similar to the units used for constituents in stream bottom material. Because dry deposition samples are delivered to the laboratory as solutions it will be essential that one of the analyses for each sample be 'solids, residue at 105 DEG C, total in dry deposition'. The laboratory computer will compute the correct constituent concentration using the concentrations of the individual constituent and total solids in the sample solutions supplied to the laboratory as follows: constituent, dissolved from constituent, solids, residue dry deposition = dissolved ./. on evaporation X 1000 mg ug mg ug mg __ / __ __ / __ __ kg kg L L L constituent, total, in constituent, solids, residue dry deposition = total ./. on evaporation X 1000 mg ug mg ug mg __ / __ __ / __ __ kg kg L L L constituent, constituent, constituent, insoluble in total, in dissolved from dry deposition = dry deposition - dry deposition mg ug mg ug mg ug __ / __ / __ / __ __ / __ kg kg kg kg kg kg Parameter codes for the following list of constituents will be requested from EPA. Additional codes will be requested on a need basis. Constituents marked with an asterisk (*) will not be stored but will be computed upon request for output purposes. The list below does not include codes for insoluble or total forms of nitrate, nitrite, nitrate plus nitrite, chloride, sulfate, carbonate, or bicarbonate because these constituents are assumed to be completely dissolved out of a sample when it is exposed to water as is done in the field preparation procedure. The laboratory procedure for both a filtered sample and an unfiltered sample for these constituents is the same in that there is no preanalysis digestion of either type of sample. R.J. Pickering Chief, Quality of Water Branch Enclosures Key Words: Water Quality, Information, Data Handling, Sampling, Atmospheric Deposition WRD Distribution: A, B, S, FO, PO. Superseded Memoranda: None PARAMETER CODES TO BE REQUESTED wet deposition - sample source code (72005) value dustfall - sample source code (72005) value collector efficiency, wet deposition collector efficiency, dry deposition solids, sum of constituents, dissolved from dry deposition (mg/kg) solids, sum of constituents, insoluble in dry deposition (mg/kg)* solids, sum of constituents, total in dry deposition (mg/kg) solids, residue at 105 DEG C, dissolved from deposition (mg/kg) solids, residue at 105 DEG C, insoluble in dry deposition (mg/kg)* solids, residue at 105 DEG C, total in dry deposition (mg/kg) nitrogen, nitrate, dissolved from dry deposition (mg/kg as N) nitrogen, nitrate, dissolved from dry deposition (mg/kg as N03)* nitrogen, nitrite, dissolved from dry deposition (mg/kg as N) nitrogen, nitrite, dissolved from dry deposition (mg/kg as N02)* nitrogen, nitrite + nitrate, dissolved from dry deposition (mg/kg as N) nitrogen, ammonia, dissolved from dry deposition (mg/kg as N) nitrogen, ammonia, dissolved from dry deposition (mg/kg as NH4)* nitrogen, ammonia, insoluble in dry deposition (mg/kg as N)* nitrogen, ammonia, insoluble in dry deposition (mg/kg as NH4)* nitrogen, ammonia, total in dry deposition (mg/kg as N) nitrogen, ammonia, total in dry deposition (mg/kg as NH4)* nitrogen, ammonia + organic, dissolved from dry deposition (mg/kg as N) nitrogen, ammonia + organic, insoluble in dry deposition (mg/kg as N)* nitrogen, ammonia + organic, total in dry deposition (mg/kg as N) nitrogen, organic, dissolved from dry deposition (mg/kg as N)* nitrogen, organic, insoluble in dry deposition (mg/kg as N)* nitrogen, organic, total in dry deposition (mg/kg as N)* nitrogen, total, dissolved from dry deposition (mg/kg as N)* nitrogen, total, insoluble in dry deposition (mg/kg as N)* nitrogen, total in dry deposition (mg/kg as N)* phosphorus, total, dissolved from dry deposition (mg/kg as P) phosphorus, total, dissolved from dry deposition (mg/kg as P04)* phosphorus, total, insoluble in dry deposition (mg/kg as P)* phosphorus, total, insoluble in dry deposition (mg/kg as P04)* phosphorus, total in dry deposition (mg/kg as P) phosphorus, total in dry deposition (mg/kg as P04)* phosphorus, orthophosphate, dissolved from dry deposition (mg/kg as P) phosphorus, orthophosphate, dissolved from dry deposition (mg/kg as P04)* phosphorus, orthophosphate, insoluble in dry deposition (mg/kg as P)* phosphorus, orthophosphate, insoluble in dry deposition (mg/kg as P04)* phosphorus, orthophosphate, total in dry deposition (mg/kg as P) phosphorus, orthophosphate, total in dry deposition (mg/kg as P04)* sodium, dissolved from dry deposition (mg/kg) sodium, insoluble in dry deposition (mg/kg)* sodium, recoverable from dry deposition (mg/kg) potassium, dissolved from dry deposition (mg/kg) potassium, insoluble in dry deposition (mg/kg)* potassium, recoverable from dry deposition (mg/kg) calcium, dissolved from dry deposition (mg/kg) calcium, insoluble in dry deposition (mg/kg)* calcium, recoverable from dry deposition (mg/kg)* magnesium, dissolved from dry deposition (mg/kg) magnesium, insoluble in dry deposition (mg/kg)* magnesium, recoverable from dry deposition (mg/kg) chloride, dissolved from dry deposition (mg/kg) sulfate, dissolved from dry deposition (mg/kg) carbonate, dissolved from dry deposition (mg/kg) bicarbonate, dissolved from dry deposition (mg/kg) carbon, organic, dissolved from dry deposition (mg/kg as C) carbon, organic, insoluble in dry deposition (mg/kg as C)* carbon, organic, total in dry deposition (mg/kg as C) carbon, inorganic, dissolved from dry deposition (mg/kg as C) carbon, inorganic, insoluble in dry deposition (mg/kg as C)* carbon, inorganic, total in dry deposition (mg/kg as C) lead, dissolved from dry deposition (ug/kg) lead, insoluble in dry deposition (ug/kg)* lead, recoverable from dry deposition (ug/kg) cadmium, dissolved from dry deposition (ug/kg) cadmium, insoluble in dry deposition (ug/kg)* cadmium, recoverable from dry deposition (ug/kg) copper, dissolved from dry deposition (ug/kg) copper, insoluble in dry deposition (ug/kg)* copper, recoverable from dry deposition (ug/kg) zinc, dissolved from dry deposition (ug/kg) zinc, insoluble in dry deposition (ug/kg)* zinc, recoverable from dry deposition (ug/kg) chromium, dissolved from dry deposition (ug/kg) chromium, insoluble in dry deposition (ug/kg)* chromium, recoverable from dry deposition (ug/kg) iron, dissolved from dry deposition (ug/kg) iron, insoluble in dry deposition (ug/kg)* iron, recoverable from dry deposition (ug/kg) arsenic, dissolved from dry deposition (ug/kg) arsenic, insoluble in dry deposition (ug/kg)* arsenic, total in dry deposition (ug/kg)