Project Title: Atmospheric Deposition of Currently Used Pesticides to the St. Jones River Reserve and Upper Delmarva Peninsula
Principal Investigator(s): Alba Torrents and Laura McConnell

Accomplishments
Scheduled Tasks:
For the reporting period, we had proposed two main tasks:

1. Collection of weekly air samples and daily precipitation samples from the three collection sites.
2. Analysis of achieved samples from previous year.
3. Collection of data to facilitate determination of fluxes.

Progress on Tasks
Task 1 has been conducted as scheduled. The new rain and air samplers at St. Jones River Reserve, DE were installed in April. The new site is located on the property of DNERR in a marshy area (see Figure 1).

For Task 2, The analysis of pesticides present in the dissolved phase of rainfall was carried out on samples from Cambridge. At present results are available only for insecticides + fungicides. Results for herbicides are expected soon as well as the analysis of the samples for the other two sites.

In order to gather additional information to determine fluxes and relative significance (Task 3), a cruise on the Choptank River was undertaken on 4th June, 2002 to collect surface water and sediment samples at various points along the length of the river. Samples were also collected from two points further upstream on the previous day. The water samples will be analyzed for pesticides as well as certain pesticide metabolites. The sediment samples, in addition to being analyzed for pesticides, will also be tested for the presence of certain metals.

Due to increased concerns on the deposition of PAH's and the fact that our samples represent a unique collection, we have included the analysis of PAH's . The PhD student has spend big part of her summer developing PAH’s methodology and a GC-MS method is almost ready.

Difficulties Encountered
While we are a bit behind on the sample analysis, we have surpass the main difficulty of installing new samplers at DOVER.

Anticipated Success in Meeting Project Objectives in Scheduled Project Period
Work is being conducted as planed.

Preliminary Results
There were 40 significant rain events in all during the sampling period (beginning of April to end of October). Of the 19 analytes, chlorothalonil and endosulfan II were detected most frequently (93 % of the times). These were closely followed by a-endosulfan and endosulfan sulfate (detected 90 % of the time). _-HCH, oxychlordane, p,p-DDE and p,p-DDT were either not detected or were below the level of quantification.

As can be expected, high concentrations of these compounds are generally seen in the summer months. The combined maximum concentration (568 ppt) was on 1st July. The endosulfans and chlorothalonil are the only compounds with significant concentrations after summer. Some of the reported data is summarized in Figure 2.

The organochlorine insecticides, g-HCH and the endosulfans were detected the year round. For g-HCH the concentrations are higher during summer months. As in the previous year, a-HCH was below the level of quantification. Since a-HCH results mainly from the photochemical conversion of g-HCH in the atmosphere, the non-detection/quantification of a-HCH would suggest that rain out occurs before significant conversion can occur. However, a-HCH has been found to occur in considerable concentration in air samples last year. So, the non-detection of a-HCH in rain is probably due to its low Henry's constant.

The three endosulfans ­ a-, b- and the metabolite endosulfan sulfate, follow similar trend. The highest concentration occurs from summer to early fall. In early summer/late spring the concentration of metabolite is higher. Thereafter, the a- and b- endosulfan predominate. This is in keeping with the expected ­ the parent compounds predominate during the application season and the metabolite at other times. This also seems to suggest relatively quick conversion of the parent compounds. One surprising result, however, is that the concentrations are about a tenth compared to last year's. The reason for this needs to be looked into.

The chlordanes, both a- and g-, appear to have similar trend in concentration and were not detected after summertime. The DDTs present an interesting case. Neither the metabolite p,p-DDE nor the p,p-DDT was detected. Only o,p-DDT was detected twice. This suggests local application of the DDT. Oxychlordane was below the level of quantification. The detection frequency of g-chlordane was high (55 %) but the concentrations were low. On the other hand, a-chlordane had a low detection frequency (20%). The two compounds had highest concentrations in different times of the year ­ g-chlordane peaked in April while a-chlordane in summer.

The organophosphorus insecticide, malathion, was detected throughout the year although the highest concentration was reached in summer. Diazinon was detected only twice. It might be mentioned that in most samples diazinon was below the level of quantification. Chlorpyrifos was detected in 75% of the samples although concentration as quite low in the latter part of the year. Chlorpyrifos oxon was found to have much higher concentration than chlorpyrifos but was not detected after mid June.

The nonachlors were detected only upto summer with the highest concentrations in spring. Most of the concentrations were low, around 0.1 ppt. Trifluralin (a herbicide) had low detection frequency (10%) and most of the concentrations were below 1 ppt. The highest concentration (7.35 ppt) occurred in April. This might suggest that the detection is due to local usage.

The fungicide, chlorothalonil, had the highest detection frequency (93%) and the highest concentration of all the compounds ­ a high of 509.86 ppt (in July). The concentrations were typically higher in the latter part of the year (summer and beyond) which is in keeping with application trends. However, due to the unavailability of the rain sampler from mid July to mid August, the real highest concentration might have been lost. The maximum concentration this year is more than twice as high as the maximum concentration for the last year (about 200 ppt, also in July). This does not imply an increase in usage but rather has to do with the timing and amount of rainfall.

The foregoing is an incomplete picture of the pesticide load to the area of study as the samples have not been analyzed for the presence of herbicides. Also pesticides have been analyzed for only in the dissolved phase. A more coherent picture would emerge after both the air and rain samples have been analyzed. Also the data from the second site, Lewes, would enable us to study the change in the areal distribution of pesticides within a relatively small area. A comparison of the data from the two years (2000 and 2001) should shed some light on the temporal distribution of the pesticides.

Once the required analyses have been carried out on the physical samples, it would be interesting to study the gas-particle phase distribution of pesticides. Various factors such as humidity, particle size etc can influence how much of the compound settles on the particle and how much remains in the gaseous phase. Another aspect that should be looked into is the distribution of the compound between the rain and gaseous phase under given conditions. In order to understand the fate of such heavily used chemicals as pesticides in the atmosphere, it is imperative that the factors affecting the distribution of these compounds in gaseous, particulate and dissolved phase be studied.

Tasks and activities for next reporting period

Tasks for the next reporting period
The foregoing is an incomplete picture of the pesticide load to the area of study as the samples have not been analyzed for the presence of herbicides. Also pesticides have been analyzed for only in the dissolved phase. A more coherent picture would emerge after both the air and rain samples have been analyzed. Also the data from the second site, Lewes, would enable us to study the change in the areal distribution of pesticides within a relatively small area. A comparison of the data from the two years (2000 and 2001) should shed some light on the temporal distribution of the pesticides.

Once the required analyses have been carried out on the physical samples, we will study the gas-particle phase distribution of pesticides. Various factors such as humidity, particle size etc can influence how much of the compound settles on the particle and how much remains in the gaseous phase. Another aspect that should be looked into is the distribution of the compound between the rain and gaseous phase under given conditions. In order to understand the fate of such heavily used chemicals as pesticides in the atmosphere, it is imperative that the factors affecting the distribution of these compounds in gaseous, particulate and dissolved phase be studied.

Work plan to accomplish tasks
The PhD student hsa finish her course requirements and will be working full time on this project. We will develop protocols to analyze PAH's and to conduct gas-particle phase distribution studies. Sampling will be conducted as scheduled (air) and as weather dictates (rain). Sample extraction, analysis and data analysis will be conducted as scheduled.

Concerns or difficulties
At this point, we have no concerns or difficulties.

Expenditures
Up to date, only funds transferred to collaborators and equipment purchase had been used. Student working on this project has been supported by a fellowship and remaining WRRC funds but soon her stipend will go full-time on this project. Expenditures are accordingly low but will soon catch up to the scheduled plan.

As proposed in the prior report, funds allocated to be transferred to St. Jones to help on the technical support were re-routed to help them in the purchase of a piece of equipment, this facilitated the transfer and reduced administration costs.