31. Pesticides in Danube River and Tributaries

by Dr. Fina Kaloyanova-Simeonova

In the Strategic Action Plan for the Danube river basin 1995-2005 agriculture is recognized as source of chemical pollution of surface and ground water. The target up to year 2000 is significant restructuring of pesticide use per unit land under production and conversion of farmers to methods of integrated pest control, at least in all areas of importance for nature conservation. The ultimate goal is to achieve an agreement between countries on pesticides which are allowed, conditions under which pesticides may be applied especially related to protection of ground and surface water -criteria for allowance of pesticides use with regard to ecotoxicological aspects. PHARE Project Danube Regional Pesticide Study was initiated with Service Contract 95.0100, PHARE ZZ 9111/0106. The project started May 1995 and finished 1997 /Tasheva 1997/. A Consortium of three countries - Bulgaria (leading country). Hungary and Slovak Republic and consultants from other 8 Danube region countries (Austria, Croatia, Czech Republic, Germany, Moldova, Romania, Slovenia, Ukraine) participated in this study.

LITERATURE REVIEW OF THE EXISTING CONCENTRATIONS OF PESTICIDES IN WATER AND IN AQUATIC LIFE

The pollution of surface water by pesticides may occur mainly by four different routes:

1/. Run-off after spraying the crops.

2/. Drifts /overspray/ to waters nearby the treated fields and atmospheric deposition.

3/. Direct water treatment by herbicides to destroy water weeds or by insecticides for vector control.

4/. Drainage /leaching/.

Factors affecting the transport and fate of pesticides are crops, tillage practice, soil properties, atmospheric, geologic and hydrologic regimes. After spraying the most of the pesticides are deposited on vegetation, soil or other surfaces. Deposits on soil remain in the top few centimeters, where they degrade or become adsorbed on the soil and organic particles. Only a very minor fraction contaminates surface and groundwater sources and causes concern in aquatic toxicology and drinking water quality. This is connected with pesticides water solubility and persistence, but water also transports soil particles on which pesticides have been absorbed.

Pesticide misuse, spillage or inappropriate storage and handling facilities and disposal, has been estimated to be responsible for approximately 50% of the water contamination incidents in USA /Ritter 1990, cited by Carter 1993/.Concentrations of pesticides in water are subject of many monitoring programs around the world.

Pesticides in water were monitored in UK in 1992. The number of samples exceeding the standard 0.1 mg/l was 3% . Herbicides atrazine, simazine, diuron, isoproturon and mecoprop represented 96% of the positive samples. Other herbicides also have been found as follows: TCA, chlortoluron, dalapon, MCPA, and 2,4-D. Some of these herbicides are used predominantly in non-agricultural situations. /Carter 1993/

In the Netherlands the upper groundwater below vulnerable soils was analyzed for nearly 2.5 years in 8 sampling rounds. Of 18 compounds analyzed 1,3-dichlorpropene, aldicarb, ethoprophos, dinoseb, metamitron, atrazine, desethyl- and desisopropylatrazine, metolachlor and ethylenethiourea were repeatedly detected in the groundwater in concentrations above 0.1 microgram/l, the EC limit for drinking water. / Loch and Verdam 1989/.

Between May and early July samples of treated water were collected after rainfall from 33 water supplies using surface water sources. Individual pesticides and number of supplies in which they were detected were: atrazine-30, cyanazine /Bladex/-26, metolachlor, Dual/-21, alachlor /Lasso/, carbofuran /Furadan/-9, metribuzin /Sencor/-4, 2,4-D-2, trifluralin /Treflan/, butylate /Sutan/ and dicamba /Banvel/ 1 each /Wnuk et al 1987/.

Johnen /1990/ reviewed the "worst case" residue program in ground water and raw water carried out in Germany and Switzerland in 1987/88 and 1985/88 respectively. In German programs atrazine was found at levels 0-0.26 mg/l, pyridate 0-0.3 mg/l, bentazone 0-0.85 mg/l, chloridazon 0-0.19 mg/l, mecoprob-0.37 mg/l, 1,2-dichloropropane 0-5.1 mg/l, and simazine 0-0.14 mg/l. Atrazine was found at levels 0-0.5 mg/l, desethylatrazine 0-0.4 mg/l and TCA 0-0.9 mg/l in Swiss program.

Airborne contamination of water was studied by Wright /1994/. Atrazine, simazine and metolachlor were found at substantial levels in surface water with highest levels at the mouth of the Susquehanna /27, 50 and 30 ng/l respectively /.In the first runoff after application to corn maximum concentrations for atrazine were 215, tefluthrin 8, alachlor 88, cyanazine 50 and chlorpyrofos 4 ppb in water phase and in smaller concentrations /5-10 times less/ in sediment phase. In shallow ground water 175 ppb atrazine, 95 alachlor and 65 cyanazine were detected. / Schreiber and Cullum 1993/.

At recommended application rates the concentration of 2-4-D in water has been estimated to be a maximum of 50 mg/l. Most applications would lead to water concentrations much lower than this-between 0.1 and 1 ms/l /EHC 84, 1989/.

Levels less than 1 mg/l are encountered in the natural aquatic systems after deliberate introduction of the ester formulations for aquatic weed control /2-4-D / or from runoff or drift in terrestrial operations. Rapid hydrolysis of the esters to the acid is usually assumed to minimize the duration of exposure to esters themselves.

The risk for aquatic communities to chlorophenols appears to be low. Assuming 10 mg/l as a typical mean concentration for any of the chlorphenols in U.S. surface waters, the lowest chronic effects level exceeded this concentration by one order of magnitude, while acute LC50's exceeded it by over two orders of magnitude. Maximum concentrations reported are 100 mg/l. It is likely to be associated with industrial pollution.

Chlor-2-Methylphenol as impurity of MCPA / about 0.3%/ and degradation product can enter the environment. It was found in water samples from paddy fields up to 1.4 mg/l (BUA, 1994).

Maximum concentrations of herbicides found in some rivers in Canada are as follows: trifluralin-max.24 ng/l, bromoxynil -113 and diclofop-476 ng/l in June and undetectable at other sampling periods /March-October/. Dicamba and 2,4-D were detected at concentrations less than 100 ng/l throughout most of the sampling period. High levels were found possibly caused by spraying diches or rights way near the river for dicamba 5476 ng/l and for 2,4-D 2568 ng/l. /Muir and Grift 1987/.

In Kansas River basin atrazine often exceeded the MPL of 3.0 mg/l established by EPA. Unless research find a scientific solution to the safe and effective use of atrazine its long term occurrence in public water sources may pose the threat to aquatic life and to human health through ingestion of contaminated drinking water supplies. / Pope 1993 /.

Mean monthly atrazine concentrations in 1993 in surface runoff were in May, June and July 46, 47 and 7 ppb respectively and ranged in stream flow less than 1 to over 200 ppb / Alberts et al 1994/. During early summer stream flow concentrations of atrazine were >40 ppb /Prato et al 1994/.

Metolachlor in surface water collected 4 weeks after application ranged from 0.01 to 0.13 ppb and in wells from 0.01 to 0.19 ppb /Skaggs et al 1994, Leydy 1994/. Concentrations in surface and ground water of propachlor in USA were consistently low, the maximum being at 10 mg/l in surface and 0.12 mg/l in ground water. The highest water concentration recorded in runoff study was 46 mg/l /EHC 147, 1990 / . In ground water atrazine was detected at 0.08 to 0.48 mg/l /Dowdy et al, 1994/, 6 ppb/l at deeper ground water /3 m/ within 2 weeks after application and alachlor 5 ppb /Cooper and Cullum, 1993/, maximum concentration 0.7 ppb when management practice to reduce contaminate transport was used / Baker and Melvin 1993/.

Pesticide contamination on ground water though at relatively low concentrations, is relatively common in areas of intensive farming or near hazardous waste disposal sites. USEPA listed 46 pesticides as confirmed ground water contaminants.

Pesticides in ground water were found as follows : in Germany - 36 from 173 looked for , Italy - 39 from 47, Netherlands -26, Denmark - 10, Great Britain-30, Sweden 18./ Fielding et al, 1992, cited by Helveg 1994/. It is very important to distinguish direct pollution due to direct spray of the water, from leaching pollution. It is expected that the direct pollution may create higher concentrations of all kinds of pesticides and will act more by the so called "hurt and run" mechanism, while the leaching after field treatment and from site of filling of sprayers or rinsing the sprayers equipment will create low concentrations of more soluble and persistent pesticides.

Helweg, 1994 summarized published data for water concentrations of pesticides, found in Denmark, as shown:

Rehana et all /1995/ detected in Ganga river DDT- 3.33-5.33 ppb, alpha BHC- 1.73-3.01 ppb, DDD- 0.88-2.41 ppb, aldrin-1.17-2.81 ppb, and dieldrin- 0.49-4.11 ppb. Dua et all /1996/ found in malaria control sprayed area in India in water mean concentrations of DDT- 0.07 mg/l and HCH 0.18 mg/l. Concentrations in soil were respectively 73.3 and 27 times higher. Organoclorines pesticides were detected in sediments from four US Arctic lakes /Allen-Gil et all 1997/ at max. 0.7 ng/g dry wt.

Pesticides concentrations in aquatic life.

Concentrations of organochlorines in nineties are much lower than the levels detected during the late 1970s and early 1980s. A highly insignificant correlation was found between aquatic life age and concentrations.

Some recent data are presented at table 1 .

Table N 1. Pesticides concentrations in aquatic life.

Species Place Concentrations Reference

Aquatic birds Texas DDE-9.65 mg/g Mora 1996

snowy egret eggs DDD-0.056 mg/g

1993-94 DDT-1.75 mg/g

Great blue heron Whidbey Is. DDT less than 0.4 ppm Cobb et all

eggs Washington 1995

Striped dolphins Mediter. DDT-111 m Guitart et all

melon -1990 Spanish coasts g-1 wet wt 1996

Harp seals Greenland p,p=-DDE-760 ng/g w.w. Oehme et all

blubber and sea 1995

brain.

Sturgeon Cooling water DDT and metabolites Bressa et all

24 mo old thermoelectric 28.4 mg/kg d.w. 1996