Environmental monitoring and recommendations on decreasing the levels of pesticide pollution in Zhytomyr region of Ukraine

Environmental monitoring was conducted of facilities for storage and disposal of banned and unsuitable pesticides. Pesticide content in the soil, water, and products of agriculture in the Zhytomyr region of Ukraine was examined, and the accumulation of organochlorine pesticides by freshwater bivalve mollusks was assessed. Storage facilities of the Zhytomyr region contain nearly 392.18 t of pesticides in 137 warehouses, of which 11 meet the requirements, 36 are tolerable, and 90 are in poor condition. In 2018–2019, pesticide content (dichlorodiphenyltrichloroethane (DDT), heptachlor, dichlorodiphenyldichloroethylene (DDE), dichlorodiphenyldichloroethane (DDD), hexachlorocyclohexane (HCH)) was studied in soil and sediments in the Zhytomyr region. The content ranged from 0.0007 to 0.07 mg/kg, which is lower than MPC (0.1 mg/kg). The content of HCH, DDT, DDE, DDD, and heptachlor was at 0.0007–0.01 mg/dm3 levels in water bodies of the Zhytomyr region in 2018–2019, also lower than MPC. In some samples of soil, water and vegetables, the recorded levels of DDT and organophosphate pesticides Dragon, Dorpan, and Dursban exceeded MPC in 1.5–3.0 times. Traces of organochlorine pesticide Aldrin were found in soft tissues of bivalve mollusks and in the sediments of water bodies they inhabit. Recommendations are proposed to lower the pesticide content in the environment.


Introduction
Ukraine has ratified the Stockholm Convention (23 May 2001) with the Law of Ukraine N 949-V (949-16) of April 18, 2007. According to the Convention, persistent organic pollutants (POP) are recognized as toxic, resistant to decomposition, bioaccumulative, and are subject to transboundary movements by air, water and with migrating species. POP is also deposited at a great distance from the source of their emission, accumulating in terrestrial and aquatic ecosystems [1]. By this convention DDT, aldrin, dieldrin, endrin, chlordane, mirex, toxaphene, heptachlor are included in the list of most dangerous substances.
Long-term application of pesticides has led to largescale environmental pollution over huge territories. The migration of toxic compounds in ecosystems causes the accumulation of residual amounts of pesticides in natural objects.
In Ukraine, OCP has been used most extensively in the 1950-1960s. At the beginning of the 1970s, OCP was shown to be highly toxic to animal organisms. They are also very persistent. DDT does not decompose in the environment for 10 years [6]. When from the environment (soil, water, sediments) OCP enter the living organisms, the compounds circulate in trophic chains of local ecosystems, climbing the trophic levels. Thus, all these components of ecosystems, from producers to consumers of highest levels, contain pesticides in their bodies. DDT and HCH can accumulate in various organs and tissues (in the case of DDT, mostly in fat tissue). OCP is polytropic compounds, thus they are significantly dangerous to human and animal organisms even in small doses. They negatively affect the functional state of the liver, glands, kidneys and other organs. They have also cytotoxic, carcinogenic, mutagenic effects. All this led to the restriction or ban of their use in the early 1970s. But even today, OCP belongs to the category of widespread pollutants both in Ukraine and abroad.
Content of DDD, DDT, DDE, HCH, DDVP (dichlorvos), 2,4-D (2,4-dichlorophenoxyacetic acid) has been analyzed in rivers of Luhynsky district of Zhytomyr region in 1988-2008. The results of the analysis indicated a significant decrease in pesticide content in the two decades [4]. That is linked to the discontinuation of large agricultural enterprises that had used public funds to purchase pesticides. At present, only small farms and private homesteads operate in the district.
The long-term, often uncontrolled and unjustified, use of pesticides in agriculture has led to the contamination of inland water bodies with these dangerous toxicants and the disturbance of natural ecological balance. Pesticides of different chemical origin have a detrimental effect on all representatives of freshwater biota. Due to the cumulative properties, pesticides circulate and accumulate in the organisms of all aquatic organisms, including shellfish. In the early XXI century, several scientists [6] have registered persistent OCP (DDT and HCH) in various organs of six freshwater mollusk species of the family Unionidae in rivers of Zhytomyr and Khmelnytskyi regions.
Today, organophosphate pesticides such as chlorophos, paraoxane, metaphos, carbofos, oxamethyl are used more and more frequently [3]. They are less toxic than OCP and do not withstand water, i.e. they are subject to rapid decomposition, which eliminates their prolonged impact on the biota of reservoirs. Today it is important to monitor both the storage conditions of pesticides, a lot of which are still kept in the Zhytomyr Region of Ukraine [15], and the pesticide content in the soil, water bodies, products of agriculture, and in aquatic organisms.
Study aim: to conduct ecological monitoring of pesticides in the Zhytomyr region and to prepare recommendations on decreasing the pesticide levels in the environment.
The study subject is the ecological monitoring of pesticides in the Zhytomyr region.
The content of pesticides in water, soil, agricultural products and tissues of mollusks was determined based on the State Institution "Zhytomyr Regional Laboratory Center of the Ministry of Health of Ukraine" using standard methods of OCP research, gas-liquid chromatography, and thin-layer chromatography:   Information about pesticide storage was given by the Department of Ecology and Natural Resources of Zhytomyr Region State Administration.
Bivalve mollusks were sampled manually at a maximum depth of 0.5-0.7 m [19]. Most mollusks live on sediments (silt, sandy silt), rarely on sands. Species identification of mollusks was performed based on their conchological features [20].
The results of the study were processed using methods of variation statistics [21].

The problem of pesticide storage facilities in Zhytomyr region
Numerous warehouses were built in almost all regions of then-Soviet Ukraine to store various types of pesticides (herbicides, fungicides, insecticides, acaricides, zoocides, etc.). Usually, such pesticides are stored in significantly damaged packages, contaminate the soil and seep into the groundwater. Hence, warehouses that contain pesticides are extremely dangerous. They also have no warning signs and are largely unsecured.
One of the acute environmental problems in the Zhytomyr region is the practice of dealing with unsuitable pesticides and agrochemicals. According to the Department of Ecology and Natural Resources of Zhytomyr Region State Administration, 137 warehouses with unsuitable pesticides and agrochemicals are in the Zhytomyr region, as of 01.01.2018 (Fig. 3). Eleven warehouses meet the requirements, 36 are tolerable, and 90 are in poor condition (Fig. 4, 5). The largest warehouses are located in Yahodynka village (Pulynsky district), with 23.00 tons of pesticides; N. Velidnyky village (Ovrutsky district), with 19.49 tons of pesticides at OJSC "Ovrutsky rajagrokhim"; Koshelivka village (Pulynsky district), with 17.0 tons of pesticides; Veselivka village (Ovrutsky district), with 12.07 tons of pesticides at LLC "Nehodivske".  There are a total of 392.18 t of stored pesticides. Of these, 32.450 t are liquid, 24.975 t are solid, and 334.755 t is unknown mixtures. The condition of the storing containers is as follows: 39.07 t of pesticides are kept in good condition, 22.43 t in satisfactory condition, the rest in poor condition. Due to poor storage conditions, toxic pesticides enter the environment including water and air, presenting the risk of poisoning to humans, flora, and fauna. In 2011-2012, 968.535 t of unsuitable CPPP were reloaded and exported from Ukraine. At present, the territory of Baranivsky, Brusyliv, Lubarsky, Malynsky, Romanovsky, and Ruzhyn districts of the Zhytomyr region has been cleared of CPPP.
Expired pesticides are unusable and must be disposed of. Together with storage packaging, they are hazardous waste that must be correctly deactivated by licensed agencies. Currently, in Ukraine, there are no entities licensed to conduct hazardous-waste management (collection, transportation, storage, treatment, disposal), including unsuitable pesticides.
The problem also lies in the lack of a scientifically sound concept of pesticide processing and deactivation, imperfect technological processes and the incomplete technological cycles of processing, the lack of safe methods of disposal. The whole range of issues related to the elimination or control of the negative effects of toxic waste on the environment and human health will only be effectively resolved with a national program for waste management.

Pesticide pollution of soil, water bodies and products of agriculture in Zhytomyr region
According to State Institution "Zhytomyr Regional Laboratory Center of the Ministry of Health of Ukraine", pesticide (HCH, DDT, DDE, DDD, heptachlor) content was in the range of 0.0007-0.07 mg/kg in soils and sediments of Zhytomyr region in 2018-2019, within the MPC values (0.1 mg/kg) ( Table 1).  compounds. It is a modern, broad-spectrum contact insecticide against sucking and biting insects. It has high initial toxicity, blocking primarily acetylcholine esterase enzymes, which play an important role in the transmission of nerve impulses in insects.
Content of HCH, DDT, DDE, DDD, and heptachlor was measured in water bodies of the Zhytomyr region in 2018-2019 (according to the Zhytomyr Regional Laboratory Center of the Ministry of Health of Ukraine). It fluctuated in the range of 0.0007-0.01 mg/dm3, which is within MPC values ( Table 2).

Accumulation of organochlorine pesticides by freshwater bivalve mollusks
We studied the organochlorine pesticide content in soft tissues of bivalve mollusks of the species Unio crassus from the Perha river (Radovel' village, Olevsky district) and Anodonta anatina from Irsha river (Khoroshiv village, Zhytomyr region), and also in water and sediments of rivers inhabited by the mollusks. OCP enters the mollusk organisms the same as other pesticides, either through the skin, adsorption with food, or with metabolism. OCP is accumulated most intensively in the body parts of mollusks that are most exposed to the polluted environment (shell, mantle, foot, and branchia).
HCH, DDT, DDD, DDE, heptachlor were not detected in water, sediments, and tissues of bivalve mollusks by gas-liquid chromatography. Thin-layer chromatography revealed traces of Aldrin pesticide in sediments and soft mollusks (Fig. 6). Aldrin is a pesticide, used in pest control in plant cultures and against termites. Due to its toxic effect, it is banned not only for use but also for production in Ukraine and many other countries of the world. At the same time, Aldrin reserves may be kept in numerous pesticide storages in Ukraine.

Recommendations for decreasing pesticide content in the environment
The development of scientific technologies and legislative framework is important in controlling and lessening the negative effects of pesticides on the environment. Hence, the following recommendations are topical: -the implementation of the Stockholm Convention on Persistent Organic Pollutants in Ukraine should become a matter of national priority; -there should be scientific studies and development concerned with the determination and monitoring of pesticides; -system of state monitoring of environment and citizen health under the effect of pesticides should be implemented; -the infiltration of pesticides into the environment should be limited and/or prevented; -control should be established over economic entities that produce and sell (or otherwise realize) pesticides, and over citizens or other legal entities engaged in activities related to such pesticides; -people of Ukraine should be informed of the dangers of pesticides; -training programs should be developed and implemented on pesticide hazards and their implications for the life and health of humans, the environment, and of alternatives to pesticides; illegal circulation of pesticides in Ukraine, circulation of banned and overdue pesticides should be prevented, and areas contaminated with pesticides that are unsuitable or banned to use should be detected and cleared.

Conclusions
In