EFFECTS OF AGROCHEMICALS ON SOIL AND WATER QUALITY IN PARTS OF RIVERS NIGER AND KADUNA CATCHMENTS, NORTH CENTRAL NIGERIA

ABSTRACT

Contamination of soil and surface water due to unsustainable use of pesticides and fertilisers by farmers and subsequent socioeconomic effects on communities’ livelihoods is a major problem in the study area. Comprehensive data on this problem is of great interest as the existing ones are scanty. The objectives are to investigate the patterns of pesticides and fertilisers use; determine the spatial concentrations of physicochemical properties of sediment and water samples; determine the spatial concentrations of plant minerals and the extent of occurrence of organochlorine pesticide residues in water and soil; investigate the socioeconomic challenges; and appraise the effectiveness of relevant environmental laws and extant regulations on agrochemical use in the study area. An extensive field survey was conducted using various participatory appraisal techniques, namely, questionnaires, scheduled interviews, and village-level group discussions. Subsequently, seasonal water and sediment samples was collected, analysed in-situ (for water only) and in the laboratory for physico-chemical properties, plant minerals and pesticide residue concentrations. Collated data were analysed using descriptive statistical methods (frequency percentage), spatial analysis and non-parametric analysis. Survey results indicated that a significant percentage of the study population (97.5%) used synthetic fertilizers in their farming. Percentage volume of fertilizers and pesticide application per hectare indicated that the study population uses high quantities of agrochemicals across the zones. Physico-chemical properties identified in this study showed that the value of pH range (5.2 to 7.4), salinity (28.0 to 76.0 PSU), temperature (22.1 to 28.1 °C), EC (10.0 to 43.0 μs/cm), DO (5.3 to 8.6 ppm), TDS (6.7 to 23.60 ppm), turbidity (12 to 47 0 NTU), COD (13.80 to 45.06 ppm), BOD (7.05 to 18.15 ppm), TSS (15.8 to 54.0 ppm), Mn (0.08 to 2.86 ppm), TH (3.55 to 10.52 ppm), chloride (16.08 to 106.5 ppm), sulphate (0.447 to 22.68 ppm) and potassium (0.13 to 62.75 ppm). Plant mineral concentrations were detected and spatially distributed across the study zones in surface water and sediment samples during rainy and dry seasons, with concentrations ranging from NO3- (0.02 to 3.147 ppm), NO2- (0.02 to 1.16 ppm) and PO4- (0.228 to 5.771 ppm). Organochlorine pesticide compounds which include endosulfan, alpha endosulfan, endosulfan ether, delta endosulfan, endosulfan sulfate, mehoxychlor, alpha lindane, delta lindane, endrin ketone, dieldrin, DDT, DDMU, mitotane and heptachlor epoxide were detected and quantified with concentrations ranging from 0.01 ppm to 15.97 ppm in water and sediment samples analysed. Conclusively, it can be stated that there exist unsustainable patterns of agrochemical use which has obviously led to contamination of water, sediments and socioeconomic effects in the study area owing to weak regulations. Thus, it is recommended that visible and effective environmental management policies in respect of agrochemical use in the study area be put in place. Also, Green chemistry technology should be adapted for agrochemical formulations, organic farming and the use of biobased products should be encouraged and promoted among farmers to minimize or prevent the use of environmental unfriendly agrochemicals. This  will guarantee cleaner and healthier environment for all.

CHAPTER ONE

1.0       INTRODUCTION

1.1       Background to the Study

Agrochemical is a common name for chemicals (pesticides and fertilizers) used in farming to enhance growth and protection of plants. Precisely, they are agriculture chemicals (Leong et al., 2020). Although, they are originally used to increase yields, they have been reported to have negative effects on soil and water quality (Sun et al., 2019; Corcoran et al., 2020). In addition to the obvious effects on plants and food chains, they are widely used. Because of these many uses, they move into the surrounding water, which has a wide range of effects on physical, chemical, and biological processes within aquatic ecosystems (Lakhani, 2015; Bassi et al., 2016; Joko et al., 2017; Kaur et al., 2019).

Modern agriculture depends heavily on the use of chemicals (Sánchez-Bayo and Tennekes, 2017; Sarker et al., 2020). It has been estimated that every year, 150 million tons of fertilizers and millions of tons of pesticides are applied to crop fields globally with the only objective of increasing agricultural production (Bernhardt et al., 2017; Gilbertson, 2020). While there is evidence that the use of herbicides can increase yields in many crops (Gianessi, 2013; Karim et al., 2020), there is also evidence that most fungicides and insecticides do not help increase such yields (Lechenet et al., 2017).

On the other hand, the ecological risks of these chemical inputs to the environment are often ignored by the public, when not dismissed by those who assert that a growing human population needs to be fed at all costs (Popp et al., 2013). Concerns about the massive use of agricultural pesticides, in particular insecticides, in agriculture was raised half a century ago (Sánchez-Bayo and Tennekes, 2017) sparking an environmental movement that has lasted to this day. Regulations about the safety of individual pesticides were enacted in the developed countries in the 1970s, while most developing and underdeveloped countries remained oblivious to their negative effects (Khan et al., 2015) until their routine misuse impacted on human health (Alinejad et al., 2017; Valcke et al., 2017; Ha et al., 2018) and brought about other negative environmental consequences (Scholz et al., 2012).

An environment that is free of pollutants is essential for ideal environmental safety, fitness of human health and economic development (Ja’agi and Baba, 2015). Polluted water due to microbial infections causes visible diarrhoeal diseases, on the other hand, chemical and toxic contaminations result into acute or chronic sicknesses in human and kill insidiously (Wimalawansa and Wimalawansa, 2014). Contamination of water by agrochemicals are a worldwide problem and a serious issue in developing countries, where the difficulties are associated in part to slack environmental laws. Subsequently, water pollution creates an enable avenue of contamination of the human food chain. Water and food are firmly associated and cannot be separated easily. Numerous transmissible and non-transmissible human diseases are often correlated to water, soil- geochemistry, and environmental pollution (Kolpakova, 2004; Wimalawansa and Wimalawansa, 2014).

In addition to degrading the physical, chemical, and biological status of hydrologic systems, pesticides and plant minerals can have significant social and economic costs on communities through polluting drinking water, degrading fisheries, and potentially increasing food risks. Excess nitrogen and phosphates in rivers, lakes, reservoirs, and ponds can lead to massive overgrowth of algae and deplete the oxygen levels that fish, shellfish and other aquatic organisms need for survival (Knauer, 2016). High levels of nitrogen in drinking water can pose particular risk to infants and children. Water pollution arising from pesticide use can affect many non-targeted biotic systems, such as fish, birds, beneficial insects, and plants. An assessment of pesticide residues in sediment, water and living organisms of rivers in agricultural areas in most countries shows that pesticides and other toxic agrochemicals are increasingly polluting the aquatic environment (Lawrence et al., 2015; Lindstrom et al., 2015). As a result of monitoring, pesticide residues are often found in surface waters (Lindstrom et al., 2015), and concentrations of pesticide residues have been reported in several studies that are expected to affect aquatic organisms or communities (Ali et al., 2014; Knauer, 2016; Houbraken et al., 2017).

In Nigeria, agrochemicals (pesticides and fertilizers) are widely used to enhance crop production and productivity, right from farming, storage to marketing, distribution of grain, and in seed dressing before planting (Ogunjimi and Farinde, 2012). Farming is a major occupation in the study area which the communities, mostly depend on for a livelihood. Interestingly, several relevant organizations and bodies have taken constructive initiative towards ensuring sustainable use of agrochemicals in Nigeria. These regulatory and enforcement authorities address mostly key stakeholders in the form of organized groups like farmers, marketers at the registration level devoid of proper monitoring and enforcement.

Studies on pollution of aquatic environment caused by various chemicals have been carried out in several areas in North Central Nigeria and reported by various researchers. A study in fadama area of Minna, Nigeria revealed the presence of residues of pesticides in water and soil samples analysed (Ogbonnaya et al., 2017). A related study also in Tunga-Kawo area irrigation scheme revealed contamination of water by agrochemicals (Jimoh et al., 2003). A study on identification of pollution sources and water quality in Kaduna River in Niger State also indicated the influence of anthropogenic effects on the river (Ogwueleka. 2014). Ojutiku et al. (2016) also worked on phytoplankton distribution and physico-chemical characteristic of Lapai-Agaie Dam in Minna, Niger State, Nigeria. Sidi et al. (2016) worked on assessment of the chemical quality of water from shallow alluvial aquifers in and around Badeggi, Central Bida Basin, Nigeria. The study suggested, however, that continued monitoring is needed as a means of protecting the flood plain aquifers from potential contamination. All these studies were not spatial enough, but approached through laboratory, analytical dimension, and without consideration for community or stakeholder participation.

In view of this important limitation, there exists an excellent opportunity to consider a study with spatial coverage beyond laboratory analytical dimensions. Subsequently, while most of these studies were targeted at investigating the physico-chemical properties, and fertilizer contamination separately, few studies have been done on pesticide contamination. No studies have so far been carried out targeted at comprehensive investigation of the effects of agrochemicals on soil and water quality in parts of Rivers Niger and Kaduna catchments. Thus, with the continuous high influx of agrochemical products from increasing population in areas close to water resources, the magnitude of the problem cannot be underestimated. Unfortunately, there is a lack of sufficient information that represent high risk of agrochemical use effect on soil and water quality in the study area. This informed the need for this research.

1.2       Statement of the Research Problem

Reports has it that the use of pesticides and synthetic fertilizers in farming for crop protection and improvement respectively, compromises soil and water quality and consequently threatens the survival of biota and human health (Mensah et al., 2014). According to Mensah et al. (2014), World Health Organisation (WHO) considers most chemical pesticides to be hazardous. A good number of agricultural pesticides namely endosulfan, endrin and dichlorodiphenyltrichloroethane (DDT) have been banned or restricted for use by many countries owing to environmental and health reasons, yet they are still in use by farmers in developing countries like Nigeria (Keri and Directorate, 2009; Ojo, 2016). Aside pesticides, synthetic fertilizer use in various parts of the developing nations are on the increase (Ramteke and Shirgave, 2012).

Rivers Niger and Kaduna catchments are arable land where people practice farming involving intensive use of agrochemicals (Ogwueleka, 2014). This practice can result into soil and water quality degradation and disproportionate negative consequence on the socio-economic wellbeing of the communities. Due to the threats from unsustainable use of agrochemicals and obvious weaknesses in conservation of aquatic resources measures which has resulted in increase in the negative effects on soil and water and the general environment beyond expectations and rapid increase in human population coupled with change in climate has resulted to a motivating factor for farmers to depend more on agrochemicals in agricultural activities near rivers (Knauer, 2016).

Communities depend on these rivers for the livelihood and lack of research information about the area that represent a risk of agrochemical pollution informed the need for immediate  assessment  of  qualities  of  its  resources  to  guaranty  socioeconomic sustainability. Inadequate information about risk of agrochemical pollution has been reported to be one of the factors responsible for weak legislation coupled with poor enforcement of available legislation in Nigeria (Ojo, 2016). There is presently little research attention on agrochemical effects on soil and water quality in the study area and has resulted to scary research information about the study area that represent high risk of agrochemicals pollution. So far, no research evidence indicating a well targeted and detailed analysis has been done in the study area.

Further, several related researches such as Jimoh et al. (2003); Ogwueleka (2014); Lawrence et al. (2015); Dirisu et al. (2016); Ojutiku et al. (2016); Sidi et al. (2016); Ogbonnaya et al. (2017); Bamigboye et al. (2017); Njoku et al. (2017) have been carried out in North Central Nigeria and other parts of Nigeria, however, all these studies were not spatial enough, but approached through laboratory analytical dimension, and without consideration for community or stakeholder’s participation. In view of this limitation, there exists an excellent opportunity to consider a study with comprehensive spatial coverage beyond laboratory analytical dimensions.

More so, while several studies on chemical contamination of soil and water have been conducted in some parts of the study area such as Jimoh et al. (2003), Ojutiku et al. (2016), and Sidi et al. (2016), which were targeted at investigating physico-chemical properties, plant minerals or fertilizer contamination, fewer studies have been done on pesticide contamination. No studies have so far been conducted which is targeted for comprehensive investigation of physico-chemical properties, fertilizers or plant minerals and pesticide residue contamination, and their socio-economic effects on the wellbeing of communities in the study area altogether. This study was envisioned to bridge this gap.

1.3       Research Questions

(i)        What are the patterns of pesticides and fertilizer use in the study area?

(ii)        What are the spatial concentrations of physicochemical properties of water and sediment samples in the study area?

(iii)     What are the spatial concentrations of plant minerals and the extent of occurrence of organochlorine pesticide residues in sediment and surface water samples in the study area?

(iv)      What are the likely socio-economic problems of pesticide residues and fertilizer contamination of the aquatic environment of communities in the area? And

(v)       How effective are the relevant environmental laws and extant regulations for management of agrochemical use near sensitive and vulnerable areas?

1.4       Aim and Objectives

This study aimed to investigate the effects of agrochemicals on soil and water quality in parts of Rivers Niger and Kaduna catchment, North Central Nigeria. The objectives of the study are to:

(i)        investigate the patterns of pesticides and fertilizer use in the study area;

(ii)        determine the spatial concentration of physicochemical properties of sediment and water samples in the study area;

(iii)      determine the spatial concentration of plant minerals, and the extent of occurrence of organochlorine pesticide residues in sediment and surface water samples in the study area;

(iv)      investigate  the socioeconomic challenges of pesticide residues  and  fertilizes contamination of aquatic environments in the communities; and

(v)        appraise the effectiveness of relevant environmental laws and extant regulations on agrochemical use near sensitive and vulnerable areas.

1.5       Justification for the Study

This study investigated the effects of agrochemical on soil and water quality of communities in parts of Rivers Niger and Kaduna catchments in parts of North Central Nigeria. It was conceived since Rivers Niger and Kaduna catchments are highly affected by intense agricultural activities (Ogwueleka, 2014). Furthermore, considering that the threats of unsustainable uses of agrochemical and weak conservation measures of aquatic resources, leading to more serious negative impact on water and general environment beyond expectation. Also, rapid increase in human population coupled with change in climate has resulted to a more reasons for farmers to use more agrochemicals in farming activities near Rivers (Knauer, 2016). Communities’ dependant on these Rivers for livelihood and lack of research information about the area that represent  a risk of agrochemical pollution informed the need for immediate assessment of qualities of its resources to guaranty socioeconomic sustainability.

It is understood that the unsustainable use of agrochemicals (pesticides and fertiliser) has continued to alter the physico-chemical patterns of water and its resources, which has resulted in poor water quality in the study area. As a comprehensive information on the distribution of water quality parameters in the study area is of great interest, there exists an excellent opportunity to consider a study spatial coverage beyond laboratory analytical dimensions.

1.6       Scope and Limitation of the Study

1.6.1    Scope of the study

This study focused mainly on investigating agrochemical effects on soil and water quality in parts of Rivers Niger and Kaduna Catchments, North Central Nigeria. The study was carried out within four Local Government Areas (LGAs) in the Niger State (Mokwa, Lavun, Katcha and Agaie). It covers the area from Rabba village in Mokwa LGA to Baro in Agaie LGA along River Niger and from Wuya village in Lavun LGA to Muregi along River Kaduna.

1.6.2    Limitations of the study

Within the period of this study, no known comprehensive investigation in respect of plant, mineral contamination, pesticide residue concentrations, socio-economic cost and regulatory roles have been conducted in the study area, which resulted to major hindrance in generating enough background or site-specific literature for the study. Other hindrances in this study were; lack of reference analytical laboratory nearby which informed the consideration of only organochlorine pesticide compounds due to their strong ability to remain undegraded for lengthy time under any environmental conditions as the samples were to be sent far away (Dr Olukoya Research Laboratory, University of Lagos) from their collection point for analysis. It also limited the environmental media analysed to water and sediment; also, there was an initial refusal from some key stakeholders to make input to the work, but this limitation was overcome by educating them on the need for their inputs; permissions were also refused by regulatory and enforcement authorities to take the picture evidences of the interactions.

1.7       Study Area

The study area in this investigation is riverine communities in parts of Rivers Niger and Kaduna catchment areas, North Centra, Nigeria, located within Longitude 3˚30’N and 7˚20’E and Latitude 8˚22’N and 11˚30’N; located at the Guinea Savanah vegetation zone at the north central area of Nigeria (Figure 1.1). Rivers Niger and Kaduna catchments are cultivatable land where much farming is in practice close near the rivers (Ahmed, 2001; and Ogwueleka, 2014).

The landscape border area of the river is flat shaped and swampy. It is characterized by several channels and lakes for floods, particularly in the western part. An important feature aspect of this landscape is quite the existence of a large area of Fadamas, where the rivers flow from the complex of basement to the area of the Nupe sandstone. The floodplains on the Kaduna and Niger Rivers are a few kilometres wide at the border of the Nupe basement, the two main streams of Yanko Iko, Dumi, Ebigi all drain their water into the Niger River (Ahmed, 2001).

The study area was divided into zones (Figures 1.1 and 3.2). Along River Niger, the Upper zone is from a Rabba village in Mokwa Local Government Area (LGA), Middle zone is at Muregi and the Lower zone is after Muregi in Mokwa LGA down to the Baro village in Agaie LGA. A study area along River Kaduna was divided into two zones. Upper zone is from Wuya village in Lavun LGA and the Lower zone from halfway down to Muregi. The communities living in the study area rely mostly on agriculture and fishing for economic survival. These are key leading sector for livelihoods, employment, and significant means for the socio-economic wellbeing of the community dwellers (Ahmed, 2001).

Source: Modified from National Space Research & Development Agency, 2017

1.7.1    River Kaduna

The River Kaduna is a key tributary of the Niger in central Nigeria. The river originates from the northwestern part of Jos in the plateau area of Vom, and flows northwest through Kaduna at altitude of 1500 m above the sea level. Then crossing southern to western parts and south before ending along the 550 km to Niger near Muregi (across from Patigi). The river flows through many villages, towns, and cities. The river is the main source of fresh water in agriculture and has thousands of residents throughout its territory (Ogwueleka, 2014). The river was found to be contaminated by agricultural activities, waste from the textiles and daily industry (Ahmed, 2001; Ogwueleka, 2014; Ja’agi and Baba, 2015).

1.7.2   River Niger

River Niger is a famous river in Nigeria; it is in Niger State. The name comes from the Latin “Niger”, which means “black”. Natives call it by different names such as Edu or Ndaduma in Nupe dialect, ‘Jeliba’ or ‘Joliba’ in Manding dialect which means ‘Great River’. It is called ‘Orimiri’ or ‘Orimili’ in Igbo language, which means ‘great water’.

‘Egerew n-Igerewen’ in Tuareg dialect which means River of Rivers. ‘Isa Ber’ in Songhay dialect which means ‘big River’. Kwara, in Hausa dialect and lastly, it is called ’Oya’ in Yoruba dialect. The name Niger State and Nigeria originated from this river; thus, it is commonly called; The Niger River; or ‘River Niger’ all of which mean the same thing. This river and its catchments provide both domestic and economic values to Nigeria and the neighbouring countries (Ja’agi and Baba, 2015; Ihenacho et al., 2019).

1.7.2.1 Climate of the study area

A climate of River Niger and Kaduna catchments shows significant variability. There is a significant decrease in annual rainfall in the north of more than 160 inches in the Delta region to less than 10 inches in Timbuktu. The top and bottom of the river drainage area with rainfall of more than 50 inches per year. Precipitation decreases at the middle parts with highest amount of evaporation being recorded in the same area (Ahmed, 2001; Amanambu et al., 2019).

1.7.2.2 Hydrology of the study area

As a result of climatic variations, the rivers flood occurs annually at different time in all parts of the basins. High water discharges occur in June in the upper parts, and low water season occurs during December. In the mid parts of the rivers, high water discharge that is the white flood type (so called because the sediment content of the water is light) occurs between July and October, soon after the rainy season. Also, black flood (so called because the sediment content is greater) which is the second rise, starting in December upon arrival of flood waters from the upstream part (Ahmed, 2001; Amanambu et al., 2019).

Low-water months at the mid parts stretch occur between May and June annually. Only one high-water season occurs in Benue. Due to the southerly location of Benue, it usually occurs between May and through October, much earlier than the middle parts. Higher water period of River Niger which normally begin in May or June in lower Niger below its confluence with the Benue earlier than in the mid part of Niger and a low-water period, which is mostly shorter with less than a month, due to the earlier onset of the rains South ward (Ahmed, 2001; Amanambu et al., 2019).

1.7.2.3 Spatial extent of the Rivers Niger and Kaduna catchments

Rivers Niger is the longest river in Nigeria; it covers an area of about 4,180 km (2600 miles). The river rises on the Fouta Djallon Plateau, South West (SW) Guinea, flowing North East (NE) through Guinea into Mali and Niger before entering Nigeria through Lokoja, where it forms part of its borders with Benin before emptying into Gulf of Guinea within the Atlantic Ocean via the Niger Delta. River Niger has been classified as the third longest in Africa continent and ranked 11th longest river in the World. This river gets its source from the Guinea Highlands, while its main tributaries are from Kaduna River, Sokoto River, Bani River and Benue River. The volume of the river does not remain the same throughout the year as it fluctuates from time to time. Other factors such as increased water abstraction for irrigation farming and seasonal fluctuation (Climate change) have largely affected the volume and flow of the Niger River (Ahmed, 2001; Ifejika et al., 2013; Abrate et al., 2013).

River Kaduna, a tributary of the Niger River rises on the Jos Plateau 18 miles (29 km) southwest of Jos town near Vom and flows in a northwesterly direction to a bend 22 miles (35 km) northeast of Kaduna town. It then adopts a southwesterly and southerly course before completing it 340-mile (550-kilometre) flow to the Niger at Muregi (Ifejika et al., 2013).

1.7.2.4 Flow pattern of Niger River and Kaduna catchments

River Niger flows in an unusual direction; its flow is unusual because its source is precisely 240 km which is equal to 150 miles from the Atlantic Ocean. Niger instead of flowing directly into the nearby Atlantic Ocean, it rather flows straight ward Far from the sea into the Sahara, then takes sharp to the right closed to the ancient city of Timbuktu and move directly southeast to the Gulf of Guinea. The unusual flow is because of the two ancient rivers that join the Niger River together (Ahmed, 2001; Ifejika et al., 2013; Idowu and Zhou, 2019). The Kaduna River is a tributary of the Niger River, which flows for  550  kilometres  (340 mi)  through Nigeria. It  starts  in Plateau  State on  the Jos Plateau 29 kilometres (18 mi) southwest of Jos town, flows through its namesake Kaduna State and through its capital Kaduna, and meets the Niger River in Niger State at Muregi. Most of its course passes through savanna woodland, but its lower section has cut several gorges above its entrance into the extensive Niger floodplains (Idowu and Zhou, 2019).

1.7.2.5 Economic importance of Rivers Niger and Kaduna catchments

Rivers Niger and its catchments provide water for irrigation farming during the arid season, particularly for inhabitants living close the river; the inhabitant of Niger State mostly depend on this river to irrigate their crops. The point where the river (River Niger and Benue) meets to form a confluence provides the needed volume and speed to power the energy for the generation of hydroelectric power stations. This energy serves Nigeria and other some neighbouring countries, hence, contributing to the economic development of Nigeria. River Niger and its catchments offers sources of livelihood to the Niger State through fishing and selling of surplus fish to the market. Niger River and its catchments serve as a home to different water creatures such as the African lion, African manatee (sea cow), catfish, carp, Nile perch, hippopotamuses, and crocodiles among other animals.

Large-scale farming takes place at the bank of the River Niger and its catchments; most of these crops are sold within the country, while the majority of these are exported to other countries (Ahmed, 2001; Ifejika et al., 2013; Meseko et al., 2018). The river helps provide job opportunity for sailor and local fishers, as the waters are deep enough for different species of fish. The river serves as the main water source for domestics and industrial activities in Niger State, mostly after it has been purified. River Niger and its catchments have a significant length and depth, which makes it possible for navigation; they are often used for commercial shipping for transporting heavy goods to Onitsha from the Atlantic Ocean all over the year. The river has enough deposits of sand, both the Sand, mud is usually removed from the bottom of the river for construction of roads and houses. Irrigation farming taking place in Bamako, the capital city of Mali on the bank of the Niger River (Ahmed, 2001; Ifejika et al., 2013: Meseko et al., 2018).

River Kaduna is used for fishing and for transport of local produce. Gbari (Gwari) people have utilized the Kaduna’s upper floodplains for swamp rice cultivation, and in the southern plains, in Nupe tribal territory, rice and sugarcane production has become a major economic activity. Near Bida, the Edozhigi and Badeggi natural irrigation projects are major rice-growing ventures.

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