International Journal of Scientific and Research Publications, Volume 6, Issue 6, June 2016 282 ISSN 2250-3153 Assessment on factors controlling nutrient dynamics in a small tropical river using multivariate analysis Prince George and Sabu Joseph Dept. of Environmental Sciences, University of Kerala, Thiruvananthapuram Abstract- Water samples (N= 96) were collected from Meenachil number of random processes, including rainfall, runoff, river for 16 locations (S1-S16) in pre monsoon (PRM), monsoon anthropogenic activities, geology etc. Water quality can be (MON) and post monsoon (POM) seasons during 2013 and 2014. affected when watersheds are modified by alterations in landuse The nutrients like NO3, PO4 (<1 mg/L) and SiO2 (<4 mg/L) are pattern, sediment balance, or fertilizer use from industrialization, generally low in the river, and increases from upstream to urbanization, or conversion of forests and grasslands to downstream. The cations of abundance include Na> Ca> K> agriculture and silviculture [3]. Natural factors like geology, Mg> Fe for PRM, Ca> Na> Mg> K> Fe for MON and Na> Ca> climate, hydrology and vegetation are usually first order controls Mg> K> Fe for POM. Anion abundance include of the amount and composition of dissolved and particulate Cl>HCO3>SO4>SiO2>NO3>NO2>PO4 during PRM, HCO3> Cl> substances transported by rivers. Now-a-days, human-induced SO4> SiO2> NO3> PO4> NO2 during MON and Cl> HCO3> environmental changes often go far beyond natural variations and SO4> NO3> SiO2> NO2> PO4 during POM. The factor analysis therefore may lead to drastic change in the river input to estuaries result illustrate F1 loading (TEMP, TH, SAL, Mg, Ca, SO4, Na, and affect coastal ecosystems [4]. Increased nutrient input into K, Cl and HCO3) of 69.85 % during PRM clearly indicating the the riverine system emphasizes the imbalances and alterations in role of tropical weathering process in the river system. From the terrestrial sources. Thus the quantity and quality of nutrient input F1 loading during MON, it is interpreted that positive loading of to the rivers needs to be monitored to cope with the existing and NO2, PO4, Na and K indicate role of agricultural runoff in future climatic and environmental changes [5]. determining the water quality of river system. During POM, F1 The water quality assessment, however, does not focus on loading for TH, SAL, PO4, Mg, Ca, SO4, Na, K and Cl the instantaneous concentration as it is seldom that the accounting 67.89 % variance depicts influence of agricultural as instantaneous concentration has an impact on the water user. well as anthropogenic activity on the river system. Cluster Rather the overall difference in the magnitude of the analysis reveals that stations in the highland and a part of concentration and range of concentration over a period of time midland (S1-S10) is comparatively less polluted. During PRM, must be used as a measurement of the water quality status [6]. river mouth station S16 alone forms a separate cluster indicating Due to spatial and temporal variations in water chemistry a dominance of saline water ingress in that station. While in POM stringent and scientific mode of continuous water quality the effect of liming of agricultural land in this watershed also has monitoring pattern is necessary for surface waters especially for much influence in controlling the river water chemistry in the rivers. Thus, monitoring programs including frequent water lowland stations especially S14, S15 and S16. samplings from specific sites and determination of its quality is of vital value. Index Terms- River nutrients, Tropical river, Pollution identification, Multivariate analysis Study area The Meenachil river (Order= 7th; Length= 78 km; Area= 1272 km2), one of the important rivers in Central Kerala (Fig.1), I. INTRODUCTION is formed by several streams originating from the Western Ghats ivers constitute to the main water resources in inland areas at Araikunnumudi (elevation=1097m above msl) and flows in the R for drinking, irrigation and industrial purposes; thus, it is a E-W direction and finally debouch into the Vembanad lake (a prerequisite for effective and efficient water management to have Ramsar site). The entire river basin area geographically lies between N latitude 9025’ to 9055’ and E longitude 76030’ to reliable information of water quality [1]. Livelihoods such as 0 agriculture, fishing and animal husbandry are affected by poor 77 00’. Major part (41 km; 53%) of this river runs through water quality. Biodiversity, especially of freshwater ecosystems midland terrain, 21 km (27%) through the highland and the rest is under threat due to water pollution [2]. The water quality of a (16 km; 20%) is seen to flow through the low land terrain. The natural stream is determined by the concentration of different river has 47 sub-watersheds and 114 micro-watersheds [7,8]. It chemical variables of the water body. The change in the has 38 tributaries including major and minor ones. concentration of these different variables is the result of a www.ijsrp.org International Journal of Scientific and Research Publications, Volume 6, Issue 6, June 2016 283 ISSN 2250-3153 Figure 1. Location map of study area The major tributaries are Kadapuzha, Kalathukadavu, period the mean annual temperature of the area is 32.50C, Kurisumalai, Trikkoil, Punjar, Meenadom [9]. The river exhibits experiencing average annual rainfall of 3030 mm, while mean a dendritic drainage pattern and splits into a number of humidity is 88.6 percent. The basin experiences both south-west distributaries in the lowlands and finally merges with the and north-east monsoons. The south-west monsoon sets during Vembanad Lake at Kavanattinkara [10]. June and lasts till August. The north-east monsoon, which is The basin primarily comprises of Precambrian metamorphic rock uncertain strikes in October and continues till the end of system. The major soil type prevalent in the area is well drained November. lateritic soils, while main rock types of the area belong to Charnockite/charnakite gneiss, Biotite gneiss (migmatite), SAMPLING SCHEME AND METHODOLOGY cordierite gneiss, magnetite quartzite and pyroxene granulite. River water samples (total no.= 96) were collected in Quaternary formations of fluvial deposit, fluvio marine and paleo Meenachil river from upstream to downstream for 16 locations marine deposits were found in lower reaches of river [11]. (S1-S16) The water samples were collected for pre monsoon The Meenachil river basin falls within the realm of tropical (PRM), monsoon (MON) and post monsoon (POM) seasons humid climate and high variations in relief from the west coast to during 2013 and 2014. The portrait of sampling locations was the hilly region of the Western Ghats in the east and proximity to given in table 1 and figure 2. the sea influence the climatic parameters. During 2010 – 2014 www.ijsrp.org International Journal of Scientific and Research Publications, Volume 6, Issue 6, June 2016 284 ISSN 2250-3153 Figure 2. Portrait of Sampling locations titrating against thiosulphate using starch as indicator, while The samples were collected in clean polyethylene bottles BOD is measured after incubating it for 5 days at 200C. All kept under dark or below ambient temperature and were analysed spectrophotometric analysis were done using Systronics UV- using standard procedures [12,13]. The parameters identified VIS, 118, spectrophotometer while Na and K were determined include Temperature, pH (Systronics pH meter, 361), TDS, using Flame Photometer (Elico CL 361) after conducting Conductivity (Systronics Conductivity-TDS meter, 308), Total standard calibration. Chloride concentrations were estimated by Hardness (TH),Total Solids (TS), Salinity, HCO3, Fe, PO4, Si, employing argentometric titration using standard silver nitrate DO, BOD, NO2, NO3, Mg, Ca, SO4 and Cl. DO was estimated by solution having potassium chromate as indicator. Winkler’s Iodometric method using MnSO4 and alkai KI and Table 1. Description of sampling stations Station No. Stations Lat. (N) Long. (E) Location remarks S1 Adivaram 9039’44.8” 76052’3.8” Forest and plantation S2 Perumkulam 9040’17.9” 76050’33.7” Forest and plantation S3 Tikkoi 9041’57.8” 76048’45.1” Plantation and Mixed vegetation S4 Punjar 9040’13.8” 76048’2.1” Plantation and Mixed vegetation S5 Erattupetta 9041’9.8” 76046’36.4” Plantation and Mixed vegetation S6 Baranamghanam 9041’53.2” 76043’52.9” Plantation and Mixed vegetation S7 Pala 9042’32.5” 76040’56.3” Plantation and Mixed vegetation S8 Kadapattoor 9042’19.7” 76040’27.6” Plantation and Mixed vegetation S9 Cherpungal 9041’8.6” 76038’3.2” Plantation and Mixed vegetation S10 Kidangoor 9040’22.4” 76036’12.3” Plantation and Mixed vegetation S11 Pattarmadom 9038’56.1” 76035’12.5” Plantation and Mixed vegetation S12 Perror 9037’45.8” 76034’1.5” Plantation and Mixed vegetation Kottayam Railway Plantation,Mixed vegetation and S13 9035’44.2” 76031’47.3” Bridge minor industrial area S14 Chungam 9035’55.5” 76031’6.6” Paddy and Mixed vegetation S15 Illickal 9035’13.5” 76029’32.2” Paddy and Mixed vegetation S16 Kavanattinkara 9037’36.9” 76025’52.9” Paddy, river lake interface area www.ijsrp.org International Journal of Scientific and Research Publications, Volume 6, Issue 6, June 2016 285 ISSN 2250-3153 Total Solids, TS II. RESULTS AND DISCUSSION During PRM, TS ranged from 0.05 to 0.41 mg/L having a a. Spatio-temporal nutrient variability mean value of 0.13. The maximum concentration was observed The water quality analysis of river water conducted for at S16 (Kavanattinkkara). However, during MON, TS has mean PRM, MON and POM of 2013 and 2014. For the convenience of value of 0.16, with maximum concentration of 0.41 mg/L at S16 study, the season wise averaged data for 2013 and 2014 are station (Kavanattinkkara). During POM, TS ranged from 0.03 to presented in Figure 3-4 .