Water quality and dissolved inorganic fluxes of N, P, SO4, and K of a small catchment river in the Southwestern Coast of India

Abstract

The southwestern coast of India is drained by many small rivers with lengths less than 250 km and catchment areas less than 6,500 km(2). These rivers are perennial and are also the major drinking water sources in the region. But, the fast pace of urbanization, industrialization, fertilizer intensive agricultural activities and rise in pilgrim tourism in the past four to five decades have imposed marked changes in water quality and solute fluxes of many of these rivers. The problems have aggravated further due to leaching of ionic constituents from the organic-rich (peaty) impervious sub-surface layers that are exposed due to channel incision resulting from indiscriminate instream mining for construction-grade sand and gravel. In this context, an attempt has been made here to evaluate the water quality and the net nutrient flux of one of the important rivers in the southwestern coast of India, the Manimala river which has a length of about 90 km and catchment area of 847 km(2). The river exhibits seasonal variation in most of the water quality parameters (pH, electrical conductivity, dissolved oxygen, total dissolved solids, Ca, Mg, Na, K, Fe, HCO(3), NO(2)-N, NO(3)-N, P[Formula: see text], P[Formula: see text], chloride, SO(4), and SiO(2)). Except for NO(3)-N and SiO(2), all the other parameters are generally enriched in non-monsoon (December-May) samples than that of monsoon (June-November). The flux estimation reveals that the Manimala river transports an amount of 2,308 t y(-1) of dissolved inorganic nitrogen, 87 t y(-1) dissolved inorganic phosphorus, and 9246 t y(-1) of SO(4), and 1984 t y(-1) K into the receiving coastal waters. These together constitute about 23% of the total dissolved fluxes transported by the Manimala river. Based on the study, a set of mitigation measures are also suggested to improve the overall water quality of small catchment rivers of the densely populated tropics in general and the south western coast in particular.

Evaluating the applicability of MESS (matrix exponential spatial specification) model to assess water quality using GIS technique in agricultural mountain catchment (Western Carpathian)

“…The obtained research results indicate that the land use shapes the structure of waterside water quality, as well as affects the condition of watercourses, especially in terms of their content of nitrates, phosphates and sulfates (Akan et al 2012 ; Wallender and Tanji 2012 ) and sodium, potassium, calcium, sodium and magnesium cations (Purandara et al 2012 ). The most Ca, Mg, Na, K, Fe, N-NO 2 , Cl − and SO 4 were found in waters flowing through a field complex in the spring (Padmalal et al 2012 ). According to Bu et al ( 2017 ), this process is associated with greater biological sorption of minerals by plants grown in summer, and smaller by plants in the spring.…”

Spatiotemporal variability in groundwater chemistry of a mountainous catchment with complex geologic and climate gradients in south west India

“…Over-dependence on the groundwater resources and human interventions in the catchments has often led to large-scale decline in the quantity and quality of the groundwater resources even in mountainous catchments (Guo and Wang, 2005;Peisert and Sternfeld, 2005;Vaux, 2007;Sadoff and Muller, 2009;Padmalal et al,2011;Vaux, 2011;Hallouche et al, 2017;Kaushal et al,2017). Social and economic activities of the catchments are mostly dependent on the availability and quality of groundwater for various purposes (Hosseinifard and Aminiyan, 2015;Elgallal et al, 2016;Chandran et al, 2017;Wu et al, 2017;Jampani et al, 2018 andPincetti-Zúniga et al,2020).…”

Characterization of the microbial community in a lotic environment to assess the effect of pollution on nitrifying and potentially pathogenic bacteria

“…In the past, these criteria included only physicochemical parameters (Murray et al, 2001). Indeed, several studies have shown that urbanisation increases the concentration of some nutrients, such as nitrogen, ammonia, nitrate, and phosphorus, decrease the concentration of oxygen and is responsible for pH changes in rivers and streams (Hoare, 1984;Meybeck, 1998;Wernick et al, 1998;Martinelli et al, 2010;Cumar and Nagaraja, 2011;Padmalal et al, 2012). However, the analysis of the chemical and physical characteristics of an ecosystem becomes limited when the objective is the understanding of its complexity as the biological components should also be taken into account.…”

“…Since it has been shown that urbanisation is related to the incresase in nitrogen, ammonium and nitrate levels (Hoare, 1984;Meybeck, 1998;Wernick et al, 1998;Martinelli et al, 2010;Cumar and Nagaraja, 2011;Padmalal et al, 2012), one can hypothesise that it could influence the density and diversity of nitrifying and denitrifying microbes in impacted ecosystems. Considering the global nitrogen cycle, nitrification and denitrification are important steps.…”