Effects of COVID-19 Lockdown And Unlock On Health of Tropical Large River With Associated Human Health Risk

42 From the last month of 2020, sudden outbreak of novel corona virus caused socio-economic lockdown 43 in many countries. Many studies proved that temporary shutdown of economic sectors helped to 44 recover river water quality. Perhaps, for the first time, this present study is conducted in an 45 industrially and agriculturally influenced catchment of river Damodar, India. This research was fixed 46 some relevant objectives like (i) to evaluate the changes of heavy metals (Zn, Cd, Pb, Ni, Cr and Fe) 47 and microbial contamination (TVC, TC and FC) of river water (ii) to identify the magnitude of human 48 health hazard during lockdown compared to pre lockdown and unlock phase. Total 33 water samples 49 were collected in three periods. During lockdown, TVC, TC and FC showed the gradual decreasing 50 trend in this stretch. All samples exceed the concentration of microbes compared to recommended 51 standard in three periods. Among all heavy metals, Zinc, iron, chromium found their abandoned 52 presence in the river water. Heavy Metal Pollution Index (HPI) showed 100% sample water of highly 53 polluted (HPI > 150) type for drinking and other purpose. During lockdown, HPI showed around 54 54.54% sample changed to lower pollution and 45.45% changed to medium pollution level. During 55 unlock phase, 45.45% samples again changed to high pollution. Pearson’s correlation coefficient and 56 hierarchical cluster analysis indicated strong relation among heavy metals with fecal coliform in this 57 river. This suggests high possibilities of common source of contamination (wastes of iron and steel 58 plant, chemical plant, cement factories, agricultural runoff, municipal sewages etc) in river bed. No 59 carcinogenic Hazard Index (HI) values of ingestion by children indicated higher potentiality to health 60 risk (HI > 1) in all samples of three periods and during lockdown, 36.36% samples showed no 61 possible health risk for adults (HI < 1). HI of dermal contact showed no possible health risk for 62 children and adults in three periods. This assessment strongly recommended scientific and cheep 63 management techniques to control water pollution and related health hazard in the study area. this study performed on the basis of microbial FC), heavy metals Ni, Fe) and related of three different lockdown), during lockdown and new normal (unlock) phase. The study showed that TVC, their standard limit of concentration in three There was noticeable decrease in microbial load in water during lockdown. Mean concentration of heavy


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It has now become a great environmental issue that deterioration of surface water quality is  From the past few decades, aquatic environment is being faced by hazardous heavy metals.  (Tumuklu et al., 2007). Higher intake of iron with drinking water 89 may lead to gastrointestinal disorder (Rezaei et al., 2017). Excess concentration of nickel in 90 drinking water damages lungs and nasal organ, and it can also reduce body weight, heart 91 affectivity etc (USEPA 1995). Higher intake of lead with drinking water rises blood pressure,   were no published evidence of water quality changes among pre lockdown, during lockdown 147 and unlock period of river Damodar based on heavy metals and microbial load with using 148 advanced GIS techniques. Therefore, the main objectives of this study were (i) to evaluate the 149 changes of heavy metals and microbial load of river water in three period i.e., pre lockdown, 150 during lockdown and unlock (ii) to identify major sources of contaminants and their 151 interrelation using correlation and multivariate analysis and (iii) to assess potential health 152 hazard (non-carcinogenic) of children and adult residence of the catchment area.      (Table 1). 'K' indicates proportional 222 constant value i.e., 1.

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In the second step, quality rating (Qi) value has been obtained by using formula below: Where, Mi refers the measured value of each metal in water samples. Ii and Si denote the 226 ideal value and standard value of each metal respectively. In this study, Mi and Si of heavy 227 metals were taken from BIS guidelines (Table 1).

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At last, calculation of HPI was conducted as follow: were assessed for no carcinogenic type of diseases for children and adults in the study area.

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Health risk of heavy metal ingestion can be analysed by measuring chronic daily dose intake 242 (CDI) using following formula suggested by USEPA (2011).
Where, CDIi is chronic daily dose intake of particular heavy metal (µg/kg/day), Cw is days for children and 10,950 days for adults) for non-carcinogenic health risk.

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CDI of dermal adsorption was analysed by the prescribed method of USEPA as follow, Where, CDId is chronic daily dose intake by dermal contact by heavy metals ((µg/kg/day). SA 253 denotes available area of skin contact (cm 2) . Kp designates permeability coefficient 254 (cm/hour). ET denotes exposure time (h/day), CF is the conversion factor of unit (L/cm 3 ).

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Hazard Quotient (HQ) of each heavy metal was estimated by the ratio of CDI and reference 256 dose of oral intake (RfD) using following formula.
RfD (µg/kg/day) of each metal was obtained from USEPA guidelines of drinking water 259 quality (Table 1).

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Potential to health risk by all heavy metals of non-carcinogenic type was computed by using 261 following formula.

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In pre lockdown, during lockdown and unlock period, dendogram of cluster analysis showed 331 that there were three cluster of microbial and heavy metal parameters (Fig.3 a, b, c)

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In the study stretch of river Damodar, HPI of pre lockdown showed that around 100% water 341 samples (n = 11) were highly polluted by heavy metal contamination ( 346 This outcome exposed again increase of contamination of heavy metals and their pollution in 347 river water. Spatial mapping showed that the lower course of river water was more polluted 348 by heavy metals in three periods (Fig 4).  In pre lockdown period, mean HQ value of six heavy metal ingestion by children was found 357 as an order of Zn > Cd, Cr > Pb > Ni > Fe by their mean value ( Total HI value of dermal adsorption by children in pre lockdown was obtained its ranges 385 4.58E-02 to 7.07E-02 with 6.00E-02 mean value (Fig. 5b) for adults and children (Table 4).

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There is enormous possibility to do further study in these changing circumstances and 477 simultaneously it is highly required to find out the solutions because this river contributes 478 multidimensional ecosystem services to millions of people in India. This field based scientific 479 study will assist to policy makers for sustainable management of river health.

Competing interests 505
The authors declare that they have no competing interests. 506

Ethics approval and consent to participate 507
Not applicable 508

Consent for publication 509
Not applicable 510

Data availability 511
The datasets used and analyzed during the current study are available from the corresponding author 512 on reasonable request.