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Runoff quality and pollution loadings from a tropical urban catchment

Yusop Z, Tan LW, Ujang Z, Mohamed M, Nasir KA

Water Sci Technol, 2005;52(9):125-32.
PMID: 16445181

Runoff quality draining from 17.14 km2 urban catchment in Johor Bahru, Malaysia, was analysed. The land-use consists of residential (30.3%), agricultural (27.3%), open space (27.9%), industrial (8.1%) and commercial (6.4%) areas. Three storm events were sampled in detail. These storms produced stormflow between 0.84 mm and 27.82 mm, and peakflow from 2.19 m3/s to 42.36 m3/s. Water quality showed marked variation during storms especially for TSS, BOD and COD with maximum concentrations of 778 mg/l, 135 mg/l and 358 mg/l, respectively. Concentrations of TOC, DOC, NH3-N, Fe and level of colour were also high. In general, the river quality is badly polluted and falls in Class V based on the Malaysian Interim National Water Quality Standards. Event Mean Concentrations (EMC) for various parameters varied considerably between storms. The largest storm produced higher EMC for TSS, NO3-N and SS whereas the smaller storms tend to register higher EMC for BOD, COD, NH3-N, TOC, Ca, K, Mg, Fe and Zn. Such variations could be explained in terms of pollutant availability and the effects of flushing and dilution. Based on a three-month average recurrence interval (ARI) of rainfall, the estimated event loadings (ton/ha) of TSS, BOD, COD, TOC, NH3-N and NO3-N were 0.055, 0.016, 0.012, 0.039, 0.010, 0.0007 and 0.0002, respectively. Heavy metals present in trace quantities. Storms with 3 months ARI could capture about 70% of the total annual loads of major pollutants.

Matched MeSH terms: Rain
Fulltext Temporal changes of aedes and armigeres populations in suburban and forested areas in Malaysia

Nurin-Zulkifli IM, Chen CD, Wan-Norafikah O, Lee HL, Faezah K, Izzul AA, et al.

Southeast Asian J. Trop. Med. Public Health, 2015 Jul;46(4):574-85.
PMID: 26867376

Surveillance of mosquitoes and their distribution in association with rainfall, relative humidity, and temperature were conducted in selected suburban and forested areas, namely, Sungai Penchala (Kuala Lumpur) and Taman Alam (Selangor) for 12 months. Armigeres kesseli was the most abundant species in Sungai Penchala while Aedes butleri was the most dominant species in Taman Alam. A positive correlation between mosquito distribution and rainfall was observed in selected mosquito species in Sungai Penchala (Armigeres kesseli, r = 0.75; Armigeres subalbatus, r = 0.62; and Aedes albopictus, r = 0.65) and Taman Alam (Armigeres sp, r = 0.59; Ae. butleri, r = 0.85; and Ae. albopictus, r = 0.62). However, no significant cor- relation was found either between selected mosquito species in both study areas and relative humidity or temperature. Results obtained suggested that vector control programs to be conducted based on temporal distribution of vectors in order to achieve beneficial outcomes with effective costing.

Matched MeSH terms: Rain
The role of extreme events in the impacts of selective tropical forestry on erosion during harvesting and recovery phases at Danum Valley, Sabah

Douglas I, Bidin K, Balamurugan G, Chappell NA, Walsh RP, Greer T, et al.

Philos Trans R Soc Lond B Biol Sci, 1999 Nov 29;354(1391):1749-61.
PMID: 11605619

Ten years' hydrological investigations at Danum have provided strong evidence of the effects of extremes of drought, as in the April 1992 El Niño southern oscillation event, and flood, as in January 1996. The 1.5 km2 undisturbed forest control catchment experienced a complete drying out of the stream for the whole 1.5 km of defined channel above the gauging station in 1992, but concentrated surface flow along every declivity from within a few metres of the catchment divide after the exceptional rains of 19 January 1996. Under these natural conditions, erosion is episodic. Sediment is discharged in pulses caused by storm events, collapse of debris dams and occasional landslips. Disturbance by logging accentuates this irregular regime. In the first few months following disturbance, a wave of sediment is moved by each storm, but over subsequent years, rare events scour sediment from bare areas, gullies and channel deposits. The spatial distribution of sediment sources changes with time after logging, as bare areas on slopes are revegetated and small gullies are filled with debris. Extreme storm events, as in January 1996, cause logging roads to collapse, with landslides leading to surges of sediment into channels, reactivating the pulsed sediment delivery by every storm that happened immediately after logging. These effects are not dampened out with increasing catchment scale. Even the 721 km2 Sungai Segama has a sediment yield regime dominated by extreme events, the sediment yield in that single day on 19 January 1996 exceeding the annual sediment load in several previous years. In a large disturbed catchment, such road failures and logging-activity-induced mass movements increase the mud and silt in floodwaters affecting settlements downstream. Management systems require long-term sediment reduction strategies. This implies careful road design and good water movement regulation and erosion control throughout the logging process.

Matched MeSH terms: Rain
Seasonality of Anopheles aconitus mosquitoes, a secondary vector of malaria, in an endemic village near the Malaysia-Thailand border

Rahman WA, Abu Hassan A, Adanan CR

Acta Trop, 1993 Dec;55(4):263-5.
PMID: 8147283
Matched MeSH terms: Rain
Human rotavirus infection in Malaysia. III. A one year survey on the prevalence of rotavirus enteritis in children

Yap KL, Sabil D, Muthu PA

Southeast Asian J. Trop. Med. Public Health, 1983 Dec;14(4):467-9.
PMID: 6673122

The prevalence of human rotavirus enteritis in children admitted to the gastroenteritis ward of the Kuala Lumpur General Hospital was studied in 1982. Human rotavirus in the stool of the patients was detected by enzyme-linked immunosorbent assay. The survey showed that rotavirus enteritis in children were observed throughout the year, with two broad peaks of rotavirus infection occurring around March and September. The lowest incidence was recorded in July, however, no prolonged period of low prevalence of rotavirus enteritis was observed. The average prevalence for the whole of 1982 was 40% of the total diarrhoeal cases. No significant relationship was noted between the prevalence of the disease and rainfall.

Matched MeSH terms: Rain
Seasonal population patterns of Spalangia endius Walker (Hymenoptera: Chalcidoidea) at a refuse dumping ground in Malaysia

Sulaiman S, Omar B, Omar S, Jeffery J, Ghauth I, Busparani V

J Med Entomol, 1991 Nov;28(6):757-9.
PMID: 1770508

A study on population patterns of the parasitoid Spalangia endius Walker at a dumping ground near Kuala Lumpur city showed that the percentage of S. endius adult emergence varied seasonally. During the relatively heavy rainfall months of August and November 1988, and January, March, and April 1989, the population of S. endius adult emergence were low (0-14.2%) compared to the less rainy months of July, September, and December 1988, and May 1989 (29.3-39.6%). This information could be useful in formulating strategies to reduce house fly population at the refuse dumping ground through integrated pest management programs.

Matched MeSH terms: Rain
Field and laboratory observations on Coquillettidia crassipes in relation to transmission of Brugia malayi in Peninsular Malaysia

Chiang GL, Samarawickrema WA, Mak JW, Cheong WH, Sulaiman I, Yap HH

Ann Trop Med Parasitol, 1986 Feb;80(1):117-21.
PMID: 2873797

Field observations were made on Coquillettidia crassipes during a study of Mansonia in a swamp forest ecotype in Tanjong Karang. There was an increase in abundance in July consistent with the increase in abundance of Mansonia and an increase in rainfall. The biting cycle showed a dramatic early peak during the period 1900-2000 hours. The probability of daily survival through one day for the first three gonotrophic cycles was 0.770, 0.722 and 0.759. Two of the 54 Cq. crassipes dissected were infective, with two and 25 L3 larvae of Brugia. Both subperiodic B. malayi and B. pahangi developed into L3 larvae in laboratory bred Cq. crassipes. The index of experimental infection was higher for B. pahangi. Mansonia bonneae and Ma. uniformis showed higher indices of experimental infection than Cq. crassipes for subperiodic B. malayi. It is concluded that in an endemic area with a high density of Cq. crassipes it could act as a secondary vector of Brugian filariasis.

Matched MeSH terms: Rain
Fulltext Coral mass spawning predicted by rapid seasonal rise in ocean temperature

Keith SA, Maynard JA, Edwards AJ, Guest JR, Bauman AG, van Hooidonk R, et al.

Proc Biol Sci, 2016 05 11;283(1830).
PMID: 27170709 DOI: 10.1098/rspb.2016.0011

Coral spawning times have been linked to multiple environmental factors; however, to what extent these factors act as generalized cues across multiple species and large spatial scales is unknown. We used a unique dataset of coral spawning from 34 reefs in the Indian and Pacific Oceans to test if month of spawning and peak spawning month in assemblages of Acropora spp. can be predicted by sea surface temperature (SST), photosynthetically available radiation, wind speed, current speed, rainfall or sunset time. Contrary to the classic view that high mean SST initiates coral spawning, we found rapid increases in SST to be the best predictor in both cases (month of spawning: R(2) = 0.73, peak: R(2) = 0.62). Our findings suggest that a rapid increase in SST provides the dominant proximate cue for coral mass spawning over large geographical scales. We hypothesize that coral spawning is ultimately timed to ensure optimal fertilization success.

Matched MeSH terms: Rain
Fulltext Effects of saline irrigation water on morphological characteristics of banana (Musa spp.)

Al Harthy, K. M., Siti Aishah, H., Yahya, A., Roslan, I., Al Yahyai, R.

International Food Research Journal, 2018;25(102):195-200.
MyJurnal

Banana is one of the most important food crops after rice, wheat and corn around the world. It is susceptible to a wide spectrum of non-infectious problems such as abiotic stresses resulting in restricting growth and production. Studies were conducted to determine the effects of four salinity levels (0.17 (control), 3.0, 6.0, and 9.0 dS m-1) on morphological characteristics of four banana cultivars at vegetative growth stage. Banana cultivars from the Cavendish group (Williams, Malindi) and plantains group (FHIA18 and Diwan) were grown in 61 x 76 cm polyethylene bags filled with soil mixture comprising of top soil, sand and peat moss (3:1:2 v/v), with pH ranging from 6 - 6.5 and EC 0.02 mScm-1. The experiment was carried out under a rain-shelter in split-plot design with three replicates. Plants were irrigated manually. Data were collected at 3, 6 and 9 months after transplanting. The results revealed that, the number of leaves, stem height, stem girth and total leaf area were significantly affected by salinity, variety and plant age. Significant interaction was also found between salinity and variety, salinity and plant age, as well as variety and plant age. The morphological characteristics of banana were negatively affected by higher salinity levels (6.0 and 9.0 dS m-1). Under similar salinity level, cultivar Malindi had higher number of leaves, stem height, stem girth and total leaf area as compared to cultivar Williams. Among plantains banana, cultivar FHIA18 was more tolerance to high salinity levels than Diwan cultivar, while Malindi from Cavendish group shows high salt tolerant than Williams. Therefore cultivars Malindi and FHIA18 could be grown in arid and semiarid environment depend on their tolerance to high salinity level above 1.0 dS m-1.

Matched MeSH terms: Rain
Fulltext Devastating urban flooding and dengue outbreak during the COVID-19 pandemic in Pakistan

Junaid Tahir M, Rizwan Siddiqi A, Ullah I, Ahmed A, Dujaili J, Saqlain M

Med J Islam Repub Iran, 2020;34:169.
PMID: 33816368 DOI: 10.47176/mjiri.34.169

Pakistan has recently been overwhelmed by extreme torrential rains, with its most populous city of Karachi experiencing its worst floods in almost a century. Poor flood control and water disposal facilities have led to an immense risk of another dengue outbreak, with multiple cases being reported recently. The enormous accumulation of stagnant water in urban areas is a major source of mosquito breeding and transmission. Historical data has shown the correlation between the number of dengue cases and average rainfall in the region. The monsoon rains have pounded at a time where health authorities are battling to contain the Coronavirus (COVID-19) pandemic. There is a need to implement centralized dengue control strategies to undertake large scale water drainage, sanitation, and disinfection drives in disaster-stricken areas alongside public health awareness programs to combat the after-effects of this natural calamity.

Matched MeSH terms: Drainage; Rain
Fulltext Small temperature variations are a key regulator of reproductive growth and assimilate storage in oil palm (Elaeis guineensis)

Tani N, Abdul Hamid ZA, Joseph N, Sulaiman O, Hashim R, Arai T, et al.

Sci Rep, 2020 01 20;10(1):650.
PMID: 31959766 DOI: 10.1038/s41598-019-57170-8

Oil palm is an important crop for global vegetable oil production, and is widely grown in the humid tropical regions of Southeast Asia. Projected future climate change may well threaten palm oil production. However, oil palm plantations currently produce large amounts of unutilised biological waste. Oil palm stems - which comprise two-thirds of the waste - are especially relevant because they can contain high levels of non-structural carbohydrates (NSC) that can serve as feedstock for biorefineries. The NSC in stem are also considered a potent buffer to source-sink imbalances. In the present study, we monitored stem NSC levels and female reproductive growth. We then applied convergent cross mapping (CCM) to assess the causal relationship between the time-series. Mutual causal relationships between female reproductive growth and the stem NSC were detected, with the exception of a relationship between female reproductive organ growth and starch levels. The NSC levels were also influenced by long-term cumulative temperature, with the relationship showing a seven-month time lag. The dynamic between NSC levels and long-term cumulative rainfall showed a shorter time lag. The lower temperatures and higher cumulative rainfall observed from October to December identify this as a period with maximum stem NSC stocks.

Matched MeSH terms: Rain
Fulltext THE EFFECT OF LOW pH LEVEL ON ZEBRAFISH (Danio rerio) REPRODUCTIVE PERFORMANCE

Ikram Ismail, Siti-Ariza Aripin

UMT Journal of Undergraduate Research, 2020;2(1):15-20.
MyJurnal

Danio rerio or commonly known as zebrafish are a very popular fish among scientists and also a well-known vertebrate model species widely used in research. Zebrafish, are also a popular species among aquarists and have been put in aquariums all around the world as ornamental fish. The acid rain phenomenon has lowered the pH level of the wild habitat of zebrafish by shifting it to a more acidic pH level. This study was carried out to observe the effect of low pH level on the reproductive performance of zebrafish. The zebrafish were quarantined for a week to make sure they were healthy to be used in the experiment. The zebrafish were reared continuously for 14 days in three different pH treatments T1 (pH 2-4), T2 (pH 4-6), T3 (pH 6-8)). T3 (pH 6-8) was used as the control treatment. Hydrochloric acid (HCl) was used to control the pH level of treatments T1 (pH 2-4), T2 (pH 4-6), T3 (pH 6-8) with three replicates of each treatment. The male chasing female frequency was significant (p: 0.0001) and the data showed the highest frequency (2568.000±140.6272) at treatment 3 (pH 6-8). For the spawning frequency of zebrafish, treatment 3 (pH 6-8) showed the highest value (4.000±0.5774) followed by treatment 2 and treatment 1 and the data was significant (p: 0.0004). The fertilisation rate of the zebrafish was significant (p: 0.0001) and the highest was shown at T2 (pH 4-6) with 89.8018±0.3782, followed by T3 and treatment T1. For the hatching rate of the zebrafish, the data collected were significant (p: 0.0002) and the highest value of 2.9350±0.4070 was shown at T3 (pH 6-8), followed by T2 (pH 4-6) and T1 (pH 2-4). The overall result showed that pH 2-4 had the worst effect on the reproductive performance of zebrafish. Therefore, low pH has a significant effect on reducing the reproductive performance of zebrafish. The local fish population can be affected by the decrease of pH level due to acid rains and chemical waste pollution.

Matched MeSH terms: Acid Rain
Fulltext Antifungal efficacy of crude aqueous weed extracts against pathogen of cocoa black pod rot

Nor Amerulah Nor Mohamad, Suhaida Salleh, Hamzah Abdul Aziz

Borneo Akademika, 2019;3(2):12-22.
MyJurnal

Black pod rot is the most economically important disease of cocoa in Malaysia which is
mainly caused by a highly polyphagous Phytophthora species, called Phytophthora palmivora.
The fungus could attack all parts of the cocoa plant organs and caused various diseases at
any growth stage from seedling until the mature stages, especially during raining season. The
application of synthetic fungicides has been widely recommended to manage the disease but
their repeated use had led to other problems such as environmental, human health and
development of fungicide resistance issues. This study isolated and identified Phytopththora
isolate from a cocoa pod sample based on micro-morphological characters. Besides, the
present investigation was undertaken to screen for the antifungal potency of different weed
extracts against the Phytophthora pathogen using poisoned food technique. The fungal isolate
was successfully recovered from pod tissues of clone PBC123 on 20% tomato juice agar
culture (20T). Only one out of ten weed extracts tested showed a significant in vitro inhibitory
effect towards mycelial growth of Phytophthora isolate, which was aqueous crude leaf extract
of Solanum torvum (42.68%). This study indicated that the potential of weed extracts in the
management of Phytophthora diseases, and may offer more natural, effective and economical
control methods.

Matched MeSH terms: Rain
Fulltext Temporal fluctuations of insecticides resistance in Musca domestica Linn (Diptera: Muscidae) in Malaysia

Bong LJ, Zairi J

Trop Biomed, 2010 Aug;27(2):317-25.
PMID: 20962731 MyJurnal

House flies were collected from April 2007-April 2008 from two poultry farms (Balik Pulau and Juru) in the state of Penang. The resistance level of the first generation offspring was evaluated against DDT, malathion, propoxur, and permethrin using the topical application method. The resistance ratio (RR) of the Balik Pulau strain house flies for propoxur, malathion and DDT ranged from 10.28 to 99.00, 7.83 to 47.01 and 6.05 to 31.10, respectively. Resistance to propoxur and malathion in house fly was attributed to cross resistance to organophosphate insecticides used in the farm. Increased metabolic detoxification might be the mechanism involved in DDT resistance due to excessive application of cypermethrin formulation. The RR of the Juru strain for propoxur, malathion and DDT was in a decreasing pattern throughout the study period, ranging from 5.58 to 83.38, 15.19 to 27.82, and 10.04 to 22.69, respectively. Permethrin appeared to be the most potent insecticide in controlling house fly in both the Balik Pulau (RR=0.50 to 1.96) and Juru poultry farms (RR=0.64 to 2.40). The fluctuations of insecticides resistance in house fly was also found to correlate with climatic factors due to its rapid breeding. Relative humidity exhibited positive correlation indices with the changes in the resistance level for DDT (r=0.481, p<0.05), malathion (r=0.698, p<0.01), and permethrin (r=0.580, p<0.05) in Balik Pulau. Similarly, relative humidity in Juru also showed strong correlation with the RR for DDT (r=0.900, p<0.01), malathion (r=0.762, p<0.05), permethrin (r=0.760, p<0.05), and propoxur (r=0.897, p<0.01).

Matched MeSH terms: Rain
Causes of variation between months in the distance traveled daily of gibbons

Raemaekers J

Folia Primatol., 1980;34(1-2):46-60.
PMID: 7439871

The monthly medians of the distances traveled daily by siamang and lar gibbons are negatively correlated with rainfall and positively correlated with the separate and combined abundance of different food categories. The latter correlations indicate that the apes follow a policy of cutting their losses by reducing travel when food abundance falls.

Matched MeSH terms: Rain
Crash severity along rural mountainous highways in Malaysia: An application of a combined decision tree and logistic regression model

Rusli R, Haque MM, Saifuzzaman M, King M

Traffic Inj Prev, 2018;19(7):741-748.
PMID: 29932734 DOI: 10.1080/15389588.2018.1482537

OBJECTIVE: Traffic crashes along mountainous highways may lead to injuries and fatalities more often than along highways on plain topography; however, research focusing on the injury outcome of such crashes is relatively scant. The objective of this study was to investigate the factors affecting the likelihood that traffic crashes along rural mountainous highways result in injuries.
METHOD: This study proposes a combination of decision tree and logistic regression techniques to model crash severity (injury vs. noninjury), because the combined approach allows the specification of nonlinearities and interactions in addition to main effects. Both a scobit model and a random parameters logit model, respectively accounting for an imbalance response variable and unobserved heterogeneities, are tested and compared. The study data set contains a total of 5 years of crash data (2008-2012) on selected mountainous highways in Malaysia. To enrich the data quality, an extensive field survey was conducted to collect detailed information on horizontal alignment, longitudinal grades, cross-section elements, and roadside features. In addition, weather condition data from the meteorology department were merged using the time stamp and proximity measures in AutoCAD-Geolocation.
RESULTS: The random parameters logit model is found to outperform both the standard logit and scobit models, suggesting the importance of accounting for unobserved heterogeneity in crash severity models. Results suggest that proportion of segment lengths with simple curves, presence of horizontal curves along steep gradients, highway segments with unsealed shoulders, and highway segments with cliffs along both sides are positively associated with injury-producing crashes along rural mountainous highways. Interestingly, crashes during rainy conditions are associated with crashes that are less likely to involve injury. It is also found that the likelihood of injury-producing crashes decreases for rear-end collisions but increases for head-on collisions and crashes involving heavy vehicles. A higher order interaction suggests that single-vehicle crashes involving light and medium-sized vehicles are less severe along straight sections compared to road sections with horizontal curves. One the other hand, crash severity is higher when heavy vehicles are involved in crashes as single vehicles traveling along straight segments of rural mountainous highways.
CONCLUSION: In addition to unobserved heterogeneity, it is important to account for higher order interactions to have a better understanding of factors that influence crash severity. A proper understanding of these factors will help develop targeted countermeasures to improve road safety along rural mountainous highways.

Matched MeSH terms: Rain
Variations des caractéristiques des huiles de palme et notamment de leurs caroténoides

Bienaymé A, Servant M

Qualitas Plantarum et Materiae Vegetabiles, 1958;3-4:336-353.
DOI: 10.1007/BF01884062

During two years the authors have assembled monthly analytical data of oilpalms, from 15 different stations. The determinations spread as far as the French, Portuguese and Spanish territory in Africa and British Malaya also. The following analyses were carried out: iodine number, titer point, melting point and the carotenoids of these oils, according to origine, race and time of gathering. As to iodine number and amount of carotenoid, the race is decisive for these data; the oils from the natural stock of the Ivory Coast have a higher iodine number (57-60). The oils from the natural stock of Togo, Dahomey, Portuguese and French Guinea are richer in carotene (up to 0.16, even 0.19%) with medium iodine number (54-56). The oils from the industrial plantations, with selected trees of the race Dura-Deli, from the Far East as well as from the Ivory Coast, have lower iodine numbers (52-53) and are poor in carotene (0.05). South of the equator in Africa, all analysed races of oil palms had a lower iodine number (53-55) and were poor in carotene (0.05). During one year the amount of carotene fluctuates about one third of its maximum; this maximum is rather striking in Togo and Dahomey; it is to be found from January to May; period of high production of the oil in the Palm groves, e.g. in the dry season with warm climate and good insolation. Heavy rain-showers effect a rapid decrease of the contents of carotene after six weeks (duration of the formation of the fruit). Furthermore, the residual oils (extracted by solvents) were analysed; they are 2 to 3 times richer in carotenoids than the common palm oil; but the contents of β-carotene seems somewhat lower. The authors think it possible to find exactly defined uses for the different oils. © 1958 Uitgeverij Dr. W. Junk.

Matched MeSH terms: Rain
Fulltext The link between climate change, food security and fertility: The case of Bangladesh

Chen M, Atiqul Haq SM, Ahmed KJ, Hussain AHMB, Ahmed MNQ

PLoS One, 2021;16(10):e0258196.
PMID: 34673797 DOI: 10.1371/journal.pone.0258196

Climate change is likely to worsen the food security situation through its impact on food production, which may indirectly affect fertility behaviour. This study examines the direct and indirect effects of climate change (e.g., temperature and precipitation) via the production of major crops, as well as their short- and long-term effects on the total fertility rate (TFR) in Bangladesh. We used structural equation modelling (SEM) to perform path analysis and distinguish the direct influence of climate change on fertility and its indirect influence on fertility through food security. We also applied the error correction model (ECM) to analyze the time-series data on temperature and precipitation, crop production and fertility rate of Bangladesh from 1966 to 2015. The results show that maximum temperature has a direct effect and indirect negative effect-via crop production-on TFR, while crop production has a direct positive effect and indirect negative effect-via infant mortality-on TFR. In the short term, TFR responds negatively to the maximum temperature but positively in the long term. The effect of rainfall on TFR is found to be direct, positive, but mainly short-term. Although indicators of economic development play an important part in the fertility decline in Bangladesh, some climate change parameters and crop production are non-negligible factors.

Matched MeSH terms: Rain
The status and characteristics of eutrophication in tropical coastal water

Peyman N, Tavakoly Sany SB, Tajfard M, Hashim R, Rezayi M, Karlen DJ

Environ Sci Process Impacts, 2017 Aug 16;19(8):1086-1103.
PMID: 28776620 DOI: 10.1039/c7em00200a

A set of methodological tools was tested to assess the sensitivity of several ecological and biological indices to eutrophication while at the same time attempting to explore a linkage among pressures, classification assessment and drivers. Industrial discharges, harbor activities, natural interactions and river discharges are the pressures most related to the eutrophication process in tropical coastal water bodies. Among the eutrophication indices used, TRIX and operational indicators overestimated the eutrophication status in the study area, but EI and chl-a seems to be a rather responsive index to reflect the first stage of eutrophication. It is noteworthy that EI and chl-a showed better overall agreement with the ecological quality status (EcoQ) showing that probably it reflects the indirect relation of macrobenthic with water eutrophication in a better way. An ecological boundary of EI and chl-a from moderate to poor may be needed in order to explain the poor status of relatively eutrophic Klang Strait coastal sites.

Matched MeSH terms: Rain
Influence of variations in rainfall pattern on the hydrogeochemistry of coastal groundwater-an outcome of periodic observation

Rajendiran T, Sabarathinam C, Chandrasekar T, Keesari T, Senapathi V, Sivaraman P, et al.

Environ Sci Pollut Res Int, 2019 Oct;26(28):29173-29190.
PMID: 31392611 DOI: 10.1007/s11356-019-05962-w

This study considered the temporal variations in rainfall and water level patterns as governing factors, which influence the geochemical process of coastal aquifer around Pondicherry, South India. Rainfall and water level data were collected from 2006 to 2016, which showed that the amount of rainfall from 2006 to 2011 was higher than that of 2011 to 2016. To understand the geochemical process governing groundwater, samples were collected during 2006 (n = 54), followed by 2011 (n = 93), and during 2016 (n = 63) as part of continuous observation. The major ions and stable isotopes (δ18O and δD) were analyzed in the samples to determine the geochemical variations. The predominant types were noted as Na-HCO3 and Na-Cl; Ca-HCO3 and Ca-Mg-Cl; and Na-Cl and Ca-Mg-Cl in 2006, 2011, and 2016, respectively. Saturation states of sulfate and carbonate minerals were compared for the study periods and it indicates that the saturation index (SI) values were increased from 2006 to 2011, but decreased from 2011 to 2016. PHREEQC inverse modeling revealed the predominance for the dissolution and leaching of carbonate minerals during increased rainy periods, and the increase of halite saturation during lesser rainfall period. AQUACHEM mixing studies suggested that geochemical signatures of 2006 and 2011 were preserved in samples of 2016 in different proportions. Considering the major factors, the main processes prevailing in the study area were inferred to be dissolution and leaching during 2006~2011 years and seawater intrusion along with ion exchange during 2011~2016 years. In all these periods of study, anthropogenic impact was also identified in the groundwater samples. Hence, this study revealed that the rainfall and water level gave a significant variation in the geochemical process of groundwater in the coastal aquifer system.

Matched MeSH terms: Rain

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