Northeast Monsoon Season Research Articles

Seasonality of Fish Juvenile Community Structure and Diversity in a Tropical Seagrass Meadow of Watamu, Kenya

Seagrass are important marine habitats that function as nursery grounds for juvenile fish. Human activities and other natural factors have contributed to their decline, and this has compromised their role as nurseries, specifically in non-continuous patchy seagrass beds. In this study, juvenile fish abundance from tropical seagrass beds of Watamu were examined, while testing the hypothesis that seagrass cover and seasonality influenced juvenile fish abundanceand diversity. Two sampling stations were identified, Watamu Blue Lagoon (WBL) and Watamu Beach (WB), based on seagrass cover, and were sampled for a period of 10 months that included two south-east monsoon (SEM) and two north-east monsoon (NEM) seasons. Monthly samples were collected by seining within the shallow seagrass habitats of WBL and WB. A total of 31 juvenile fish families were obtained, the dominant taxa being Lutjanidae and Siganidae. Seasonal and interannual variability in juvenile abundance was observed over the two years (p<0.05); year 1 recorded higher abundance than year 2, specifically during the SEM. In year 2 a higher mean abundance was recorded during the NEM when compared to the SEM. Chlorophyll a (p<0.05) and salinity (p<0.05) were found to significantly influence juvenile fish abundance.

Cetacean sightings and acoustic detections in the offshore waters of the Maldives during the northeast monsoon seasons of 2003 and 2004

Despite its central position in the Indian Ocean Sanctuary, little is known about the offshore cetacean fauna of the Maldives. Here we report survey results gathered by the R/V Odyssey in the Maldives during the 2003 and 2004 northeast monsoon seasons, and provide data on cetaceans from visual and acoustic observations. The survey was conducted over a period of 72 days and covered 10,915 track line kilometres. The main aim of the survey was to collect biopsy samples from sperm whales (Physeter macrocephalus) as part of a global survey of ocean pollutants. Totals of 157 sightings and 1,461 acoustic detections of 16 identified cetacean species were recorded. Risso’s dolphin (Grampus griseus), pantropical spotted dolphin (Stenella attenuata), spinner dolphin (Stenella longirostris) and sperm whale were the most commonly sighted species. Sperm whales and pantropical spotted dolphins were particularly abundant in the southern Maldives. The cetacean acoustic detection rate was 2.5 times higher than in the eastern Indian Ocean and Western tropical Pacific, while the non-physeterid sighting rate was 1.7 times higher than the Eastern tropical Pacific and 6.7 times higher than the eastern Indian Ocean based on other research conducted by the R/V Odyssey using the same methodology. It is concluded that the Maldives has a diverse and seemingly abundant cetacean community.

Potential Impacts of Future Climate Changes on Crop Productivity of Cereals and Legumes in Tamil Nadu, India: A Mid-Century Time Slice Approach

Climate change is a terrible global concern and one of the greatest future threats to societal development as a whole. The accelerating pace of climate change is becoming a major challenge for agricultural production and food security everywhere. The present study uses the midcentury climate derived from the ensemble of 29 general circulation models (GCMs) on a spatial grid to quantify the anticipated climate change impacts on rice, maize, black gram, and red gram productivity over Tamil Nadu state in India under RCP 4.5 and RCP 8.5 scenarios. The future climate projections show an unequivocal increase of annual maximum temperature varying from 0.9 to 2.2°C for RCP 4.5 and 1.4 to 2.7°C in RCP 8.5 scenario by midcentury, centered around 2055 compared to baseline (1981–2020). The projected rise in minimum temperature ranges from 1.0 to 2.2°C with RCP 4.5 and 1.8 to 2.7°C under RCP 8.5 scenario. Among the monsoons, the southwest monsoon (SWM) is expected to be warmer than the northeast monsoon (NEM). Annual rainfall is predicted to increase up to 20% under RCP 4.5 scenario in two-third of the area over Tamil Nadu. Similarly, RCP 8.5 scenario indicates the possibility of an increase in rainfall in the midcentury with higher magnitude than RCP 4.5. Both SWM and NEM seasons are expected to receive higher rainfall during midcentury under RCP 4.5 and RCP 8.5 than the baseline. In the midcentury, climate change is likely to pose a negative impact on the productivity of rice, maize, black gram, and red gram with both RCP 4.5 and RCP 8.5 scenarios in most places of Tamil Nadu. The magnitude of the decline in yield of all four crops would be more with RCP 8.5 over RCP 4.5 scenario in Tamil Nadu. Future climate projections made through multi-climate model ensemble could increase the plausibility of future climate change impact assessment on crop productivity. The adverse effects of climate change on cereal and legume crop productivity entail the potential adaptation options to ensure food security.

Sources of water vapor and their effects on water isotopes in precipitation in the Indian monsoon region: a model-based assessment

Climate records of ratios of stable water isotopes of oxygen (δ18O) are used to reconstruct the past Indian monsoon precipitation. Identifying the sources of water vapor is important in understanding the role of monsoonal circulation in the δ18O values, to aid in monsoon reconstructions. Here, using an isotope-enabled Earth system model, we estimate the contributions of oceanic and terrestrial water vapor sources to two major precipitation seasons in India—the Southwest monsoon and the Northeast monsoon, and their effects on the δ18O in precipitation (δ18Op). We find that the two monsoon seasons have different dominant sources of water vapor because of the reversal in atmospheric circulation. While Indian Ocean regions, Arabian Sea, and recycling are the major sources of the Southwest monsoon precipitation, North Pacific Ocean and recycling are two crucial sources of Northeast monsoon precipitation. The δ18Op of the Southwest monsoon precipitation is determined by contributions from the Indian Ocean sources and recycling. Despite reduced precipitation, more negative δ18Op values are simulated in the Northeast monsoon season due to larger negative δ18Op contributions from the North Pacific. Our results imply that changes in atmospheric circulation and water vapor sources in past climates can influence climate reconstructions using δ18O.

Coupling SWAT and Bi-LSTM for improving daily-scale hydro-climatic simulation and climate change impact assessment in a tropical river basin

Global climate change has led to an increase in both the frequency and magnitude of extreme events around the world, the risk of which is especially imminent in tropical regions. Developing hydrological models with better capabilities to simulate streamflow, especially peak flow, is urgently needed to facilitate water resource planning and management as well as climate change mitigation efforts in the tropics. In view of the need, this paper explores the feasibility of improving streamflow simulation performance in the tropical Kelantan River Basin (KRB) of Peninsular Malaysia through coupling a conceptual process-based hydrological model − Soil and Water Assessment Tool (SWAT) with a deep learning model − Bidirectional Long Short-Term Memory (Bi-LSTM) in two ways. All SWAT parameters were set as their default values in one hybrid model (SWAT-D-LSTM), whereas three most sensitive SWAT parameters were calibrated in the other hybrid model (SWAT-T-LSTM). Comparison of daily streamflow simulation results have shown that SWAT-T-LSTM consistently performs better than SWAT-D-LSTM as well as the stand-alone SWAT and Bi-LSTM model throughout the simulation period. Particularly, SWAT-T-LSTM performs considerably better than the other three models in simulating daily peak flow. Based on the latest projection results of five GCMs from the Sixth Phase of the Coupled Model Intercomparison Project (CMIP6) under three emission scenarios (SSP1-2.6, SSP2-4.5, SSP5-8.5), the best-performed SWAT-T-LSTM was run to assess the potential impacts of climate change on streamflow in the KRB. Ensemble assessment results have concluded that both average and extreme streamflow is much likely to increase considerably in the already wet northeast monsoon season from November to January, which has surely raised the alarm for more frequent flood occurrence in the KRB.

The Impact of the Surrounding Land Uses on Water Quality of Some Selected Cascade and Perennial Tanks in Anuradhapura District, Sri Lanka

The present study was conducted to evaluate the water quality of the inlet, irrigation outlet, and edges linked to Nuwarawewa reservoir, Mahakanadarawa reservoir, Hurulu wewa reservoir, Sangilikandarawa reservoir, and Nachchaduwa perennial reservoir in Anuradhapura, Sri Lanka. Water samples were taken from a designated position of each inlet, irrigation output, and edges in the second inter-monsoon, northeast monsoon, and first inter-monsoon seasons. Water quality indicators such as pH, electrical conductivity (EC), total dissolved solids (TDS), Na, K, Ca, Mg, Sodium Adsorption Ratio (SAR), NO3- -N, NH4+-N, dissolved reactive phosphorus (DRP), and heavy metals (Cd, As, Pb, and Hg) concentrations were measured in each water sample. Data was analyzed using SPSS statistica software. Considerable temporal fluctuations in water quality indicators were detected in inlets, irrigation outflows, and edges over the research period. The findings revealed that NO3- -N, NH4+-N, and DRP in Sangilikandarawa reservoir during the northeast monsoon were close but not above the FAO (1985) maximum levels guidelines for irrigation water. pH, EC, TDS, and heavy metals (Cd, As, Pb, and Hg) in all the other tanks were within permitted values according to WHO drinking water quality standards and FAO (1985) guidelines for irrigation water. This finding further demonstrated that the consequences of surrounding land use on water pollution in inlet water canals linked to Sangilikandarawa and Nuwarawewa are greater. It could be concluded that a pollution management plan needs to be implemented in order to stop further pollution.

Evaluating the Increasing Trend of Strength and Severe Wind Hazard of Philippine Typhoons Using the Holland-B Parameter and Regional Cyclonic Wind Field Modeling

For the Philippines, a country exposed to multiple natural hazards, such as severe winds, sustainable development includes resiliency. A severe wind hazard is raised by tropical cyclones in the Western Pacific, known as typhoons, which frequent the Philippines. Therefore, adequately evaluating wind hazards and their impact is crucial for sustainable building design. Acknowledging the effects of climate change on said hazards requires adaptation to their consequences, which necessitates a deeper understanding of the changing behavior of typhoons in recent years. For this study, detailed wind information from the Japanese Meteorological Agency from 1977 to 2021, the Holland-B parameter, and the radius of maximum wind speed for each typhoon, are determined for simulation of the regional cyclonic wind field. The analysis of the Holland-B parameters, which represent the steepness of the pressure gradient and tropical cyclone convection, suggests that the Holland-B parameters have been increasing since 2011. The evaluation of the maximum regional wind fields and the return period wind fields caused by typhoons also indicate an increasing trend in severe wind hazards. Seasonality for the location of severe wind hazards is also observed, with Visayas and Mindanao experiencing an increase (decrease) during the Northeast (Southwest) Monsoon season and Luzon experiencing an increase (decrease) during the Southwest (Northeast) Monsoon season.

Seasonal Variability of Air Pollutants and Their Relationships to Meteorological Parameters in an Urban Environment

Air quality in urban areas is deteriorating over time with the increased pollutant distribution levels mainly caused due to anthropogenic activities. In addition, these pollutant distribution levels may relate to changing meteorological conditions. However, the relationships were not researched in-depth in the context of Sri Lanka, a country with a significant impact on climate change. The main objective of this study was to provide a broader perspective on the seasonal variation of tiny particles in air (PM2.5 and PM10), nitrogen dioxide (NO2), carbon monoxide (CO), ozone (O3), and sulfur dioxide (SO2) in two urban cities (Colombo and Kandy) in Sri Lanka over 3 years period (2018–2021) and the possible relationships between air pollution and meteorological variables. Results show that all the aforementioned pollutants except O3 consistently depict two peaks during the day, one in the morning (∼07:00–09:00 local time) and the other in the evening (∼18:00–20:00 local time). These peaks coincided with the traffic jams observed in both cities. The results further revealed that the concentration of all pollutants has significant seasonal variations. Compared to two monsoon seasons, the highest daily average PM2.5 (31.2 μg/m3), PM10 (49.5 μg/m3), NO2 (18.9 ppb), CO (717.5 ppb), O3 (18.5 ppb), and SO2 (9.4 ppb) concentrations in Colombo are recorded during northeast monsoon (NEM) seasons while contrast pattern is observed in Kandy. In addition, it was found that wind speed with its direction is the most influencing factor for the pollutant concentration except for SO2 and O3 in two cities, and this is irrespective of the season. This study’s findings contribute to understanding the seasonality of ambient air quality and the relationship between meteorological factors and air pollutants. These findings ultimately lead to designing and implementing season-specific control strategies to achieve air pollution reduction at a regional scale.

Exploring the effects of seasons, diurnal cycle, and heights on airborne pollen load in a Southeast Asian atmospheric condition.

Aeropollen can induce detrimental effects, particularly in respiratory airways. Monitoring local aeropollen is essential for the management of pollen allergic patients in each area. However, without resources for constant monitoring, pollen counts are subjected to biases imposed by the choices of sampling season, time of collection, and location. Therefore, the effects of these factors must be better understood. This study investigated the dynamics of aeropollen types through seasonal variation, diurnal cycle and different heights from the ground in Bangkok, Thailand. Aeropollen samples were collected for 12 months at the Faculty of Science, Mahidol University in Bangkok, using a RotoRod Sampler®. For the investigation of diurnal effect, pollen was collected at 7 a.m., 10 a.m., 1 p.m., 4 p.m., and 7 p.m. For the study of height effect, data were collected at 2, 10, and 18 meters above ground. This is the first study of the effects of diurnal cycle and height variation on airborne pollen count in Southeast Asia. The results showed the highest concentration of aeropollen was observed in November, which was at the beginning of the northeast monsoon season in Bangkok, whereas the lowest concentration was recorded in July (rainy season). Interestingly, the lowest airborne pollen concentration recorded in July was greater than the high level of most standards. Grass pollen was found as the major aeropollen. The highest total pollen concentration was detected at 1 p.m. The maximum pollen quantity was detected at 10 meters from the ground. However, the total aeropollen concentration was extremely high (>130 grains/m3) at all elevated heights compared to other studies that mostly found at lower height (approximately 1-2 m above ground). The result suggested that pollen concentrations of most pollen types increased as height increased. This study also illustrated the correlation between aeropollen quantity and local meteorological factors. This aeropollen survey reported that pollen concentration and diversity were affected by seasonal variation, diurnal cycle, and height from the ground. Understanding these relationships can help with predictions of aeropollen type and quantity.

Understanding the Mechanism of Currents through the Malacca Strait Study Case 2020 – 2022 : Mean state, Seasonal and Monthly Variation

The Malacca Strait is the importance waters for international shipping routes and more 200 cases of ship collisions in the period 1970-2015 in this strait. That is related to some a shallow depth waters with many small islands and strong current which is making this strait have a highest risk in certain seasons. The CMEMS data used to understanding of mechanism of current, illustrate the pattern and tranport volume. The research uses descriptive and the statistical methods to understanding of mechanism and variability of current. The analysis of current patterns and water level shows that during the monsoon winds active, the current always moves to the Andaman Sea, we called the southeast current system. The Northeast (NE) and Southwest (SW) monsoon wind is strongly influence to the mechanism of formation southeast current system, which causes the varition in sea level hight in eastern and western of Malacca Strait. During the NE monsoon season, the water masses of the South China Sea are push away into the Karimata Strait, causing the sea level in the eastern part to be higher than the western part and will increase the current speed. On the other hand, during the SW monsoon season, the water masses from the Karimata Strait is pushed away from the eastern part of the Malacca Strait which causes the sea level decrease and causes the current speed to weaken. Numbers eddies phenomenon were found at the Malacca Strait each season. The anticyclonic eddies occurred almost every season centered at 3° - 5° N, 97° - 100° E. Meanwhile anticyclonic eddies appear around the northern part of Sumatra centered at 4° - 5°N, 99° - 101°E during SW Monsoon season and the eddies formation also existed during the second transition monsoon season.

Nghiên cứu đánh giá tác động của trường thủy động lực đến địa hình đáy biển đảo Nam Yết – Trường Sa

This research assesses the impact of major marine hydrodynamic factors, such as waves, currents, and sea levels on the changing processes of the seabed topography and the coastlines of the Namyit (Nam Yết) Island of Truong Sa (Spratly) Islands, based on a many continuous years-data set. The study uses MIKE model to calculate and simulate the impact of wave field and current field on the process of accretion and erosion that changes the topography of the seabed. The results show that when comparing between calculated wave height, speed of the currents, and sea level height and those observed on scene are 69.1%, 54.5%, and 95.4% respectively. These figures meet the requirement of Nash Sutcliffe Efficiency, in which calculated sea level shows highest reliability. The research results provide an overview of wave and currents regimes in Northeast and Southwest monsoon seasons, and the characteristics of the current seabed topography around Namyit Island. The changing of seabed around Namyit Island includes diversified accretion and erosion. In the area from the depth of 10 m to the Island’ coastlines, the accretion dominant, with sediment thickness of up to 2.0 m. At 200 m West and East of the island, there have erosion areas, with sediment thickness reduces to 1.0 m. The changing of natural seabed topography of the researched area is mainly impacted by the process of accretion and erosion of sediment due to hydrodynamic regimes (waves, currents, and sea levels fluctuations) and the development and decline of seabed coral system. The research results are the scientific basis for planning, and proposing the construction around the island, planning for navigation channels dredging, and providing information for naval training, exercises, and operations around offshore islands.

The Exploration of the Changes In Surface Ozone by Region and Season

The growth of air pollution as a serious concern throughout the country is influenced by several causes sourcing from transportation, combustion, and industrialization. These factors reduced the air quality which harms society, animals, and plants’ well-being. Surface ozone is one of the main causes of air pollution in developing areas around the world. Analysis of surface ozone by area and season variations increased during summer were associated with meteorological parameters such as atmospheric temperature and humidity, meanwhile, the concentration of surface ozone is low during the northeast monsoon season. In addition, the concentration of surface ozone also increases when there are other environmental influences such as the release of pollutants from anthropogenic activity. Therefore, a study will be carried out to identify the variation of surface ozone concentrations by region and monsoon season in peninsular Malaysia, especially in the northern, eastern, and western zones, to identify the highest duration for daily ozone concentration (O3) and to study the relationship between the monthly and annual surface ozone concentrations with meteorological parameters. The results in this study can be used to identify air quality and address the problem of air pollution so that human health and the environment are preserved by using the method of boxplot and line graph obtained from descriptive statistics.

Bioengineering by the alien false mussel Mytilopsis sallei (Bivalvia: Dreissenidae) affects small-scale distribution pattern of benthic macroinvertebrates in an estuarine system

ABSTRACT The false mussel Mytilopsis sallei (Récluz, 1849) invaded the Songkhla Lagoon System in southern Thailand more than two decades ago. The false mussel forms dense beds, creating three-dimensional habitat structures on soft substrata which harbour a myriad of organisms. We compare a community of benthic macroinvertebrates in a habitat modified by M. sallei with a community in an unmodified habitat. The study focused on a canal feeding into the southern end of the lagoon system and covered three seasons (north-east monsoon season, dry season and south-west monsoon season) in a 12-month period. A total of 26 taxa were present in the modified habitat and 22 in the unmodified habitat. In the modified habitat, abundances of other byssally attached bivalves, flatworms and some species of amphipods were more than an order of magnitude greater than abundances in the unmodified habitat. Differences in the community composition between habitats were observed but were dependent on sampling location and time. Although the modified habitat hosted greater numbers of species and individuals in most comparisons, the Shannon–Wiener index and Pielou's evenness index were lower for this habitat as it tended to be dominated by a few taxa. The results highlight the role of M. sallei as a habitat engineer that promotes species richness and abundance of some benthic macroinvertebrates. Nonetheless, temporal variation in environmental drivers, especially salinity, might also be important in determining biodiversity in the studied estuarine system.

Rainfall Spatial-Temporal Variability and Trends in the Thamirabharani River Basin, India: Implications for Agricultural Planning and Water Management

Rainfall is critical to agricultural and drinking water supply in the Thamirabharani river basin. The upper catchment areas of the Thamirabharani basin are located in high-elevated forest regions, and rainfall variability affects dam inflow and outflow. The well-known methods for rainfall analysis such as the coefficient of variation (CV), the precipitation concentration index (PCI), and trend analysis by Mann-Kendall and Sen’s slope test, as well as the Sen’s graphical innovative trend method (ITA) recently reported in several studies, were used. Rainfall data from gauge stations and the satellite-gridded Multisource Weighted Ensemble Precipitation (MSWEP) dataset were chosen for analysis at the annual and four-season time scales, namely, the Southwest Monsoon, Northeast Monsoon, winter, and summer seasons from 1991 to 2020. The mean annual PCI value reflects irregular monthly rainfall distribution (PCI > 20) in all gauge stations. The spatial monthly rainfall distribution of PCI values remarkedly shows a moderate distribution in the western and an anomalous distribution in the eastern part of the basin. The annual mean rainfall ranges from 718.4 to 2268.6 mm/year, decreasing from the high altitude zone in the west to the low plains and coastal regions in the east. Seasonal rainfall contributes about 42% from the NEM, 30.6% from the SWM, 22.8% from summer, and 3.9% from winter, with moderate variability (CV less than 30%). Ground stations experienced extremely high interannual variability in rainfall (more than 60%). Trend analysis by the MK, TFPW-MK, and ITA methods shows increasing annual rainfall in the plains and coastal regions of the basin; particularly, more variations among the seasons were observed in the Lower Thamirabharani sub-basin. The NEM and summer season rainfall are statistically significant and contribute to the increasing trend in annual rainfall. The ITA method performed better in the annual and seasonal scale for detecting the rainfall trend than the MK and TFPW-MK test. The Lower Thamirabharani sub-basin in the eastern part of the basin receives more rain during the NEM than in other areas. To summarize, the low plains in the central and coastal regions in the southeast part experience an increase in rainfall with irregular monthly distribution. This study helps farmers, governments, and policymakers in effective agricultural crop planning and water management.

Seasonal Occurrence and Relative Abundance of Marine Fish Larval Families over Healthy and Degraded Seagrass Beds in Coastal Kenya

Seagrass beds provide critical nursery habitats and spawning grounds for new generations of fish. The habitats are under threat from human activities and climate change, and with that, an important ocean service is lost that limits fish production. The present study investigates patterns in the larval occurrence and abundance in seagrass meadows at two locations with varying degrees of seagrass fragmentation. Monthly ichthyoplankton sampling was conducted during the northeast monsoon (NEM) and southeast monsoon (SEM) seasons in 2019 and 2020. A total of 42 larval fish families belonging to 37 genera and 21 species were identified. Dominant families were Labridae (29.5%), Blenniidae (28.7%), Gobiidae (26.0%), Engraulidae (23.3%) and Scaridae (22.3%). Canonical Correspondence Analysis and regression analysis revealed water temperature, dissolved oxygen and pH as the most important abiotic variables driving taxonomic composition of larval assemblages, while zooplankton and chlorophyll-a were the most important biotic factors. Fish larvae were more abundant in healthy seagrass habitats as compared to degraded ones. However, despite some loss in functionality, the degraded sites equally played a role in supporting some species, including Gobiidae and Blenniidae. Seasonality influenced larval abundance at the two sites, with a peak in mean abundance coinciding with the NEM season. Interannual variability in fish larval abundance was observed at both sites, indicating that factors controlling larval production varied between the years. This study demonstrates the important role of seagrass meadows in the replenishment of fish stocks and supportive evidence for their management and conservation.

Abundance, Source Apportionment and Health Risk Assessment of Polycyclic Aromatic Hydrocarbons and Nitro-Polycyclic Aromatic Hydrocarbons in PM2.5 in the Urban Atmosphere of Singapore

In this study, the levels of fine particulate matter (PM2.5), polycyclic aromatic hydrocarbons (PAHs) and nitro-PAHs (NPAHs) in PM2.5 samples were determined from 2020 to 2021 in Singapore. For analysis convenience, the sampling period was classified according to two monsoon periods and the inter-monsoon period. Considering Singapore’s typically tropical monsoon climate, the four seasons were divided into the northeast monsoon season (NE), southwest monsoon season (SW), presouthwest monsoon season (PSW) and prenortheast monsoon season (PNE)). The PM2.5 concentration reached 17.1 ± 8.38 μg/m3, which was slightly higher than that in 2015, and the average PAH concentration continuously declined during the sampling period compared to that reported in previous studies in 2006 and 2015. This is the first report of NPAHs in Singapore indicating a concentration of 13.1 ± 10.7 pg/m3. The seasonal variation in the PAH and NPAH concentrations in PM2.5 did not obviously differ owing to the unique geographical location and almost uniform climate changes in Singapore. Diagnostic ratios revealed that PAHs and NPAHs mainly originated from local vehicle emissions during all seasons. 2-Nitropyrene (2-NP) and 2-nitrofluoranthene (2-NFR) in Singapore were mainly formed under the daytime OH-initiated reaction pathway. Combined with airmass backward trajectory analysis, the Indonesia air mass could have influenced Singapore’s air pollution levels in PSW. However, these survey results showed that no effect was found on the concentrations of PAHs and NPAHs in PM2.5 in Indonesia during SW because of Indonesia’s efforts in the environment. It is worth noting that air masses from southern China could impact the PAH and NPAH concentrations according to long-range transportation during the NE. The results of the total incremental lifetime cancer risk (ILCR) via three exposure routes (ingestion, inhalation and dermal absorption) for males and females during the four seasons indicated a low long-term potential carcinogenic risk, with values ranging from 10−10 to 10−7. This study systematically explains the latest pollution conditions, sources, and potential health risks in Singapore, and comprehensively analyses the impact of the tropical monsoon system on air pollution in Singapore, providing a new perspective on the transmission mechanism of global air pollution.

Assessment of vertical and horizontal distribution of meiobenthos along a salinity gradient in the Tana and Sabaki Estuaries, north coast Kenya

Meiobenthos respond to variability in salinity gradients in estuarine habitats and are thus suitable organisms for ecological studies. The vertical and horizontal distribution of the meiofauna community structure of two major estuaries (Sabaki and Tana) on the north coast of Kenya were compared. The aim was to draw a meiofaunal dataset inventory of the two estuaries and to examine how salinity gradient, seasonality and sediment characteristics influence their structure. Replicate samples were collected from three sampling stations along the salinity gradient of each river estuary. A total of 3,556 individuals belonging to 26 taxa were recorded. Based on seasons and across stations, the upper surface (0-5 cm) layer recorded the highest meiobenthic density (90 ± 42 ind.10 cm-2), followed by 46 ± 23 ind.10 cm-2 (5-10 cm) and 30 ± 8 ind.10 cm-2 in the deepest sediment layer (10-15 cm) studied. The southeast monsoon season recorded the highest mean density (160 ± 22 ind.10 cm-2) compared to the northeast monsoon season (22 ± 12 ind.10 cm-2) for both estuaries. Results of the non-Metric Multidimensional Scaling technique revealed distinct seasonal composition in meiobenthos but not between the estuaries. Results of the 2-way ANOSIM test confirmed no significant differences in meiobenthic composition between the estuaries (p = 0.712). However, seasonal difference was significant (p = 0.001) with higher densities for nematoda (166 ± 99 ind.10 cm-2 and 56 ± 29 ind.10 cm-2) recorded in Tana and Sabaki, respectively during the southeast monsoon season. At least 7 taxa out of a total of 26 were present in both estuaries. Salinity gradient, season and sediment depth were found to influence the meiobenthic densities and taxa composition.

Effect of Liquid Urea on Growth and Yield of Grain Corn (Zea mays L.)

ABSTRACT Efficient nitrogen management is the key strategy for sustainable crop production. A two-season (south-west and north-east monsoon season) experiments were conducted in Ladang 15, Faculty of Agriculture, Universiti Putra Malaysia in 2020 to compare the effect of liquid (LU) and granular urea (GU) on growth and yield of grain corn. The treatments were T0 = No urea (Control), T1 = GU (100%) at 10 days after sowing (DAS) and 28 DAS, T2 = LU (100%) at 10 and 28 DAS, T3 = LU (100%) at 10, 40 and 65 DAS, T4 = LU (50%) at 10 and 28 DAS and T5 = LU (50%) at 10, 40 and 65 DAS. Plant height, stem diameter, ear height and dry grain weight were higher in season 1 (south-west monsoon), but other growth and yield parameters were similar to season 2 (north-east monsoon). The highest cob diameter (5.43 and 5.30 cm), kernel rows/cob (17.30 and 16.72), seeds/row (38.88 and 36.96) and fresh cob weight (325.45 g and 319.18 g) were recorded from T3 and T5 treatments but the highest 100-grain weight resulted in T3 (50.51 g) and T2 (49.02 g) treatments. The highest grain yield (11,019.23 kg/ha) was recorded in T3 treatment. The highest total N content was recorded in T3 (161.92 kg/ha) treatment followed by T2 (141.04 kg/ha). In addition, the highest NUE was recorded in T3 (77.42%) and T5 (75.42%) treatments. As a result, the three splits application of LU was the most efficient application method for maximizing the growth and yield of grain corn.

Correlation, Regression Analysis, and Spatial Distribution Mapping of WQI for an Urban Lake in Noyyal River Basin in the Textile Capital of India

Nowadays, the major threat to humans occurs due to water quality deterioration. The quality of water creates a new sign for the public to prevent them from waterborne diseases. This study uses sensitive water quality parameters obtained from the northeast monsoon season, October 2021, at different locations in Mooli Kulam lake (11°07′17.6″ N, 77°22′59.9″ E) of Tiruppur District, Tamil Nadu, India. The parameters considered for the analysis of lake water quality are closely included with drinking and irrigation parameters. The northeast monsoon samples collected from the lake were analysed and the Water Quality Indexing was applied to the dataset using three methods, namely, the Weight Arithmetic method, the Canadian Council of Ministers of the Environment, and Horton’s method. The parameters are divided into drinking water variables and irrigation water variables. This study includes water quality index mapping using Inverse Distance Weighting interpolation of the spatial distribution method using ArcMap 10.8. The dataset was subjected to correlation and regression analysis in order to determine the most significant pollutant. A total of 10 sampling stations and 23 water quality parameters have been analysed. The results obtained show that the lake has high eutrophication with compounds of potassium, iron, and nitrates.

Alive and dead foraminiferal assemblages at sandy beaches of Karachi coast-diversity, ecological distribution and responses to seasonal fluctuations

Foraminifera are eukaryotic protists and play a vital role in marine community structure. However, how physicochemical environment shape meiofaunal community structure at highly dynamic exposed sandy beaches of Arabian sea is inadequately known. This is the first study about spatiotemporal distribution of alive and dead benthic foraminiferal (BF) species from coastal regions of Pakistan based on 48 core samples collected monthly with the help of hand corer (diameter = 3 cm) from four stations at two sandy beaches of Karachi coast i.e., Sandspit and Hawksbay. Sampling was done throughout the year from March 2013 to April 2014 to observe seasonal variability in southwest and northeast monsoon season. Physicochemical parameters (temperature, salinity, pH, dissolved oxygen and nutrients i.e. Ammonia, nitrate and phosphorus) and sediment characteristics (grain size, moisture content, organic content) was analysed using standard methods.The top 0–2 cm sediment slice was analysed for both living and dead foraminiferal assemblages. A sum of 6615 individuals (ind.) cm−2 of BF consisting of 3451 ind. cm−2 empty tests and 3164 ind. cm−2 living specimens belonged to 66 species were recorded, where 47% species are Miliolina, 42% Rotaliida, 9% Textulariina and 2% are Spirillinina. The similarity percentage breakdown analysis (SIMPER) showed 18.51% average dissimilarity between foraminifera abundance at Sandspit and Hawksbay but stations within sites showed similarity (82.83% at Sandspit and 84.65% at Hawksbay). The highest abundance of alive BF was recorded in northeast monsoon season (3232 ind. cm −2) associated with high levels of nutrients. Alive and dead foraminifera assemblages at Karachi coast do not seem to be measured by a single physicochemical and environmental factor but multiple factors are controlling spatiotemporal distribution of BF at these beaches. The most significant and governing factor for benthic abundance and diversity at these beaches is the monsoon season.