Seasonal Variation of Phthalate Esters in Urban River Sediments: A Case Study of Fengshan River System in Taiwan

The Fengshan River system is one of the major rivers in Kaohsiung City, Taiwan. This study investigated the concentration of eight phthalate esters (PAEs) in sediments of the river and the impact of potential ecological risks during the dry and wet seasons. The potential risk assessment of sediment PAEs was evaluated by adopting the total risk quotient (TRQ) method. The total PAEs concentrations (∑PAEs) in the sediments of the Fengshan River system are between 490–40,190 ng/g dw, with an average of 8418 ± 11,812 ng/g dw. Diisononyl phthalate (38.1%), bis(2-ethylhexyl) phthalate (36.9%) and di-isodecyl phthalate (24.3%) accounted for more than 99.3% of ∑PAEs. The concentration of ∑PAEs in sediments at the river channel stations is higher during the wet season (616–15,281 ng/g dw) than that during the dry season (490–1535 ng/g dw). However, in the downstream and estuary stations, the wet season (3975–6768 ng/g dw) is lower than the dry season (20,216–40,190 ng/g dw). The PAEs in sediments of the Fengshan River may have low to moderate potential risks to aquatic organisms. The TQR of PAEs in sediments at the downstream and estuary (TQR = 0.13) is higher than that in the upstream (TQR = 0.04). In addition, during the wet season, rainfall transported a large amount of land-sourced PAEs to rivers, leading to increased PAEs concentration and potential ecological risks in the upper reaches of the river.

Download Full-text

Seasonal changes in water quality and macrophytes and the impact of cattle on tropical floodplain waterholes

Marine and Freshwater Research ◽

10.1071/mf12114 ◽

2012 ◽

Vol 63 (9) ◽

pp. 788 ◽

Cited By ~ 17

Author(s):

N. E. Pettit ◽

T. D. Jardine ◽

S. K. Hamilton ◽

V. Sinnamon ◽

D. Valdez ◽

...

Keyword(s):

Water Quality ◽

Seasonal Changes ◽

Aquatic Macrophyte ◽

Plant Cover ◽

Critical Role ◽

Dry Season ◽

Nutrient Concentrations ◽

Wet Season ◽

Dry Tropics ◽

The Impact

The present study indicates the critical role of hydrologic connectivity in floodplain waterholes in the wet–dry tropics of northern Australia. These waterbodies provide dry-season refugia for plants and animals, are a hotspot of productivity, and are a critical part in the subsistence economy of many remote Aboriginal communities. We examined seasonal changes in water quality and aquatic plant cover of floodplain waterholes, and related changes to variation of waterhole depth and visitation by livestock. The waterholes showed declining water quality through the dry season, which was exacerbated by more frequent cattle usage as conditions became progressively drier, which also increased turbidity and nutrient concentrations. Aquatic macrophyte biomass was highest in the early dry season, and declined as the dry season progressed. Remaining macrophytes were flushed out by the first wet-season flows, although they quickly re-establish later during the wet season. Waterholes of greater depth were more resistant to the effects of cattle disturbance, and seasonal flushing of the waterholes with wet-season flooding homogenised the water quality and increased plant cover of previously disparate waterholes. Therefore, maintaining high levels of connectivity between the river and its floodplain is vital for the persistence of these waterholes.

Download Full-text

Zooplankton community of Parnaíba River, Northeastern Brazil

Acta Limnologica Brasiliensia ◽

10.1590/s2179-975x3214 ◽

2015 ◽

Vol 27 (1) ◽

pp. 118-129 ◽

Cited By ~ 2

Author(s):

Ludmilla Cavalcanti Antunes Lucena ◽

Thaís Xavier de Melo ◽

Elvio Sergio Figueredo Medeiros

Keyword(s):

Water Management ◽

Biodiversity Conservation ◽

Zooplankton Community ◽

River System ◽

Dry Season ◽

Large Rivers ◽

Northeastern Brazil ◽

Wet Season ◽

Marginal Areas ◽

River Diversions

Aim:The objective of the present work is to present a list of species of zooplankton (Rotifera, Cladocera and Copepoda) from the Parnaíba River. Additionally, we provide comments on their distribution along the river, and between dry and wet seasons.MethodsZooplankton was collected with a plankton net (60 µm mesh) and concentrated into a volume of 80 mL for further analysis, during the dry (October 2010) and wet (April 2011) seasons. Sampling was restricted to the marginal areas at depths between 80 and 150 cm.ResultsA total of 132 species was recorded among the three zooplankton groups studied. During the dry season a total of 82 species was registered and 102 species was registered for the wet season. Rotifera contributed with 66.7% of the species, followed by Cladocera (26.5%) and Copepoda (6.8%).ConclusionsThe richness of species observed was high compared to other large rivers in Brazil. In the context of current policies for water management and river diversions in northeastern Brazil, the present study highlights the importance of this river system for biodiversity conservation.

Download Full-text

A Comparative Frequency Analysis of Maximum Daily Rainfall for a SE Asian Region under Current and Future Climate Conditions

Advances in Meteorology ◽

10.1155/2017/2620798 ◽

2017 ◽

Vol 2017 ◽

pp. 1-16 ◽

Cited By ~ 7

Author(s):

Velautham Daksiya ◽

Pradeep Mandapaka ◽

Edmond Y. M. Lo

Keyword(s):

General Circulation ◽

Daily Rainfall ◽

Circulation Model ◽

Dry Season ◽

Wet Season ◽

Climate Conditions ◽

Rainfall Extremes ◽

Annual Maximum Daily Rainfall ◽

The Impact ◽

Maximum Daily Rainfall

The impact of changing climate on the frequency of daily rainfall extremes in Jakarta, Indonesia, is analysed and quantified. The study used three different models to assess the changes in rainfall characteristics. The first method involves the use of the weather generator LARS-WG to quantify changes between historical and future daily rainfall maxima. The second approach consists of statistically downscaling general circulation model (GCM) output based on historical empirical relationships between GCM output and station rainfall. Lastly, the study employed recent statistically downscaled global gridded rainfall projections to characterize climate change impact rainfall structure. Both annual and seasonal rainfall extremes are studied. The results show significant changes in annual maximum daily rainfall, with an average increase as high as 20% in the 100-year return period daily rainfall. The uncertainty arising from the use of different GCMs was found to be much larger than the uncertainty from the emission scenarios. Furthermore, the annual and wet seasonal analyses exhibit similar behaviors with increased future rainfall, but the dry season is not consistent across the models. The GCM uncertainty is larger in the dry season compared to annual and wet season.

Download Full-text

IMPACT OF COVID-19 EVENT ON AIR POLLUTANTS OF PM2.5 AND PM10 IN JAKARTA, INDONESIA

Journal of Southwest Jiaotong University ◽

10.35741/issn.0258-2724.56.4.12 ◽

2021 ◽

Vol 56 (4) ◽

pp. 117-140

Author(s):

Nora Idiawati ◽

Sepridawati Siregar

Keyword(s):

Air Quality ◽

Control Strategies ◽

Dry Season ◽

Capital City ◽

Future Research ◽

Air Pollution Control ◽

Wet Season ◽

Two Cities ◽

Pm2.5 And Pm10 ◽

The Impact

As the capital city of Indonesia, the Province of Jakarta encounter a problem seriously of decreasing air quality. This study analyzes the air quality of two cities in Jakarta Province, Central Jakarta and South Jakarta, from March to June 2016–2020, and the impact of COVID-19 epidemic prevention and control actions on air quality. The combined air quality index (AQI) for two cities from 2016–2019, in the wet season, indicated that it has the lowest AQI with an average of 79, and the highest AQI occurred in the dry season with averaged 118. The distribution of the six AQI classes for two cities in dry season were 2%, 24%, 63%, 11%, 0%, and 0%, and in wet season, they were 10%, 48%, 39%, 3%, 0%, and 0%, respectively. The concentrations for PM2.5 and PM10 in March, April, May, and June 2016–2019 and those for 2020 were also analyzed in this study. Based on the data from the two cities, during March, April, May, and June 2020, the average PM2.5 decreased by 23.6%, 39.5%, 41.5%, and 13.3%, respectively, and the average PM10 decreased by 22.2%, 29.9%, 36.9%, and 29.8%, respectively, compared with that in March, April, May, and June 2016–2019. It is obvious that air quality greatly improved during the COVID-19 epidemic. This study presents beneficial information to policymakers for developing scientific air pollution control strategies and is a useful reference for future research in improving urban air quality.

Download Full-text

Patterns of Fish Assemblage, Growth, and Diet Composition in a Tropical River between Two Cascading Hydropower Dams

International Journal of Ecology ◽

10.1155/2021/6652782 ◽

2021 ◽

Vol 2021 ◽

pp. 1-10

Author(s):

Lee Nyanti ◽

Chen-Lin Soo ◽

Afina-Yian Chundi ◽

Elsa-Cordelia-Durie Lambat ◽

Alvinna Tram ◽

...

Keyword(s):

Fish Species ◽

Diet Composition ◽

Fish Assemblages ◽

Condition Factor ◽

Dry Season ◽

Growth Patterns ◽

Native Fish ◽

Wet Season ◽

Fish Samples ◽

The Impact

Construction of cascade dams has been shown to have impacts on fish assemblages and biodiversity. Yet, there is no literature on fish assemblages in the Murum River that connects the cascading Bakun and Murum dams in Sarawak, Malaysia. Hence, study on this modified ecosystem is necessitated to better understand the effects of the cascade dam construction on fish fauna. For this, fish samples were caught at five stations located along the river during both dry and wet seasons. Environmental parameters were taken concurrently with fish sampling. Length-weight relationship, condition factors, and diet composition of selected fish species in the river were also determined. The present study demonstrated that there are indications of the impact of cascading dams on the formation of a complex ecosystem in the Murum River, that is, changing from the shallow downstream of the Murum Dam to the deep transitional and inundated zone of the Bakun reservoir. The transitional zone in the Murum River exhibited the lowest fish species diversity, richness, and evenness during the dry season due to low pH and DO coupled with high turbidity. The biological indices improved when the water quality improved during the wet season. On the contrary, the diversity and evenness indices at the inundated tributary station decreased remarkably during the wet season, likely due to the migration of fish during the onset of the rainy season. This study showed that Barbonymus schwanenfeldii has a wider feeding habit which contributes to its higher distribution and abundance in the Murum River. The growth patterns of B. schwanenfeldii, Cyclocheilichthys apogon, Hampala macrolepidota, Lobocheilos ovalis, and Osteochilus enneaporos were better during wet than dry season. Overall, the condition factor of all native fish species in the Murum River was in poor to fair condition, whereas the exotic species, Oreochromis mossambicus, exhibited excellent condition (K value > 2) for both seasons. The increase in the number of O. mossambicus coupled with its high condition factor indicates biological intrusion and a potential threat to the native fish species in the Murum River. Continuous monitoring is essential to detect in-time risk issues associated with environmental degradation and biological invasion in this regulated and inundated river ecosystem.

Download Full-text

The effects of phthalates on Nereis diversicolor

10.7287/peerj.preprints.1776v1 ◽

2016 ◽

Author(s):

Ashwaq Alnemari ◽

Joerg Hardege

Keyword(s):

Culture System ◽

Phthalate Esters ◽

Aquatic Organisms ◽

Consumer Products ◽

Short Term ◽

Hediste Diversicolor ◽

Materials Used ◽

Dissolved Chemicals ◽

The Impact

Animals are exposed, in the natural environment, to a range of human activity related dissolved chemicals that are potentially impacting on their fitness. The animals responses to such stress determines its fitness, physiology and in case of chemical signals also its behaviour. If physical or chemical changes in the ecosystem make the detection of such a chemical impossible, then it can be reasonably assumed that vital behaviours of the animal will be significantly altered. Plastics are lighter, more durable, stronger and cheaper than other materials used for the same purposes, making them most suitable for producing a very broad range of goods and products. However, these same properties also make them serious environmental hazards i.e. they are easily carried and dispersed by water over long distances, and stopped by barriers and settle in the form of sediments that can persist for centuries. Phthalate esters are widely used as additives to offer flexibility to polyvinyl chloride (PVC) resins (Graham, 1973). DEHP and DMP are the most frequently used plasticizer in PVC formulas in consumer products (Metcalf et al. 1973; Carnevali et al. 2010). In general phthalate esters harmful environmental and human health effects are well documented and a range of studies documented harmful effects on both land and aquatic organisms (Metcalf et al. 1973; Lithner, et al. 2009). Neanthes (Nereis, Hediste) diversicolor is a bio-indicator species to monitor levels of pollution in a particular environment i.e. to by quantify levels of contaminant presents in the worms. Measuring these in N. diversicolor makes it possible to estimate and monitor levels of contamination in marine environments. The worms are easy to keep in laboratory conditions and can be collected in large numbers in the field and used as model species since the 1950s (Scaps, 2002). The main aim of this study is to investigate and determine the fate of phthalates in a Nereis culture system and to assess the impact of phthalates upon fitness such as feeding behaviours. For this worms are exposed to different concentration of DEHP (0.05, 2, and 10 ug/mL) over short term (days) and long term (3 months / lifespan). The aim of short term of exposure was to determine the fate of phthalates in a Nereis culture system to examine if phthalate degradation takes place. GC-MS is used to measure the phthalates. Liquid: liquid extraction was used to extract phthalates from water and worm tissue whereas accelerated solvent extraction was used to extract phthalates from sediment. The aim of long term of exposure was to investigate and assess the impact of phthalates on animals’ functional traits (feeding response).

Download Full-text

Amplification of black carbon light absorption induced by atmospheric aging: temporal variation at seasonal and diel scales in urban Guangzhou

10.5194/acp-2019-654 ◽

2019 ◽

Author(s):

Jia Yin Sun ◽

Cheng Wu ◽

Dui Wu ◽

Chunlei Cheng ◽

Mei Li ◽

...

Keyword(s):

Optical Properties ◽

Organic Carbon ◽

Black Carbon ◽

Light Absorption ◽

Dry Season ◽

Diurnal Fluctuation ◽

Absorption Enhancement ◽

Wet Season ◽

Diurnal Variability ◽

The Impact

Abstract. Black carbon (BC) is an important climate forcer in the atmosphere. Amplification of light absorption can occur by coatings on BC aerosols, an effect that remains one of the major sources of uncertainties for accessing the radiative forcing of BC. In this study, the absorption enhancement factor (Eabs) was quantified by the minimum R squared (MRS) method using elemental carbon (EC) as the tracer. Two field campaigns were conducted in urban Guangzhou at the Jinan university super site during both wet season (July 31–September 10, 2017) and dry season (November 15, 2017–January 15, 2018) to explore the temporal dynamics of BC optical properties. The average concentration of EC was 1.94 ± 0.93 and 2.81 ± 2.01 μgC m−3 in the wet and dry seasons, respectively. Mass absorption efficiency at 520 nm by primary aerosols (MAEp520) determined by MRS exhibit a strong seasonality (8.6 m2g−1 in the wet season and 16.8 m2g−1 in the dry season). Eabs520 was higher in the wet season (1.51 ± 0.50) and lower in the dry season (1.29 ± 0.28). Absorption Ångström exponent (AAE470-660) in the dry season (1.46 ± 0.12) were higher than that in the wet season (1.37 ± 0.10). Collective evidence showed that the active biomass burning (BB) in dry season effectively altered optical properties of BC, leading to elevated MAE, MAEp and AAE in dry season comparing to those in wet season. Diurnal Eabs520 was positively correlated with AAE470-660 (R2 = 0.71) and negatively correlated with the AE33 aerosol loading compensation parameter (k) (R2 = 0.74) in the wet season, but these correlations were significantly weaker in the dry season, which may be related to the impact of BB. This result suggests that lensing effect was dominating the AAE diurnal variability during the wet season. The effect of secondary processing on Eabs diurnal dynamic were also investigated. The Eabs520 exhibit a clear dependency on secondary organic carbon to organic carbon ratio (SOC/OC). Eabs520 correlated well with nitrate, implying that gas-particle partitioning of semi-volatile compounds may potentially play an important role in steering the diurnal fluctuation of Eabs520. In dry season, the diurnal variability of Eabs520 was associated with photochemical aging as evidenced by the good correlation (R2 = 0.69) between oxidant concentrations (Ox=O3+NO2) and Eabs520.

Download Full-text

Factors controlling primary productivity in a wet–dry tropical river

Marine and Freshwater Research ◽

10.1071/mf12299 ◽

2013 ◽

Vol 64 (7) ◽

pp. 585 ◽

Cited By ~ 8

Author(s):

S. J. Faggotter ◽

I. T. Webster ◽

M. A. Burford

Keyword(s):

Algal Blooms ◽

Algal Biomass ◽

Arid Zone ◽

River System ◽

Dry Season ◽

Trophic Levels ◽

Nutrient Inputs ◽

Tropical River ◽

Algal Production ◽

The Impact

Algal production in rivers fuels foodwebs, and factors controlling this production ultimately affect food availability. Conversely, excessive algal production can have negative effects on higher trophic levels. The present study examined permanent waterholes in a disconnected wet–dry tropical river to determine the controls on algal production. Primary production in this river system was high compared with arid-zone and perennially flowing tropical rivers. Phytoplankton biomass increased over the dry season but this appeared to be because waterhole volume decreased, due to evaporation. Nitrogen (N) was the key limiting nutrient for phytoplankton, with rapid N turnover times, depletion of particulate 15N-nitrogen reflecting increasing N fixationover the dry season, and N stimulation in phytoplankton bioassays. The waterholes were shallow, providing sufficient light for accumulation of benthic algal biomass. Exclosure experiments were also conducted to determine the impact of top–down control on benthic algal biomass, with no evidence that exclusion of fish and crustaceans increased benthic algal biomass. The shallow off-channel waterhole in our study had substantially higher concentrations of nutrients and chlorophyll a than did the on-channel waterholes. This suggests that future anthropogenic changes, such as increased water extraction and increased nutrient inputs, could make the waterholes more vulnerable to deteriorating water quality, such as e.g. algal blooms, low concentrations of dissolved oxygen.

Download Full-text

Seasonality and pathogen transmission in pastoral cattle contact networks

Royal Society Open Science ◽

10.1098/rsos.170808 ◽

2017 ◽

Vol 4 (12) ◽

pp. 170808 ◽

Cited By ~ 19

Author(s):

Kimberly VanderWaal ◽

Marie Gilbertson ◽

Sharon Okanga ◽

Brian F. Allan ◽

Meggan E. Craft

Keyword(s):

Water Resources ◽

Disease Outbreaks ◽

Dry Season ◽

Pathogen Transmission ◽

Contact Network ◽

Wet Season ◽

Contact Networks ◽

Contact Rates ◽

Animal Populations ◽

The Impact

Capturing heterogeneity in contact patterns in animal populations is essential for understanding the spread of infectious diseases. In contrast to other regions of the world in which livestock movement networks are integral to pathogen prevention and control policies, contact networks are understudied in pastoral regions of Africa due to the challenge of measuring contact among mobile herds of cattle whose movements are driven by access to resources. Furthermore, the extent to which seasonal changes in the distribution of water and resources impacts the structure of contact networks in cattle is uncertain. Contact networks may be more conducive to pathogen spread in the dry season due to congregation at limited water sources. Alternatively, less abundant forage may result in decreased pathogen transmission due to competitive avoidance among herds, as measured by reduced contact rates. Here, we use GPS technology to concurrently track 49 free-roaming cattle herds within a semi-arid region of Kenya, and use these data to characterize seasonal contact networks and model the spread of a highly infectious pathogen. This work provides the first empirical data on the local contact network structure of mobile herds based on quantifiable contact events. The contact network demonstrated high levels of interconnectivity. An increase in contacts near to water resources in the dry season resulted in networks with both higher contact rates and higher potential for pathogen spread than in the wet season. Simulated disease outbreaks were also larger in the dry season. Results support the hypothesis that limited water resources enhance connectivity and transmission within contact networks, as opposed to reducing connectivity as a result of competitive avoidance. These results cast light on the impact of seasonal heterogeneity in resource availability on predicting pathogen transmission dynamics, which has implications for other free-ranging wild and domestic populations.

Download Full-text

Spectral dependence of aerosol light absorption over the Amazon Basin

Atmospheric Chemistry and Physics ◽

10.5194/acp-11-8899-2011 ◽

2011 ◽

Vol 11 (17) ◽

pp. 8899-8912 ◽

Cited By ~ 48

Author(s):

L. V. Rizzo ◽

A. L. Correia ◽

P. Artaxo ◽

A. S. Procópio ◽

M. O. Andreae

Keyword(s):

Spectral Range ◽

Biomass Burning ◽

Spectral Dependence ◽

Amazon Basin ◽

Dry Season ◽

Negative Slope ◽

Forest Site ◽

Wet Season ◽

Aerosol Absorption ◽

The Impact

Abstract. In this study, we examine the spectral dependence of aerosol absorption at different sites and seasons in the Amazon Basin. The analysis is based on measurements performed during three intensive field experiments at a pasture site (Fazenda Nossa Senhora, Rondônia) and at a primary forest site (Cuieiras Reserve, Amazonas), from 1999 to 2004. Aerosol absorption spectra were measured using two Aethalometers: a 7-wavelength Aethalometer (AE30) that covers the visible (VIS) to near-infrared (NIR) spectral range, and a 2-wavelength Aethalometer (AE20) that measures absorption in the UV and in the NIR. As a consequence of biomass burning emissions, about 10 times greater absorption values were observed in the dry season in comparison to the wet season. Power law expressions were fitted to the measurements in order to derive the absorption Ångström exponent, defined as the negative slope of absorption versus wavelength in a log-log plot. At the pasture site, about 70 % of the absorption Ångström exponents fell between 1.5 and 2.5 during the dry season, indicating that biomass burning aerosols have a stronger spectral dependence than soot carbon particles. Ångström exponents decreased from the dry to the wet season, in agreement with the shift from biomass burning aerosols, predominant in the fine mode, to biogenic and dust aerosols, predominant in the coarse mode. The lowest absorption Ångström exponents (90 % of data below 1.5) were observed at the forest site during the dry season. Also, results indicate that low absorption coefficients were associated with low Ångström exponents. This finding suggests that biogenic aerosols from Amazonia have a weaker spectral dependence for absorption than biomass burning aerosols, contradicting our expectations of biogenic particles behaving as brown carbon. In a first order assessment, results indicate a small (<1 %) effect of variations in absorption Ångström exponents on 24-h aerosol forcings, at least in the spectral range of 450–880 nm. Further studies should be taken to assess the corresponding impact in the UV spectral range. The assumption that soot spectral properties represent all ambient light absorbing particles may cause a misjudgment of absorption towards the UV, especially in remote areas. Therefore, it is recommended to measure aerosol absorption at several wavelengths to accurately assess the impact of non-soot aerosols on climate and on photochemical atmospheric processes.

Download Full-text