Short-term changes of anthropogenic eutrophication with precipitation in tropical coastal waters (Guanabara Bay, Rio de Janeiro, Brazil)

2021 ◽  
Author(s):  
Tainan Fonseca ◽  
Roberta Bittencourt Peixoto ◽  
Luana Pinho ◽  
Leticia Cotrim da Cunha ◽  
Ricardo Pollery ◽  
...  
Keyword(s):  
Surface Waters ◽  
Coastal Waters ◽  
Urban Areas ◽  
Nutrient Dynamics ◽  
Winter Season ◽  
Nutrient Concentrations ◽  
Guanabara Bay ◽  
Short Term ◽  
Anthropogenic Eutrophication ◽  
Nitrate Concentrations

<p>Eutrophication in coastal waters caused by non-treated urban discharges has been considered one of the most important effects of global change. At tropical latitudes, nutrient dynamics may be especially intense due to increased metabolic responses supported by high temperatures and solar incidence throughout the year. In addition, short-term variations, such as in rainfall and the tidal regime, may determine important changes in nutrient concentrations and the subsequent trophic status of coastal waters, which are still neglected especially during nocturnal periods due to common logistical constraints. Here, we assessed 24-h variations of water quality during the winter season in a tropical eutrophic bay that receives large inputs of nutrients from non-treated urban effluents (Guanabara Bay, RJ, Brazil). We measured concentrations of dissolved forms of nutrients (nitrate, nitrite, N-ammoniacal, phosphate, and silicate) and carbon (DOC), and oxygen (DO) associated with temperature, salinity, and pH in surface waters each 2h over two daily cycles (July and August 2018). Water samples for nutrients and DOC were preserved for later analysis, while other variables were measured in the field. A biomonitoring system with a submersible pump was used to collect surface coastal waters without bubbling, and along a 70 m pipe from the beach to the field lab. In turn, meteorological data were obtained from a city weather station located ~6 Km from the sampling area. The monthly accumulated precipitation with respect to the 24-h cycle in July was ~70% lower than in August (58 and 16 mm, respectively), although only that in July has showed a rainfall event during the sampling period. As a result, average DOC and N-ammoniacal concentrations in surface waters were ~50% lower, while nitrate, silicate and DO concentrations ~56, 164 and 50 % higher, respectively, during the 24-h cycle in August compared to July. Also, waters were slightly more basic and less saltier in August, contrasting with similar average values of phosphate concentrations and temperature between both sampling periods. Finally, DO concentrations indicated an intense metabolism, varying from a peak of supersaturation with high solar incidence to net autotrophy (2 pm) to undersaturation values as a proxy of net heterotrophy after the nocturnal period (6 am). In conclusion, this short-term study showed that higher monthly accumulated precipitation may dilute high DOC and N-ammoniacal concentrations in coastal aquatic ecosystems undergoing anthropogenic eutrophication. On the other hand, silicate and nitrate concentrations might be related to higher runoff inputs from the watershed. The event of precipitation in July also confirmed a drastic increase in nitrate concentrations, likely due to inputs from the watershed. Therefore, our findings reveal the complexity of accumulated and immediate effects of rainfall on nutrient levels in tropical coastal waters, which  highlight the importance of biomonitoring studies specially in urban areas.</p>

scholarly journals Leaching Rate of Polychlorinated Biphenyls (PCBs) from Marine Paint Chips

2021 ◽  
Author(s):  
Allen D. Uhler ◽  
Jeffery H. Hardenstine ◽  
Deborah A. Edwards ◽  
Guilherme R. Lotufo
Keyword(s):  
Polychlorinated Biphenyls ◽  
Surface Waters ◽  
Leaching Rate ◽  
Short Term ◽  
Aroclor 1254 ◽  
Maintenance And Repair ◽  
Potential Source ◽  
Vessel Bottom ◽  
Dissolved Phase ◽  
Over Time

AbstractPolychlorinated biphenyls (PCBs) were added to certain marine vessel bottom paints as a plasticizer to improve the adhesion and durability of the paint. The most common PCB formulation used to amend such paints was Aroclor 1254. Fugitive Aroclor-containing paint chips generated from vessel maintenance and repair operations represent a potential source of PCB contamination to sediments. Limited published studies indicate that Aroclor-containing paint is largely inert and exhibits low PCB leaching into water; however, the rate and degree of leaching of PCBs from paint chips have not been directly studied. This laboratory-based study evaluated the rate and extent of leaching of PCBs from paint chips into freshwater. The results of this investigation demonstrate that the rate of PCB dissolution from paint chips decreased rapidly and exponentially over time. Based on this study, it is estimated that the rate of leaching of PCBs from paint chips would cease after approximately 3 years of exposure to water. When all leachable PCBs were exhausted, it is estimated that less than 1% of the mass of PCBs in the paint chips was amenable to dissolution. The results of this experiment suggest that Aroclor-containing paint chips found in sediments are likely short-term sources of dissolved-phase PCB to pore or surface waters and that the majority of the PCBs in paint chips remain in the paint matrix and unavailable for partitioning into water. Graphic Abstract

scholarly journals Predicting Aedes aegypti infestation using landscape and thermal features

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Camila Lorenz ◽  
Marcia C. Castro ◽  
Patricia M. P. Trindade ◽  
Maurício L. Nogueira ◽  
Mariana de Oliveira Lage ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Aedes Aegypti ◽  
Vector Control ◽  
Land Surface ◽  
Urban Areas ◽  
Negative Binomial ◽  
Control Strategies ◽  
Winter Season ◽  
Landsat 8 ◽  
Thermal Features

AbstractIdentifying Aedes aegypti breeding hotspots in urban areas is crucial for the design of effective vector control strategies. Remote sensing techniques offer valuable tools for mapping habitat suitability. In this study, we evaluated the association between urban landscape, thermal features, and mosquito infestations. Entomological surveys were conducted between 2016 and 2019 in Vila Toninho, a neighborhood of São José do Rio Preto, São Paulo, Brazil, in which the numbers of adult female Ae. aegypti were recorded monthly and grouped by season for three years. We used data from 2016 to 2018 to build the model and data from summer of 2019 to validate it. WorldView-3 satellite images were used to extract land cover classes, and land surface temperature data were obtained using the Landsat-8 Thermal Infrared Sensor (TIRS). A multilevel negative binomial model was fitted to the data, which showed that the winter season has the greatest influence on decreases in mosquito abundance. Green areas and pavements were negatively associated, and a higher cover of asbestos roofs and exposed soil was positively associated with the presence of adult females. These features are related to socio-economic factors but also provide favorable breeding conditions for mosquitos. The application of remote sensing technologies has significant potential for optimizing vector control strategies, future mosquito suppression, and outbreak prediction.

Occurrence of a multi-species diatom bloom dominated by Proboscia alata (Brightwell) Sandstorm along the southwest coast of India

2013 ◽  
Vol 42 (1) ◽  
Author(s):  
Lathika Cicily ◽  
K. Padmakumar ◽  
C. Asha Devi ◽  
V. Sanjeevan
Keyword(s):  
Cell Density ◽  
Coastal Waters ◽  
Monsoon Season ◽  
Late Summer ◽  
Nutrient Concentrations ◽  
Diatom Bloom ◽  
Southwest Coast Of India ◽  
Southwest Coast ◽  
Toxic Species ◽  
A Cell

AbstractThe present communication reports on the occurrence of a multi-species diatom bloom in the upwelled waters along the southwest coast of India. During the late summer monsoon season (September 2009) a multi-species diatom bloom with a pale green discoloration of the sea surface was observed in the coastal waters of southwest coast of India. The bloom spread over an area of approximately 15 km2 along the coastal waters off Kannur (Lat. 11°59.471 N, Long. 75°03.446 E). Total diatom cell density of the bloom area was 16 × 104 cells l−1. Proboscia (=Rhizosolenia) alata (Brightwell) Sandstrom constituted 90% of the total phytoplankton population. Other phytoplankton groups that contributed to the bloom population included Chaetoceros spp., Pseudo-nitzschia spp., Rhizosolenia spp., Coscinodiscus sp., Leptocylindrus danicus, Thalassiosira sp., and Bacteriosira sp. Among these Pseudo-nitzschia multiseries, a toxic species with the ability to produce potent neurotoxin domoic acid, was observed with a cell density of 4 × 103 cells l−1. Surface chlorophyll a concentration of the bloom region was 14.1 μg l−1. Nutrient concentrations of the bloom area were 0.01 μmol l−1 for NO2-N, 0.1 μmol l−1 for NO3-N, 0.83 μmol l−1 for PO4-P and 11.44 μmol l−1 for SiO4.

scholarly journals Virus isolation studies suggest short-term variations in abundance in natural cyanophage populations of the Indian Ocean

2006 ◽  
Vol 86 (3) ◽  
pp. 499-505 ◽  
Author(s):  
Martha R.J. Clokie ◽  
Andrew D. Millard ◽  
Jaytry Y. Mehta ◽  
Nicholas H. Mann
Keyword(s):  
Indian Ocean ◽  
Surface Waters ◽  
Molecular Diversity ◽  
Virus Isolation ◽  
Short Term ◽  
Distinct Subgroup ◽  
Time Points ◽  
The Indian Ocean ◽  
Long Timescales ◽  
Time Point

Cyanophage abundance has been shown to fluctuate over long timescales and with depth, but little is known about how it varies over short timescales. Previous short-term studies have relied on counting total virus numbers and therefore the phages which infect cyanobacteria cannot be distinguished from the total count.In this study, an isolation-based approach was used to determine cyanophage abundance from water samples collected over a depth profile for a 24 h period from the Indian Ocean. Samples were used to infect Synechococcus sp. WH7803 and the number of plaque forming units (pfu) at each time point and depth were counted. At 10 m phage numbers were similar for most time-points, but there was a distinct peak in abundance at 0100 hours. Phage numbers were lower at 25 m and 50 m and did not show such strong temporal variation. No phages were found below this depth. Therefore, we conclude that only the abundance of phages in surface waters showed a clear temporal pattern over a short timescale. Fifty phages from a range of depths and time points were isolated and purified. The molecular diversity of these phages was estimated using a section of the phage-encoded psbD gene and the results from a phylogenetic analysis do not suggest that phages from the deeper waters form a distinct subgroup.

scholarly journals Returning home to die: Circular labour migration and mortality in South Africa 1

2007 ◽  
Vol 35 (69_suppl) ◽  
pp. 35-44 ◽  
Author(s):  
Samuel J. Clark ◽  
Mark A. Collinson ◽  
Kathleen Kahn ◽  
Kyle Drullinger ◽  
Stephen M. Tollman
Keyword(s):  
South Africa ◽  
Rural Areas ◽  
Urban Areas ◽  
Terminal Illness ◽  
Event History Analysis ◽  
Historical Period ◽  
Short Term ◽  
History Analysis ◽  
Working Age

Aim: To examine the hypothesis that circular labour migrants who become seriously ill while living away from home return to their rural homes to convalesce and possibly to die. Methods: Drawing on longitudinal data collected by the Agincourt health and demographic surveillance system in rural northeastern South Africa between 1995 and 2004, discrete time event history analysis is used to estimate the likelihood of dying for residents, short-term returning migrants, and long-term returning migrants controlling for sex, age, and historical period. Results: The annual odds of dying for short-term returning migrants are generally 1.1 to 1.9 times (depending on period, sex, and age) higher than those of residents and long-term returning migrants, and these differences are generally highly statistically significant. Further supporting the hypothesis is the fact that the proportion of HIV/TB deaths among short-term returning migrants increases dramatically as time progresses, and short-term returning migrants account for an increasing proportion of all HIV/TB deaths. Conclusions: This evidence strongly suggests that increasing numbers of circular labour migrants of prime working age are becoming ill in the urban areas where they work and coming home to be cared for and eventually to die in the rural areas where their families live. This shifts the burden of caring for them in their terminal illness to their families and the rural healthcare system with significant consequences for the distribution and allocation of health care resources.

Actually Existing Platformization

2021 ◽  
Vol 120 (4) ◽  
pp. 715-731
Author(s):  
Niels van Doorn ◽  
Eva Mos ◽  
Jelke Bosma
Keyword(s):  
Urban Areas ◽  
Boundary Work ◽  
Voluntary Sector ◽  
Food Delivery ◽  
Social Mobilization ◽  
Short Term ◽  
Urban Settings ◽  
The Social ◽  
Path Dependent ◽  
Market Consolidation

In this article we examine the partnership as a heterogeneous boundary resource that enables platforms to generate dependencies, become locally embedded, and gain power in urban settings. Pushing back against narratives of platform-driven disruption, which tend to universalize and totalize platform power, we discuss three cases of what we term “actually existing platformization”—a path-dependent and locally situated process in which platform companies engage in various forms of “boundary work” with other actors seeking to retain and/or gain power. Each case focuses on a distinct industry: food delivery, short-term housing rental, and the social/voluntary sector. In each of these domains, we show how asset-light platforms initiate and develop partnerships as a frequently nebulous boundary resource that opens up potential avenues for (1) market consolidation, (2) logistical integration, (3) social mobilization, and/or (4) institutional legitimation. Such strategic moves, we argue, have become particularly pertinent following the COVID-19 pandemic, which has hit urban areas particularly hard and is intensifying certain social dependencies and institutional shortcomings that platforms are seeking to exploit.

Nutrient cycling differs between cropped soils with century-old and recently pyrolyzed biochar

2021 ◽  
Author(s):  
Victor Burgeon ◽  
Julien Fouché ◽  
Sarah Garré ◽  
Ramin Heidarian-Dehkordi ◽  
Gilles Colinet ◽  
...  
Keyword(s):  
Nutrient Cycling ◽  
Soil Solution ◽  
Nutrient Dynamics ◽  
Chemical Properties ◽  
Crop Productivity ◽  
Nutrient Concentrations ◽  
Soil Productivity ◽  
Long Term Effects ◽  
Mitigation And Adaptation

<p>The amendment of biochar to soils is often considered for its potential as a climate change mitigation and adaptation tool through agriculture. Its presence in tropical agroecosystems has been reported to positively impact soil productivity whilst successfully storing C on the short and long-term. In temperate systems, recent research showed limited to no effect on productivity following recent biochar addition to soils. Its long-term effects on productivity and nutrient cycling have, however, been overlooked yet are essential before the use of biochar can be generalized.</p><p>Our study was set up in a conventionally cropped field, containing relict charcoal kiln sites used as a model for century old biochar (CoBC, ~220 years old). These sites were compared to soils amended with recently pyrolyzed biochar (YBC) and biochar free soils (REF) to study nutrient dynamics in the soil-water-plant system. Our research focused on soil chemical properties, crop nutrient uptake and soil solution nutrient concentrations. Crop plant samples were collected over three consecutive land occupations (chicory, winter wheat and a cover crop) and soil solutions gathered through the use of suctions cups inserted in different horizons of the studied Luvisol throughout the field.</p><p>Our results showed that YBC mainly influenced the soil solution composition whereas CoBC mainly impacted the total and plant available soil nutrient content. In soils with YBC, our results showed lower nitrate and potassium concentrations in subsoil horizons, suggesting a decreased leaching, and higher phosphate concentrations in topsoil horizons. With time and the oxidation of biochar particles, our results reported higher total soil N, available K and Ca in the topsoil horizon when compared to REF, whereas available P was significantly smaller. Although significant changes occurred in terms of plant available nutrient contents and soil solution nutrient concentrations, this did not transcend in variations in crop productivity between soils for neither of the studied crops. Overall, our study highlights that young or aged biochar behave as two distinct products in terms of nutrient cycling in soils. As such the sustainability of these soils differ and their management must therefore evolve with time.</p>

Diversity, status and habitat usage of avifauna at sadar upazila, magura, Bangladesh

2021 ◽  
Vol 48 (2) ◽  
pp. 441-456
Author(s):  
Ashikur Rahman Shome ◽  
Md Mahabub Alam ◽  
Md Fazle Rabbe ◽  
Mohammad Mijanur Rahman ◽  
Mohammad Firoj Jaman
Keyword(s):  
Rural Areas ◽  
Urban Areas ◽  
Winter Season ◽  
Bird Species ◽  
Diversity Indices ◽  
Habitat Diversity ◽  
Seasonal Abundance ◽  
Line Transect ◽  
Common Myna ◽  
Rural And Urban

A study on diversity, status, and habitat preference of avifauna was conducted from November 2017 to October 2018 in Magura Sadar upazila, Magura. Data was collected through direct field observations using line-transect method. Field surveys were made for three days per month in both rural and urban sites. A total of 140 species of birds belonged to 18 orders and 48 families were reported. Among the total species, 55% (77 species) were non-passerines and 45% (63 species) passerines with the highest individuals were counted under order Passeriformes. Resident bird species were dominant (106 species, 75.71%) over migratory (34 species, 24.28%) species. Species richness was the highest in the rural areas (124 species, 88.57%) and occurrence was the highest in winter season (97 species, 69.29%). The maximum species were recorded from trees (87 species, 62.14%) as preferred habitat. In this study, in total 4,060 individuals of birds were counted and among them, 51.55% (n=2093) were observed in the rural areas and 48.45% (n=1967) were in the urban areas. The highest number of birds was found in December (10.34%, n=432) and seasonal abundance was the highest in winter (40.15%, n=1630). Abundance was the highest for Common Myna (5.76%, n=234) among all recorded species. Diversity indices showed that the bird species were the most diverse in the rural areas in the winter season and in July. Habitat diversity indices were the highest for trees and birds used different types of habitats at different times for roosting, breeding and feeding. Regarding the observation status, 29.28% species was very common, 4.28% common, 31.42% fairly common, and 35% were few. This baseline data indicate that this study site is significant from the ecological and conservation point of views. Therefore, further research is necessary to understand how this avian diversity is maintained in this ecological setting. Bangladesh J. Zool. 48(2): 441-456, 2020

Nutrient distribution in the Bosphorus and surrounding areas

2002 ◽  
Vol 46 (8) ◽  
pp. 59-66 ◽  
Author(s):  
E. Okuş ◽  
A. Aslan-Yilmaz ◽  
A. Yüksek ◽  
S. Taş ◽  
V. Tüfekçi
Keyword(s):  
Chlorophyll A ◽  
Black Sea ◽  
Nutrient Dynamics ◽  
Lower Layer ◽  
Water Quality Monitoring ◽  
Nutrient Concentrations ◽  
The Black Sea ◽  
Sea Of Marmara ◽  
Nutrient Distribution ◽  
Northwestern Shelf

As part of a five years monitoring project “Water Quality Monitoring of the Strait of Istanbul”, February-December 1999 nutrient dynamics of the Black Sea-the Sea of Marmara transect are studied to evaluate the effect of discharges given by deep disposals. Through a one-year study, upper layer nutrient concentrations were generally under the effect of northwestern-shelf Black Sea originated waters. This effect was strictly observed in July, when the upper layer flow was the thickest. On the other hand, partly in November but especially in December the northwestern-shelf Black Sea originated water flow was a minimum resulting in similar concentrations in both layers. Nutrient fluctuations also affected the chlorophyll a and POC concentrations as parameters of productivity. The nutrient concentrations decreased with the effect of spring bloom and highest chlorophyll a values were detected in November at Strait stations that did not match to the Sea of Marmara values. This fact represents the time-scale difference between the Black Sea and the Sea of Marmara. On the contrary, high nutrient concentrations in the lower layer (especially inorganic phosphate), and therefore low N:P ratios reflect the effect of deep discharge. Vertical mixing caused by meteorological conditions of the shallow station (M3) under the effect of surface discharges resulted in homogenous distribution of nutrients. Nutrient concentrations of the stations affected by deep discharge showed that the two-layer stratification of the system did not permit the discharge mix to the upper layer.

Sign in / Sign up

Export Citation Format

Share Document