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Surface water quality and deforestation of the Purus river basin, Brazilian Amazon



In the last years, deforestation constitutes a threat for the aquatic ecosystems. This paper aims to characterize the water quality of the Purus river in the Brazilian Amazon, and investigate the relations between water quality and deforestation of the Purus river basin over a 9-year period, as well as to quantify the Purus river basin’s land cover changes (%) in a 5-year period. Sampling data from upstream to downstream show a decrease in pH-value, dissolved oxygen, electrical conductivity, and total suspended solids. Correlation analysis revealed a significant negative correlation of the accumulated total deforestation values (km2) with the pH-value (in all the study sites), and a significant positive correlation with temperature (only in two sites). However, the deforestation rates (km2/year) did not present, in none of the study stations, any significant correlation with water quality parameters. It seems that the effects of deforestation on water quality are related not with the rate but with the total area deforested. It was estimated that the basin’s forested area decreased by 5.17%. Since similar attributes are common in other basins of the whitewater systems of the Brazilian Amazon, this results may be seen as a warning on the effects of deforestation on water quality (reduction in pH and increment in temperature values), in larger areas than those of our study sites. To maintain the conser- vation and preservation status of the Purus river basin, it is necessary, the implementation of a transboundary watershed management program that could serve as a conservation model for Brazil and other countries of the Amazonian region.
Surface water quality and deforestation of the Purus river
basin, Brazilian Amazon
Eduardo Antonio Rı
´os-Villamizar .Maria T. F. Piedade .
Wolfgang J. Junk .Andre
´a Viviana Waichman
Received: 7 October 2016 / Accepted: 21 November 2016
ÓThe Author(s) 2016. This article is published with open access at
Abstract In the last years, deforestation constitutes a threat for the aquatic ecosystems. This paper aims to
characterize the water quality of the Purus river in the Brazilian Amazon, and investigate the relations between
water quality and deforestation of the Purus river basin over a 9-year period, as well as to quantify the Purus
river basin’s land cover changes (%) in a 5-year period. Sampling data from upstream to downstream show a
decrease in pH-value, dissolved oxygen, electrical conductivity, and total suspended solids. Correlation
analysis revealed a significant negative correlation of the accumulated total deforestation values (km
) with
the pH-value (in all the study sites), and a significant positive correlation with temperature (only in two sites).
However, the deforestation rates (km
/year) did not present, in none of the study stations, any significant
correlation with water quality parameters. It seems that the effects of deforestation on water quality are related
not with the rate but with the total area deforested. It was estimated that the basin’s forested area decreased by
5.17%. Since similar attributes are common in other basins of the whitewater systems of the Brazilian
Amazon, this results may be seen as a warning on the effects of deforestation on water quality (reduction in pH
and increment in temperature values), in larger areas than those of our study sites. To maintain the conser-
vation and preservation status of the Purus river basin, it is necessary, the implementation of a transboundary
watershed management program that could serve as a conservation model for Brazil and other countries of the
Amazonian region.
Keywords Amazon basin Deforestation Purus Water quality
The Amazon, that presents different characteristics among others Brazilian hydrographic areas, is one of the
world’s unique regions containing most of the usable water resources in Brazil. This water potential displays
E. A. Rı
´os-Villamizar (&)M. T. F. Piedade
Instituto Nacional de Pesquisas da Amazo
ˆnia/Ecologia, Monitoramento e Uso Sustenta
´vel de A
´reas U
´midas Amazo
(Grupo MAUA/CDAM/INPA), Campus I, Av. Andre
´jo, 2.936, Petro
´polis, Caixa Postal 478, CEP: 69067-375 Manaus,
W. J. Junk
Instituto Nacional de Cie
ˆncia e Tecnologia em A
´reas U
´midas (INCT-INAU-UFMT), Cuiaba
´, Brazil
A. V. Waichman
Universidade Federal do Amazonas - UFAM/ICB, Manaus, Brazil
Int Aquat Res
DOI 10.1007/s40071-016-0150-1
privileged place into the speeches on Amazonian sustainable development. Water chemistry provides
important parameters for quantifying biogeochemical cycles and determines management options in river
systems and wetlands. The first scientific classification of Amazonian rivers was elaborated by Sioli (1956)
who used water color, transparency, pH and electrical conductivity to explain limnological characteristics of
the large Amazonian rivers and correlated these characteristics to the geological properties of the river
catchments, a landscape ecology approach. Whitewater rivers (such as the Amazon, Jurua
´and Madeira) are
turbid and have their origins in the Andes, from which they transport large amounts of nutrient-rich sediments.
Their waters have near neutral pH and relatively high concentrations of dissolved solids indicated by the
electric conductivity that varies between 40 and 140 lScm
. Blackwater rivers (such as the Negro River)
drain the Precambrian Guiana shield, which is characterized by large areas of white sands (podzols), their
waters show low quantities of suspended matter but high amounts of humic acids that give the water a
brownish-reddish color. The pH values of such rivers are in the range of 4–5 and their electrical conductivity is
\20 lScm
. Clearwater rivers (such as the Tapajo
´s and Xingu rivers) have their upper catchments in the
Cerrado region of the Central Brazilian archaic shield. The transparency of their greenish waters is above
1.5 m, with low amounts of sediments and dissolved solids, electrical conductivity is in the range of
10–20 lScm
, and pH that varies between 6 and 7 in large rivers.
´os-Villamizar et al. (2014) classified a number of rivers using the combination of several parameters such
as alkali (Na, K) and alkali-earth (Ca, Mg) metals, major anions, electrical conductivity, pH, N
, water
color and suspended sediment load to distinguish the three classical water types (white, black and clear) and to
separate other water bodies with intermediate position, concluding that many rivers and streams have to be
considered as mixed waters resulting from the influence of lower order tributaries with different physico-
chemical properties of their waters. According to this classification system, the Purus river is a whitewater
river but many of its tributaries are of intermediate type (Rı
´os-Villamizar et al. in preparation) if considering
that the geology of the pre-Andean zone is rather heterogeneous with large old sedimentation areas (paleo-
varzeas), which sediments are strongly weathered, but still have a higher bioelement content than the tertiary
sediments of the central Amazon basin and the soils on the archaic shields.
The Purus river is one of the chief tributaries of the Solimo
˜es/Amazon River system, being one of the
longest rivers in South America, rising in the eastern lowlands of Peru and flowing about 3380 kilometres (km)
before entering Solimo
˜es river at the northwestern Brazil. The estimated water volume that is generated within
the Purus river basin is about 8500 m
, and the total area of this basin is about 375,458 km
. The Purus
basin is classified into the basin group that still is in a high conservation status in the Brazilian Amazon
(Fig. 1). However, in recent years, the cattle ranching, the advance of the agricultural frontier mainly for
soybean production and the associated deforestation constitute a threat for the aquatic ecosystems.
Materials and methods
The aims of this paper are to diagnose water quality changes at the main channel of the Purus river, and to
relate these with deforestation rates (km
/year) and accumulated total deforestation values (km
) of the Purus
Fig. 1 A section of the middle/lower Purus river basin
Int Aquat Res
basin, over a 9-year period, to detect spatial and temporal relationships, using Spearman’s rank and Pearson
correlation analysis, which were performed using Open Stat 4.0. The time series of data were constituted by
the results of, at least, three samplings per year in each monitoring station. The information on deforestation
(PRODES 2007) was reported by the Brazilian National Institute of Spatial Research (INPE), and the data
regarding to water quality were recorded by the Brazilian National Agency of Water (ANA) (HIDROWEB
2007), see Fig. 2. Water samples were collected in the center of the river channel using acid-washed poly-
ethylene bottles, which were rinsed with the water being collected and the samples were manually collected
beneath the surface and kept cool until the time of analysis. Water samples were filtered through Whatman
GF/F fiberglass filters (0.45 lm). The values of electrical conductivity (lScm
at 25 °C), dissolved oxygen
(mg O
), temperature (°C) and pH were measured in the field (on site). In the laboratory, the values of
turbidity (NTU) and total suspended solids (mg l
) were analyzed. All the analyses were carried out by
standard methods (APHA 2005). The Purus river basin’s land cover changes (%), in a 5-year period, also were
identified (diagnosed) by comparing two maps which used remote sensing and geographical information
systems (GIS) techniques.
Results and discussion
Water quality trends
The waters of the Purus river basin showed characteristics of Amazonian natural waters (Furch and Junk
1997). The electrical conductivity and the total suspended solids decrease from upstream to downstream of the
Purus river, probably explained because of the increase of activities associated with the use of land, such as
deforestation, cattle breeding and agriculture, concentrated in the municipalities of Boca do Acre and La
which are located in the Amazonas State in Brazil. It could be related with four deforestation fronts, corre-
sponding with migratory processes, proceeding from the neighboring Brazilian States (Acre and Rondo
which are stimulated by the agriculture expansion and wood predatory exploration (Sanches et al. 2007).
Nevertheless, it was observed an increase in turbidity from upstream to downstream that would be explained
by the soil loss and sediments transport from all the contribution areas along the basin (Leonardo 2003). This
phenomenon also could be responsible for the slight decrease in dissolved oxygen in the same direction. Since
it would be expected a general decreasing trend for total suspended solids and turbidity, the observed opposite
trend for these two parameters, as well as the increasing trend for turbidity could be explained by possible
measurement inaccuracies of the turbidity meter used. The pH-value decreased from upstream to downstream
and the temperature shows a slight increase in the same direction (Fig. 3). This last trend could be due to the
entrance of acidic blackwater tributaries which may contribute to pH and temperature changes.
Fig. 2 Location of the ANA’s water quality monitoring stations on the Purus river: 1Seringal Caridade (Municipal District of
Boca do Acre); 2Seringal Fortaleza (Municipal District of Pauini); 3La
´brea (Municipal District of La
´brea); 4Aruma
District of Beruri). Classes: green color forest; blue color hydrography
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Relations of the water quality with deforestation variables
Table 1presents the accumulated total deforestation data for the years 2000–2006 and the deforestation rates
for the years 2001–2006, respectively.
The higher deforestation rates were observed in Boca do Acre and La
´brea, with larger total deforested areas
probably related with the access by road to the floodplain areas. The lower rates were observed in Pauini and
Beruri (Aruma
˜) where the access to the floodplain forest by road is almost inexistent. No relation was found
among deforestation rates and the water quality parameters at the four sites. On the other hand, ATD showed
Fig. 3 Average values and standard deviation (SD) of the water quality variables for each monitoring station of the ANA in the
Purus river (1998–2006)
Table 1 Deforestation levels for the municipal districts of the study (PRODES 2007)
Year Boca do Acre Pauini La
´brea Beruri
2000 1165.9 – 146.8 – 1245.1 – 181.4 –
2001 1216.2 50.3 154.7 7.9 1419.8 174.7 189.2 7.8
2002 1319.8 103.6 164.8 10.1 1625.9 206.1 191.7 2.5
2003 1570.6 250.8 177.5 12.7 2083.5 457.6 197.2 5.5
2004 1693.7 123.1 184.5 7.0 2449.5 366.0 200.2 3.0
2005 1747.3 53.6 193.5 9.0 2631.3 181.8 200.9 0.7
2006 1831.9 84.6 201.1 7.6 2910.5 279.2 203.3 2.4
– Not reported
ATD accumulated total deforestation (km
), DR deforestation rate (km
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relationships with water quality mainly in station 3 (La
´brea) where larger ATD values were observed. The
ATD values correlates with changes in temperature in stations 2 and 3, with total suspended solids in station 4,
with dissolved oxygen in station 3, with pH-value in all the four stations, and with turbidity in station 3
(Table 2). It is remarkable, the significant negative relationship between the ATD and pH-value, indicating
that increase in the ATD will contribute to decrease the water pH-value. Comparable pattern was already
obtained in other basins in USA, Brazil, Indonesia and India (Kunkle 1974; Neal et al. 1992; Arceivala and
Asolekar 2006; Hirano et al. 2007). Deforestation likely contributes to increase the concentration of nitrates
(nitrification) in the river water, and the increased hydrogen ions, released through increased nitrification,
cause the water pH-value decrease (Lampert and Sommer 1997; Arceivala and Asolekar 2006). Since
deforestation often causes the loss of soil carbon and a net release of CO
, the increasing deforestation
processes in some parts of the basin may also contribute to the intensification of carbon (CO
) release from
soils, with associated changes in content and composition of this gas on river water, which may result in
alterations on water pH-value (Mizuno and Mori 1970; Wissmar et al. 1981; Goudie 2000; Soulsby et al. 2002;
Hirano et al. 2007; Iyobe and Haraguchi 2008; Lal et al. 2015).
Land use changes
In the Purus river basin, as a whole, the highest percentage of the area is represented by forested land since it
covered 85.8% of the total area in 2007. However, this basin suffered a relative intense process of land use and
changes on the cover composition in the period 2003–2007. Forests were cleared to give way to expansion of
Table 2 Correlation coefficient analysis among DR, ATD and water quality variables in the Purus river basin (2000–2006)
ATD 1 DR 1 ATD 2 DR 2 ATD 3 DR 3 ATD 4 DR 4
Temp1 0.403** 0.216**
pH 1 -0.883* 0.132**
E.C 1 -0.584** -0.326**
Turb 1 -0.417** -0.042**
D.O 1 0.441** 0.356**
TSS 1 -0.011** -0.364**
Temp 2 0.863* 0.035**
pH 2 -0.765* -0.382**
E.C 2 -0.107** -0.543**
Turb 2 -0.631** 0.071**
D.O 2 0.671** -0.219**
TSS 2 0.572** 0.322**
Temp 3 0.793* 0.174**
pH 3 -0.971* -0.430**
E.C 3 -0.433** -0.558**
Turb 3 -0.760* -0.124**
D.O 3 0.941* 0.388**
TSS 3 -0.159** 0.193**
Temp 4 0.511** -0.455**
pH 4 -0.828* 0.598**
E.C 4 -0.284** 0.680**
Turb 4 0.154** 0.399**
D.O 4 -0.259** 0.305**
TSS 4 0.848* -0.506**
1Station 1, 2Station 2; 3Station 3, 4Station 4, Temp temperature (°C), E.C electrical conductivity (lScm
), Turb turbidity
(NTU), D.O dissolved oxygen (mg l
), TSS total suspended solids (mg l
), ATD accumulated total deforestation (km
), DR
deforestation rate (km
* Significant (P\0.05); ** non-significant (P[0.05)
Int Aquat Res
cattle ranching and farming lands on this basin. According to the spatial sequence displayed by the INPE data,
the deforestation rates are further increasing at the municipal districts located at south and southeast of the
Amazon region. In this sense, the larger deforested areas along the basin are concentrated close to urban areas
of the municipal districts of Rio Branco, Sena Madureira, Pla
´cido de Castro and Senador Guiomard, in the
Fig. 4 Comparison of land cover and use maps in the Purus river basin. a2003 (Water Resources eAtlas 2003); b2007 (modified
from Rı
´os-Villamizar et al. 2011)
Int Aquat Res
Acre State; and La
´brea and Boca do Acre, in the Amazonas State (Fig. 4b). It is evident that the reduction of
forest cover was roughly 5.17% in the period 2003–2007 (Fig. 4; Table 3). Another important aspect of the
identified changes is that wetlands area lost approximately 1.1% in the same period, but this variation would
also be due to the effects of the flood pulse, during natural seasonal periods, on the rivers and lakes’ water
level (Junk et al. 1989; Junk and Wantzen 2004).
The analyzed waters of the Purus river basin showed typical characteristics of Amazonian natural waters. We
observed clear trends in changes of physico-chemical properties of water from upstream to downstream of the
Purus river such as decrease in pH-value, dissolved oxygen, electrical conductivity, total suspended solids, and
increase in turbidity. Only the pH-value presented significant negative relationships with the ATD in all the
study sites, indicating that increase in the ATD will contribute to decrease the water pH-value. On the other
hand, the ATD values correlated positively and significantly with changes of temperature only in stations 2
and 3, indicating that increase in the ATD will contribute to increase the water temperature. The DR did not
present, in none of the study stations, any significant relation with the water quality parameters. Then, the
deforestation levels have not yet caused a large effect on the water quality, which is probably most influenced
by hydrological and climatic factors such as river discharge, river level, and pluvial precipitations, among
others; but this will be addressed in forthcoming papers.
It seems that the effects of deforestation on water quality are related not with the rate but with the total area
deforested, and they become apparent after a minimal size of deforested area is achieved.
Therefore, despite the good conservation status for most parts of the Purus river basin, impacts on water
quality caused by human activities are evident, especially close to urban areas, at a local scale. Since similar
attributes are common in other basins of the whitewater systems of the Brazilian Amazon, this may be seen as
a warning on the effects of deforestation on water quality in larger areas than those of our study sites. Actions
to control the deforestation in this basin would need to be taken to maintain its conservation status and, in view
of that, it would be necessary to implement a transboundary watershed management program for conservation
and preservation purposes, and this program could serve as a conservation model for Brazil and other
Amazonian countries.
Acknowledgements This work was funded by Brazilian National Scientific Council (CNPq), Tropical Forest Protection Program
(PPG-7), Grant Number 556899/2005-9. We thank the postgraduate Program of Environmental Sciences and Sustainability in the
Amazon (PPG/CASA/UFAM), the postgraduate Program in Climate and Environment at the National Institute of Amazonian
Research (INPA/UEA), the Ecology, Monitoring and Sustainable Use of Wetlands Group (MAUA/CDAM/INPA), CAPES/
Table 3 Land cover variables percents in the Purus river basin on 2003 and 2007
Land cover variables 2003 (%)
2007 (%)
Urban area 0.1 0.13
Deforested area 6.7
Forest cover 91.0 85.83
Hydrography – 1.6
Wetlands (Va´rzea) 7.0 5.9
Aquatic macrophytes 0.01
Secondary forest 0.89
– Not reported
Water Resources eAtlas (2003) (Basin area: 371,042.0 km
´os-Villamizar et al. (2011) (Basin area: 375,458.5 km
Percent loss of original forest cover
This category includes percent grassland, savanna and shrubland (3.9%), and percent cropland (3.9%)
This category includes cloudy area
Int Aquat Res
CNPq—IEL Nacional—Brasil, Programa de Apoio a
˜o de Doutores no Amazonas (FIXAM/AM) and Programa de Apoio a
˜o em Eventos Cientı
´ficos e Tecnolo
´gicos (PAPE), from the Fundac¸a
˜o de Amparo a
`Pesquisa do Estado do Amazonas
(FAPEAM/SECTI/AM) for financial support. We also thank Kyara Martins Formiga by suggestions and elaboration of the study
area map.
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you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if
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... Several researches have been investigating the removal of natural vegetation in areas of non-indigenous occupation, such as the current area in the Amazon Biome (Ometto et al., 2014;Fearnside et al., 2017). These studies have shown that deforestation triggers significant changes in the hydrological cycle (Vergopolan and Fisher, 2016), for example, the quality of waters and of the aquatic environments (Ríos-Villamizar et al., 2017), on the life of the remaining socio-diversity (Santos, 2018), the rising global and regional average temperature (Prevedello et al., 2019), the intensification of extreme weather events (Boers et al., 2017;Zemp et al., 2017;Leite Filho et al., 2019) and also in the proliferation of infectious diseases and public health (Ellwanger et al., 2020). Thus, according to Nóbrega (2014), the deforestation is the biggest problem in the hydrographic basin of the Amazon River and its impacts can generate several consequences that may affect different geographical scales (local, regional and global). ...
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... Tais alterações na floresta amazônica estão associadas ao processo de uso e ocupação da terra (Shielein; Borner, 2018), decorrente da expansão do agronegócio , da exploração da madeira (Ângelo;Sá, 2007) e da mineração (Sonter et al., 2017), além do avanço da agricultura de subsistência (Maciel et al., 2018). Através dessas atividades humanas, ocorre o desmatamento associado com as mudanças climáticas (Marengo et al., 2018), que modifica padrões de variabilidade e outras componentes ambientais, como o balanço hídrico (Heerspink et al., 2020) e a qualidade da água (Ríos-Villamizar, 2017). Assim, a retirada da cobertura florestal está alterando a temperatura do ar (Prevedello et al., 2019), o que pode resultar no desconforto do bemestar populacional (Wolff et al., 2018). ...
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O aumento das taxas de desmatamento nos últimos anos tem provocado alguns efeitos no clima como a alteração nos padrões de temperatura do ar na Amazônia. O objetivo deste estudo foi avaliar as variações na temperatura do ar, em associação com as taxas de desmatamento em alguns municípios do Estado do Pará, durante as últimas décadas, baseando-se nos padrões de temperatura. Os dados de desmatamento anual, em nível municipal, foram adquiridos do Projeto de Monitoramento do Desmatamento na Amazônia Brasileira por Satélite. A temperatura do ar (TMáx e Tmín) foi obtida do Instituto Nacional de Meteorologia. A análise das informações das variáveis ambientais em estudo foi realizada considerando os anos de 2000 até 2019, comparando os períodos seco e chuvoso. As variáveis ambientais foram inseridas no software GrADS para a confecção das informações espacializadas, com a vizualização da variação temporal da TMáx e Tmín, além do cálculo da correlação. Observa-se que as regiões do leste paraense e a do arco do desmatamento são as mais críticas na relação entre desmatamento e temperatura do ar. Os municípios com maiores índices de desmatamento são Altamira (10.000 km2), Marabá (~7.500 km2), Itaituba (~5.000 km2), Monte Alegre (~5.000 km2), Conceição do Araguaia (~2.500 km2), Óbidos (>2.500 km2) e Porto de Moz (>2.500 km2). Há uma elevação da temperatura do ar e a estatística mostra correlação significativa em alguns desses locais. Alertas para alguns municípios são apontados, referentes ao aumento da temperatura do ar relacionado ao desmatamento, principalmente no período seco.Palavras-chave: Floresta, Clima, Amazônia. Influence of deforestation on air temperature ABSTRACT The increase in deforestation rates in recent years has had some effects on the climate, such as changes in air temperature patterns in the Amazon. The objective of this study was to evaluate variations in air temperature, in association with deforestation rates in some municipalities of the State of Pará, during the last decades, based on temperature patterns. Annual deforestation data, at the municipal level, were acquired from the Satellite Monitoring of Deforestation in the Brazilian Amazon. The air temperature (TMax and Tmin) was obtained from the Instituto Nacional de Meteorologia. The analysis of information from the environmental variables under study was carried out considering the years 2000 to 2019, comparing the dry and rainy periods. The environmental variables were inserted in the GrADS software to create the spatialized information, with the visualization of the temporal variation of TMáx and Tmín, in addition to the calculation of the correlation. It is observed that the regions of eastern Pará and the arc of deforestation are the most critical in the relationship between deforestation and air temperature. The municipalities with the highest deforestation rate are Altamira (10,000 km2), Marabá (~7,500 km2), Itaituba (~5,000 km2), Monte Alegre (~5,000 km2), Conceição do Araguaia (~2,500 km2), Óbidos (>2,500 km2 ) and Port of Moz (>2,500 km2). There’s a rise in air temperature and statistics show a significant correlation in some of these locations. Alerts for some municipalities are pointed out, referring to the increase in air temperature related to deforestation, especially in the dry season.Keywords: Forest, Climate, Amazon.
... Because of its large area, it is compatible with the spatial resolution of RS products (e.g., a pixel of GRACE presents spatial resolution of roughly 300-400 km). Besides, Purus river basin has minor anthropogenic influences (Ríos-Villamizar et al., 2017); also evidenced by the mostly forested last use depicted in Fig. 2b), which simplifies the modeling process. The climate is equatorial (Fig. 2d), and mean annual rainfall is 2147 mm/year (according to in-situ gauges). ...
... The chemical characteristic of river water has attracted great attention all over the world (Peter et al., 2020;Feng et al., 2022). Many studies were concentrated on the famous rivers, such as the Amazon river (Ríos-Villamizar et al., 2017), the Nile (Wael et al., 2021), the Yangtze river (Zhang et al., 2022) and the Yellow river (Lv et al., 2022), etc. Their results were contributed to the protection and conservation of water resources and other natural resources. ...
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Rivers are the main supply sources in inland areas for human activities, but they are also regarded as the most susceptible water bodies to pollutants. Understanding the key factors influencing the chemical characteristic is the basis for water supply and public health concern. And it is helpful for the protection of surface water under the influence of human activities. To reveal the hydrochemical process of river water and the key factors affecting the chemical compositions, a total of 33 samples from rivers in Muling-Xingkai Plain are collected for principal component analysis and hydrochemical analysis. Results indicate that river water is characterized by the type of HCO 3 -Ca and mixed HCO 3 -Ca·Na. But some samples with relative high nitrate content have Cl ⁻ as the dominant anion. The natural sources of chemical ions in river water are silicate and carbonate minerals. The chemical fertilizers only slightly influence the chemical compositions of river water due to the retardation of black soil with weak permeability. The chemical compositions of river water in Muling river are significantly influenced by domestic sewage compared with that in Abuqin river and Qihulin river. The widespread thick black soils play a key roles in protecting the river quality and groundwater quality, and human activities only play a limited roles in determining the river quality in the Muling-Xingkai Plain. At present, the contents of major chemical ions in river water meet the irrigation standard. Although the irrigation with river water do not lead to the food safety issue, the government agencies should adopt adequate measures to control the indiscriminate discharge of domestic sewage and application of fertilizers for preventing the accumulation of pollutants in rivers. This study is beneficial to the efficient management of surface water resources in agricultural areas with similar geological conditions and hydrogeological conditions.
... For example river nitrate concentrations were found to decrease in Panama and Brazil where primary forest was converted to pasture (Deegan et al., 2011;Valiela et al., 2013Valiela et al., , 2014. In contrast, some river water characteristics such as pH do not show a consistent trend with LULC change (Ling et al., 2016;Ríos-Villamizar et al., 2017;Santos and De Paula, 2019;Tanaka et al., 2021), and underlying geology may be a more important factor in these cases (Young et al., 2005). ...
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Land use and land cover (LULC) can significantly alter river water, which can in turn have important impacts on downstream coastal ecosystems by delivering nutrients that promote marine eutrophication and hypoxia. Well-documented in temperate systems, less is known about the way land cover relates to water quality in low-lying coastal zones in the tropics. Here we evaluate the catchment LULC and the physical and chemical characteristics of six rivers that contribute flow into a seasonally hypoxic tropical bay in Bocas del Toro, Panama. From July 2019 to March 2020, we routinely surveyed eight physical and chemical characteristics (temperature, specific conductivity, salinity, pH, dissolved oxygen (DO), nitrate and nitrite, ammonium, and phosphate). Our goals were to determine how these physical and chemical characteristics of the rivers reflect the LULC, to compare the water quality of the focal rivers to rivers across Panama, and to discuss the potential impacts of river discharge in the Bay. Overall, we found that the six focal rivers have significantly different river water characteristics that can be linked to catchment LULC and that water quality of rivers 10 s of kilometers apart could differ drastically. Two focal catchments dominated by pristine peat swamp vegetation in San San Pond Sak, showed characteristics typical of blackwater rivers, with low pH, dissolved oxygen, and nutrients. The remaining four catchments were largely mountainous with >50% forest cover. In these rivers, variation in nutrient concentrations were associated with percent urbanization. Comparisons across Panamanian rivers covered in a national survey to our focal rivers shows that saltwater intrusions and low DO of coastal swamp rivers may result in their classification by a standardized water quality index as having slightly contaminated water quality, despite this being their natural state. Examination of deforestation over the last 20 years, show that changes were <10% in the focal catchments, were larger in the small mountainous catchments and suggest that in the past 20 years the physical and chemical characteristics of river water that contributes to Almirante Bay may have shifted slightly in response to these moderate land use changes. (See supplementary information for Spanish-language abstract).
... Turbidity showed a high increase from headwaters to lower reaches (0.28-2.48 mg/L). These results are typical of basins with high levels of agriculture and livestock near river banks as the case of the MRB, since these activities stimulate erosion and sediment transport along the basin (Kosmowska et al., 2016;Margenat et al., 2017;Ríos--Villamizar et al., 2017). Finally, microbiological parameters showed levels above the established threshold in Ecuadorian and American water quality regulation ( Fig. 2; Table S3). ...
Degradation of freshwater ecosystems by uncontrolled human activities is a growing concern in the tropics. In this regard, we aimed at testing an integrative framework based on the IFEQ index to assess freshwater ecosystem health of river basins impacted by intense livestock and agricultural activities, using the Muchacho River Basin (MRB) as a case study. The IFEQ combines multiple lines of evidence such as riverine hydromorphological analysis (LOE 1), physicochemical characterization using ions and pesticides (LOE 2), aquatic macroinvertebrate monitoring (LOE 3), and phytotoxicological essays with L. sativa (LOE 4). Overall, results showed an important reduction in streamflow and an elevated increase in ion concentrations along the MRB caused by deforestation and erosion linked to agricultural and livestock activities. Impacts of the high ion concentrations were evidenced in macroinvertebrate communities as pollution-tolerant families, associated with high conductivity levels, represented 92 % of the total abundance. Pollution produced by organophosphate pesticides (OPP) was critical in the whole MRB, showing levels that exceeded 270-fold maximum threshold for malathion and 30-fold for parathion, the latter banned in Ecuador. OPP concentrations were related to low germination percentages of L. sativa in sediment phytotoxicity tests. The IEFQ index ranged from 44.4 to 25.6, indicating that freshwater ecosystem conditions were “bad” at the headwaters of the MRB and “critical” along the lowest reaches. Our results show strong evidence that intense agricultural and livestock activities generated significant impacts on the aquatic ecosystem of the MRB. This integrative approach better explains the cumulative effects of human impacts, and should be replicated in other basins with similar conditions to help decision-makers and concerned inhabitants generate adequate policies and strategies to mitigate the degradation of freshwater ecosystems.
The goal of this work was to perform preliminary surveys over the abiotic factors of Roosevelt river, Amazonas, Brazil in four different periods: rising, flood, lowing, and dry. Four sites were monitored: P1, P2, P3 and P4. There were measured: depth, water transparency, conductivity, pH, surface water temperature and dissolved oxygen. Results showed a seasonality at the four sampling stations. The conductivity always showed high values in the flood at all sampling stations, except for P4. The pH showed low variation in all periods and sampling stations. Only depth and transparency were significant in P2. We conclude that studies are required that indicate the potential causes of conductivity variation: autochthonous or human activities. The explanation of the conductivity source is necessary since the studied area is located near a conservation area.
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South America is home to more miniature fishes (<26 mm in standard length) than any other continent. Despite this diversity, the ecology of miniature fishes is poorly studied. To promote the study of miniature fish ecology, we investigated patterns in total richness, assemblage structure and environmental correlates for miniature fishes in the rio Jacundá drainage of the Lower Amazon River basin, Pará State. Based on multi-pass dip-netting of leaf litter at 20 locations distributed across two sites, we collected miniature species and used rarefaction to estimate 9 to 14 species might be present. The miniature fish assemblage at the upstream site was a nested subset of the downstream site, and water pH and canopy cover, two features known to be altered by deforestation, correlated most strongly with assemblage variation. Our work represents one of the first quantitative assessments of environmental correlates with miniature fish assemblages and highlights research topics that should be investigated further to promote conservation and preservation of the overlooked and understudied Amazonian diminutive freshwater fish fauna.
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Abstract JUNK, W. J., P. B. BAYLEY, AND R. E. SPARKS, 1989. The flood pulse concept in river-floodplain systems, p. 110-127. In D. P. Dodge [ed.] Proceedings of the International Large River Symposium. Can. Spec. Publ. Fish. Aquat. Sci. 106. The principal driving force responsible for the existence, productivity, and interactions of the major biota in river—floodplain systems is the flood pulse. A spectrum of geomorphological and hydrological conditions produces flood pulses, which range from unpredictable to predictable and from short to long duration. Short and generally unpredictable pulses occur in low-order streams or heavily modified systems with floodplains that have been leveed and drained by man. Because low-order stream pulses are brief and unpredictable, organisms have limited adaptations for directly utilizing the aquatic/terrestrial transition zone (ATTZ), although aquatic organisms benefit indirectly from transport of resources into the lotic environment. Conversely, a predictable pulse of long duration engenders organismic • adaptations and strategies that efficiently utilize attributes of the ATTZ. This pulse is coupled with a dynamic edge effect, which extends a "moving littoral" throughout the ATTZ. The moving littoral prevents prolonged stagnation and allows rapid recycling of organic matter and nutrients, thereby resulting in high productivity. Primary production associated with the ATTZ is much higher than that of permanent water bodies in unmodified systems. Fish yields and production are strongly related to the extent of accessible floodplain, whereas the main river is used as a migration route by most of the fishes. In temperate regions, light and/or temperature variations may modify the effects of the pulse, and anthropogenic influences on the flood pulse or floodplain frequently limit production. A local floodplain, however, can develop by sedimentation in a river stretch modified by a low head dam. Borders of slowly flowing rivers turn into floodplain habitats, becoming separated from the main channel by levées. The flood pulse is a "batch" process and is distinct from concepts that emphasize the continuous processes in flowing water environments, such as the river continuum concept. Flooclplains are distinct because they do not depend on upstream processing inefficiencies of organic matter, although their nutrient pool is influenced by periodic lateral exchange of water and sediments with the main channel. The pulse concept is distinct because the position of a floodplain within the river network is not a primary determinant of the processes that occur. The pulse concept requires an approach other than the traditional limnological paradigms used in lotic or lentic systems. Résumé JUNK, W. J., P. B. BAYLEY, AND R. E. SPARKS. 1989. The flood pulse concept in river-floodplain systems, p. 110-127. In D. P. Dodge [cd.] Proceedings of the International Large River Symposium. Can. Spec. Publ. Fish. Aquat. Sci . 106. Les inondations occasionnées par la crue des eaux dans les systèmes cours d'eau-plaines inondables constituent le principal facteur qui détermine la nature et la productivité du biote dominant de même que les interactions existant entre les organismes biotiques et entre ceux-ci et leur environnement. Ces crues passagères, dont la durée et la prévisibilité sont variables, sont produites par un ensemble de facteurs géomorphologiques et hydrologiques. Les crues de courte durée, généralement imprévisibles, surviennent dans les réseaux hydrographiques peu ramifiées ou dans les réseaux qui ont connu des transformations importantes suite à l'endiguement et au drainage des plaines inondables par l'homme. Comme les crues survenant dans les réseaux hydrographiques d'ordre inférieur sont brèves et imprévisibles, les adaptations des organismes vivants sont limitées en ce qui a trait à l'exploitation des ressources de la zone de transition existant entre le milieu aquatique et le milieu terrestre (ATTZ), bien que les organismes aquatiques profitent indirectement des éléments transportés dans le milieu lotique. Inversement, une crue prévisible de longue durée favorise le développement d'adaptations et de stratégies qui permettent aux organismes d'exploiter efficacement 1 'ATTZ. Une telle crue s'accompagne d'un effet de bordure dynamique qui fait en sorte que l'ATTZ devient un « littoral mobile'<. Dans ces circonstances, il n'y a pas de stagnation prolongée et le recyclage de la matière organique et des substances nutritives se fait rapidement, ce qui donne lieu à une productivité élevée. La production primaire dans l'ATTZ est beaucoup plus élevée que celle des masses d'eau permanentes dans les réseaux hydrographiques non modifiés. Le rendement et la production de poissons sont étroitement reliés à l'étendue de la plaine inondable, tandis que le cours normal de la rivière est utilisé comme voie de migration par la plupart des poissons.
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The flood pulse concept (FPC), published in 1989, was based on the scientific experience of the authors and published data worldwide. Since then, knowledge on floodplains has increased considerably, creating a large database for testing the predictions of the concept. The FPC has proved to be an integrative approach for studying highly diverse and complex ecological processes in river-floodplain systems; however, the concept has been modified, extended and restricted by several authors. Major advances have been achieved through detailed studies on the effects of hydrology and hydrochemistry, climate, paleoclimate, biogeography, biodiversity and landscape ecology and also through wetland restoration and sustainable management of flood-plains in different latitudes and continents. Discussions on floodplain ecology and management are greatly influenced by data obtained on flow pulses and connectivity, the Riverine Productivity Model and the Multiple Use Concept. This paper summarizes the predictions of the FPC, evaluates their value in the light of recent data and new concepts and discusses further developments in floodplain theory.
The different water colors of Amazonian rivers are documented in the river names e.g., Rio Negro (black river), Rio Branco (white river), Rio Claro (clear river), Rio Verde (green river), and indicate differences in water quality. Sioli (1950) related water color to specific conditions in the catchment areas and recognized three main water types based on water color, load of suspended solids, pH, and load of dissolved minerals, indicated by the specific conductance.
The adverse effects of climate change on agricultural productivity have been evident for several years. Factoring climate change risks into critical decision-making is crucial for ensuring food security. Zambia has adopted conservation agriculture in response to two real threats to food security: loss of animal draught power due to livestock disease, and poor yield and occasional total crop failure due to frequent drought. The main threats from climate change arise from the stresses and shocks caused by high temperature and erratic rainfall, such as shorter growing seasons and water deficit in the soil profile. Under these conditions, conventional tillage practices and a few of the current cropping systems have proved inappropriate and inadequate for sustaining high crop yields. For instance, the national long-term average yield of maize under conventional agricultural practices has declined by 40 %. In this paper, I discuss conservation tillage (CT), soil quality management, and crop and cultivar options for adapting to and mitigating the adverse effects of climate change with the aim of ensuring stable yields. In drought years, employing CT involving deep ripping (15–30 cm), leaving crop residues on the soil surface, and using an appropriate maturity cultivar have consistently resulted in yield increases of 30–70 % (with maize showing the highest yield increase) compared with conventional practices. Early planting is an important factor, and 45 % of the yield increment could be attributed to it. Both physical (plow pans) and chemical (subsoil acidity) impediments to soil depth can greatly restrict root growth into the subsoil and severely restrict the volume of soil exploited and, in turn, the quantities of nutrients and water available to the crop. This investigation shows that adopting a technology package of appropriate culture practices, and seed and crop management can potentially reduce the negative effects of drought and stabilize crop yields.
Large-scale events such as flooding can have a major impact upon the cycling of carbon and nutrients in these aquatic ecosystems. During high water, the major factors influencing primary production appeared to be nutrient concentrations in the mouthbays and varzea (floodplain) lakes and high levels of suspended matter in the Amazon mainstem. In riverine systems, plankton primary production (PPP) averaged 4.04 mg C m-3h-1, and measures of respiration (Re) averaged 0.67 mg C m-3h-1. In the more productive varzea lakes and mouthbays, PPP averaged 26.37 mg C m-3h-1 and Re averaged 2.30 mg C m-3h-1. Bacterial densities, 14C-acetate rate constants for uptake, and plankton carbon: ATP ratios implied that heterotrophic microbiota were important components of the plankton communities in riverine waters. The importance of terrestrial organics to metabolic activity in all waters was implied by high particulate carbon:nitrogen ratios (20:1). -from Authors
Tropical peatlands, which coexist with swamp forests, have accumulated vast amounts of carbon as soil organic matter. Since the 1970s, however, deforestation and drainage have progressed on an enormous scale. In addition, El Niño and Southern Oscillation (ENSO) drought and large-scale fires, which grow larger under the drought condition, are accelerating peatland devastation. That devastation enhances decomposition of soil organic matter and increases the carbon release to the atmosphere as CO2. This phenomenon suggests that tropical peatlands have already become a large CO2 source, but related quantitative information is limited. Therefore, we evaluated the CO2 balance of a tropical peat swamp forest in Central Kalimantan, Indonesia, using 3 years of CO2 fluxes measured using the eddy covariance technique from 2002 through 2004. The forest was disturbed by drainage; consequently, groundwater level (GL) was reduced. The net ecosystem CO2 production (NEP) measurements showed seasonal variation, which was slightly positive or almost zero in the early dry season, and most-negative late in the dry season or early the rainy season. This seasonality is attributable to the seasonal pattern of climate, tree phenology and fires. Slightly positive NEP resulted from smaller ecosystem respiration (RE) and larger gross primary production (GPP) under conditions of high photosynthetic photon flux density (PPFD) and large leaf area index (LAI). The most-negative NEP resulted from smaller GPP and larger RE. The smaller GPP was related to high vapor pressure deficit (VPD), small LAI and low PPFD because of smoke from fires. The larger RE was related to low GL. Annual NEP values were estimated respectively as −602, −382 and −313 g C m−2 yr−1 for 2002, 2003 and 2004. These negative NEP values show that the tropical peat swamp forest, disturbed by drainage, functioned as a CO2 source. That source intensity was highest in 2002, an ENSO year, mainly because of low PPFD caused by dense smoke emitted from large fires.
The preliminary research in some tropical inland waters of Asia is described and suggestions made concerning Phase II of this project undertaken by the International Biological Programme/ Section PF (Freshwater Productivity). Environmental factors were measured in some of the main lakes and rivers and samples taken of the plant and animal life. The stomach contents of over 80 species of fish were examined and the remains of plants and animals present compared with the numbers present in the environment as obtained by the usual hydrobiological netting techniques. Some of the important problems associated with the biological productivity of these waters is discussed in the light of the results obtained from this preliminary survey.