Blackwater System Research Articles

Conservation of blackwater rivers and streams of the coastal plains of United States: Knowledge and research needs.

Blackwater rivers and streams are a distinct resource type in multiple ecoregions of the United States, including the Coastal Plains. Given the unique nature of blackwaters, they may not be fully protected if using typical water quality standards. Information provided by State agencies was used to identify specific research needs that would directly enhance current assessment approaches. Protection of blackwater rivers and streams would be aided by (1) development of an operational definition; (2) development of a classification framework that distinguishes among blackwater system types; (3) identification of undisturbed or minimally disturbed blackwater systems; (4) identification of stressors that challenge blackwater condition and resilience; and (5) development of criteria that are more suited to the unique conditions of blackwater rivers and streams. Benefits stemming from addressing these research needs may include identification of sites that are unrecognized as impaired and the re-evaluation of sites that may be erroneously listed as impaired when they are not. This would improve reporting by states for Clean Water Act (CWA) Section 305(b) and, for some states, could represent a significant resource savings by reducing the number of sites on CWA Section 303d lists.

Analysis of Suspended Sediment in the Anavilhanas Archipelago, Rio Negro, Amazon Basin

This article analyzes the flows of water and total suspended sediment in different reaches in the lower course of the Negro River, the largest fluvial blackwater system in the world. The area under study is the Anavilhanas Archipelago, which is a complex multichannel reach on the Negro River. Between the years 2016 and 2019, data about water discharge, velocity, and concentration of total suspended solids (TSS) were acquired in sample sections of the Negro River channels located upstream, inside, and downstream of the Anavilhanas Archipelago. In the study area, the Negro River drains an area greater than 700,000 km2, and the mean water discharge observed before the Anavilhanas was about 28.655 m3·s−1, of which 97% flows through two channels of the Archipelago close to the right and left banks. The mean TSS concentration of the Negro River upstream and downstream the Archipelago was 3.28 mg·L−1 and 1.63 mg·L−1, respectively. Within the Archipelago, we observed more TSS in the channel on the left bank of the Negro River (mean of 4.50 mg·L−1). The total suspended sediment discharge of the Negro River before (3.14 Mt·year−1) and after (1.43 Mt·year−1) the Anavilhanas Archipelago indicates a 55% retention of the suspended load due to the low water slope and reduced flow velocity caused by the backwater effect of Solimões River on the Negro River. The hydro-sedimentary scenario of the low course of the Negro River characterized in this study indicates a slow and continuous sedimentation process in the Anavilhanas Archipelago. The results presented will serve as a baseline to assess the impacts of the dams on the Branco River, the main tributary for both water and sediment in the Negro River basin.

Not so pristine – characterising the physico-chemical conditions of an undescribed temporarily open/closed estuary

rapid ecological water requirement study of the Department of Water Affairs in 2009 classified the Goukamma Estuary as largely natural with few modifications, i.e., in an A/B state. However this detailed 13-month study showed that the estuary is impacted. Salinity stratification and hypoxic conditions (dissolved oxygen (DO) < 3 mg·l-1) were measured during both open and closed mouth states. The Goukamma Estuary is a blackwater system and in its natural state is expected to be nutrient poor. However high nutrient concentrations were measured in the middle and upper reaches of the estuary, adjacent to cattle farms. Nutrient concentrations represented mesotrophic (DIN > 500 µg·l-1) to eutrophic conditions (DIP > 25 µg·l-1). Nutrient input stimulated microalgae to attain a high biomass, ranging between 0.3 and 112 µg·l-1 (average 7.7 ± 1.3 µg·l-1) and 0.8 and 289 µg·l-1 (average 21.1 ± 4.4 µg·l-1) during the open and closed mouth states, respectively. Exacerbated by natural salinity stratification which effectively limits oxygenation of the water column, unnaturally high nutrient concentrations, microalgal blooms and coinciding organic loads all indicate poor water quality of the Goukamma Estuary. This research showed that detailed studies involving field measurements of water quality are required before the present health status of an estuary can be assessed.Keywords: Temporarily open/closed estuaries, blackwater system, water quality, stratification, hypoxia, DIN, DIP, microalgae biomass

Differential Expression of Myogenic Regulatory Factor Genes in the Skeletal Muscles of TambaquiColossoma macropomum(Cuvier 1818) from Amazonian Black and Clear Water

Hypothesizing that the Amazonian water system differences would affect the expression of muscle growth-related genes in juvenile tambaqui Colossoma macropomum (Cuvier 1818), this study aimed to analyze the morphometric data and expression of myogenic regulatory factors (MRFs) in the white and red muscle from tambaqui obtained from clear and black Amazonian water systems. All of the MRF transcript levels (myod, myf5, myogenin, and mrf4) were significantly lower in the red muscle from black water fish in comparison to clear water fish. However, in white muscle, only the myod transcript level was significantly decreased in the black water tambaqui. The changes in MRFs gene expression in muscle fibers of tambaqui from black water system provide relevant information about the environmental influence as that of water systems on gene expression of muscle growth related genes in the C. macropomum. Our results showed that the physical and chemical water characteristics change the expression of genes that promote muscle growth, and these results may be also widely applicable to future projects that aim to enhance muscle growth in fish that are of substantial interest to the aquaculture.

Desmídias filamentosas (Conjugatophyceae) de um lago de inundação de águas pretas na Amazônia Central

Com base em 109 amostras coletadas em diferentes fases do ciclo hidrológico nos anos de 2002 a 2004 no lago Cutiuaú, um ambiente de águas pretas localizado no Parque Nacional do Jaú na bacia do rio Negro, foi realizado um levantamento taxonômico das espécies de desmídias filamentosas. Foram identificadas 15 espécies distribuídas em sete gêneros, sendo Desmidium C. Agardh ex Ralfs, com sete espécies, o gênero que apresentou a maior riqueza específica, incluindo D. quadratum citado pela primeira vez para o estado do Amazonas. O gênero Groenbladia Teiling apresentou três espécies, enquanto os gêneros Bambusina Kützing ex Kützing, Hyalotheca Ehrenberg ex Ralfs, Phymatodocis Nordstedt, Spondylosium Brébisson ex Kützing e Teilingia Bourrelly, apresentaram uma única espécie. Em relação aos períodos do ciclo hidrológico, três táxons foram registrados no período de águas baixas, seis no de vazante, oito no de águas altas e 15, ou seja, todos foram observados no período de enchente.

Comparison of Environmental Effects and Resource Consumption for Different Wastewater and Organic Waste Management Systems in a New City Area in Sweden

An analysis of the environmental effects and resource consumption by four systems for management of wastewater and organic household waste in a new city area have been performed, as follows: (1) conventional system complemented with advanced sludge treatment for phosphorus recovery, (2) blackwater system with urine diversion and food waste disposers, (3) blackwater system with food waste disposers and reverse osmosis, and (4) local wastewater treatment plant with nutrient recovery by using reverse osmosis. Substance-flow analysis and energy/exergy calculations were performed by using the software tool URWARE/ORWARE. Emissions were calculated and classified based on the impact categories global warming potential, acidification, and eutrophication, according to ISO 14042 (2000). The analysis also included nutrient recovery (i.e., the potential to use nutrients as a fertilizer). Depending on which aspects are prioritized, different systems can be considered to be the most advantageous.

Wastewater management integrated with farming –an environmental systems analysis of a Swedish country town

Recycling of plant nutrients in sewage products to arable land is considered to be a step towards a more sustainable society. Sewage sludge is the predominant sewage fertiliser product available today, but the use of sewage sludge in agriculture has been questioned as regards hazardous substances. In this respect, blackwater from separating systems seems to better fulfil agricultural requirements regarding fertiliser products. The objective of this paper was to analyse the environmental impact and resource use in a life cycle perspective for three systems, each including both wastewater handling and agricultural production. In the reference system, food waste disposers were installed in houses. Milled food waste and wastewater were treated in a wastewater treatment plant and the sewage sludge was used for producing a soil conditioner. In the sludge utilisation system, food waste from households was composted, wastewater was treated conventionally and sewage sludge was used in oat production. In the blackwater system, toilet water from low-flush toilets and milled organic waste were digested together and spread in growing oats. Data on the wastewater system were derived from simulations by the substance-flow model URWARE/ORWARE. The blackwater system required slightly more primary energy than the other two systems. In particular, construction of storage facilities contributed considerably to energy use. The emissions of greenhouse gases and SO 2 were of the same magnitude for all three systems, while the eutrophying emissions were reduced significantly in the blackwater system. As regards NH 3 and NO X , the emissions were highest for the blackwater system. High substitution of mineral fertiliser, optimal spreading technique and well-designed collection and storage facilities were important factors for the environmental outcome in the blackwater system.

Microsite Influences on Productivity and Nutrient Circulation Within Two Southeastern Floodplain Forests

At broad spatial scales, floodplain forests of the southeastern USA are often perceived as either nutrient poor or nutrient rich. Perceived differences in nutrient availabilities between oligotrophic blackwater and eutrophic redwater floodplain forests suggest rates of aboveground net primary production (ANPP) are lower on the former. However, for these floodplain types, microsite variation may influence relationships between nutrient circulation and ANPP to a greater extent than landscape position and geomorphology of their associated watershed. Therefore, our objectives were to compare ANPP, nutrient circulation through litterfall and decomposition, and the microbial biomass among microsites that differed in terms of soils and hydrology within two riverine floodplain forests. The two floodplains used in this study were located along the Satilla River, a Coastal Plain blackwater system, and the Altamaha River, a Piedmont redwater system, both of which are located in southeastern Georgia. Microsite influences on ANPP were not significantly different during 1999 and 2000 for the Satilla (SAT) and Altamaha (ALT) floodplains. Litterfall production and patterns of P and Ca circulation on the SAT floodplain were significantly lower for the driest microsite type during both years. Microbial biomass N and P were also lowest for the driest microsite, especially in 2000. Overall, microsites on the SAT displayed greater variation in P and Ca cycling than did those of the ALT. Litterfall production, nutrient circulation in litterfall and decomposition, and the microbial biomass were similar among microsites of the ALT floodplain during both years. These findings suggest that spatial variability in nutrient cycling may be greater for oligotrophic floodplain forests.

Competition between biological and photochemical processes in the mineralization of dissolved organic carbon

The photo‐ and bioreactive components of dissolved organic matter (DOM) from three different environments were determined during long‐term decomposition experiments. Terrigenous DOM was collected from a black‐water system, plankton DOM was harvested from phytoplankton cultures, and lake water served as a DOM source with both terrigenous and plankton components. Photomineralization accounted for the removal of 46 and 7% of terrigenous and lake‐dissolved organic carbon (DOC), respectively, while no loss in DOC was observed when plankton DOM was exposed to irradiation. Biomineralization accounted for the removal of 27% each of terrigenous and lake DOC and 74% of plankton DOC. Phototransformations of terrigenous and lake DOM resulted in 7% and 2% increases in biodegradable DOC, respectively, while no increase in biodegradable DOC was observed for irradiated plankton DOM. In two different experimental approaches, terrigenous DOM was exposed to sequential and alternating bio‐ and photodegradation, respectively, to determine the fractions of DOC that were bioreactive and photoreactive. About 15% of terrigenous DOC was susceptible to both biomineralization and photomineralization. These results demonstrate that biological and photochemical processes compete in the mineralization of DOC. Photomineralization of bioreactive DOC is likely an important factor determining the net effect of irradiation on the bioreactivity of DOM.

Karyological, biochemical, and physiological aspects of Callophysus macropterus (Siluriformes, Pimelodidae) from the Solimões and Negro Rivers (central Amazon).

Karyological characteristics, i.e., diploid number, chromosome morphology and nucleolus organizer regions (NORs), biochemical characteristics, i.e., electrophoretic analysis of blood hemoglobin and the tissue enzymes lactate dehydrogenase (LDH), malate dehydrogenase (MDH), alcohol dehydrogenase (ADH), and phosphoglucose isomerase (PGI), and physiological characteristics, i.e., relative concentration of hemoglobin and intraerythrocytic concentrations of organic phosphates were analyzed for the species Callophysus macropterus collected from Marchantaria Island (white water system--Solimões River) and Anavilhanas Archipelago (black water system--Negro River). Karyological and biochemical data did not reveal significant differences between specimens collected at the two sites. However, the relative distribution of hemoglobin bands I and III (I = 16.33 +/- 1.05 and III = 37.20 +/- 1.32 for Marchantaria specimens and I = 6.33 +/- 1.32 and III = 48.05 +/- 1.55 for Anavilhanas specimens) and levels of intraerythrocytic GTP (1.32 +/- 0.16 and 2.76 +/- 0.18 for Marchantaria and Anavilhanas specimens, respectively), but not ATP or total phosphate, were significantly different, indicating a physiological adaptation to the environmental conditions of these habitats. It is suggested that C. macropterus specimens from the two collecting sites belong to a single population, and that they adjusted some physiological characteristics to adapt to local environmental conditions.

Fish–macrophyte relationship in the Anavilhanas Archipelago, a black water system in the Central Amazon

The characin fish fauna associated with floating meadows on the floodplain of the Rio Negro was studied at the beginning of the rising water period. Two microhabitats were identified in the meadows (Paspalum plus Oryza vegetation and pure Oryza vegetation) and their influence on characin abundance tested. No significant difference in characin numbers was found between microhabitats. Three species accounted for 82% of characins captured: Hemigrammus levis, Metynnis cf. hypsauchen and Moenkhausia lepidura. Metynnis cf. hypsauchen was more abundant in Paspalum plus Oryza vegetation than in the other microhabitat. A similar difference was not found for H. levis and M. lepidura. The diets of the three species were similar in the smaller size classes, consisting primarily of Cladocera. However, the diets differed in the larger size classes with M. cf. hypsauchen foraging mainly on filamentous algae, M. lepidura on wild rice and H. levis on Cladocera. The diet shift is apparently an optimal foraging strategy, while the differences in microdistribution appear to be related to predation risk.

The plankton community of an acid blackwater South Carolina power plant impoundment

Robinson Impoundment, an acid blackwater system in the South Carolina sandhills, serves as a cooling pond for a 854 MW power plant. It is divided by a causeway into an upper and lower impoundment. The upper impoundment is narrow, shallow, exhibits higher flow, and much more periphytic and rooted aquatic macrophyte vegetation. The lower impoundment is wide and deep with many sandy shoreline areas and little macrophyte vegetation.

A mathematical deterministic river-quality model. Part 2: Use in evaluating the water-quality management of the blackwater catchment

A deterministic river-quality model has been used to predict river qualities in the Blackwater System (part of the River Thames catchment). It was tested under the relatively dry conditions of 1973 and more normal conditions of 1974, and it was concluded that satisfactory agreement between predicted and observed data was obtained. On this basis, the use of the model was extended to simulate conditions for 1981 and 1991 in an attempt to evaluate what the effect on the river quality would be if certain capital works programmes were or were not proceeded with. It was demonstrated that with the potential expansion in this catchment area, the quality of the Blackwater would not improve unless capital works programmes are carried out.