Chemical Water Quality Variables Research Articles

Water quality parameters and nutrient status of selected reservoirs in Tamil Nadu, India

The present study was undertaken to assess the interrelation between water quality and nutrient status of three reservoirssituated in Tamil Nadu, India. These three reservoirs are managed by the Public Works Department (PWD) with the fisheriesaspects falling under the purview of Tamil Nadu State Fisheries Department. In each reservoir, inflow and outflow sectionswere identified as sampling sites. A total of six sampling sites were fixed and monthly sampling for water and fish wasconducted during the period from October 2019 to June 2020. The various physico-chemical parameters such as temperature,electrical conductivity (EC), total dissolved solids (TDS), total suspended solids (TSS), total volatile solids (TVS), turbidity,DO, pH, alkalinity, hardness, chloride, sulphate, biological oxygen demand (BOD) and chemical oxygen demand (COD)were analysed. Biological parameters like chlorophyll-a and primary production as well as various nutrient parameterswere also analysed in the collected water samples. All the physical and chemical water quality variables showed significantvariation (p<0.05) in their concentrations within various months and between stations. All the water quality parameters wereobserved to be within the prescribed limits. The results indicated under-exploitation of fishes from the reservoirs and suggestways to improve fish yields and livelihood of local fisher community. Keywords: Fish catch, Nutrients, Reservoir, Water quality

Impacts of Decommissioning and Upgrading Urban Wastewater Treatment Plants on the Water Quality in a Shellfish Farming Coastal Lagoon (Ria Formosa, South Portugal)

Jacob, J.; Correia, C.; Torres, A.F.; Xufre, G.; Matos, A.; Ferreira, C.; Reis, M.P.; Caetano, S.; Freitas, C.S.; Barbosa, A.B., and Cravo, A., 2020. Impacts of decommissioning and upgrading urban wastewater treatment plants on the water quality in a shellfish farming coastal lagoon (Ria Formosa, South Portugal). In: Malvarez, G. and Navas, F. (eds.), Global Coastal Issues of 2020. Journal of Coastal Research, Special Issue No. 95, pp. 45–50. Coconut Creek (Florida), ISSN 0749-0208.Ria Formosa is a productive coastal lagoon, located on the south coast of Portugal, and represents the largest national producer of shellfish bivalves (ca. 90% production). This ecosystem is subjected to various anthropogenic pressures, including the discharge of urban wastewater treatment plants (UWWTP), which impacts the lagoon water quality. This study aimed to assess the impact of alterations in the functioning of two UWWTP on the water quality of Ria Formosa, based on chemical variables, phytoplankton composition (including potential harmful species) and faecal contamination. During the period September 2018 - October 2019, water sampling was conducted along dominant longitudinal gradients of the effluent dispersion from the discharge point (1-2 km), for two sites: a decommissioned (OP) and a modified (FO) UWWTP. After modification, the later started receiving a higher influent volume (ca. 40%), under an innovative technology system (biological treatment in aerobic granular sludge). Based on chemical water quality variables, phytoplankton and indicators of faecal contamination, a significant improvement along the longitudinal gradient from the discharge point was observed after OP decommissioning. This improvement was fast, being detected two months after decommissioning, positively affecting areas used as shellfish farming grounds. However, distribution patterns of bacteriological indicators and regular shellfish harvesting interdictions suggested an alternative source of faecal contamination after OP decommissioning. At FO, both chemical variables and bacteriological indicators of faecal contamination revealed a slower improvement, only six-months after the UWWTP alteration. Before that, increased and highly variable ammonium, chlorophyll a concentration, phytoplankton abundances and Escherichia coli densities, revealed an unstable phase. Overall, a lower water quality at FO in respect to OP reflected not only a higher effluent volume but also more restricted water circulation for the former.

Cryptosporidium genotyping and land use mapping for hazard identification and source tracking in a small mixed rural-urban watershed in Southeastern Brazil.

Abstract Cryptosporidium, faecal indicator organisms and physical and chemical water quality variables were monitored in a small mixed rural–urban watershed in southeastern Brazil. Cryptosporidium was present in 43% of 117 water samples analysed by microscopy. Concentrations varied from non-detects to 14 oocysts L−1. All samples were further analysed by nested-PCR, and Cryptosporidium spp. were detected in 24% (28) of them. Sequencing at the 18S rRNA locus gave high quality sequences in eight samples, revealing the presence of Cryptosporidium parvum. Cryptosporidium was not correlated with faecal indicator organisms (total coliforms, Escherichia coli, Enterococcus and coliphages), nor with physical and chemical water quality variables (e.g. turbidity, electrical conductivity and chemical oxygen demand), but it was with farm animal density (number of animals per ha). Land use mapping reinforced the suggestions from Cryptosporidium genotyping that both animals (livestock) and humans are potential sources to environmental contamination with oocysts within the watershed.

Threshold Responses of Macroinvertebrate Communities to Stream Velocity in Relation to Hydropower Dam: A Case Study from The Guayas River Basin (Ecuador)

The Guayas River basin is one of the most important water resources in Ecuador, but the expansion of human activities has led to a degraded water quality. The purpose of this study was (1) to explore the importance of physical-chemical variables in structuring the macroinvertebrate communities and (2) to determine if the thresholds in stream velocity related to macroinvertebrate community composition could be identified in the Guayas River basin. Thus, macroinvertebrates and physical–chemical water quality variables were sampled at 120 locations during the dry season of 2013 in the Guayas River basin. Canonical correspondence analysis (CCA) was performed to identify relevant physical–chemical characteristics of the river influencing the distribution of the macroinvertebrate communities. Threshold indicator taxa analysis (TITAN) was used to discriminate between the macroinvertebrate community related to stagnant waters (Daule–Peripa reservoir) and to running waters. CCA indicates that the most important environmental factors influencing the distribution of macroinvertebrate communities were stream velocity, chlorophyll concentration, conductivity, temperature and elevation. Tipping points for the macroinvertebrate community were defined by stream velocity at 0.03 m/s and 0.4 m/s, i.e., stagnant-water (including dam-related reservoirs) taxa start to quickly decrease in abundance and frequency at 0.03 m/s while running-water taxa start to quickly increase in abundance and frequency at 0.03 m/s until a stream velocity of 0.4 m/s. The results provide essential information to define environmental flows to further support water management plans of the Guayas River basin. Information obtained will be useful for management of similar rivers in South America, as well as the rest of the world.

Land use impacts on river health of Uma Oya, Sri Lanka: implications of spatial scales.

Human actions on landscapes are a principal threat to the ecological integrity of river ecosystems worldwide. Tropical landscapes have been poorly investigated in terms of the impact of catchment land cover alteration on water quality and biotic indices in comparison to temperate landscapes. Effects of land cover in the catchment at two spatial scales (catchment and site) on stream physical habitat quality, water quality, macroinvertebrate indices and community composition were evaluated for Uma Oya catchment in the upper Mahaweli watershed, Sri Lanka. The relationship between spatial arrangement of land cover in the catchment and water quality, macroinvertebrate indices and community composition was examined using univariate and multivariate approaches. Results indicate that chemical water quality variables such as conductivity and total dissolved solids are mostly governed by the land cover at broader spatial scales such as catchment scale. Shannon diversity index was also affected by catchment scale forest cover. In stream habitat features, nutrients such as N-NO3-, macroinvertebrate family richness, %shredders and macroinvertebrate community assemblages were predominantly influenced by the extent of land cover at 200m site scale suggesting that local riparian forest cover is important in structuring macroinvertebrate communities. Thus, this study emphasizes the importance of services provided by forest cover at catchment and site scale in enhancing resilience of stream ecosystems to natural forces and human actions. Findings suggest that land cover disturbance effects on stream ecosystem health could be predicted when appropriate spatial arrangement of land cover is considered and has widespread application in the management of tropical river catchments.

Dextrose as carbon source in the culture of Litopenaeus vannamei (Boone, 1931) in a zero exchange system

This work compared the use of dextrose and molasses as carbon sources for biofloc development, water quality maintenance, microorganism composition and growth performance of Litopenaeus vannamei juveniles in biofloc technology (BFT). Two treatments, dextrose and molasses, were tested with four replicates each. Carbon was added to achieve a C:N-AT (N-(NH3+NH4+)) ratio of 6:1. Physical and chemical water quality variables were monitored daily, and shrimp growth was estimated through periodic biometry. After 30 days, survival, final biomass, and feeding conversion rate (FCR) were determined. Dissolved organic carbon, chlorophyll-a, floc volume, total ammonia, nitrite, nitrate and phosphate concentrations, and microorganisms (qualified by groups), were measured every three days. Water quality variables remained within acceptable levels throughout the experimental period, except for nitrite, which reached higher levels than recommended for this species. The use of dextrose resulted in higher water transparency, which influenced the remaining centric diatoms. A superior shrimp performance was observed at this treatment, presumably because of variations on the microbial community. Therefore, it is concluded that the addition of dextrose results in a superior growth performance of L. vannamei when cultured in BFT systems.

Pre treatment of Duckweed Biomass, Obtained from Wastewater Treatment Ponds, for Biogas Production

Considering the capacity of duckweed to treat wastewater and to produce valuable biomass, the present study aimed to highlight the potential of duckweed biomass harvested from wastewater treatment plant for biogas (methane) production. In this way a pilot system, comprising an anaerobic pretreatment and two duckweed ponds designed in series (10 m2 each), was operated with real domestic sewage. The treatment efficiency was evaluated through the monitoring of conventional physical–chemical water quality variables sach as Temperature, pH, total phosphorus (TP), phosphate (PO4), total nitrogen (TN), ammoniacal nitrogen (\(\text{NH}_{4}^{+}\)–N) and chemical oxygen demand (COD). Simultaneously the excess of biomass produced during the treatment was submitted to Biochemical Methane Potential test (BMP) carried out in a multi-batch reactor system. Three pretreatment approaches (fermentative, drying and alkaline) were performed in triplicate to evaluate their influence on methane production. Findings showed that the duckweed ponds removed the organic matter and nutrients from the wastewater (TN = 94%, TP = 92% and COD = 91%). Moreover, the biomass submitted to a fermentative pretreatment returned higher gas production (0.39 Nm³biogas/kgVSfed) compared with the anaerobic digestion (AD) of unpretreated biomass (0.25 Nm³biogas/kgVSfed). These results highlight the potential of duckweed ponds technologies to treat wastewater and produce clean energy simultaneously.

In-stream water quality, invertebrate and fish community health across a gradient of dairy farming prevalence in a New Zealand river catchment

Dairying is an intensive form of agriculture influencing stream ecosystems worldwide via increased levels of nutrients, deposited fine sediment and other contaminants. However, it is not fully understood how dairy farming affects food supply for stream fish. We investigated relationships between dairy farming prevalence in the catchments of nine tributaries of a New Zealand river (0% to 79% of the catchment area) and fish and invertebrate communities. Streams were sampled four times at monthly intervals for brown trout density, fitness/growth-related trout response variables, native fish density, invertebrate community metrics as well as physical and chemical water quality variables. Densities of both brown trout and native fish declined as dairying increased, with no trout found in streams where dairy farms covered more than 50% of the catchment area. Increasing dairy farming prevalence was also associated with higher in-stream levels of dissolved nutrients and deposited fine sediment. These findings suggest that increasing the extent of dairy farming in New Zealand based on practices at the time of sampling results in less abundant and diverse fish communities.

Landscape composition as a determinant of diversity and functional feeding groups of aquatic macroinvertebrates in southern rivers of the Araucania, Chile

Changes in land use which directly or indirectly affect freshwater fauna constitute one of the principal anthropic factors which have caused world biological diversity to disappear rapidly during recent decades. This fauna includes aquatic benthic macroinvertebrates, organisms presenting temporal and spatial variation due to a variety of factors, one of which is the diverse food resources available in the rivers. To assess the effect of anthropic activities on this fauna, the distribution, abundance and characterisation of the functional feeding groups of aquatic macroinvertebrates were analysed, together with the physical and chemical variables in the environments of four coastal river basins of southern south-central Chile. A total of 104 taxa of macroinvertebrates were recorded, the principal component of the community being the Diptera (26 taxa). The abundance and richness of taxa were greater in summer and lower in winter. The most abundant species belong to the order Ephemeroptera and Plecoptera. Macroinvertebrates were affected by different land use: stations with less anthropic activity and greater altitude had higher macroinvertebrates abundance, while the lowest abundance was found at the lowest stations. The functional feeding groups which were most abundant spatially and temporally were the collector-gatherers and the shredders. The physical and chemical water quality variables proved to be of exceptional quality in all the stations. These results suggest that policies governing changes in land use in central and southern Chile should take into account the dramatic alterations that these changes impose on the macroinvertebrates community. Policies for biodiversity conservation should therefore focus on these small but important organisms in the north Patagonian region of South America, which is a hotspot of world diversity.

Characterization of the Microcystis Bloom and Its Nitrogen Supply in San Francisco Estuary Using Stable Isotopes

A suite of particulate and dissolved organic and inorganic stable isotopes were needed to determine the source of the nutrients and cells that initiate and sustain the toxic cyanobacteria bloom of Microcystis in San Francisco Estuary. Particulate and dissolved inorganic and organic matter in water and plankton samples were collected biweekly during Microcystis blooms in 2007 and 2008. Stable isotopes for particulate and dissolved organic matter, nitrate, and water (POM-δ 13C, POM-δ 15N, DOC-δ 13C, C/N ratio, NO3-δ 15N, NO3-δ 18O, H2O-δ 18O and H2O-δ 2H) were compared with Microcystis cell abundance, dissolved organic carbon, chlorophyll a, and toxic total microcystins concentration, as well as physical and chemical water quality variables, including streamflow. The isotopic composition of particulate organic matter, nitrate, and water differed for the Sacramento and San Joaquin Rivers and varied along the salinity gradient. The variation of particulate organic matter and water isotopes suggested Microcystis primarily entered the estuary from the San Joaquin and Old Rivers, where it was most abundant. Nitrate isotopes along with streamflow variables indicated that the San Joaquin River was a source of nitrate to the estuary. However, stable isotope comparison of the nitrogen in Microcystis cells with the dissolved inorganic nitrate in the San Joaquin River indicated that nitrate was not the primary source of nitrogen that supported the bloom. Instead, ammonium from the Sacramento River was the likely sole source of the nitrogen for most of the bloom. Selective uptake of ammonium may have further contributed to the magnitude of the Microcystis bloom which increased with the percent of ammonium within the total dissolved inorganic nitrogen pool.

The application and testing of diatom-based indices in the Vaal and Wilge Rivers, South Africa

Chemical monitoring of water resources is time-consuming and comparatively expensive and may not always provide a composite reflection of actual water quality. Biotic indices using faunal elements, such as macroinvertebrates and fish, are already in place in South Africa as part of the National Biomonitoring Programme for Aquatic Ecosystems (NBPAE). As yet periphyton communities are not included in this programme due to perceived difficulties in the application of these methods. Diatom samples were collected from 10 sites in the Vaal and Wilge Rivers for a period of one year. Diatom cells from these communities were enumerated and diatom-based indices were calculated using OMNIDIA v.3. Diatom index scores were correlated to physical and chemical water quality variables over different time periods and at different concentrations. It was found that the tested diatom indices in general have the best correlation with average chemical data for a one-month period, starting six weeks prior to biological sampling. The Biological Diatom Index showed the strongest relationship to general water quality, while the Eutrophication and Pollution Index showed the strongest relationship to dissolved inorganic phosphorus. Results of correlation analyses obtained in South Africa were comparable to those obtained in several European studies. Hence, it is concluded that diatom-based indices, if implemented in South Africa, will provide a valuable addition to South Africa's suite of tools for the biological monitoring of water quality.

Long-term recovery of macroinvertebrate biota in grossly polluted streams: Re-colonisation as a constraint to ecological quality

To meet targets imposed by the European Water Framework Directive (2000/60/EC) it is vital that measures to improve the status of rivers are both effective and economically viable. Achievement of such aims needs robust understanding of biological responses to changes in water quality vis-a-vis mechanisms of and constraints to the colonization of previously polluted sites. This study therefore examined the long-term chemical and biological changes in historically polluted rivers to elucidate the responses of macroinvertebrate biota to improvements in chemical water quality. For three historically polluted sites in the English Midlands, data from surveys over a period of ca. 50 years were analysed. Ammonia (NH3) and 5-day biochemical oxygen demand (BOD5) were used as chemical water quality indicators. Variations in the ecological recovery of the study sites were assessed using an average pollution sensitivity score (Average Score Per Taxon) and the number of taxa present (usually to family level) present in hand-net samples. Ecological recovery varied widely and was influenced by the intensity and spatial extent of the pollution and the proximity of available sources of potential colonisers. At the site most isolated from potential sources of colonizing taxa, no clean-water macroinvertebrate taxa were recorded 30 years after the major sources of pollution ceased. Where clean-water colonisers were more readily available, significant improvements in ecological quality followed within 2–5 years of the improvements in chemical quality. Macroinvertebrate communities and hence monitoring data may thus be indicative of long past conditions or of biological isolation rather than contemporaneous chemical conditions. Combined chemical and biological data were used to explore a generic model for predicting recovery rates and success. Neither BOD5 nor NH3 were found to provide a consistent and meaningful prediction of either average pollution tolerance of macroinvertebrate taxa or of the number of taxa present. Long-term relationships between macroinvertebrate variables and chemical water quality variables, however, were non-linear, suggesting that water quality thresholds may have to be exceeded before biological recovery can occur. Even when chemical water quality has been improved substantially, the apparent ecological status of macroinvertebrate communities may not reflect reduced pollution levels attained until adequate time to allow for re-colonisation (possibly decades) has elapsed.

Long-term behaviour and cross-correlation water quality analysis of the river Elbe, Germany

This study analyses weekly data samples from the river Elbe at Magdeburg between 1984 and 1996 to investigate the changes in metabolism and water quality in the river Elbe since the German reunification in 1990. Modelling water quality variables by autoregressive component models and ARIMA models reveals the improvement of water quality due to the reduction of waste water emissions since 1990. The models are used to determine the long-term and seasonal behaviour of important water quality variables. Organic and heavy metal pollution parameters showed a significant decrease since 1990, however, no significant change of chlorophyll-a as a measure for primary production could be found. A new procedure for testing the significance of a sample correlation coefficient is discussed, which is able to detect spurious sample correlation coefficients without making use of time-consuming prewhitening. The cross-correlation analysis is applied to hydrophysical, biological, and chemical water quality variables of the river Elbe since 1984. Special emphasis is laid on the detection of spurious sample correlation coefficients.

Sulphate deposition to a small upland catchment at suikerbosrand, South Africa

In 1992, a study was initiated by the Water Research Commission of South Africa, to investigate the relationship between atmospheric deposition and water quality in a small upland catchment. The selected catchment, which had a seasonal stream, was a pristine site at the Suikerbosrand Nature Reserve, which is 80 km south-east of Johannesburg. The caochment is 32.5 ha in extent and is characterised by having a quartz geology with sandy soils. Fifty-four percent of the catchment area is bare rock and the average soil depth is 15 cm. The climate is relatively arid when compared to other catchment studies in the northern hemisphere (Birkeness and Hubbard Brook) with long dry periods in the winter months and a low annual runoff (8.4 – 8.9% of mean annual precipitation). The measured inputs to the catchment included rainfall, rainwater chemistry, ambient SO2 concentrations, rock runoff and bulk or paniculate deposition. Outputs from the catchment included the measurement of runoff using a V-Notch weir and intensive sampling of a range of chemical water quality variables. During the wet summer months the dry deposition was estimated to be between 39 and 62% of the total atmospheric sulphate inputs into the catchment, whereas in the dry winter months this was estimated to be 90% of inputs. Over a complete annual cycle the net accumulation of sulphate on the catchment surface was estimated to be between 83 and 91% of inputs.

Annual variation and reliability of fecal indicators in a polluted river

AbstractFecal indicators were enumerated over a period of one year in the river Vantaanjoki discharging to the Gulf of Finland. The river was divided into three zones, one affected by nonpoint loading, another receiving treated domestic sewage, and the lower reach with no substantial further loading. The reliability of routine enumeration methods for thermotolerant coliforms and fecal streptococci was tested by isolating strains for confirmation.Fecal indicators showed wide spatial and temporal variation: the concentrations and numbers were low in summer, higher in winter under the ice cover, and highest during the periods of high discharge in spring and autumn.Of the 931 thermotolerant coliforms isolated, 74% were identified as Escherichia coli by the API 20 E identification system. A total of 3441 strains were tested for gas and indole production at 44.5°C. Of these, 73% were gas positive and 89% indole positive. Of the 3567 fecal streptococci, 67% were confirmed as catalase negative and esculin positive on bile esculin azide agar at 44.5°C. The proportion of confirmed fecal indicators varied both in different reaches of the river and seasonally. The enumeration of fecal streptococci was in some cases unreliable.Correlations between different fecal indicators and between fecal indicators and chemical water quality variables were calculated within seasons. Correlation coefficients varied with season but showed good overall compatibility.

Micro-computer applications in environmental engineering

Micro-computers can have wide applications for simulating many processes in environmental engineering. Micro-computers can have potential applications in environmental engineering for (i) selection of the best optimized water distribution network models, (ii) selection of the best optimized sewerage network models, (iii) forecasting of chemical water quality variables in surface water and (iv) modeling of contaminant transport into groundwater.