Multi-parameter Water Quality Research Articles

Hydrochemical processes in lowland rivers: insights from in situ, high-resolution monitoring

Abstract. This paper introduces new insights into the hydrochemical functioning of lowland river systems using field-based spectrophotometric and electrode technologies. The streamwater concentrations of nitrogen species and phosphorus fractions were measured at hourly intervals on a continuous basis at two contrasting sites on tributaries of the River Thames – one draining a rural catchment, the River Enborne, and one draining a more urban system, The Cut. The measurements complement those from an existing network of multi-parameter water quality sondes maintained across the Thames catchment and weekly monitoring based on grab samples. The results of the sub-daily monitoring show that streamwater phosphorus concentrations display highly complex dynamics under storm conditions dependent on the antecedent catchment wetness, and that diurnal phosphorus and nitrogen cycles occur under low flow conditions. The diurnal patterns highlight the dominance of sewage inputs in controlling the streamwater phosphorus and nitrogen concentrations at low flows, even at a distance of 7 km from the nearest sewage treatment works in the rural River Enborne. The time of sample collection is important when judging water quality against ecological thresholds or standards. An exhaustion of the supply of phosphorus from diffuse and multiple septic tank sources during storm events was evident and load estimation was not improved by sub-daily monitoring beyond that achieved by daily sampling because of the eventual reduction in the phosphorus mass entering the stream during events. The results highlight the utility of sub-daily water quality measurements and the discussion considers the practicalities and challenges of in situ, sub-daily monitoring.

Quantifying spatial variability and biogeochemical controls of ecosystem metabolism in a eutrophic flow-through wetland

Wetlands are highly dynamic ecosystems that exhibit large temporal and spatial gradients in biogeochemical and metabolic processes. While previous studies have documented temporal variability of wetland metabolism, very little is known regarding how wetland metabolism varies spatially. This is particularly relevant for constructed flow-through wetlands used to treat agricultural runoff due to growing concern over the potential for these systems to act as incubators of biological oxygen demanding (BOD) substances (i.e., algal biomass) and contributors to downstream hypoxia. This study employed a spatially explicit characterization of wetland water column properties using multiparameter water quality sondes, thus allowing the calculation of wetland metabolism across a range of spatial scales (meters to 100s of meters). This study documented a high degree of spatial variability in metabolic rates within the wetland, with average gross primary productivity (GPP) ranging from 6.41 to 13.69gO2m−2d−1, community respiration (CR) ranging from 4.85 to 9.79gO2m−2d−1, and net ecosystem production (NEP) ranging from 0.35 to 2.42gO2m−2d−1. Linkages between metabolic rates and environmental controls were quantified using a spatial/temporal statistical approach. Five key environmental parameters (turbidity, dissolved reactive phosphorus, ammonium, electrical conductivity, and temperature) were found to correlate with ecosystem metabolism. Results from this study show that despite high rates of primary productivity, high respiration rates limited NEP in this wetland due to high heterotrophic activity.

Spatial distribution characteristics of phosphorus forms in sediment of Lake Hongfeng, Guizhou Province

选取贵州省红枫湖这一典型的亚深水型人工湖泊作为对象,研究了6个代表性湖区沉积物柱芯磷的赋存形态,结合水体温度和溶解氧现场监测结果,探讨了该类型湖泊沉积物内源磷释放风险.研究结果表明,红枫湖沉积物总磷含量普遍较高,表层沉积物总磷含量均值大于1500 mg/kg,明显高于下部沉积物.NaOH-SRP和rest-P是沉积物磷的主要赋存形态.NH₄Cl-P和BD-P含量表层最高,随深度增加明显降低,rest-P含量在垂向上变化不大.人为活动是造成沉积物总磷及赋存形态空间分布差异的主要原因,工业废水和网箱养鱼活动等大大增加了沉积物NaOH-SRP含量.红枫湖深水湖区底部水温多在14.5~23.5℃之间,随季节变化底部水温差异明显,溶解氧含量通常不高于1.5 mg/L,整体处于季节性缺氧或厌氧状态.以NaOH-SRP为主的沉积物磷赋存形态和深水缺氧环境大大增加了红枫湖沉积物内源磷释放的风险,在未来的研究中亟待加强对该类型湖泊沉积物内源磷释放机制、控制因素及治理措施的研究.;Lake Hongfeng is a man-made deep lake. Phosphorus of sediment samples that were collected from representative six water areas were analyzed. Water temperature and dissolved oxygen were investigated four times in the field by multi-parameter water quality observation analyzer YSI. The results showed that total phosphorus in sediment was generally high. The average value of total phosphorus in surface sediment was more than 1500 mg/kg, significantly higher than that in the bottom sediments. NaOHSRP and rest-P were the main forms of phosphorus in sediment. NH₄Cl-P, BD-P and HCl-P contents decreased with depth, and rest-P contents were stabile in vertical. Human activities (e. g. chemical waste water and artificial fish) greatly increased NaOHSRP contents in sediment. Temperature of bottom water was between 14.5-23.5℃, and the maximum temperature differences was 9.9℃ in different seasons. The bottom water was seasonal anoxic or anaerobic, which may result in changes of sediment phosphorus forms. Risk of endogenous phosphorus release increased due to anoxic condition of sediment-water interface in deep lake.

Water Quality Automatic Monitoring System Based on GPRS Data Communications

In this paper, the water quality automatic monitoring system is discussed based on General Packet Radio Service (GPRS) platform, and the system is matched with the multi-parameter water quality monitor. The composition and operation principle of the system have been introduced. GPRS communication module connects with the multi-parameter water quality monitor through the RS232. The communication module can receive instructions of the system and send the data which has been collected by the multi-parameter water quality monitor to the monitor centre. This system has stable performance, convenient to reduce operation cost, which has obtained good effect in practical application.

Acute Physicochemical Effects in a Large River-Floodplain System Associated with the Passage of Hurricane Gustav

On 1 September 2008, Hurricane Gustav passed over the Atchafalaya River Basin (ARB) in south-central Louisiana. Anticipating physicochemical shifts due to concentrated precipitation and wind stress generated by this strong category 2 storm, we deployed a continuous recording multiparameter water quality sonde in a southern ARB bayou 3 days prior to storm arrival to document conditions before, during, and after hurricane landfall. Quarter-hourly physicochemical measurements taken over a 2-week period indicated that dissolved oxygen (DO), pH, and specific conductance all reached annual lows immediately following storm passage. The most pronounced post-storm fluctuation involved DO. Daily mean DO concentration dropped to hypoxic level (DO ≤ 2 mg/L) within 3 days of landfall, followed by near anoxic conditions within 5 days that resulted in extensive system-wide fish kills. Within 6 weeks, however, DO returned to, and pH was near pre-storm levels. To evaluate the impact of Hurricane Gustav on ARB physicochemistry, we contrasted data on DO, pH, temperature, and specific conductance collected from 16 lower ARB sampling sites over a 54-day interval prior to storm landfall with data collected during a 45-day post-storm period. Results indicated that water quality was highly dissimilar (P < 0.0001) between the two periods.

Field Application of the Pelletized Fibrous Filter Device

Due to its irregular structure, the efficiency of the pelletized fibrous filter can be improved if the target substance is line-shaped. Thus, this study was conducted to examine the applications of the pelletized fibrous filter for biological sewage water with line-shaped particles. Towards this end, the pelletized fibrous filter was applied to advanced treatments in which the particles in the sewage water in the supernatant using solid-liquid separation from the final-settling reservoir was filtered with pelletized fibrous filters. To determine the process efficiency of the filter device, a multiparameter water quality analyzer and a data transmission system were established, which showed the efficient process even at a large distance, as well as the good operational status of the filter device. The pilot plant operation results showed that the concentration of TSS in the influent at 20-75 mg/L was reduced to 0.4-10 mg/L in the processed water. The average processing efficiency was 94.9% between 71.4 and 97.9%, and particularly, that of the suspended solids was very high. The results also showed that 27.2% CODMn, 22.5% T-N, and 30.0% T-P were removed.

Analysis of Trophic State Index of Nainital Lake from Landsat −7 ETM Data

Trophic State Index (TSI) of Nainital lake has been determined using secchi disk transparency as well as using Landsat 7 ETM bands. The insitu water quality parameters like pH and dissolved oxygen (DO) have been measured using multiparameter water quality instrument TROLL 9500. Various interpolation techniques have been tested and the best one has been applied to prepare the water quality images of Nainital lake. The analysis of Landsat images have shown that the lake water is in eutrophic condition from the year 2000 to 2010. However, the trophic state index values are found to be relatively less during the year 2006 to 2008. This may be due to the lake restoration programmes undertaken by the Lake Development Authorities.

CBNERRVA Research and Monitoring Program

The overall goal of the Chesapeake Bay National Estuarine Research Reserve in Virginia (CBNERRVA) research and monitoring program is to promote, coordinate and conduct research and monitoring to enhance the scientific understanding and management of the York River and southern Chesapeake Bay coastal ecosystems. The regions of greatest scientific emphasis are located within four Reserve sites located along the York-Pamunkey River estuarine system. Primary research and environmental monitoring areas include: estuarine and shallow water environments including benthic communities, submerged aquatic vegetation and emergent wetlands habitats, open water regions and adjacent watersheds and air sheds. Both national priority (NOAA) and Chesapeake Bay specific (Chesapeake Bay Program) research focus areas are pursued within the Research Reserve with goals to: enhance scientific understanding of coastal ecosystems, surrounding environments and the natural and human processes influencing such systems; and, promote the effective management and conservation of natural and cultural coastal resources through informed decision-making. A System-wide Monitoring Program (SWMP) initiated by the Estuarine Reserves Division (ERD) of NOAA provides standardized data on national estuarine environmental trends through similar measurements of abiotic and biotic variables as well as watershed and land use classifications and measurements at each of the 27 Reserves. Data are compiled electronically at a central data management location and are available via web interface (www.vecos.org). Ongoing York River monitoring programs at the CBNERRVA reserve sites include; meteorological and streamflow monitoring, water quality monitoring and biological monitoring are available through the Reserve or via web interface. Multi-parameter water quality, in situ monitors at both fixed and buoyed stations, point sampling and continuous underway flow-through monitoring form the basis of the water quality monitoring program. Research opportunities at Reserve sites are available to any qualified scientist, academician or student affiliated with a university, college or school, non-profit organizations, and non-academic research institutions. In addition, the Reserve sponsors competitive graduate research fellowships through the NERRS Graduate Research Fellowship (GRF) Program for student research in the York River system.

Dynamic variation of supernatant quality in a dairy shed waste stabilisation pond system

An intensive monitoring program of a standard two-stage dairy shed waste stabilisation pond system was undertaken to determine the incidence and extent of spatial and temporal variation of basic physio-chemical parameters, and to shed light on the longer term dynamic nature of in-pond conditions. The anaerobic-facultative pond system, located in a remote rural area, treats wastewater from the hosing down and hydraulic flushing of the milking parlour and holding yard at the farm dairy shed. A number of multi-parameter water quality field monitoring probes were permanently deployed at various locations within the two ponds to enable continuous measurement of temperature, pH, conductivity and dissolved oxygen. In addition, profiling of the supernatant of both ponds was undertaken at different times of the year to examine vertical variation of the same parameters. Continuous monitoring revealed spatial homogeneity in EC and pH levels in the upper metre of both ponds. Physio-chemical parameters also appear to change uniformly across the ponds in response to external stimuli such as rainfall. Neither pond, however, exhibits homogeneity down the profile of the supernatant. Seasonal stratification is prevalent in the facultative pond suggesting poor vertical mixing, while the anaerobic pond is notably affected by sludge accumulation. A long-term pattern of rising conductivity in both ponds indicated accumulation of dissolved salt species in the system due to recirculation of reclaimed effluent for hydraulic flushing of the dairy shed. In the facultative pond, diurnal fluctuations in dissolved oxygen, oxidation-reduction potential and turbidity during warmer months of the year closely followed temperature swings. The extensive data collected in this study provides a detailed picture of the physio-chemical dynamics of two-stage stabilisation pond systems treating dairy shed wastewater.

Effects of Impervious Cover at Multiple Spatial Scales on Coastal Watershed Streams1

Abstract: The spatial scale and location of land whose development has the strongest influence on aquatic ecosystems must be known to support land use decisions that protect water resources in urbanizing watersheds. We explored impacts of urbanization on streams in the West River watershed, New Haven, Connecticut, to identify the spatial scale of watershed imperviousness that was most strongly related to water chemistry, macroinvertebrates, and physical habitat. A multiparameter water quality index was used to characterize regional urban nonpoint source pollution levels. We identified a critical level of 5% impervious cover, above which stream health declined. Conditions declined with increasing imperviousness and leveled off in a constant state of impairment at 10%. Instream variables were most correlated (0.77 ≤ |r| ≤ 0.92, p &lt; 0.0125) to total impervious area (TIA) in the 100‐m buffer of local contributing areas (∼5‐km2 drainage area immediately upstream of each study site). Water and habitat quality had a relatively consistent strong relationship with TIA across each of the spatial scales of investigation, whereas macroinvertebrate metrics produced noticeably weaker relationships at the larger scales. Our findings illustrate the need for multiscale watershed management of aquatic ecosystems in small streams flowing through the spatial hierarchies that comprise watersheds with forest‐urban land use gradients.

Specific Conductance and Ionic Characteristics of Farm Canals in the Everglades Agricultural Area

Specific conductance in farm canals of the Everglades Agricultural Area (EAA) in south Florida is an important water quality parameter that was categorized as a parameter of concern according to an observed frequency of >5% excursions over the Class III water quality criterion and needed to be addressed as a part of the Everglades Regulatory Program. This study was conducted to evaluate specific conductance in farm canals of the EAA. Specific conductance was monitored at 10 representative farms (a total of 12 pump stations) in the EAA using multi-parameter water quality data loggers, for periods ranging from 24 to 83 mo. Cation and anion concentrations were also determined. Nonparametric Mann-Kendall trend analyses and Sen's slope analysis of specific conductance were conducted to determine specific conductance trends. Mean specific conductance ranged from 0.74 to 1.68 dS m(-1) and only 2 of the 10 farms were above the State Class III water quality criterion of 1.275 dS m(-1). Statistically significant downward trends were observed at 3 of the 10 farms. Determination of ion compositions in grab samples at 8 of the 10 farms indicated that the major ions contributing to the increase in specific conductance in the EAA were Cl-, HCO3-, and Na+. Mean Na/Cl ratios in most of the EAA canals ranged from 0.57 to 0.78, whereas those of SO4/Cl ranged from 0.46 to 0.98. Investigation of historical data and literature indicates that elevated specific conductance in parts of the EAA is a natural phenomenon due to entrapment of connate seawater in the Everglades formation. Sulfur contributes minor increases in specific conductance in the EAA with probable sources from organic soil mineralization, ground water, Lake Okeechobee, and S fertilizers.

A universal index formula suitable to multiparameter water quality evaluation

Based on hypothesis of “base value” of water quality parameter, a universal index suitable to multi-parameter water quality evaluation was presented, as the monitoring values of parameters in the water quality index formula in logarithm function form were replaced by their relative values, and optimizing the parameters of different indices in the formula was carried out by Genetic Algorithms. Each index of water quality can be weighted into comprehensive index by compromise active function. The correctitude of formula was verified by using this method to asses the water quality states of many spots. The formula has shown its simplicity of calculation, practicability, generality, comparability and objectivity. © 2004 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 20: 368–373, 2004