Stream water chemistry and quality along an upland–lowland rural land-use continuum, south west England

This study examined stream water quality across a range of catchments which are representative of the key environments and land uses of rural south-west England. These catchments included: (a) an acidic upland headwater catchment, rising on the moorlands of Dartmoor, with low-intensity sheep rearing; (b) a headwater catchment rising on the weathered granite lower slopes of Dartmoor, with cattle farming; (c) a lowland headwater clay catchment with sub-surface drainage and high intensity livestock farming, fodder crop cultivation, and hard-standing/slurry storage; and (d) the main River Taw, a lowland river system receiving drainage from a range of tributaries, exemplified by the above catchment types. Variations in water chemistry and quality were observed along an upland–lowland transition, from headwater streams to the main river channel. Within the livestock-dominated headwater streams, total phosphorus (TP) was dominated by particulate phosphorus (PP). These PP concentrations appeared to be mainly linked to two sets of processes: (1) in-stream sediment precipitation with sorption/co-precipitation of phosphate and/or localised in-channel mobilisation of sediment (by cattle or channel-clearing operations) under low flow conditions, and (2) sediment erosion and transportation associated with near-surface runoff during storm events. Under baseflow conditions, in-stream and/or riparian processes played a significant role in controlling general nutrient chemistry, particularly in the headwater streams which were heavily impacted by livestock.     

Spatial patterning of water quality in Biscayne Bay, Florida as a function of land use and water management

An objective classification analysis was performed on a water quality data set from 25 sites collected monthly during 1994-2003. The water quality parameters measured included: TN, TON, DIN, NH4+, NO3-, NO2-, TP, SRP, TN:TP ratio, TOC, DO, CHL A, turbidity, salinity and temperature. Based on this spatial analysis, Biscayne Bay was divided into five zones having similar water quality characteristics. A robust nutrient gradient, driven mostly by dissolved inorganic nitrogen, from alongshore to offshore in the main Bay, was a large determinant in the spatial clustering. Two of these zones (Alongshore and Inshore) were heavily influenced by freshwater input from four canals which drain the South Dade agricultural area, Black Point Landfill, and sewage treatment plant. The North Bay zone, with high turbidity, phytoplankton biomass, total phosphorus, and low DO, was affected by runoff from five canals, the Munisport Landfill, and the urban landscape. The South Bay zone, an embayment surrounded by mangrove wetlands with little urban development, was high in dissolved organic constituents but low in inorganic nutrients. The Main Bay was the area most influenced by water exchange with the Atlantic Ocean and showed the lowest nutrient concentrations. The water quality in Biscayne Bay is therefore highly dependent of the land use and influence from the watershed.     

Bioindicator role of tintinnid (Protozoa: Ciliophora) for water quality monitoring in Kalpakkam,Tamil Nadu,south east coast of India

The feasibility of a potential bioindicator based on functional groups of microzooplankton tintinnids for bioassessments of water quality status was studied during southwest monsoon (June to September) along the coastal waters of Kalpakkam, India during 2012–2015. The work highlights the following features (1) tintinnid community composed of 28 species belonging to 11 genera and 9 families, revealed significant differences among the four study sites (2) maximum numerical abundance (2224 ± 90 ind. l^? 1) and species diversity (H′ = 2.66) of tintinnid were recorded towards Bay of Bengal whereas minimum abundance (720 ± 35 ind. l^? 1) and diversity (H′ = 1.74) were encountered in the backwater sites, (3) multivariate analyses [RELATE, Biota-environment (BIOENV) and canonical analysis of principal coordinates (CAP)] reveal that chl a, nitrate and phosphate were the potential causative factors for tintinnid distribution. Based on the results, we suggest that tintinnids may be used as a potential bioindicator of water quality status in marine ecosystem.     

Impact of multispecies diatom bloom on plankton community structure in Sundarban mangrove wetland,India

A multispecies bloom caused by the centric diatoms, viz. Coscinodiscus radiatus, Chaetoceros lorenzianus and the pennate diatom Thalassiothrix frauenfeldii was investigated in the context of its impact on phytoplankton and microzooplankton (the loricate ciliate tintinnids) in the coastal regions of Sagar Island, the western part of Sundarban mangrove wetland, India. Both number (15–18 species) and cell densities (12.3 × 10³ cells l⁻¹ to 11.4 × 10⁵ cells l⁻¹) of phytoplankton species increased during peak bloom phase, exhibiting moderately high species diversity (H′ = 2.86), richness (R′ = 6.38) and evenness (E′ = 0.80). The diatom bloom, which existed for a week, had a negative impact on the tintinnid community in terms of drastic changes in species diversity index (1.09–0.004) and population density (582.5 × 10³ to 50 × 10³ ind m⁻³). The bloom is suggested to have been driven by the aquaculture activities and river effluents resulting high nutrient concentrations in this region. An attempt has been made to correlate the satellite remote sensing-derived information to the bloom conditions. MODIS-Aqua derived chlorophyll maps have been interpreted.     

南水北调东线调度对南四湖水质的影响

南水北调东线一期工程2013年通水,必将对南四湖水质产生重大影响.借鉴既有成功理论方法,建立南四湖三维水力调配和水质模型,并经实测值验证.利用该三维模型,模拟南水北调东线一个完整调水期中的南四湖常规、干旱调水工况调度运行过程,分析南四湖上级湖、下级湖的水力和水质变化规律,提出加强和改善南水北调东线调度管理的措施和建议,既可充分发挥南水北调工程效益,又可改善南四湖水质.     

Sustainability of groundwater usage in northern China: dependence on palaeowaters and effects on water quality,quantity and ecosystem health

A synthesis of groundwater ages, recharge rates and information on processes affecting groundwater quality in northern China highlights the major challenges faced for sustainable management of the region's groundwater. Direct recharge rates range from hundreds of millimetres per year in the North China Plain, to tens of millimetres per year in the Loess Plateau to less than 4 mm/year in the arid northwest. Recharge rates and mechanisms to deep semiconfined and confined aquifers are poorly constrained; however, on the basis of available data, these are likely to be mostly negligible. Severe groundwater level declines (0.5–3 m/year) have occurred throughout northern China in the last three to four decades, particularly in deep aquifers. Radiocarbon dating, stable isotope and noble gas data show that the most intensively extracted deep groundwater is palaeowater, recharged under different climate and land cover conditions to the present. Reservoir construction has reduced surface runoff in mountain‐front areas that would naturally recharge regional Quaternary aquifers in many basins. In combination with intensive irrigation practices, this has resulted in the main recharge source shifting from surface runoff and mountain‐front recharge to irrigation returns. This has reduced infiltration of fresh recharge at basin margins and rapidly increased nitrate concentrations and overall mineralisation in phreatic groundwater over wide areas (in some cases to >400 mg/l and >10 g/l, respectively). In some basins, there is evidence that poor quality shallow water has leaked into deep layers (>200 m) via preferential flow, mixing with palaeowaters stored in semiconfined aquifers. High concentrations of naturally occurring fluoride and arsenic (locally >8.5 and >4 mg/l, respectively) have recently lead to the abandonment of numerous supply wells in northern China, creating further pressure on stressed water resources. Increasing water demand from direct and indirect consumption poses major challenges for water management in northern China, which must consider the full water cycle. Copyright © 2012 John Wiley & Sons, Ltd.     

Varied impact of land use on water and sediment parameters in fish ponds of the Dombes agro-ecosystem,France

Abstract

Agricultural land use in the area of water bodies is generally considered to increase the nutrient status of the water body water and sediments, but is this also the case for already nutrient-rich fish ponds? We studied 83 fish ponds in the Dombes region, France, where 1100 ponds are located in a heterogeneous agricultural landscape. Different water and sediment parameters were analysed for ponds and in ditches after rainfall events. Land use was studied in the primary catchment of ponds and in a 100-m zone around ponds. Soil parameters of different land-use types were analysed and farmers interviewed about agricultural practices. Increasing cropping area in the catchment of the ponds is significantly correlated to higher PO₄ ^3- concentration of pond water and to a lower degree, also to NO₃ ^?, but only in certain years with higher rainfall and with a more uneven distribution in spring. Sediment parameters were not significantly influenced. High NO₃- concentration in the water of a ditch during significant rainfall events was found for a cropland dominated catchment.

Citation Wezel, A., Arthaud, F., Dufloux, C., Renoud, F., Vallod, D., Robin, J., and Sarrazin, B., 2013. Varied impact of land use on water and sediment parameters in fish ponds of the Dombes agro-ecosystem, France. Hydrological Sciences Journal, 58 (4), 854–871.     

The impact of well drawdowns on the mixing process of river water and groundwater and water quality in a riverside well field,Northeast China

Riverbank filtration (RBF) has been widely used throughout the world as an effective means to regulate surface water and groundwater resources and pretreat raw water for municipal water supply. The quality of the water from a riverside well field and the mixing ratios of surface water and groundwater is primarily impacted by the hydrodynamic processes in the RBF system. The RBF system is largely controlled by the water exploiting system in addition to the natural hydrologic condition of the river–aquifer system. As one of the most important design parameters of the riverside well field, the drawdown of groundwater level greatly determines the water head differences between the river water and groundwater as well as the field flow net, which subsequently impacts the mixing of river water and groundwater and water quality significantly. This study aimed to improve the understanding of the mixing process between the surface water and groundwater and estimate the impact of the RBF on the mixing ratio of surface water–groundwater and water quality quantitatively. A set of field pumping tests with various groundwater level drawdowns were carried out independently and successively at a riverside field with a single pumping well near the Songhua River in Northeast China in August 2017. During these tests, the water levels and hydrochemical parameters of the Songhua River, the adjacent aquifer, and the pumping well were monitored. The dynamic mixing process of the river water and groundwater and water quality under various drawdown conditions were analysed systematically using analytical methods. The results obtained from Dupuit method and the Mirror Image method in conjunction with the Hydrochemical Tracing method showed that the pumping water directly from the river water reached 60% ± 10% after a steady flow net was established. The larger the proportion of the pumping water captured from the river, the better quality of the pumping water was, because the quality of the river water (only limited to some water quality parameters monitored which were minority) was better than that of the groundwater. The results also showed that total Fe, TDS, total hardness, COD_Mn, and K⁺ were relatively sensitive to the changes of groundwater drawdown, and their concentrations decreased with an increase in the groundwater drawdown. It can be concluded that both the mixing ratio of the surface water and the groundwater and the water quality of the riverside well field can be regulated through adjusting the designed drawdown of the groundwater level, which is helpful for the design and the optimization of the riverside well water intake engineering.     

南水北调中线水源区水质生态监测(2005年)

在生态调查基础上从微生物学、理化及叶绿素a指标等对南水北调中线水源区进行了生态监测．结果表明,水源区为寡污型水体,水体基本处于贫-中营养状态,水源区指标除TN为Ⅲ类水质外,其它监测指标均符合Ⅰ类水质标准．是理想的水源地．本研究为建立中线水源区长期生态研究数据信息库及库区生态环境保护政策制定提供科学依据．     

Application of food waste based diets in polyculture of low trophic level fish: Effects on fish growth,water quality and plankton density

Food waste was collected from local hotels and fish feed pellets were produced for a 6 months long field feeding trial. Three types of fish feed pellets (control diet: Jinfeng® 613 formulated feed, contains mainly fish meal, plant product and fish oil; Diet A: food waste based diet without meat and 53% cereal; Diet B: food waste based diet with 25% meat and 28% cereal) were used in polyculture fish ponds to investigate the growth of fish (grass carp, bighead and mud carp), changes in water quality and plankton density. No significant differences in the levels of nitrogen and phosphorous compounds of water body were observed between 3 fish ponds after the half-year feeding trial, while pond receiving Diet A had the highest density of plankton. The food waste combination of Diet B seems to be a better formulation in terms of the overall performance on fish growth.