Multipond Systems Research Articles

INVESTIGATING THE MICROBIOTA OF SOLAR SALTERN OF MULUND, MUMBAI, INDIA

Solar salterns, located in tropical and subtropical areas worldwide, are artificial shallow ponds for the production ofhalite (NaCl) from seawater. They are often built as multipond systems. Multi-pond solar salterns have been widespreadenvironments for studies on halophilic microorganisms. In the present study Archaeal and bacterial diversity of thesalterns located at Mulund (19°10’12’’N, 72°57’18’’E), Mumbai was investigated. Three Halophiles were isolated fromthe brine samples collected. All isolated archaea were shown intensely orange pigmentation. These salt tolerantorganisms were characterized using morphological, biochemical and 16S rRNA analysis. Phylogenetic analysis of thesesequences revealed a range of identities to several group of bacteria. The clones fell into major lineages theActinobacteria and firmicutes. Presence of industrially important carotenoids producing halophiles were also recorded.

Research and engineering application of bypass combined artificial wetlands system to improve river water quality

In this study, a water body enhancement project is conducted in Baozi River in Wuhan City, using ecological aeration, surface flow artificial wetlands, ecological gravel beds, ecological wetland multi-pond systems, underwater forest systems, and other components of the bypass treatment system as the main treatment measures. Additionally, aquatic plants are planted, ecological floating islands are installed, and a bottom sediment purifier is used as auxiliary treatment measures to improve the river water quality comprehensively. Results show that the combined process operates stably and can efficiently remove pollutants in the water body. The final monitored results show that the amount of ammonia nitrogen (NH3−N) is less than 1.0 mg/L, total phosphorus (TP) is less than 0.2 mg/L, chemical oxygen demand (COD) is less than 20 mg/L, dissolved oxygen (DO) exceeds 5 mg/L, and transparency exceeds 60 cm. Furthermore, the water quality of the river is improved from Class V water to Class III water of the China Surface Water Environmental Quality Standard (GB3838-2002), which shows the effectiveness of the water quality improvement method. Using this method to rebuild the water ecosystem improves the water quality, local urban image, environmental quality, and living environment. The combined technology can serve as reference for urban river water quality improvement.

Assessment of extrinsic and intrinsic influences on water quality variation in subtropical agricultural multipond systems.

Understanding wetland water quality dynamics and associated influencing factors is important to assess the numerous ecosystem services they provide. We present a combined self-organizing map (SOM) and linear mixed-effects model (LMEM) to relate water quality variation of multipond systems (MPSs, a common type of non-floodplain wetlands in agricultural regions of southern China) to their extrinsic and intrinsic influences for the first time. Across the 6 test MPSs with environmental gradients, ammonium nitrogen (NH4+-N), total nitrogen (TN), and total phosphate (TP) almost always exceeded the surface water quality standard (2.0, 2.0, and 0.4mg/L, respectively) in the up- and midstream ponds, while chlorophyll-a (Chl-a) exhibited hypertrophic state (≥28μg/L) in the midstream ponds during the wet season. Synergistic influences explained 69±12% and 73±10% of the water quality variations in the wet and dry season, respectively. The adverse, extrinsic influences were generally 1.4, 6.9, 3.2, and 4.3 times of the beneficial, intrinsic influences for NH4+-N, nitrate nitrogen (NO3--N), TP, and potassium permanganate index (CODMn), respectively, although the influencing direction and degree of forest and water area proportion were spatiotemporally unstable. While CODMn was primarily linked with rural residential areas in the midstream, higher TN and TP concentrations in the up- and midstream were associated with agricultural land, and NH4+-N reflected a small but non-negligible source of free-range poultry feeding. Pond surface sediments exhibited consistent, adverse effects with amplifications during rainfall, while macrophyte biomass can reflect the biological uptake of CODMn and Chl-a, especially in the mid- and downstream during the wet season. Our study advances nonpoint source pollution (NPSP) research for small water bodies, explores nutrient "source-sink" dynamics, and provides a timely guide for rural planning and pond management. The modelling procedures and analytical results can inform refined assessment of similar NFWs elsewhere, where restoration efforts are required.

Exploring the multiscale hydrologic regulation of multipond systems in a humid agricultural catchment

Assessing the hydrologic processes over scales ranging from single wetland to regional is critical to understand the hydrologically-driven ecosystem services especially nutrient buffering of wetlands. Here, we present a novel approach to quantify the multiscale hydrologic regulation of multipond systems (MPSs), a common type of small, scattered wetland in humid agricultural regions, because previous studies have stopped in commending the catchment scale flood and drought resilience of these waters, and contemporary models do not adequately represent the corresponding intra-catchment fill-spill relationships. A new version of Soil and Water Assessment Tool (SWAT) was developed to incorporate improved representation of: (1) perennial or intermittent spillage connections of pond-to-pond and pond-to-stream, and (2) bidirectional exchange between pond surface water and shallow groundwater. We present SWAT-MPS, which adopts rule-based artificial intelligence to model the possibilities of different spillage directions and GA-based parameter optimization over the two simulation years (June 2017 to May 2019), with successfully replicated streamflow and pond water-level variations in a 4.8 km2 test catchment, southern China. Water balance analysis and scenario simulations were then executed to assess the hydrologic regulation at single pond, single MPS, and entire catchment scales. Results revealed (1) the presence of 9 series- or series-parallel connected MPSs, in which pond overflow accounted for as much as 59% of the catchment water yield; (2) seasonally- and MPS-independent baseflow support and quickflow attenuation, with ranked level of pond water storage for baseflow support across different landuse types: forest > farm > village, and inversed correlation of pond spillage to baseflow and quickflow variations in the farmland; and (3) MPS-aggregated catchment flood peak reduction (>20%) and baseflow increment (26%) in the following dry days. Meteorological data analysis and simulated average daily values indicated these hydrologic patterns are credible even if extending to a 5-year period. As a first modelling attempt to explore the intra-catchment details of MPSs, our study underscores the water storage and connectivity in their hydrologic regulation, and suggests inventories, long-term field monitoring, and several research directions of the new model for integrated pond management in watersheds and river basins. These findings can inform refined assessment of similar small, scattered wetlands elsewhere, where restoration efforts are required.

Spatiotemporal patterns and source attribution of nitrogen pollution in a typical headwater agricultural watershed in Southeastern China

Excessive nitrogen (N) discharge from agriculture causes widespread problems in aquatic ecosystems. Knowledge of spatiotemporal patterns and source attribution of N pollution is critical for nutrient management programs but is poorly studied in headwaters with various small water bodies and mini-point pollution sources. Taking a typical small watershed in the low mountains of Southeastern China as an example, N pollution and source attribution were studied for a multipond system around a village using the Hydrological Simulation Program-Fortran (HSPF) model. The results exhibited distinctive spatio-seasonal variations with an overall seriousness rank for the three indicators: total nitrogen (TN) > nitrate/nitrite nitrogen (NOx--N) > ammonia nitrogen (NH3-N), according to the Chinese Surface Water Quality Standard. TN pollution was severe for the entire watershed, while NOx--N pollution was significant for ponds and ditches far from the village, and the NH3-N concentrations were acceptable except for the ponds near the village in summer. Although food and cash crop production accounted for the largest source of N loads, we discovered that mini-point pollution sources, including animal feeding operations, rural residential sewage, and waste, together contributed as high as 47% of the TN and NH3-N loads in ponds and ditches. So, apart from eco-fertilizer programs and concentrated animal feeding operations, the importance of environmental awareness building for resource management is highlighted for small farmers in headwater agricultural watersheds. As a first attempt to incorporate multipond systems into the process-based modeling of nonpoint source (NPS) pollution, this work can inform other hydro-environmental studies on scattered and small water bodies. The results are also useful to water quality improvement for entire river basins.

Migration and degradation of swine farm tetracyclines at the river catchment scale: Can the multi-pond system mitigate pollution risk to receiving rivers?

The study investigated the degradation behaviors of swine farm tetracyclines (TCs) at a catchment scale and explored whether multi-pond systems could be beneficial to the interception of TCs so as to reduce the pollution risk to receiving rivers. The occurrence and migration of 12 kinds of tetracycline antibiotics, including their degradation products, were studied in four swine farms of the Meijiang River basin in China. The migration paths of the TCs were examined through sampling and analyzing the soil and/or sediment at different points along the swine wastewater outlet, which included sewer, sewage pond, mixed-canal (stream and sewage), farmland (paddy and upland soil) and finally the river. TC concentrations of all collected samples were obtained by solid phase extraction followed by measurement with high-performance liquid chromatography tandem mass spectrometry. The results showed that sediment TC concentrations varied greatly in different swine farms, from mg·kg−1 to μg·kg−1 levels. TCs had different decay patterns along different migration paths, such that TCs decayed exponentially in paddy soil, while linearly in sewer and mixed canal. The concentrations of TCs and their degradation products decreased in the order: sewer sediment > sewage pond sediment > mixed-canal sediment > paddy soil > upland soil, indicating that TCs tend to be more easily intercepted and accumulated in water-sediment systems such as ponds. Therefore, the multi-pond system could be an effective way to prevent TCs from migrating into rivers. These results provided essential information for contamination control of antibiotics in aquatic environments.

Metagenomic Sequence of Prokaryotic Microbiota from an Intermediate-Salinity Pond of a Saltern in Isla Cristina, Spain

Marine salterns are artificial multipond systems designed for the commercial production of salt by evaporation of seawater. We report here the metagenomic sequence of the prokaryotic microbiota of a pond with intermediate salinity (21% total salts) of a saltern located in Isla Cristina, Huelva, southwest Spain.

Historical records of heavy metal accumulation in sediments and the relationship with agricultural intensification in the Yangtze–Huaihe region, China

The extensive use of fertilizers on farmlands during the past several decades in China has led to a rapid deterioration of environmental water quality in recent years. An agricultural watershed with high-yield grain production and characterized by multipond systems in the Yangtze–Huaihe region of China was selected to establish the historic records of heavy metal pollution by 137Cs-dated sediment cores. The experimental results indicated that the contents of most of the heavy metals investigated, such as Cd, Cr, Cu, Ni, Pb, and Zn, continuously increased in the multipond sediments throughout the past three decades. An inflection point appeared in the 1980s, prior to which all heavy metal contents showed little or no increase with time. Thereafter, the heavy metal contents increased dramatically due to the extensive application of phosphate fertilizers. The mean Cd content in 1980 was 0.13 μg/g which increased rapidly to 0.33 μg/g in 2004, but prior to 1980, the level was only 0.08 μg/g. Similar trends were also found for other heavy metals. The enrichment factor (EF) values indicated that Cd was not only the most anthropogenic metal in the multipond sediments but also aggravated anthropogenic impacts on the watershed environment during the past two decades. The high proportion of chemical reactive forms of Cd (10%–30%) implied a moderately high ecological risk. Our results clearly reveal that the extensive use of fertilizers has resulted in significant heavy metal pollution in this watershed, which threatens the water quality of the watershed and downstream water bodies.

Historical Distribution and Partitioning of Phosphorus in Sediments in an Agricultural Watershed in the Yangtze-Huaihe Region, China

Agricultural intensification developed rapidly in East China since the 1980s, which caused most of the lakes in these areas to become eutrophic at almost the same time. Less is known about the relationship between agricultural intensification and watershed water quality, as well as historical nutrients dynamics and lake eutrophication processes. The study area, a typical agricultural watershed with high-yield grain production characterized by multipond systems in China's Yangtze-Huaihe region, was selected to evaluate the effects of agricultural intensification on P sediment retention using 137Cs dated sediment cores. Experimental results showed that P kept increasing in the multipond sediments during the past decades, which could be attributed almost entirely to agricultural intensification. An inflection point appeared in the 1980s, before which TP showed no or only a slight increase (200 mg x kg(-1)). Thereafter, it increased dramatically (about 400 mg x kg(-1) by the year 2004) due to the extensive application of phosphate fertilizers. The chemical reactive fraction, KCl-extracted phosphorus (KCI-P), accounted for only 0.3% or less of TP. However, NaOH-extracted inorganic P (NaOH-Pi), accounting for 13-46%, was the main factor causing TP to increase due to long-term P fertilization, whereas CaCO3-bound phosphorus (Ca-P), together with residual phosphorus (Res-P) stayed at a relatively stable level. The increasing TP contents indicated that there was a potential to overwhelm the sorption capacity of multipond systems causing continuous water quality deterioration in the watershed and downstream waters. It is implied that P export resulting from agricultural intensification and water deterioration should be taken into account during the formation of watershed management strategies for the water environment.

Non-point pollution from China's rural areas and its countermeasures

Most lakes in the eastern part of China are eutrophic and non-point pollution accounts for more than half of the nutrient load to the lakes and reservoirs. Some efforts have been made to reduce the non-point source pollution in the catchments of sensitive water bodies. Technologies for the control of non-point pollution in Chinese rural areas are multipond systems, biogas fermentation, hilly area ecological agriculture, constructed wetlands, ecotone engineering and others. They are effective in the removal of nutrients from the runoff water or reduction of waste, and they are used with multi-purposes. To control non-point pollution, the cooperation with farmers and other residents in the countryside is the key to success, and the program has to consider their benefits. There are still many difficulties with its control, and more efforts are needed to develop suitable technologies and environmental education.

Multipond system: a sustainable way to control diffuse phosphorus pollution.

Diffuse pollution from agricultural land is one of the main causes for lake eutrophication. Multipond systems, an ancient invention in China, are composed of many tiny ponds and ditches, scattered in agricultural fields. After a long period of research in an experimental watershed in Liuchahe, it was found that multipond systems constitute diffuse pollution control. They have a large capacity for water storage and serve to control the export of water, suspended matter, and phosphorus. Multipond systems significantly reduce runoff velocity. Sediments and phosphorus retained in the Liuchahe watershed were 14.38 x 10(6) and 7016 kg yr-1, respectively (area 691.6 ha). Irrigation provides an effective way to recycle and remove phosphorus. The use of multipond systems is a sustainable way to recycle valuable nutrients and reduce their discharge and thus pollution of downstream lakes.

Nutrient Retention by Multipond Systems: Mechanisms for the Control of Nonpoint Source Pollution

AbstractThe processes of the multipond system in an experimental agricultural watershed located in southeastern China were studied during a 2‐yr period (1994–1995), with the purpose of the research being the reduction of nonpoint nutrient pollution at its sources. The mechanisms studied included water storage capacity, sedimentation, denitrification, and removal of nutrients by the harvest of macrophytes from ponds and ditches. The results showed that the retention of both water and nutrients depended on the water storage capacity of the ponds, the total pond volume, rainfall, surface runoff, and irrigation amounts. For the years of 1994 and 1995, the water retention rate was 85.5%, while the nutrient retention rate reached 98.1 and 97.8% for total N (TN) and total P (TP), respectively. Sediment deposit was another important mechanism. The average sedimentation rate was 30.0 mm yr−1 (from 1985–1995). For the whole multipond system (35 ha), the average retention amounts reached 9800 kg of N and 2800 kg of P by sediment accumulation per year. The results demonstrated that denitrification in ponds and ditches was an important mechanism for removing N from the watershed. The highest possible rate was more than 0.17 mg N g−1 soil during the summer season. The results suggested that the multipond system, which kept water in balance, benefited the water, nutrient, and sediment recycling in the terrestrial ecosystem, as well as helped to reduce agricultural nonpoint pollution at its sources. Therefore, the multipond system, with its low cost in construction and maintenance, is recommended as a good practice both for the control of nonpoint pollution at its sources and for sustainable agricultural development.

Occurrence and removal of Ascaris sp. ova by waste stabilisation ponds in Kenya

A study was conducted to determine the occurrence of Ascaris sp. ova in municipal wastewater and their removal by a variety of waste stabilisation pond systems in the republic of Kenya. A total of 52 wastewater samples were examined for the presence of ova, comprising 10 raw wastewater and 42 pond effluent samples over a two month period during 1990. Ascaris sp. ova were detected in 6 out of 10 designated pond systems examined. In raw wastewater, ova concentrations ranged from 17.5 to 133.3 ova/l and in pond effluents from 0.7 to 88.9 ova/l. Although the majority of ova were removed in primary ponds that received raw wastewater, ova were detected in pond effluents with estimated hydraulic retention times far in excess of estimated settling rates for Ascaris. The occurrence of ova in pond effluent samples suggested that in these multi-pond systems, estimated cumulative retention periods of 12.4 (Eldoret), 26.2 (Dandora) and 17.8 (Nakuru) days, respectively, were required to achieve an effluent free of Ascaris sp. ova. Laboratory experiments were performed to assess physico-chemical and microbiological parameters to provide an indication of pond performance.

Occurrence and removal of Ascaris sp. ova by waste stabilisation ponds in Kenya

A study was conducted to determine the occurrence of Ascaris sp. ova in municipal wastewater and their removal by a variety of waste stabilisation pond systems in the republic of Kenya. A total of 52 wastewater samples were examined for the presence of ova, comprising 10 raw wastewater and 42 pond effluent samples over a two month period during 1990. Ascaris sp. ova were detected in 6 out of 10 designated pond systems examined. In raw wastewater, ova concentrations ranged from 17.5 to 133.3 ova/l and in pond effluents from 0.7 to 88.9 ova/l. Although the majority of ova were removed in primary ponds that received raw wastewater, ova were detected in pond effluents with estimated hydraulic retention times far in excess of estimated settling rates for Ascaris. The occurrence of ova in pond effluent samples suggested that in these multi-pond systems, estimated cumulative retention periods of 12.4 (Eldoret), 26.2 (Dandora) and 17.8 (Nakuru) days, respectively, were required to achieve an effluent free of Ascaris sp. ova. Laboratory experiments were performed to assess physico-chemical and microbiological parameters to provide an indication of pond performance.