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Impact of river water and sediment properties on the chemical composition of water hyacinth and hippo grass
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Water hyacinth (Eichhornia crassipes) is a hydrophyte weed that causes havoc in the aquatic ecosystem as an invasive plant that can obstruct waterways and bring about nutrient imbalance. This study aims to address how this invasive hydrophyte can be physically harvested and biochemically transformed into a bioproduct that can enhance the restoration of damaged soil. Biocomposting, a low-cost biotechnological technique, was designed to degrade the lignocellulosic Eichhornia crassipes biomass and transform it into a valuable bioproduct. The process used response surface methodology (RSM) to investigate the aggregate effect of moisture content, turning frequency, and microbial isolate (Chitinophaga terrae) inoculum size on the breakdown of lignin over 21 days. The moisture content (A), (45, 55, 65) % v/w, inoculum size (B), (5, 7.5, 10)% v/v, and turning frequency (C), (1, 3, 5) days were considered independent variables, while percentage lignin degradation was considered a response variable. The optimal conditions for lignin breakdown were 65.7 percent (v/w) moisture, 7.5 percent (v/v) inoculum concentration, and 5-day interval turning. The R² score of 0.9733 demonstrates the model's integrity and reliability. Thus, the RSM approach resulted in a fine grain dark brown Nutri-compost that proved effective in enhancing soil fertility. This procedure is recommended for a scale-up process where large quantities of the hydrophyte could be treated for conversion into Nutri compost.
Water hyacinth covers a significant portion of Lake Tana affecting the livelihoods of thousands of rural households. The general objective of the study was to assess the impact of water hyacinth on the livelihoods of rural households living around Lake Tana. Quasi-experimental research design was applied to achieve the specified objectives of the study. Data was collected from 413 survey households, thirteen key informants, six focus group discussions and field observation. Descriptive statistics and propensity score matching (PSM) using STATA 15.0 were used for data analysis. Results of the study revealed that crop, livestock, and fishery production are the most important livelihood strategies of the study area accounting for 99.3, 95.2 and 9% of the sample households, respectively. The average annual crop production of the households was 2629.1 kg of rice equivalent. However, the weed affected the crop production of 34.1% of the sample households through covering the agricultural land and making the land preparation difficult. In addition, the weed affected 36.6% of the households’ livestock production. The impact was revealed in covering the grazing land, causing disease and/or death of the livestock and elevating the livestock production cost. Furthermore, water hyacinth was found as a reason for the reduction of fish population, blockage of fishing entry sites and disruption of the transport system. A statistically significant reduction of fish production, 45.7% in wet season and 49.9% in dry season, was generated because of water hyacinth. The PSM result showed that the water hyacinth significantly decreased the crop production (278.7- 475.4kg of rice equivalent) and livestock production (0.083-0.114 TLU) of the affected households. The study recommended management of water hyacinth to control the impacts on rural livelihoods and further studies towards medication of water hyacinth cased livestock diseases and the possible ways of the weeds consumption as a feed.
Nutrient enrichment from increased anthropogenic activities causes algal blooms and the proliferation of water hyacinth and other aquatic weeds. It is a recent phenomenon in developing nations where the link between water quality and water hyacinth infestation is not well studied. The objective of this study is to investigate the relationship between phosphorus, nitrogen, and chlorophyll-a on the distribution of water hyacinths in Lake Tana, located in the tropical highlands of Ethiopia. In this 3,000 km 2 lake, water hyacinths have expanded from almost none to 25 km 2 during the last 10 years. Water samples were taken near the four large rivers and at 27 nearshore stations. Samples were analyzed for total phosphorus, total nitrogen and chlorophyll-a. Our measurements were augmented with concentrations reported in the literature historically. Our results show that phosphorus concentration increased exponentially since the first measurements in 2003 from 0.01 mg P/l to near 1.8 mg P/l in 2020. Nitrogen concentrations increased from near zero at the end of the dry phase but remained nearly constant at around 2 mg total N/l after 2016. As a result, the ratio of nitrogen and phosphorus decreased in time, and the lake went from phosphorus to nitrogen limiting. Chlorophyll-a concentrations ranged from 0.3 to 104 µg/l. Water hyacinths appeared in the lake around 2010 after the nitrogen assimilation capacity of the lake was exceeded. They are found mainly in the northeastern part of Lake Tana, while nutrient concentrations are suitable for growing water hyacinths throughout the lake after 2010. Its location is mainly a consequence of lake circulation and wind direction. Minimum Chl-a concentrations were measured at locations with water hyacinths. Preventing future expansion of water hyacinth in Lake Tana is complicated but will require at minimum management practices that reduce the nitrogen and phosphorus loading from fertilizers applied in agriculture and prevent contributions from point sources.
Water hyacinth, the devastating weed grows in water bodies either naturally or as a result of human interference, is considered as threat to environment due to its negative effects on aquatic ecosystems. To alleviate its negative impact utilization of those become as better mean in recent decades. As such, water hyacinth is known to has potential to be utilized as nutrient source via composting, all most all types of composting techniques are applicable in preparation of compost from water hyacinth. Being an organic source, water hyacinth helps build up soil organic matter, in turn play vital role in the enrichment of the soil physical, chemical and biological properties. Aggregation of soil particles, porosity, density, water holding capacity, nutrient availability, cation exchange capacity, pH, soil microorganism are the soil properties reported to improve with water hyacinth compost application. Moreover, water hyacinth compost seems to be far better than the animal manures in improvement of soil properties. As a result, water hyacinth compost shows magnificent effect of plant agronomic growth parameters such as germination percentage, number of leaves, leaf area index, plant height, length of shoot and root, root: shoot ratio, biomass content as well as yield parameters. However, utilization of water hyacinth has few challenges like difficulties in harvesting, chance for heavy metal accumulation, hardness during decomposition, less awareness. Properly managed water hyacinth compost would serve as an alternative for inorganic nutrient sources in future thus indirectly the threat caused by this aquatic weed on environmental would become minimum.
This study aimed to develop new prediction models that include sediment properties (pH, organic matter, and silt and clay concentrations) for estimating the potential uptake of heavy metals
(HMs) by the invasive grass Vossia cuspidata. Plant and sediment samples were collected from the microsites that represent the natural distribution of the species in two Nile islands in Cairo, Egypt.
The results show that the root was the main accumulating organ for the analyzed HMs (Fe, Mn, Zn, Cu, Ni, and Pb). The mean concentrations of Fe and Mn and the maximum concentrations of Cu, Ni, and Pb were phytotoxic. The values of the bioconcentration factor were >1, while the translocation factor was >1 for Zn and Cu in rhizome and stem, Mn in leaf, and Ni and Pb in stem and leaf. There
were no significant differences between the measured and the predicted HM concentrations in all organs of the species. This indicates the excellent robustness of the developed regression models. Sixteen equations (out of 24) had high R2 values. Thus, V. cuspidata could be considered a biomonitor for HM pollution, and the developed equations will benefit the prediction of HM uptake by the
species in the River Nile ecosystem.
This study aimed to develop new prediction models that include sediment properties (pH, organic matter, and silt and clay concentrations) for estimating the potential uptake of heavy metals (HMs) by the invasive grass Vossia cuspidata. Plant and sediment samples were collected from the microsites that represent the natural distribution of the species in two Nile islands in Cairo, Egypt. The results show that the root was the main accumulating organ for the analyzed HMs (Fe, Mn, Zn, Cu, Ni, and Pb). The mean concentrations of Fe and Mn and the maximum concentrations of Cu, Ni, and Pb were phytotoxic. The values of the bioconcentration factor were >1, while the translocation factor was >1 for Zn and Cu in rhizome and stem, Mn in leaf, and Ni and Pb in stem and leaf. There were no significant differences between the measured and the predicted HM concentrations in all organs of the species. This indicates the excellent robustness of the developed regression models. Sixteen equations (out of 24) had high R² values. Thus, V. cuspidata could be considered a biomonitor for HM pollution, and the developed equations will benefit the prediction of HM uptake by the species in the River Nile ecosystem.
Nutrient resorption is an important strategy for nutrient conservation, particularly under conditions of nutrient limitation. However, changes in nutrient resorption efficiency with stand development and the associated correlations with ecological stoichiometry and homeostasis are poorly understood. In the study, the authors measured carbon (C), nitrogen (N), and phosphorus (P) concentrations in soil and in green and senesced needles along a chronosequence of Mongolian pine (Pinus sylvestris var. mongolica) plantations (12-, 22-, 31-, 42-, 52-, and 59-year-old) in Horqin Sandy Land of China, calculated N and P resorption efficiency (NRE and PRE, respectively), and homeostasis coefficient. The authors found that soil organic C and total N concentrations increased, but soil total P and available P concentrations decreased with stand age. Green needle N concentrations and N:P ratios as well as senesced needle C:N ratios, NRE, and PRE exhibited patterns of initial increase and subsequent decline with stand age, whereas green needle C:N ratios and senesced needle N concentrations, and N:P ratios exhibited the opposite pattern. NRE was positively correlated with N concentration and N:P ratio, but negatively correlated with C:N ratio in green needles, whereas the opposite pattern was observed in senesced needles. PRE was negatively correlated with senesced needle P concentration, soil-available N concentration, and available N:P ratio. The homeostatic coefficient of N:P was greater when including all stand ages than when including only those younger than 42 years. These findings indicate that tree growth may change from tending to be N limited to tending to be P limited along the Mongolian pine plantation chronosequence. Nutrient resorption was coupled strongly to tree growth and development, whereas it played a lesser role in maintaining stoichiometric homeostasis across the plantation chronosequence. Therefore, adaptive fertilization management strategies should be applied for the sustainable development of Mongolian pine plantations.
The purposed of this research was 1) described the nutrient quality of organic fertilizer made from water hyacinth with the addition of corncobs waste and soybean dregs, 2) described the difference in quality of the organic fertilizer made from water hyacinth with the addition of corncobs waste and soybean dregs, 3) described the best quality from organic fertilizer made from water hyacinth with the addition of corncobs waste and soybean dregs. The method of this research was experimental with completely randomized design. The experiment consisted of one treatment factor namely the type of raw material water hyacinth which included three types, namely P1: with the addition of corncobs waste; P2: with the addition of soybean dregs; P3: with the addition of corncobs waste and soybean dregs (50%:50% ratio). Each type of treatment was carried out three times so that the sample amounted 9. The measured parameters were nutrient content included C, N, C/N, P, K, and pH. The research was conducted at the Ecology Laboratory, FMIPA, Unesa. Data was analysed by descriptively quantitative and statistically used 1-way Anava. The results showed that 1) Based on the criteria of soil chemical properties, organic fertilizer content has the same quality in elements C, N, K, C/N (very high), pH neutral, and P was very low, 2) There was a difference in the effect of the type of material on the amount of nutrient content of organic fertilizer, 3) Water hyacinth that addition with corncobs waste had a higher amount nutrient in several elements namely C, N, K, C/N. Whereas organic fertilizer with addition soybean dregs had a higher amount of content in the element P.
The Zambezi River Basin in Southern Africa is undergoing rapid development and population growth. Agricultural intensification, urbanization and future development of hydropower dams will likely lead to a degradation of surface water quality, but there have been few formal assessments of where, how and why these changes impact specific water quality parameters based on in situ data spanning a large region. We sampled a large suite of biogeochemical water quality parameters at 14 locations in four field campaigns in central and southern Zambia in 2018 and 2019 to characterize seasonal changes in water quality in response to large hydropower dams and human landscape transformations. We find that the major rivers (Zambezi and Kafue) are very clean with extremely low concentrations of solutes, but suffer from thermal changes, hypoxia and loss of suspended sediment below dams. Smaller tributaries with a relatively large anthropogenic landcover footprint in their catchments show signs of pollution in the form of higher concentrations of nutrients and dissolved ions. We find significant relationships between crop and urban land cover metrics and selected water quality metrics (i.e. conductivity, phosphorus and nitrogen) across our data set. These results reflect a very high-quality waterscape exhibiting some hotspots of degradation associated with specific human activities. We anticipate that as agricultural intensification, urbanization and future hydropower development continue to accelerate in the basin, the number and extent of these hotspots of water quality degradation will grow in response. There is an opportunity for governments, managers and industry to mitigate water quality degradation via investment in sustainable infrastructure and practice, such as wastewater treatment, environmental dam operations, or riparian protection zones.
The present study aims at investigating the potential of the hippo grass for sequestering inorganic and organic nutrients in its biomass, in addition to its forage quality along Ismailia Canal, Egypt. Eight sites including 6 polluted and 2 unpolluted were selected for a seasonal plant, water and sediment investigations. The nutrients and nutritional value of the plant tissues were estimated. The highest aboveground biomass was recorded during summer, while the lowest was in winter. The plant had the highest contents of Na, K, N and Mg during winter, while P and Ca during spring and autumn, respectively. Also, Na, K and P had the highest concentrations (176.7 mg kg⁻¹, 206.9 mg kg⁻¹ and 1.1%) in the belowground, while N, Ca and Mg (0.9, 1.6 and 0.5%) in the aboveground organs. The contents of the investigated elements (except Na) were comparable in polluted and unpolluted canals with no significant differences. The aboveground parts had the highest values of ether extract (1.1%) during summer, crude fibres (60.2%) during spring, and total proteins (5.6%) during winter. The belowground tissues had the highest values of metabolized, digestible and net energy (2.4, 2.0 and 1.0 Mcal kg⁻¹) during winter. In contrast, the aboveground shoots had the highest amounts of digestible crude protein (1.7%) during winter and gross energy during spring. The nutritional value of the hippo grass from unpolluted canals were greater than polluted ones for both above- and belowground parts. Hippo grass can sequester large amounts of nutrients. Consequently, this plant can be used in restoring eutrophic water through harvesting the aboveground biomass during the growing season. Besides, the aboveground shoots of the hippo grass could be used as a forage for dairy cattle, goat, beef cattle and sheep.
The present study aimed at investigating (1) the seasonal concentrations of heavy metals in different organs of Vossia cuspidata (Roxb.) Griff. in its main natural habitats in the River Nile ecosystem in Cairo, Egypt, (2) the bioaccumulation and translocation of heavy metals in the organs of V. cuspidata and its potentials as a phytostabilizer, and (3) the seasonal changes in the dry matter (DM) biomass of the organs. Two river islands were selected for seasonal sampling of water, sediment, and plant organs in eighteen randomly distributed quadrates (0.5 × 0.5 m each) during the period from February 2018 to January 2019. The total annual mean DM biomass was ≈ 18.7 ton ha⁻¹. The aboveground organs had significant seasonal variations in DM biomass (p < 0.05). The belowground DM biomass represents 23% of the aboveground DM biomass. Belowground organs had the highest DM biomass values in winter for the roots (23.85 g DM m⁻², 4.75% from the total DM) and spring for the rhizomes (108.96 g DM m⁻², 37.3% from the total DM). Regardless of the heavy metals concentrations in water and sediment, V. cuspidata can accumulate Fe, Mn, Ni, and Pb at high levels. There was a statistically significant interaction between the effects of seasons and organs on the concentrations of Mn, Ni, and Pb at p < 0.001. The root was the main accumulating organ for the analyzed elements in the present study. Vossia cuspidata can transfer low concentrations of the analyzed metals from belowground to aboveground organs. We recommend V. cuspidata as a potential phytostabilizer to Fe, Zn, Mn, Cu, Ni, and Pb from the mainstream of River Nile.
Objective: Biomonitoring pollution of water bodies with heavy metals using evaluation of the level of concentration of heavy metals in water, aquatic plants, and sediments in 9 important rivers and lakes in the water bodies of Yekaterinburg. (Eight rivers and one lake). Methods : Sample preparation for the atomic absorption determination of the acid-soluble “mobile” form of eight metals (Mn, Fe, Co, Ni, Cu, Zn, Cd, Pb) in the composition of bottom sediments was carried out by the method of wet mineralization in accordance with the Methodological Guidelines the definition of heavy metals. Results: All concentrations of heavy metals in sediments and aquatic plants were higher than in a water sample. Conclusions : Concentrations of all water samples were within acceptable limits established by WHO, while the concentrations of all aquatic plants and sediment were above the acceptable limits of WHO.
Globally, water hyacinth is a known invasive species that predominantly threatens the pillars of sustainability. The cost of controlling these invasive plants is high and many Southern African countries are barely equipped for this liability as the process has to be performed over time. Despite this challenge, there is valuable resource recovery from water hyacinth which can be used to make financial and environmental returns. The visible differences between the control and utilisation methods lie in the definition, recognition, and matching of costs and benefits. Using a rapid appraisal of existing literature, which was analysed using meta-analysis, the current paper is an attempt to discuss the beneficial use of water hyacinth. It is argued in the paper that the economic feasibility of control methods which, on one hand, are used to calculate the economic value of water hyacinth, mainly relies on assumptions whose reliability and sustainability are questionable, thus implying limitations on using this kind of control methods. On the other hand, the costs and benefits of utilising water hyacinth can be quantifiable, making them susceptible to changes associated with time value and sensitivity analysis of possible fluctuations in cashflows. In the context of these annotations, other scholars have argued for the consideration of other utilisation alternatives, among which is included biogas which has been identified as the most viable option because of its potential in diversifying the energy mix, reducing greenhouse gas emissions, and contributing to improved water quality. Given these observations, this paper aims to contribute to policy and research discussions on the fiscal understandings of the material recovery from water hyacinth to promote the adoption of biogas technology. These views are discussed within the broader discourse of the sustainable development goals (SDGs).
One prominent effect of nutrient pollution of surface waters is the mass invasion of floating plants, which can clog waterways, disrupting human use of aquatic systems. These plants are widely vilified and motivate expensive control campaigns, but their presence may be providing a poorly recognized function in the cycling of excess nutrients. The capacity for floating plants to absorb nutrients from surface water has been understood for decades, primarily from their use in constructed wetlands for wastewater treatment. Yet, in natural settings, there has not been to date any effort to quantify whether floating plant invasions represent important pools or fluxes of nutrients relative to those of the river catchments in which they occur. We found that seasonal hydrologic cycles in the Zambezi trap and flush floating plants from river choke points, such as dams and river confluences, on an annual basis. Peak plant biomass at such choke points constitutes a proxy for estimating annual plant-bound nutrient loads. We assessed the significance of floating vegetation as nutrient sinks by comparing annual plant-bound nutrient loading to conventional river nutrient loading (dissolved and particulate) for four tributaries of the Zambezi River in Zambia. We found that the relative importance of floating vegetation was greatest in the more urbanized catchments, such as the Maramba River draining the city of Livingstone, representing approximately 30% and 9% of annual digestible phosphorus and nitrogen flux respectively. We also found plant-bound phosphorus to be important in the Kafue River (19%), draining the industrial town of Kafue and extensive sugarcane plantations. These results demonstrate the great potential of floating plants to take up excess nutrients from natural river systems. Given the importance of hydrology in the life cycle of floating vegetation, controlled dam discharges may have an important role in managing them and their water quality treatment functions.
Toxic metals are a major group of water pollutants that find their way into water bodies through municipal, industrial, and agricultural waste discharges. Phytoremediation of these metals has become popular because of the low-cost and environmental friendliness of the technique. Here, we evaluated the potential of Eichhornia crassipes (water hyacinth, WH) to remove lead (Pb), copper (Cu), and iron (Fe) from polluted waters. Five experimental prototypes (A-E) were developed for the phytoremediation. Prototypes A, B, C, and D contained 2 L of the underlay water spiked with 1, 2, 5, and 10 mL of Pb, Cu, and Fe stock solutions, respectively, whereas prototype E was the control (i.e., deionized water). About 200 g of live WH of the same rootstock was relocated into each prototype and exposed to the same environmental conditions. The concentrations of the metals were measured every three days for a 12-day remedial period. Also, the metal concentrations in the plant tissues (leaf, stem, and root) were monitored. We observed that in prototypes A and B, the WH achieved significant Cu, Pb, and Fe removal after 12 days. The removal efficiency (RE) of 45.81%, 19.29%, and 72.03% were achieved for Pb, Cu, and Fe, respectively in prototype A, whereas it was 25.63%, 10.69%, and 42.77% in prototype B. Generally, the order of removal followed the order Fe > Pb > Cu. Likewise, the metal contents found accumulated in the plant tissues followed the same order. The leaves of WH in prototypes C and D showed rapid wilting and final death by the 12th day. Consequently, phytoaccumulation was established because the metal concentrations were in the order: root > stem > leaves.
Rapid global environmental changes could exacerbate the impacts of invasive plants on indigenous plant diversity, especially for freshwater ecosystems characterized by relatively simple plant community structures with low bioresistance. However, the abiotic and biotic determinants of plant diversity in aquatic invaded habitats remain unclear. In this study, we measured four α-species diversity indices (the Patrick richness index, Shannon–Wiener diversity index, Simpson diversity index, and Pielou evenness index) in aquatic plant communities invaded by Eichhornia crassipes in southern China. We also recorded eight environmental parameters of these communities (longitude, latitude, elevation, dissolved oxygen, water conductivity, nitrate nitrogen, temperature, and precipitation), together with nine biotic traits of E. crassipes [abundance, invasion cover, height, total carbon (C) content of the leaves and stems, total nitrogen (N) content of the leaves and stems, and the C:N ratio of leaves and stems]. We then used regression analysis and redundancy analysis (RDA) to determine the dominant factors related to plant diversity. We found that the environment significantly affected E. crassipes abundance, height, coverage, stem carbon, and tissue nitrogen, while the leaf C:N stoichiometric ratio was relatively stable. Increasing longitude significantly increased plant diversity, while elevated dissolved oxygen and precipitation slightly improved plant diversity, but increased elevation caused negative effects. E. crassipes invasion significantly decreased all four diversity indices. Increases in E. crassipes coverage and leaf C:N strongly decreased plant diversity, and increased abundance slightly decreased diversity. Our study indicates that both the changing water environment and the properties of the aquatic invasive plants could have significant impacts on plant diversity. Thus, more attention should be paid to aquatic invasion assessment in lower longitudinal regions with lower native hydrophyte diversity.
Water hyacinths pose serious challenges to humanity and the environment. Considering the enormity of the menace associated with the growth and spread of the plant and the difficulty in achieving a single, generally acceptable control method, it is becoming increasingly imperative to explore the potentials of the plant. New water hyacinth-related articles are regularly being published. Recently published articles about the plant were accessed, and the information in these articles is presented in the context of the pros and cons of the plant. Some of the benefits that can be derived from the plant include biogas and biofuel production, medicinal functions, vermicomposting, compost production, and bioremediation. However, clogging of waterways, obstruction of water transportation, and fishing activities; breeding grounds for pests and diseases; and reduction of water quality, loss of biodiversity, and economic downturn in areas invaded by the plant are problems associated with it. The peculiarity in the invasiveness of each situation should determine whether or not the growth of the plant is a problem, especially if the opportunity to harness the potentials of the plant exists. There are three major methods for controlling the plants when control becomes inevitable: mechanical, chemical, and biological. To achieve the best control, integrating two or more control methods is advised.
Among the greatest challenges of Sub-Saharan Africa is the need for more crop production for supplying the increasing demand of its growing population. For this purpose, knowledge on soil resources and their agricultural potentials is important for defining proper and appropriate land use and management. We thus investigated on the status of soil fertility in Tombel area, in order to produce such knowledge through understanding and monitoring the impact of physicochemical properties of soil. Diverse analyses performed on various datasets demonstrated the direct impact of physicochemical properties of soil and derived soil fertility parameters on major constraints for plant growth and optimal crop production such as water retention capacity, roots development, soils aeration, nutrients availability, nutrients abundance and cations balance. Based on physicochemical soil properties, fertility parameters and Soil Quality Index (SQI), four soil fertility classes were identified in the area: (i) very good fertility soils (66 km²) that corresponds to Dystric Vitric Andosols (Melanic) above 500m asl; (ii) good fertility soils (506 km²), grouping Dystric Vitric Andosols (Melanic) below 500m asl and Leptic Fragic Umbrisols; (iii) fairly good fertile soils (787 km²) including Dystric Fragic Cambisols (Humic), Rhodic Acrisols (Cutanic Humic), Fragic Umbrisols (Arenic), and Mollic Ferralsols (Eutric Humic); (iv) poorly fertile soils (375 km²) including Umbric Andosols (Fragic) and Umbric Pisoplinthic Plinthosols (Haplic Dystric). The principal indicators controlling soil quality in the Tombel area as derived from ANOVA and PCA analyses, are: Ca, Mg, pH water, organic matter (OM), available P, total Nitrogen and CEC. Four of the seven indicators (Ca, pH, OM, P) were also identified as important indicators for assessing the fertility status of the different soils groups in the Tombel area.
Water hyacinth is a free floating aquatic weed native to South America. It has spread to tropical and subtropical parts of the World since 1800s. Climatic and water conditions are the main determinant factors for the growth and expansion of water hyacinth. The weed has substantial negative impacts on hydrology, socioeconomics, and aquatic ecosystem. Although hyacinth preventive strategies are best, once water bodies are infested, integrated measures are recommended to manage the weed. Lake Tana, largest fresh water body in Ethiopia, is recently infested by water hyacinth since 2011. The area sensitive to water hyacinth infestation in Lake Tana is estimated to be about 24,800ha, which covers ≤6m of the lake depth, excluding the surrounding wetlands and flood plains. The lessons for management of Lake Tana water hyacinth are employing preventive and integrated management approaches. Reducing pollutant loads and nutrient enrichment through integrated watershed management is also suggested to reduce the Lake eutrophication.
Water hyacinth invasion has been highlighted to be a source of problem to riparian communities. They are known to reduce the velocity of water bodies, thereby serving as suitable breeding grounds for mosquitoes. Their obstruction to water transportation also means students who cross invaded water bodies to school will have their education negatively affected. Based on cross-sectional research with 305 respondents who were sampled using snowballing sampling procedure, this study assesses the effects of water hyacinth invasion on the health of the communities, and the education of children along River Tano and Abby-Tano Lagoon in Ghana. We found that water hyacinth invasion in the two water bodies was associated with malaria infestation. The blockade created also meant students delayed in their quest to access their schools. However, respondents mainly used insecticide-treated nets to cope with the spread of the mosquitoes that bred in the water hyacinth while parents made provision for their wards to stay outside the affected village across the River Tano in order to attend classes in the peak season of the invasion. We recommend that further studies should target only those people whose children cross River Tano to attend school in the Adusuazo community and increase their sample size. This will help gather detailed information on the effects of the invasion on the education of children. We also recommend that further studies should be conducted to provide more concrete data on the categories of respondents whose health are more affected by the invasion and their adaptive strategies.
The Chongwe River Catchment (CRC) is located in Zambia. It receives a mean annual precipitation of 889 mm. The catchment is facing growing anthropogenic and socio-economic activities leading to severe water shortages in recent years, particularly from July to October. The objective of this study was to assess the available water resources by investigating the important hydrological components and estimating the catchment water balance using the Water Evaluation and Planning (WEAP) model. The average precipitation over a 52 year period and a 34 year period of streamflow measurement data for four stations were used in the hydrological balance model. The results revealed that the catchment received an estimated mean annual precipitation of 4603.12 Mm³. It also released an estimated mean annual runoff and evapotranspiration of 321.94 Mm³ and 4063.69 Mm³, respectively. The estimated mean annual total abstractions in the catchment was 119.87 Mm³. The average annual change in the catchment storage was 120.18 Mm³. The study also determined an external inflow of 22.55 Mm³ from the Kafue River catchment. The simulated mean monthly streamflow at the outlet of the CRC was 10.32 m³/s. The estimated minimum and maximum streamflow volume of the Chongwe River was about 1.01 Mm³ in September and 79.7 Mm³ in February, respectively. The performance of the WEAP model simulation was assessed statistically using the coefficient of determination (R² = 0.97) and the Nash–Sutcliffe model efficiency coefficient (NSE = 0.64). The R² and NSE values indicated a satisfactory model fit and result. Meeting the water demand of the growing population and associated socio-economic development activities in the CRC is possible but requires appropriate water resource management options.
Invasive aquatic macrophytes in Lake Victoria including water hyacinth (Eichhornia crassipes) exhibit periodic cyclical patterns of decline and proliferation with attendant ecological and economic impacts. This study aimed to monitor the extent of macrophytes and other invasive weeds on Lake Victoria to establish their impact on fisheries. The study employed a combination of remote sensing and geographical information system (GIS) techniques to estimate the coverage of water hyacinth and other invasive macrophytes. Data on fish landings and their respective market values were acquired from the Electronic Fish Market Information Service (EFMIS) database, which is hosted by the Kenya Marine and Fisheries Research Institute (KMFRI). Analysis of consistent temporal satellite data showed that the weeds frequently cover sheltered bays and river mouths. These areas of Winam Gulf had higher coverage (average 5000 ha) of macrophytes than the open waters (<200 ha). The proliferation of the invasive weeds showed fluctuations over the study period reaching the highest peak between September and November 2016. Other aquatic plants that have invaded the littoral areas of Lake Victoria include Egeria densa, Ceratophyllum demersum and Potamogeton spp. Increased coverage of macrophytes was found to be correlated inversely with the commercially important tilapia Oreochromis niloticus, but not with other species. The study concludes that there is a need for sustained monitoring of the invasive macrophytes alongside ecosystem modelling studies using the available time series data to clearly identify the ecological factors that drive water hyacinth dynamics and predict more precisely its impact on the fishery.
The unchecked growth of Eichhornia crassipes can cause significant harm, including covering of the water surface, depletion of oxygen, clogging of river channels, and promotion of the breeding of flies and mosquitoes. These effects can significantly impact farmland irrigation, water transportation, and human health. However, methods for controlling its growth are not ideal, and control using biological and chemical agents can result in secondary pollution. The utilization of E. crassipes as a resource, for example, as animal feed or organic substrates, can not only turn waste into valuable resources, but it can also solve the problem of its growth, thus bringing about economic and ecological benefits. In this paper, the growth and ecological characteristics of E. crassipes, its nutrient composition, and resource utilization approaches were reviewed. The challenges associated with the large-scale utilization of E. crassipes were also analyzed in order to provide references for the control and resource utilization of the species. Regarding challenges such as the difficulty of cultivation and the high cost of harvesting and dehydrating, it is necessary to investigate the proper water surface and coverage characteristics of E. crassipes cultivation to assure adequate biomass and protect the ecological landscape. It is also necessary to evaluate the effect of E. crassipes cultivation on the health of aquatic ecosystems and the safety of the water environment in order to prevent the significant potential ecological and environmental risks. In addition, developing portable, high-efficiency facilities to promote the effectiveness of harvesting, transportation and dehydration are needed, as well as further improvement in the techniques of utilization and assessment of the economic value.
Macrophyte assemblages are composed of species with different life forms and various ecological functions. Our aim was to investigate the potential environmental determinants of changes in the biomass of individual life forms and of the composition of the macrophyte assemblage in terms of life forms diversity. We sampled 23 waterbodies at low and high water levels in the Middle Paraná River floodplain. Macrophyte biomass samples were collected and classified in terms of life forms. We performed a redundancy analysis using the biomass of the various life forms to assess the importance of environmental variables to the composition of macrophyte life forms. Linear regressions were applied to investigate the environmental determinants of the biomasses of individual life forms. The degree of connectivity and the combination of depth, hydrology and nitrate were the main determinants of the composition in terms of life forms. The biomass of each individual life form was explained by different combinations of environmental variables, but the connectivity was the most important one. Our study shows that groups of species with similar life forms respond to environmental factors in particular ways, which might alter the biomass composition of life forms. Given that the ecosystem functioning depends on the functional characteristics of local communities, our findings about the relation between environmental changes and the community composition in terms of life forms (or functional composition) can be a helpful tool for predicting changes on ecosystem processes (such as nutrient cycling) against possible future scenarios.
Zambia’s Kafue River receives wastes from various sources, resulting in metal pollution. This study determined the degree of contamination of 13 metals (Al, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Cd, Hg and Pb) in Kafue River sediment and the associated ecological risks at six sites in three different seasons. The level of contamination for most metals showed significant site and seasonal differences. The contamination factor and pollution load index indicated that concentrations of most metals particularly copper (Cu), cobalt (Co), manganese (Mn) and arsenic (As) were very high at sites within the Copperbelt mining area. The geoaccumulation index showed an absence of anthropogenic enrichment with Cd and Hg at all the study sites and extreme anthropogenic enrichment with Cu at sites in the Copperbelt mining area. Potential ecological risk showed that Cu and As were likely to cause adverse biological effects to aquatic organisms in the Copperbelt mining region of the Kafue River.
Compost application to soil leads to the improvement of its properties. However, nutrient
content and an enhancing capacity of compost are highly dependent on the original source and
additive. The purpose of the experiment was to investigate selected soil quality indicators’
improvement and sweet corn growth following application of water hyacinth compost.
Greenhouse experiment was carried out using Completely Randomized Design with 2 factors.
The first factor consisted of soils from humid tropics, i.e. Andepts, Udepts, and Udults and second
factor comprised of water hyacinth compost rates, i.e. 0, 5, 10, 15, 20, and 25 Mg ha
.
Treatment combinations were replicated 3 times. Compost was incorporated in soil a week
before planting of sweet corn. After reaching maximum sweet corn growth, soil sample was
collected, air-dried, grinded and passed through 0.5 mm screen, and analyzed for selected soil
properties, except microbial biomass carbon (MBC) and particulate organic matter carbon
(POMC) which were analyzed using fresh soil sample. The experiment pointed out that
application of water hyacinth compost on Udepts exhibited the highest total soil organic carbon
(TSOC), MBC, soil pH and available P (Bray I), followed by those in Andepts and Udults.
Particulate organic matter carbon (PMOC), however, was highest in Andepts as compared to
other soils. Higher rates of compost application contributed a higher increase in TSOC, MBC,
soil pH, available P, and exchangeable K. Udults had a more pronounced increase in soil pH and
decline of exchangeable Al than other soils. Pearson correlation analysis showed that the most
distinct correlation among soil properties was observed between exchangeable Al and soil pH,
followed by TSOC and MBC with coefficient correlation of -0.91 and 0.85, respectively.
Correlation between soil properties and sweet corn growth exhibited that the most prominent
correlation was shown between available P and shoot dry weight of sweet corn with a coefficient
correlation of 0.92. This indicates that soil available P has a significant contribution to sweet
corn growth.
Limnobium laevigatum (Hydrocharitaceae) is a freshwater plant indigenous to Central and South America, which has become naturalized and invasive in parts of North America, Asia and Australia and has been detected in Southern Africa. Populations have been found in Zimbabwe and Zambia over the last eleven years and we warn of its likely spread to other parts of Africa and the likelihood of it becoming invasive in tropical Africa.
We report results from an evaluation of the levels of heavy metals, i.e., copper (Cu), cadmium (Cd), lead (Pb), nickel (Ni), manganese (Mn), chromium (Cr), and iron (Fe) in sediment and tilapia fish samples from a wide stretch of the Kafue river of Zambia. In sediment samples, the highest Pb and Fe concentrations were recorded at Hippo Dam, i.e., 36.2 ± 0.1 mg/kg dw and 733 ± 37 mg/kg dw at Kafue Town, respectively. Other notably high metal concentrations in sediment were Cr at Kafue Bridge (42.5 ± 0.1 mg/kg dw [dw]), Cu at Mpongwe (233 ± 5 mg/kg dw), and Mn at Kafue Town (133 ± 1 mg/kg dw); it was highest at Ithezi Tezhi Dam at 166 ± 1 mg/kg d. Three fish species, i.e., three-spot bream Tilapia andersonii, red-breasted bream T. rendalli, and nile tilapia Oreochromis niloticus were evaluated for levels of the seven metals. The concentrations of the metals in these fish species afforded estimation of the biota sediment-accumulation factor, which is the ratio of the concentration of the metal in liver to that in the sediment. The coefficients of condition (K) values, which give an indication of the health of the fish, were also estimated. The K values ranged from 2.5 ± 0.5 to 5.1 ± 0.6 in all of the three fish species. Partial least squares analysis showed that heavy metals are generally sequestered evenly in all of the parts of all of the three fish species except for elevated levels of Mn, Cd, and Pb in the liver samples.
Increasing concentration of nutrients in water is regarded as one of the most important external factors responsible for the invasion of the common water hyacinth. In order to test whether nutrient availability limits the growth and spread of this species, we investigated the influence of water nitrogen (N) and phosphorus (P) concentrations on growth using both greenhouse and field experiments. We found that in the greenhouse experiment, only high P concentration (>1.25 mg l-1) can significantly increase numbers of ramets and leaves, and N concentration exceeding 62.5 mg l-1 can greatly increase water hyacinth biomass in a tank. In the field experiment, the clonal growth of water hyacinth was not correlated with N and P concentrations in water bodies where the range of N and P concentrations was narrow compared with their range in the greenhouse. This suggests that controlling water hyacinth through minimizing sewage discharging is impractical, the importance of the ability of water hyacinth to grow clonally should be considered.
Eichhornia crassipes, commonly known as water hyacinth, is a free-floating perennial aquatic plant native to South America, which has been widely introduced on different continents, including Africa. E. crassipes is abundant in both the Congo (Africa) and Amazon (South America) River catchments. We performed a comparative analysis of the ostracod communities (Crustacea, Ostracoda) in the E. crassipes pleuston in the Amazon (South America) and Congo (Africa) River catchments. We also compared the ostracod communities from the invasive E. crassipes with those associated with stands of the native African macrophyte Vossia cuspidata. We recorded 25 species of ostracods associated with E. crassipes in the Amazon and 40 in the Congo River catchments, distributed over 31 ostracod species in E. crassipes and 27 in V. cuspidata. No South American invasive ostracod species were found in the Congolese pleuston. Diversity and richness of Congolese ostracod communities was higher in the invasive (Eichhornia) than in a native plant (Vossia). The highest diversity and abundance of ostracod communities were recorded in the Congo River. The result of principal coordinates analysis, used to evaluate the (dis)similarity between different catchments, showed significant differences in species composition of the communities. However, a dispersion homogeneity test (PERMDISP) showed no significant differences in the variability of the composition of species of ostracods (beta diversity) within Congo and Amazon River catchments. It appears that local ostracod faunas have adapted to exploit the opportunities presented by the floating invasive Eichhornia, which did not act as “Noah’s Ark” by introducing South American ostracods in the Congo River.
This study aimed at verifying the lead tolerance of water hyacinth and at looking at consequent anatomical and physiological modifications. Water hyacinth plants were grown on nutrient solutions with five different lead concentrations: 0.00, 0.50, 1.00, 2.00 and 4.00 mg L-1 by 20 days. Photosynthesis, transpiration, stomatal conductance and the Ci/Ca rate were measured at the end of 15 days of experiment. At the end of the experiment, the anatomical modifications in the roots and leaves, and the activity of antioxidant system enzymes, were evaluated. Photosynthetic and Ci/Ca rates were both increased under all lead treatments. Leaf anatomy did not exhibit any evidence of toxicity effects, but showed modifications of the stomata and in the thickness of the palisade and spongy parenchyma in the presence of lead. Likewise, root anatomy did not exhibit any toxicity effects, but the xylem and phloem exhibited favorable modifications as well as increased apoplastic barriers. All antioxidant system enzymes exhibited increased activity in the leaves, and some modifications in roots, in the presence of lead. It is likely, therefore, that water hyacinth tolerance to lead is related to anatomical and physiological modifications such as increased photosynthesis and enhanced anatomical capacity for CO2 assimilation and water conductance.
The bioavailability and leachability of heavy metals is important role when considering their toxicity during composting following land application. Therefore, studies were carried out on Zn, Cu, Mn, Fe, Ni, Pb, Cd and Cr during 30 days agitated-pile composting of water hyacinth (Eichhornia crassipes). This study investigated the influence of parameters such as pH, temperature and organic matter content on the distribution of heavy metal bioavailability and leachability during composting of water hyacinth. Results showed that the contents of total metal concentration increased during the composting process. The bioavailability of heavy metals was investigated in the form of water soluble and diethylene triamine pentaacetic acid (DTPA) extractable. In the water soluble, DTPA and leachable Zn, Cu, Mn, Ni and Cr reduced but there was a gradual increase in the Fe concentration during the composting process. Furthermore, in water soluble and leachable Ni, Cd and Pb were not detected and in DTPA extractable Cd and Pb were also not detected during 30 days of composting.
Eichhornia crassipes or water hyacinth is a free-floating plant, growing plentifully in the tropical water bodies. This invasive weed poses multiple hazards ranging from ecological and economical to social. It tends to endanger biodiversity, cause eutrophication, shelter pests, clog fresh waterways, affect agriculture and aquaculture, hamper shipping and recreational activities. Existing control methods have been insufficient to contain its aggressive propagation. Recently, it has been envisaged that successful utilization of this weed can solve the associated problems associated with them. It is being speculated that the huge biomass can be used in waste water treatment, heavy metal and dye remediation, as substrate for bioethanol and biogas production, electricity generation, industrial uses, human food and antioxidants, medicines, feed, agriculture and sustainable development. Towards this quest many approaches have been undertaken and partial success is achieved. If harnessed properly, this weed-based green technology can solve many of the issues our society faces now. In this context, the papers published in recent years have been reviewed, with the objective of creating public awareness and bolstering management and utilization of this cumbersome invasive weed.
Many lakes and rivers all over the globe are experiencing environmental, human health, and socioeconomic development issues due to the spread of invasive water hyacinth (WH) weed. WH is regarded as one of the world's most destructive weeds and is nearly impossible to control and eliminate due to its rapid expansion and ability to double its coverage area in 13 days or fewer. However, most people in developing countries appear to be hoping for a miraculous cure; there are none and never will be. In this regard, this chapter aims to give an insight to raise awareness, research its biology and challenges, management options, and potential prospects on integrated control-valorization and its policy implications. WH biomass has demonstrated potential as a biorefinery feedstock for bioenergy and biofertilizer production, heavy metal phytoremediation, handicraft and furniture making, animal feed, and other applications. As a result, large-scale integrated control and valorization is an economically viable strategy for preventing further infestation through incentivizing WH control: providing a sustainable environment, increasing energy mix, increasing fertilizer mix, increasing food security, reducing GHG emissions, boosting socioeconomic development, and creating new green jobs for local and riparian communities. Therefore, it is a leap forward in addressing global sustainable development goals (SDGs) through the water-energy-food-ecosystem (WEFE) nexus.
Vossia cuspidata (Roxb.) Griff. (Poaceae) is a serious invasive plant in Africa, capable to
colonize several riverine wetlands. Controlling of any invasive plant is hampered by the lack of studies involving its growth ecology. Here, we aimed to evaluate the monthly and seasonal variations in the dry biomass partitioning of V. cuspidata and its macronutrients in three aquatic habitats (slopes, water edges and open water) along the banks of the River Nile in Cairo, Egypt. In the study area V. cuspidata started its growth in February 2018 by the formation of shoots, which sprouted from buds on the underground rhizomes, showed its maximum growth in autumn and entered the senescent stage in early winter. The monthly maximum biomass dry matter (BDM) of the root system (48.9 g DWm-2) occurred in October, and in April for rhizomes (110.4 g DWm-2). The BDM production of leaves was minimum in March at the three habitats while its maximum was obtained in September or October reaching 326.6 g DWm-2 on slopes, 303.6 g DWm-2 in water edges and 246.6 g DWm-2 in open water, respectively. The maximum monthly
total BDM partitioning of V. cuspidata was 604.5 g DWm-2 on the slopes during September and reached 543.8 and 550.0 g DWm-2 in open water and water edges, respectively, during October. The highest total BDM production was obtained in autumn, while the mean of BDM of the four seasons was 1869.7 g DWm-2 ±150.9. Generally, the concentrations (% biomass DW) of the analyzed nutrient elements (K, Ca, Mg, N and P) showed mostly a gradual decrease with time during the year; starting from spring until summer or autumn, then increased again in autumn or winter. An important result of this study is that to conserve other native species, then the harvest of the aboveground organs of V. cuspidata should be carried out during late autumn in November after the translocation of reserved materials from the belowground organs to maximize V.
cuspidata biomass removal.
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A three-year river monitoring was carried out in the Bystrzyca River catchment (Poland) dominated by arable areas and wastewater treatment plants. The concentrations of potassium (K) – “a neglected nutrient” – in fresh waters were determined. Analysis of variance (ANOVA) and principal component analysis (PCA) showed spatial and seasonal variability in potassium concentrations. The highest potassium levels were observed in sites located directly below the outlet of the sewage treatment plant of Lublin. The impact of smaller sewage treatment plants on the water quality of the Bystrzyca River was low. Contents of K+ in waters situated in areas experiencing crop and animal production were significantly lower in comparison to ‘sewage’ points. There was a differentiation of correlations between concentrations of K and ammoniacal nitrogen, nitrate nitrogen and phosphate phosphorus depending on the source of pollution. The potassium levels in river waters usually decreased in early spring.
The correction of soil fertility constraints is necessary for the successful production of sugarcane. Inhibition of potassium (K) uptake by sugarcane plants in the presence of high concentrations of calcium (Ca) and magnesium (Mg) has been reported, with some sugarcane-growing countries adjusting K fertiliser recommendations accordingly. Although the depressive effect of K on Ca and Mg uptake is well documented for other crops, this phenomenon has not been widely recognised in sugarcane, and is not taken into account when making Ca and Mg recommendations. The interactions between K, Ca and Mg were therefore investigated on two contrasting soil types (Oxisol and Inceptisol) on the east coast of KwaZulu-Natal, South Africa, in factorial-designed field trials. Trials at each site included the plant crop (first crop after planting) and two ratoon crops (crops which regrow following harvest). This paper deals with the impact of the treatments on leaf nutrient levels and crop yields. Potassium treatments (0, 100, 200 and 300 kg K ha⁻¹, as KCl) resulted in significant (P <.001) increases in leaf K concentrations, along with relatively consistent increases in sugarcane and sucrose yields with increasing leaf K. Increased leaf K concentrations led to decreases in leaf calcium (Ca) and magnesium (Mg). Calcium silicate products Calmasil® (a calcium silicate slag) and blast furnace cement, applied at rates to supply 0 and 300 kg Si ha⁻¹, also supplied large amounts of Ca and Mg. Application of these products resulted, at times, in increased leaf Ca and Mg. Silicate application increased sugarcane and sucrose yields in three out of the four ratoon crops under study. Despite recorded increases in leaf Ca and Mg, leaf K was not decreased by silicate application on the Oxisol, and seldom so on the Inceptisol. It is proposed that the inhibitory effect of Ca and Mg on K uptake has historically been overestimated in sugarcane, and that the reverse effect – K suppression on Ca and Mg uptake – may have been underestimated.
A single solution reagent is described for the determination of phosphorus in sea water. It consists of an acidified solution of ammonium molybdate containing ascorbic acid and a small amount of antimony. This reagent reacts rapidly with phosphate ion yielding a blue-purple compound which contains antimony and phosphorus in a 1:1 atomic ratio. The complex is very stable and obeys Beer's law up to a phosphate concentration of at least 2 μg/ml.The sensitivity of the procedure is comparable with that of the stannous chloride method. The salt error is less than 1 %.
The ability of water hyacinth (Eichhornia crassipes (Mart.) Solms.) to absorb and translocate copper (Cu), nickel (Ni) and zinc (Zn) was studied at three different aquatic environments (River Nile, agricultural drain & mixed industrial and agricultural drain). Results showed that at all the studied locations, Cu, Ni and Zn were more accumulated in water hyacinth roots; their concentrations in the roots were 2 to17 times higher than in the shoots. Trace metals accumulation in root tissues was found to be in the order of Zn > Cu > Ni. Maximum values of bioconcentration factor (BCF) for Cu, Ni and Zn in water hyacinth roots were 1344.6, 1250.0 and 22758.6 respectively, indicating that the accumulation potential of Zn by water hyacinth is higher than that for Cu and Ni. Translocation ability (TA) is the ratio between the concentration of a trace element accumulated in root tissues by that accumulated in shoot tissues; a larger ratio implies poorer translocation capability. In this study the ratio results were in the order of Ni > Cu > Zn revealing that Zn is more mobile from roots to shoots than Cu & Ni. Highest concentrations of Cu, Ni and Zn in water were recorded at the mixed industrial and agricultural drain; this was accompanied by the highest accumulation of the three metals in roots of water hyacinths collected from this drain, suggesting that metal content of water hyacinth roots can serve as good bioindicator of metal pollutaion at different aquatic environments. Based on BCF values of the three metals in plant roots, water hyacinth can be primarily utilized as a good phytoaccumulator of Zn followed by Cu then by Ni. Statistical analysis showed positive significant correlations between the trace metals concentrations in ambient water and their accumulation and bioconcentration in roots and shoots of water hyacinth plant.
Water hyacinth (Eichhornia crassipes) is an aquatic weed that has blocked many navigable water-ways in the tropics. Attempts have been made to control or erradicate it to no avail. Its capacity to produce large biomass in a short time could be explored to seek other ways of utilizing it as a biofertiliser. An evaluation of the potential of water hyacinth (WH) residue as a biofertiliser was carried out in the greenhouse using a split-plot in a Radomized Complete Block Design (RCBD) experiment with three replications of each treatment. Top soil samples taken from an Entisol, Lithic Usorthent, (S1) and an Ultisol, Typic Paleustult, (S2) constituted the main plot treatments, whereas the sub-plot treatments were control (C), inorganic fertilizer (N-P-K-Mg at the rates of 240, 60, 240 and 80 kg/ha) (F), 20 t/ha water hyacinth (WH1), WH1 + F, 40 t/ha water hyacinth (WH2), WH2 + F, WH1 + 20 t /ha rice mill waste (WH1 + RW1), WH1 + 20 t/ha poultry droppings (WH1 + PD1) and WH1 + 10 t/ha RW and 10 t/ha PD (WH1 + RW1 +PD1). All amendments were mixed with the soils and incubated for 10 days before planting. The F treatment was applied at maize planting. Data were collected on maize performance and changes in soil chemical properties.Results showed that exchangeable cations, CEC, OC, total N, available P and pH increased in the WH-amended soils relative to the controls in both S1 and S2. The more fertile S1 benefited from these amendments more than S2 and showed that maize performance during the first cropping was better on S1 than S2, whereas during the residual cropping the crop performed equally well on both soils. Lower maize dry matter yields occurred in the residual than the first cropping. Also the less fertile S2 had higher residual effect of the residues than S1. Generally, WH mixed with either PD or RW or both performed better than when used alone. These results indicate that WH has a lot of potential for use as a biofertilizer on these low-fertile, fragile, tropical soils, especially if mixed with PD or PD+RW.
Key words: Soil chemical properties; Soil fertility improvement; Maize performance; Water hyacinth residues; Poultry manure; Rice mill wastes; Nigeria.Agro-Science Vol.2(2) 2001: 44-51
Contamination of the Kafue River network in the Copperbelt, northern Zambia, was investigated using sampling and analyses of solid phases and water, speciation modeling, and multivariate statistics. Total metal contents in stream sediments show that the Kafue River and especially its tributaries downstream from the main contamination sources are highly enriched with respect to Cu and exceed the Canadian limit for freshwater sediments. Results of sequential analyses of stream sediments revealed that the amounts of Cu, Co and Mn bound to extractable/carbonate, reducible (poorly crystalline Fe- and Mn oxides and hydroxides) and oxidizable (organic matter and sulfides) fractions are higher than in the residual (Aqua Regia) fraction. Compared to Cu, Co and Mn, Fe is bound predominantly to the residual fraction. Values of pH in the Kafue River and its tributaries are alkaline in the contaminated area and concentrations of sulfate gradually increase downstream. Water balance based on sulfate indicates that inflow from the most contaminated tributaries is less than 5% of total discharge in the Kafue River. There is a significant input of Cu and Co from multiple contamination sources close to the town of Chingola, located on the Mushishima tributary, but both metals are mostly bound to suspended particles, which settle in the Kafue River. Additional contaminant sources such as the Uchi mine tailings and Nkana smelter are located in the industrial area around Kitwe, but metals released from these sources are mostly found in suspension and are attenuated efficiently. Low Fe/Cu ratios in suspension and mineralogical composition of stream sediments downstream of contaminant sources around Chingola indicate that native copper, Cu-sulfides, and Cu carbonates are present in stream sediments in addition to Cu bound to Fe(III) oxide and hydroxides. The Nkana smelter fingerprint in stream sediments is recognized by the presence of slag glass and a Cu-Fe-S intermediate solid solution (ISS). Speciation modeling suggests a possibility of precipitation of some Cu phases in the most contaminated tributaries such as the Mushishima. In the early dry period (mid-May) dissolved and suspended Cu and Co concentrations are lower than in the advanced dry period (late June). When the scale of mining and related activities in the Copperbelt is taken into account, the environmental impact of mining and related activities on the Kafue River is relatively limited due to a high neutralizing capacity of the mining wastes which control the rapid precipitation of iron oxides and hydroxides as well as adsorption and/or co-precipitation of copper, and cobalt. The high metal content in stream sediments, however, may pose a potential environmental risk during accidental acid spikes, when significant fractions of metals in sediments can be re-mobilized.
The effect of nitrogen (N) levels of the culture medium (0.5–50.5 mg N l−1 or 38–3820 mg N m−2 day−1) on net productivity and nutrient (N, phosphorus (P) and potassium (K)) storage by water hyacinth (Eichhornia crassipes (Mart.) Solms) plants was investigated using outdoor tanks. Net productivity increased with N supply rate of up to 5.5 mg N l−1 (or 416 mg N m−2 day−1); higher concentrations did not significantly increase the yield. The net productivity increased until plant tissue N content reached 16 mg N g−1 dry weight, but additional increase in tissue N content did not improve yield. However, N storage in the plant tissue increased in response to N supply rate with maximum N storage (80 g N m−2) measured in plants cultured at 50.5 mg N l−1. Plant density affected N storage in the tissue; when water hyacinths were cultured in N-limited water, plant tissue-N decreased by 75% within 4 weeks of growth. The storage of P and K in the plant tissue was increased up to 5.5 mg N l−1 and 2.5 mg N l−1 in the culture medium, respectively.
The net productivity and nutrient storage of potassium (K), nitrogen (N), and phosphorus (P) by water hyacinth (Eichhornia crassipes [Mart.] Solms) were evaluated at several K concentrations in the culture medium (between 2 and 52 mg K liter-1) using 1000-liter outdoor tanks for a period of about 4 months. Maximum plant biomass (3.1 kg (dw) m-2) was reached at culture medium K concentrations of 12-52 mg K liter-1. Potassium storage in water hyacinth tissue steadily increased at K supplies of up to 52 mg K liter-1 with a maximum tissue K content of 72 mg K g-1. Maximum N and P storage in the plant biomass was reached at K concentrations of 12 and 22 mg K liter-1, respectively; further increases in K concentration did not increase either N or P storage.
A study was conducted to investigate the mulch role of water hyacinth (Eichhornia crassipes) on soil properties of a lowland rain-fed rice farming system in north-east India. The green mulch had higher carbon and nutrient contents as compared to its compost and vermicompost forms, and so were the hemicellulose, cellulose and lignin. Significant reduction in C/N ratio from fresh water hyacinth indicated rapid N release while composting. Over all, mulching significantly (p < 0.05) increased soil C, total N, available P and K as compared to the non-mulched plots. Nonetheless, soil C was greater in the green mulch plots, followed by compost and vermicompost plots. Net N mineralization rate also followed similar patterns. Upon comparison with other aquatic weedy species, E. crassipes had 20-50% more C and 10-40% more N in its residues. Likewise, the compost prepared out of E. crassipes also seems to be of good quality as indicated by a C/N ratio less than 25, as compared to Hydrilla spp., Najas spp., Ottelia spp. and Pistia stratiotes. It is therefore suggested that recycling of water hyacinth can be an ecofriendly aquatic weed management strategy to improve soil health and nutrient redistribution through a faster turnover that can engineer sustainable agricultural production in the tropical soils.
South Africa has some of the most eutrophic aquatic systems in the world, as a result of the adoption of an unnecessarily high 1 mg l−1 phosphorus (P) standard for all water treatment works in the 1970 s. The floating aquatic macrophyte, water hyacinth (Eichhornia crassipes (Mart.) Solms (Pontederiaceae)), has taken advantage of these nutrient rich systems, becoming highly invasive and damaging. Despite the implementation of a biological control programme in South Africa, water hyacinth remains the worst aquatic weed. A meta-analysis of published and unpublished laboratory studies that investigated the combined effect of P and nitrogen (N) water nutrient concentration and control agent herbivory showed that water nutrient status was more important than herbivory in water hyacinth growth. Analysis of long-term field data collected monthly from 14 sites around South Africa between 2004 and 2005 supported these findings. Therefore the first step in any water hyacinth control programme should be to reduce the nutrient status of the water body.