Concentrations In Drainage Water Research Articles

Spatiotemporal patterns and main driving factors of drainage water quality of an arid irrigation district with shallow groundwater table.

Drainage water quality is a crucial factor reflecting the regime of agricultural non-point source pollution in irrigation districts and is closely related to land use, soil texture, cropping pattern, fertilization, and irrigation and drainage conditions. However, the response of drainage water quality to various natural and anthropogenic factors needs further exploration in irrigation districts affected by shallow groundwater table. Spatiotemporal patterns of chemical oxygen demand (COD), total phosphorus (TP), total nitrogen (TN), and ammonium nitrogen (NH4-N) were monitored and analyzed in ten agricultural drainage ditches in the arid region of China from 2011 to 2019. Spatially, water pollution in agricultural drainage ditches with small water quantity can be significantly exacerbated by urban sewage, whereas a large amount of agricultural drainage can effectively dilute the pollution of urban sewage. Severe soil salinization in the cropland increases the risk of water pollution due to easier losses of soil nutrient and organic matter. Soil salinization is a key factor in the crop distribution pattern based on the crop salt tolerance, and the maize/wheat field with a higher fertilizer application rate generally results in poorer drainage water quality. Temporally, for the agricultural drainage ditches, the monthly and annual COD, TP, TN, and NH4-N concentrations fluctuate inversely with drainage water quantity and are positively correlated with fertilizer application, among which the monthly COD concentration in drainage water has larger variation in severe salinized areas. There exist critical annual and monthly drainage amounts, above which the probabilities of higher concentrations of COD, TP, TN, and NH4-N reduce greatly.

Heavy Metal Transport in Different Drip-Irrigated Soil Types with Potato Crop

Heavy metal (HM)-polluted soil is a serious concern, especially as brackish water is widely used for irrigation purposes in water-scarce countries. In this study, the HYDRUS-2D model was used to simulate HM (copper (Cu), lead (Pb), and zinc (Zn)) transport through agricultural land cultivated with potato crops under surface drip irrigation to explore the potential groundwater contamination risk. Three soil types, namely, silty clay loam, sandy loam, and sandy soil, and two irrigation schemes, irrigation every two days (scheme A) and irrigation every four days (scheme B), were considered during the simulations. Firstly, the ability of HYDRUS-2D to simulate water flow was validated using data obtained from a full growing season of the potato crop in a lysimeter irrigated by surface drip irrigation using El-Salam Canal water, Egypt (i.e., water contaminated by HMs). Secondly, the model was calibrated for solute transport parameters. After that, the investigated simulation scenarios were executed. The results showed that HYDRUS-2D effectively simulated water flow. Moreover, a good agreement between the simulations and experimental results of HM concentrations under the calibrated solute parameters was obtained with R2 values of 0.99, 0.91, and 0.71 for Cu, Pb, and Zn concentrations, respectively. HM distribution is considerably influenced by the HMs’ adsorption isotherm. The results of the investigated scenarios reveal that soil texture has a greater impact on HM concentrations in the simulation domain and on the contamination risk of the groundwater than the irrigation scheme. Under both irrigation schemes, lower HM concentrations were observed in sand, while higher values were observed in silty clay loam. Subsequently, the potential shallow groundwater contamination risk is greater when cultivating potatoes in sand, as higher HM concentrations were found in drainage water compared to the two other investigated soils, regardless of the irrigation scheme. The cumulative Cu, Pb, and Zn concentrations in drainage water corresponding to scheme A for silty clay loam and sandy loam were 1.65, 1.67, and 1.67 and 1.15, 1.14, and 1.15 times higher, respectively, than scheme B. To safeguard the sustainability of groundwater and agricultural lands irrigated with water contaminated by HMs, it is recommended to adopt an irrigation frequency of once every four days in soils with silty clay loam and sandy loam textures.

Nitrogen leaching and groundwater N contamination risk in saffron/wheat intercropping under different irrigation and soil fertilizers regimes

The ever-rising trend of nitrate leaching from the agricultural production systems is a major risk to the contamination of ground- and surface-waters and should be addressed. But so far, there has been no study on the reduction of nitrate leaching from saffron fields through intercropping. Saffron growers can make a sustainable use of the saffron inter-row spaces through the strategy of winter-wheat/saffron base intercropping system to reduce nitrate leaching. During four years of study, in a set of lysimeters, effects of two cropping systems (saffron mono-cropping and saffron–wheat intercropping), application of two sources of nitrogen (organic cow manure and chemical granular urea) and four irrigation regimes [40, 60, 80, and 100% of the standard crop evapotranspiration (ETc)] on plant nitrogen and phosphorus uptake, nitrogen leaching and nitrogen and phosphorus efficiencies were investigated. The optimum irrigation regime was experienced at 60% ETc (with irrigation application efficiency of 60%, equivalent to 100%ETc) where the highest saffron and wheat nutrient (nitrogen and phosphorus) uptake, nutrient (nitrogen and phosphorus) harvest indices, nutrient acquisition and use efficiencies, corm, saffron, and grain yields and lowest nitrogen loss was achieved. Moreover, manure application indicated 12, 42, 50 and 46% lower amounts of drained water, leachate nitrate nitrogen concentration, total leached nitrogen and N losses (other than N leaching), respectively, in comparison to the urea source of nitrogen showing the lower risk of groundwater nitrate pollution. Manure application showed 9, 8 and 9% increase in the concentration of corm nitrogen, phosphorus and protein, respectively, in comparison to urea application treatment. Saffron corm and stigma yields, irrigation and economic water productivities, corm nitrogen use efficiency and saffron-plant-nitrogen-acquisition efficiency in manure application surpassed respectively by 21, 25, 20, 17, 39 and 49% compared with the chemical source of nitrogen. Intercropping showed 10, 11, 23 and 64% lower amounts of drained water, nitrate concentration in drainage water, seasonal leached nitrate and N losses (other than N leaching), respectively compared to saffron sole cropping which reduces the risk of groundwaters nitrate contamination. For all the experimental treatments, empirical regression models were derived for estimation of seasonal leached nitrate based on the seasonal drained water. Intercropping saffron with winter wheat, application of organic cow manure and adopting irrigation regime of 60% ETc is an innovative system of saffron production which mitigates the risk of groundwater nitrate contamination and increases irrigation and economic water productivities. Saffron growers can make sustainable and clean use of the inter-row spaces of the saffron crop to grow winter wheat in order to obtain higher economic water productivity and lower groundwater nitrate pollution, and it is highly recommended to maintain a sustainable environment.

Mitigating phosphorus leaching from a clay loam through structure liming

ABSTRACT Phosphorus (P) losses from clay soils can be mitigated by introducing measures for improving soil structure. These include structure liming, where a mixture of CaO or Ca(OH)2 and CaCO3 is added to the soil. In a field experiment with separately tile-drained plots on a clay loam in Sweden, we examined the effects of structure liming on leaching of total-P, phosphate P (PO4-P) and total nitrogen (N) during three years after initial application. The treatments included two application rates (8 and 16 t ha−1) of a common product in comparison with a control (no lime). Effects of structure liming emerged during the second and third year after application, with 45 and 38% lower total-P leaching than in the unlimed control. A significant effect of the application rate was found in the third year. Nitrogen leaching and crop yield were not affected. As expected, soil pH raised following structure lime addition. Measurements of aggregate stability did not confirm the reduction in P leaching, indicating that it is important to measure P concentrations in drainage water directly when assessing the effect of structure liming.

Response of Wheat Crop to Biofertilizer Combined with Chemical Fertilizer Under Salinity Stress

This study was done to evaluated the PGPMs (Rhizobium ciceri CP-93 + Azospirillum brasilense + Trichoderma harzianum. + Pseudomonas fluorescence + Bacillus megaterium) + 25% chemical fertilizer under salinity stress for four levels. S0 ((2.7 − 3.4) dS/m, S1(4.5 − 5), S2 (7 − 9) and S3 (10 − 15) dS/m. Field and laboratory experiments were carried out in the plant protection directorate/ministry of agriculture/Abu-ghreeb/Baghdad. In 2018 - 2019, using IPA 99 wheat cultivar. laboratory Experiment demonstrated, the ability of the microorganisms used in this study, to growth and survive normally and similar to the control treatment under salinity stress in vitro for three concentration of drainage water (5, 10, 15) dS/cm. Results of field experiment showed, T6 (Rhizobium ciceri CP-93 + Azospirillum brasilense + Trichoderma harzianum. + Pseudomonas fluorescence + Bacillus megaterium + 25% chemical fertilizer) and T4(Rhizobium ciceri CP-93 + Azospirillum brasilense + Pseudomonas fluorescence + Bacillus megaterium +25% chemical fertilizer) recorded significant increased in the number of spike, number of spikletes, number of tillers and length of spike in the S1 and S2, comparison with other treatments. T6 recorded significant increase in the weight of 1000 seed in both S1 and S2 with (38.5, 38) g respectively, and in the yield of crop of one meter T6 and T4 recorded significant increase over other treatments, with 435 g/m2 and 421 g/m2 respectively in S1and (335, 330) g/m2 in S2.T6 also recorded significant increase in harvest index in both levels 27.23 % in S1 and 26 % in S2. results also showed there were no seed germination in S3, and there are not any data had been taken.

Prediction of soil solution concentrations and leaching losses of cadmium in agricultural soils.

Cadmium (Cd) leaching is often estimated in Cd balance models using the product of drainage water (precipitation excess) and soil solution Cd concentration. However, Cd concentrations are seldom available but rather predicted using empirical models. Despite the availability of empirical models that estimate soil solution Cd concentrations, they have limitations for use in New Zealand where total Cd in agricultural soils is low and organic matter (OM) high. This study derived a Freundlich-type model from desorption data and a soil-liquid partitioning coefficient (KD ) model based on sorption data to predict soil solution Cd concentrations from commonly measured soil parameters that could be used to calculate Cd leaching fluxes. Independent soil solution Cd concentrations and Cd fluxes measured in drainage water from field trials were used to validate the predictive capacity of the models. It was found that soil pH and OM content were the most important factors controlling soil solution Cd, along with total Cd. Both models explained 83% of the variation in measured soil solution Cd concentrations in an independent dataset. Comparisons between Cd fluxes predicted using the Freundlich-type model and measured fluxes were within 25% of each other at 6 of 19 field sites studied. However, physical and chemical nonequilibrium conditions in soils and uncertainty in measured values likely contributed to differences between predicted and measured Cd fluxes at other sites. To unravel the impact of nonequilibrium and soil physical conditions on Cd concentrations in drainage water, more data are required on Cd concentrations collected under field conditions. This will allow better validation of the approach used in Cd balance models to calculate Cd leaching from soils.

Microplastics in agricultural drainage water: A link between terrestrial and aquatic microplastic pollution

Microplastic (MP) contamination has been reported to be higher in terrestrial compared to aquatic environments. This is probably due to the fact that plastic items are mostly produced and used in terrestrial environments and have a longer residence time. However, there are several links between the terrestrial and aquatic environments. We analyzed drainage water samples from agricultural soils in the Seeland, a heavily drained agriculturally intensive area in Switzerland for its MP (>100 μm) concentration and composition. We found MP in relevant numbers (mean 10.5 ± 9.5 N L−1). The polymers were mainly PA and PE, and the size distribution showed an exponential increase with decreasing particle size. The results show considerable MP concentrations in drainage water and imply a transport of MP in soils down to the drainage pipes. Given the large areas drained both in Switzerland and globally, it is proposed that MP leaching from soil can be a significant source of MP to aquatic ecosystems. Such a contribution should be considered when dealing with MP cycling on a local to global scale.

A Test of Two Methods for Waste Rock Drainage Quality Prediction: Aqua Regia Extraction and Single-addition Net-acid Generation Test Leachate Analysis

The mobility of contaminants from mine waste can be assessed using different extraction methods. Aqua regia (AR) extraction is the most commonly used method in Finland. Another method is the analysis of leachate from net acid generation (NAG) tests, which is primarily designed for acid production potential assessment. We investigated the performance of single-addition NAG test leachate analysis and AR extraction in drainage quality prediction, using waste rock and drainage water samples from several Finnish waste rock sites. Our objective was to improve interpretation of the AR and single-addition NAG test leachate analysis results in drainage quality prediction. The AR extraction effectively reflected elements that occurred in elevated concentrations in drainage water, though it over-predicted Al, As, Cd, Co, Cu, and Ni in some circumneutral drainages, and Cr in general. The single-addition NAG test leachate analysis also performed well in assessing the mobility of contaminants including Al and Cr at acid mine drainage sites. As the contaminants tend to precipitate in neutral NAG test solution, the usability of the method in neutral mine drainage cases should be further investigated. Furthermore, the conclusions presented in this study are limited to waste rock samples collected from the surface of piles; future work will examine waste rock history, dump cores, drainage quality changes, etc. in more detail.

Phosphorus load in outdoor areas for laying hens and capacity of phosphorus retaining materials to reduce the environmental impact

This study investigated manure loads in outdoor paddocks for laying hens and the capacity of two phosphorus (P) retaining materials for reducing leaching from manure in areas with high hen density. Inventories on two commercial farms during 2 years (2017 and 2018) of the impact of hens (groups of 3000 hens) on vegetation, as a proxy for land use by hens, showed that 16–21% of outdoor area in grassland paddocks and 22–39% of area in a forest paddock were used by the hens. Sand and limestone were tested as P retention materials in areas with high manure load in a field study during the outdoor season for laying hens (May 1 to October 31 in 2018). The materials were placed on the ground (0.2 m deep bed, 3.3 m wide) outside the pop-hole in paddocks with 76 hens. The average numbers of hens outdoors were recorded at 9 am and 3 pm daily. There was no significant difference between the materials concerning distribution of hens, and they seemed not to prefer any material more than the other. When cylinders containing the spent materials were exposed to simulated rainfalls in a laboratory study, the P concentrations in drainage water were high for all materials, including a control with gravel (58–136 mg PO4-P L−1 and 130–197 mg total-P L−1). On average, 14% of manure P retained in the sand and limestone materials was leached after 100 mm of simulated rainfall. Thus, these materials may act as physical filters for P in manure, but to reduce the risk of P losses to waters during the following winter, they need to be removed from the paddocks and preferably used as potential P fertilizers on arable land.

A Full-Scale Case Study on the Leaching Process of Acid Rock Drainage in Waste Rock Piles and the Net Infiltration Through Cover Systems

The leaching process and drainage chemistry of acid rock drainage is mainly controlled by geochemical reactions and how water carries soluble reaction products in waste rock piles. This paper studied how water flows through a full-scale waste rock pile at the Equity Silver mine site in British Columbia, Canada and elaborated on their effects on the leaching process and drainage chemistry. A revised dual-permeability model coupled with mass transport was adopted to investigate preferential flow and matrix flow in the pile simultaneously while considering water and geochemical products leaching/exchange between them. Furthermore, a particle-level water film model and also the effects of air flow, oxygen transport, and heat transfer in pile scale were integrated to account for geochemical reactions. Simulation results of full-scale iron discharge showed that aqueous concentrations in drainage water did not vary significantly relative to variations in drainage flow rate, which was confirmed by 12 years of field monitoring data. In addition, the comparison of pre- and post-cover simulations with measured lime consumption during ARD treatment, and mass-balance/dilution calculations for the entire pile, indicates that roughly 15–20% of total precipitation passes through the cover.

An Efficacy Assessment of Phosphate Removal from Drainage Waters by Modified Reactive Material.

Phosphates may pose a threat to the aquatic ecosystem when there is a connection or a path between the soil and the aquatic ecosystem. Runoff and drainage ditches connect arable land with the waters of the receiver. Phosphates in the runoff and the ditches contribute to the negative phenomenon of surface water eutrophication. In order to prevent it, certain reactive materials are used which are capable of the selective removal of compounds by way of sorption or precipitation. Zeolites can be distinguished among the many reactive materials. Within the present analysis, the modification of a reactive material containing zeolites was carried out using calcium hydroxide solutions of different concentrations. A certain concentration of calcium hydroxide was created for use in further studies. In order to characterise the new material, an analysis was done of the chemical and mineral composition, as well as the porous texture and morphology. The efficacy of phosphate removal for its typical concentrations in drainage waters in Poland was confirmed by way of an experiment. Using a modified reactive material as an element of landscape structures may reduce the negative impact of phosphates on the quality of surface water.

Parameter sensitivity of SWAP–PEARL models for pesticide leaching in macroporous soils

AbstractPesticide transport simulation by SWAP–PEARL (Soil–Water–Atmosphere–Plant and Pesticide Emission Assessment at Regional and Local scales) models can help to predict pesticide leaching at regional scales. For reasons of economic and time efficiency, measurement efforts should be prioritized towards critical parameters. The objective of this research is to perform a Morris screening and Sobol–Jansen sensitivity analysis to SWAP–PEARL models, using a reasonable worst‐case scenario. Three pesticide compounds were analyzed:, bentazon (zero sorption), imidacloprid (moderately sorbed), and compound I (highly sorbed). Initial macropore and pesticide parameter values were varied by ±20% to generate parameter ranges. The outputs analyzed were the concentration in drainage water, the average concentration in groundwater between 1 and 2 m, and the concentration in the soil system at 100‐cm depth. Influential parameters found through the Morris method were analyzed using the Sobol–Jansen method. The results for bentazon indicate that the degradation half‐life (DT50), the bottom depth of the internal catchment (zic), and the proportion of the internal catchment at the soil surface (pic_0) are critical parameters in all the outputs analyzed. For imidacloprid and compound I, the most relevant parameters for drainage output are the Freundlich sorption exponent (Fexp) and zic; for groundwater, the relevant parameters are Fexp, the bottom depth of static macropores (zst), and pic_0; and for soil concentrations at 100‐cm depth, the relevant parameters are Fexp, zic, and pic_0. The Morris and Sobol–Jansen methods produce the same results for the first position in the ranking. Measurement efforts should be performed to update national soil databases, including critical pesticide and macropore parameters.

Nitrate leaching reduced with Dynamic‐Adaptive nitrogen management under contrasting soils and tillage

AbstractLarge temporal and spatial variability in soil nitrogen availability combined with economic risk avoidance leads many farmers across the United States to generally over‐apply N fertilizers in corn (Zea mays L.) production systems. Various static N rate calculators are promoted in the United States, but new dynamic model‐based decision tools allow for adaptive recommendations that account for specific production environments and weather. This field study quantified N leaching losses from a crossed design involving two tillage practices, plow and no‐till, and two N management tools: (i) the Corn N Calculator (CNC), a generalized static N tool for New York State, and (ii) Adapt‐N, a model‐based tool that uses soil, crop and management information with real‐time weather data. Corn was grown for four growing seasons on lysimeter plots on clay loam and loamy sand soil, and drain water samples were collected on 14 dates. Adapt‐N and CNC showed identical yields despite an overall higher N input of 66 kg ha−1 (46%) for CNC. Concentrations of NO3+NO2 in drainage water varied by sampling date, but overall were impacted by soil type (loamy sand > clay loam) and N tool, with CNC‐associated N losses 58 and 68% higher than Adapt‐N for the clay loam and loamy sand, respectively. Plow till resulted in marginally higher NO3+NO2 concentrations in drainage water than no‐till. Overall, this study offers field‐based evidence on the agronomic and environmental benefits from N management that is adapted to growing environments (soil, management, weather).

Effects of cover crops sown in autumn on N and P leaching

AbstractA field experiment with separately tile‐drained plots was used to study the ability of oilseed radish (Rhaphanus sativus L.), as a cover crop sown after harvest of a main crop of cereals or peas, to reduce nitrogen (N) and phosphorus (P) leaching losses from a clay loam in southern Sweden over 6 years. In addition to oilseed radish in pure stand, two cover crop mixtures (hairy vetch (Vicia villosa) and rye (Secale cereale) for 3 years and oilseed radish in mixture with buckwheat (Fagopyrum esculentum) for 2 years) were tested. The cover crop plots (three replicates per treatment) were compared with unplanted plots as a control. Plots cropped with oilseed radish during autumn (August–November) had significantly smaller yearly mean N concentration in drainage water over 5 of 6 years compared with unplanted controls. Mineral N content in the soil profile in autumn was significantly less in oilseed radish plots than for control plots in all years. The cover crop mixtures of hairy vetch and rye or buckwheat and oilseed radish also showed the potential to reduce soil mineral N in autumn and N concentration in drainage water, compared with unplanted controls. The cover crops had no impact on P leaching. In conclusion, oilseed radish has the ability to reduce leaching losses of N, without increasing the risk of P leaching.

An integrated assessment of nitrogen source, transformation and fate within an intensive dairy system to inform management change.

From an environmental perspective optimised dairy systems, which follow current regulations, still have low nitrogen (N) use efficiency, high N surplus (kg N ha-1) and enable ad-hoc delivery of direct and indirect reactive N losses to water and the atmosphere. The objective of the present study was to divide an intensive dairy farm into N attenuation capacity areas based on this ad-hoc delivery. Historical and current spatial and temporal multi-level datasets (stable isotope and dissolved gas) were combined and interpreted. Results showed that the farm had four distinct attenuation areas: high N attenuation: characterised by ammonium-N (NH4+-N) below 0.23 mg NH4+-N l-1 and nitrate (NO3--N) below 5.65 mg NO3--N l-1 in surface, drainage and groundwater, located on imperfectly to moderately-well drained soils with high denitrification potential and low nitrous oxide (N2O) emissions (av. 0.0032 mg N2O-N l-1); moderate N attenuation: characterised by low NO3--N concentration in drainage water but high N2O production (0.0317 mg N2O-N l-1) and denitrification potential lower than group 1 (av. δ15N-NO3-: 16.4‰, av. δ18O-NO3-: 9.2‰), on well to moderately drained soils; low N attenuation—area 1: characterised by high NO3--N (av. 6.90 mg NO3--N l-1) in drainage water from well to moderately-well drained soils, with low denitrification potential (av. δ15N-NO3-: 9.5‰, av. δ18O-NO3-: 5.9‰) and high N2O emissions (0.0319 mg N2O l-1); and low N attenuation—area 2: characterised by high NH4+-N (av. 3.93 mg NH4+-N l-1 and high N2O emissions (av. 0.0521 mg N2O l-1) from well to imperfectly drained soil. N loads on site should be moved away from low attenuation areas and emissions to air and water should be assessed.

Development of Methods to Evaluate Several Levels of Uranium Concentrations in Drainage Water Using Total Reflection X-Ray Fluorescence Technique.

As a country's law stipulates the effluent standard uranium concentration in drainage water, the uranium concentration must be determined when drainage water is released from a uranium handling facility, such as the Fukushima Daiichi nuclear power plant. The maximum allowable limit for uranium release at each facility is defined taking into consideration the situation of the facility, such as 1/10 to 1/100 of this effluent standard value. Currently, the uranium concentration of drainage water is commonly determined by α-particle spectrometry, in which several liters of drainage water must be evaporated, requiring about half of a day followed by 2–3 h of measurements, due to the low specific radioactivity of uranium. This work proposes a new methodology for the rapid and simple measurement of several levels of uranium in drainage water by a total reflection X-ray fluorescence (TXRF) analysis. Using a portable device for TXRF measurements was found to enable measurements with 1/10 the sensitivity of the effluent standard value by 10 times condensation of the uranium-containing sample solution; a benchtop device is useful to measure uranium concentrations <1/100 of the effluent standard value. Therefore, the selective usage of methods by a portable and benchtop devices allows for screening and precise evaluation of uranium concentrations in drainage water.

Phosphorus Budget for a Forested-Agricultural Watershed in Korea

Despite increased attention to the need for sustainable agriculture, fertilizer application rates above crop requirements remain common agricultural practices in South Korea, causing eutrophication of freshwater and coastal ecosystems. The aim of this study is to quantify phosphorus (P) inputs, outputs, and retention in a forested-agricultural watershed. The P budget showed that the combined use of chemical fertilizer and organic compost was the largest source of P (97.6% of the total) followed by atmospheric wet deposition (2.1% of the total P), whereas forest export (0.2% of the total) and sewage treatment plants (STPs) (0.1% of the total) were negligible. The P outputs were crop harvesting and hydrologic export to surface water. The P balance showed that P inputs are higher than the P outputs; approximately 87% of the total P input was retained in the soils within the watershed. However, P concentrations in drainage water were still high enough to cause eutrophication of downstream reservoirs. The results provide important details on the proportion of P export and retention in the watershed. This will help efforts to improve water quality and design better management strategies for agricultural nonpoint source pollution.

Modeling of contaminant transport during an urban pluvial flood event – The importance of surface flow

A Lagrangean particle based transport model is introduced to calculate the potential contamination paths of solutes in drainage water in an urban area during a pluvial flood event. The necessity to capture the complexity of a surface runoff model and the coupling of pipe and surface are investigated. Results show that fully coupled hydrodynamic models are needed for a good representation of transport paths and breakthrough curves of contaminant concentration in drainage water. An analysis for time variation of a single location spill event is performed that shows a high variability in solute spreading depending on the spill relative to the rainfall characteristics.

Transformation of the chemical composition of surface waters in the area of the exploited Lomonosov diamond deposit (NW Russia).

The specific objective of this study was to investigate the changes in the chemical composition of river waters during the exploitation of the Lomonosov diamond deposit and the danger of these changes for the ichthyofauna. It was found that the Ca-HCO3 composition of river water both upstream and downstream from the quarry was almost identical before discharge of the drainage waters into the river. In subsequent years, the water downstream from the quarry acquired a Na-HCO3 composition, and then a Na-HCO3-Cl composition and TDS increased by 2.5 times. With respect to Fe, Mn, and Mo, concentrations that are above the maximum permissible concentrations (MPCs) for fishery rivers are apparent. At the same time, elevated Fe and Mn concentrations are associated with the natural composition of river water. The negative influence of drainage waters is manifested only with respect to the high concentrations of Mo. An important role in increasing Mo concentrations in drainage waters is played by the processes of hydrolysis of sodium aluminosilicates and mixing of fresh water with salt water. The concentrations of Sr, B, Ba, V, and Cr in drainage waters are higher than those in surface waters. However, they generally do not exceed the concentrations of the current MPCs. The source of Cr, Ba, Ni, and V in the drainage waters can be the products of the kimberlite magmatism. The possible impacts of metals effects on fish are presented.

Conversion of tropical forests to smallholder rubber and oil palm plantations impacts nutrient leaching losses and nutrient retention efficiency in highly weathered soils

Abstract. Conversion of forest to rubber and oil palm plantations is widespread in Sumatra, Indonesia, and it is largely unknown how such land-use conversion affects nutrient leaching losses. Our study aimed to quantify nutrient leaching and nutrient retention efficiency in the soil after land-use conversion to smallholder rubber and oil palm plantations. In Jambi province, Indonesia, we selected two landscapes on highly weathered Acrisol soils that mainly differed in texture: loam and clay. Within each soil type, we compared two reference land uses, lowland forest and jungle rubber (defined as rubber trees interspersed in secondary forest), with two converted land uses: smallholder rubber and oil palm plantations. Within each soil type, the first three land uses were represented by 4 replicate sites and the oil palm by three sites, totaling 30 sites. We measured leaching losses using suction cup lysimeters sampled biweekly to monthly from February to December 2013. Forests and jungle rubber had low solute concentrations in drainage water, suggesting low internal inputs of rock-derived nutrients and efficient internal cycling of nutrients. These reference land uses on the clay Acrisol soils had lower leaching of dissolved N and base cations (P= 0.01–0.06) and higher N and base cation retention efficiency (P &lt; 0.01–0.07) than those on the loam Acrisols. In the converted land uses, particularly on the loam Acrisol, the fertilized area of oil palm plantations showed higher leaching of dissolved N, organic C, and base cations (P &lt; 0.01–0.08) and lower N and base cation retention efficiency compared to all the other land uses (P &lt; 0.01–0.06). The unfertilized rubber plantations, particularly on the loam Acrisol, showed lower leaching of dissolved P (P=0.08) and organic C (P &lt; 0.01) compared to forest or jungle rubber, reflecting decreases in soil P stocks and C inputs to the soil. Our results suggest that land-use conversion to rubber and oil palm causes disruption of initially efficient nutrient cycling, which decreases nutrient availability. Over time, smallholders will likely be increasingly reliant on fertilization, with the risk of diminishing water quality due to increased nutrient leaching. Thus, there is a need to develop management practices to minimize leaching while sustaining productivity.