Removal and uptake of copper (II) by Salvinia natans from waste water

The plant, Salvinia natans L., was found to be very useful in the removal of Cu (II) from waste water. Maximum accumulation was noted within one day and maximum removal (about 90%) was recorded below 50 μg mL^?1 of Cu (II). Copper was successfully removed from the waste water of Hindusthan Copper Limited (HCL), ICC, Ghatsila, Bihar, India.     

Salvinia natans — as the scavenger of Hg(II)

The plant, Salvinia natans L., was found effective in the removal of Hg(H) from wastewater. Maximum accumulation was noted within a day and maximum removal (about 90%) was recorded below 5 ppm of Hg(II). Accumulation of the metal occurred mainly in the roots. The senescence of the plant started at and above 5 ppm of Hg(H). The biochemical constituents like chlorophyll, Hill-activity, Protein, RNA, dry weight, and activities of catalase and protease decreased while free amino acid content, peroxidase activity and the ratio of acid to alkaline pyrophosphatase activity increased over control values at and above 5 ppm of Hg(H).     

Studies of toxic effects of Hg(II) on Pistia stratiotes

The uptake of Hg(II) and toxicity effect of the metal on some biochemical parameters in Pistia stratiotes L. were studied. The uptake of Hg(II) by the plants gradually increased with increase in concentration of Hg(II) in the culture medium. Maximum accumulation of Hg(II) was noted within 1 day. Maximum removal (about 90%) of Hg(II) was recorded below 20 ppm Hg(II). Accumulation of Hg(II) in roots was about four times higher than that in shoots. At 20 ppm, Hg(II) promoted senescence of Pistia plants by decreasing chlorophyll, protein, RNA, dry weight and activities of catalase and protease as well as increasing free amino acid content, peroxidase activity and the ratio of acid to alkaline pyrophosphatase activity over control values. At Hg concentrations below 20 ppm, these constituents were least affected.     

Studies on the metabolism in roots of lowland rice (Part II)

In the previous paper¹⁾, we compared the in. organic composition of root with that of shoot of rice plant at successive growth stages, and revealed that the content of inorganic elements in root was generally lower than that in shoot, and that paddy root, sending most of absorbed salts to the top, does not possess a function to store inorganic nutrients.     

Evaluation of wood ash disposal on agricultural land. II. Potential toxic effects on plant growth

Abstract

Land application of wood ash is a rapidly growing disposal option for industries combusting wood for steam or electricity. Recent research has demonstrated that wood ash is a valuable soil amendment and liming agent. The objective of this study was to examine the potential phytotoxic components of wood ash and their interactive effects in order to determine appropriate land application rates.

Bush beans (cv. ‘Blue Lake 274') were grown under greenhouse conditions in an acidic Palouse silt loam soil treated with a background concentration of wood ash equivalent to 10 mt/ha (0.09 kg/ha of B, 462 kg/ha of K, and pH 6.5). The ash‐soil mixture was then amended with different concentrations of B, K, and CaO (for pH change) in a completely randomized factorial experiment.

Soil pH and K concentration appeared to be the major rate limiting components in land application of wood ash. Bean yield was adversely impacted when application rates resulted in a soil pH >6.5 and 2,662 kg K/ha. Since pH was the most important rate limiting component, ash application rates should be based on the calcium carbonate equivalent of the ash and the pH requirements of the crops.     

Studies on Selective Uptake Behavior of Hg(II) and Pb(II) by Functionalized Poly(Ethylene Terephthalate) Fiber with 4-Vinyl Pyridine/2-Hydroxyethylmethacrylate

The adsorption behavior of 4-vinyl pyridine and 2-hydroxyethylmethacrylate grafted poly(ethylene terephthalate) fiber toward the Hg(II) and Pb(II) ions in aqueous solutions was studied by a batch equilibration technique. The influence of the treatment time was considered as well as the pH of the solution, the initial metal ions concentration, the graft yield, and the temperature. Such parameters as the adsorption kinetics, the adsorption isotherm, and the desorption time were further studied. Maximum adsorption occurred at pH 3 and pH 6 for Hg(II) and Pb(II), respectively. The adsorption kinetics followed the mechanism of the pseudo-second-order equation for heavy metal ions. The adsorption data is a good fit with Freundlich isotherm. Desorption studies indicated that the maximum percent recovery of Hg(II) and Pb(II) was 93.4% and 76.3%, respectively with 1 M HNO₃.     

Aluminum effects on uptake and translocation of nitrogen in sorghum (Sorghum bicolor,L. Moench)

The effects of aluminum on the uptake and translocation of N in two hybrid cultivars of sorghum with differential tolerance to aluminum were studied.

Aluminum decreased the amount of N accumulated and the % of N in the aerial parts of the plants. In the roots the amount of N accumulated also decreased but the % of N increased, in both cultivars. Besides an effect on dry matter yield, Al probably reduces the uptake of N and its translocation to the aerial parts of the plant. Apparently, this impairment on N translocation resulted from Al effects on the root pressure.

Aluminum not only reduced the amount of N translocated but also changed the sap composition. The % of NO₃ ‐N decreased while the % of amino acid‐N increased suggesting an Al effect on N uptake and also on protein degradation. Asparagine and glutamine contributed about 80% of the free amino acid fraction; however, their proportions changed in presence of Al. Therefore, Al also interfered with the synthesis and/or interconversion of these amino acids.     

Numerical and Experimental Studies on Cadmium (II) Transport in Kaolinite Clay under Electrical Fields

A numerical model was formulated to simulate cadmium (Cd) transport under an electric field using one-dimensional diffusion-advection equations describing the contaminant transport driven by chemical and electrical gradients in kaolinite clay. The numerical model includedcomplex physicochemical factors affecting the transport phenomena, such as soil pH value, zeta potential, aqueous phase reaction, adsorption, and precipitation. One-dimensional finite-difference computer models successfully predicted meaningful values for soil pH profiles and Cd concentration profiles. To verify the results of the proposed model by comparing them with experimental results, two different types of laboratory electrokinetic tests, unenhanced and enhanced tests, were conducted. The numerical and the experimental results showed good agreement. In addition, those results indicate that soil pH is the most important factor in governing the dissolution and/or desorption of Cd in the soil system under electrical fields. The removal efficiency of Cd in the unenhanced test was low (15.6%) due to a high accumulation in the region near the cathode. On the contrary, the cadmium concentration profile of the enhanced test showed a different pattern, and most of the residual concentrations appeared below the initial level at each local point within the soil cell after processing. The removal efficiency of the enhanced test was much higher (42.7%) than that of the unenhanced test, resulting from the prevention of hydroxide precipitation near the cathode using the acidic catholyte. Consequently, the result implies that the enhancement schemes such as conditioning of catholyte should be required to increase the effectiveness of the electrokinetic technology in removing metal contaminants from soils.     

Biokinetic behavior and settling characteristics in an activated sludge under the effect of toxic Ni(II) influentes

The inhibitory effect of Ni upon a biological system of activated sludge has been analyzed in two semicontinuous sequential reactors feeding synthetic wastewater. One of the reactors was used as control while in the other given amounts of NiSO₄ were added to the influent to achieve a concentration of 30 ppm Ni(II). An analysis of the characteristic biokinetic parameters has been made and the correspondence with the operating conditions stated. A series of O₂ uptake tests were proposed and the results analyzed together with the specific rate of substrate removal (U) in order to explain the toxic influence of Ni(II). An accumulation of undigested substrate on the floes seems to explain certain aspects derived of the presence of Ni. The sludge residence time (SRT), within a certain range, can be used as a control operating variable to mitigate the inhibitory effect of Ni, since a somewhat contrary effect upon the settling characteristics of the sludge must be also considered.     

Distribution of Manganese(Ⅱ) Chemical Forms on Soybean Roots and Manganese(Ⅱ) Toxicity

Distribution of chemical forms of manganese(Ⅱ)(Mn(Ⅱ))on plant roots may affect Mn(Ⅱ)absorption by plants and toxicity of Mn(Ⅱ)to plants at its high level.The chemical forms of Mn(Ⅱ)on soybean roots were investigated to determine the main factors that affect their distribution and relationship with Mn(Ⅱ)plant toxicity.Fresh soybean roots were reacted with Mn(Ⅱ)in solutions,and Mn(Ⅱ)adsorbed on the roots was differentiated into exchangeable,complexed,and precipitated forms through sequential extraction with KNO_3,EDTA,and HCl.The exchangeable Mn(Ⅱ)content on the roots was the highest,followed by the complexed and precipitated Mn(Ⅱ)contents.Mn(Ⅱ)toxicity to the roots was greater at pH 5.5 than at pH 4.2 due to the larger amount of exchangeable Mn(Ⅱ)at higher pH.The cations Al~(3+),La~(3+),Ca~(2+),Mg~(2+),and NH_4~+competed with Mn(Ⅱ)for cation exchange sites on the root surfaces and thus reduced exchangeable Mn(Ⅱ)on the roots,in the order Al~(3+),La~(3+)Ca~(2+),Mg~(2+)NH_4~+.Al~(3+) and La~(3+) at 100μmol L~(-1) decreased exchangeable Mn(Ⅱ)by 80%and 79%,respectively,and Ca~(2+) and Mg2+at 1 mmol L~(-1) decreased exchangeable Mn(Ⅱ)by 51%and 73%,respectively.Organic anions oxalate,citrate,and malate reduced free Mn(Ⅱ)concentration in solution through formation of complexes with Mn(Ⅱ),efficiently decreasing exchangeable Mn(Ⅱ)on the roots;the decreases in exchangeable Mn(Ⅱ)on the roots were 30.9%,19.7%,and 10.9%,respectively,which was consistent with the complexing ability of these organic anions with Mn(Ⅱ).Thus,exchangeable Mn(Ⅱ)was the dominant form of Mn(Ⅱ)on the roots and responsible for Mn(Ⅱ)toxicity to plants.The coexisting cations and organic anions reduced the exchangeable Mn(Ⅱ)content,and thus they could alleviate Mn(Ⅱ)toxicity to plants on acid soils.     

Cu(Ⅱ)、Pb(Ⅱ)和Cd(Ⅱ)在红壤胶体和非胶体颗粒上吸附的比较

研究了湖南长沙和海南昆仑的2种红壤胶体和非胶体的矿物组成、阳离子交换量(CEC)及Cu(Ⅱ)、Pb(Ⅱ)和Cd(Ⅱ)在土壤胶体和非胶体颗粒表面的吸附行为,以明确红壤胶体对土壤表面化学性质的贡献。X射线衍射分析结果表明,两种红壤胶体的矿物组成均以次生矿物为主,次生矿物又以1∶1型高岭石所占比例最高。土壤非胶体颗粒中石英等原生矿物含量较高。土壤铁铝氧化物主要富集在土壤胶体部分,土壤胶体颗粒中游离氧化铁和游离氧化铝含量明显高于非胶体颗粒,如湖南长沙红壤胶体颗粒游离氧化铁的含量为78.03 g kg~(-1),而非胶体颗粒中仅为9.93 g kg~(-1)。土壤胶体颗粒的CEC显著高于非胶体颗粒部分,2种红壤胶体的CEC约为非胶体的12倍。等温吸附实验结果表明,土壤胶体颗粒对Cu(Ⅱ)、Pb(Ⅱ)与Cd(Ⅱ)的最大吸附量和吸附亲和力均显著大于非胶体颗粒,湖南红壤胶体对3种重金属的吸附量大于海南红壤胶体,与土壤胶体的矿物组成和CEC大小一致。Cd(Ⅱ)在红壤胶体和非胶体颗粒表面主要发生静电吸附,而静电吸附和非静电吸附两种机制均对Cu(Ⅱ)和Pb(Ⅱ)的吸附有重要贡献。     

冷型小麦氮素吸收积累特性的研究

2002至2004年,通过田间小区试验,研究了4种施肥条件下(不施肥、单施磷肥、单施氮肥和氮磷配施)冠层温度持续偏低的冷型小麦氮素吸收积累特性。供试小麦品种为小偃6号、陕229、NR9405和9430,前两者为冷型小麦品种,后两者为暖型小麦品种。结果表明,花前冷型小麦叶片具有较高的氮素积累量;花后氮素吸收积累量在单施磷肥、单施氮肥和氮磷配施条件下比暖型小麦分别高168.6%、144.6%和217.4%。成熟期冷型小麦子粒中氮素积累量大,功能叶片中氮素残留量多。冷型小麦叶片较高的氮素含量为维持叶片较高的光合速率奠定了良好的氮营养基础;花后氮素吸收积累量较多的特点,与冷型小麦灌浆结实期具有较高的代谢生理活性,根系吸收氮能力强有密切关系。     

Competition from Cu(II), Zn(II) and Cd(II) in Pb(II) Binding to Suwannee River Fulvic Acid

This is a study of trace metal competition in the complexation of Pb(II) by well-characterized humic substances, namely Suwannee River Fulvic Acid (SRFA) in model solutions. It was found that Cu(II) seems to compete with Pb(II) for strong binding sites of SRFA when present at the same concentration as Pb(II). However, Cd(II) and Zn(II) did not seem to compete with Pb(II) for strong binding sites of SRFA. These two metals did compete with Pb(II) for the weaker binding sites of SRFA. Heterogeneity of SRFA was found to play a crucial role in metal–SRFA interactions. The environmental significance of this research for freshwater is that even at relatively low Pb(II) loadings, the metals associated with lead in minerals, e.g. Cu(II), may successfully compete with Pb(II) for the same binding sites of the naturally occurring organic complexants, with the result that some of the Pb(II) may exist as free Pb²⁺ ions, which has been reported to be one of the toxic forms of Pb in aquatic environment.     

Aluminum effects on nitrate uptake and reduction in sorghum

The effects of Al on nitrate uptake and on the activity of the nitrate reductase (NR) in two hybrid cultivars of sorghum (Sorghum bicolor (L.) Moench) differing in Al tolerance were studied. The nitrate uptake by intact root system was strongly reduced by Al in both cultivars, but mainly in the Al‐sensitive cultivar. The kinetic constants also changed in the presence of Al: Vmax decreased 98% and 71% and Km increased 267% and 42% in the Al‐sensitive and Al‐tolerant cultivar, respectively. Aluminum reduced the in vitro NR activity on the roots and shoots of both cultivars, especially of the Al‐sensitive cultivar. Aluminum added to the nutrient solution or to the reaction mixture, however, inhibited differentially the NR of the roots and shoots, indicating marked differences between the enzymes from these two tissues. Aluminum reduced the Vmax but did not affect the Km of nitrate activation of the shoot NR. Therefore, Al inhibition of the NR was non‐competitive and could not be reversed by increasing nitrate concentration. Aluminum not only reduced the nitrate uptake but also had a direct effect on the NR and consequently on nitrate reduction. A correlation between NR tolerance to Al and plant tolerance to Al was observed.     

Subsoil compaction effects on crops in Punjab, Pakistan:II. Root growth and nutrient uptake of wheat and sorghum

Crop yields can be reduced by soil compaction due to increased resistance to root growth, and decrease in water and nutrient use efficiencies. A field experiment was conducted during 1997–1998 and 1998–1999 on a sandy clay loam (fine-loamy, mixed, hyperthermic Typic Haplargids, USDA; Luvic Yermosol, FAO) to study subsoil compaction effects on root growth, nutrient uptake and chemical composition of wheat (Triticum aestivum L.) and sorghum (Sorghum bicolor L. Moench). Soil compaction was artificially created once at the start of the study. The 0.00–0.15 m soil was manually removed with a spade. The exposed layer was compacted with a mechanical compactor from 1.65 Mg m⁻³ (control plot) to a bulk density of 1.93 Mg m⁻³ (compacted plot). The topsoil was then again replaced above the compacted subsoil and levelled. Both compacted and control plots were hoed manually and levelled. Root length density, measured at flowering stage, decreased markedly with compaction during 1997–1998 but there was little effect during 1998–1999. The reduction in nutrient uptake by wheat due to compaction of the subsoil was 12–35% for N, 17–27% for P and up to 24% for K. The reduction in nutrient uptake in sorghum due to subsoil compaction was 23% for N, 16% for P, and 12% for K. Subsoil compaction increased N content in wheat grains in 1997–1998, but there was no effect on P and K contents of grains and N and P content of wheat straw or sorghum stover. During 1997–1998, K content of wheat straw was statistically higher in control treatment compared with compacted treatment. In 1998, P-content of sorghum leaves was higher in compacted treatment than uncompacted control. Root length density of wheat below 0.15 m depth was significantly reduced and was significantly and negatively correlated with soil bulk density. Therefore, appropriate measures such as periodic chiselling, controlled traffic, conservation tillage, and incorporating of crops with deep tap root system in rotation cycle is necessary to minimize the risks of subsoil compaction.     

Effect of Copper(II), Lead(II), and Zinc(II) on Growth and Sporulation of Halophytophthora from Taiwan Mangroves

This study evaluated the effect of lead (Pb(II)), zinc (Zn(II)) and copper (Cu(II)) on growth and sporulation of four Halophytophthora species (Halophytophthora vesicula, Halophytophthora elongata, Halophytophthora spinosa var. lobata, and an oogonia-producing Halophytophthora sp.) isolated from different mangrove sites in Taiwan. Results show that all isolates grew well or even better at 1 ppm concentration of the heavy metals tested. Growth of all test isolates was totally inhibited at 500 ppm, except for H. spinosa var. lobata exposed to Zn(II). For sporulation, all isolates produced moderate to abundant zoosporangia or oogonia at 1 ppm Pb(II) and Zn(II). Production of zoosporangia by H. vesicula, H. elongata and H. spinosa var. lobata was significantly affected or totally inhibited at 1 ppm Pb(II) and Zn(II) and all concentrations of Cu(II). Abnormal oogonia were produced by Halophytophthora sp. at 10 ppm Cu(II) and 100 ppm of the three heavy metals. In general, Cu(II) and Zn(II) were found to be the most toxic, and the least toxic was Pb(II). H. spinosa var. lobata was the most tolerant to all the heavy metals, while H. vesicula and H. elongata were the most sensitive. Results of this study shows that increased concentrations of Pb(II), Cu(II), and Zn(II) in the mangrove environment can significantly affect growth and impair normal reproduction of Halophytophthora species.     

Osmotic and toxic ion effects on seedling emergence and nutrition of citrus rootstocks

The effects of isosmotic solutions of sodium chloride (NaCl), polyethylene glycol (PEG), and mannitol with or without supplemental calcium (Ca) were compared to separate osmotic effects from toxic ion effects of salts on seed imbibition, seedling emergence, and the early stage of seedling growth of three citrus rootstocks. The rate of seed imbibition was relatively low for sour orange (SO) in PEG treatments which caused a delay in seedling emergence. These results of PEG supported earlier findings which suggested the existence of a critical level of hydration that seeds must reach before germination can proceed. Final percent emergence (FPE) was reduced the most by NaCl and mannitol compared with PEG. Furthermore, Ca addition to mannitol and NaCl solutions improved FPE in Cleopatra mandarin (CM) and trifoliate orange (TO). These results demonstrated that the effects of mannitol and NaCl on FPE went beyond the osmotic effects. Seedling growth was reduced the most by mannitol not only due to its uptake and transport to the leaves and stems where it caused dehydration and visible leaf injury but also to reduction in shoot Ca and potassium (K) concentrations. This study showed that the effects of salts on seed imbibition and time to emergence of the first seedling was primarily osmotic, while their effects on FPE and seedling growth was mainly toxic.     

Studies of the availability of toxic heavy elements in soils and sediments in the vicinity of a lead smelting site (Germany)

The lead smelting site near Clausthal-Zellerfeld (Harz Mountains, Germany) was in operation for 700 years. As a result of this long operating time, the soil and stream sediments in the vicinity of the site are highly contaminated due to airborne pollution and dumping of slags. The knowledge of bulk concentrations does not give sufficient information for an estimate of the hazard potential stored in the contaminated materials. Therefore, as a first step, the element speciation in the three sample populations was determined. As the extractability (availability) of the speciations varies significantly for the different elements, a second step was used to test for the availability. The investigations on the availabilities yield a very high hazard potential for lead, followed by Cu and Zn.     

Interactive effects of chlorimuron‐ethyl and copper(II) on their sorption and desorption on two typical Chinese soils

Concern about combined pollution of agricultural ecosystems by chlorimuron‐ethyl (CHL) and copper (Cu) has increased of late, particularly in northeastern China. Sorption and desorption of CHL and Cu on soils and their interactive effects strongly affect their mobility and bioavailability. Thus, the interaction between CHL and Cu(II) with regard to their sorption and desorption on brown earth (BE, luvisols) and black soils (BS, phaeozem), two typical soils in northeastern China, was investigated by using batch experiments. The results indicated that the presence of Cu(II) increased the sorption of CHL on the two soils, which can be attributed to decreased pH in the equilibrium solution and Cu‐bridging. The formation of a Cu‐CHL complex with stronger affinity to the soils than CHL itself may be another mechanism. Addition of Cu(II) also enhanced the hysteresis effect of CHL desorption from BS but decreased that from BE. CHL at small concentrations promoted Cu(II) slightly sorption on BE and BS by the bridging effect of CHL. In addition, CHL suppressed Cu(II) desorption from the two soils, decreasing the mobility and bioavailability of Cu(II).