Effects of salinity on embryonic and larval development of Chinese mitten crab Eriocheir sinensis(Decapoda: Brachyura) and salinity-induced physiological changes

To investigate the effects of salinity on early development of Chinese mitten crab ( Eriocheir sinensis ), and the salinity tolerance mechanism of embryos, different developmental stages of embryos (gastrula, eyespot and pre-hatching stage), and hatched stage I zoea and megalopa, were exposed to a range of salinities (1, 5, 10, 15 (control), 20, 25, 30, 35 and 40). Hatching, survival and molting were monitored. Effects of 24-hour hypersaline (35) and hyposaline (1) stress on egg diameter, water content, Na +/K +-ATPase (NKA) activity, and crustacean hyperglycemic hormone (CHH) gene mRNA expression in embryos and megalopa, are reported. Embryos are more tolerant of low (≤ 5) than high (≥25) salinities, with optimum ranges for gastrula and pre-hatching stage embryos being 5-20, and for eyespot embryo and stage I zoea, 10-20. Most megalopa can molt to the first juvenile instar by day 5 at salinities between 1 and 40, whereas molting of megalopa stages was delayed at 40. Hypersaline conditions resulted in a loss of moisture, reduction of egg volume, and a signifi cant increase in NKA activity and CHH mRNA expression at some developmental stages. Hyposaline conditions did not affect moisture content or egg volume, but resulted in decreased NKA activity and CHH mRNA expression in embryos. For megalopa stages, NKA activity was significantly upregulated following both hypo- and hypersaline stress. Our results suggest high salinity will inhibit development and hatching of E. sinensis embryos, and low salinity will affect the survival of their stage I zoea. Increased NKA activity in embryos and megalopa stages might indicate a hyporegulation response under hypersaline conditions. These findings provide useful information for spawning ground protection of indigenous E . sinensis and enrich the knowledge of embryonic tolerance mechanisms of hyperregulating crustaceans following osmotic stress.     

盐度渐变对黄条鰤消化酶和超氧化物歧化酶活力及甲状腺激素的影响

为探讨黄条鰤(Seriola aureovittata)对盐度渐变的应激响应机制,设置盐度5、10、15、20、29和35共6个盐度渐变点,对幼鱼的消化酶活力、超氧化物歧化酶(SOD)和甲状腺激素(T4)等生理指标进行了检测和分析。研究显示:胃、肠、肝脏和幽门盲囊的脂肪酶的活性均在盐度29渐变点最高,在低盐度渐变点这4个组织的脂肪酶活性均随盐度降低而降低。肠和肝脏的蛋白酶活性在盐度29渐变点达到峰值,幽门盲囊的蛋白酶活性则在盐度35渐变点最高,且与其他盐度渐变点间有显著性差异(P<0.05)。胃、肠、肝脏的淀粉酶活性在盐度29渐变点最高,而幽门盲囊的淀粉酶活性在盐度35渐变点最高,但与盐度29渐变点无显著性差异(P>0.05)。血清SOD活性在盐度5渐变点显著低于其他盐度渐变点(P<0.05),SOD活性在盐度20和35渐变点与29渐变点无显著性差异(P>0.05)。血清T4浓度随着盐度的升高或降低均升高,盐度20渐变点与29渐变点的T4浓度无显著性差异(P>0.05)。研究显示,自然海水盐度29是黄条鰤幼鱼存活的适宜盐度,且黄条鰤幼鱼能较快适应略低盐度(20~29),但较低或较高盐度渐变点的消化酶活力和抗应激指标则显著异常。盐度渐变可引起黄条鰤幼鱼的消化生理、抗氧化水平和T4浓度的变化,黄条鰤幼鱼对外界盐度变化表现出较强的适应性。     

不同盐度和培育密度对杂交刺参幼体生长发育的影响

分析了6个不同盐度和5个培育密度对中国刺参和日本红刺参(Apostichopus japonicus)杂交幼体的生长、存活和附着的影响。盐度实验结果显示,受精后第5天,30和35盐度组幼体成活率最高,分别为46.7%和40.0%。第2天至第5天,30盐度组耳状幼体的生长最快,到第5天平均体长达到最大值672.18μm;30盐度组的幼体附着率最高,为17.8%,而15和20盐度组中均没有出现附着的稚参。培育密度实验结果显示,受精后第5天,0.1个/mL密度组的幼体成活率最高,为66.7%,但各密度组的幼体成活率差异均不显著。0.5个/mL密度组幼体生长最快,到第10天达到最大平均体长,为801.38μm;在所有培育密度实验组中,0.5个/mL密度组的幼体附着率最高,为19.1%。因此,为实现单位水体的苗种产量最大化,刺参杂交幼体培育的最佳盐度为30,最适宜的培育密度为0.5个/mL。     

急性盐度胁迫对卵形鲳鲹幼鱼Na~+-K~+-ATP酶活性和渗透压的影响

研究了水环境急性盐度胁迫对卵形鲳鲹(Trachinotus ovatus)幼鱼鳃Na+-K+-ATP(NKA)酶活力,血清、鳃丝和肾脏渗透压的影响.结果表明:将幼鱼从盐度30(对照)中直接转移至盐度5、10、15、20、25、35水体中,96 h后无死亡.各盐度处理组的鳃NKA酶活性和血清渗透压在最初72 h内出现一定波动,随后变化平稳.试验结束时(96 h),NKA活性随盐度梯度呈"U"型分布,盐度35处理的酶活高于其他处理,盐度20处理活性最低.各处理的血清渗透压大小在96 h时,随着盐度的变化,以盐度15、20为中心,呈对称变化,在盐度20后随盐度上升呈先上升后下降的趋势.相同盐度的鳃渗透压随时间变化呈先上升后下降逐渐稳定的趋势.肾渗透压除盐度5、10处理外,其他盐度组随时间没有显著变化,维持一定的稳定性.说明卵形鲳鲹幼鱼在生理上具有广盐性鱼类的"高渗环境高NKA活性"特征,有较强的渗透压调节与平衡能力.     

Influence of combined changes in salinity and copper modulation on growth and copper uptake in the tropical green macroalga Ulva reticulata

The influence of salinity on growth and Cu uptake in the green macroalga Ulva reticulata collected from the intertidal area in the Western Indian Ocean was studied under controlled laboratory conditions. Exposure concentrations ranged from 5 to 500 μg Cu l⁻¹ at five salinities (ranging 20–40). The accumulation of Cu increased with decreasing salinity, so that the uptake at 500 μg Cu l⁻¹ was approximately 2.7, 2.4 and 2.0 times higher at salinities of 20, 25, and 30 respectively, than uptake at salinity of 35, and with uptake being lowest at salinity of 40. Ulva maintained a positive growth rate over the whole salinity range (20–40), with highest rates at salinity of 35. When exposing to Cu at low salinities (20 and 25), the growth rate of Ulva was strongly inhibited suggesting an increase in toxicity of Cu with decreasing salinity. EC50 and NOEC increased with increase in salinity, implying a reduced Cu toxicity at high salinities. It was concluded that salinity needs to be considered when using macroalgae, such as U. reticulata, as a bioindicator of heavy metals in areas with heavy rainfall, underground fresh water intrusion or in estuaries, as they might accumulate more metals and be more negatively affected.     

Seasonal variance of salinity tolerance of a copepod Drepanopus bispinosus in an Antarctic littoral saline lake (Burton Lake)

In Burton Lake (an Antarctic littoral saline lake), as one of the overwinter species, the female Drepanopus bispinosus reach adult form in autumn. and early winter.For the subsequent life period of more than eight months, the animals experience such changing environment as increasing salinities from approximately 33 (in May) to 39 (in November). There is a considerable difference of salinity tolerance of female adults between summer and winter populations.Winter collected copepods survived lower salinities than summer collected copepods in this experiment. The upward shift in their salinity tolerance range is related to the development of field acclimation to salinity. Respiration rates of the summer animals showed a visible increase over those of winter copepods in simitar salinity and temperature conditions, thus supporting the above conclusion.     

长江口及其邻近海区主要经济虾类的生态研究

本文主要取材于1985—1986年长江口渔业资源试捕调查资料。研究结果表明,分布在长江口海区的虾类,由于受长江冲淡水径流的影响,形成三种生态型:(1)河口半咸水类型,如两种白虾;(2)低盐水类型,如葛氏长臂虾;(3)外侧次高盐水类型,如鹰爪虾和两种仿对虾。代表各生态型虾类,一般具有繁殖期较长的特点,其生命周期可为一年或一年多。虾类体长分布较为复杂,在当年生的幼虾生长期间,秋冬季虾群中常有幼虾和成虾混栖。因而,种群体长分布有两组群体并存。     

盐度对日本鳗鲡生长及非特异性免疫酶活性的影响

利用实验生态学和酶学方法,在浙江省海洋水产养殖研究所清江试验场研究了盐度对平均体长为25．1±5．6cm的日本鳗鲡（Anguillajaponica）生长及其血清溶茵酶（LZM）、超氧化物歧化酶（SOD）及碱性磷酸酶（AKP）活性的影响,实验持续60d．实验设置了5个盐度梯度（盐度5、10、15、20、25）和对照组（盐度0）,每梯度设3个平行组,各组盐度和pH值保持一致．日本鳗鲡血清中免疫酶活力指标：碱性磷酸酶、溶茵酶、超氧化物歧化酶在实验的第7天和第14天测定．实验结果表明,盐度5组相对增重率最高（279．78％±28．37％）,其次是盐度10组（278．74％±22．25％）,盐度15、20、25组相对增重率分别为234．39％±21．28％、230．28％±26．31％、228．01％±29．29％．对照组相对增重率为233．20％-4-25．18％,盐度5和10组与对照组差异显著（P〈0．05）,其余各组与对照组差异不显著．第7天和第14天,盐度10组碱性磷酸酶活性最高,分别为225．05U／dm。和251．11U／dm’,其次是盐度5组,分别为221．76U／dm。和236．01U／dm。,显著高于对照组（P〈0．05）．第7天和第14天盐度20、25组溶菌酶活性显著高于对照组（P〈0．01）．超氧化物歧化酶随着盐度的升高呈逐步上升趋势．第14天,盐度20、25纽溶菌酶活性仍保持较高水平,SOD回落至对照组水平,而各组AKP较第7天略有上升．     

Rearing in intermediate salinity enhances immunity and disease-resistance of turbot (Scophthalmus maximus L.)

Studies were conducted to investigate the non-specific immune responses and disease-resistance of juvenile turbot Scophthalmus maximus,cultured at four different salinities(8,20,32 and 40) . Three concentrations(3.75 × 10 7,3.75 × 10 8 and 3.75 × 10 9 CFU/ml) of Vibrio anguillarum suspension were employed at each salinity to determine the 4-day LD 50 . The serum lysozyme activity,the alternative complement pathway activity(ACH50) and the phagocytosis percentage of head kidney in turbot were tested at 24,48 and 72 h post-challenge of V. anguillarum(1.1 × 10 8 CFU/ml,0.1 ml) ,respectively,to evaluate the non-specific immune responses at the selected rearing salinities. Fish reared at salinity 20 had the lowest mortality,namely,the highest 4-day LD 50 value(8.88 ± 0.17) . Besides,the lysozyme activity,ACH50 and the phagocytosis of turbot were the highest at the salinity 20,but with the lowest at the salinity 40 treatment regardless of sampling time. In addition,the non-specific immune activities kept increasing within 72 h post-challenge of V. anguillarum,except that the lysozyme activity increased from 24 to 48 h,and then decreased from 48 to 72 h at 40 significantly. These results together indicate that rearing in intermediate salinity(20) was able to enhance the immunity and disease-resistance of turbot.     

Effects of various pollutant mixtures on immune responses of the blue mussel (Mytilus edulis) collected at a salinity gradient in Danish coastal waters

The Baltic Sea is a semi-enclosed sea with a steady salinity gradient (3‰–30‰). Organisms have adapted to such low salinities, but are suspected to be more susceptible to stress. Within the frame of the integrated environmental monitoring BONUS + project “BEAST” the applicability of immune responses of the blue mussel was investigated in Danish coastal waters. The sampling sites were characterised by a salinity range (11–19‰) and different mixtures of contaminants (metals, PAHs and POPs), according to chemical analysis of mussel tissues. Variation partitioning (redundancy analysis) was applied to decompose salinity and contamination effects. The results indicated that cellular immune responses (total and differential haemocyte count, phagocytic activity and apoptosis) were mainly influenced by contaminants, whereas humoral factors (haemolytic activity) were mainly impacted by salinity. Hence, cellular immune functions may be suitable as biomarkers in monitoring programmes for the Baltic Sea and other geographic regions with salinity variances of the studied range.     

Environmental tolerance of Caprella mutica: implications for its distribution as a marine non-native species

Physiological tolerances limit the distribution of marine species, with geographical ranges being set by environmental factors, such as temperature and salinity, which affect the rates of vital processes and survival of marine ectotherms. The physiological tolerances of the non-native marine amphipod Caprella mutica were investigated in laboratory experiments. Adult C. mutica were collected from a fish farm on the west coast of Scotland and exposed to a range of temperatures and salinities for 48 h. C. mutica were tolerant of a broad range of temperature and salinity conditions, with 100% mortality at 30 degrees C (48 h LT50, 28.3+/-0.4 degrees C), and salinities lower than 16 (48 h LC50, 18.7+/-0.2). Although lethargic at low temperatures (2 degrees C), no mortality was observed, and the species is known to survive at temperatures as low as -1.8 degrees C. The upper LC(50) was greater than the highest salinity tested (40), thus it is unlikely that salinity will limit the distribution of C. mutica in open coastal waters. However, the species will be excluded from brackish water environments such as the heads of sea lochs or estuaries. The physiological tolerances of C. mutica are beyond the physical conditions experienced in its native or introduced range and are thus unlikely to be the primary factors limiting its present distribution and future spread.     

盐度对中国鲎幼鲎生长、蜕壳、Na+-K+-ATP酶活性、免疫指标和抗氧化能力的影响

人工增殖放流是恢复鲎资源最有效、最迅速的方法, 而了解和掌握环境因子对中国鲎(Tachypleus tridentatus)幼鲎生长状况的影响规律, 进而选择适宜放流的时间和海区, 是保证人工放流得以成功的关键。本文在实验室条件下, 研究了不同盐度(5‰、10‰、15‰、20‰、25‰、30‰、35‰、40‰)对中国鲎幼鲎成活率、蜕壳率、蜕壳增重率、Na⁺-K⁺-ATP酶活性、免疫酶活性、抗氧化酶活性等的影响, 探讨了不同盐度水平下中国鲎幼鲎生长、蜕壳、渗透调节能力、机体免疫力和抗氧化能力等的变化。养殖试验持续56d, 结果表明: 不同盐度对中国鲎幼鲎的成活率、蜕壳率、二龄幼鲎均重及蜕壳增重率均有显著影响(P<0.05), 且均随盐度升高呈先升高后降低的趋势; 蜕壳率和蜕壳增重率与盐度的回归分析均表明, 中国鲎幼鲎蜕壳与生长的最适盐度分别为24.10‰和24.94‰; 一龄和二龄幼鲎的Na⁺-K⁺-ATP酶活性均随盐度的升高呈先显著升高后显著降低趋势(P<0.05); 35‰和40‰盐度试验组一龄幼鲎的酸性磷酸酶(acid phosphatase, ACP)活性显著高于其他试验组, 而5‰盐度试验组一龄幼鲎的碱性磷酸酶(alkaline phosphatase, AKP)活性显著低于25‰试验组(P<0.05) ; 盐度对二龄幼鲎的ACP、AKP和溶菌酶(lysozyme, LZM)活性均没有显著影响(P>0.05); 35‰和40‰试验组一龄幼鲎的过氧化氢酶(catalase, CAT)活性显著高于盐度较低试验组(P<0.05); 二龄幼鲎的谷胱甘肽过氧化物酶(glutathione peroxidase)活性随着盐度的升高而升高, 盐度10‰试验组显著低于30‰和40‰试验组(P<0.05)。研究结果显示盐度对中国鲎幼鲎生长、蜕壳、Na⁺-K⁺-ATP酶活性、免疫指标和抗氧化能力均有显著影响, 蜕壳最适宜的盐度在24‰~25‰左右, 盐度过高或过低都将引起幼鲎生长率和成活率降低, 渗透调节能力、免疫力和抗氧化力显著下降。     

Impacts of Habitat Complexity on Physiology: Purple Shore Crabs Tolerate Osmotic Stress for Shelter

Purple shore crabs, Hemigrapsus nudus (Crustacea: Decapoda), can survive indefinitely in salinities of 8 (25% SW), but also tolerate short-term exposure to salinities as low as 2. In the laboratory their salinity preference range, determined from choice chamber experiments, is 22–32 and they can discriminate between pairs of salinities separated by a difference of 2. These crabs show a strong positive thigmotaxis and a weak negative phototaxis and tend to choose environments with available shelter. The presence of shelter significantly alters the behaviour of this species. When shelter is available the salinity preference range is 10–32. Even in salinities below this preference range, the presence of shelter prolongs the time spent in the lower test salinities. This change in behaviour has implications on the crab's physiology: the haemolymph osmolality falls to lower levels when crabs remain in low salinity under shelters. In the field, H. nudus is found in creeks with salinities close to freshwater and they may remain in this salinity for up to 11 h, if there are rocks under which to shelter. An increase in habitat complexity increases the number of crabs that are found within the creek. These crabs in the low salinity environment have a lower haemolymph osmolality than crabs on the nearby open shore. In H. nudus the behavioural selection of a shelter appears to outweigh the physiological costs associated with osmotic regulation of the body fluids. Therefore, the distribution of H. nudus in estuaries may depend more on the availability of suitable habitats rather than the salinity tolerance of this species.     

盐度突变对半滑舌鳎血浆渗透压和鳃丝Na+/K+-ATP酶活性的影响

研究了半滑舌鳎(Cynoglossus semilaevis)由盐度30突变至0、1O、20、35和40盐度后血浆渗透压和鳃丝Na+/K+-ATP酶活性的变化.结果表明,盐度对半滑舌鳎血液渗透压和鳃丝Na+/K+-ATP酶活性均有显著影响(P＜0.05).盐度突变后,各处理组的血液渗透压和鳃丝Na+/K+-ATP酶活性...     

温度、盐度和两种麻醉剂对大泷六线鱼幼鱼耗氧率、排氨率的影响

采用静水呼吸室法,研究了温度、盐度和两种麻醉剂(丁香油、MS-222)对体质量为(6.44±0.59)g的大泷六线鱼幼鱼耗氧率和排氨率的影响.实验分别设置了5个温度梯度(8℃、12℃、16℃、20℃、24℃),5个盐度梯度(15‰、20‰、25‰、30‰、35‰),6个丁香油浓度梯度(0、8、16、24、32、40 m...     

天津厚蟹对盐度和温度的耐受性

研究了天津厚蟹Helice tientsinensis对盐度和温度的耐受性。天津厚蟹对盐度的耐受能力极强,在温度9~34℃盐度为0的淡水介质中均能存活96h以上;在10℃、20℃及30℃的高渗介质中暴露96h后,天津厚蟹全部存活的盐度分别是65、56和50,全部死亡的盐度分别为83、74和68。天津厚蟹对低温的耐受力较强,在0、30和50盐度水平下,耐受低温的能力差别较大,能耐受96h的最低温度分别是9℃、2℃和6℃。天津厚蟹对高温也有较强的耐受能力,在0、30和50盐度水平下,分别在34℃、36℃和35℃下能耐受96h;盐度50温度38℃时,在开始的24h内无死亡,但48h后死亡率急剧上升,同样规律也出现在30和0溶液中,前者温度是39℃,后者为35℃。研究结果还表明盐度和温度的交互效应显著,二者的交互作用对天津厚蟹的存活亦有显著性影响(P0.05),温度升高(从10℃到20℃再到30℃)致使其耐盐能力显著下降,而盐度的剧烈变化(从30到50或从30到0)也致使其耐温能力显著下降。     

基于人为调控盐度的促进大叶藻种子萌发及建苗技术研究

Vast declines in Zostera marina seagrass beds demand effective methods of rehabilitation. In this study, we developed a practical method by reducing salinity to induce seed germination followed with recovering salinity to facilitate seedling production of Z. marina. The results showed that Z. marina seeds collected from natural seawater(salinity 30) were induced to germinate at reduced salinities. Percent germination(GR) was higher and mean-time-to-germinate(MTG) was shorter at lower salinities. The highest GR and shortest MTG occurred at salinity 0(deionized freshwater). After germination in freshwater, seeds could develop into seedlings at salinities5–30 and continue the growth. Viability or development of germinated seeds was not significantly different during the 40 d of post-germination incubation at salinities 5–15 after 1–20 d of germination in freshwater. However,during the process of translating germinated seeds from salinity 0 and 5 to salinity 30, reducing the gradients of post-germination acclimation facilitated more seeds forming seedlings in less time. On average, after 60 d of static incubation, including 20 d in freshwater for germination followed with immediate shift to salinity 5 and increasing to salinity 30 at increment of 5 every two days until cultivation at constant salinity 30, 33% of Z. marina seeds produced healthy seedlings. The results indicate that the salinity-manipulation based method of artificial germination and seedling production is practical and effective in supporting rehabilitation of Z. marina bed.     

山东南部近海秋季长蛇鲻相对资源量的分布及其影响因素

为探究长蛇鲻(Saurida elongate)的生态习性和分布规律,并为长蛇鲻资源的合理利用与养护提供科学依据,本文根据2016年秋季在山东南部近海进行的渔业资源与环境调查数据,分析了该海域长蛇鲻的分布特征,研究长蛇鲻成体、幼体的分布差异,并利用广义可加模型(GAM)研究其分布与生物因子和环境因子的关系。结果表明,长蛇鲻成体与幼体的分布存在差异,成体分布范围广,幼体主要分布在30 m等深线及以浅水域。GAM模型的结果表明,饵料生物、底层水温、水深和底层盐度是影响长蛇鲻相对资源量分布的主要因子。成体、幼体的分布与影响因子的关系差异极显著(P<0.01)。长蛇鲻成体的相对资源量随饵料生物和底层水温的增加表现为先上升后下降的趋势,而幼体呈现一致上升趋势;成体和幼体的相对资源量随水深增加均呈下降趋势;幼体相对资源量随底层盐度增加有明显上升趋势,而盐度对成体的影响不显著。本研究认为山东南部近海是长蛇鲻的重要栖息地,水温和盐度是成体和幼体分布差异的可能原因。     

Combined Effects of Temperature and Salinity on the Zoeal Development of the Crab Liocarcinus puber (Decapoda: Portunidae)

Abstract. Larval development of the crab Liocarcinus puber was studied from hatching to the megalopa stage under 12 different temperature and salinity combinations, 10°C, 15°C, and 20°C (T): 20, 25, 30, and 35% (S), with a view to establishing optimum conditions for zoeal development. High larval mortalities were recorded at 10°C in all the experimental salinities, indicating the sensitivity of the larvae to low temperatures. Highest zoeal survival was obtained in the higher salinity and temperature combinations. First zoeae completed their development in all T-S combinations tested, while successive stages showed increased sensitivity and suffered high mortalities in lower salinities at 15° and 20°C and in all salinities at 10°C. The duration of zoeal development decreased with increasing temperature, whilst the lower salinities delayed development. Q₁₀ values did not differ much at higher salinities, with values ranging from 1.5 to 2.6.     

239,240Pu in estuarine and shelf waters of the north-eastern United States

The distribution of ^239,240Pu between dissolved and particulate forms has been measured in four estuaries on the north-east coast of the United States (Connecticut River, Delaware Bay, Chesapeake Bay, and Mullica River). The data cover the whole salinity range from freshwater input to shelf waters at 35‰ and includes one profile from a nearly anoxic basin in the Chesapeake Bay.In the organic-rich Mullica River estuary, large-scale removal of riverine dissolved ^239,240Pu occurs at low salinities due to salt-induced coagulation, a mechanism analogous to that for iron and humic acids. Within the 0 to 25–30‰ zone in the other three estuaries, the activity of dissolved ^239,240Pu increases almost conservatively. The activities of particulate ^239,240Pu are highest in the more turbid waters of low salinity regime (0–15‰), but become increasingly insignificant with respect to dissolved ^239,240Pu as salinities increase. At higher salinities corresponding to shelf water, there is a sharp increase in dissolved ^239,240Pu activity. The dissolved ^239,240Pu activity within each estuary appears to be inversely related to the flushing time of water. For example, Chesapeake Bay has a 6–12 month flushing time and has much lower dissolved ^239,240Pu activities than does the Connecticut River Estuary which has a flushing time of a few days. This and other data from the shelf waters are interpreted as indicating that the sharp decrease in dissolved ^239,240Pu activities between shelf and estuarine waters is driven by removal within the estuaries themselves rather than on the shelf.Dissolved ^239,240Pu activities are lower in the nearly-anoxic bottom waters of Chesapeake Bay indicating enhanced removal by redox transformation of Pu [i.e., Pu(V) to Pu(IV)].