DDT对多刺裸腹溞的急性毒性和生命表参数的影响

采用48 h急性毒性试验研究了DDT对多刺裸腹溞的48小时LC₅₀值,采用生命表试验方法研究了暴露于不同浓度（1、8、16、24、32和40 μg·L^-1）DDT溶液中的多刺裸腹溞的生命表统计学参数.结果表明：DDT对多刺裸腹溞48小时LC₅₀值为324 μg·L^-1;浓度在1～40 μg·L^-1的 DDT对多刺裸腹溞的生命期望、净生殖率、世代时间和总繁殖率均没有显著影响(P>0.05),但对种群内禀增长率(r_m)影响显著 (P<0.05).与空白对照组相比,浓度为8、16和40 μg·L^-1的DDT显著地提高了多刺裸腹溞种群r_m.在使用多刺裸腹溞的生命表统计学参数监测亚致死浓度的DDT的生态影响时,r_m是较敏感的指标.     

龙须菜对重金属铜胁迫的生理响应

研究了大型海藻龙须菜(Gracilaria lemaneiformis)对不同浓度重金属铜(0、25、50、100、250和500 μg·L^-1)胁迫的生理响应.结果表明:当Cu²⁺浓度≥50 μg·L^-1时,龙须菜藻体的相对生长速率显著下降,最大光化学量子产量、最大相对电子传递速率和相对电子传递效率呈相同的变化趋势.随着Cu²⁺浓度的升高,龙须菜藻体最大净光合速率和光饱和点显著降低,而光补偿点显著升高,叶绿素a、类胡萝卜素和藻胆蛋白含量则呈先升高后下降的趋势;当Cu²⁺浓度达到500 μg·L^-1时,叶绿素a、类胡萝卜素和藻胆蛋白含量显著下降.说明龙须菜在低浓度Cu²⁺胁迫下具有一定的抵抗能力,而当Cu²⁺浓度≥50 μg·L^-1时,会对藻体生理活动造成显著的抑制作用.     

二氧化氮对樟树幼苗生长及光合作用的影响

采用开顶式人工熏气装置,对1年生樟树幼苗进行了为期2个月不同体积分数NO₂(0.1、0.5和4.0 μl·L^-1)熏气试验,研究其对幼苗生长及光合作用的影响.结果表明:0.5和0.1 μl·L^-1 NO₂处理促进了樟树幼苗生长,而4.0 μl·L^-1 NO₂处理则抑制其生长.各处理樟树幼苗叶片净光合速率(P_n)日变化呈不对称的双峰型曲线,存在光合“午休”现象;在光合日进程中,0.5 μl·L^-1 NO₂处理使叶片P_n提高,最大值达8.542 μmol CO₂·m^-2s^-1,4.0 μl·L^-1NO₂处理的大多数时段使P_n降低,而0.1 μl·L^-1 NO₂处理对P_n的影响则依时段而不同;0.5和4.0 μl·L^-1 NO₂处理提高了叶片气孔导度(G_s)和胞间CO₂浓度(C_i)的最大值和最小值,0.1 μl·L^-1 NO₂处理提高了C_i的最大值和最小值,降低了G_s的最大值和最小值.熏气处理中、后期,0.5μl·L^-1 NO₂处理叶片的日均净光合速率显著高于其他处理.在熏气处理前期,0.5和4.0 μl·L^-1 NO₂处理使叶片最大PSⅡ的光能转换效率(F_v/F_m)显著下降;在熏气处理后期,4.0 μl·L^-1 NO₂处理的叶片F_v/F_m仍显著低于对照.     

钾素水平对网纹甜瓜叶片光合特性及叶绿体亚显微结构的影响

在设施基质栽培条件下,研究了营养液中120、240及360 mg·L^-1 3个钾素水平对网纹甜瓜‘甜甜1号’叶片光合特性及叶绿体亚显微结构的影响.结果表明,营养液中钾素水平过低（120 mg·L^-1）或过高（360 mg·L^-1）均导致网纹甜瓜叶片净光合速率下降,使叶绿体片层结构混乱、变形和片层数减少,但对CO₂补偿点（70 μl·L^-1）、饱和CO₂（600 μl·L^-1）、光补偿点（50 μmol·m^-2·s^-1）无显著影响.适宜的钾素水平能显著提高叶片的饱和光强、羧化效率和表观量子效率,3个指标分别为1 200 μmol·m^-2·s^-1、0.1364和0.0237.在试验条件下,提高温室内基质栽培网纹甜瓜叶片光合效率的最适钾素水平为240 mg·L^-1.     

镉暴露诱导黄颡鱼鳃的组织学损伤、氧化应激和免疫反应

为研究水体镉(Cd)暴露对黄颡鱼(Pelteobagrus fulvidraco)鳃的组织学结构、抗氧化状态及免疫相关基因表达的影响, 将黄颡鱼分别暴露于0(对照组)、50和200 μg/L Cd水体中8周后, 取鳃进行分析。结果显示: 鳃中Cd含量随着水体Cd浓度的升高而上升; 组织学分析发现, Cd暴露组鳃出现了动脉瘤、细胞增生、鳃小片弯曲以及细胞脱落等病理变化。同时, Cd暴露导致鳃中谷胱甘肽-S-转移酶(GST)、谷胱甘肽过氧化物酶(GPx)和抗羟自由基(AHR)的活性及过氧化氢(H₂O₂)的含量升高, 而过氧化氢酶(CAT)的活性及还原型谷胱甘肽(GSH)的含量下降, 但超氧化物歧化酶(SOD)的活性无显著变化。此外, Cd暴露上调了肿瘤坏死因子-α(tnf-α)、主要组织相容性复合体(mhc)、白细胞介素-10(il-10)、转化生长因子-β(tgf-β)和补体因子C3(c3)的表达, 而下调了白细胞介素-1β(il-1β)、白细胞介素-8(il-8)及溶菌酶(lys)的转录水平。研究表明, Cd暴露导致黄颡鱼鳃中Cd富集, 进而诱导鳃的组织学损伤、氧化应激和免疫反应。     

外源甜菜碱对水分胁迫下桃树生理响应的影响

以4年生盆栽“庆丰”桃树为试材,研究了水分胁迫下桃树叶片中甜菜碱含量的变化规律及叶面喷施甜菜碱对水分胁迫下桃树生理响应的影响.结果表明：正常供水情况下,桃树叶片中甜菜碱含量为75.9～80.5 μg·g^-1FM , 随着水分胁迫程度的加深,甜菜碱含量逐渐增加,停水第16 天时达278.9 μg·g^-1FM ;正常供水时桃叶片细胞质膜透性为8.06%～8.61%,水分胁迫下增至28.62%,叶面喷施100和500 mg·L^-1甜菜碱16d后分别为26.25%和21.79%;过氧化氢(H₂O₂)含量由正常情况下的27.2～32.5 μmol·g^-1FM 增至胁迫后的76.4 μmol·g^-1FM,叶面喷施100和500 mg·L^-1甜菜碱后分别为73.2和68.5 μmol·g^-1 FM;水分胁迫下,抗坏血酸过氧化物酶(AsA-POD)活性峰值为0.435 mg·g^-1 FM,甜菜碱处理后峰值达到0.490 mg·g^-1 FM;游离脯氨酸与可溶性糖在干旱胁迫下逐渐累积, 500 mg·L^-1甜菜碱处理分别为2.878 mg·g^-1 FM和37.6 mg·g^-1 FM,均低于单纯胁迫及100 mg·L^-1甜菜碱处理;可溶性蛋白质含量在水分胁迫下呈下降趋势,甜菜碱处理后最小值为4.03 mg·g^-1 FM,较单纯胁迫下的最低值（3.14 mg·g^-1 FM）高20.3%.表明叶面喷施甜菜碱能在一定程度上减轻桃树的受害程度,提高其抗旱性.     

化学诱抗剂诱导黄瓜抗盐性及其机理

在200 mmol·L^-1 NaCl胁迫条件下,采用根际注射结合叶面喷洒的诱导方法探讨了不同浓度水杨酸、油菜素内酯、壳聚糖、亚精胺4种化学诱抗剂对黄瓜幼苗生长及其生理生化特性的影响.结果表明,4种化学诱抗剂在适宜浓度范围内,显著地降低了黄瓜幼苗的盐害指数和死苗率,以油菜素内酯0.01 mg·L^-1降低幅度最大,比对照分别降低了63.0%和75.0%;显著地促进了超氧化物歧化酶、过氧化物酶、过氧化氢酶等保护酶活性,从而显著降低了丙二醛含量和电解质渗出率,干重含水量显著升高;促进了幼苗的形态建成,植株茎粗、展开叶数及壮苗指数显著提高,壮苗指数以壳聚糖150 mg·L^-1最大,比对照提高了30.9%.说明施用适宜浓度的化学诱抗剂可以诱导黄瓜幼苗的抗盐能力,减缓盐害症状.综合作用效果依次为：油菜素内酯0.005～0.05 mg·L^-1、亚精胺150～200 mg·L^-1、壳聚糖100～200 mg·L^-1和水杨酸50～150 mg·L^-1.     

广州海域环境质量评价

根据2003年8月至2004年8月的水质调查数据,运用水质质量单项标准指数法、综合指数WQI法和富营养化评价法,对广州海域环境质量进行评价.结果表明,广州海域主要污染物质为DIN、PO₄^3--P、油类、Cu和Pb,其年平均浓度分别为1.87 mg·L^-1、0.049 mg·L^-1、0.107 mg·L^-1、6.07 μg·L^-1和1.43 μg·L^-1.其中,DIN的污染情况最严重,所有监测站位DIN含量均超过四类海水水质标准,其平面分布呈现从湾内向湾外递减的特征.受珠江径流和陆源排污等的影响,广州海域大部分处于重度污染,且严重富营养化,其单项污染指数、综合污染指数和富营养化指数的平均值分别为2.22、6.80和48.44,表现为从湾内向湾外递减的趋势,高值区均出现在黄埔港至狮子洋海域.     

盐胁迫对长春花幼苗生长和生物碱含量的影响

以NaCl浓度分别为0、50、100、150、200和250 mmol·L^-1的1/2 Hoagland营养液处理长春花幼苗,7 d后测定其鲜质量、干质量、丙二醛(MDA)和叶绿素含量、色氨酸脱羧酶（TDC）和过氧化物酶（POD）活性等生理指标及文多灵、长春质碱、长春新碱和长春碱等生物碱含量.结果表明：NaCl显著地降低长春花幼苗的鲜质量和干质量,提高MDA含量;叶绿素含量在低盐浓度(50 mmol·L^-1)下与对照相比差异不显著,在高于50 mmol·L^-1时随NaCl浓度的增加而逐渐降低;在NaCl处理下,POD活性与对照相比显著上升;TDC活性在50 mmol·L^-1 NaCl处理下活性最高,而后随盐浓度的增加逐渐降低;文多灵、长春质碱、长春新碱和长春碱含量都是在50 mmol·L^-1NaCl处理下最高,分别为4.61、3.56、1.19和2.95 mg·g^-1,并显著高于对照及其他处理.盐胁迫虽然在一定程度上抑制了长春花幼苗生长,但促进了其生物碱的代谢,提高了生物碱含量;50 mmol·L^-1NaCl处理对长春花吲哚生物碱代谢的促进作用最大.     

铜污染对野艾蒿生长发育的胁迫及伤害

通过水培试验,研究了Cu污染对野艾蒿生长发育的胁迫伤害.试验设Cu浓度为2.5、5、10、20和40 mg·L^-1,以植物生长指标及生理指标为测试指标,试验周期14 d.结果表明, 低浓度Cu处理(2.5 mg·L^-1)对野艾蒿生长有促进作用,但随Cu浓度增高(5～40 mg·LL^-1)则产生抑制效应.各项生长指标均与Cu浓度呈极显著负相关,叶绿素含量也产生类似变化.几种光合色素对Cu的敏感性顺序为：叶绿素a＞叶绿素a+b＞叶绿素b＞类胡萝卜素.叶细胞膜渗透性、O₂^-·产生速率和丙二醛(MDA)含量在Cu浓度为2.5 mg·L^-1时较对照略有下降,再随Cu浓度升高而不断上升.POD、SOD和CAT活性随Cu浓度升高先上升,后下降,与根系耐性指数变化一致.在Cu浓度不超过20 mg·L^-1情况下,根系耐性指数＞0.5;Cu浓度为40 mg·L^-1时,根系耐性指数降低为0.36.     

Tissue-specific cadmium accumulation and metallothionein-like protein levels during acclimation process in the Chinese crab Eriocheir sinensis

Aquatic organisms chronically exposed to cadmium can increase their resistance to a subsequent elevated exposure. In order to investigate mechanisms involved in acclimation process in the Chinese crab Eriocheir sinensis, we compared Cd level as well as metallothionein-like protein (MTLP) content in different tissues after direct acute exposure (i.e. 500 microg Cd L(-1) for 3 days), and after acute following chronic (i.e. 10 or 50 microg Cd L(-1) for 30 days) exposure. Cadmium accumulation occurred in the following order: anterior gill>hepatopancreas>posterior gill>carapace>hemolymph>muscle. As high concentrations as 188 microg Cd g(-1) w.w. were reported in anterior gills and seem to reach a saturation level. In these gills, the highest MTLP induction was observed after a direct acute exposure, for which a correlation with Cd content occurred. However, the Cd-binding potential by MTLPs was exceeded for any exposure condition. In hepatopancreas, the highest Cd level was reported for crabs acclimated during 30 days to 50 microg Cd L(-1) before challenging with an acute exposure. Moreover, we showed that MTLPs were induced during the acclimation process. In this organ, MTLPs are theoretically sufficient to bind all Cd. These results suggest that during a chronic exposure to 50 microg Cd L(-1), Chinese crabs acquire the capacity to hold more cadmium in hepatopancreas where it can be sequestrated by MTLPs. On the contrary, MTLP induction seems to be a rapid response to acute exposure in anterior gill, but is not sufficient to sequester all Cd. Other sequestration and/or detoxification mechanisms must take place in anterior gill to cope with high Cd levels.     

Biological monitoring of lead and cadmium in human hair and nail and their correlations with biopsy materials, age and exposure

Hair and fingernails of exposed and unexposed subjects were analyzed for their lead (Pb) and cadmium (Cd) contents by atomic absorption spectrophotometer with graphite furnace and air-acetylene flame. Hair and nail Pb concentrations in occupationally exposed subjects ranged between 1.020-409.726 and 8.130-765.306 microg/g and in environmentally unexposed subjects 0.123-25.160 and 1.076-65.613 microg/g, respectively. Similarly, hair and nail Cd concentrations in occupationally exposed subjects ranged between 0.014-22.086 and 0.214-35.714 microg/g and in environmentally unexposed subjects 0.113-1.627 and 0.028-8.108 microg/g, respectively. A significant correlation was observed between Pb hair and nail concentrations in exposed subjects at P < 0.05, as compared to unexposed subjects and Cd hair and nail in exposed, as well as unexposed subjects. With respect to exposure, levels of Pb in hair and nails were found to be significant in exposed subjects, compared to unexposed ones and levels of Cd were significant only in nails of exposed ones. With respect to age, no significant correlation was found between hair and nail Pb and Cd concentrations in both exposed and unexposed subjects.     

Accumulation, detoxification, and genotoxicity of heavy metals in Indian mustard (Brassica juncea L.)

Plants of Indian mustard (Brassica juncea L.) were exposed to different concentrations (15, 30, 60, 120 microM) of (Cd, Cr, Cu, Pb) for 28 and 56 d for accumulation and detoxification studies. Metal accumulation in roots and shoots were analyzed and it was observed that roots accumulated a significant amount of Cd (1980 microg g(-1) dry weight), Cr (1540 microg g(-1) dry weight), Cu (1995 microg g(-1) dry weight), and Pb (2040 microg g(-1) dry weight) after 56 d of exposure, though in shoot this was 1110, 618, 795, and 409 microg g(-1) dry weight of Cd, Cr, Cu, and Pb, respectively. In order to assess detoxification mechanisms, non-protein thiols (NP-SH), glutathione (GSH) and phytochelatins (PCs) were analyzed in plants. An increase in the quantity of NP-SH (9.55), GSH (8.30), and PCs (1.25) micromol g(-1) FW were found at 15 microM of Cd, however, a gradual decline in quantity was observed from 15 microM of Cd onwards, after 56 d of exposure. For genotoxicity in plants, cytogenetic end-points such as mitotic index (MI), micronucleus formation (MN), mitotic aberrations (MA) and chromosome aberrations (CA) were examined in root meristem cells of B. juncea. Exposure of Cd revealed a significant (P < 0.05) inhibition of MI, induction of MA, CA, and MN in the root tips for 24 h. However, cells examined at 24 h post-exposure showed concentration-wise recovery in all the endpoints. The data revealed that Indian mustard could be used as a potential accumulator of Cd, Cr, Cu, and Pb due to a good tolerance mechanisms provided by combined/concerted action of NP-SH, GSH, and PCs. Also, exposure of Cd can cause genotoxic effects in B. juncea L. through chromosomal mutations, MA, and MN formation.     

Energetics in Atlantic salmon (Salmo salar L.) parr fed elevated dietary cadmium

Atlantic salmon (Salmo salar L.) parr were reared for 4 months on experimental diets supplemented with Cd (0.5, 5, 25, 125, or 250 mg Cd x kg(-1)) to assess the long-term energetic changes based on the digestibility and biochemical deposition of the major dietary nutrients and to evaluate a maximum tolerable dietary toxicant concentration. Growth did not differ significantly (P>0.05) from the control groups. The biochemical composition of the carcass, but not the viscera, was negatively affected by dietary Cd exposure. The significant decreases in protein, lipid, and glycogen concentrations in the carcass (P<0.05, 25 mg x kg(-1) compared to control groups) caused a reduction in calculated whole-body energy content in fish fed 125 mg x kg(-1)compared to control groups. This reduction in calculated whole-body energy content was explained by a concurrent significant disturbance to the gastrointestinal function (measured as reduced digestibility). Only at the highest dietary Cd exposure (250 mg x kg(-1)), increased metabolic costs to cope with Cd toxicity was thought to contribute significantly to the reduction in carcass energy content. The most important factor effecting calculated total energetics was nutrient digestibility. Based on the logarithmic effective median concentration for reduced calculated energy digestibility (dietary Cd concentration corresponding to 50% reduction, EC50), the maximum tolerable dietary Cd concentration is 11 mg x kg(-1) diet.     

Infectivity of Ornithodiplostomum ptychocheilus and Posthodiplostomum minimum (Trematoda: Diplostomidae) cercariae following exposure to cadmium

The effect of cadmium (Cd) exposure on infectivity of cercariae of 2 trematode species (Ornithodiplostomum ptychocheilus and Posthodiplostomum minimum) to their second intermediate fish host was evaluated. Individual fathead minnows (Pimephales promelas) were exposed to cercariae that had been treated with Cd solutions at concentrations of 0, 2, 20, or 200 microg/L for 2 hr. Two weeks later, the numbers of encysted metacercariae in the brain (O. ptychocheilus) and body cavity (P. minimum) of the fish were evaluated. ANOVA analyses indicated a strong negative effect of Cd concentration on cercaria infectivity. The species x Cd concentration interaction was not significant, indicating that the magnitude of Cd-induced reduction in infectivity was similar between O. ptychocheilus and P. minimum. The results show that short-term exposure to Cd, even at low concentrations, interferes with transmission processes that affect the recognition and penetration of cercariae, the migration and survival of metacercariae within the second intermediate host, or both.     

Physiological effects of dietary cadmium acclimation and waterborne cadmium challenge in rainbow trout: respiratory, ionoregulatory, and stress parameters

A suite of respiratory, acid-base, ionoregulatory, hematological, and stress parameters were examined in adult rainbow trout (Oncorhynchus mykiss) after chronic exposure to a sublethal level of dietary Cd (500 mg/kg diet) for 45 days and during a subsequent challenge to waterborne Cd (10 microg/L) for 72 h. Blood sampling via an indwelling arterial catheter revealed that dietary Cd had no major effects on blood gases, acid-base balance, and plasma ions (Ca(2+), Mg(2+), K(+), Na(+), and Cl(-)) in trout. The most notable effects were an increase in hematocrit (49%) and hemoglobin (74%), and a decrease in the plasma total ammonia (43%) and glucose (49%) of the dietary Cd-exposed fish relative to the nonexposed controls. Dietary Cd resulted in a 26-fold increase of plasma Cd level over 45 days (approximately 24 ng/mL). The fish exposed to dietary Cd showed acclimation with increased protection against the effects of waterborne Cd on arterial blood P(aCO2) and pH, plasma ions, and stress indices. After waterborne Cd challenge, nonacclimated fish, but not Cd-acclimated fish, exhibited respiratory acidosis. Plasma Ca(2+) levels declined from the prechallenge level, but the effect was more pronounced in nonacclimated fish (44%) than in Cd-acclimated fish (14%) by 72 h. Plasma K(+) was elevated only in the nonacclimated fish. Similarly, waterborne Cd caused an elevation of all four traditional stress parameters (plasma total ammonia, cortisol, glucose, and lactate) only in the nonacclimated fish. Thus, chronic exposure to dietary Cd protects rainbow trout against physiological stress caused by waterborne Cd and both dietary and waterborne Cd should be considered in determining the extent of Cd toxicity to fish.     

Hyperaccumulation of cadmium by roots, bulbs and shoots of garlic (Allium sativum L.)

The effects of cadmium chloride concentration on root, bulb and shoot growth of garlic (Allium sativum L.), and the uptake and accumulation of Cd2+ by garlic roots, bulbs and shoots were investigated. The range of cadmium chloride (CdCl2 x 2.5H2O) concentrations was 10(-6) - 10(-2) M. Cadmium stimulated root length at lower concentrations (10(-6) - 10(-5) M) significantly (P < 0.005) during the entire treatment period. The seedlings exposed to 10(-3) - 10(-2) M Cd exhibited substantial growth reduction (P < 0.005), but did not develop chlorosis. Garlic has considerable ability to remove Cd from solutions and accumulate it. The Cd content in roots of garlic increased with increasing solution concentration of Cd2+. The roots in plants exposed to 10(-2) M Cd accumulated a large amount of Cd. approximately 1,826 times the control. The Cd contents in roots of plants treated with 10(-3), 10(-4), 10(-5) and 10(-6) M Cd were approximately 114, 59, 24 and 4 times the control, respectively. However, the plants transported only a small amount of Cd to their bulbs and shoots and concentrations in these tissues were low.     

Urinary selenium excretion in selenite-loaded sheep and subsequent Se dynamics in blood constituents

Renal selenium excretion in sheep was measured during intravenous infusion of sodium selenite, and the post-infusion dynamics of Se levels in whole blood, plasma and red blood cells (RBC) were investigated for the next 5 days. The plasma Se level increased almost twenty fold with the infusion of Na2SeO3 (from 0.39 +/- 0.02 to 7.83 +/- 0.33 micromol x L(-1), P < 0.001) compared with the baseline value. The selenium concentration in urine (0.07 +/- 0.02 vs. 18.53 +/- 2.56 micromol x L(-1), P < 0.001), the amount of Se excreted (0.14 +/- 0.07 vs. 21.40 +/- 2.31 nmol x min(-1), P < 0.001) and the renal clearance of Se (0.1 9 +/- 0.03 vs. 3.01 +/- 0.34 mL x min(-1), P < 0.001) were found to be highly significantly elevated during selenite loading. The clearance measurements showed no changes in the urinary flow rate or in the glomerular filtration rate. During and at the end of infusion the highest Se level was attained in plasma, followed by whole blood and RBC. The plasma Se level fell rapidly within 10 min after the end of infusion, but the concentration of Se in RBC was stable up to the fourth hour, when it started to decrease too. On day 5 the Se concentrations in plasma, RBC and whole blood were found to be only slightly but still significantly higher than before the selenite infusion. The large disproportion between the infusion rate of Se (8.76 microg x min(-1)) and its renal excretion rate (1.69 microg x min(-1)) found in clearance measurements suggests low glomerular filtration of infused selenium, which might primarily be caused by the binding of selenite metabolites to blood constituents. The presented results confirm the low bioavailability to ruminants of Se from sodium selenite.     

镉胁迫对不同甘蓝基因型光合特性和养分吸收的影响

以2个耐镉(Cd)性不同的甘蓝品种为材料,研究了不同Cd浓度(0、20、50、100μmol.L-1)对甘蓝植株生长、叶片光合特性和养分吸收的影响.结果表明:Cd敏感品种在低浓度Cd(20μmol.L-1)处理下生长受到明显抑制,叶片净光合速率(Pn)、气孔导度(Gs)、PSⅡ光化学效率(Fv/Fm)、PSⅡ光合电子传递量子效率(ΦPSⅡ)及地上部、根系干质量显著降低;Cd耐性品种在高浓度Cd(50和100μmol.L-1)处理下生长和光合特性受到显著影响;Cd胁迫降低了甘蓝叶片叶绿素a和b含量,尤其对叶绿素a的影响较大,进而抑制了叶片光合能力.Cd胁迫显著降低了植株对Mn的吸收,抑制了Mg和Fe从根部向地上部的转运,且Cd敏感品种受抑制幅度更大;Cd胁迫促进了Cd耐性品种对P和S的吸收,而Cd敏感品种相反.因此,Cd胁迫下甘蓝敏感品种叶片Mn、Fe、Mg、S和P含量的降低是影响其叶片光合作用,进而抑制植株生长的重要生理原因.