NP Treatment Research Articles

Combined effects of nutrients and small-scale turbulence in a microcosm experiment. I. Dynamics and size distribution of osmotrophic plankton

The response of phytoplankton and bacteria dynamics to turbulence and nutrient avail- ability interactions was studied in natural coastal waters enclosed in 15 l microcosms. The effect of turbulence was examined under 3 different nutrient-induced conditions: nitrogen surplus (N, with initial addition of an excess of nitrogen, N:P ratio = 160), nitrogen:phosphorus ratio balanced (NP, with initial addition of nitrogen and phosphorus as Redfield ratio, N:P ratio = 16) and control (C, no nutrient addition). Turbulence (e = 0.055 cm 2 s -3 ) was generated by vertically oscillating grids. The experiment lasted for 8 d and samples were generally taken daily for nutrient and plankton mea- surements. Turbulence increased the relative importance of phytoplankton to bacteria when nutri- ents were added, while in the control the effect of turbulence was negligible. Turbulence also influ- enced the species' composition and the size distribution of the phytoplankton community. The relative contribution of diatoms to total phytoplankton biomass and the average cell size were higher under turbulence, particularly in N and NP treatments. The results of these experiments indicate the importance of considering the hydrodynamic conditions in studies addressing competition for nutri- ents among different osmotrophic organisms in plankton communities.

Effect of Estradiol and Nonylphenol on mRNA Expression of Estrogen Receptors α and β, and Cytochrome P450 Aromatase in the Gonad of Chicken Embryos

Effects of estradiol-17β (E2) and p-nonylphenol (NP) on mRNA expression of estrogen receptor α (ERα), estrogen receptor β (ERβ) and cytochrome P450 aromatase (P450arom) were examined in the early stage of chicken embryonic gonads. Fertilized eggs were treated with either E2 (1.0 mg/egg) or NP (0.01, 0.1 mg/egg) immediately before incubation (day 0 of incubation) and were incubated at 37.5°C. In the control group the eggs were treated with the vehicle (10% propanediol, PD, 50μl). On day 10 of incubation the gonad was collected and mRNA expression was determined for semi-quantitative assay by the reverse transcription-polymerase chain reaction (RT-PCR). In the control group, ERα and P450arom mRNA showed higher expression in females than in males while ERβ mRNA showed no sexual difference. In the E2 treated group, the expression of ERα and P450arom mRNA markedly increased in males (about 4- and 16-fold, respectively). NP increased mRNA expression of ERα and P450arom (about 2-fold each) in males. ERβ mRNA expression did not apparently change after the E2 or NP treatment in both sexes. These results suggest that NP induces some female-specific genes in the male gonads during the critical period of sex determination in chicken embryos.

Potassium release rates from ustisols and their application

Second-order equations were used to characterize the potassium release rate for 20 low-hilly ustisols derived from Quaternary red clay in Zhejiang province, China. This was done under the condition of electric field strength of 44.4 and 88.8 V cm−1. The values of the initial K release rate (v0) ranged from 1.17 to 21.23 and from 1.93 to 61.58, with an average of 5.36 and 9.54 mg kg−1 min−1 under the electric field strength of 44.4 and 88.8 V cm−1, respectively. Six indices, including the relative grain yield, relative total dry matter yield and K uptake in NP treatments of 20 corn field experiments and available K, HNO3 soluble K and slowly available K of soils were used to assess the practical applicability of K release rates. The correlation analysis showed that v0 was very significantly correlated (P=0.01) with the above six indices, and their correlation coefficients were 0.6275**, 0.5645**, 0.6624**, 0.7277**, 0.7843** and 0.6299**, respectively, under the electric strength of 44.4 V cm−1. The v0 was related to relative total dry matter yield (P = 0.05, r = 0.5445*) and very significantly correlated to the other five indices (relative grain yield, K uptake in NP treatment, available K, HNO3 soluble K and slowly available K), with the correlation coefficients of 0.6064**, 0.7216**, 0.7523**, 0.8202** and 0.6686**, respectively, under the electric strength of 88.8 V cm−1. From the results, we conclude that v0 can be used to estimate the supplying power of soil K to annual crops such as corn, and to characterize soil K fertility.

Assimilating efficiency of soil nutrition ofPhalaris arundinacea L.

Phalaris arundinacea L. is fine perennial herbage of Gramineae. Eight treatments including N, P, K, NP, NK, NPK, PK and controls were done for studying its absorbing efficiency of soil nutrition. At tillering stage, the coefficient of absorbing and utilizing of N. P, and K from soil and fertilizer were analyzed according to M.K. Kaeomobk’s formula and the contents of crude protein and fat were also measured. The yields of fresh crop, hay and seed were measured at ripening stage. For N absorbing coefficient ofPh. arundinacea from soil (Kn%), the composition PK treatment is best (12.36%) and K treatment is worse, while for N absorbing coefficient from fertilizer (Ky%), all the treatments are higher than control but the composition NPK treatment presented the highest (14.78%). For the absorbing coefficient of P from soil (Kn%), composition NK treatment is highest (19.30%), but K treatment was lower than control, while for that of P from fertilizer (Ky%), all the treatment were higher than control but the composition NP treatment showed the highest (19.52%). As to K absorbing coefficient from soil (Kn^), NP treatment is the best (19.2%) and single P treatment is worst, while for that (Ky%) of K from fertilizer the composition NPK treatment was best (28.44%). As concerns treatments for the outputs of fresh and dry crop, the composition NP treatment was best and all the treatment were higher than control. The composition NK treatment produced highest yield of seed and highest content of crude protein as compared to other treatments For content of crude fat, the compositions NK and N treatments are best. The experiment indicates that application of fertlizer at proper proportions could increase the yield ofPh. Arundinacea and raise the utilizing efficiency of nourishment element from soil and fertilizer.

Effect of nutrient management on rice(Oryza in sativa) rainfed lowland of southeast ~ a d h Pradesh ~ a

In a 3-year field trial, efficiency of different fertilizers in rainfed lowlands was evaluated at the Zonal Agricultural Research Station, Jagdalpur (M.P.). - Application of N fertilizer and manures significantly increased the yield and N, P, K uptake by rice (Oryza sativa L.) over control and PK only. The higher grain and straw yields of rice were obtained in the treatment receiving YZ FYM + NP (2.58 and 4.90 t/ha), followed by NPK + FYM (2.49 and 5.71 t/ha), CR-N (35) PK (2.14 and 4.31 t/ha) and CR-NPK+Zn (2.13 and 4.68 t/ha). Agronomic efficiency was also higher in 1/2 FYM + NP treatment, followed by CR-N (3s) and CR-NPK + Zn. X Nut~ient water interaction helped buffer the adverse effect of moisture deficit for h sustaining rice yield during 1997. The application of manure alone or in combination with chemical fertilizers sustained/improved the soil-fertility status of the soil.

Soil physico-chemical properties as affected by integrated use of blended fertilizer, cattle manure, vermicompost and mineral nitrogen and phosphorus in potato (Solanum tubersoum) in acidic soil of south-western Ethiopia

A field experiment was conducted in Belg (February to May) and Meher (June to October) seasons of 2020 at Abelo kebele in Masha district of Ehiopia, to determine the effects of blended mineral NPSB fertilizer, cattle ma- nure (CM), vermicompost (VC) and mineral NP on soil physico-chemical properties with a view to generate new data and extend community service to farmers. The fertilizer treatments consisted of 7.5 t CM/ha combined with 75% and 50% of recommended dose of NP fertilizers (RDF), 7.5 t VC/ha combined with 75, 50 and 25% of NP, 5 t VC/ha combined with 75% NP, 100 kg NPSB/ha + 61.5 kg P/ha + 146 kg N/ha, 150 kg NPSB + 53.7 kg P/ha + 138 kg N/ha, 200 kg NPSB + 46 kg P/ha + 128 kg N /ha, 100% of NP (165 kg N/ha+60 kg P/ha) and no-fertilizer treat- ment (control), making a total of 11 treatments. The experiment was laid out in a randomized complete-block de- sign with 3 replications. Results indicated that the application of 75% of NP (124 kg/ha + 45 kg P/ha) combined with 7.5 t/ha VC significantly increased the soil pH (6 and 7.29%), organic carbon (62.3 and 119%), total N (85 and 135%), available P (64.72 and 62.66%), cation-exchange capacity (CEC) (16.5 and 31.92%), exchangeable Ca+2 (16.3 and 18.25%), exchangeable Mg+2 (19.8 and 141.42%), exchangeable K+ (7.14 and 18.33%) and reduced the bulk density (7.87 and 9.52%), exchangeable acidity (368 and 455%), exchangeable aluminum (377 and 249%) in Belg and Meher seasons, respectively. Thus, the use of 7.5 t VC/ha combined with 75% of mineral nitrogen (124 kg N/ha + 45 kg P/ha) could significantly enhance the soil physico-chemical properties of acidic soil over sole ap- plication of either 200% mineral NPSB or 150% mineral NPSB or 100% NP or control treatment.

Tratamento da hipertensão arterial - respostas de médicos brasileiros a um inquérito

The third Brazilian Consensus of Hypertension recomends the usage of pharmacological (PT) and non-pharmacological treatment (NPT). In Brazil, we don't know how if this recommedation has been followet by doctors. a) to characterize NPT regarding prescription and acceptability by hypertensive patients; b) characterize PT concerning the criterion used for choosing medication and medication prescribed; and c) identify doctors' opinions about patients' degree of acceptability to PT and NPT. 37904 questionnaires with reply-paid envelopes were sent to Brazilian doctors and 2519 of those were replied (57% from the Southeast region, 41% were cardiologists, and 26% clinicians). 1- 62% of doctors recommend NPT to 25% of their patients. 2 - The most recommended NP treatments are: hyposodic diet (55%), weight reduction (29%) and physical exercises (8%), considering that doctors believe that 50% of their patients follow a hyposodic diet, 20% do physical exercises and 19% lose weight. 3 - Only one medication is prescribed at the beginning of a PT (88%) and when blood pressure isn't under control, 55% of the doctors associate other medications with it whereas 33% of them increase the dose. 4 - The most prescribed medications are: diuretics (53%) and ECA inhibitors (24%). 5 - The main criteria for choosing medication are: personal experience (32%) and characteristics of patients (31%). 6 - Doctors (60%) believe that acceptability to PT is better. The recommendations of the Third Brazilian Consensus of Hypertension have been followed partially concerning NPT and as expected regarding PT.

In vivo modulation of nonylphenol-induced zonagenesis and vitellogenesis by the antiestrogen, 3,3′4,4′-tetrachlorobiphenyl (PCB-77) in juvenile fish

Zonagenesis and vitellogenesis (eggshell zona radiata protein ( Zrp) and vitellogenin (Vtg) production, respectively), are two estrogen-regulated processes in oviparous vertebrates that are crucial for oocyte maturation. Treatment of juvenile Atlantic salmon ( Salmo salar) with nonylphenol (NP; 25 mg kg −1) alone or in combination with 3,3′,4,4′-tetrachlorobiphenyl (TCB; 0.1 mg kg −1) resulted in pronounced elevations of plasma eggshell Zrp and Vtg and their respective liver mRNA levels in two separate experiments. TCB treatment alone caused the elevation of CYP1A mRNA, protein and enzyme levels (7-ethoxyresorufin O-deethylase (EROD)). In experiment 3, which also included the time factor, exposure of juvenile salmon to 10 and 25 mg NP per kg in combination with TCB generally resulted in reduced plasma Zrp and Vtg levels, compared with NP treatments alone. In a fourth experiment, juvenile salmon were exposed to different doses of TCB either 2 days before or 2 days after a single dose (25 mg kg −1) of NP. Samples were always collected 5 days after the NP exposure and analyzed for mRNA and protein levels. Generally, TCB doses given 2 days after NP exposure resulted in the elevation of Vtg and Zrp protein and mRNA levels. Vtg and Zrp mRNA levels were also elevated in the groups treated with 0.1 mg TCB 2 days before NP exposure. In all experiments, TCB injection resulted in the induction of liver CYP1A mRNA, CYP1A protein and EROD activity, but no Zrp or Vtg protein/mRNA inductions were observed when given alone. The present study documents for the first time the apparent stimulation of xenoestrogen-induced responses by an antiestrogenic CYP1A-inducer, in fish or any other lower vertebrate. However, the stimulatory or inhibitory effect of TCB on NP-induced responses appear to be dependent on the ratio of NP and TCB doses, and temporal sequence of exposure. Fish hepatic zonagenesis and vitellogenesis continue to provide interesting models for further studies on the mechanisms and possible interactions between endocrine disruptors and CYP1A-inducers, their antiestrogenic and/or estrogen potentiating effects.

Reversal of density dependence of juvenile Littorina littorea (Gastropoda) growth in response to periphyton nutrient status

Experimental periphyton communities were grown in aquaria receiving media of differently enriched seawater (fully enriched, without Si enrichment, without N and P enrichment) and supplied differently with medium (batch and weekly replacement). Periphyton was subject to grazing by 1–6 individuals of juvenile Littorina littorea. Periphyton biomass was higher in the replacement aquaria than in the batch aquaria and higher in the full and the –Si medium than in the –NP medium. The N:C ratio of the periphyton increased with Littorina number in the batch aquaria and was unaffected by Littorina number in the replacement aquaria. Diatoms were most dominant in the –NP treatments and rarest in the –Si treatments. Chlorophytes were dominant in the –Si and the fully enriched treatments, but also Cyanobacteria contributed significantly to periphyton biomass in those treatments under nutrient replacement. Somatic growth of Littorina was negatively correlated to Littorina density in the replacement aquaria and positively density dependent in the batch aquaria. The latter is explained by improved food quality under stronger grazing pressure.

The uterotrophic activity of nonylphenol in the rat is not mediated by aromatase enzyme induction

p-Nonylphenol (NP) is weakly estrogenic to rodents and to some species of fish. All evidence to date has indicated that the estrogenic effects of NP are due to the interaction of NP with the estrogen receptor. Recent findings of increased plasma estradiol in fish exposed to NP have, however, led to the proposal of an alternative mechanism for NP-induced estrogenicity in this species, possibly via induction of aromatase enzymes. In the present studies, this hypothesis was investigated in rats using the aromatase inhibitor anastrozole. The results indicated that the uterotrophic action of NP, as with estradiol used as a positive control, is mediated directly by its interaction with uterine ER, rather than an indirect effect via aromatase enzyme induction. Circulating levels of estradiol were unchanged after NP treatment and the aromatase inhibitor anastrozole failed to inhibit NP-induced uterine growth. These results are consistent with previous published data on NP in rodents.

The Use of Living Mulches for Weed Management in Hot Pepper and Okra

ABSTRACT The study evaluated white clover (Trifolium rapens), red clover (T. pratencis), perennial ryegrass (Lolium pratense) and canola (Brassica napus) as living mulches for weed management in hot pepper (Capsicum annum) and okra (Abelmoschus esculentus). Perennial rye-grass and white clover provided the best weed control. Weed control was similar when living mulches were newly planted in the spring (NP) or in the previous year and overwintered (OW). In the NP treatment, weeds were suppressed similarly both in the tilled crop rows and within the mulch. Yields of okra and hot pepper were greatest in the conventional tillage (CT). Mowing of living mulches improved hot pepper yields in red clover but not okra yields.

Maternal and offspring toxicity but few sexually dimorphic behavioral alterations result from nonylphenol exposure

Nonylphenol ethoxylates are used in the production of surfactants and are found in numerous manufactured substances. para-Nonylphenol (NP) is a suspected endocrine disruptor, exhibiting estrogen-like activity and might cause alterations with developmental exposure. To evaluate such effects, pregnant Sprague–Dawley rats consumed diets containing 0 ( n = 11), 25 ( n = 10), 500 ( n = 10), or 2,000 ( n = 9) ppm NP beginning on gestational day (GD) 7. At postnatal day (PND) 21, offspring continued on the same maternal diets until PND 77 and were evaluated for behavioral alterations (open-field activity at PNDs 22–24, 43–45, 64–66, play behavior at PND 35, running wheel activity at PND 63–77, flavored solution intake at PND 69–75). During pregnancy and lactation, dams in the 25-, 500-, and 2,000-ppm groups consumed 9 to 25% less food, which was associated with a 17% less weight gain during GDs 1 to 21 in dams of the 2,000-ppm group, although this effect was not statistically significant. Gestation duration, birth weight, sex ratio of live pups, and number of live or dead pups per litter did not differ between treatment groups. Offspring body weight and food consumption were decreased in the 2,000-ppm group beginning at PND 28; however, an effect of feed aversion could not be eliminated. Behavioral assessments of offspring indicated no consistent NP-related effects in open-field activity at PNDs 22–24, 43–45, and 65–67 nor in running wheel activity at PNDs 63–75. Play behavior at PND 35 and intake of a 0.3% saccharin-flavored solution at PNDs 69–71 did not differ with respect to treatment groups. However, intake of a 3% sodium-flavored solution at PNDs 73–75 was significantly increased in offspring of the 2,000-ppm group and intake of regular water during this same time was also significantly increased. These results indicate that developmental NP treatment results in maternal and offspring toxicity as evidenced by decreased food intake and weight gain. However, behavioral alterations were evident only in increased intake of a sodium solution.

Effects of xenoestrogen treatment on zona radiata protein and vitellogenin expression in Atlantic salmon ( Salmo salar)

Zonagenesis ( zona radiata protein synthesis) and vitellogenesis (yolk protein synthesis) are two reproductive responses that are integral aspects of fish oogenesis. This study examines the responses of eggshell zona radiata proteins ( Zrp) and vitellogenin (Vtg) to five environmental pollutants; 4-nonylphenol (NP) and o, p′-DDT [both at 25 mg/kg], lindane (γ-HCH) [10 mg/kg], a technical PCB mixture (Aroclor 1254; A1254) and bisphenol A (BPA) [both at 5 mg/kg] in juvenile Atlantic salmon ( Salmo salar). Fish were given intraperitoneal injections of o, p′-DDT, γ-HCH, A1254 or BPA; singly, in combination with NP, and as a cocktail of all five chemicals, and later compared to NP-treated and untreated fish. In a separate experiment, fish were exposed to BPA in a dose-response manner (1, 5, 25 and 125 mg/kg fish). Based on previous studies, blood and liver samples were collected 2 weeks after injection. Zrp and Vtg levels were analyzed in plasma using immunoblotting and enzyme-linked immunosorbent assay. Liver cytochrome P4501A was analyzed by 7-ethoxyresorufin O-deethylase (EROD) activity. NP caused pronounced elevations in plasma Zrp and Vtg levels. In comparison, when NP was given in combination with γ-HCH, Vtg levels was significantly reduced, compared to NP treatment alone. Using o, p′-DDT, A1254 and BPA, significant elevations of plasma Zrp and Vtg were seen when chemicals were given in combination with NP, but not when administered by themselves. An apparent dose-response induction of Vtg and Zrp levels were observed in BPA treated juvenile salmon. In immunoblots, one component of molecular weight approximating the Zrp-β was detected when either o, p′-DDT, γ-HCH, A1254 or BPA were given singly. A1254 significantly induced hepatic EROD activity when administered alone. However, when given as a mixture with all the other xenobiotics, reduction of EROD activity was observed. The data suggest a pattern of xenobiotics action which may complicate assessment of their reproductive effects. Zrp (the β monomer) was more responsive to the xenoestrogens than Vtg, and provides a sensitive means of detecting exposure to environmental estrogens.

Effects of nitrogen and phosphorus fertilization in a lowland evergreen rainforest.

A nutrient addition experiment was set up in August 1993 in a species-rich primary lowland dipterocarp forest in Barito Ulu, Central Kalimantan, Indonesia. The following treatments were applied: control, +N, +P and +NP. There were five blocks of four 50 m x 50 m plots with a separate treatment for each plot. Fine litterfall was measured on all the plots from 1 May 1994 for 12 months. Litterfall mass and phosphorus concentrations were significantly higher in all the fertilizer treatments compared with the controls. All trees (> or = 10 cm dbh) were measured in August 1993 and in August 1998, and there was no significant girth increment response to fertilization in dipterocarps or non-dipterocarps. Dipterocarps of the red meranti group showed a doubling of girth increment in the +NP treatment, however, the difference from the control fell short of significance.

Effects of biomass removal in thinnings and compensatory fertilization on exchangeable base cation pools in acid forest soils

The effects of whole-tree harvesting and fertilization at first thinning on the exchangeable pools of base cations in the soil were examined on four sites five years after thinning. One site with Norway spruce ( Picea abies (L.) Karst.) is located in southwestern Sweden and three other sites with Scots pine ( Pinus sylvestris L.) are located in southeastern, south-central and northern Sweden. On all sites, the stands were thinned, and the following treatments were applied in a randomized block design ( n = 3): (i) stem-only harvest, logging residues left on site; (ii) whole-tree harvesting; (iii) whole-tree harvesting combined with compensatory fertilization (N–P–K were applied one year after thinning in the form of inorganic fertilizers, and the amounts were equal to the nutrient content of the harvested logging residues); (iv) stem-only harvesting in combination with N (pine sites) or NP (spruce site) fertilization (ammonium nitrate, 150 kg N ha −1, superphosphate, 30 kg P ha −1) and (v) whole-tree harvesting and nitrogen fertilization as in treatment (iv). There were no general treatment effects revealed from analysis across all sites. Effects of harvesting intensity were detected on two sites, indicating reduced pools of exchangeable K, Mg and Ca after whole-tree harvesting. The reductions were less pronounced than the effects observed in other studies from experiments with whole-tree harvesting at clear-felling of mature forests. Effects of application of nitrogen alone were more frequently observed than effects of harvesting of logging residues. In most cases, base cation pools were lower after N treatment than after other treatments, and this effect was probably due to exchange and translocation phenomena. However, Ca pools had increased after NP treatment on the spruce site due to high content of Ca in P fertilizer. No effect of compensatory fertilization with N–P–K was detected. A comparison between exchangeable nutrient pools before thinning and five years after indicated that K was generally lost from the soil profile.

EFFECTS OF 4-n-NONYLPHENOL ON LIFE-HISTORY TRAITS AND POPULATION DYNAMICS OF A POLYCHAETE

A Life-Table-Response Experiment lasting 78 d was performed to investigate the toxic effects of sediment-associated 4-n-nonylphenol (NP) on growth, reproduction, and survivorship of isolated hermaphrodites of the infaunal polychaete Capitella sp. I. Demographic effects were evaluated using both a fully age-classified and a simple two-stage model to estimate population growth rates (λ). Decomposition analysis was performed to explore the contributions of each of the affected life-history traits to the effects observed on λ. Elasticity analysis was applied to examine the relative sensitivity of λ to changes in each of the different life-history traits under different exposure levels. In the lowest NP treatment (14 μg NP/g dry mass of sediment) significant stimulatory effects were observed for both asymptotic body volume and average brood size, but these did not result in a significant effect on λ. Negative effects on brood size, volume-specific fecundity, time to first reproduction, and individual growth ra...

Corn Production as Affected by Time and Rate of Manure Application and Nitrapyrin

Maximum manure N use efficiency by corn (Zea mays L.) requires that N mineralization and subsequent plant availability coincide with N uptake demand. Information regarding the effects of time of manure application and use of a nitrification inhibitor on manure mineralization and corn yield is needed for producers to make sound manure management decisions. Studies were conducted at seven southern Minnesota sites over 3 yr to determine the effects of three manure application times (mid-September, mid-October, and late April), two manure rates, and a nitrification inhibitor, (nitrapyrin [NP] 1.0 Ib a.i./acre), on corn yield and soil nitrate N concentration (0 to 12 in.) at the V4 growth stage. Application rates ranged from 3000 to 4000 gal/acre for the low rate and from 6000 to 8000 gal/acre for the high rate. For the four sites receiving liquid dairy (Bos taurus) manure, soil nitrate N was greatest when manure was applied in April and lowest when applied the previous September. The addition of NP increased soil nitrate N at three sites but affected grain yields at only one site when averaged across time and rate of manure application. Grain yields for the April, October, and September applications averaged 146, 142, and 139 bu/acre, respectively, across manure rates and NP treatments, with April exceeding the September application time (P < 0.10). When liquid swine (Sus scrofa domesticus) manure was used, the effects of application time and NP on soil nitrate N concentration and grain yield depended on climatic conditions. At one site where 8.5 in, of rain fell in a 5-wk period in the spring, NP significantly increased both soil nitrate N concentration and grain yield for the October application but had no effect with the April application. Similar effects of NP on soil nitrate N were found at the other sites, but grain yields were not increased. Results from the seven site-yr support about a 5% yield increase with April application compared with fall applications. However, it is unlikely that many farmers will consider this an economic advantage because of logistical challenges often faced with spring applications of manure in the Northern Corn Belt.

Lethality and bioaccumulation of 4‐nonylphenol in bluegill sunfish in littoral enclosures

AbstractToxicity and bioaccumulation in bluegill sunfish (Lepomis macrochirus) of 4‐nonylphenol (NP), a common precursor and degradation intermediate of certain nonionic surfactants, were evaluated in a set of 18 aquatic mesocosms (littoral enclosures) in northeastern Minnesota. Nonylphenol was applied to enclosures every 48 h over a 20‐d period (11 applications) at rates of 3, 30, 100, and 300 μg/L. Additional enclosures served as untreated controls. Maximum NP levels in the integrated water column 2 h after each application averaged 5 ± 4, 23 ± 11, 76 ± 21, and 243 ± 41 μg/L over the 11 applications at the 3‐, 30‐, 100‐, and 300‐μg/L treatments, respectively. Sixty‐one percent of the NP dissipated from the water column within ˜39 h of each application. Estimated survival of stocked juvenile bluegills was significantly reduced at the 300‐μg/L NP treatment. No significant effects were noted at the other NP treatments; however, the 100‐μg/L enclosure with the highest mean NP concentration (93 ± 39 μg/L) within that treatment had four to nine times more dead bluegills and four to six times fewer bluegills captured at the end of the season than the other two 100‐μg/L enclosures (64 ± 23 and 71 ± 32 μg/L) and the controls, suggesting increased mortality in this enclosure. Nonylphenol tissue concentrations in juvenile bluegills collected from enclosures treated with 3 and 30 μg/L NP ranged from 0.01 to 2.94 μg/g wet weight and showed a significant positive relationship with the average measured NP concentration in the water. The mean wet weight nonequilibrium NP bioaccumulation factor was 87 ± 124. There was no relationship between fish lipid content and NP tissue concentration.

Effects of repeated exposure to 4-nonylphenol on the zooplankton community in littoral enclosures

The effects of 4-nonylphenol (NP) on freshwater zooplankton were evaluated in 18 littoral enclosure mesocosms in northeastern Minnesota. The 18 enclosures were allocated to three blocks of six units with each block including two untreated control enclosures and one enclosure for each of four NP treatments (3, 30, 100, and 300 μg/L). Treated enclosures received 11 applications of NP over a 20-d period between July 8 and 28, 1993. Maximum NP concentrations measured in the water column 2 h after each application averaged (±SD) 5 ± 4, 23 ± 11, 76 ± 21, and 243 ± 41 μg/L over the 11 applications. Nonylphenol dissipated rapidly from the water column but was more persistent in sediments and in/on macrophytes. All cladoceran and copepod taxa were significantly reduced in abundance at 243 ± 41 μg/L; some sensitive taxa were also affected at 76 ± 21 and 23 ± 11 μg/L. While many rotifer taxa were unaffected at any of the test concentrations, several were affected at ≥76 ± 21 μg/L. Ostracods were only affected at 243 ± 41 μg/L. No zooplankton taxon was affected at 5 ± 4 μg/L. The period of maximum impact usually occurred within 1 to 7 d of the last NP application, and recovery to control abundance levels generally occurred within 7 to 28 d of the last NP application. Two sensitive taxa, Acroperus and Calanoida, did not recover at ≥76 ± 21 μg/L by the end of the study. The maximum acceptable toxicant concentration for protection of all zooplankton taxa was estimated at ˜10 μg/L, although overall community diversity was unaffected at 23 ± 11. The water was the most probable route of NP exposure, but the greater persistence of NP residues in/on macropyhtes may have contributed to the lack of recovery of some macrophyte-associated taxa.

Plasma levels of vitellogenin and eggshell zona radiata proteins in 4-nonylphenol and o,p′-DDT treated juvenile Atlantic salmon ( Salmo salar)

Induction of vitellogenin (Vtg) in males and juveniles of oviparous vertebrates has been used as a biomarker for xenoestrogens. Recently, we have demonstrated that synthesis of eggshell zona radiata proteins (Zrp) or zonagenesis is an integral aspect of fish oogenesis (Oppen-Berntsen et al. (1994) Journal of Experimental Zoology 268, 59–70), and that Zrp synthesis is a sensitive biomarker for nonylphenol (Arukwe et al. (1997) Environmental Health Perspective 105, 418–422). This study compares the responses of Vtg and Zrp in plasma of juvenile Atlantic salmon ( Salmo salar) treated with 4-nonylphenol (NP) and o,p′-DDT (both at 25 mg kg −1, singly and in combination). Validated ELISA and immunoblot analysis show that Vtg and Zrp respond significantly stronger to NP treatment alone and in combination with o,p′-DDT compared to control and o,p′-DDT treatment alone. However, a slight reduction in NP-induced Zrp levels was indicated when NP was injected in combination with o,p′-DDT.