N-Acetyl-L-cysteine prevents exercise-induced intestinal lymphocyte apoptosis by maintaining intracellular glutathione levels and reducing mitochondrial membrane depolarization

Intense exercise leads to post-exercise lymphocytopenia and immunosuppression, possibly by triggering lymphocyte apoptosis. To test the role of oxidative stress on exercise-induced lymphocyte apoptosis, we administered the antioxidant N-acetyl--cysteine (NAC) and measured apoptosis in intestinal lymphocytes (IL) from exhaustively exercised animals. Eighty-seven female C57BL/6 mice were randomly assigned to receive NAC (1 g/kg) or saline 30 min prior to treadmill exercise for 90 min at 2degrees slope (30 min at 22 m min(-1), 30 min at 25 m min(-1), and 30 min at 28 m min(-1)) and sacrificed immediately (Imm) or 24 hours (24 h) after cessation of exercise. Control mice (nonexercised) were exposed to treadmill noise and vibration without running. Exercise increased IL phosphatidylserine externalization (p<0.001), mitochondrial membrane depolarization (p<0.05), and decreased intracellular glutathione concentrations (p<0.05) immediately following exercise in saline relative to nonexercised mice. At 24 h post-exercise, saline injected mice had fewer total (p<0.001) and CD3+ (p<0.005) IL compared to nonexercised animals. NAC injection in mice maintained intracellular glutathione levels, prevented phosphatidylserine externalization, mitochondrial membrane depolarization, and loss of IL immediately and 24 h after exercise. These data suggest that lymphocyte apoptosis precedes post-exercise lymphocytopenia and may be due to oxidative stress.     

Post-illumination stimulation of respiration rate in the coral Porites porites

The respiration rate of the Caribbean reef coral Porites porites was shown to increase by a mean of 39% above the pre-illumination respiration rate when exposed for 3 h to light equivalent to that at 10 m depth on the reef. When exposed to a subsaturating irradiance of 140 E m^-2 s^-1, the respiration rate increased successively in a curvilinear form to 58% greater than the preillumination respiration rate after 80 min. It is suggested that this increase may be analogous to the elevation in respiration rate observed in cnidarians and other animals after feeding on particulate food and may represent energy expenditure in growth. If this elevated respiration rate is maintained over the whole of the daytime period, the current methodologies used for determining carbon and energy budgets in symbiotic cnidarians result in an underestimation of the 24 h energy expenditure.     

The effect of short term thermal stress on the heart and respiration rates of conscious and anaesthetized chickens

Heart and respiration rates were measured in eight 6-week-old, White Rock chicks at different ambient temperatures: 24--26 degrees C (neutral), 6.5--8.5 degrees C (low) and 3,95--43.5 degrees C (high). The animals were exposed to these temperatures for 10 min. In both groups the low ambient temperature did not influence the respiration rate, whereas the high temperature caused a significant increase of the respiration rates both in the conscious and anaesthetized birds. In both groups no significant changes in the heart rate at different temperatures were found. Statistically significant differences in the heart and respiration rates between the conscious and anaesthetized chickens were noted only at the low environmental temperature.     

黄土和风沙土藓结皮土壤呼吸对模拟降雨的响应

生物结皮土壤呼吸是干旱和半干旱生态系统碳循环的重要组成部分,但目前其对降雨的响应规律尚不明确。针对黄土高原黄土和风沙土上发育的藓结皮,分别进行2、4、6、10、20、30、40 mm的模拟降雨,并使用便携式土壤碳通量分析仪测定雨前和雨后藓结皮的呼吸速率,对比分析降雨量对藓结皮呼吸速率的影响;同时,在40 mm降雨后的0—24 h连续测定藓结皮的呼吸速率变化,分析藓结皮呼吸速率随雨后历时的变化规律。结果显示,7种降雨量后两种土壤上藓结皮的呼吸速率均显著升高,黄土上藓结皮呼吸速度的增幅为2.89—6.38倍,风沙土上藓结皮呼吸速率的增幅为0.73—4.38倍。0—6 mm降雨中,两种土壤上藓结皮的呼吸速率均随降雨量增加而迅速升高,二者成显著线性正相关关系;6—40 mm降雨中,黄土上藓结皮的呼吸速率随降雨量增加而缓慢升高,但风沙土上藓结皮的呼吸速率随降雨量增加而快速降低。两种土壤上藓结皮的呼吸速率随雨后历时表现出相似的变化规律,即雨后迅速升高、之后逐渐降低,并在24 h左右回归到雨前水平;但黄土上藓结皮的呼吸速率在雨后即刻达到峰值,而风沙土上藓结皮的呼吸速率在雨后30 min左右方达到峰值。黄土上藓结皮的呼吸速率一致高于风沙土上的藓结皮,前者在不同降雨量和雨后历时中平均比后者高150.0%和59.6%。此外,藓结皮呼吸速率与表层土壤含水量存有显著相关关系,在含水量较低(小于约4%)时二者显著正相关,在含水量较高(大于约4%)时二者对于黄土上藓结皮为正相关、对于风沙土上藓结皮为负相关。研究表明,黄土高原藓结皮土壤呼吸对降雨响应快速而直接,但其响应规律对于黄土和风沙土上的藓结皮是不同的,总体而言黄土上藓结皮对降雨的响应更为持久有效。     

Delayed ultraviolet light-induced cessation of respiration by inadequate aeration of Escherichia coli.

Inadequately aerated Escherichia coli B/r cultures did not shut their respiration off 60 min after ultraviolet light (52 M/m2 at 254 nm) as they did when well supplied with oxygen. Since cessation of respiaration is associated with cell death, the result suggested that oxygen toxicity by superoxide radicals generated by cell metabolism might be responsible for cell death. The specific activity of superoxide dismutase, which scavenges O2- radicals, increased twofold after 90 min of adequate aeration, but the specific activity of catalase remained constant. Respiration and viability of irradiated cells were affected not at all by the presence of superoxide dismutase and only slightly by the presence of catalase. Metal ions such as Mn2+ and Fe2+ inducers of superoxide dismutase, had no effect on respiration and viability. When irradiated cells were incubated under N2 for 90 min, the respiration, growth, and viability time-course responses were the same as for the cells not exposed to anareobiosis. We conclude that superoxide anions generated at the time of irradiation play no part in cessation delays the ultraviolet light-induced synthesis of proteins responsible for the irreversible cessation of respiration.     

Effect of temperature regime on diapause intensity in an adult-wintering Hymenopteran with obligate diapause

Osmia lignaria is a solitary bee that over-winters as a fully eclosed, cocooned, unfed adult. Our objective is to understand the effect of wintering temperature on diapause maintenance and termination in this species. We measure respiration rates and weight loss in individuals exposed to various wintering temperatures (0, 4, 7, 22 °C, outdoors) and durations (28, 84, 140, 196, 252 days). We use time to emerge and respiration response (respiration rate measured at 22 °C) as indicators of diapause intensity. Adults spontaneously lower their respiration rates to ∼0.1 ml/g h within 1 month after adult eclosion, indicating obligatory diapause. Non-wintered individuals maintain low respiration rates, but lose weight rapidly and die by mid-winter. In wintered adults, two phases can be distinguished. First, respiration response undergoes a rapid increase and then reaches a plateau. This phase is similar in bees wintered at 0, 4 and 7 °C. In the second phase, respiration response undergoes an exponential increase, which is more pronounced at the warmer temperatures. Composite exponential functions provide a good fit to the observed respiration patterns. Adults whose respiration response has reached 0.45 ml/g h emerge promptly when exposed to 20 °C, indicating diapause completion. Individuals wintered for short periods do not reach such respiration levels. When exposed to 20 °C these individuals lower their metabolic rate, and their emergence time is extended. The relationship between respiration rates and emergence time follows a negative exponential function. We propose two alternative models of diapause termination to interpret these results.     

Effects of 60-Hz electric fields on avoidance behavior and activity of rats

In repeated short-term tests (four sessions, each of 45-minute duration), and one longer test (a 23.5-hour session), behavior of rats was evaluated in a long, narrow shuttlebox. One side of the box was exposed to an electric field at various strengths, while a visually identical opposite side was shielded from exposure. In the short-term tests, rats generally remained shielded from electric fields of 90 kV/m and greater during the first session, and maintained this response in subsequent sessions. In the longer test, this same preference response was demonstrated at field strengths of 75 kV/m and greater; however, at 25 and 50 kV/m, rats exhibited a statistically significant preference for the exposed region of the shuttlebox, but only during the light portion of a 12-hour light: 12-hour dark cycle. Exposed animals made more traverses than sham-exposed controls between the two ends of the shuttlebox during the first hour of the test. The experimental data support the hypothesis that the observed behavioral effects are the result of direct interaction of the electric field with the animal, and not the result of secondary factors such as electric shock, corona discharge, audible noise, ozone, or vibration of the experimental apparatus.     

Influence of naloxone and yohimbine administration on pulsatile LH secretion in luteal phase beef cows

This study examined the effects of two specific neurotransmitter receptor antagonists, naloxone (NAL; mu-opioid) and yohimbine (YOH; alpha(2)-adrenergic), on pulsatile luteinizing hormone (LH) release during the luteal phase (Day 10; Day 0 = estrus) of beef cows. Treatments were saline i.m. (C; n = 4); 1mg/kg NAL i.m. followed 3 h later by two 0.5 mg/kg injections spaced 2.5 h apart (N; n = 4); 0.2 mg/kg YOH i.v. (Y; n = 3); or combined N and Y regimens, with Y preceding N by 30 min (NY; n = 4). Blood samples were collected for 8 h before (Period I) and after (Period II) initiation of treatment. Respiration rates of Y cows were similar to C cows during Period II. However, respiration rates of N and NY animals increased 70% within 30 min of the first NAL injection. Acute LH release was not observed in response to either NAL or YOH. Pulsatile LH secretion was unchanged in N, Y and NY cows during Period II when compared with Period I. In contrast, basal and pulsatile LH secretion was inhibited in C cows during Period II. The inhibition of LH secretion in C animals following NAL indicate that the cows were under stress during Period II. Thus, these data suggest that the inhibition of LH release in stressed animals can be overcome by pharmacologic attenuation of inhibitory (N) or accentuation of stimulatory (Y) signals to LHRH-containing neurons.     

Delayed Neurologic Deterioration Following Anoxia: Brain Mitochondrial and Metabolic Correlates

Hyper- but not normoglycemic cats exposed to 8 min of anoxia show neurologic signs (fasciculations, myoclonic jerks, seizures) that develop after a symptom-free period. We examined brain mitochondrial function and metabolite concentrations at 0, 1, 3, and 5 h following exposure to anoxia, to correlate biochemical findings with the presence ("symptomatic") or absence ("presymptomatic") of neurologic signs. Brain mitochondria isolated postexposure only from symptomatic cats showed markedly decreased (-50%), state 3 (ADP-stimulated), and uncoupler-stimulated respiration rates with NAD- and FAD-linked substrates. Respiratory control and ADP/oxygen (ADP/O) ratios remained unchanged, indicating, respectively, that coupling and efficiency of ATP synthesis were preserved. Thus, inhibition of electron transport chain function, not phosphorylative activity, may be rate limiting for respiration. During anoxia, hyperglycemic cats showed higher brain lactate levels (26 versus 20 mumol/g), but similar ATP and phosphocreatine concentrations, compared with normoglycemic cats. After exposure, in all animals lactate and phosphocreatine were restored to control levels, whereas ATP remained at 85%. Cats that became symptomatic demonstrated four- to sixfold increases in lactate and 50% reductions in phosphocreatine. At 3 and 5 h postexposure, symptomatic animals showed significant reductions in ATP concentrations. We conclude that although initially asymptomatic, hyperglycemic cats exposed to anoxia undergo a neurologic deterioration over several hours following reoxygenation that is correlated with inhibition of mitochondrial respiration, increases in tissue lactate, and decreases in energy state.     

Effect of different daytime and night-time temperature regimes on the foliar respiration of Pinus taeda: predicting the effect of variable temperature on acclimation

The objectives of this study were to determine the acclimation of loblolly pine (Pinus taeda L.) foliar respiration to different night-time low temperatures, daytime high temperatures, and daily mean temperatures, and then to use the responses of temperature acclimation to various temperature regimes to predict acclimation under fluctuating temperatures. Experiments were conducted on two-year-old seedlings in growth chambers using different combinations of day and night-time temperatures. The first experiment exposed trees to 22/22, 29/22, 22/15, and 29/15 degrees C day/night (d/n). When measured at a common temperature (15, 22 or 29 degrees C), respiration rates were lower for trees exposed to higher treatment temperatures and acclimation was influenced by both day and night-time temperature. However, the extent of acclimation did not relate to mean temperature, i.e. respiration rates measured at a common temperature ranked as follows for seedlings exposed to different temperature regimes, 22/15>22/22>29/15 congruent with29/22 degrees C d/n. Rather, acclimation of foliar respiration was linearly related to mean daily respiration rate, where mean daily respiration rate is the average of the respiration rates measured at the day and night-time treatment temperatures. The discrepancy between mean daily respiration rate and mean daily temperature occurred because respiration increased exponentially with increasing temperature. In a second experiment, the same seedlings were exposed to 22/22, 15/15, 25.5/18.5, and 25.5/15 degrees C d/n to test the relationship between mean daily respiration rate and acclimation. As in the first experiment, acclimation was linearly related to mean daily respiration rate. The concept of effective acclimation temperature, which is the temperature at which the mean daily respiration rate occurs, was derived from these results as a means to predict the extent that foliar respiration acclimates to treatment temperature.     

Changes in chromogranin A-immunoreactive guinea-pig pulmonary neuroendocrine cells after sensitization and challenge with ovalbumin

Immunohistochemical study with antisera to chromogranin A and neuron-specific enolase, a general marker for nerves and endocrine cells, was used to quantify changes in bronchial neuroendocrine cells in guineapigs sensitized and challenged with ovalbumin. Actively sensitized animals were killed 2, 6, 24, 48, 72, and more than 144 hours after being challenged by an aerosolized solution of ovalbumin. The number of chromogranin A-immunoreactive cells was significantly greater in sensitized but unchallenged animals and in sensitized animals killed 2 and 6 h after challenge when compared to controls; it decreased significantly in animals killed more than 24 h after challenge when compared to sensitized, unchallenged animals. The number of neuron-specific-enolase-immunoreactive cells did not change. We conclude that the peptide content of bronchial neuroendocrine cells increases during sensitization and in the early phase of a hypersensitivity reaction, and that the cells release their granule contents in the late phase of such a reaction. They may therefore play a role in immunoallergic events in the lung.     

Changes in chromogranin A-immunoreactive guinea-pig pulmonary neuroendocrine cells after sensitization and challenge with ovalbumin

Immunohistochemical study with antisera to chromogranin A and neuron-specific enolase, a general marker for nerves and endocrine cells, was used to quantify changes in bronchial neuroendocrine cells in guineapigs sensitized and challenged with ovalbumin. Actively sensitized animals were killed 2, 6, 24, 48, 72, and more than 144 hours after being challenged by an aerosolized solution of ovalbumin. The number of chromogranin A-immunoreactive cells was significantly greater in sensitized but unchallenged animals and in sensitized animals killed 2 and 6 h after challenge when compared to controls; it decreased significantly in animals killed more than 24 h after challenge when compared to sensitized, unchallenged animals. The number of neuron-specific-enolase-immunoreactive cells did not change. We conclude that the peptide content of bronchial neuroendocrine cells increases during sensitization and in the early phase of a hypersensitivity reaction, and that the cells release their granule contents in the late phase of such a reaction. They may therefore play a role in immunoallergic events in the lung.     

Daytime noise and subsequent night sleep in man

The effects of daytime noise on recovery processes during subsequent undisturbed night sleep were studied in six healthy men (21-27 years), exposed to 80 dB (A) pink noise 8 h per day for 2 days. Sleep EEG, ECG, and respiration were recorded in the laboratory for five consecutive nights: two baseline nights, two nights following noise stimulation, and again one baseline night. Additionally questionnaire data were collected, reflecting a subjective impairment of the recovery function of sleep after noise exposure. EEG sleep data of the first post-noise night showed an increase in slow wave sleep with a simultaneous decrease in stage 2 sleep. During the second post-noise night these changes were less prominent. Three subjects additionally showed an instability in the sleep course coinciding with elevated heart and respiration rates. However, altogether the autonomic parameters were not clearly affected by the noise exposure. The findings support the assumption that strong daytime noise may interfere with subsequent sleep processes.     

Combined effects of vibration and noise on palmar sweating in healthy subjects

The combined effects of vibration and noise on palmar sweating were studied experimentally in healthy subjects. Ten subjects were exposed to vibration at an acceleration of 100 m.sec-2 root mean square at a frequency of 125 Hz, a noise level of 105 dB(A) at a frequency of 1000 Hz and both stimuli together. Vibration was applied to the right hand and noise to both ears from headphones. Palmar sweating was measured by the ventilated capsule method. Vibration caused a marked increase in palmar sweating of the right hand directly exposed to vibration and also of the left hand not exposed to vibration. Simultaneous vibration and noise caused a greater increase in palmar sweating than by each of the factors separately. The combined effects tended to be greater in subjects who were more susceptible to vibration or noise.     

光照下菜豆叶片抗氰呼吸与光合作用关系的分析北大核心CSCD

为了进一步了解光照下植物呼吸作用的内在机理以及呼吸作用和光合作用的关系,该文研究了在光照下菜豆(Phaseolus vulgaris)叶片抗氰呼吸与光合作用的关系。研究发现,将黑暗下生长的菜豆幼苗叶片转到光照下10 h,总呼吸、抗氰呼吸以及抗氰呼吸在总呼吸中的比例均逐步上升;光照也导致了叶片叶绿体光合放氧和CO2固定的出现及其速率的增加,但光合放氧和CO2固定速率的增加均滞后于抗氰呼吸的增加。将黑暗下生长的叶片转到光照下之前用抗氰呼吸的抑制剂水杨基氧肟酸(SHAM)处理叶片,发现用SHAM处理并没有导致叶片在光照下光合放氧和CO2固定速率的明显变化,这也提示了黑暗下生长的叶片转至光照的过程中,抗氰呼吸和光合作用没有产生偶联。进一步研究发现,在黑暗中对叶片施加短时间的光照能够增加抗氰呼吸在总呼吸中的比例,但短时间的光照对叶片光合CO2固定速率没有影响。这些结果表明了光照对抗氰呼吸的诱导可以不依赖于光合作用,光照可能是作为一种直接的信号去诱导抗氰呼吸。     

The respiration of young coho Oncorhynchus kisutch at gradually declining oxygen levels and during recovery from oxygen deprivation

The respiration of coho salmon, Oncorhynchus kisutch , weighing between 15 and 50 g was measured at gradually declining oxygen levels and at temperatures ranging between 14 and 17°C. The maximum and minimum oxygen concentrations tested were 250 and 40 μmol L⁻¹, respectively. Respiration rates were measured for 1 h periods before oxygen concentration was lowered by 12.5 or 25.0 μmol oxygen L⁻¹. At the end of these endurance tests the oxygen level was returned to normoxic conditions and respiration rates were determined for the recovery period. Under normoxic conditions (> 200 μmol L⁻¹) the respiration of coho levelled around 5.1 μmol g⁻¹ wet weight h⁻¹. At intermediate levels between 150 and 200 μmol oxygen L⁻¹, the average rate increased to 5.8 μmol g⁻¹ h⁻¹, which could be attributed to higher spontaneous activity of the test animals. At low oxygen levels (< 150 μmol⁻¹) average respiration rates dropped to values between 5.5 and 5.7 μmol g⁻¹ h⁻¹, reaching a minimum of 3.8 μmol g⁻¹ h⁻¹ at oxygen levels below 50 μmol L^μ. First mortality was observed in this range. After exposure to reduced oxygen levels the fish maintained a higher respiration rate when again exposed to normoxic oxygen levels above 200 μmol L⁻¹. Increased respiration rates were observed for a recovery period of 6 h.     

西伯利亚蝗气门结构及呼吸代谢对高温胁迫的响应

【目的】掌握西伯利亚蝗Gomphocerus sibiricus的气门结构和呼吸代谢应对高温胁迫的响应策略。【方法】运用扫描电镜观察西伯利亚蝗气门超显微结构,多通道昆虫呼吸仪测定18~42℃处理下西伯利亚蝗的O_2吸收率、CO_2释放率、代谢率和呼吸商。【结果】西伯利亚蝗共有10对气门,胸部2对,腹部8对,呈圆形或椭圆形,内侧着生有筛板,呈刺凸状,分布密集。18~42℃范围内,随温度升高,西伯利亚蝗呼吸代谢呈先上升后下降的趋势。18℃时西伯利亚蝗雌雄成虫的O_2吸收率、CO_2释放率和代谢率值显著小于其他温度下的相应值(P<0.05),雌虫分别为0.0022 m L/min、0.0019 m L/min和0.0210 m L/(g·min),雄虫分别为0.0016 m L/min、0.0016 m L/min和0.0236 m L/(g·min);21~27℃范围内,西伯利亚蝗雌雄成虫的呼吸代谢变化平稳,超过30℃呼吸代谢各指标值迅速上升,至36℃时雌雄成虫的O_2吸收率和代谢率值均显著大于其他温度下的相应值(P<0.05);雌虫分别为0.0071 m L/min和0.0592 m L/(g·min),雄虫分别为0.0089 m L/min和0.1108 m L/(g·min),39℃时CO_2释放率显著大于其他温度下的相应值(P<0.05),雌雄成虫分别为0.0074 m L/min和0.0067 m L/min。【结论】依据西伯利亚蝗呼吸代谢随温度变化特征可以判断,随气候持续变暖,西伯利亚蝗仍将是新疆高山、亚高山草原的重要致灾类群。     

Respiration and viability of thermally injured Saccharomyces cerevisiae.

Resting cells of Saccharomyces cerevisiae Y25 were heated at 56 degrees C for 0 to 2 min. Respiratory activity of the cells reflected the severity of the heat stress. The endogenous respiration was approximately 50 microliter of O2/mg per h for cells heated for 2 min at 56 degrees C as compared with 2 microliter of O2/mg per h for nonheated cells. There was a distinct decrease in respiration after 1 to 3 h, and after 20 h the respiration rate of heated cells was less than that of nonheated cells. Along with increased rates of endogenous respiration, respiratory quotients of cells were altered after heat stress. Addition of 2,4-dinitrophenol stimulated O2 (uptake) in nonheated cells but decreased O2 (uptake) of heated cells. Due to the high rate of endogenous respiration, addition of glucose resulted in no substantial change in the rate of respiration of heated cells. However, addition of glucose prolonged the presence of the high rates of respiration observed in heated cells.     

Respiration and viability of thermally injured Saccharomyces cerevisiae.

Resting cells of Saccharomyces cerevisiae Y25 were heated at 56 degrees C for 0 to 2 min. Respiratory activity of the cells reflected the severity of the heat stress. The endogenous respiration was approximately 50 microliter of O2/mg per h for cells heated for 2 min at 56 degrees C as compared with 2 microliter of O2/mg per h for nonheated cells. There was a distinct decrease in respiration after 1 to 3 h, and after 20 h the respiration rate of heated cells was less than that of nonheated cells. Along with increased rates of endogenous respiration, respiratory quotients of cells were altered after heat stress. Addition of 2,4-dinitrophenol stimulated O2 (uptake) in nonheated cells but decreased O2 (uptake) of heated cells. Due to the high rate of endogenous respiration, addition of glucose resulted in no substantial change in the rate of respiration of heated cells. However, addition of glucose prolonged the presence of the high rates of respiration observed in heated cells.     

The respiratory performance and survival of the bivalve Macoma balthica (L.) at the southern limit of its distribution area: a translocation experiment

The hypothesis was tested that animals near their extreme Southern limits, due to high temperatures, have a high respiration rate, whereby they reach an extreme low weight-index and ultimately disappear. At estuarine stations the respiration rate of Macoma balthica (L.) (Baltic clam) did not show interseasonal changes, indicating seasonal acclimation, but within the season the respiration increased with increasing temperature, indicating the absence of short-term acclimation. In clams translocated from the Netherlands towards the Bidasoa estuary, 200 km South of their Southern distribution limit, their respiration rate was higher and weight-index lower than in specimens living in Dutch estuaries. Irrespective of an effect of the temperature, clams exposed in experiments to water from Bidasoa showed a higher respiration than clams exposed to water from the other stations. Moreover, at non-estuarine stations with a low food content, the clams showed reversed acclimation, i.e., the respiration rates in winter were much lower than summer rates, most probably a strategy to conserve energy by means of a depressed metabolism. A weight index of 5 mg DW/cm(3) and glycogen content of 2% DW are suggested as the minimal values below which the metabolic energy balance of Baltic clams becomes more negative and the clam population disappears. It was concluded that factors other than temperature influenced the respiration and weight-index of clams, and hence their presence or absence, e.g., food concentration, innate seasonal cycles, and possible pollutants in the water.